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PURPOSE Subset analyses from phase III evaluation of epidermal growth factor receptor inhibition (EGFRi) suggest improved outcomes in patients with EGFR-amplified gastroesophageal adenocarcinoma (GEA), but large-scale analyses are lacking. This multi-institutional analysis sought to determine the role of EGFRi in the largest cohort of patients with EGFR-amplified GEA to date. PATIENTS AND METHODS A total of 60 patients from 15 tertiary cancer centers in six countries met the inclusion criteria. These criteria required histologically confirmed GEA in the metastatic or unresectable setting with EGFR amplification identified by using a Clinical Laboratory Improvement Amendments–approved assay, and who received on- or off-protocol EGFRi. Testing could be by tissue next-generation sequencing, plasma circulating tumor DNA next-generation sequencing, and/or fluorescence in situ hybridization performed by a Clinical Laboratory Improvement Amendments approved laboratory. Treatment patterns and outcomes analysis was also performed using a deidentified clinicogenomic database (CGDB). RESULTS Sixty patients with EGFR-amplified GEA received EGFRi, including 31 of 60 patients (52%) with concurrent chemotherapy. Across treatment lines, patients achieved a 43% objective response rate with a median progression-free survival of 4.6 months (95% CI, 3.5 to 6.4). Patients receiving EGFRi in first-, second-, and third-line therapy achieved a median overall survival of 20.6 months (95% CI, 13.5 to not reached [NR]), 9 months (95% CI, 7.9 to NR), and 8.4 months (7.6 to NR), respectively. This survival far exceeded the 11.2-month (95% CI, 8.7 to 14.2) median overall survival from first-line initiation of non-EGFRi therapy in patients with EGFR-amplified GEA in the CGDB. Despite this benefit, analysis of the CGDB (January 2011-December 2020) suggests that only 5% of patients with EGFR-amplified GEA received EGFRi. CONCLUSION Patients with EGFR-amplified GEA derive significant benefit from EGFRi. Further prospective investigation of EGFRi in a well-selected patient population is ongoing in an upcoming trial of amivantamab in EGFR and/or MET amplified GEA.

Cutaneous metastases in pancreatic cancer (PC) are rare. Herein, we evaluate the clinical, genomic, and other descriptors of patients with PC and cutaneous metastases.Institutional databases were queried, and clinical history, demographics, PC cutaneous metastasis details, and overall survival (OS) from cutaneous metastasis diagnosis were abstracted. OS was estimated using Kaplan-Meier methods.Forty patients were identified, and median age (Q1-Q3, IQR) of PC diagnosis was 66.0 (59.3-72.3, 12.9) years. Most patients had Stage IV disease at diagnosis (n = 26, 65%). The most common location of the primary tumor was the tail of the pancreas (n = 17, 43%). The most common cutaneous metastasis site was the abdomen (n = 31, 78%), with umbilical lesions occurring in 74% (n = 23) of abdominal lesions. The median OS (95% CI) was 11.4 months (7.0, 20.4). Twenty-three patients had umbilical metastases (58%), and 17 patients had non-umbilical metastases (43%). The median OS (95% CI) was 13.7 (7.0, 28.7) months in patients with umbilical metastases and 8.9 (4.1, Not reached) months in patients with non-umbilical metastases (p = 0.1). Sixteen of 40 (40%) patients underwent somatic testing, and findings were consistent with known profiles. Germline testing in 12 (30%) patients identified pathogenic variants in patients: CHEK2, BRCA1, and ATM.Cutaneous metastases from PC most frequently arise from a pancreas tail primary site and most frequently occur in the umbilicus. Cutaneous metastases may generally be categorized as umbilical or non-umbilical metastases.

Background Hepatocellular carcinoma (HCC) patient‐derived xenograft (PDX) models hold potential to advance knowledge in HCC biology to help improve systemic therapies. Beside hepatitis B virus‐associated tumors, HCC is poorly established in PDX. Methods PDX formation from fresh HCC biopsies were obtained and implanted intrahepatically or in subrenal capsule (SRC). Mouse liver injury was induced in immunodeficient Fah−/− mice through cycling off nitisinone after HCC biopsy implantation, versus continuous nitisinone as non‐liver injury controls. Mice with macroscopically detectable PDX showed rising human alpha1‐antitrypsin (hAAT) serum levels, and conversely, no PDX was observed in mice with undetectable hAAT. Results Using rising hAAT as a marker for PDX formation, 20 PDX were established out of 45 HCC biopsy specimens (44%) reflecting the four major HCC etiologies most commonly identified at Memorial SloanKettering similar to many other institutions in the United States. PDX was established only in severely immunodeficient mice lacking lymphocytes and NK cells. Implantation under the renal capsule improved PDX formation two‐fold compared to intrahepatic implantation. Two out of 18 biopsies required murine liver injury to establish PDX, one associated with hepatitis C virus and one with alcoholic liver disease. PDX tumors were histologically comparable to biopsy specimens and 75% of PDX lines could be passaged. Conclusions Using cycling off nitisinone‐induced liver injury, HCC biopsies implanted under the renal capsule of severely immunodeficient mice formed PDX with 57% efficiency as determined by rising hAAT levels. These findings facilitate a more efficient make‐up of PDX for research into subset‐specific HCC.

Objectives To investigate the inter- and intra-reader agreement of immune Response Evaluation Criteria in Solid Tumors (iRECIST) and Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) in patients with lung cancer treated with immunotherapy. Materials and Methods This retrospective study included 85 patients with lung cancer treated with PD-1 blockade. Four radiologists evaluated computed topography (CT) scans before and after initiation of immunotherapy using iRECIST and RECIST 1.1. Weighted kappa (k) with equal weights was used to assess the intra-reader agreement between 2 repeated reads on overall response at all time points, best overall response, and the response at the time point of progression, as well as the intra-reader agreement between iRECIST and RECIST. The inter-reader agreement was calculated using Light’s kappa. Results Intra-reader agreement for overall response at all time points, best overall response, and time point of progression was substantial to almost perfect for both iRECIST and RECIST 1.1 (k = 0.651–0.983). Inter-reader agreement was substantial for iRECIST (κ = 0.657–0.742) while RECIST 1.1 was moderate to substantial (κ = 0.587–0.686). The level of inter-reader agreement was not higher on repeat read for iRECIST (κ = 0.677–0.709 and κ = 0.657–0.742 for first and second read, respectively) as well as for RECIST 1.1 (κ = 0.587–0.659 and κ = 0.633–0.686 for first and second read, respectively). Almost perfect agreement was observed between RECIST 1.1 and iRECIST at first (κ = 0.813–0.923) and second read (κ = 0.841–0.912). Conclusion The inter- and intra-reader agreement of iRECIST is high and similar to RECIST 1.1 in patients with lung cancer treated with immunotherapy.

Most pancreatic ductal adenocarcinomas (PDAC) are lethal and resistant to immunotherapy. Thus, identifying the immunogenic subgroup (iPDAC) and therapeutic targets can save lives. Herein, we present molecular features of iPDAC. 3 cohorts (A, B, C) from 288 patients whose sequenced tumors (MSK-IMPACT) were classified by homologous recombination deficiency groups. MSI-H were excluded. Survival, tumor mutation burden, genomic instability score, and enriched pathways for each cohort are included in Table 1. Patients in A (BRCA1/2/PALB2) had longer survivals vs B/C. 61 samples were selected for bulk RNAseq analysis for A vs C. Gene Ontology was enriched for upregulated humoral, T cell, and neutrophil immunity. CIBERSORT suggested higher infiltration of gamma delta T (Tgd) cells (p=0.039) and neutrophils (p=0.012), but lower Treg (p=0.001). Multidimensional insights in cellular components of cancer, immune, stroma, and neural genes were obtained by single nuclear RNA (snRNAseq) analysis from 30 biopsies for A vs C. 10x Genomics Chromium platform for library and Scanpy for computational analysis after Cell Ranger pipelines were used. 61,868 nuclei were profiled from 18 (13 baseline and 5 matched longitudinal) samples after quality evaluation. UMAP accurately clustered cells from each patient. Long-term survivors (LTS) had heterogenous baseline immune cell infiltrates of plasma cells, neutrophils, and CD8 (+) cytotoxic T cells. In matched samples of LTS, evolution of more prominent CD8 (+) T cells, macrophage, plasma cell, and neutrophil were observed. Single nucleus T-Cell Receptor sequencing for clonal trajectory inference will be done to determine the associated single cell molecular features contributing to iPDAC and identify novel targets for future intervention. Table 1. Cohort (Total: N=288) A: core HRD (BRCA1/2/PALB2) B: non-core HRD (ATM, BARD1, BLM, CHEK2, RAD50, RAD51C, RTEL1, MUTYH) C: others without HR-gene alterations Number (%) 48 (16.6) 19 (6.5) 221 (76) Median overall survival (95% confidence Interval) 33 months (3.6-64) 16 (11- not reached) 16 (14-18) Tumor Mutation Burden (TMB) 4.4 3.5 3.9 Genomic Instability Score (GIS, HRD score) 26 12 13 Gene Ongology term, enrichment score, adjusted p-value Adaptive immune response, GO:0002250, 0.49, 1.69e-10 Not included Reference to cohort A Humoral immune response, GO:0006959, 0.58, 1.67e-9 T cell activation, GO:0042110, 0.44, 2.75e-8 Neutrophil chemotaxis, GO:0030593, 0.73, 4.3e-10 Citation Format: Wungki Park, Catherine O'Connor, Shigeaki Umeda, Roshan Sharma, Yingjie Zhu, Elias-Ramzey Karnoub, Anna Varghese, Kevin C. Soares, Alejandro Jimemez, Asli Yavas, Kenneth H. Yu, Balachandran P. Vinod, Joanne F. Chou, Danny N. Khalil, Kelsen David, Hulya Sahin Ozkan, Olca Basturk, Marinela Capanu, Tal Nawy, Michael F. Berger, Ghassan K. Abou-Alfa, Jorge S. Reis-Filho, Ronan Chaligne, Nadeem Riaz, Dana Pe'er, Christine Iacobuzio-Donahue, Eileen M. O'Reilly. Molecular profiles and single cell analysis identify immunogenic pancreatic ductal adenocarcinoma (iPDAC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6421.

Purpose: Characterizing germline and somatic ATM variants (gATMm, sATMm) zygosity and their contribution to homologous recombination deficiency (HRD) is important for therapeutic strategy in pancreatic ductal adenocarcinoma (PDAC). Experimental Design: Clinico-genomic data for patients with PDAC and other cancers with ATM variants were abstracted. Genomic instability scores (GIS) were derived from ATM-mutant cancers and overall survival (OS) was evaluated. Results: Forty-six patients had PDAC and pathogenic ATM variants including 24 (52%) stage III/IV: gATMm (N = 24), and sATMm (N = 22). Twenty-seven (59%) had biallelic, 15 (33%) monoallelic, and 4 indeterminate (8%) variants. Median OS for advanced-stage cohort at diagnosis (N = 24) was 19.7 months [95% confidence interval (CI): 12.3–not reached (NR)], 27.1 months (95% CI: 22.7–NR) for gATMm (n = 11), and 12.3 months for sATMm (n = 13; 95% CI: 11.9–NR; P = 0.025). GIS was computed for 33 patients with PDAC and compared with other ATM-mutant cancers enriched for HRD. The median was lower (median, 11; range, 2–29) relative to breast (18, 3–55) or ovarian (25, 3–56) ATM-mutant cancers (P < 0.001 and P = 0.003, respectively). Interestingly, biallelic pathogenic ATM variants were mutually exclusive with TP53. Other canonical driver gene (KRAS, CDKN2A, SMAD4) variants were less frequent in ATM-mutant PDAC. Conclusions: ATM variants in PDAC represent a distinct biologic group and appear to have favorable OS. Nonetheless, pathogenic ATM variants do not confer an HRD signature in PDAC and ATM should be considered as a non-core HR gene in this disease.

