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PURPOSE National Cancer Institute–Molecular Analysis for Therapy Choice is a multicohort trial that assigns patients with advanced cancers to targeted therapies on the basis of central tumor genomic testing. Arm B evaluated afatinib, an ErbB family tyrosine kinase inhibitor, in patients with ERBB2-activating mutations. METHODS Eligible patients had selected ERBB2 single-nucleotide variants or insertions/deletions detected by the National Cancer Institute–Molecular Analysis for Therapy Choice next-generation sequencing assay. Patients had performance status ≤ 1, left ventricular ejection fraction > 50%, grade ≤ 1 diarrhea, and no prior human epidermal growth factor receptor 2 (HER2) therapy. Patients received afatinib 40 mg once daily in 28-day cycles. The primary end point was objective response rate (ORR). Secondary end points were 6-month progression-free survival, overall survival, toxicity, and molecular correlates. RESULTS A total of 59 patients were assigned and 40 were enrolled. The median age was 62 years, 78% were female, 68% had performance status = 1, and 58% had received > 3 prior therapies. The confirmed ORR was 2.7% (n = 1 of 37; 90% CI, 0.14 to 12.2), and 6-month progression-free survival was 12.0% (90% CI, 5.6 to 25.8). A confirmed partial response occurred in a patient with adenocarcinoma of extra-mammary Paget disease of skin who progressed after cycle 6. Two unconfirmed partial responses were observed (low-grade serous gynecological tract and estrogen receptor–positive/HER2-negative immunohistochemistry breast ductal carcinoma). Of 12 patients with breast cancer, 1 additional patient with lobular carcinoma (estrogen receptor–positive/HER2 fluorescent in situ hybridization) had a 51% reduction in target lesions but progressed because of a new lesion at cycle 6. The most common (> 20%) treatment-related adverse events were diarrhea (68%), mucositis (43%), fatigue (40%), acneiform rash (30%), dehydration (27%), vomiting (27%), nausea (27%), anemia (27%), and anorexia (22%). Four patients (11%) discontinued because of adverse events. CONCLUSION Although afatinib did not meet the prespecified threshold for antitumor activity in this heavily pretreated cohort, the response in a rare tumor type is notable. The safety profile of afatinib was consistent with prior studies.

ALPHABET is a randomized phase III trial assessing alpelisib + trastuzumab with or without fulvestrant in previously treated HER2-positive PIK3CA-mutated advanced breast cancer. Patients will be included in two cohorts according to hormone receptor (HR) status. In the experimental arms, patients in the HR-negative cohort will receive trastuzumab + alpelisib, and patients in the HR-positive cohort will receive the same treatment plus fulvestrant. Patients in the control arms will receive trastuzumab + physician’s choice chemotherapy (eribuline, capecitabine or vinorelbine). Key eligibility criteria include 1–4 previous lines of anti-HER2 therapy and prior trastuzumab emtansine. The primary end point is investigator-assessed progression-free survival. The study aims to recruit a total of 300 patients.

Purpose: We describe the clinical and genomic landscape of the non-small cell lung cancer (NSCLC) cohort of the AACR Project GENIE Biopharma Collaborative (BPC). Experimental Design: 1,846 patients with NSCLC whose tumors were sequenced from 2014 to 2018 at four institutions participating in AACR GENIE were randomly chosen for curation using the PRISSMMÔ data model. Progression-free survival (PFS) and overall survival (OS) were estimated for patients treated with standard therapies. Results: In this cohort, 44% of tumors harbored a targetable oncogenic alteration, with EGFR (20%), KRAS G12C (13%) and oncogenic fusions (ALK, RET and ROS1; 5%) as the most frequent. Median OS (mOS) on first-line platinum-based therapy without immunotherapy was 17.4 mo (95% confidence interval (CI) 14.9,19.5 mo). For second-line therapies, mOS was 9.2 mo (95% CI 7.5,11.3 mo) for immune checkpoint inhibitors (ICI) and 6.4 mo (95% CI 5.1,8.1 mo) for docetaxel +/- ramucirumab. In a subset of patients treated with ICI in the second-line or later setting, median RECIST PFS (2.5 mo; 95% CI 2.2, 2.8) and median real-world PFS based on imaging reports (2.2 mo; 95% CI 1.7,2.6) were similar. In exploratory analysis of the impact of tumor mutational burden (TMB) on survival on ICI treatment in the second-line or higher setting, TMB z-score harmonized across gene panels was associated with improved OS (univariable HR 0.85, p=0.03, n=247 patients). Conclusions: The GENIE BPC cohort provides comprehensive clinico-genomic data for patients with NSCLC, which can improve understanding of real-world patient outcomes.

PURPOSE To evaluate early circulating tumor DNA (ctDNA) kinetics using a tumor-naïve assay and correlate it with clinical outcomes in early phase immunotherapy (IO) trials. METHODS Plasma samples were analyzed using a 425-gene next-generation sequencing panel at baseline and before cycle 2 (3-4 weeks) in patients with advanced solid tumors treated with investigational IO agents. Variant allele frequency (VAF) for mutations in each gene, mean VAF (mVAF) from all mutations, and change in mVAF between both time points were calculated. Hyperprogression (HyperPD) was measured using Matos and Caramella criteria. RESULTS A total of 162 plasma samples were collected from 81 patients with 27 different tumor types. Patients were treated in 37 different IO phase I/II trials, 72% of which involved a PD-1/PD-L1 inhibitor. ctDNA was detected in 122 plasma samples (75.3%). A decrease in mVAF from baseline to precycle 2 was observed in 24 patients (37.5%) and was associated with longer progression-free survival (hazard ratio [HR], 0.43; 95% CI, 0.24 to 0.77; P < .01) and overall survival (HR, 0.54; 95% CI, 0.3 to 0.96; P = .03) compared with an increase. These differences were more marked if there was a >50% decrease in mVAF for both progression-free survival (HR, 0.29; 95% CI, 0.13 to 0.62; P < .001) and overall survival (HR, 0.23; 95% CI, 0.09 to 0.6; P = .001). No differences in mVAF changes were observed between the HyperPD and progressive disease patients. CONCLUSION A decrease in ctDNA within 4 weeks of treatment was associated with treatment outcomes in patients in early phase IO trials. Tumor-naïve ctDNA assays may be useful for identifying early treatment benefits in phase I/II IO trials.

Background: Despite the availability of multiple HER2-targeted therapies, most patients (pts) with advanced HER2-positive BC experience disease progression, and an unmet medical need remains. Zanidatamab (zani) binds to HER2 across a range of expression levels and induces formation of receptor clusters, resulting in receptor internalization and downregulation that affect signal transduction. Zani potently activates antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, and complement-dependent cytotoxicity. In this ongoing phase 1 study (NCT02892123), data from BC pts treated with zani monotherapy have been previously reported. Here, we evaluated the safety and antitumor activity of zani in combination with chemo in HER2-positive BC pts. Methods: Pts with locally advanced and/or metastatic HER2-positive (immunohistochemistry [IHC] 3+ or IHC 2+/fluorescence in situ hybridization+) BC who received prior trastuzumab (tras), pertuzumab (pert), and T-DM1 were enrolled. Eligibility criteria included Eastern Cooperative Oncology Group performance status ≤1 and adequate organ function. Prior history of treated stable brain metastases was allowed. Zani (20 mg/kg Q2W or 30 mg/kg Q3W) was administered in combination with paclitaxel (pac), capecitabine (cap), or vinorelbine (vin). Zani + chemo was continued until disease progression or toxicity; if chemo was discontinued due to toxicity, zani treatment could be continued. Primary endpoints were safety and tolerability assessments; secondary efficacy endpoints included objective response rate (ORR) and disease control rate (DCR; complete response [CR] + partial response [PR] + stable disease [SD]) per RECIST v1.1, and progression-free survival (PFS). Clinical benefit rate (CBR) was defined as SD ≥24 weeks or best overall response of CR or PR. Results: As of 3 May 2021, 20 HER2-positive BC pts had enrolled (zani + pac, n=4; zani + cap, n=9; zani + vin, n=7). Ten pts were hormone receptor positive (data available for 19 pts), and 7 pts had a prior history of brain metastases. Median age was 53 years (range, 38-72), with median prior systemic therapies of 4.5 (range, 2-7) and median of 2 regimens in the metastatic setting. Pts received a median of 3 prior HER2 regimens; all pts received tras and T-DM1, 17 received pert, and 6 received tyrosine kinase inhibitors. In the 16 response evaluable (measurable disease and either post-baseline assessments or earlier death/progression) pts, confirmed ORR was 37.5% (with 1 additional response pending confirmation), CBR was 50%, and DCR was 81.3%. Median duration of response was not reached (range, 1.8+ to 16.8+ mo), with 4 of 6 confirmed responses ongoing. Among all pts (n=20), the most common (≥30% of pts) zani- and/or chemo-related adverse events (AEs) were diarrhea (65%), nausea (45%), peripheral neuropathy (35%), and fatigue (30%). One pt experienced grade 3 diarrhea leading to dose reduction of zani, and 1 pt discontinued zani due to AEs (abdominal pain and nausea, both grade ≤2). Four grade 4 AEs were observed in 4 (20%) pts: neutrophil count decreased (2 pts) and neutropenia (1 pt), all related to chemo, and hyponatremia (1 pt, not related to study treatment). Serious AEs were observed in 2 (10%) pts (pleural effusion, 1 pt; pneumonitis and upper respiratory tract infection, 1 pt), none related to zani. No grade 5 AEs were reported. Conclusions: Zani in combination with chemo is well tolerated, with encouraging and durable antitumor activity in heavily pretreated (including prior tras, pert, and T-DM1) pts with HER2-positive BC. These data support further investigation of zani as a novel therapeutic for these pts. The cap and vin cohorts continue to enroll, and additional cohorts are evaluating zani ± chemo in combination with tucatinib. Citation Format: Philippe L Bedard, Seock-Ah Im, Elena Elimova, Sun Young Rha, Rachel Goodwin, Cristiano Ferrario, Keun-Wook Lee, Diana Hanna, Funda Meric-Bernstam, Jose Mayordomo, Murali Beeram, Erika Hamilton, Jorge Chaves, Melody Cobleigh, Tony Mwatha, Joseph Woolery, Do-Youn Oh. Zanidatamab (ZW25), a HER2-targeted bispecific antibody, in combination with chemotherapy (chemo) for HER2-positive breast cancer (BC): Results from a phase 1 study [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-13-07.

PURPOSE Antibiotic exposure before immune checkpoint inhibitor (ICI) treatment can negatively affect outcomes through alteration in the gut microbiome, but large-scale evaluations are lacking. We performed a population-level retrospective cohort study to evaluate the impact of antibiotic exposure before starting ICI on overall survival (OS). PATIENT AND METHODS Patients with cancer, age 65 years or older, who initiated treatment with ICIs between June 2012 and October 2018 in Ontario, Canada, were identified using systemic therapy administration data. The cohort was deterministically linked to other health care databases to obtain covariates and antibiotic prescription claim data at both 1 year and 60 days before ICI therapy. Multivariable Cox models evaluated the association between exposure and OS. RESULTS Among the 2,737 patients with cancer who received ICIs, 59% and 19% of patients received antibiotics 1 year and 60 days before ICI therapy, respectively. Median OS was 306 days. Any antibiotic exposure within 1 year before ICI was associated with worse OS (adjusted hazard ratio [aHR], 1.12; 95% CI, 1.12 to 1.23; P = .03). In antibiotic class analysis, exposure to fluoroquinolones within 1 year (aHR, 1.26; 95% CI, 1.13 to 1.40; P < .001) or 60 days before ICI (aHR, 1.20; 95% CI, 0.99 to 1.45; P = .06) was associated with worse OS, with a dose effect seen on the basis of total weeks of exposure over 1 year (aHR, 1.07 per week; 95% CI, 1.03 to 1.11; P < .001) and 60 days (aHR, 1.12 per week; 95% CI, 1.03 to 1.23; P = .01). CONCLUSION In this population-level study, exposure to antibiotics and specifically fluoroquinolones before ICI therapy was observed to be associated with worse OS among older adults with cancer. Interventions aimed at altering the gut microbiome to boost immunogenicity may help improve outcomes for patients receiving ICIs with prior antibiotic exposure.