Background It is unknown how body fat distribution modulates the cardiometabolic risk of testicular cancer survivors after cisplatin-based chemotherapy. Methods For 455 patients enrolled in the Platinum Study at Memorial Sloan Kettering Cancer Center, visceral (VAT) and subcutaneous (SAT) adipose tissue was quantified on prechemotherapy computed tomography. The VAT-to-SAT ratio was calculated as a quantitative measure of central adiposity. Endpoints were incidence of new posthemotherapy cardiometabolic disease (new antihypertensive, lipid-lowering, or diabetes medication), and postchemotherapy Framingham risk scores. Cox models and linear regression with interaction terms were applied. Postchemotherapy body fat distribution was analyzed in 108 patients. All statistical tests were 2-sided. Results The baseline median age was 31 years (interquartile range [IQR] = 26-39 years), body mass index (BMI) was 26 kg/m2 (IQR = 24-29 kg/m2), and the VAT-to-SAT ratio was 0.49 (IQR = 0.31-0.75). The median follow-up was 26 months (IQR = 16-59 months). Higher prechemotherapy VAT-to-SAT ratios inferred a higher likelihood of new cardiometabolic disease among patients with a BMI of 30 kg/m2 or greater (age-adjusted hazard ratio = 3.14, 95% confidence interval = 1.02 to 9.71, P = .047), but not other BMI groups. The prechemotherapy VAT-to-SAT ratio was associated with postchemotherapy Framingham risk scores in univariate regression analysis (exp(β)-estimate: 2.10, 95% confidence interval = 1.84 to 2.39, P Conclusions In testicular cancer survivors, central adiposity is associated with increased cardiometabolic risk after cisplatin-based chemotherapy, particularly in obese or young men. Weight gain after chemotherapy occurs preferentially in the visceral compartment, providing insight into the pathogenesis of cardiovascular disease in this population.

Pancreatic adenocarcinoma (PDAC) remains a refractory disease; however, modern cytotoxic chemotherapeutics can induce tumor regression and extend life. A blood-based, pharmacogenomic, chemosensitivity assay using gene expression profiling of circulating tumor and invasive cells (CTICs) to predict treatment response was previously developed. The combination regimen of 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX) and gemcitabine/nab-paclitaxel (G/nab-P) are established frontline approaches for treating advanced PDAC; however, there are no validated biomarkers for treatment selection. A similar unmet need exists for choosing second-line therapy.The chemosensitivity assay was evaluated in metastatic PDAC patients presenting for frontline treatment. A prospective study enrolled patients (n = 70) before receiving either FOLFIRINOX or G/nab-P at a 1:1 ratio. Six milliliters of peripheral blood was collected at baseline and at time of disease progression. CTICs were isolated, gene-expression profiling was performed, and the assay was used to predict effective and ineffective chemotherapeutic agents. Treating physicians were blinded to the assay prediction results.Patients receiving an effective regimen as predicted by the chemosensitivity assay experienced significantly longer median progression-free survival (mPFS; 7.8 months vs. 4.2 months; hazard ratio [HR], 0.35; p = .0002) and median overall survival (mOS; 21.0 months vs. 9.7 months; HR, 0.40; p = .005), compared with an ineffective regimen. Assay prediction for effective second-line therapy was explored. The entire study cohort experienced favorable outcomes compared with historical controls, 7.1-month mPFS and 12.3-month mOS.Chemosensitivity assay profiling is a promising tool for guiding therapy in advanced PDAC. Further prospective validation is under way (clinicaltrials.gov NCT03033927).

Background Patients with advanced hepatocellular carcinoma (HCC) who received second line sorafenib plus doxorubicin following disease progression on sorafenib were shown retrospectively to have improved progression free survival (PFS) and overall survival (OS). Sorafenib plus doxorubicin combination may synergistically promote ASK‐1 mediated apoptosis in cancer cells through RAF‐1 inhibition. Thus, we conducted this phase II study of sorafenib and doxorubicin combination following progression on sorafenib. Methods Patients with histologically confirmed advanced HCC, confirmed radiologic progression on sorafenib, Karnofsky performance status (KPS) ≥70%, and Child‐Pugh A liver cirrhosis were eligible. Patients received sorafenib 400 mg twice daily and doxorubicin 60 mg/m2 once every 3‐weeks. The primary endpoint was OS at 6 months (OS6). Secondary endpoints included safety, PFS, OS, response rate (RR) by RECIST 1.1. Additional endpoints included baseline and on‐treatment tumor ASK‐1 and pERK expression levels by immunohistochemistry (IHC) and the correlation with PFS, RR, and OS. Results Thirty patients were enrolled in the study, 86% were male, median age was 64 years. OS6 was 76.6% (95%CI: 57.2%‐88.1%). Median OS was 8.6 (95%CI: 7.3‐12) months, and median PFS reached 3.9 (95%CI: 2.4‐4.6) months. Three (11%) partial responses were observed and 17 patients (61%) had stable disease. Pertinent grade 3‐4 adverse events that occurred in more than 10% of patients included neutropenia (16%), febrile neutropenia (10%), anemia (10%), thrombocytopenia (10%), elevated AST (23%) and ALT (10%), hypophosphatemia (10%), and fatigue (10%). No association with the difference in baseline and post‐treatment ASK‐1 and pERK level of expression by IHC and survival outcomes was detected. Conclusion Sorafenib plus doxorubicin following progression on sorafenib did not show any improved outcome. We do not recommend further development or use of this combination in HCC., Sorafenib plus doxorubicin was evaluated as a second line therapy for advanced HCC. The association with the difference in baseline and post treatment ASK‐1 and pERK level of expression by IHC and survival outcomes was evaluated yet not detected. Sorafenib plus doxorubicin following progression on sorafenib did not show any improved outcome.

Background Fibrolamellar carcinoma (FLC) is a rare primary liver cancer of young adults. A functional chimeric transcript resulting from the in-frame fusion of the DNAJ homolog, subfamily B, member 1 (DNAJB1), and the catalytic subunit of protein kinase A (PRKACA) genes on chromosome 19 is believed to be unique in FLC, with a possible role in pathogenesis, yet with no established therapeutic value. The objective of the current study was to understand the molecular landscape of FLC and to identify potential novel therapeutic targets. Methods Archival fresh, formalin-fixed, paraffin-embedded samples from patients with FLC who prospectively consented to an institutional review board-approved protocol were analyzed using Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT), a next-generation sequencing assay encompassing up to 468 key cancer genes. Custom targeted RNA-Seq was performed in selected patients. Demographics, treatment, and outcome data were collected prospectively. Survival outcomes were estimated and correlated with mutation and/or copy number alterations. Results A total of 33 tumor samples from 31 patients with FLC were analyzed. The median age of the patients at the time of diagnosis was 18 years and approximately 53% were women. The DNAJB1-PRKACA fusion transcript was detected in 100% of patients. In 10 of 31 patients in which MSK-IMPACT did not detect the fusion, its presence was confirmed by targeted RNA-Seq. TERT promoter mutation was the second most common, and was detected in 7 patients. The median follow up was 30 months (range, 6-153 months). The 3-year overall survival rate was 84% (95% CI, 61%-93%). Conclusions The DNAJB1-PRKACA fusion transcript is nonspecific and nonsensitive to FLC. Its potential therapeutic value currently is under evaluation. Opportunities currently are under development for therapy that may be driven or related to the DNAJB1-PRKACA fusion transcript or any therapeutic target identified from next-generation sequencing in patients with FLC.

Lessons Learned Androgen receptor as assessed by immunohistochemistry is expressed in a high proportion of patients with hepatocellular carcinoma (HCC). Enzalutamide at 160 mg orally daily is safe and tolerable in patients with advanced HCC but has no single-agent antitumor activity. Enzalutamide, a CYP3A4 inducer, at a standard dose of 160 mg reduces the exposure of sorafenib, a CYP3A4 substrate. Enzalutamide and sorafenib is safe and tolerable in patients with advanced HCC, but the addition of enzalutamide to sorafenib did not enhance the antitumor activity of sorafenib. Background Androgen receptor (AR) interference is deleterious to hepatocellular carcinoma (HCC) in preclinical models. Methods This is a multicenter, phase Ib study of enzalutamide ± sorafenib in patients with advanced HCC. In part 1, a 3 + 3 dose de-escalation design with expansion established the recommended phase II dose (RP2D) of enzalutamide in patients in whom sorafenib treatment had failed. In part 2, a 3 + 3 dose escalation with expansion established the safety of enzalutamide with sorafenib in treatment-naive patients with HCC. Secondary objectives included objective response rate (ORR), progression-free survival (PFS), overall survival (OS), pharmacokinetics (PK), and determination of AR expression by immunohistochemistry. A 7-day run-in with sorafenib alone in part 2 allowed assessment of the impact of enzalutamide on sorafenib pharmacokinetics. Results In part 1, 16 patients received enzalutamide 160 mg daily. No dose-limiting toxicity (DLT) occurred; 1 patient required dose reduction. Responses were not observed; median PFS and OS were 1.8 (95% confidence interval [CI]: 1.6–3.6) and 7 (95% CI: 3.6 to not reached [NR]) months, respectively. In part 2, patients received sorafenib 400 mg daily (4) or twice a day (8) both with enzalutamide at the recommended phase II dose—no DLTs were observed. ORR was 10% (95% CI: 0.3–44.5), and median PFS and OS were 2.9 (95% CI: 1.6 to NR) and 6.7 (95% CI: 4.6 to NR) months, respectively. Enzalutamide reduced sorafenib exposure by 60%. Tumor AR expression did not associate with outcome. Conclusion Enzalutamide is ineffective in HCC; further development is not supported by this study.

685 Background: Adjuvant mFFX (5-fluorouracil, leucovorin, irinotecan, oxaliplatin) is a standard-of-care for fit patients (pts) with resected PDAC, owing to the immediate practice-changing PRODIGE 24/CCTG PA6 trial (2018). Five-year follow-up: median overall survival (mOS) 53.3 months (m) and median disease-free survival (mDFS) 21.4 m for mFFX vs 35.5 m and 12.8 m for gemcitabine (Conroy, JAMA Onc, 2022). RWO for pts outside a clinical trial are lacking. Herein, we report RWO for pts with resected PDAC and intent for adjuvant mFFX at Memorial Sloan Kettering (MSK). Methods: Institutional databases were queried to identify pts with resected PDAC who received any dose of adjuvant mFFX. Demographic, clinicopathologic, genomic, dosing details, and survival data were abstracted from medical and pharmacy records. Primary endpoint was to determine recurrence-free survival (RFS) calculated from start date mFFX to disease recurrence or death and OS calculated from start date mFFX to death. Secondary endpoints included dose reductions, significant treatment delay, toxicity profile, patterns of failure, genomic associations with outcome. RFS and OS are estimated using the Kaplan-Meier method. Study approved by MSK IRB. Results: N = 114 pts with resected PDAC treated with mFFX (> 1 dose) identified between 01/2015- 01/2022. Median age: 67 years (range 35 to 82); N = 43 (38%) > 70 years, N = 18 (16%) > 75 years, N = 2 (2%) > 80 years. Baseline Performance Status recorded in N = 104: N = 31 (30%) ECOG 0, N = 64 (62%) ECOG 1, N = 9 (9%) ECOG 2. Disease stage: N = 36 (32%) stage III, N = 61 (54%) stage II, and N = 17 (15%) pts stage I. Resection status: N = 91 (80%) R0, N = 23 (20%) R1. Presence of lymphovascular invasion: N = 92 (81%), perineural invasion N = 106 (93%). Median baseline CA 19-9: 20 U/mL (IQR; 9, 38). Median follow up: 22.4 m (range 6.2, 50.4). Median time from surgery to start mFFX: 7.4 weeks (IQR; 6.1, 9.3). Median # of mFFX doses received: 12 (IQR; 12, 12), N = 90 (79%) pts completed 12 doses. Dosing details available N = 112. N = 55 (49%) prescribed less than full dose of > one drug at baseline. Dose reductions: N = 57 (51%). N = 69 (62%) received < 12 doses oxaliplatin. N = 97 (87%) received growth factor support. mRFS: 31 m (95% CI; 23, Not Reached). N = 18 (16%) were hospitalized for treatment related adverse events, no therapy related mortality. N = 24 (21%) received adjuvant radiation therapy. One-year OS rate: 93% (95% CI; 89%, 98%) and 2-year OS rate: 78% (95%CI: 70%, 88%). Among patients with recurrence (N = 44), most common sites of first recurrence were: liver (N = 18, 41%), local (N = 14, 32%), and lung (N = 9, 20%). Conclusions: These data endorse mFFX as standard therapy for resected PDAC. The survival signals are encouraging in a prognostically unfavorable albeit select patient population (relative to PRODIGE 24). Dose adjustments to facilitate optimizing tolerability is key. Additional genomic and subtype analyses are underway.

653 Background: PanNENs represent 1-2% of all pancreatic neoplasms. The genomic landscape derived from PanNEN tumor tissue has been described previously. There are little data detailing the frequency of genetic alterations identified in cfDNA in an advanced PanNEN population, the plasma-tissue concordance of detected alterations, and the clinical utility of cfDNA. Methods: Patients (pts) with metastatic PanNENs underwent collection of cfDNA for NGS using the MSK-IMPACT 505 gene assay between March 2017 and April 2020. Matched tissue based NGS with the FDA authorized MSK-IMPACT gene assay was completed when tumor tissue was available. For some pts, plasma and tumor tissue were sequenced at multiple time points. Clinical actionability of sequence variants was annotated by OncoKB. Clinicopathologic characteristics were extracted, and data are herein reported. Results: 25 unique pts with metastatic PanNENs had 32 plasma samples analyzed. The majority had well differentiated (22/25; 88%), intermediate grade disease (13/25; 52%). 6 (24%) pts had well differentiated high grade disease and 3 (12%) had poorly differentiated neuroendocrine carcinomas. After extraction, median cfDNA yield per sample was 23.98ng (range: 3.2 to 500.1). Mutations were detected in 21(66%) of 32 samples (10 pre systemic therapy, 10 at progression, 12 post response to therapy or while stable on therapy). The most frequently mutated genes occurring in >10% of patients were DAXX (28%), TSC2 (24%), MEN1 (24%), ARID1B (20%), ARID1A (12%) and ATRX (12%). 23 (92%) pts underwent tumor tissue sequencing with MSK-IMPACT with a median time of 6.9 (range: 0.5-33.4) months between tissue collection and time of plasma analysis. NGS of cfDNA identified the most common mutations observed in tumor tissue for: DAXX (5/6; 83%), TSC2 (3/6; 50%), MEN1 (5/12; 42%), ARID1A (3/5; 60%) and ATRX (3/6; 50%). In 21/23 (91%) paired samples, additional mutations not seen in tissue were detected in plasma and included TSC2, TP53, EGFR, VHL, and BRCA2. Potentially actionable mutations were identified in sequenced cfDNA in 8/25 (32%) patients including 4 TSC2 mutations (level 3b), 1 ATM mutation (level 3b), 2 ARID1A mutations (level 4) and 1 KRAS mutation (level 4). One patient who was treated with larotrectinib for an ETV6:NTRK3 fusion detected on tumor sequencing ultimately developed resistance with a NRTK3 G623R alteration identified through sequencing of cfDNA at radiographic disease progression. Conclusions: NGS of cfDNA in metastatic PanNENs, across the spectrum of WHO-defined tumor grade/differentiation, revealed tumor-associated genetic alterations in 66% of plasma samples. Clonal evolution, actionable alterations, and resistance mechanisms can be detected through circulating cfDNA genotyping and may serve as a powerful tool to better understand disease biology of a disease that often changes over time and through therapy.

PURPOSE To determine if radiomic measures of tumor heterogeneity derived from baseline contrast-enhanced computed tomography (CE-CT) are associated with durable clinical benefit and time to off-treatment in patients with recurrent ovarian cancer (OC) enrolled in prospective immunotherapeutic trials. MATERIALS AND METHODS This retrospective study included 75 patients with recurrent OC who were enrolled in prospective immunotherapeutic trials (n = 74) or treated off-label (n = 1) and had baseline CE-CT scans. Disease burden (total tumor volume, number of disease sites), radiomic measures of intertumor heterogeneity (cluster-site entropy, cluster-site dissimilarity), and intratumor heterogeneity of the largest lesion (Haralick texture features) were computed. Associations of clinical, conventional imaging, and radiomic measures with durable clinical benefit and time to off-treatment were examined. RESULTS In univariable analysis, fewer disease sites, lower intertumor heterogeneity (lower cluster-site entropy, lower cluster-site dissimilarity), and lower intratumor heterogeneity of the largest lesion (higher energy) were significantly associated with durable clinical benefit ( P ≤ .031). More disease sites, presence of pleural disease and/or distant metastases, higher intertumor heterogeneity (higher cluster-site entropy, higher cluster-site dissimilarity), and higher intratumor heterogeneity of the largest lesion (higher Contrastlargest-lesion) were significantly associated with shorter time to off-treatment ( P ≤ .034). In multivariable analysis, higher Energylargest-lesion (indicator of lower intratumor heterogeneity; P = .006; odds ratio, 1.41) and fewer disease sites ( P = .003; odds ratio, 1.64) remained significant indicators of durable clinical benefit (multivariable model C-index, 0.821). Higher cluster-site dissimilarity (indicator of higher intertumor heterogeneity) was a modest but single independent indicator of shorter time to off-treatment ( P = .004; hazard ratio, 1.19; C-index, 0.6). CONCLUSION Fewer disease sites and lower intra- and intertumor heterogeneity modeled from the baseline CE-CT may indicate better response of OC to immunotherapy.

Purpose: Immune checkpoint inhibitors (ICI) are effective in only a minority of patients with esophagogastric cancer (EGC). Here, we aimed to identify predictors of durable clinical benefit to ICI in EGC. Experimental Design: Patients with advanced EGC treated with ICIs at Memorial Sloan Kettering Cancer Center (New York, NY) were identified. Clinicopathologic variables were assessed. In patients profiled by MSK-IMPACT–targeted sequencing, outcomes were correlated with tumor genomic features. Results: One-hundred sixty-one patients were treated with ICIs (110 with anti–PD-1/PD-L1 antibodies and 51 with anti–CTLA-4 and PD-1/PD-L1 antibodies). The median progression-free survival (PFS) and overall survival (OS) were 1.7 and 4.9 months, respectively. Greater number of disease sites (≥3), liver metastases, treatment with ≥3 prior therapies and ECOG performance status ≥2 were associated with poorer PFS and OS. Patients treated with combination ICI and those with PD-L1–positive tumors had improved outcomes. There was no difference in outcomes between patients treated with antibiotics during or in the 2 months preceding ICI treatment versus those who were not. Occurrence of irAEs was associated with improved OS. In genomically profiled tumors (n = 89), survival was associated with increasing tumor mutation burden (TMB). However, in multivariable analyses and when microsatellite unstable (MSI) patients were excluded, a significant association was no longer observed. Conclusions: In patients with advanced EGC, heavily pretreated patients, those with high-volume disease and/or poor PS were less likely to benefit from ICI. irAEs were associated with improved OS. TMB correlated with improved survival, but this association was not observed when MSI-high patients were excluded.

Irreversible T cell exhaustion limits the efficacy of programmed cell death 1 (PD-1) blockade. We observed that dual CD40-TLR4 stimulation within a single tumor restored PD-1 sensitivity and that this regimen triggered a systemic tumor-specific CD8(+) T cell response. This approach effectively treated established tumors in diverse syngeneic cancer models, and the systemic effect was dependent on the injected tumor, indicating that treated tumors were converted into necessary components of this therapy. Strikingly, this approach was associated with the absence of exhausted PD-1(hi) T cells in treated and distant tumors, while sparing the intervening draining lymph node and spleen. Furthermore, patients with transcription changes like those induced by this therapy experienced improved progression-free survival with anti–PD-1 treatment. Dual CD40-TLR4 activation within a single tumor is thus an approach for overcoming resistance to PD-1 blockade that is unique in its ability to cause the loss of exhausted T cells within tumors while sparing nonmalignant tissues.

Purpose: VEGFR2-directed therapy is commonly used to treat metastatic esophagogastric cancer, but disease progresses in most patients within months. Therapeutic resistance is likely mediated in part by co-occurring amplifications of the genes for multiple oncogenic receptor tyrosine kinases (RTK). We therefore tested the efficacy of combined inhibition of VEGFR1-3, PDGFα/β, and FGFR1-3 using nintedanib. Patients and Methods: Patients with metastatic esophagogastric adenocarcinoma and disease progression on first-line chemotherapy were treated with nintedanib 200 mg twice daily. The primary endpoint was progression-free survival (PFS) at 6 months; secondary endpoints included tumor response and safety. Tumor biopsies were profiled by targeted capture next-generation sequencing (NGS) to identify molecular predictors of drug response. Results: The study achieved its primary endpoint; 6 of 32 patients (19%) were progression-free at 6 months. With a median follow-up of 14.5 months among survivors, median overall survival (OS) was 14.2 months [95% confidence interval (CI), 10.8 months–NR]. Nintedanib was well tolerated; grade ≥ 3 toxicities were uncommon and included grade 3 hypertension (15%) and liver enzyme elevation (4%). FGFR2 alterations were identified in 18% of patients but were not predictive of clinical outcome on nintedanib therapy. Alterations in cell-cycle pathway genes were associated with worse median PFS (1.61 months for patients with cell-cycle pathway alterations vs. 2.66 months for patients without, P = 0.019). Conclusions: Nintedanib treatment resulted in modest disease stabilization in patients with metastatic esophagogastric cancer. Alterations in cell-cycle pathway genes and increased global copy-number alteration (CNA) burden warrant further study as prognostic or predictive biomarkers.

Purpose: Mutations in the RAS/RAF/MEK/ERK signaling pathway are commonly found in biliary tract cancer (BTC). Binimetinib, a selective inhibitor of MEK1/2, has single-agent activity. Preclinical data support binimetinib combination with chemotherapy, when given in an interrupted dosing schedule. Patients and Methods: A phase I/II trial evaluated binimetinib in combination with gemcitabine and cisplatin in patients with untreated advanced BTC. The primary endpoints were to determine the MTD (phase I), and PFS 6 and RR (phase II). Tumor tissue for targeted gene sequencing and blood samples for peripheral blood pERK expression were evaluated. Patients received oral binimetinib twice daily with gemcitabine and cisplatin on day 8 and 15 of a 21-day cycle. Binimetinib was held for 2 days prior to and on day of each chemotherapy treatment. Results: Twelve patients enrolled in the phase I showed the MTD of binimetinib at 45 mg orally twice daily with gemcitabine 800 and cisplatin 20 mg/m2. Twenty-nine patients were treated in the phase II. Six patients treated at MTD in phase I were evaluable as part of phase II. PFS 6 months was 54% and RR was 36%. Median overall survival was 13.3 months (95% CI, 9.8–16.5). MSK-IMPACT 410-gene panel showed aberrations in the RAS–RAF–MEK–ERK pathway and mutations in PIK3CA, AKT2, PIK3CG, BRAF, and MAP3K1 in responding patients. Conclusions: Binimetinib with gemcitabine and cisplatin did not show an improvement in PFS 6 and RR. Molecular profiling may help select patients who may benefit from this triplet therapy, which is not planned at this time.

4029 Background: Induction FOLFOX followed by PET-directed CRT prior to surgery demonstrated positive results in the CALGB 80803 study. We investigated the safety and efficacy of adding D, an anti-PD-L1 antibody, to PET-directed CRT. Methods: Patients (pts) with locally advanced esophageal/GEJ adenocarcinoma were enrolled. Pts received 2 cycles of mFOLFOX6 prior to repeat PET/CT. PET responders (≥35% reduction in SUV (PETr)) received 5-FU/capecitabine and oxaliplatin with RT to 50.4Gy, while induction PET non-responders (PETnr) received carboplatin/paclitaxel with RT. All Pts received D 1,500 mg q4W ×2 starting 2 weeks prior to CRT. Esophagectomy was planned 6-8 weeks after CRT. Pts with R0 resections received adjuvant D 1,500mg q4W ×6. The primary endpoint was the pathologic complete response (pCR) rate. Results: 36 pts were enrolled. Clinical ≥T3 disease was seen in 32 pts (88.9%, cT4 = 3) and ≥N1 in 23 (63.9%) pts. PD-L1 CPS was ≥1 in 25 (71.4%) of 35 tested with 14 (40%) ≥5. Microsatellite instability (MSI) was identified in 3 (8.3%) pts. 25 (70%) pts were PETr. Preop treatment was well tolerated with no new safety signals. Three pts had disease progression prior to surgery. pCR was identified in 8 (22.2%) pts and 22 (64.7%) had major pathologic response (MPR; ypTanyN0 + ≥90% response). Those with MSI tumors had ≥90% treatment response (1 pCR, 1: ypT1aN0 99% response, 1: ypT2N0, 90% response). 17 (73.9%) of 23 cN+ pts had ypN0 disease. MPR was associated with PD-L1 ≥1 (p = 0.03) and with a higher tumor mutational burden (TMB; p = 0.016) on MSK-IMPACT testing. Adjuvant D was commenced in 27 pts, with a median number of 6 cycles. Early discontinuation was due to risks of visits due to COVID19 (4, 15%), progressive disease (3, 11%), late surgical complications (2, 7%) and immune toxicity (1, 4%). With a median follow-up of 30 months, OS rates were 92% [95%CI: 83%-100%] and 85 % [95%CI: 74%-98%] at 12 and 24 months post induction. 12 and 24-month PFS rates were 81% [95%CI: 69%-95%] and 71% [95%CI: 58%-88%] respectively. In the 33 operated pts, 12 and 24-month disease free survival was 82% [95%CI: 70%-96%] and 78% [95%CI: 65%-94%], respectively. In addition to SUV on PET, total lesion glycolysis (TLG) was correlated with pathologic response. In cases with borderline change in SUV, TLG could predict response to treatment. One PETnr with 30.8% reduction in SUV had 88.1% reduction in TLG and pCR. Conversely, a PETr (-36.3%) who had an increase in TLG (39.3%) had only 40% treatment response on pathology. Conclusions: The addition of D to induction FOLFOX and PET-directed CRT prior to surgery is safe and appears effective with a high rate of pathologic response, as well as encouraging survival data. PD-L1 CPS≥1 and higher TMB may be associated with MPR. TLG is a novel PET variable that should be studied prospectively. Additional correlatives and comparison to a cohort treated with standard PET-directed CRT will be presented. Clinical trial information: NCT02962063.