ImportanceIt is estimated that up to 50% of patients with ERBB2 (HER2)-positive metastatic breast cancer (MBC) will develop brain metastases (BMs), which is associated with poor prognosis. Previous reports of the HER2CLIMB trial have demonstrated that tucatinib in combination with trastuzumab and capecitabine provides survival and intracranial benefits for patients with ERBB2-positive MBC and BMs.ObjectiveTo describe overall survival (OS) and intracranial outcomes from tucatinib in combination with trastuzumab and capecitabine in patients with ERBB2-positive MBC and BMs with an additional 15.6 months of follow-up.Design, Setting, and ParticipantsHER2CLIMB is an international, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating tucatinib in combination with trastuzumab and capecitabine. The 612 patients, including those with active or stable BMs, had ERBB2-positive MBC previously treated with trastuzumab, pertuzumab, and trastuzumab emtansine. The study was conducted from February 23, 2016, to May 3, 2019. Data from February 23, 2016, to February 8, 2021, were analyzed.InterventionsPatients were randomized 2:1 to receive tucatinib (300 mg orally twice daily) or placebo (orally twice daily), both in combination with trastuzumab (6 mg/kg intravenously or subcutaneously every 3 weeks with an initial loading dose of 8 mg/kg) and capecitabine (1000 mg/m2 orally twice daily on days 1-14 of each 3-week cycle).Main Outcomes and MeasuresEvaluations in this exploratory subgroup analysis included OS and intracranial progression-free survival (CNS-PFS) in patients with BMs, confirmed intracranial objective response rate (ORR-IC) and duration of intracranial response (DOR-IC) in patients with measurable intracranial disease at baseline, and new brain lesion–free survival in all patients. Only OS was prespecified before the primary database lock.ResultsAt baseline, 291 of 612 patients (47.5%) had BMs. Median age was 52 years (range, 22-75 years), and 289 (99.3%) were women. At median follow-up of 29.6 months (range, 0.1-52.9 months), median OS was 9.1 months longer in the tucatinib-combination group (21.6 months; 95% CI, 18.1-28.5) vs the placebo-combination group (12.5 months; 95% CI, 11.2-16.9). The tucatinib-combination group showed greater clinical benefit in CNS-PFS and ORR-IC compared with the placebo-combination group. The DOR-IC was 8.6 months (95% CI, 5.5-10.3 months) in the tucatinib-combination group and 3.0 months (95% CI, 3.0-10.3 months) in the placebo-combination group. Risk of developing new brain lesions as the site of first progression or death was reduced by 45.1% in the tucatinib-combination group vs the placebo-combination group (hazard ratio, 0.55 [95% CI, 0.36-0.85]).Conclusions and RelevanceThis subgroup analysis found that tucatinib in combination with trastuzumab and capecitabine improved OS while reducing the risk of developing new brain lesions, further supporting the importance of this treatment option for patients with ERBB2-positive MBC, including those with BMs.Trial RegistrationClinicalTrials.gov Identifier: NCT02614794

BACKGROUND: Long-term response to HER2-targeted therapies is infrequent in metastatic breast cancer (MBC). We evaluated clinical characteristics of HER2-positive MBC patients with no evidence of disease (NED) vs residual disease (RES) experiencing long-term response to first-line HER2-targeted therapy. METHODS: Patients receiving first-line chemotherapy-trastuzumab (CT) or taxane-trastuzumab-pertuzumab (THP) with response duration ≥2-fold higher than in phase II/III trials (CT [18.2 months]; THP [40.4 months]) were included. Clinical characteristics and radiographic review for NED or RES was evaluated by Cox-regression (hazard ratio; HR) or Kaplan–Meier (log-rank). Characteristics associated with NED were evaluated by logistic regression (Odds; OR). RESULTS: From 01/2005-01/2016, N = 103 (4.6%) patients were identified. In multivariate analyses, NED (N = 46) showed improved progression-free (PFS) and overall survival (OS) [p

Background Testicular cancer survivors often have impaired gonadal function possibly related to chemotherapy. Platinum is a heavy metal that can be detected at low levels in serum many years after treatment, it is not known whether platinum also persists in semen and if platinum persistence in semen is associated with impaired fertility. Methods Adult cisplatin‐treated testicular cancer survivors were enrolled. High‐Performance Liquid Chromatography‐tandem mass spectrometry was used to measure semen and serum platinum levels. Semen quality and DNA Fragmentation Index (DFI) were assessed. Results From 11/2017 to 12/2019, 38 patients (median age 32 years; range: 19–52) were enrolled. Median cumulative cisplatin dose was 301 mg/m2 (range: 274–404). Platinum levels were higher in semen than in blood (p = 0.03). Semen platinum levels were not significantly associated with time from last cisplatin dosing (r = −0.34; p = 0.09) nor cumulative dose (r = −0.10, p = 0.63). Sperm concentration was correlated with time from last cisplatin dosing (r = 0.58, p

Immune-checkpoint inhibitors have profoundly changed the treatment landscape for many tumor types. Despite marked improvements in disease control for highly immunogenic cancers, the clinical impact of checkpoint inhibitors in breast cancers to date is limited. Breast cancer is a heterogeneous disease with different levels of PD-L1 expression and variable tumor microenvironment (TME) composition according to molecular subtype. With emerging evidence of the role of different factors involved in immune evasion, there are promising new immunotherapy targets that will reshape early drug development for metastatic breast cancer. This review examines the available evidence for existing and emerging immuno-oncology (IO) approaches including small molecules targeting different regulators of the cancer-immunity cycle.

Serial circulating tumor DNA (ctDNA) monitoring is emerging as a non-invasive strategy to predict and monitor immune checkpoint blockade (ICB) therapeutic efficacy across cancer types. Yet, limited data exist to show the relationship between ctDNA dynamics and tumor genome and immune microenvironment in patients receiving ICB. Here, we present an in-depth analysis of clinical, whole-exome, transcriptome, and ctDNA profiles of 73 patients with advanced solid tumors, across 30 cancer types, from a phase II basket clinical trial of pembrolizumab (NCT02644369) and report changes in genomic and immune landscapes (primary outcomes). Patients stratified by ctDNA and tumor burden dynamics correspond with survival and clinical benefit. High mutation burden, high expression of immune signatures, and mutations in BRCA2 are associated with pembrolizumab molecular sensitivity, while abundant copy-number alterations and B2M loss-of-heterozygosity corresponded with resistance. Upon treatment, induction of genes expressed by T cell, B cell, and myeloid cell populations are consistent with sensitivity and resistance. We identified the upregulated expression of PLA2G2D, an immune-regulating phospholipase, as a potential biomarker of adaptive resistance to ICB. Together, these findings provide insights into the diversity of immunogenomic mechanisms that underpin pembrolizumab outcomes., Although circulating tumour DNA (ctDNA) can predict immune checkpoint blockade (ICB) responses, its association with tumour biomarkers remains unknown. Here, the authors use ctDNA to inform exome and transcriptome profiling of >100 patients with 30 cancer types on a single clinical ICB trial and identify tumour microenvironment features associated with response.

PURPOSE Testicular cancer survivors may experience mental illness as a consequence of their cancer diagnosis and treatment. METHODS All incident cases of testicular cancer treated with orchiectomy in Ontario, Canada (2000-2010), were identified using the Ontario Cancer Registry. Cases were matched to controls in a 1:5 ratio on age and geography. Population-level databases were used to identify mental health service use episodes; outpatient use included visits to a general practitioner for a mental health concern or any visit to a psychiatrist. Negative binomial regression modeling was used to estimate the rate of mental health service use in the pretreatment (2 years prior until 1 month before orchiectomy), peritreatment (1 month before until 1 month after orchiectomy), and post-treatment periods (1 month after orchiectomy until end of follow-up). Rate ratios (RR) comparing cases with controls in the peri- and post-treatment periods were adjusted for baseline mental health service use. RESULTS Two thousand six hundred nineteen cases of testicular cancer were matched to 13,095 controls. There was no baseline difference in the rate of mental health service use. Cases were significantly more likely than controls to have an outpatient visit for a mental health concern in the peritreatment (adjusted RR [aRR], 2.45; 95% CI, 2.06 to 2.92) and post-treatment periods (aRR, 1.30; 95% CI, 1.12 to 1.52). The difference in mental health service use persisted over a median follow-up of 12 years. In the postorchiectomy period, cases with baseline mental health service use were those most likely to use mental health services (aRR, 5.64; 95% CI, 4.64 to 6.85). CONCLUSION Testicular cancer survivors use mental health services more often than healthy controls. Survivorship care plans that address the long-term mental healthcare needs of this population are needed.

Background Clinician reporting of symptomatic adverse events (AEs) in phase I trials uses the Common Terminology Criteria for Adverse Events (CTCAE). The utility of the patient-reported outcomes (PROs) version of the CTCAE (PRO-CTCAE) in this setting is unknown. This prospective, observational study compared patient- and clinician-reported symptomatic AEs in phase I patients. Methods Phase I study–eligible patients at Princess Margaret were surveyed with the PRO-CTCAE full-item library (78 symptomatic AEs) at baseline (BL), mid-cycle 1, and mid-cycle 2 (C2). Patient and trial characteristics, best response, and survival data were collected. Presence or absence of patient- (PRO-CTCAE) or clinician-reported symptomatic AEs were compared (kappa) at defined timepoints and overall (BL+ mid-cycle 1 + C2). Results Of 292 patients approached from May 2017 to January 2019, a total of 265 (90.8%) were consented, with 243 (91.7%) evaluable and 552 PRO-CTCAE surveys (completion rate = 98.7%) included in analyses. Evaluation of overall patient-reported symptomatic AEs identified 50 PRO-CTCAE and 11 CTCAE items with 10% or greater reporting frequency. Nineteen CTCAE items were reported as 1% or less despite matched PRO-CTCAE items reporting as 10% or greater. Underreported categories included sexual health, bodily emissions, and cognition. Clinician- relative to patient-reporting frequency (ratio) demonstrated 9 symptomatic AEs with a 50-fold or more lower clinician reporting rate. Overall patient–clinician agreement for individual symptomatic AEs ranged from poor (κ = 0.00-0.19) to moderate (κ = 0.40-0.59), with discordance driven by lack of clinician reporting. Dyspnea (κ = 0.54) and peripheral neuropathy (κ = 0.63) at BL and limb edema (κ = 0.55) at C2 demonstrated the highest patient–clinician agreement. Conclusions Poor to moderate patient–clinician agreement for symptomatic AEs suggests clinician underreporting in phase I trials. Analyses of severity and interference PRO categories are ongoing.

Background Mutations in p110α, encoded by PIK3CA, are present in ~40% of HR+/HER2- BCs. GDC-0077, a PI3Kα-selective inhibitor and mutant PI3Kα degrader, elicits antitumor activity in PIK3CAmut preclinical models as a single agent and when combined with endocrine therapy (ET). New evidence suggests BCs harboring multiple PIK3CAmut exhibit increased signaling through the PI3K/AKT pathway and are more sensitive to PI3Kα inhibitors compared with BCs with a single PIK3CAmut. We report a preliminary analysis of PIK3CAmut status with clinical outcomes from an ongoing study of GDC-0077 alone or with ET (letrozole/fulvestrant) ± palbociclib (palbo) in pts with PIK3CAmut HR+/HER2- mBC (NCT03006172). Methods Detectable PIK3CAmut from local tumor tissue/blood-based assay or tumor tissue by cobas PIK3CA assay were required to enroll. Plasma-derived circulating tumor (ct) DNA was collected at baseline (BL), cycle 1 day 15 (C1D15), and C2D1 (in the cohort where GDC-0077 starts at C1D15) to detect PIK3CAmut. Paired tumor samples were analyzed for Ki67 and pAKT/pS6 expression by immunohistochemistry. Single vs multiple PIK3CAmut was correlated with the percentage of pharmacodynamic (PD) inhibition of Ki67/pAKT/pS6 expression; with the PIK3CAmut allele frequency ratio between BL and C1D15 or C2D1 (MAFr15); with best overall response (BOR, RECIST v1.1); and with time on treatment (TOT) in days. Statistical analyses: Kruskal-Wallis and Mann-Whitney-Wilcoxon for group and pairwise comparisons, respectively, and two-sample proportion testing for categorical comparisons. Results Data cutoff was 03/20/2020. PIK3CAmut were detected in 87/103 (84.5%) pts with BL ctDNA available for sequencing. Multiple PIK3CAmut were detected in 21/87 (24.1%) BL ctDNA samples: 9 from pts treated with single-agent GDC-0077; 8 from pts treated with GDC-0077 + letrozole/fulvestrant; and 4 from pts treated with GDC-0077 + letrozole/fulvestrant + palbo. The median number of lines of prior therapy for metastatic disease was not different between pts with multiple (3.0 lines) vs single (2.5 lines) PIK3CAmut detected at BL (p = 0.205). Median percentage inhibition of Ki67/pAKT/pS6 expression was greater in pts with multiple (-65.8, -70.3, -66.8%, respectively) vs single (-42.1, -34.1, -29.5%) PIK3CAmut detected at BL (p = 0.095, 0.002, 0.056). Median MAFr15 was lower in pts with multiple (MAFr15 0.01) vs single PIK3CAmut (MAFr15 0.15) detected at BL (p = 0.004). Of 73 pts with both BL ctDNA-detected PIK3CAmut and BOR data, 16/16 (100%) with multiple PIK3CAmut experienced BOR of partial response (PR) or stable disease (SD) while 42/57 (73.7%) with single PIK3CAmut experienced BOR of PR or SD (p = 0.051). No pts with multiple PIK3CAmut detected experienced a BOR of progressive disease. Median TOT was greater in pts with multiple PIK3CAmut (196 days) vs single PIK3CAmut (140.5 days) detected at BL, but this was not significant (p = 0.1804). Conclusions The fraction of pts in which multiple PIK3CAmut were identified from BL ctDNA in this HR+/HER2- mBC dataset (24.1%) was slightly higher than reported elsewhere. This may be due to the method of detection (blood vs tissue) and/or the definition of multiple PIK3CAmut used. Pts in which multiple PIK3CAmut were detected by ctDNA exhibited greater depth of PD biomarker inhibition in tumors and experienced PR/SD more often compared with pts in which only one PIK3CAmut was detected. However, no significant associations were observed with the number of prior lines of therapy for metastatic disease or TOT. The dataset is currently too small to assess the impact of different treatment regimens in this study but will be re-evaluated as the data mature. Citation Format: Komal Jhaveri, Dejan Juric, Andrea Varga, Nicolas Turner, Peter Schmid, Cristina Saura, Mafalda Oliveira, Ian E Krop, Kevin Kalinsky, Antoine Italiano, Erika Hamilton, Valentina Gambardella, Andrés Cervantes, Philippe L Bedard, Bonnie P Liu, Jessica W Chen, Junko Aimi, Stephanie Royer-Joo, Jennifer L Schutzman, Katherine E Hutchinson. Preliminary correlative analysis of clinical outcomes with PIK3CA mutation (mut) status from a phase I/Ib study of GDC-0077 in patients (pts) with hormone receptor-positive/HER2-negative metastatic breast cancer (HR+/HER2- mBC) [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS5-12.

Purpose: To evaluate patient-reported outcomes of adolescents and young adults (AYAs) with breast cancer treated with curative intent. Methods: AYA breast cancer patients (defined as diagnosed between 18 to 39 years of age) treated at a large tertiary cancer centre between January 2014 and December 2016 were identified. Patients routinely complete the validated symptom screening tool, the Edmonton Symptom Assessment System-revised (ESAS-r) prior to their clinical encounter. Scores from diagnosis up to 24 months post-diagnosis were obtained from our internal database, with elevated scores defined as > 4 for each individual symptom (rated 0-10). Patient, clinical and treatment characteristics were extracted from medical records. Descriptive statistics were used to describe patient, clinical and treatment characteristics, and ESAS-r scores. Time to recurrence was calculated from diagnosis to local or regional recurrence, distant metastasis or death (whichever occurred first). Kaplan-Meier survival analysis and log-rank tests were used to compare time to recurrence between women with vs. without elevated symptom scores. Chi-squared test was used to test the change in number of patients with elevated symptom scores over time. Univariable and multivariable logistic regression models were carried out to assess association between various factors and ESAS-r symptoms of depression, anxiety and well-being within 24 months of diagnosis. Results: Among 258 patients identified, 211 (82%) had accompanying ESAS-r and were eligible for analysis. Median follow-up was 3.9 years. Median age at diagnosis was 35 (20-39), most were clinical stage 2/3 at diagnosis (63%), 20% had triple negative disease, 76% received chemotherapy and 81% received radiotherapy. Overall, symptom burden was the highest (scores > 4) for decreased well-being (52%), tiredness (48%) and anxiety (44%). Although symptom burden significantly improved over time, 43%, 38% and 33% of patients, respectively, reported elevated symptoms 24 months post-diagnosis. Multivariable analysis found that elevated anxiety was significantly associated with younger age at diagnosis (p=0.036), receipt of chemotherapy (p=0.01) and presence of long-term toxicity (p=0.0032). Elevated depression, anxiety and well-being were significantly associated with referral to Psychosocial Oncology (p=0.024, p=0.036 and p=0.019, respectively), whereas well-being was also associated with referral to Survivorship Clinic (p=0.043). However, overall rates of referral (24-36%) were much lower than symptom prevalence. There was no association between elevated symptoms and time to recurrence. Conclusion: AYAs diagnosed with breast cancer report high symptom burden that continues to persist up to 24-months post-diagnosis. Patients with elevated psychosocial distress are more likely to be referred to Psychosocial Oncology and Survivorship clinics, indicating that the ESAS-r is a useful screening tool in a real-world setting. However, a gap between symptom burden and intervention exists, providing opportunities for future research. Citation Format: Revathy Krishnamurthy, Tulin Cil, Philippe Bedard, Robin Forbes, Madeline Li, Zhihui (Amy) Liu, Jennifer Croke. Patient-reported outcomes of adolescents and young adults with breast cancer treated with curative intent [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD12-09.

Purpose:Somatic mutations in phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), which encodes the p110α catalytic subunit of PI3K, are found in multiple human cancers. While recurrent mutations in PIK3CA helical, regulatory, and kinase domains lead to constitutive PI3K pathway activation, other mutations remain uncharacterized. To further evaluate their clinical actionability, we designed a basket study for patients with PIK3CA-mutant cancers with the isoform-specific PI3K inhibitor taselisib.Patients and Methods:Patients were enrolled on the basis of local PIK3CA mutation testing into one of 11 histology-specific cohorts and treated with taselisib at 6 or 4 mg daily until progression. Tumor DNA from baseline and progression (when available) was sequenced using a next-generation sequencing panel. Exploratory analyses correlating genomic alterations with treatment outcomes were performed.Results:A total of 166 patients with PIK3CA-mutant cancers were enrolled. The confirmed response rate was 9%. Activity varied by tumor type and mutant allele, with confirmed responses observed in head and neck squamous (15.4%), cervical (10%), and other cancers, plus in tumors containing helical domain mutations. Genomic analyses identified mutations potentially associated with resistance to PI3K inhibition upfront (TP53 and PTEN) and postprogression through reactivation of the PI3K pathway (PTEN, STK11, and PIK3R1). Higher rates of dose modification occurred at higher doses of taselisib, indicating a narrow therapeutic index.Conclusions:Taselisib had limited activity in the tumor types tested and is no longer in development. This genome-driven study improves understanding of the activity, limitations, and resistance mechanisms of using PI3K inhibitors as monotherapy to target PIK3CA-mutant tumors.

The purpose of this study is to describe the long-term toxicities of intracranial germ cell tumor (IGCT) in the adolescent and young adult (AYA) population. We report late toxicities of a multi-center cohort of AYA patients treated for IGCT between 1975 and 2015. Charts were retrospectively reviewed for hormone deficiency, ototoxicity, seizure disorder, visual deterioration, cerebrovascular events, second neoplasm, psychiatric illness, and neurocognitive impairment. Statistical analysis was performed for late toxicities to evaluate the influence of select factors. Our patient cohort included 112 patients with IGCTs; 84% of patients had a germinoma as opposed to a non-germinomatous germ cell tumor (NGGCT), median age at radiotherapy (RT) was 19 years, and median follow-up was 8.3 years. Of the 94 patients with germinoma, 32 (34%) received both chemotherapy and RT as part of their upfront treatment, while 62 (66%) received RT alone. All 18 patients with NGGCT received chemotherapy and RT. The most common late toxicity following IGCT treatments was physician-reported neurocognitive impairment, with a 10-year cumulative incidence (CI) of 38.5%. Ten-year CI of treatment-induced ototoxicity was 39.2% for patients who received cisplatin, compared to 3.6% for those who received carboplatin but no cisplatin (p

Immune checkpoint blockade (ICB) provides clinical benefit to a subset of patients with cancer. However, existing biomarkers do not reliably predict treatment response across diverse cancer types. Limited data exist to show how serial circulating tumor DNA (ctDNA) testing may perform as a predictive biomarker in patients receiving ICB. We conducted a prospective phase II clinical trial to assess ctDNA in five distinct cohorts of patients with advanced solid tumors treated with pembrolizumab (NCT02644369). We applied bespoke ctDNA assays to 316 serial plasma samples obtained at baseline and every three cycles from 94 patients. Baseline ctDNA concentration correlated with progression-free survival, overall survival, clinical response and clinical benefit. This association became stronger when considering ctDNA kinetics during treatment. All 12 patients with ctDNA clearance during treatment were alive with median 25 months follow up. This study demonstrates the potential for broad clinical utility of ctDNA-based surveillance in patients treated with ICB. Siu and colleagues use a bespoke ctDNA assay and show predictive utility of longitudinal ctDNA analysis in a phase II clinical trial of patients receiving pembrolizumab that included multiple solid tumor types.

PURPOSE In the HER2CLIMB study, patients with human epidermal growth factor receptor 2 (HER2)–positive breast cancer with brain metastases (BMs) showed statistically significant improvement in progression-free survival (PFS) with tucatinib. We describe exploratory analyses of intracranial efficacy and survival in participants with BMs. PATIENTS AND METHODS Patients were randomly assigned 2:1 to tucatinib or placebo, in combination with trastuzumab and capecitabine. All patients underwent baseline brain magnetic resonance imaging; those with BMs were classified as active or stable. Efficacy analyses were performed by applying RECIST 1.1 criteria to CNS target lesions by investigator assessment. CNS-PFS (intracranial progression or death) and overall survival (OS) were evaluated in all patients with BMs. Confirmed intracranial objective response rate (ORR-IC) was evaluated in patients with measurable intracranial disease. RESULTS There were 291 patients with BMs: 198 (48%) in the tucatinib arm and 93 (46%) in the control arm. The risk of intracranial progression or death was reduced by 68% in the tucatinib arm (hazard ratio [HR], 0.32; 95% CI, 0.22 to 0.48; P < .0001). Median CNS-PFS was 9.9 months in the tucatinib arm versus 4.2 months in the control arm. Risk of death was reduced by 42% in the tucatinib arm (OS HR, 0.58; 95% CI, 0.40 to 0.85; P = .005). Median OS was 18.1 versus 12.0 months. ORR-IC was higher in the tucatinib arm (47.3%; 95% CI, 33.7% to 61.2%) versus the control arm (20.0%; 95% CI, 5.7% to 43.7%; P = .03). CONCLUSION In patients with HER2-positive breast cancer with BMs, the addition of tucatinib to trastuzumab and capecitabine doubled ORR-IC, reduced risk of intracranial progression or death by two thirds, and reduced risk of death by nearly half. To our knowledge, this is the first regimen to demonstrate improved antitumor activity against BMs in patients with HER2-positive breast cancer in a randomized, controlled trial.

BackgroundRecent studies have demonstrated that T cells can induce vasodilation in a choline-acetyltransferase dependent manner, leading to an increase in T cell migration to infected tissues in response to viral infection, but its role in cancer is unclear. Choline acetyltransferase catalyzes the production of acetylcholine from choline and acetyl-CoA, however, acetylcholine is challenging to quantify due to its extremely short half-life while choline is stable. This study aims to correlate serum choline levels in patients with advanced solid tumors receiving pembrolizumab with treatment outcomes.MethodsBlood samples were collected at baseline and at week 7 (pre-cycle 3) in patients treated with pembrolizumab in the INvestigator-initiated Phase 2 Study of Pembrolizumab Immunological Response Evaluation phase II trial (NCT02644369). Samples were analyzed for choline and circulating tumor DNA (ctDNA). Multivariable Cox models were used to assess the association between choline and overall survival (OS) and progression-free survival (PFS) when including ΔctDNAC3 (the change in ctDNA from baseline to cycle 3), cohort, PD-L1 expression and tumor mutation burden (TMB). An independent validation cohort from the LIBERATE study (NCT03702309) included patients on early phase trials treated with a PD-1 inhibitor.ResultsA total of 106 pts were included in the analysis. With a median follow-up of 12.6 months, median PFS and OS were 1.9 and 13.7 months, respectively. An increase in serum choline level at week 7 compared with baseline (ΔcholineC3) in 81 pts was significantly associated with a better PFS (aHR 0.48, 95% CI 0.28 to 0.83, p=0.009), and a trend toward a better OS (aHR 0.64, 95% CI 0.37 to 1.12, p=0.119). A combination of ΔctDNAC3 and ΔcholineC3 was prognostic for both OS and PFS. Multivariable analyses show ΔcholineC3 was a prognostic factor for PFS independent of ΔctDNAC3, cohort, PD-L1 and TMB. In the independent validation cohort (n=51), an increase in serum choline at cycle 2 was associated with a trend to improved PFS.ConclusionsThis is the first exploratory report of serum choline levels in pan-cancer patients receiving pembrolizumab. The association between improved PFS and ΔcholineC3 suggests a possible role for the cholinergic system in the regulation of antitumor immunity. Further pre-clinical and clinical studies are required to validate this finding.Trial registration numberNCT03702309.