4110 Background: HCC is often diagnosed based on high-quality cross-sectional imaging, and when a biopsy is pursued, acquisition of tissue may be of limited quantity and quality or complicated by underlying medical comorbidities. NGS of tumor derived circulating cfDNA represents an investigational tool for non-invasive molecular profiling, that has the potential to aid in diagnosis, prognosis, and in monitoring disease status. Although prior reports have evaluated such technologies, few studies have included tumor tissues to confirm histology and to explore plasma-tissue gene concordance. Methods: The primary objective of this retrospective cohort study was to define genomic alterations in circulating cfDNA and to explore plasma-tissue genotype concordance in HCC pts. HCC pts underwent collection of cfDNA for NGS using the MSK-ACCESS 129-gene assay between August 2019 and February 2021. Matched tissue-based NGS with the FDA authorized MSK-IMPACT gene assay was completed when tumor tissue was available. Clinical actionability of sequence variants was annotated by OncoKB, an FDA recognized knowledge base. Clinicopathologic characteristics were extracted, and all data were reported with descriptive statistics. Results: 51 unique patients with 53 plasma samples had an HCC histological diagnosis. Pts were male (39, 76%), median age 69 (42-87), viral hepatitis-related (24, 47%), and advanced stage (Stage III:9, 18%; Stage IV:38, 74.5%). Extrahepatic disease and macrovascular involvement were observed in 28 (55%) and 19 (38%) pts, respectively. 22 (43%) pts had AFP ≥400 ng/mL. 49 (92.5%) of 53 plasma samples had detectable genomic alterations. Median cfDNA yield after extraction was 39.43 ng (range: 7.93-287.68). The most frequently mutated genes occurring in > 10% of patients were TERT (57%), TP53 (47%), CTNNB1 (37%), ARID1A (18%) and TSC2 (14%). The most common oncogenic pathways that contained alterations were WNT-β-Catenin (45%) and PIK3-AKT-TOR (25%). 37 (73%) pts underwent tissue sequencing with MSK-IMPACT with a median time of 9.0 months to the time cfDNA testing. MSK-ACCESS identified mutations observed in tumor in most cases: TERT (20/22; 91%), TP53 (16/17; 94%), CTNNB1 (11/12; 92%), ARID1A (6/6; 100%) and TSC2 (6/7; 86%). In 18 (49%) of 37 paired samples, additional mutations in cfDNA not seen in tumor were detected and included KRAS, EGFR, and TP53 alterations. Potentially actionable mutations were identified through cfDNA in 37% of cases including TSC1/2 (18%), BRCA1/ 2 (8%) and PIK3CA (8%). Conclusions: Circulating cfDNA genotyping with MSK-ACCESS identifies previously reported HCC tumor genomic profiles and revealed tumor-associated mutations in 92.5% of plasma samples. Ongoing efforts will explore predictive and prognostic implications of NGS at different HCC stages as well as kinetics of treatment response.

Purpose:Immune checkpoint inhibition (ICI) alone is not active in mismatch repair–proficient (MMR-P) metastatic colorectal cancer (mCRC), nor does radiotherapy alone result in objective systemic benefit. However, combined radiotherapy plus ICI can induce systemic antitumor immunity in preclinical and clinical models.Patients and Methods:In this single-center, phase II study, patients with chemotherapy-refractory MMR-P mCRC received durvalumab 1,500 mg plus tremelimumab 75 mg every 4 weeks plus radiotherapy. The primary endpoint was objective response rate (ORR) in nonirradiated lesions. Treatment and efficacy were correlated with peripheral immune cell profiles.Results:We enrolled 24 patients, and report outcomes after a median follow-up of 21.8 (range: 15.9–26.3) months. The ORR was 8.3% (2 patients) [95% confidence interval (CI), 1.0–27.0]. The median progression-free survival was 1.8 (95% CI, 1.7–1.9) months, median overall survival was 11.4 (95% CI, 10.1–17.4) months. Twenty five percent of patients (n = 6) had treatment-related grade 3–4 adverse events. We observed increased circulating CD8+ T lymphocyte activation, differentiation, and proliferation in patients with objective response.Conclusions:This combination of radiotherapy plus ICI study did not meet the prespecified endpoint criteria to be considered worthwhile for further study. However, rare instances of systemic immune augmentation and regression in nonirradiated lesions were observed (an abscopal response). Combination durvalumab and tremelimumab plus radiotherapy is feasible in MMR-P mCRC with a manageable safety profile. Further studies of novel immunotherapy combinations, and identification of biomarkers predictive of abscopal response are warranted.

Background Herein, we investigate the relationship between pancreatic stem cell markers (PCSC markers), CD44, and epithelial-specific antigen (ESA), tumor stroma, and the impact on recurrence outcomes in pancreatic ductal adenocarcinoma (PDAC) patients. Methods PDAC patients who underwent surgical resection between 01/2012–06/2014 were identified. CD44 and ESA expression was assessed by immunohistochemistry. Stroma was classified as loose, moderate, and dense based on fibroblast content. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier method and compared between subgroups by log-rank test. The association between PCSC markers and stroma type was assessed by Fisher’s exact test. Results N = 93 PDAC patients were identified. The number of PDAC patients with dense, moderate density, and loose stroma was 11 (12%), 51 (54%), and 31 (33%) respectively. PDAC with CD44+/ESA− had highest rate of loose stroma (63%) followed by PDAC CD44+/ESA+ (50%), PDAC CD44−/ESA+ (35%), CD44−/ESA− (9%) (p = 0.0033). Conversely, lack of CD44 and ESA expression was associated with the highest rate of moderate and dense stroma (91% p = 0.0033). No local recurrence was observed in patients with dense stroma and 9 had distant recurrence. The highest rate of cumulative local recurrence was observed in patients with loose stroma. No statistically significant difference in RFS and OS was observed among subgroups (P = 0.089). Conclusions These data indicate PCSCs may have an important role in stroma differentiation in PDAC. Our results further suggest that tumor stroma may influence the recurrence pattern in PDAC patients.

Trial Information Click here to access other published clinical trials. Lessons Learned FLC is a complex cancer with many implicated oncogenic pathways. Single or dual targeting does not appear to alter the natural history of the cancer, and novel therapeutics are needed. Estrogen deprivation therapy with letrozole and leuprolide, alone or in combination with the mTOR inhibitor, everolimus, did not demonstrate clinical activity in advanced fibrolamellar carcinoma. The study drugs were well tolerated when administered as single agents or in combination in this patient population. This study demonstrates that, despite the rarity of FLC, multicenter therapeutic clinical trials are feasible and support the value of this consortium. Background Fibrolamellar carcinoma (FLC) is an uncommon malignancy in young people and is sometimes associated with pregnancy and oral contraceptive use. Immunohistochemical staining and genetic profiling of FLC tumor specimens have revealed aromatase overexpression. The overexpression of mTOR and S6 kinase has been noted in 25% of FLC. On the basis of interaction between estrogen and the PI3K/Akt/mTOR pathway, we hypothesized that suppression of estrogen and mTOR signaling could have antineoplastic activity in FLC. Methods Patients were randomized to arm A (everolimus), arm B (letrozole/leuprolide; estrogen deprivation therapy [EDT]), or arm C (everolimus/letrozole/leuprolide). Upon disease progression, patients in arm A or B could proceed to part 2 (everolimus/letrozole/leuprolide). The primary endpoint was progression-free survival (PFS) at 6 months (PFS6) assessed using a Simon's minimax two-stage design, hypothesizing an improvement in PFS6 from 40% to 64% with the study regimen. Results Twenty-eight patients were enrolled. An unplanned analysis was performed because of perceived concern for lack of efficacy. Stable disease was observed in 9 of 26 evaluable patients (35%). PFS6 was 0%. Median overall survival (OS) was 12.4 months (95% confidence interval [CI], 7.4–20.9) for the whole study cohort. Grade 3 adverse events in ≥10% of patients were nausea (11%), vomiting (11%), anemia (11%), elevated aspartate transaminase (AST; 32%), alanine transaminase (ALT; 36%), and alkaline phosphatase (14%). All 28 patients experienced an event for PFS outcome, and four deaths were due to disease progression. Conclusion Neither EDT nor mTOR inhibition improved outcomes in FLC. Other treatment strategies are needed.

Background Data on drug-induced liver injury (DILI) and acute liver failure (ALF) in modern phase 1 oncology trials are limited, specifically with respect to the incidence and resolution of DILI and the safety of drug rechallenge. Methods This study reviewed all patients who were recruited to phase 1 oncology trials between 2013 and 2017 at Memorial Sloan Kettering Cancer Center. Clinicopathologic data were extracted to characterize DILI, and attribution was assessed on the basis of data prospectively generated during the studies. Logistic regression models were used to explore factors related to DILI and DILI recurrence after drug rechallenge. Results Among 1670 cases recruited to 85 phase 1 trials, 81 (4.9%) developed DILI. The rate of DILI occurrence was similar for patients in immune-based trials and patients in targeted therapy trials (5.0% vs 4.9%), as was the median time to DILI (5.5 vs 6.5 weeks; P = .48). Two patients (0.12%) met the criteria of Hy's law, although none developed ALF. The DILI resolved in 96% of the patients. Pretreatment factors were not predictive for DILI development. Thirty-six of the 81 patients underwent a drug rechallenge, and 28% of these patients developed DILI recurrence. Peak alanine aminotransferase during the initial DILI was associated with DILI recurrence (odds ratio, 1.04; 95% confidence interval, 1.0-1.09; P = .035). Conclusions In modern phase 1 oncology trials, DILI is uncommon, may occur at any time, and often resolves with supportive measures. Rechallenging after DILI is feasible; however, the high rate of DILI recurrence suggests that clinicians should consider the severity of the DILI episode and treatment alternatives.

Background KRAS, TP53, CDKN2A, and SMAD4 are established driver genes in pancreatic ductal adenocarcinoma (PDAC). This study was aimed at determining whether the mutational status of driver genes and those involved in DNA repair pathways are associated with clinical outcomes for individuals who undergo resection. Methods Eligible individuals were those who underwent resection of PDAC and consented to targeted sequencing of their primary tumor via Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT). Genomic alterations were determined on the basis of MSK-IMPACT results from formalin-fixed, paraffin-embedded samples. Associations between genomic alterations and clinical outcomes were assessed. Results Targeted sequencing was performed on 283 primary tumors resected between 2004 and 2017. The median follow-up was 23 months among survivors. Alterations in KRAS and TP53 were associated with worse overall survival (OS) in comparison to wild type (median for KRAS, 38.8 months [95% CI, 33.0-45.5 months] vs 91.0 months [95% CI, 34.8 months to not available (NA)]; P = .043; median for TP53, 37.4 months [95% CI, 32.1-42.8 months] vs 65.0 months [95% CI, 33.0 months to NA]; P = .035). KRAS G12D mutations were associated with worse OS (median, 31.6 months [95% CI, 25.3-45.5 months] vs 39.2 months [95% CI, 37.4-75.2 months]; P = .012). TP53 truncating mutations (median, 39.6 months [95% CI, 32.4-75.2 months] vs 33.9 months [95% CI, 24.0-39.0 months]; P = .020) and those associated with loss of heterozygosity (median, 26.6 months [95% CI, 21.6-44.2 months] vs 39.2 months [95% CI, 34.5-49.1 months]; P = .048) had decreased OS. TP53 alterations were independently associated with OS in a multivariate analysis (hazard ratio, 1.54; 95% CI, 1.01-2.33; P = .042). Individuals with germline alterations in homologous recombination deficiency (HRD) genes had improved OS in comparison with those without them (median, not reached vs 37.0 months; 95% CI, 33.0-49.8 months; P = .035). Conclusions In patients with resected PDAC, genomic alterations in KRAS and TP53 are associated with worse outcomes, whereas alterations in HRD genes are associated with a favorable prognosis. Further studies are needed to better define these alterations as biomarkers in resected PDAC.