Epidermal growth factor receptor (EGFR)- and human epidermal growth factor receptor (HER)2-targeted therapies are approved for the treatment of breast, gastric/gastrointestinal junction (GEJ), and non-small cell lung cancer (NSCLC) with specific molecular aberrations affecting HER family members. Over 10 % of other cancers harbor genomic aberrations affecting HER family members, but their role remains undefined.The MOBILITY3 trial evaluated the antitumor activity of afatinib, an oral pan-HER tyrosine kinase inhibitor (TKI) in HER-aberrant tumors outside of the licensed indications.In this single-center basket trial, patients with advanced solid tumors that harbor mutations and/or amplifications of any of the HER family members (EGFR, ERBB2, ERBB3, ERBB4) were enrolled. The EGFR-mutated NSCLC and HER2-positive breast cancers were excluded. Participants were treated with oral afatinib 40 mg daily until disease progression or unacceptable toxicity. Objective response rate (ORR) and progression-free survival (PFS) were primary and secondary endpoints, respectively.The study enrolled 12 patients with 6 tumor types (NSCLC, sarcoma, salivary gland, gastric/GEJ, breast and pancreatic cancer). Objective response rate was 8 % (95 % CI 0.2-38%) and median PFS was 11.4 weeks (95% CI 4.6-33.3 weeks). All 3 patients with salivary gland cancers and 1 patient with ERBB2-mutant NSCLC had clinical benefit (stable disease or partial response lasting 24 weeks). Due to slow accrual and a lower-than-expected response rate, trial recruitment was terminated before the target of 30 patients were enrolled.In the MOBILITY3 study (NCT02506517), afatinib demonstrated modest activity in tumors that possess EGFR and ERBB2 aberrations. Clinical benefit seen in all 3 salivary gland cancers supports the growing evidence for the utility of HER-targeted therapies in the treatment of this specific tumor type.

Adverse event (AE) reporting in early-phase clinical trials is essential in determining the tolerability of experimental anticancer therapies. The patient-reported outcome version of the CTCAE (PRO-CTCAE) evaluates AE components such as severity and interference in daily life. The aim of this study was to correlate the grade of clinician-reported AEs with patients' reported experience of these toxicities using PRO-CTCAE.Patients with advanced solid tumours enrolled on Phase I clinical trials were surveyed using the PRO-CTCAE. Symptomatic AEs were recorded by physicians using the CTCAE. A logistic regression model was used to assess associations between CTCAE grade and PRO responses.Of 219 evaluable patients, 81 experienced a high-grade (3/4) clinician-reported symptom, and of these, only 32 (40%) and 26 (32%) patients concordantly reported these as either severe or very severe, and interfering with daily life either 'quite a bit' or 'very much', respectively. Of the 137 patients who experienced a low-grade (1/2) clinician-reported AE as their worst symptom, 98 (72%) and 118 (86%) patients concordantly reported these as either mild-moderate severity and minimally interfering with daily life, respectively. There was a statistically significant association between clinician-reported AE grade and interference. Interference scores were also associated with dose reductions.This is the first study to explore patient-reported severity and interference from symptomatic toxicities and compare clinician grading of the same toxicities. The study provided further evidence to support the added value of the PRO-CTCAE in Phase I oncology trials, which would make AE reporting patient-centred. Further work is needed to determine how this would affect the assessment of tolerability.

BackgroundTrametinib is an oral MEK 1/2 inhibitor, with a single agent recommended phase 2 dose (RP2D) of 2 mg daily (QD). This study was designed to evaluate RP2D, maximum tolerated dose (MTD), and pharmacokinetic (PK) profile of trametinib in patients with advanced solid tumors who had various degrees of hepatic dysfunction (HD).MethodsAdvanced cancer patients were stratified into 4 HD groups based on Organ Dysfunction Working Group hepatic function stratification criteria: normal (Norm), mild (Mild), moderate (Mod), severe (Sev). Dose escalation was based on “3 + 3” design within each HD group. PK samples were collected at cycle 1 days 15-16.ResultsForty-six patients were enrolled with 44 evaluable for safety [Norm=17, Mild=7, Mod (1.5 mg)=4, Mod (2 mg)=5, Sev (1 mg)=9, Sev (1.5 mg)=2] and 22 for PK analysis. Treatment related adverse events were consistent with prior trametinib studies. No treatment related deaths occurred. Dose limiting toxicities (DLTs) were evaluable in 15 patients (Mild=6, Mod (1.5 mg)=3, Mod (2 mg)=2, Sev (1 mg)=3 and Sev (1.5 mg)=1). One DLT (grade 3 acneiform rash) was observed in a Sev patient (1.5 mg). Dose interruptions or reductions due to treatment related adverse events occurred in 15 patients (34%) [Norm=9, 53%; Mild=2, 29%; Mod (1.5 mg)=1, 33%; Mod (2 mg)=2, 33%; Sev (1 mg)=1, 11%; Sev (1.5 mg)=1; 50%]. There were no significant differences across HD groups for all PK parameters when trametinib was normalized to 2 mg. However, only limited PK data were available for the Mod (n = 3) and Sev (n = 3) groups compared to Norm (n = 10) and Mild (n = 6) groups. Trametinib is heavily protein bound, with no correlation between serum albumin level and unbound trametinib fraction (p = 0.26).ConclusionsRP2D for trametinib in Mild HD patients is 2 mg QD. There are insufficient number of evaluable patients due to difficulty of patient accrual to declare RP2D and MTD for Mod and Sev HD groups. DLTs were not observed in the highest dose cohorts that reached three evaluable patients – 1.5 mg QD in Mod group, and 1 mg QD in Sev group.Trial registrationThis study was registered in the ClinicalTrials.gov website (NCT 02070549) on February 25, 2014. .

Importance Real-world data sets that combine clinical and genomic data may be subject to left truncation (when potential study participants are not included because they have already passed the milestone of interest at the time of study recruitment). The lapse between diagnosis and molecular testing can present analytic challenges and threaten the validity and interpretation of survival analyses. Observations Effects of ignoring left truncation when estimating overall survival are illustrated using data from the American Association for Cancer Research (AACR) Project Genomics Evidence Neoplasia Information Exchange Biopharma Collaborative (GENIE BPC), and a straightforward risk-set adjustment approach is described. Ignoring left truncation results in overestimation of overall survival: unadjusted median survival estimates from diagnosis among patients with stage IV non-small cell lung cancer or stage IV colorectal cancer were overestimated by more than 1 year. Conclusions and relevance Clinicogenomic data are a valuable resource for evaluation of real-world cancer outcomes and should be analyzed using appropriate methods to maximize their potential. Analysts must become adept at application of appropriate statistical methods to ensure valid, meaningful, and generalizable research findings.

PURPOSE Concurrent PIK3CA mutations and fibroblast growth factor receptor (FGFR) alterations occur in multiple cancer types, including estrogen receptor–positive breast cancer, bladder cancer, and endometrial cancer. In this first-in-human combination trial, we explored safety and preliminary efficacy of combining the PI3Kα selective inhibitor alpelisib with the FGFR1-4 selective inhibitor infigratinib. PATIENTS AND METHODS Patients with PIK3CA-mutant advanced solid tumors, with or without FGFR1-3 alterations, were enrolled in the dose escalation or one of three molecular-defined dose-expansion cohorts. The primary end point was the maximum tolerated dose. Secondary end points included safety, pharmacokinetics, and response. Archival tumor samples were sequenced to explore genomic correlates of response. RESULTS In combination, both agents were escalated to full, single-agent recommended doses (alpelisib, 300 mg per day continuously; infigratinib, 125 mg per day 3 weeks on followed by 1 week off). The toxicity profile of the combination was consistent with the established safety profile of each agent, although 71% of all patients required at least one treatment interruption or dose reduction. Molecularly selected dose expansions in breast cancer and other solid tumors harboring PIK3CA mutations, alone or in combination with FGFR alterations, identified sporadic responses, predominately in tumor types and genotypes previously defined to have sensitivity to these agents. CONCLUSION The combination of alpelisib and infigratinib can be administered at full single-agent doses, although the high rate of dose interruption or reduction suggests long-term tolerability may be challenging. In exploratory signal-seeking cohorts of patients harboring dual PIK3CA and FGFR1-3 alterations, no clear evidence of synergistic activity was observed.

BackgroundThe combination of antiangiogenic agents with immune checkpoint inhibitors could potentially overcome immune suppression driven by tumor angiogenesis. We report results from a phase IB study of ziv-aflibercept plus pembrolizumab in patients with advanced solid tumors.MethodsThis is a multicenter phase IB dose-escalation study of the combination of ziv-aflibercept (at 2–4 mg/kg) plus pembrolizumab (at 2 mg/kg) administered intravenously every 2 weeks with expansion cohorts in programmed cell death protein 1 (PD-1)/programmed death-ligand 1(PD-L1)-naïve melanoma, renal cell carcinoma (RCC), microsatellite stable colorectal cancer (CRC), and ovarian cancer. The primary objective was to determine maximum tolerated dose (MTD) and recommended dose of the combination. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Exploratory objectives included correlation of clinical efficacy with tumor and peripheral immune population densities.ResultsOverall, 33 patients were enrolled during dose escalation (n=3) and dose expansion (n=30). No dose-limiting toxicities were reported in the initial dose level. Ziv-aflibercept 4 mg/kg plus pembrolizumab 2 mg/kg every 2 weeks was established as the MTD. Grade ≥3 adverse events occurred in 19/33 patients (58%), the most common being hypertension (36%) and proteinuria (18%). ORR in the dose-expansion cohort was 16.7% (5/30, 90% CI 7% to 32%). Complete responses occurred in melanoma (n=2); partial responses occurred in RCC (n=1), mesothelioma (n=1), and melanoma (n=1). Median OS was as follows: melanoma, not reached (NR); RCC, 15.7 months (90% CI 2.5 to 15.7); CRC, 3.3 months (90% CI 0.6 to 3.4); ovarian, 12.5 months (90% CI 3.8 to 13.6); other solid tumors, NR. Activated tumor-infiltrating CD8 T cells at baseline (CD8+PD1+), high CD40L expression, and increased peripheral memory CD8 T cells correlated with clinical response.ConclusionThe combination of ziv-aflibercept and pembrolizumab demonstrated an acceptable safety profile with antitumor activity in solid tumors. The combination is currently being studied in sarcoma and anti-PD-1-resistant melanoma.Trial registration numberNCT02298959.

115 Background: To mitigate the risks of chemotherapy associated neutropenia, during the COVID-19 pandemic, all genitourinary (GU) cancer patients treated with chemotherapy at the Princess Margaret Cancer Centre (PMCC) were offered primary prophylaxis with GCSF. We hypothesize that this reduced rates of febrile neutropenia, hospitalizations, healthcare costs and improved overall outcomes, compared to GU cancer patients treated with chemotherapy without GCSF in the 2 years prior to the pandemic. Methods: We performed a retrospective review of GU cancer patients, receiving curative or palliative intent chemotherapy, with or without primary GCSF prophylaxis between January 2018 and June 2022. GCSF was given either as a single dose or as consecutive doses post chemotherapy. Main outcomes were incidence of febrile neutropenia, hospitalization, health care expenditures as well as disease specific outcomes. Results: Overall, 248 patients with prostate cancer (44%), urothelial cancers (33%) germ cell (21%), and rare GU cancers (4%) were identified. Median age was 70 (range 19-91), 92% were male, 65% were ECOG 0/1. Treatment intent was neoadjuvant (13%), adjuvant (20%), or palliative (67%). Main regimens used were docetaxel, cabazitaxel, carboplatin, cisplatin/etoposide, gemcitabine/cisplatin and BEP. Median follow-up was 10.5 months (0.23-52.3 months). A total of 206/248 received primary GCSF prophylaxis. During chemotherapy, the median white blood cell levels were higher in the GCSF group compared to the non-GCSF group (14.1*10*9/L vs 2.90*10*9/L, p

BackgroundAngiogenic factors play a role in regulating immune suppression in the tumor microenvironment and driving resistance to immune checkpoint inhibitor therapy.1 Ziv-aflibercept is a soluble decoy receptor that ”traps” endogenous vascular endothelial growth factor (VEGF) with 100-fold increased binding affinity compared to Bevacizumab.2 The combination of ziv-aflibercept with either cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) or programmed cell death protein 1 (PD-1) blockade has shown promising antitumor efficacy in mouse models.3 4 We hypothesized that a novel combination of ziv-aflibercept and anti-PD-1 would be tolerable and lead to clinical benefits in tumors that traditionally do not respond to checkpoint blockade.MethodsThis is a multicenter phase 1B dose escalation study (NCT02298959) of the combination of ziv-aflibercept (at 2–4 mg/kg) plus pembrolizumab (at 2 mg/kg) administered intravenously every 2 weeks with expansion cohorts in PD-1/PD-L1 naïve melanoma, renal cell carcinoma (RCC), microsatellite stable colorectal cancer (MSS CRC), and ovarian cancer (figure 1). The primary objective was to determine the maximum tolerated dose (MTD) and recommended dose of the combination. Secondary endpoints included overall response rate (ORR) and overall survival (OS). Exploratory objectives included correlation of clinical efficacy and immune population densities in the tissue and periphery.ResultsOverall, 33 patients were enrolled during dose escalation (n=3) and dose expansion (n=30). No dose-limiting toxicities (DLTs) were reported in the initial dose level. Ziv-aflibercept 4 mg/kg plus pembrolizumab 2 mg/kg every 2 weeks was established as the MTD. Grade ≥3 treatment-related adverse events occurred in 19/33 patients (58%), the most common being hypertension (36%) and proteinuria (18%). ORR in the dose expansion cohort was 16.7% (5/30; 95% CI, 7–32%). Complete responses occurred in melanoma (n=2), partial responses occurred in RCC (n=1), mesothelioma (n=1), and melanoma (n=1). Efficacy outcomes by tumor type are shown in table 1 and figure 2. Median OS was as follows: melanoma, not reached; RCC, 15.7 months (90% CI, 2.5–15.7); CRC, 3.3 months (90% CI, 0.6–3.4), ovarian, 12.5 months (90% CI, 3.8–13.6), other solid tumors, not reached (figure 3). Activated tumor infiltrating CD8 T cells at baseline (CD8+PD1+), high CD40L expression (figure 4), and increased memory CD8 T cells in the periphery (figure 5) correlated with clinical response to the combination therapy.Abstract 374 Figure 1Study Schema of dose escalation and dose expansion. (A) Cohort 1 included the following tumors: clear cell sarcoma, triple negative breast cancer (TNBC), and mesothelioma. (B) Other solid tumors in Cohort 2 were: epithelioid mesothelioma (2) and TNBC (1).Abstract 374 Table 1Efficacy outcomes by dose level and tumor typea. Solid tumors included clear cell sarcoma (1), breast cancer (2), mesothelioma (3).b. Both patients with CR had melanoma and were in Cohort 2 (DL2).Abstract 374 Figure 2Waterfall plot of best RECIST response. Waterfall plot of maximum change from baseline in sum of target lesions for 28 patients with tumor measurements over time. Plot is color-coded by tumor type. Triangles indicate patients who developed new lesions, yellow circles indicate the 3 patients who received DL1.Abstract 374 Figure 3Progression and overall survival by tumor type. Kaplan-Meier curves for (A) progression-free survival and (B) overall survival based on tumor type.Abstract 374 Figure 4Luminex assay analysis of clinical response. Luminex analysis of baseline biomarkers. Patients were analyzed by clinical response (complete response [CR] and partial response [PR]) and durable clinical benefit (DCB) which includes patients with CR, PR, and stable disease (SD). (A) Baseline levels of IL-6 were lower in responders vs. non-responders (median 2.605 vs. 9.847 pg/mL, p = 0.009). Baseline CD40L was increased in responders (median 2,840 vs. 2,267 pg/mL, p = 0.06). (B) Baseline levels of GroB (median 1,272 vs. 592 pg/mL, p = 0.006), CXCL5 (median 547.5 vs. 296.2 pg/mL, p = 0.02), and CD40L (median 2,807 vs. 1,595 pg/mL, p = 0.001) were higher in patients with DCB vs. no DCB. P-values for baseline comparisons were obtained through Wilcoxon rank-sum test. The solid black line indicates median. Violins show range and kernel density estimate distributions of each group. (*) p < 0.05, (**) p < 0.01.Abstract 374 Figure 5Flow cytometry analysis. Flow cytometry analysis comparing T cell populations and monocytes between patients with clinical response (CR or PR, n = 5) and non-responders (n = 18) and patients with disease control (CR, PR, or SD, n = 12) and no disease control (n = 11). (A) CD4+ populations were increased in responders vs. non-responders at all time points. (B) CD8+ populations were decreased in responders vs. non-responders at all time points. (C) Treg CD4+/CD25+/FoxP3+ was decreased at baseline in responders. (D) Treg CD4+/CD25+/FoxP3+ were decreased at baseline and 1-month in patients with disease control vs. no disease control. (E) TCM CD8+/CD45RO+/CCR7+ was increased at all time points in responders vs. non-responders. (F) TEMRA CD8+/CD45RO-/CCR7- was decreased in responders at baseline. (G) Non-classical TIE2 was increased at baseline in non-responders. (H) Classical monocytes were increased at all time points in non-responders.ConclusionsThe combination of ziv-aflibercept and pembrolizumab demonstrated an acceptable safety profile with antitumor activity in solid tumors. The combination is currently being studied in sarcoma and anti-PD-1 resistant melanoma.AcknowledgementsThis trial was supported by the National Cancer Institute (NCI) and by Merck, Sharpe, and Dohme and Sanofi via Cooperative Research and Development Agreements with the NCI. PLB was supported by NCI UM1 Grant CA186644.Trial RegistrationNCT02298959ReferencesRahma OE, Hodi FS. The intersection between tumor angiogenesis and immune suppression. Clin Cancer Res September 15 2019;25(18):5449–5457. doi:10.1158/1078-0432.CCR-18-1543Holash J, Davis S, Papadopoulos N, et al. VEGF-trap: a VEGF blocker with potent antitumor effects. Proceedings of the National Academy of Sciences 2002;99(17):11393–11398. doi:10.1073/pnas.172398299Burova E, Ioffe E, Taduriyasas C, et al. Abstract 5035: blockade of VEGF with ziv-aflibercept (VEGF Trap) enhances anti-tumor efficacy of CTLA-4 blocking antibody in an Fc dependent manner. Cancer Research 2014;74(19 Supplement):5035–5035. doi:10.1158/1538-7445.am2014-5035Di Tacchio M, Macas J, Weissenberger J, et al. Tumor vessel normalization, immunostimulatory reprogramming, and improved survival in glioblastoma with combined inhibition of PD-1, angiopoietin-2, and VEGF. Cancer Immunology Research 2019;7(12):1910–1927. doi:10.1158/2326-6066.cir-18-0865Ethics ApprovalThis trial (NCT02298959) was approved by all participating IRBs.

Background Minimal qualitative data exist on the experiences of cancer patients treated with immune checkpoint inhibitors or costimulatory antibodies. Understanding the day to day experiences of patients being treated with immune checkpoint modulators, and how these relate to their health‐related quality of life, can inform future research and lead to better clinical decision‐making and care. We report here the first in depth qualitative study to consider patients' diverse and complex experiences with immune checkpoint modulators, with a focus on side effects and how these impact daily life. Methods This single‐center qualitative study was based on focus groups and semistructured interviews. Patients who were being treated or who had been treated with immune checkpoint modulators within the last year for a range of cancer diagnoses were recruited. Interpretive description informed our inductive, iterative approach to analysis. Results Eight themes were identified, characterizing the complexity of these patients' lived experiences: major categories of side effects experienced and how they impacted patient well‐being; the heterogeneous nature of side effects experienced; living with uncertainty; reframing the meaning and severity of SEs; focus on survival, hope, and being positive; acceptance and adaptation; feeling supported; and faith in medical innovation. Throughout their accounts, participants highlighted the profound impact that immune checkpoint modulators had on their daily lives. Conclusion This is the first in‐depth qualitative study into patient accounts of their experiences of treatment with immune checkpoint modulators, related side effects, and how it impacted their daily lives. This research is an integral initial step in developing an instrument that will assess treatment‐related side effects in patients treated with this form of therapy., This is the first report of patients' accounts of their experiences with ICM treatment, related SEs, and its impact on daily life. This research is an integral initial step in the development of an instrument that will measure treatment‐related SEs in patients treated with ICMs.

Background: Dysregulation of the PI3K/AKT/mTOR signaling pathway occurs in solid tumor malignancies. GDC-0077 (G) is a potent p110α-selective, p110α-mutant degrading inhibitor with anti-tumor activity in PIK3CA-mutant breast cancer xenograft models as a single agent and in combination with endocrine therapies (ET) with or without a CDK4/6 inhibitor (i). An open-label, Phase I dose escalation study of Galone and in combination with ET and P is underway in patients (pts) with locally advanced or metastatic PIK3CA-mutant solid tumors. Data from the combinations of G and L with and without P in pts with PIK3CA-mutant HR+/HER2- breast cancer are presented herein. Methods: This study (NCT03006172) assesses the safety (NCI-CTCAE v4), pharmacokinetics (PK), and preliminary anti-tumor activity (RECIST v1.1) of G administered daily (QD) orally at 6 or 9 mg with L (G+L) or at 3, 6, or 9 mg in combination with P+L (G+P+L). L is administered QD orally at 2.5 mg. P is administered QD orally at 125 mg on Days 1-21 followed by 7 days off in 28-day cycles. For dose expansion, prior CDK4/6i was prohibited (G+P+L) and up to one prior metastatic chemotherapy allowed (G+L and G+P+L). Tumor and ctDNA samples (collected before and after 2 weeks of G) are profiled for relevant signaling and pharmacodynamic (PD) biomarkers. Results: As of 29 March 2019, 70 pts had enrolled (G+L: 37 pts [7 at 6 mg and 30 at 9 mg]; G+P+L: 33 pts [3 at 3 mg, 3 at 6 mg, and 27 at 9 mg]). Overall, 33 pts in G+L and 31 pts in G+P+L received ≥ 1 prior metastatic therapy; 70% and 21% of pts received prior CDK4/6i in G+L and G+P+L arms, respectively. No DLTs were reported in pts receiving either combination with G. In G+L, the most frequent treatment-related AEs (TRAEs) occurring in ≥10 (27%) pts included hyperglycemia (25 pts, 68%), nausea (14 pts, 38%), and diarrhea (10 pts, 27%). Grade ≥3 TRAEs in ≥2 (5%) pts included hyperglycemia (7 pts, 19%), and fatigue and hypokalemia (2 pts each, 5%). In G+P+L, the most frequent TRAEs occurring in ≥13 (41%) pts included neutropenia (25 pts, 78%), hyperglycemia (17 pts, 52%), anemia (17 pts, 52%), diarrhea (16 pts, 49%), and nausea and thrombocytopenia (13 pts each, 39%). Grade ≥3 TRAEs in ≥2 (6%) pts included neutropenia (21 pts, 64%), hyperglycemia (5 pts, 15%), lymphopenia (3 pts, 15%), and leukopenia and thrombocytopenia (2 pts each, 6%). Hyperglycemia was manageable with oral anti-hyperglycemic medication. Stomatitis (grouped term) occurred in 11 pts (30%) in G+L and 21 pts (64%) in G+P+L and responded to treatment with dexamethasone mouthwash. 46 pts discontinued treatment, mainly due to disease progression; one due to Grade 3 hyperglycemia in G+P+L (no discontinuation due to AE in G+L). Median G treatment duration: 5.7 months (range 0.2-14.5) in G+L and 9.7 months (range 1.3-23.1) in G+P+L, with a cumulative G dose intensity of 98% for both. In G+ L, PR was reported in 6 pts (16%), confirmed PR in 3 pts (8%) and CBR 35% (13 pts). In G+P+L, PR was reported in 14 pts (42%), confirmed PR in 12 pts (36%) and CBR 76% (25 pts). G PK parameters were similar to those observed as a single agent, and P and L showed exposures comparable with historical data, suggesting an absence of PK drug-drug interaction (DDI). Robust PD downregulation of PI3K pathway effectors (pAKT, pS6) was observed in available paired biopsies and PIK3CA mutant allele frequency decreased in ctDNA on-treatment in most patients. Conclusion: This Phase Ib study of GDC-0077 in combination with letrozole with and without pabocicilb demonstrated a manageable safety profile combining GDC-0077 at its single agent recommended Phase II dose of 9 mg with letrozole with and without palbociclib at standard doses, with no evidence for DDI, high GDC-0077 dose intensity, and promising preliminary anti-tumor activity. Citation Format: Komal Jhaveri, Kevin Kalinsky, Philippe Bedard, Andres Cervantes, Cristina Saura, Ian Krop, Erika Hamilton, Peter Schmid, Andrea Varga, Nick Turner, Antoine Italiano, Valentina Gambardella, Zachary Veitch, Mafalda Oliveira, Leslie Dickmann, Naoki Kotani, Amy Kapp, Katie Hutchinson, Stephanie Royer-Joo, Anjali Vaze, Jennifer Schutzman, Dejan Juric. A phase Ib dose escalation study evaluating the mutant selective PI3K-alpha inhibitor GDC-0077 (G) in combination with letrozole (L) with and without palbociclib (P) in patients with PIK3CA-mutant HR+/HER2- breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-19-46.