437 Background: TACE is a standard of care for liver limited HCC and impacts the immune microenvironment, potentially augmenting the effects of immune checkpoint inhibitors. Methods: This is a multicenter phase 1 study of NIVO and deb-TACE in unresectable HCC pts and Child Pugh A cirrhosis (NCT03143270). The primary objective is to assess safety. Secondary objectives include response rate by RECIST v1.1, progression-free and overall survival by Kaplan-Meier methodology, and blood/tumor immune correlates. A 3 + 3 design with expansion cohort sequentially evaluates 3 cohorts of differing schedules of NIVO relative to deb-TACE. Deb-TACE (75mg of doxorubicin) is administered on Day 0. NIVO is dosed at 240mg IV every 14 days for 1 year (Cohort 1: NIVO begins day +14 after deb-TACE; Cohort 2, interrupted NIVO dosing begins at Day -28 but is held on the Day 0 then restarted on Day +14; Cohort 3, continuous NIVO dosing begins on Day -28 without interruption). Results: As of September 2021, 19 pts were treated [median 67 years (range: 54-78), male (80%), ECOG PS 0 (47%), Child Pugh A (100%), 3 pts in each cohort 1 and 2, 13 pts in cohort 3]. No cases of treatment related liver failure or Grade 5 adverse events (AEs) were observed. 1 DLT of Grade 3 transaminitis was observed in cohort 3 and resolved without intervention and did not recur with drug rechallenge. Median ALT at baseline, day 28, day 56, and end of treatment (EOT) were 27, 43.5, 36.5, and 29 U/L. Median bilirubin at baseline, day 28, day 56, and EOT were 0.6, 0.6, 0.5, and 0.6 mg/dL. Mean ALBI score at baseline (N=19) and EOT (N=14) were -2.75 ± 0.48 vs. -2.55 ± 0.50. The most common treatment-related AEs of any grade were fatigue (53%), ALT/AST increase (42%), fever (37%), and pruritis (32%). The objective response rate by RECIST v 1.1 was 21% (Table). 5/19 pts remained on study with SD or better for ≥12 (range 12-43) months. Updated survival analysis will be presented at the meeting; correlatives at a separate venue. Conclusions: Nivolumab administered with deb-TACE is safe with antitumor activity. This study provides a needed benchmark for the safety of embolization along with anti-PD1 therapy in liver limited HCC. The clinical question of combining immunotherapy with embolization to improve outcome over embolization alone remains investigational and several, pivotal, phase 3 studies are ongoing. Clinical trial information: NCT03143270. [Table: see text]

506 Background: Immune checkpoint inhibitors (ICIs) have antitumor activity in some solid tumors, however a role for ICI’s in the treatment of neuroendocrine neoplasms (NENs) is uncertain. We analyzed response and outcomes of NENs, both well differentiated neuroendocrine tumors (WDNET) and poorly differentiated neuroendocrine carcinomas (PDNEC), treated with ICIs at Memorial Sloan Kettering Cancer Center during the past decade. Methods: Patients with NENs who received ICIs between 2010-2021 were identified. Demographics, pathology characteristics, treatment response and outcomes were recorded. Progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier methods. Analysis of next-generation sequencing (NGS) results from archival tumor tissue was performed. Results: 57 patients with NENs treated with ICIs were identified (WDNET-16; PDNEC-41). All patients had heavily-treated metastatic disease (median number of prior systemic treatments, WDNET-4, PDNEC-2). Median time from diagnosis to ICI treatment was 41.5 months in WDNET, 8 months in PDNEC. WDNET response: 1 (6%) partial response (PR), 4 (25%) stable disease (SD), 10 (63%) progressive disease (PD). PDNEC response: 6 (15%) PR (5 microsatellite stable, 1 unknown), 3 (7%) SD, 32 (78%) PD. Median duration of ICI treatment: 2 months (range 0-27) in WDNET, 1 month (range 0-16) in PDNEC; median duration of treatment for the 7 responders was 11 months (range 2-27). While receiving ICIs, 3 PDNEC responders developed PD in an escape lesion (2 brain, 1 nodal) after response in all other disease sites and successfully continued ICI treatment post-RT of escape lesion. Six-month PFS was 20% [95%CI: 7%-55%] and 9.8% [95%CI: 4%-25%], OS 60% [95%CI: 40%-91%] and 37% [95%CI: 25%-56%], respectively in WDNET and PDNEC. NGS results were available in archival tumor tissue of 35 patients (61%); most common alterations were TP53 (20/26, 77%) and RB1 (14/26, 54%) in PDNEC versus ATM, SMAD4, CREBBP, and IRS2 (all 1/9, 11%) in WDNET. Conclusions: We observed limited activity for ICI’s in NEN treatment, primarily restricted to a subset of PDNEC. PFS/OS findings were consistent with historical data, reflecting the pathogenesis of distinct NEN subtypes.

347 Background: Brain metastases (BrM) rarely occur in patients with metastatic gastroesophageal adenocarcinoma (GEA) and represent a unique therapeutic challenge. We describe the unique clinical, molecular, and genomic factors associated with mGEA cancer and BrM development in order to help guide future clinical management. Methods: Patients (pts) with GEA seen at Memorial Sloan Kettering Cancer Center (MSKCC) from 2008-2019 and who had consented for genomic tumor profiling with MSK-IMPACT, a capture-based next-generation sequencing platform that detects mutations, copy-number variations, and select fusions, were retrospectively identified. Clinical and pathologic characteristics were reviewed. BrM were identified via International Classification of Diseases (ICD) billing codes and electronic medical record problem lists, and then manually validated. Survival was calculated from the time of BrM diagnosis until date of death or last follow up and estimated using the Kaplan-Meier method. Results: Fifty pts with GEA metastatic to the brain were identified. Most pts were male (86%) and white (80%), with primary tumor of the esophagus/gastroesophageal junction (82%) and intestinal-type Lauren histology (90%). Twenty-three pts (46%) were HER2 positive (defined as IHC 2+/FISH+ or IHC 3+). Frequencies of PTEN (16%) and EGFR (22%) alterations in primary or metastatic sites were enriched in pts with BM compared to that seen across the MSKCC retrospective cohort and the GEA Cancer Genome Atlas (TCGA) cohort. The majority (68%) of pts had stage IV disease at initial diagnosis, and 4 pts were found to have BrM within 1 month (mo) of stage IV diagnosis, while 27 pts developed BrM during therapy. Median time to BrM diagnosis was 18.3 mos (IQR 11.5-28.9) and 15.1 mos from stage IV diagnosis (IQR 4.8-25.5). Median survival was 7.6 mos from BrM diagnosis and 15.6 (95% CI 10.0-NR, n = 19), 7.6 (95% CI 2.5-NR, n = 13), and 4.3 (95% CI 3.5-12.3, n = 18) mos for pts with 1, 2-3, or 4+ BrM, respectively. Conclusions: GEA pts with BrM had increased frequency of HER2 positivity, as well as PTEN and EGFR alterations, compared to GEA pts overall historically. Further correlation between BrM development, molecular characteristics, and survival in a larger cohort will be presented.

615 Background: The occurrence of cutaneous metastasis from pancreatic cancer (PC) is rare, and the exact incidence is unknown. The literature to date is primarily limited to isolated case reports. Herein, we evaluate the clinical, genomic, and other descriptors of patients with PC and cutaneous metastases. Methods: Institutional databases were queried using search terms “pancreas cancer” and “cutaneous mets”. Clinical history, demographics, PC cutaneous metastasis details, and survival outcomes were abstracted. Results were described using descriptive statistics, and overall survival (OS) from the diagnosis of cutaneous metastasis was estimated using Kaplan-Meier methods. Results: Of 140 on initial search, 40 patients met inclusion criteria of PC and cutaneous metastases and were analyzed. The median age (Q1-Q3, IQR) of pancreatic cancer diagnosis was 66.0 (59.3-72.3, 12.9) years. Most common histologic subtype was adenocarcinoma (n= 39, 98%), and one patient had a neuroendocrine malignancy. Most patients had stage IV disease at diagnosis (n=26, 65%). The most common location of the primary tumor was tail of the pancreas (n=17, 43%). Forty-eight percent (n= 19) had cutaneous metastasis at/within one month of cancer diagnosis. Most patients received chemotherapy (n=37, 93%), with 14 patients (35%) patients also receiving local therapy in the form of local excision or radiation. The most common cutaneous metastasis site was the abdomen (n=40, 66%), with umbilical lesions occurring in 58% (n=23) of abdominal lesions. The median interval (Q1-Q3, IQR) between diagnosis of pancreatic cancer and development of cutaneous metastasis was 1.4 (0-14.5, 14.5) months. The median OS (95% CI) from cutaneous metastasis diagnosis was 11 months (7.0, 20). Table details the observed differences between umbilical vs. non-umbilical metastases. Sixteen of 40 (40%) patients underwent somatic testing. The most frequently mutated genes were KRAS (n= 16, 100%), TP53 (n=7, 44%), CDKN2Ap14ARF (n=5, 31%), CDKN2Ap16INK4A (n=5, 31%), and CDKN2B (n=3, 19%). Germline testing was undertaken in 12 (30%) patients, and pathogenic variants were observed in 3: CHEK2 (n=1, 8%), BRCA1 (n=1, 8%), and ATM (n= 1, 8%). Summary of cutaneous metastasis characteristics. Conclusions: Cutaneous metastases from PC are rare and can be present at the time of diagnosis of stage IV disease, occurring most frequently in the umbilicus. Cutaneous metastases can be classified into umbilical and non-umbilical metastases, which may be due to a different biology.[Table: see text]

BACKGROUND: Trastuzumab with cisplatin and fluoropyrimidine is the standard treatment in metastatic HER2-positive gastric or gastroesophageal (GE) junction adenocarcinoma, however there is limited data on the efficacy of trastuzumab in combination with a three-drug regimen in this setting. We examined the efficacy and safety of modified docetaxel, cisplatin and 5 fluorouracil (mDCF) plus trastuzumab in a single-arm multicenter phase II trial. METHODS: Previously untreated patients with HER2-positive metastatic gastric or GE junction adenocarcinoma were treated with mDCF and trastuzumab every 2 weeks. The primary endpoint was 6-month progression free survival (PFS); secondary endpoints included objective response rate, overall survival (OS), and toxicity. RESULTS: We enrolled 26 patients with metastatic HER2-positive gastric or GE junction adenocarcinoma between February 2011 and June 2015. The median age of patients was 62 years; 96% had a Karnofsky performance status equal to or greater than 80%. With a median follow-up of 25.4 months, the 6-month PFS was 73% (95% CI, 51% - 86%). The objective response rate was 65%, the median PFS was 13 months (95% CI, 6.4 – 20.7) and the median OS was 24.9 months (95% CI, 14.4 – 42.5). Grade 3/4 toxicities included neutropenia (42%), fatigue (23%), and hypophosphatemia (15%). There were no episodes of febrile neutropenia. CONCLUSION: The combination of mDCF and trastuzumab is effective and safe in patients with metastatic HER2-positive gastric or GE junction adenocarcinoma and can be considered as an option for selected patients. This trial is registered at ClinicalTrials.gov, number .