Background: Activating mutations in PIK3CA, encoding the p110α subunit of phosphatidylinositol 3-kinase (PI3K), are highly prevalent in breast cancer and solid tumor malignancies. GDC-0077 is a potent p110α-selective inhibitor with a novel mechanism of action that degrades mutant p110α and anti-tumor activity in PIK3CA-mutant breast cancer xenograft models as a single agent and in combination with anti-estrogens with or without a CDK4/6 inhibitor. An open-label, Phase I dose-escalation study of GDC-0077 monotherapy and GDC-0077 combined with endocrine therapies and palbociclib is underway in patients (pts) with locally advanced or metastatic PIK3CA-mutant solid tumors. Data from the completed single agent dose escalation portion of the trial are presented herein. Methods: This study (NCT03006172) assesses the safety (NCI-CTCAE v4), pharmacokinetics (PK), and preliminary anti-tumor activity (RECIST v1.1) of single agent GDC-0077 administered daily (QD) orally at 6, 9, or 12 mg in 28-day cycles until intolerable toxicity or disease progression. Tumor and ctDNA samples are profiled for relevant signaling and pharmacodynamic (PD) biomarkers. Results: As of the clinical cut-off date of 29 March 2019, 20 pts were enrolled in the single agent arm, all with hormone receptor-positive breast cancer, except for 1 pt with colorectal cancer. Nineteen patients had received ≥ 2 prior lines of therapy for metastatic disease. GDC-0077 MTD was established at 9 mg QD. DLTs occurred in 2 pts at 12 mg (1 Grade 4 hyperglycemia, 1 Grade 3 fatigue). Adverse events (AEs) resulted in dose reduction in 6 pts (30%). The most frequent treatment-related (TR)AEs in ≥ 3 pts (15%) included hyperglycemia (14 pts, 70%), diarrhea (8 pts, 40%), decreased appetite and vomiting (4 pts each, 20%), and alopecia, fatigue, nausea, and weight decreased (3 pts each, 15%). Grade ≥3 TRAEs were hyperglycemia (4 pts, 20%) and lymphopenia, fatigue, nausea, weight loss, and asthenia (1 pt, 5% each). Hyperglycemia was generally manageable with oral anti-hyperglycemic medications. Stomatitis (grouped term) occurred in 4 pts (20%, all Grade 1) and responded to topical corticosteroid treatment. Rash (grouped term) occurred in 3 pts (15%) (1 unrelated Grade 2, otherwise Grade 1). No colitis was reported. Mean half-life (t1/2) of GDC-0077 was 18 hours, with the maximum concentration (Cmax) achieved 2-8 hours after dosing. The preliminary PK profile of GDC-0077 showed low-moderate variability in Cmax and area under the concentration-time curve, and dose proportionality across the tested dose levels. Accumulation with QD dosing regimen was 1.6-2.4 fold. All pts discontinued from treatment due to disease progression (radiographic or clinical). Median GDC-0077 treatment duration was 5.3 months (range 1.1-17.6) and cumulative dose intensity was 97%. Overall, partial response (PR) was observed in 5 pts (25%, range 2-10 lines of prior metastatic therapy), with confirmed PR in 4 pts (20%). The clinical benefit rate was 45% (9 of 20 pts). Decreased PI3K pathway effector expression in paired tumor biopsies and decreased PIK3CA mutant allele frequency were observed over time in the majority of specimens. In addition, 18F-fluorodeoxyglucose-positron emission tomography scans at baseline and after 2 weeks of GDC-0077 showed metabolic responses at all dose levels evaluated. Conclusion: The single agent dose escalation study of the p110α-selective and mutant-degrading inhibitor GDC-0077 demonstrated linear PK, a manageable safety profile, PD modulation of the PI3K pathway, and promising preliminary anti-tumor activity. GDC-0077 at the recommended Phase II dose of 9 mg in combination with endocrine therapies with or without the CDK4/6 inhibitor palbociclib is being investigated in this Phase I study and presented separately. Citation Format: Dejan Juric, Kevin Kalinsky, Mafalda Oliveira, Andres Cervantes, Philippe Bedard, Ian Krop, Erika Hamilton, Peter Schmid, Andrea Varga, Nick Turner, Antoine Italiano, Cristina Saura, Valentina Gambardella, Zachary Veitch, Leslie Dickmann, Naoki Kotani, Jill Fredrickson, Amy Kapp, Katie Hutchinson, Stephanie Royer-Joo, Anjali Vaze, Jennifer Schutzman, Komal Jhaveri. A first-in-human phase Ia dose escalation study of GDC-0077, a p110a-selective and mutant-degrading PI3K inhibitor, in patients with PIK3CA-mutant solid tumors [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr OT1-08-04.

Background Patients with cancer who are treated with immune checkpoint modulators (ICMs) have their health-related quality of life (HRQOL) measured using general patient-reported outcome (PRO) tools. To the authors' knowledge, no instrument has been developed to date specifically for patients treated with ICMs. The objective of the current study was to develop a toxicity subscale PRO instrument for patients treated with ICMs to assess HRQOL. Methods Input was collected from a systematic review as well as patients and physicians experienced with ICM treatment. Descriptive thematic analysis was used to evaluate the qualitative data obtained from patient focus groups and interviews, which informed an initial list of items that described ICM side effects and their impact on HRQOL. These inputs informed item generation and/or reduction to develop a toxicity subscale. Results Focus groups and individual interviews with 37 ICM-treated patients generated an initial list of 176 items. After a first round of item reduction that produced a shortened list of 76 items, 16 physicians who care for patients who are treated with ICMs were surveyed with a list of 49 patient-reported side effects and 11 physicians participated in follow-up interviews. A second round of item reduction was informed by the physician responses to produce a list of 25 items. Conclusions To the authors' knowledge, this 25-item list is the first HRQOL-focused toxicity subscale for patients treated with ICMs and was developed in accordance with US Food and Drug Administration guidelines, which prioritize patient input in developing PRO tools. The subscale will be combined with the Functional Assessment of Cancer Therapy-General (FACT-G) to form the FACT-ICM. Prior to recommending the formal use of this PRO instrument, the authors will evaluate its validity and reliability in longitudinal studies involving substantially more patients.

Background Metastatic germ cell tumor (mGCT) patients receiving chemotherapy have increased risk of life‐threatening venous thromboembolism (VTE). Identifying VTE risk factors may guide thromboprophylaxis in this highly curable population. Methods Data were collected from mGCT patients receiving first‐line platinum‐based chemotherapy at 22 centers. Predefined variables included International Germ Cell Cancer Collaborative Group (IGCCCG) risk classification, long‐axis diameter of largest retroperitoneal lymph node (RPLN), Khorana score, and use of indwelling vascular access device (VAD). VTE occurring at baseline, during chemotherapy and within 90 days, was analyzed. Results Data from 1135 patients were collected. Median age was 31 years (range 10‐74). IGCCCG risk was 64% good, 20% intermediate, and 16% poor. VTE occurred in 150 (13%) patients. RPLN >3.5 cm demonstrated highest discriminatory accuracy for VTE (AUC 0.632, P, Venous thromboembolism can cause morbidity in germ cell tumor patients receiving chemotherapy; large retroperitoneal lymphadenopathy (RPLN) and indwelling vascular access devices (VAD) are significant VTE risk factors. VAD insertion should be avoided and thromboprophylaxis can be considered for large RPLN.

Some patients who participate in early phase cancer trials enroll to more than one trial. Whether these patients have different characteristics or outcomes than patients who enroll to a single phase I trial is unknown. The study included all patients who participated in the solid tumor drug development program of the Princess Margaret Cancer Centre, a specialized academic cancer center, from July 2014 to January 2017. Patients sequentially enrolled to multiple phase I trials were compared to those enrolled in a single trial according to demographics, clinical characteristics, reported toxicities and prognosis. The study cohort included 328 patients, including 61 (19%) enrolled to multiple phase I trials and 267 (81%) enrolled to a single phase I trial. Demographics, comorbidities, performance status, cancer site and time between initial diagnosis and initial enrollment to the phase I program were comparable between both groups. Patients enrolled to multiple phase I trials received more previous non-trial treatment lines (median 3 versus 2, p

PURPOSE Active surveillance (AS) for testicular nonseminomatous germ cell tumors (NSGCT) is widely used. Although there is no consensus for optimal treatment at relapse on surveillance, globally patients typically receive chemotherapy. We describe treatment of relapses in our non–risk-adapted NSGCT AS cohort and highlight selective use of primary retroperitoneal lymph node dissection (RPLND). METHODS From December 1980 to December 2015, 580 patients with clinical stage I NSGCT were treated with AS, and 162 subsequently relapsed. First-line treatment was based on relapse site and extent. Logistic regression was used to explore factors associated with need for multimodal therapy on AS relapse. RESULTS Median time to relapse was 7.4 months. The majority of relapses were confined to the retroperitoneum (66%). After relapse, first-line treatment was chemotherapy for 95 (58.6%) and RPLND for 62 (38.3%), and five patients (3.1%) underwent other therapy. In 103 (65.6%), only one modality of treatment was required: chemotherapy only in 58 of 95 (61%) and RPLND only in 45 of 62 (73%). Factors associated with multimodal relapse therapy were larger node size (odds ratio, 2.68; P = .045) in patients undergoing chemotherapy and elevated tumor markers (odds ratio, 6.05; P = .008) in patients undergoing RPLND. When RPLND was performed with normal markers, 82% required no further treatment. Second relapse occurred in 30 of 162 patients (18.5%). With median follow-up of 7.6 years, there were five deaths (3.1% of AS relapses, but 0.8% of whole AS cohort) from NSGCT or treatment complications. CONCLUSION The retroperitoneum is the most common site of relapse in clinical stage I NSGCT on AS. Most are cured by single-modality treatment. RPLND should be considered for relapsed patients, especially those with disease limited to the retroperitoneum and normal markers, as an option to avoid chemotherapy.

Background CFI-400945 is a first-in-class oral inhibitor of polo-like kinase 4 (PLK4) that regulates centriole duplication. Primary objectives of this first-in-human phase 1 trial were to establish the safety and tolerability of CFI-400945 in patients with advanced solid tumours. Secondary objectives included pharmacokinetics, pharmacodynamics, efficacy, and recommended phase 2 dose (RP2D). Methods Continuous daily oral dosing of CFI-400945 was evaluated using a 3+3 design guided by incidence of dose-limiting toxicities (DLTs) in the first 28-day cycle. Safety was assessed by CTCAE v4.0. ORR and CBR were evaluated using RECIST v1.1. Results Forty-three patients were treated in dose escalation from 3 to 96 mg/day, and 9 were treated in 64 mg dose expansion. After DLT occurred at 96 and 72 mg, 64 mg was established as the RP2D. Neutropenia was a common high-grade (19%) treatment-related adverse event at ≥ 64 mg. Half-life of CFI-400945 was 9 h, with Cmax achieved 2–4 h following dosing. One PR (45 cycles, ongoing) and two SD ≥ 6 months were observed (ORR = 2%; CBR = 6%). Conclusions CFI-400945 is well tolerated at 64 mg with dose-dependent neutropenia. Favourable pharmacokinetic profiles were achieved with daily dosing. Response rates were low without biomarker pre-selection. Disease-specific and combination studies are ongoing. Trial Registration Clinical Trials Registration Number – NCT01954316 (Oct 1st, 2013)

BackgroundGWN323 is an IgG1 monoclonal antibody (mAb) against the glucocorticoid-induced tumor necrosis factor receptor-related protein. This first-in-human, open-label phase I/Ib study aimed to investigate the safety and tolerability and to identify the recommended doses of GWN323 with/without spartalizumab, an anti-programmed cell death receptor-1 agent, for future studies. Pharmacokinetics, preliminary efficacy and efficacy biomarkers were also assessed.MethodsPatients (aged ≥18 years) with advanced/metastatic solid tumors with Eastern Cooperative Oncology Group performance status of ≤2 were included. GWN323 (10–1500 mg) or GWN323+spartalizumab (GWN323 10–750 mg+spartalizumab 100–300 mg) were administered intravenously at various dose levels and schedules during the dose-escalation phase. Dose-limiting toxicities (DLTs) were assessed during the first 21 days in a single-agent arm and 42 days in a combination arm. Adverse events (AEs) were graded per National Cancer Institute-Common Toxicity Criteria for Adverse Events V.4.03 and efficacy was assessed using Response Evaluation Criteria in Solid Tumors V.1.1.ResultsOverall, 92 patients (single-agent, n=39; combination, n=53) were included. The maximum administered doses (MADs) in the single-agent and combination arms were GWN323 1500 mg every 3 weeks (q3w) and GWN323 750 mg+spartalizumab 300 mg q3w, respectively. No DLTs were observed with single-agent treatment. Three DLTs (6%, all grade ≥3) were noted with combination treatment: blood creatine phosphokinase increase, respiratory failure and small intestinal obstruction. Serious AEs were reported in 30.8% and 34.0%, and drug-related AEs were reported in 82.1% and 77.4% of patients with single-agent and combination treatments, respectively. Disease was stable in 7 patients and progressed in 26 patients with single-agent treatment. In combination arm patients, 1 had complete response (endometrial cancer); 3, partial response (rectal cancer, adenocarcinoma of colon and melanoma); 14, stable disease; and 27, disease progression. GWN323 exhibited a pharmacokinetic profile typical of mAbs with a dose-dependent increase in the pharmacokinetic exposure. Inconsistent decreases in regulatory T cells and increases in CD8+ T cells were observed in the combination arm. Gene expression analyses showed no significant effect of GWN323 on interferon-γ or natural killer-cell signatures.ConclusionsGWN323, as a single agent and in combination, was well tolerated in patients with relapsed/refractory solid tumors. The MAD was 1500 mg q3w for single-agent and GWN323 750 mg+spartalizumab 300 mg q3w for combination treatments. Minimal single-agent activity and modest clinical benefit were observed with the spartalizumab combination.Trial registration numberNCT02740270.