Background A phase 1 trial was used to evaluate a combination of cisplatin, gemcitabine, and escalating doses of veliparib in patients with untreated advanced pancreatic ductal adenocarcinoma (PDAC) in 2 cohorts: a germline BRCA1/2-mutated (BRCA+) cohort and a wild-type BRCA (BRCA-) cohort. The aims were to determine the safety, dose-limiting toxicities (DLTs), maximum tolerated dose, and recommended phase 2 dose (RP2D) of veliparib combined with cisplatin and gemcitabine and to assess the antitumor efficacy (Response Evaluation Criteria in Solid Tumors, version 1.1) and overall survival. Methods Gemcitabine and cisplatin were dosed at 600 and 25 mg/m2 , respectively, over 30 minutes on days 3 and 10 of a 21-day cycle. Four dose levels of veliparib were evaluated: 20 (dose level 0), 40 (dose level 1), and 80 mg (dose level 2) given orally twice daily on days 1 to 12 and 80 mg given twice daily on days 1 to 21 (dose level 2A [DL2A]). Results Seventeen patients were enrolled: 9 BRCA+ patients, 7 BRCA- patients, and 1 patient with an unknown status. DLTs were reached at DL2A (80 mg twice daily on days 1 to 21). Two of the 5 patients in this cohort (40%) experienced grade 4 neutropenia and thrombocytopenia. Two grade 5 events occurred on protocol. The objective response rate in the BRCA+ cohort was 7 of 9 (77.8%). The median overall survival for BRCA+ patients was 23.3 months (95% confidence interval [CI], 3.8-30.2 months). The median overall survival for BRCA- patients was 11 months (95% CI, 1.5-12.1 months). Conclusions The RP2D of veliparib was 80 mg by mouth twice daily on days 1 to 12 in combination with cisplatin and gemcitabine; the DLT was myelosuppression. Substantial antitumor activity was seen in BRCA+ PDAC. A randomized phase 2 trial is currently evaluating cisplatin and gemcitabine with and without veliparib for BRCA+ PDAC (NCT01585805). Cancer 2018;124:1374-82. © 2018 American Cancer Society.

Treatment with the ALK inhibitor crizotinib has been associated with complex renal cyst formation in patients with non-small cell lung cancer (NSCLC). Using patients treated with crizotinib, we aimed to evaluate the incidence of renal cyst formation, to identify risk factors for cyst formation and to provide a radiological description of cyst characteristics. Patients with ALK-positive NSCLC treated with crizotinib were retrospectively identified from an institutional database. Computed tomography (CT) imaging performed prior to and during crizotinib treatment was retrospectively reviewed to assess the size and complexity of pre-existing cysts, new cysts, and enlarging cysts. Demographic data including age, sex, ethnicity, smoking history and length of treatment were also recorded. Data from 60 patients with NSCLC treated with crizotinib at our institution between 6/5/2009 and 7/1/2015 were collected. 57 had CT imaging before and during treatment. Mean length of imaging follow-up was 18 months. 9 (16%) patients had cysts which enlarged or developed de novo during treatment. 2 (4%) patients developed complex renal cysts (1 of these patients also developed complex hepatic cysts). Female gender (p=0.008) and the presence of renal cysts on baseline scans (p=0.044) were significantly associated with cyst formation or growth. Renal cyst formation or growth occurred in 16% of crizotinib-treated patients. Women and those with pre-existing cysts were at greatest risk. Although the potential causal relationship between crizotinib use and renal cyst formation has yet to be fully defined, it is important for radiologists and clinicians to be aware of this finding.

PURPOSE Adrenocortical carcinomas (ACC) are rare and aggressive malignancies with limited treatment options. This study was undertaken to evaluate the immunogenicity of ACC. PATIENTS AND METHODS Patients with advanced ACC were enrolled in a phase II study to evaluate the clinical activity of pembrolizumab 200 mg every 3 weeks, without restriction on prior therapy. The primary end point was objective response rate. Efficacy was correlated with tumor programmed death-ligand 1 expression, microsatellite-high and/or mismatch repair deficient (MSI-H/MMR-D) status, and somatic and germline genomic correlates. RESULTS We enrolled 39 patients with advanced ACC and herein report after a median follow-up of 17.8 months (range, 5.4 months to 34.7 months). The objective response rate to pembrolizumab was 23% (nine patients; 95% CI, 11% to 39%), and the disease control rate was 52% (16 patients; 95% CI, 33% to 69%). The median duration of response was not reached (lower 95% CI, 4.1 months). Two of six patients with MSI-H/MMR-D tumors responded. The other seven patients with objective responses had microsatellite stable tumors. The median progression-free survival was 2.1 months (95% CI, 2.0 months to 10.7 months), and the median overall survival was 24.9 months (95% CI, 4.2 months to not reached). Thirteen percent of patients (n = 5) had treatment-related grade 3 or 4 adverse events. Tumor programmed death-ligand 1 expression and MSI-H/MMR-D status were not associated with objective response. CONCLUSION MSI-H/MMR-D tumors, for which pembrolizumab is a standard therapy, are more common in ACC than has been recognized. In advanced ACC that is microsatellite stable, pembrolizumab provided clinically meaningful and durable antitumor activity with a manageable safety profile.

Background Angiogenesis is critical to gastroesophageal adenocarcinoma growth and metastasis. Regorafenib is a multikinase inhibitor targeting angiogenic and stromal receptor tyrosine kinases. We evaluated whether regorafenib augments the antitumor effect of first-line chemotherapy in metastatic esophagogastric cancer. Materials and methods Patients with previously untreated metastatic gastroesophageal adenocarcinoma received 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) every 14 days and regorafenib 160 mg daily on days 4 to 10 of each 14-day cycle. The primary endpoint was 6-month progression-free survival (PFS). To identify predictive biomarkers of outcome, we examined correlations between genomic characteristics of sequenced pretreatment tumors and PFS. Results Between August 2013 and November 2014, 36 patients with metastatic esophagogastric cancer were accrued to this single-center phase II study (NCT01913639). The most common grade 3-4 treatment-related adverse events were neutropenia (36%), leucopenia (11%) and hypertension (8%). The 6-month PFS was 53% (95% confidence interval [CI], 38%-71%), the objective response rate was 54% (95% CI, 37%-70%), and the disease control rate was 77% (95% CI, 67%-94%). Next-generation sequencing did not identify any genomic alterations significantly correlated with response, and there was no association between homologous recombination deficiency and PFS with platinum-based chemotherapy. Conclusion Regorafenib (one week on-one week off schedule) is well tolerated in combination with first-line FOLFOX but does not improve 6-month PFS relative to historical control. Implications for practice Prognosis for metastatic esophagogastric cancer remains poor despite modern systemic therapy regimens. This phase II trial indicates that the combination of regorafenib and FOLFOX is well tolerated but does not add to the efficacy of first-line chemotherapy in metastatic esophagogastric cancer. Notably, recently reported data suggest potential synergy between regorafenib and the PD-1 inhibitor nivolumab. As this study demonstrates that regorafenib plus FOLFOX is safe, and combined chemotherapy and immunotherapy show favorable toxicity profiles, future studies combining immunotherapy with regorafenib and chemotherapy may be feasible.

5019 Background: Preferential fat accumulation in the visceral compartment (i.e. central adiposity) increases cardiovascular risk in the general population independent of body mass index (BMI). We investigated how body fat distribution modulates the cardiometabolic risk of male germ cell tumor (GCT) survivors after cisplatin-based chemotherapy. Methods: For 456 patients in The Platinum Study enrolled at Memorial Sloan Kettering Cancer Center, visceral (VAT) and subcutaneous (SAT) adipose tissue compartments were quantified on pre-chemotherapy computed tomography (CT) scans (median time between CT and chemotherapy: 13 days, range: 0-56). The VAT/SAT ratio was calculated as a quantitative indicator of central adiposity. Endpoints were (I) post-chemotherapy cardiovascular risk as per the office-based Framingham risk calculator, and (II) incidence of post-chemotherapy cardiometabolic disease defined as need for new anti-hypertensive drugs, or lipid-lowering drugs, or medication used to treat diabetes. Changes in fat distribution after chemotherapy were analyzed in a subgroup with post-chemotherapy CTs (n = 108; median interval from chemotherapy start: 18 months, range: 7-185). Linear regression with interaction terms (endpoint 1, subgroup analysis) and Cox proportional hazard regression (endpoint 2) were applied. Results: For all 456 patients, median age at chemotherapy initiation was 31 years and median follow-up was 27 months (range: 7, 207). At baseline (pre-chemotherapy), the median BMI was 26.2 kg/m2, and 102 patients (22.4%) had a BMI of ≥30 kg/m2. The median VAT/SAT ratio at baseline CT was 0.49, and positively associated with higher post-chemotherapy Framingham risk scores after adjustment for age, BMI, and blood pressure measurements at chemotherapy start, as well as post-therapy follow-up time (adjusted β-estimate: 1.36, 95% CI: 1.15, 1.59, p < 0.001). A higher VAT/SAT ratio also inferred a higher likelihood of new onset cardiometabolic disease in patients with BMI ≥30 kg/m2 (age-adjusted HR: 3.11, 95%CI: 1.01, 9.62, p = 0.048), but not in those with BMI < 30 kg/m2. In the subgroup analysis, we observed a significant increase of BMI after chemotherapy (mean: +1.1 kg/m2, 95% CI: +0.58, +1.54; p < 0.001). Changes in BMI were positively associated with changes of the VAT/SAT ratio (β-estimate: 3.0, 95% CI: 2.23, 4.04; p < 0.001), meaning that weight gain occurred preferentially in the VAT compartment, while weight loss tended to be paralleled by an improved body fat distribution. Conclusions: In male GCT patients, central adiposity at baseline increases cardiometabolic risk after cisplatin-based chemotherapy, particularly for obese individuals. Quantification of an individual’s body fat distribution on pre-chemotherapy CT could potentially help to identify high risk individuals who may benefit from intensified risk-modulating interventions.

e16204 Background: The somatostatin analogs (SSAs) octreotide LAR and lanreotide are equally acceptable in the NCCN guidelines to treat WDNETs. Average Sales Price for 1 year of lanreotide at 120mg is $106,802 versus $53,471 for 1 year of octreotide LAR 20mg and $80,206 for 1 year of 30mg. Lanreotide is given by “deep subcutaneous injection” while octreotide LAR is given intramuscularly. We conducted a randomized, blinded trial evaluating patient (pt) experience, as measured by injection site pain, with octreotide LAR and lanreotide, during the treatment of advanced, nonfunctional, WDNETs. We also investigated drug preference and financial toxicity in this pt population. Methods: This randomized single-blinded pilot study enrolled 51 pts recommended to begin SSA therapy. Pts received injections q 4 weeks and received 6 injections on study; Arm 1: octreotide LAR for 3 injections then lanreotide for 3 injections; Arm 2: lanreotide for 3 injections then octreotide LAR for 3 injections. Pts were blinded as to which agent they received throughout the study. Self-reported injection site pain scores were obtained after each of the first 3 injections using a 0 to 10 scale (0: “I didn’t feel it”; 10: “worst pain ever”). Primary endpoint was comparison of mean pain scores over the first 3 injections of octreotide LAR (Arm 1) or lanreotide (Arm 2). Secondary endpoints, evaluated with descriptive statistics, included pt-reported preference of octreotide LAR versus lanreotide, and willingness to pay for the preferred therapy, both assessed after 6 months of therapy by questionnaire. Results: 51 pts were enrolled (Arm 1: N = 26, Arm 2: N = 25). All pts were evaluable for the study primary endpoint. All pts received lanreotide at a dose of 120mg monthly; among those pts (49) receiving octreotide LAR, 30 (61%) received 20mg, 18 (37%) received 30mg, 1 (2%) received 10mg. No significant difference was identified in mean pain scores over the first 3 SSA injections; Arm 1: mean 2.4, standard deviation 1.9 versus Arm 2: mean 1.9, standard deviation 1.5 (p = 0.5). 34/51 (67%) pts (15 pts in Arm 1; 19 pts in Arm 2) were evaluated for secondary endpoints and completed post-therapy questionnaires. 7 (47%) in Arm 1 and 8 (42%) in Arm 2 indicated no drug preference at the end of the 6 months. There was a trend towards preference for octreotide LAR versus lanreotide in both arms, with more pts indicating mild or strong preference for octreotide LAR. 7 (50%) and 10 (56%) of pts in Arms 1 and 2, respectively, were unwilling to pay more for their preferred SSA; the rest of the cohort was willing to experience increased financial toxicity to receive their preferred SSA. Conclusions: This randomized, blinded study evaluating pt comfort with SSAs found minimal pain with both agents and no significant differences in pain scores between octreotide LAR versus lanreotide. Clinical trial information: NCT03289741.