Purpose:Sabatolimab (MBG453) and spartalizumab are mAbs that bind T-cell immunoglobulin domain and mucin domain-3 (TIM-3) and programmed death-1 (PD-1), respectively. This phase I/II study evaluated the safety and efficacy of sabatolimab, with or without spartalizumab, in patients with advanced solid tumors.Patients and Methods:Primary objectives of the phase I/Ib part were to characterize the safety and estimate recommended phase II dose (RP2D) for future studies. Dose escalation was guided by a Bayesian (hierarchical) logistic regression model. Sabatolimab was administered intravenously, 20 to 1,200 mg, every 2 or 4 weeks (Q2W or Q4W). Spartalizumab was administered intravenously, 80 to 400 mg, Q2W or Q4W.Results:Enrolled patients (n = 219) had a range of cancers, most commonly ovarian (17%) and colorectal cancer (7%); patients received sabatolimab (n = 133) or sabatolimab plus spartalizumab (n = 86). The MTD was not reached. The most common adverse event suspected to be treatment-related was fatigue (9%, sabatolimab; 15%, combination). No responses were seen with sabatolimab. Five patients receiving combination treatment had partial responses (6%; lasting 12–27 months) in colorectal cancer (n = 2), non–small cell lung cancer (NSCLC), malignant perianal melanoma, and SCLC. Of the five, two patients had elevated expression of immune markers in baseline biopsies; another three had >10% TIM-3–positive staining, including one patient with NSCLC who received prior PD-1 therapy.Conclusions:Sabatolimab plus spartalizumab was well tolerated and showed preliminary signs of antitumor activity. The RP2D for sabatolimab was selected as 800 mg Q4W (alternatively Q3W or Q2W schedules, based on modeling), with or without 400 mg spartalizumab Q4W.

Tumor cells that preferentially enter circulation include the precursors of metastatic cancer. Previously, we characterized circulating tumor cells (CTC) from patients with breast cancer and identified a signature of genomic regions with recurrent copy number gains. Through fluorescence in situ hybridization, we now show that these CTC-associated regions are detected within the matched untreated primary tumors of these patients (21-69%, median 55.5%, n=19). Furthermore, they are more prevalent in the metastases of patients who died from breast cancer after multiple rounds of treatment (70-100%, median 93%, n=41). Diversity indices revealed that higher spatial heterogeneity for these regions within primary tumors is associated with increased dissemination and metastasis. An identified subclone with multiple regions gained (MRG clone) was enriched in a post-treatment primary breast carcinoma as well as multiple metastatic tumors and local breast recurrences obtained at autopsy, indicative of a distinct early subclone with the capability to resist multiple lines of treatment and eventually cause death. Additionally, multiplex immunofluorescence revealed that tumor heterogeneity is significantly associated with the degree of infiltration of B lymphocytes in triple-negative breast cancer, a subtype with a large immune component. Collectively, these data reveal the functional potential of genetic subclones that comprise heterogeneous primary breast carcinomas and are selected for in CTCs and post-treatment breast cancer metastases. In addition, they uncover a relationship between tumor heterogeneity and host immune response in the tumor microenvironment.

Purpose: We wanted to determine the prognosis and the phenotypic characteristics of hormone receptor–positive advanced breast cancer tumors harboring an ERBB2 mutation in the absence of a HER2 amplification. Experimental Design: We retrospectively collected information from the American Association of Cancer Research-Genomics Evidence Neoplasia Information Exchange registry database from patients with hormone receptor–positive, HER2-negative, ERBB2-mutated advanced breast cancer. Phenotypic and co-mutational features, as well as response to treatment and outcome were compared with matched control cases ERBB2 wild type. Results: A total of 45 ERBB2-mutant cases were identified for 90 matched controls. The presence of an ERBB2 mutation was not associated with worse outcome determined by overall survival (OS) from first metastatic relapse. No significant differences were observed in phenotypic characteristics apart from higher lobular infiltrating subtype in the ERBB2-mutated group. ERBB2 mutation did not seem to have an impact in response to treatment or time-to-progression (TTP) to endocrine therapy compared with ERBB2 wild type. In the co-mutational analyses, CDH1 mutation was more frequent in the ERBB2-mutated group (FDR < 1). Although not significant, fewer co-occurring ESR1 mutations and more KRAS mutations were identified in the ERBB2-mutated group. Conclusions: ERBB2-activating mutation was not associated with a worse OS from time of first metastatic relapse, or differences in TTP on treatment as compared with a series of matched controls. Although not significant, differences in coexisting mutations (CDH1, ESR1, and KRAS) were noted between the ERBB2-mutated and the control group.

Background The correlation between blood-based tumor mutation burden (bTMB) and tissue-based tumor mutation burden(tTMB) has not been broadly tested in a multicancer cohort. Here, we assess the correlation between bTMB with tTMB in phase I trial patients treated with immunotherapy. As an exploratory analysis, we evaluated circulating tumor DNA (ctDNA) dynamics in responders. Methods Patients treated with immunotherapy at the Princess Margaret phase I trials unit were enrolled. Pretreatment plasma ctDNA and matched normal blood controls were collected. Available archival tissue formalin-fixed paraffin-embedded (FFPE) samples were analyzed. A 425-gene panel was used to sequence both ctDNA and FFPE samples. Samples with TMB within the highest tertile were considered as high TMB. Results Thirty-eight patients were accrued from 25 different trials, 86.8% of which involved an anti-PD-1/PD-L1 agent. Thirty patients (78.9%) had detectable mutations in ctDNA, of which the median (range) bTMB was 5 (1-53) mutations per megabase (mut/Mb). Of the 22 patients with available FFPE samples, mutations were detected in 21 (95.4%); the median (range) tTMB was 6 (2-124) mut/Mb. Among the 16 patients with detectable mutations in both FFPE and ctDNA, a statistically significant correlation between bTMB and tTMB was observed (ρ = 0.71; P = .002). High TMB was not associated with better survival. All 3 responders had a decrease in the variant allele frequency of mutations detected in ctDNA at a second timepoint relative to baseline, indicating a potential early marker of response. Conclusions In this small series, bTMB correlated with tTMB. An on-treatment decrease in VAF of mutations detected in ctDNA at baseline was observed in responders. Larger studies to verify our findings are warranted.

Background Human leukocyte antigen class 1 (HLA-1)–dependent immune activity is linked to autoimmune diseases. HLA-1–dependent CD8+ T cells are required for immune checkpoint blockade antitumor activity. It is unknown if HLA-1 genotype is predictive of toxicity to immune checkpoint blockade. Methods Patients with advanced solid tumors stratified into 5 cohorts received single agent pembrolizumab (anti-programmed cell death-1) 200 mg intravenously every 3 weeks in an investigator-initiated phase II trial (Investigator-Initiated Phase II Study of Pembrolizumab Immunological Response Evaluation study, NCT02644369). Germline whole-exome sequencing of peripheral blood mononuclear cells was performed using the Illumina HiSeq2500 platform. HLA-1 haplotypes were predicted from whole-exome sequencing using HLAminer and HLAVBSeq. Heterozygosity of HLA-A, -B, and -C, individual HLA-1 alleles, and HLA haplotype dimorphism at positions −21 M and −21 T of the HLA-A and -B leader sequence were analyzed as predictors of toxicity defined as grade 2 or greater immune-related adverse events and clinical benefit defined as complete or partial response, or stable disease for 6 or more cycles of pembrolizumab. Statistical significance tests were 2-sided. Results In the overall cohort of 101 patients, the frequency of toxicity and clinical benefit from pembrolizumab was 22.8% and 25.7%, respectively. There was no association between any of the HLA-1 loci or alleles with toxicity. HLA-C heterozygosity had an association with decreased clinical benefit relative to HLA-C homozygosity when controlling for cohort (odds ratio = 0.28, 95% confidence interval = 0.09 to 0.91, P = .04). HLA-A and -B haplotype −21 M/T dimorphism and heterozygosity of HLA-A, -B, and -C were not predictive of outcomes. Conclusions HLA-C heterozygosity may predict decreased response to pembrolizumab. Prospective validation is required.

PurposeTo evaluate whether administration of the oral DNA hypomethylating agent CC-486 enhances the poor response rate of immunologically ‘cold’ solid tumors to immune checkpoint inhibitor durvalumab.Experimental designPD-L1/PD-1 inhibitor naïve patients with advanced microsatellite stable colorectal cancer; platinum resistant ovarian cancer; and estrogen receptor positive, HER2 negative breast cancer were enrolled in this single-institution, investigator-initiated trial. Two 28 day regimens, regimen A (CC-486 300 mg QD Days 1–14 (cycles 1–3 only) in combination with durvalumab 1500 mg intravenous day 15) and regimen B (CC-486 100 mg QD days 1–21 (cycle 1 and beyond), vitamin C 500 mg once a day continuously and durvalumab 1500 mg intravenous day 15) were investigated. Patients underwent paired tumor biopsies and serial peripheral blood mononuclear cells (PBMCs) collection for immune-profiling, transcriptomic and epigenomic analyzes.ResultsA total of 28 patients were enrolled, 19 patients treated on regimen A and 9 on regimen B. The combination of CC-486 and durvalumab was tolerable. Regimen B, with a lower dose of CC-486 extended over a longer treatment course, showed less grade 3/4 adverse effects. Global LINE-1 methylation assessment of serial PBMCs and genome-wide DNA methylation profile in paired tumor biopsies demonstrated minimal changes in global methylation in both regimens. The lack of robust tumor DNA demethylation was accompanied by an absence of the expected ‘viral mimicry’ inflammatory response, and consequently, no clinical responses were observed. The disease control rate was 7.1%. The median progression-free survival was 1.9 months (95% CI 1.5 to 2.3) and median overall survival was 5 months (95% CI 4.5 to 10).ConclusionsThe evaluated treatment schedules of CC-486 in combination with durvalumab did not demonstrate robust pharmacodynamic or clinical activity in selected immunologically cold solid tumors. Lessons learned from this biomarker-rich study should inform continued drug development efforts using these agents.Trial registration numberNCT02811497.

BACKGROUND A subset of patients treated with immune checkpoint inhibitors experience an accelerated tumor growth rate (TGR) in comparison with pretreatment kinetics; this is known as hyperprogression. This study assessed the relation between hyperprogressive disease (HPD) and treatment-related toxicity and clinical factors. METHODS This study reviewed patients with solid tumors who were enrolled in early-phase immunotherapy trials at Princess Margaret Cancer Centre between August 2012 and September 2016 and had computed tomography scans in the pre-immunotherapy (reference) and on-immunotherapy (experimental) periods. HPD was defined as progression according to Response Evaluation Criteria in Solid Tumors 1.1 at the first on-treatment scan and a ≥2-fold increase in TGR between the reference and experimental periods. Treatment-related toxicities requiring systemic therapy, drug delays, or discontinuation were considered clinically significant adverse events (CSAEs). RESULTS Of 352 patients, 182 were eligible for analysis. The median age was 60 years, and 54% were male. The Eastern Cooperative Oncology Group performance status was 0 (32%) or 1 (68%). The Royal Marsden Hospital (RMH) prognostic score was 0/1 in 59%. Single-agent immunotherapy was given to 80% of the patients. Most patients (89%) received anti-programmed death (ligand) 1 antibodies alone or in combination with other therapies. HPD occurred in 12 of 182 patients (7%). A higher proportion of females was seen among HPD patients (P = .01), but no association with age, performance status, tumor type, RMH prognostic score, combination immunotherapy, or CSAEs was found. The 1-year overall survival rate was 28% for HPD patients and 53% for non-HPD patients (hazard ratio, 1.7; 95% confidence interval, 0.9-3.3; P = .11). CONCLUSIONS HPD was observed in 7% of patients with solid tumors treated with immunotherapy. HPD was not associated with CSAEs, age, tumor type, or the type of immunotherapy but was more common in females.