244 Background: Subgroup analysis of trials data suggested a favorable prognostic role for microsatellite instability high (MSI-high) status in resectable gastric cancer, but a lack of survival benefit from neoadjuvant/adjuvant chemotherapy; questioning current standard of care for MSI-high locally advanced gastric cancer. To help guide treatment decision making, we retrospectively studied the interaction between MSI status and chemotherapy on survival in a single institution. Methods: All clinically advanced (tumor stage 3-4 or positive lymph nodes) gastric cancer patients that underwent gastrectomy between 2000-2018 with MSI status available from immunohistochemistry (IHC, deficient mismatch repair protein expression (dMMR) vs proficient (pMMR)) or DNA next generation sequencing testing (NGS, MSI-high vs low/stable (MSS)) were included. Clinicopathological characteristics and overall survival (OS) was compared between patients with neoadjuvant/adjuvant chemotherapy and without, stratified for MSI status, by Kaplan-Meier and Cox regression analysis. Results: From a total of 1,844 clinically advanced patients with resection, MSI status was available in 559 as determined by IHC in 420, NGS in 88, and both in 51 with a concordance rate of 50/51 (98%). Tumors were dMMR/MSI-high in 84 (15%) and pMMR/MSS in 475 (85%). Patients with dMMR/MSI-high tumors were more often older, female, and had distal tumors with intestinal subtype. Neoadjuvant and/or adjuvant chemotherapy was administered in 53 (63%) in the dMMR/MSI-high group and 367 (77%) in the pMMR/MSS (p = 0.006). Median (interquartile range) time of follow-up was 32 (19-57) months. In the total cohort, OS after 3 years was 82% in the dMMR/MSI-high and 59% in pMMR/MSS (p < 0.001). In the patients with neoadjuvant/adjuvant chemotherapy only, the dMMR/MSI-high had improved OS (3-years OS: 80% vs 60%, p = 0.001), and after adjustment for age and clinical tumor stage in multivariable analysis, dMMR/MSI-high status was associated with improved OS (HR 0.38 95%CI 0.22-0.68). In the dMMR/MSI-high group only, 3-year OS was 80% with chemotherapy vs 86% without (p = 0.374), and chemotherapy was not associated with a difference in OS after multivariable analysis (HR 1.03 95%CI 0.40-2.66). In case of neoadjuvant chemotherapy, grade 1 pathological response ( > 90%) was observed in 1/41 (2.4%) of the dMMR/MSI-high tumors vs 43/278 (16%) of the pMMR/MSS tumors respectively (p = 0.026). Conclusions: The incidence of MSI-high tumors in our cohort of clinically locally advanced, resectable, gastric cancers was 15%. Patients with MSI-high tumors had worse pathological treatment response to neoadjuvant chemotherapy, but better OS, compared to microsatellite stable tumors. However, in patients with MSI-high tumors, OS was not altered by neoadjuvant/adjuvant chemotherapy. We recommend assessing MSI status in locally advanced gastric cancer.

BACKGROUND A positron emission tomography (PET) scan after induction chemotherapy before preoperative chemoradiation and surgery for esophageal adenocarcinoma predicts outcomes. Some patients with progression on PET after induction chemotherapy had long-term overall survival (OS) when they were changed to alternative chemotherapy during radiation. METHODS This study retrospectively reviewed esophageal adenocarcinoma patients who received induction chemotherapy and chemoradiation before planned surgery; all had undergone a PET scan before and after induction chemotherapy. RESULTS There were 201 patients, and 113 (56%) were PET responders (≥35% decrease in the maximum standardized uptake value of the tumor). All PET responders received the same chemotherapy during radiation, whereas 38 of the 88 PET nonresponders (43%) changed chemotherapy. Among the 152 patients who underwent surgery, the pathologic complete response rate was 15% for PET responders and 3% for PET nonresponders who did not change chemotherapy (P = .046). The median progression-free survival (PFS; 18.9 vs 10.0 months, P < 0.01) and OS (37 vs 25.3 months, P = .02) were significantly better for PET responders versus PET nonresponders who did not change chemotherapy. The median PFS for PET nonresponders who changed chemotherapy was 17.9 months, and it was superior to the median PFS for PET nonresponders who did not change chemotherapy (P = .01). For PET nonresponders, the 5-year OS rates were 37% for those who changed chemotherapy and 25% for those who did not change chemotherapy (P = .18). CONCLUSIONS A PET scan after induction chemotherapy predicts outcomes for locally advanced esophageal adenocarcinoma patients who undergo chemoradiation and surgery. The median PFS is improved, and trends toward improved OS appear possible in PET nonresponders who change chemotherapy during radiation. The fully accrued Cancer and Leukemia Group B 80803 study (NCT01333033) is evaluating this strategy. Cancer 2016. © 2016 American Cancer Society.

4559 Background: Pembrolizumab can be safely combined with trastuzumab and chemotherapy and has promising activity with median OS 27 months and 91% objective response rate in HER2-positive mEG cancer irrespective of PD-L1 status (NCT02954536; Janjigian ESMO 2019). Tumor biopsies and blood samples were collected in this phase II trial to identify molecular and immune predictors of response and resistance to PTC. Methods: Pre-treatment and post-progression biopsies were analyzed using WES and IHC (HER2, PD-L1). Peripheral blood was collected pre-treatment, every 9 weeks on-treatment and at progression for plasma ctDNA (Guardant 360, Guardant Health, Redwood, CA). Tumor-matched DNA alterations were identified by correlating ctDNA and solid tumor WES results. Landmark PFS analysis was used to compare ctDNA clearance status at 9 weeks post-treatment. Results: Baseline ctDNA was analysed from 31 of 37 patients of whom 84% (26/31) had tumor-matched ctDNA detected at baseline. Patients who cleared ctDNA at 9 weeks (n = 17/23) achieved a longer median PFS than those who did not - mPFS 12.3 months (95% CI 7.44-NA vs 3.9 months (95% CI 2.01-NA) (log-rank p = 0.02). On serial blood monitoring of 16 patients with eventual radiographic progression, ctDNA re-appearance preceded CT detection in 8 (50%) patients. WES was completed in 31 patients with pre-treatment, and 12 patients post-progression, including matched samples from 10 patients. Loss of HER2 over-expression/amplification was noted in 44% (7/16) of post-progression samples by IHC/FISH (2 IHC 0/1, 5 FISH-). In paired post-progression samples on WES, we observed loss of ERBB2 in 2 patients, and new amplifications of CCND1/3, FGF3/4/19, CDK6/12, KRAS, MYC, and MET, as well as mutations in KRAS, PIK3CD and PIK3RA. Plasma analysis at progression demonstrated copy number increases and/or new amplifications in MET, CKD6, PIK3CA, KRAS, FGFR2, EGFR and CCDN1 as well as KRAS, RB1, PTEN, NF1, NOTCH1, BRAF, and FGFR1 mutations. Conclusions: The majority of patients with previously untreated HER2 positive mEG have detectable plasma ctDNA at baseline. The re-appearance of ctDNA during therapy may serve as an early predictor of progression and help identify genetic drivers of acquired resistance. Loss of ERBB2 over-expression/amplification and activating MAPK alterations occur at PTC progression. Evaluation of tumor immune environment by multiplex IHC and additional ctDNA analysis is underway.

774 Background: For individuals ≤ 50 years old, cancer incidence is increasing, particularly gastrointestinal and obesity related cancers (Sung, Lancet Public Health 2019). Limited details are known about young onset PC. Herein, we report the epidemiologic, pathologic, and molecular characteristics of PC in patients (pts) ≤ 50 years. Methods: MSK institutional database was queried for medical and treatment history, genomics, and outcomes in pts ≤ 50 years old diagnosed with PC between January 2008 and July 2018. Neuroendocrine cancers were excluded. Overall survival (OS) from date of PC diagnosis was estimated using Kaplan-Meier methods. Results: N = 450 pts ≤ 50 years old with a diagnosis of PC were identified. Ninety-six percent had adenocarcinoma, and 4% had acinar cell carcinoma/other histologies. Table summarizes demographics. Median OS was 16 months in the entire cohort and 11.3 months in stage IV disease. For N = 236 pts diagnosed after 2014, 119 (50%) underwent successful somatic testing with at least one alteration identified, and 21/119 tumors were RAS wild-type with identification of several actionable alterations (NRG1 fusions (n=2), NTRK fusions (n=2), IDH1 R132C (n=1), and microsatellite unstable tumors (n=1) ). N = 114 pts had germline testing (routine after 2015), and 33/114 (29%) had pathologic germline alterations, including BRCA1/2 (n=18), CHEK2 (n=3), PALB2 (n=3), ATM (n=2), MLH1 (n=1), and MSH3 (n=1). Conclusions: Pathogenic germline alterations are present in a substantial percentage of pts with young onset PC, and actionable somatic alterations were seen frequently in the subgroup of young onset PC RAS-wild type tumors. These observations underpin the need for germline and somatic profiling in PC. [Table: see text]

525 Background: Regional therapies in HCC impact the immune microenvironment and may augment the effects of immune checkpoint inhibitors. Methods: This is a multicenter phase 1 study of NIVO and deb-TACE in unresectable HCC pts (BCLC Stage B) and Child Pugh A cirrhosis (NCT03143270). The primary objective is to assess safety. Secondary objectives include response rate by RECIST v1.1, progression-free and overall survival by Kaplan-Meier methodology, and blood/tumor immune correlates. A 3 + 3 design sequentially evaluates 3 cohorts of differing schedules of NIVO relative to deb-TACE. Deb-TACE (75mg of doxorubicin) is administered on Day 0. NIVO is dosed at 240mg IV every 14 days for 1 year (Cohort 1: NIVO begins day +14 after deb-TACE; Cohort 2, interrupted NIVO dosing begins at Day -28 but is held on the Day 0 then restarted on Day +14; Cohort 3, continuous NIVO dosing begins on Day -28 without interruption). Results: As of July 2019, 9 pts have been treated [median 65 years (range: 54-76), male (89%), viral (44%;1 HBV, 3 HCV), non-viral (56%;2 EtOH, 1 NASH, 2 unknown), prior resection (44%), prior regional therapy (44%), 3 pts in each cohort]. No cases of treatment related liver failure, dose-limiting toxicity, or Grade 5 adverse events (AEs) were observed. Grade ≥3 AEs possibly related to nivolumab, deb-TACE, or both included: transaminase elevation (1 pt: day 1 post TACE resolved in 7 days without treatment; 2 pts: ≥30 days post TACE resolved with steroids between 20-41 days), post-embolization syndrome (1 pt: resolved in 5 days), asymptomatic lipase increase (1 pt: resolved in 14 days), post-procedural groin hematoma (1 pt: resolved in 2 days). All 9 pts were evaluable for efficacy: 2 (22%) confirmed PR and 7 (78%) SD. 4/9 pts remain on study with SD or better—2 pts continue > 18 months post embolization with durable PRs. 12 months OS rate was 71%. Ongoing correlates will be presented at a separate meeting. Conclusions: Nivolumab given at various times relative to deb-TACE appears safe and tolerable. Cohort 3 continues to accrue to provide a better estimate of safety and antitumor activity of the combination. Clinical trial information: NCT03143270.

639 Background: gBRCA 1,2 mutations occur in 5-8% PDAC. Platinum and poly-ADP ribose polymerase inhibitors (PARPi) effective in BRCA-mut cancers. Phase I GC + V high RR 78%; combination may delay resistance in PDAC (O’Reilly, Cancer, 2018). Herein, we evaluate GC +/- V in a multi-national, randomized phase II trial. Methods: Eligibility: Untreated germline (g)BRCA, PALB2 mut PDAC; measurable stage III/IV; ECOG 0-1. Randomized 1:1 Arm A or B. Treatment: Arm A: G 600 mg/m2 IV, C 25 mg/m2 IV, d3 and 10, V 80 mg PO BID day 1-12, all q 3 weeks or Arm B: GC only. Primary endpoint: RECIST 1.1 response rate (RR). Simon 2-stage per arm: null hypothesis 10% vs promising 28%; type I, II error 10%. Secondary endpoints: progression-free survival (PFS), OS (m), disease control rate (CR+PR+SD), safety and correlative analyses. PFS, OS compared between arms using log-rank test and RR, DCR using Fisher’s exact test between arms. Results: N = 52 enrolled 01/14- 11/18. N = 2 withdrew Arm B. N = 50 for ITT. Male = 22 (44%), Female = 28. Median age = 64 years (range 37-82). BRCA1 N = 12, BRCA2 N = 35, PALB2 N = 3. Stage III N = 8; Stage IV N = 42. Hematologic Toxicity: Arm A vs Arm B: Gd 3-4 neutropenia 13 (48%) vs 7 (30%); Gd 3-4 platelets 15 (55%) vs 2 (9%); Gd 3-4 anemia 14 (52%) vs 8 (35%). Non-hematologic toxicity similar Arm A vs B. Exploratory analyses (combined Arms): Med OS if > 4 m platinum → PARPi: 23 m (95%CI 6.5- 53.9). Med OS by BRCA: BRCA1: 14 m (8.1- 18.5); BRCA2: 20.2 m (12.3- 24.4). Med OS by ECOG: ECOG 0: 23 m (13.8- 24.5); ECOG 1: 14.3 (8.1 vs 16.4). Two-year OS rate for entire cohort: 30.6% and 3-year OS: 17.8%. Conclusions: GC +/- V very active in gBRCA/PALB2 mut PDAC with high RR, PFS, OS with both A, B significantly exceeding threshold RR. Improved DCR arm A vs B, but with greater heme toxicity A vs B. Study confirms GC as reference treatment in gBRCA/PALB2 with durable survival in subset. Funding: National Cancer Institute, CTEP, Lustgarten Foundation, AbbVie. Clinical trial information: NCT01585805 . [Table: see text]

708 Background: Given encouraging responses of platinum agents and poly-ADP ribose polymerase inhibitors (PARPi) in BRCA mutated (mut) PDAC, we sought to identify patients (pts) with BRCA mut PDAC treated at MSKCC and to evaluate outcome. Methods: Institutional database at MSK with IRB approval was queried for PDAC germline (g) or somatic (s) BRCA1/2 mut. Genomic profiling, clinicopathologic characteristics and outcomes were collected. Overall survival (OS) from diagnosis was estimated using Kaplan-Meier method. Results: n = 126 with BRCA1/2 mut PDAC were identified between 1/2011-12/2018. n = 77 (61%) male and median age of 62 (range 24-85) at diagnosis. n = 78 (62%) had g BRCA mut (n = 21 BRCA1; n = 57 BRCA2). n = 54 (43%) had a family history of BRCA-related malignancies; 35pts (28%) with a personal history of other BRCA-associated malignancy. n = 66 (52%) AJCC stage IV; of these 43pts (65%) received platinum-based therapy with a partial response (PR) in 35pts (81%); median duration 7 months (m) (range 0.5-39m). n = 40 (32%) received ≥ 4 lines of therapy (range 1-6 lines). n = 44 (35%) received PARPi and 11% (n = 14) received immunotherapy. Median OS for the entire cohort 32.1 m (95% CI 23.9, 42.6). Median OS for stage I-II 49.9m (95% CI 38.5,-); stage III 43m (95% CI 33.9,-) and stage IV 19.1m (95% CI 19.1 16.1,25.8). We did not observe a statistically significant difference in OS between BRCA1 vs BRCA2 pts. Conclusions: BRCA mut PDAC constitutes a small but likely distinct biologic subgroup. Improved OS was notable relative to historical data, possibly due to the integration of platinum and PARPi therapy and possibly due to contribution from disease biology. [Table: see text]

Previous studies have shown that pharmacogenomic modeling of circulating tumor and invasive cells (CTICs) can predict response of pancreatic ductal adenocarcinoma (PDAC) to combination chemotherapy, predominantly 5-fluorouracil-based. We hypothesized that a similar approach could be developed to predict treatment response to standard frontline gemcitabine with nab-paclitaxel (G/nab-P) chemotherapy. Gene expression profiles for responsiveness to G/nab-P were determined in cell lines and a test set of patient samples. A prospective clinical trial was conducted, enrolling 37 patients with advanced PDAC who received G/nab-P. Peripheral blood was collected prior to treatment, after two months of treatment, and at progression. The CTICs were isolated based on a phenotype of collagen invasion. The RNA was isolated, cDNA synthesized, and qPCR gene expression analyzed. Patients were most closely matched to one of three chemotherapy response templates. Circulating tumor and invasive cells&rsquo, SMAD4 expression was measured serially. The CTICs were reliably isolated and profiled from peripheral blood prior to and during chemotherapy treatment. Individual patients could be matched to distinct response templates predicting differential responses to G/nab-P treatment. Progression free survival was significantly correlated to response prediction and &Delta, SMAD4 was significantly associated with disease progression. These findings support phenotypic profiling and &Delta, SMAD4 of CTICs as promising clinical tools for choosing effective therapy in advanced PDAC, and for anticipating disease progression.

The anti-HER2 antibody trastuzumab is standard care for advanced esophagogastric (EG) cancer with ERBB2 (HER2) amplification or overexpression, but intrinsic and acquired resistance are common. We conducted a phase II study of afatinib, an irreversible pan-HER kinase inhibitor, in trastuzumab-resistant EG cancer. We analyzed pretreatment tumor biopsies and, in select cases, performed comprehensive characterization of postmortem metastatic specimens following acquisition of drug resistance. Afatinib response was associated with coamplification of EGFR and ERBB2. Heterogeneous 89Zr-trastuzumab PET uptake was associated with genomic heterogeneity and mixed clinical response to afatinib. Resistance to afatinib was associated with selection for tumor cells lacking EGFR amplification or with acquisition of MET amplification, which could be detected in plasma cell-free DNA. The combination of afatinib and a MET inhibitor induced complete tumor regression in ERBB2 and MET coamplified patient-derived xenograft models established from a metastatic lesion progressing on afatinib. Collectively, differential intrapatient and interpatient expression of HER2, EGFR, and MET may determine clinical response to HER kinase inhibitors in ERBB2-amplified EG cancer. Significance: Analysis of patients with ERBB2-amplified, trastuzumab-resistant EG cancer who were treated with the HER kinase inhibitor afatinib revealed that sensitivity and resistance to therapy were associated with EGFR/ERBB2 coamplification and MET amplification, respectively. HER2-directed PET imaging and cell-free DNA sequencing could help guide strategies to overcome the emergence of resistant clones. See related commentary by Klempner and Catenacci, p. 166. This article is highlighted in the In This Issue feature, p. 151

Background Ampullary carcinoma (AC) is a rare gastrointestinal cancer. Pathogenic germline alterations (PGAs) in BRCA2 and potentially targetable somatic alterations (SAs) in ERBB2 and ELF3 have been previously described in AC. Memorial Sloan Kettering Cancer Center has implemented an opt-in strategy for germline testing (GT) and somatic testing (ST) for patients with AC to further evaluate the spectrum of PGAs and SAs. Methods Forty-five patients with pathologically confirmed AC prospectively consented with the Memorial Sloan Kettering Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) test (410-468 genes). A subset of the cohort (23 of the 45 patients) also consented to GT with MSK-IMPACT (76-88 genes). Germline data for 21 of the remaining 22 patients who had not consented to GT were obtained in a de-identified fashion without clinical correlation. Clinicopathologic features, treatment histories, and survival data for consenting patients were collected and analyzed. Results Pancreaticobiliary, intestinal, and mixed features of the 2 types were the primary pathologic subtypes of AC identified in this cohort. No difference in median overall survival was found between pathologic subtypes. Eight of 44 patients (18%) were identified as harboring pathogenic mutations in BRCA2, ATM, RAD50, and MUTYH. In addition, this study found a wide spectrum of SAs in genes such as KRAS, MDM2, ERBB2, ELF3, and PIK3CA. Two patients in the cohort underwent SA-targeted therapy, and 1 had a partial radiographic response. Conclusions Mutations in multiple somatic and germline genes were identified in this cohort. Significantly, actionable targets were identified in the tumors, and broader testing for PGAs and SAs should be considered for all patients with AC.

Background Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive cancers with high metastatic potential. Clinical observations suggest that there is disease heterogeneity among patients with different sites of distant metastases, yielding distinct clinical outcomes. Herein, we investigate the impact of clinical and pathological parameters on recurrence patterns and compare survival outcomes for patients with a first site of recurrence in the liver versus lung from PDAC following original curative surgical resection. Methods Using the Memorial Sloan Kettering Cancer Center ICD billing codes and tumor registry database over a 10 years period (January 2004–December 2014), we identified PDAC patients who underwent resection and subsequently presented with either liver or lung recurrence. Time from relapse to death (TRD) was calculated from date of recurrence to date of death. Using the Kaplan-Meier method, TRD was estimated and compared by recurrence site using log-rank test. Results The median overall follow-up was 37.3 months among survivors in the entire cohort. Median TRD in this cohort was 10.7 months (95%CI: 8.9–14.6 months). Patients with first site of lung recurrence had a more favorable outcome compared to patients who recurred with liver metastasis as the first site of recurrence (median TRD of 15 versus 9 months respectively, P = 0.02). Moderate to poorly or poor differentiation was associated more often with liver than lung recurrence (40% vs 21% respectively, P = 0.047). A trend to increased lymph node metastasis in the lung recurrence cohort was observed. Conclusion PDAC patients who recur with a first site of lung metastasis have an improved clinical outcome compared to patients with first site of liver recurrence. Our data suggests there may be epidemiologic and pathologic determinants related to patterns of recurrence in PDAC.

Purpose: Various genetic driver aberrations have been identified among distinct anatomic and clinical subtypes of intrahepatic and extrahepatic cholangiocarcinoma, and these molecular alterations may be prognostic biomarkers and/or predictive of drug response. Experimental Design: Tumor samples from patients with cholangiocarcinoma who consented prospectively were analyzed using the MSK-IMPACT platform, a targeted next-generation sequencing assay that analyzes all exons and selected introns of 410 cancer-associated genes. Fisher exact tests were performed to identify associations between clinical characteristics and genetic alterations. Results: A total of 195 patients were studied: 78% intrahepatic and 22% extrahepatic cholangiocarcinoma. The most commonly altered genes in intrahepatic cholangiocarcinoma were IDH1 (30%), ARID1A (23%), BAP1 (20%), TP53 (20%), and FGFR2 gene fusions (14%). A tendency toward mutual exclusivity was seen between multiple genes in intrahepatic cholangiocarcinoma including TP53:IDH1, IDH1:KRAS, TP53:BAP1, and IDH1:FGFR2. Alterations in CDKN2A/B and ERBB2 were associated with reduced survival and time to progression on chemotherapy in patients with locally advanced or metastatic disease. Genetic alterations with potential therapeutic implications were identified in 47% of patients, leading to biomarker-directed therapy or clinical trial enrollment in 16% of patients. Conclusions: Cholangiocarcinoma is a genetically diverse cancer. Alterations in CDKN2A/B and ERBB2 are associated with negative prognostic implications in patients with advanced disease. Somatic alterations with therapeutic implications were identified in almost half of patients. These prospective data provide a contemporary benchmark for guiding the development of targeted therapies in molecularly profiled cholangiocarcinoma, and support to the use of molecular profiling to guide therapy selection in patients with advanced biliary cancers. Clin Cancer Res; 24(17); 4154–61. ©2018 AACR.

Purpose The Women’s Environmental Cancer and Radiation Epidemiology (WECARE) study demonstrated the importance of breast cancer family history on contralateral breast cancer (CBC) risk, even for noncarriers of deleterious BRCA1/2 mutations. With the completion of WECARE II, updated risk estimates are reported. Additional analyses that exclude women negative for deleterious mutations in ATM, CHEK2*1100delC, and PALB2 were performed. Patients and Methods The WECARE Study is a population-based case-control study that compared 1,521 CBC cases with 2,212 individually matched unilateral breast cancer (UBC) controls. Participants were younger than age 55 years when diagnosed with a first invasive breast cancer between 1985 and 2008. Women were interviewed about breast cancer risk factors, including family history. A subset of women was screened for deleterious mutations in BRCA1/2, ATM, CHEK2*1100delC, and PALB2. Rate ratios (RRs) were estimated using multivariable conditional logistic regression. Cumulative absolute risks (ARs) were estimated by combining RRs from the WECARE Study and population-based SEER*Stat cancer incidence data. Results Women with any first-degree relative with breast cancer had a 10-year AR of 8.1% for CBC (95% CI, 6.7% to 9.8%). Risks also were increased if the relative was diagnosed at an age younger than 40 years (10-year AR, 13.5%; 95% CI, 8.8% to 20.8%) or with CBC (10-year AR, 14.1%; 95% CI, 9.5% to 20.7%). These risks are comparable with those seen in BRCA1/2 deleterious mutation carriers (10-year AR, 18.4%; 95% CI, 16.0% to 21.3%). In the subset of women who tested negative for deleterious mutations in BRCA1/2, ATM, CHEK2*1100delC, and PALB2, estimates were unchanged. Adjustment for known breast cancer single-nucleotide polymorphisms did not affect estimates. Conclusion Breast cancer family history confers a high CBC risk, even after excluding women with deleterious mutations. Clinicians are urged to use detailed family histories to guide treatment and future screening decisions for young women with breast cancer.