Background Immunotherapy (IO) agents can cause late-onset immune-related adverse events (irAEs). In phase I trials, observation for dose-limiting toxicities (DLTs) is typically limited to the first cycle. The incidence of delayed-onset DLTs and their potential impact on dose determination have not been fully elucidated. Patients and methods Consecutive patients enrolled in early phase IO trials at Princess Margaret Cancer Centre between August 2012 and September 2016 were retrospectively reviewed, applying trial-specific definitions for DLTs. A clinically significant AE (csAE) was defined as a treatment-related adverse event requiring corticosteroids, hormone replacement, IO delay or discontinuation. Results A total of 352 consecutive trial enrolments in 21 early phase clinical trials were included. Two-hundred seventy-eight patients (79%) received monotherapy and 74 (21%) received combination IO. Two hundred sixty (74%) patients experienced irAEs. There were two protocol-defined DLTs. Twenty (5.7%) patients had 24 csAEs qualifying as DLTs except for occurrence after the protocol-specified DLT period. One-hundred and six (10%) of irAEs were csAEs, including endocrine (26%), respiratory (14%), gastrointestinal (11%), general (10%), dermatological (8%), hepatic (8%), musculoskeletal (6%), pancreatic (6%), haematological, metabolic, neurological, cardiac (each 2%), infective and ocular (each 1%) events. The highest risk of first-onset csAE was during the first 4 weeks compared with the period from 4 weeks to end of treatment (odds ratio 3.13, 95% confidence interval 1.95–5.02). The median time to first onset csAE was significantly shorter with combination than monotherapy IO (32 vs. 146 days, P Conclusions In our series of early phase IO trials, the risk of csAE was highest during the initial 4 weeks on IO treatment, supporting the use of the conventional DLT period for dose escalation decision. However, there were 24 clinically significant late-onset DLTs in 5.7% of patients. Combination IO was associated with greater risk of and also earlier onset for csAE, which may need to be considered for early phase trial design.

Supplemental Digital Content is available in the text., Objectives: SLC-0111 is an ureido-substituted benzenesulfonamide small molecule inhibitor of carbonic anhydrase IX. The objectives of this first-in-human Phase 1 study were to determine the safety and tolerability of SLC-0111 in patients with advanced solid tumors and to establish the recommended Phase 2 dose for future clinical investigations. Materials and Methods: Using a 3+3 design, dose escalation started at 500 mg oral daily dosing of SLC-0111 in cohort 1 and increased to 1000 and 2000 mg in cohorts 2 and 3. Drug-related adverse events (AEs) were monitored to determine safety and tolerability. Pharmacokinetic analyses assessed plasma concentrations of single and repeated doses of SLC-0111. RECIST 1.1 criteria were used to assess disease progression. Results: No dose-limiting toxicities were reported and patients dosed at ≤1000 mg exhibited fewer drug-related AEs ≥ grade 3 and fewer AEs such as nausea and vomiting, compared with the 2000-mg cohort. Forty-one percent of patients experienced dose interruptions or discontinuation and the majority (71%) of these occurred in the 2000-mg cohort. Mean Cmax and AUC(0-24) values for single doses were similar at the 1000-mg and 2000-mg dose levels. Mean Tmax and T1/2 values of SLC-0111 were similar after single and repeated dosing. Power-law analysis of Cmax and AUC0-24 showed that exposure to SLC-0111 was generally dose proportional. No objective responses were observed, but stable disease >24 weeks was observed in 2 patients. Conclusions: SLC-0111 was safe in patients with previously treated, advanced solid tumors. The safety and pharmacokinetic data support 1000 mg/d as the recommended phase 2 dose for SLC-0111.

Background: The over-expression of CD73 has been linked to many cancers. NZV930, an investigational, CD73-targeting monoclonal antibody (mAb), forms bidentate structures with the CD73 dimer, shutting down the catalytic activity of cell surface and soluble CD73. Taminadenant is an investigational A2AR antagonist and spartalizumab is an anti-PD-1 mAb. Preclinical studies provide compelling antitumor activity when combining CD73, A2AR, and PD-1 blockade. Methods: This first-in-human study (NCT03549000) comprised dose-escalation and dose-expansion parts. Here, we present the dose-escalation results of the four treatment (tx) arms: NZV930 single agent (SA; 60-1000 mg Q2W), NZV930 (200-600 mg Q2W) + spartalizumab (400 mg Q4W) or taminadenant (80-240 mg Q2W), or in combination with spartalizumab (400 mg Q4W) + taminadenant (80-240 mg BID). Eligible pts had selected malignancies, and disease progression following standard therapy. Primary objectives included assessing safety and tolerability and determining the recommended dose for expansion (RDE) of NZV930 SA and its combinations. Secondary objectives were to determine efficacy, characterize the pharmacokinetics (PKs) of NZV930 SA and its combinations, and assess the immunogenicity of spartalizumab and NZV930. Biomarker tumor samples were obtained at screening, C2D1, and C4D1. Results: As of June 10, 2021, 105 pts were enrolled for dose escalation, including pts with CRC (n=63), ovarian cancer (n=15), pancreatic cancer (n=11), NSCLC (n=8), TNBC (n=5), RCC (n=2), and prostate cancer (n=1). Most pts (81%) had been treated with ≥3 lines of prior therapy. In total, 98 pts discontinued, mainly due to disease progression (72%); six were ongoing. At least one tx-related adverse event (TRAE) was reported by 89 pts (85%); these were mostly grade 1-2. A triad of headache, fever, and nausea/emesis was observed after the first infusion of NZV930. Most common TRAEs (≥30%) were headache (67%), nausea and vomiting (32% each), and pyrexia (30%). At least one grade ≥3 TRAE was reported in 15 pts (14%); headache (4%) was most common, accounting for 4/7 DLTs (all grade ≥3). There were no tx-related deaths. Overall, no responses were reported; 12 pts (11%) had stable disease and 69 pts (66%) had progressive disease. NZV930 has good PK properties, with target-mediated drug disposition at lower doses, which normalize to typical IgG-like PKs at higher doses. Biomarker data confirm CD73 target engagement in plasma. Adenosine pathway modulation in tumors and plasma was seen post-NZV930 tx. Conclusions: NZV930 reduced adenosine levels in plasma and tumors. The RDE of NZV930 SA or in combination with spartalizumab and/or taminadenant is 600 mg Q2W with a step-up dosing regimen. NZV930 SA and its combinations exhibited a tolerable safety profile in multiple advanced solid tumors and showed good PK properties. Citation Format: Siqing Fu, Udai Banerji, Philippe L. Bedard, Aitana Calvo Ferrándiz, Alberto Chiappori, Jayesh Desai, Rahima Jamal, Desamparados Roda Perez, Noboru Yamamoto, Erica Vieira, Gabrielle Wong, Kulandayan K. Subramanian, Shunguang Wang, Britta Mueller, Javier A. Otero, Si-Lin Koo. A phase I/Ib study of the safety and preliminary efficacy of NZV930 alone and in combination with spartalizumab and/or taminadenant in patients (pts) with advanced malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT503.

2589 Background: The molecular networks comprising circadian rhythm are expressed in immune cells where they affect immune-related processes. Within the emerging field of chrono-immunotherapy, it has been proposed that immunotherapies should be applied at certain times of day to optimize efficacy. Two recent reports have suggested that earlier administration of immune checkpoint inhibitors (ICIs) in non-small cell lung cancer and melanoma may offer improved survival outcomes (Karaboué et al. ASCO 2021, PMID 34780711). Whether this observation applies to other tumour types, or occurs in geographic regions with differing seasonality, is not known. Methods: We retrospectively analyzed the time of administration data from the INSPIRE single-centre, phase II, multi-cohort study of pembrolizumab (200 mg IV over 1 hour, q3w to maximum 35 cycles) in patients with advanced solid tumours (NCT02644369). Kaplan-Meier methods were used to estimate PFS and OS. Cox proportional hazards models were fitted to assess the association between time of administration and PFS or OS, adjusting for cohort. Fisher’s exact test was used to test for association with immune-related adverse events (irAEs). Results: A total of 106 patients (19 head and neck squamous cell, 22 triple negative breast, 21 epithelial ovarian, 12 melanoma, 32 other solid tumours) were accrued between March 21, 2016, and May 9, 2018. Median time of follow-up was 11.5 months. Start of infusion times were obtained for 806 total doses. The median time of administration was 15h06 for the first dose and 15h11 for all doses (range 09h19 – 18h34). No differences in PFS or OS were observed between patients who received their first dose before or after noon, or before or after 15h06. Furthermore, no differences in PFS or OS were observed between patients who received ≥ 50% of their doses before or after noon, or before or after 15h11. There was also no difference in PFS or OS between patients who did or did not have a significant proportion of doses (≥ 20%) after 16h30 (“evening” in previous reports). There were no differences in the frequency of grade ≥ 2 irAEs amongst the various groups. No differences in efficacy were found when individual cohorts were evaluated separately. Finally, no differences in PFS or OS were observed when participants were grouped by season of first dose. Conclusions: Despite previous reports of improved survival with earlier ICI dosing, we did not identify any association of time of pembrolizumab administration with clinical outcomes. Our analysis is limited by small sample size and patient heterogeneity which may hinder identification of smaller associations. It is also unclear whether lower response rates in a pan-cancer population (relative to prior reports in lung cancer and melanoma) might impact correlation analysis. Further studies will be necessary to interrogate this phenomenon and ensure that ICI are optimally applied.

2513 Background: BCA101 is a first-in-class bifunctional fusion protein consisting of an anti-EGFR monoclonal antibody (mAb) and TGFβ receptor 2 extracellular domain (TGFβRII-ECD). Herein, we report the safety, pharmacokinetic (PK), pharmacodynamic (PD), and preliminary efficacy data of BCA101 as monotherapy and in combination with pembrolizumab among patients (pts) with advanced solid tumors refractory to standard therapies. Methods: Pts received BCA101 as a single agent (SA) or in combination with pembrolizumab at escalating doses in a parallel 3+3 design starting at 64 mg intravenously (IV) weekly (qw); and at 240 mg IV qw with pembrolizumab 200 mg IV q3w. Primary endpoint: safety and tolerability (CTCAE v5.0); dose limiting toxicity (DLT) period: 21 days. Secondary endpoints: overall response rate (ORR), PK/PD profile, progression-free survival (PFS), and changes in plasma and intra-tumoral TGFβ signaling assessed by SMAD2 phosphorylation. Results: As of 08-Feb-2022, 60 pts have received BCA101 (part A). Forty-five pts (colorectal, n=14; pancreatic, n=7; head and neck squamous cell carcinoma [HNSCC], n=6) received SA BCA101 at doses up to 1500 mg IV weekly. Fifteen subjects (SCC of the anal canal [SCAC], n=8; HNSCC, n=7) received BCA101 doses ranging from 240 to 1500 mg IV qw in combination with pembrolizumab. Maximum tolerated dose has not been reached. Common adverse events (AEs) attributed to BCA101 include rash (70%), fatigue (23%), pruritis and epistaxis (17% each); all grade (G)2 or less. One DLT was observed at the 1250 mg SA dose (G3 anemia, hematuria). No drug-related G4 AEs or deaths were observed. At data cutoff, best response in the SA arm was stable disease (SD) in 15/39 (39%) evaluable pts. In combination, partial response (PR) was observed in 3/11 (27%) evaluable pts (2 in SCAC, 1 in HNSCC) and a disease control rate (DCR) of 9/11 (82%). Two of 3 responders have been on study >4 months; including 1 confirmed PR in a HNSCC pt refractory to anti-PD-1 therapy and cetuximab. Saturation of the EGFR target was observed at BCA101 doses ≥750 mg. Dose proportional increase in Cmax and AUC were observed with doses of BCA101 750-1500 mg. Prolonged neutralization of plasma TGFβ1 was achieved at all doses ≥500 mg. Among paired tumor biopsies (n=23), pSMAD2 reduction up to 62% was observed at doses ≥500 mg. Conclusions: BCA101 is well tolerated and clinically active as a SA and in combination with PD-1 blockade with a predictable PK/PD profile. A recommended dose of 1500 mg both as SA and in combination has advanced to the part B expansion phase for pts with HNSCC, SCAC, and cutaneous SCC. Clinical trial information: NCT04429542.