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PROOF 302 is an ongoing randomized, double-blind, placebo-controlled, adjuvant phase III trial (NCT04197986) in approximately 218 patients from 120 centers worldwide. Eligibility criteria include post-surgical high-risk muscle-invasive upper tract urothelial cancer (85% of patients) or urothelial bladder cancer (15%), susceptible FGFR3 alterations (activating mutations, gene fusions or rearrangements), ≤120 days following radical surgery and ineligible for/or refusing cisplatin-based (neo)adjuvant chemotherapy. Patients receive either oral infigratinib 125 mg or placebo daily on days 1–21 of a 28-day cycle for up to 52 weeks or until recurrence, unacceptable toxicity or death. Primary end point: centrally determined disease-free survival (DFS); secondary end points: investigator-assessed DFS, metastasis-free survival, overall survival and safety/tolerability; exploratory end points: correlative biomarker analysis, quality-of-life and infigratinib pharmacokinetics.

Per-patient ADA responses

Purpose: Seviteronel (INO-464) is a selective cytochrome P450c17a (CYP17) 17,20-lyase (lyase) and androgen receptor (AR) inhibitor with antitumor activity in vitro and in vivo. This open-label phase I clinical study evaluated the safety, tolerability, pharmacokinetics and activity of once-daily seviteronel in male chemotherapy-naïve subjects with castration-resistant prostate cancer (CRPC).Patients and Methods: Seviteronel was administered at 600 mg once daily with dose titration (DT) and in modified 3 + 3 dose escalation once-daily cohorts at 600, 750, and 900 mg without DT. The primary objectives of this study were to establish safety, tolerability, and the MTD of seviteronel in chemotherapy-naïve subjects with or without prior treatment with FDA-approved CRPC treatments, abiraterone acetate (AA), and enzalutamide. Secondary objectives were to assess pharmacokinetics, PSA, tumor response, and endocrine results.Results: Twenty-one subjects were enrolled. No dose-limiting toxicities (DLT) were observed through 750 mg once daily. Most treatment-emergent adverse events (AE) reported at grade 1–2. The most commonly reported AEs were fatigue (71%), dizziness (52%), blurred vision (38%), and dysgeusia (33%), with most AEs improving after dose reduction or dose interruption.Conclusions: Once-daily seviteronel was generally well tolerated in this phase I study of men with CRPC, a majority of which had progressed on prior AA or enzalutamide, or both. Of the doses evaluated, 600 mg once daily was chosen as the recommended phase II dose for future studies in subjects with CRPC. Clin Cancer Res; 24(21); 5225–32. ©2018 AACR.

Summary of mean (%CV) PK parameters of Total ADC and Active ADC after a single IV infusion of MEDI3726

CTC while on treatment (patients with at least one CTC measurement >50)

Mutation profiles in ctDNA: truncating and/or pathogenic mutations in DDR or DDR-related pathway

Supplemental Table 1. Reasons for docetaxel discontinuation Supplemental Figure 1. Safety and PK assessment schedule

Supplemental Table 1: Overview of Treatment Duration, Discontinuations and Dose Modifications Supplemental Figure 1: Seviteronel Plasma Concentrations over Time - Single Dose.

Purpose: Preclinical evidence suggests that both docetaxel and enzalutamide target androgen receptor translocation and signaling. This phase Ib study assessed the safety, tolerability, and pharmacokinetics of docetaxel when administered with enzalutamide as first-line systemic chemotherapy in men with metastatic castration-resistant prostate cancer (mCRPC).Experimental Methods: Docetaxel-naïve patients received 21-day cycles of docetaxel (75 mg/m2). Enzalutamide (160 mg/day) was administered daily starting on day 2 of cycle 1. Patients were allowed to stop and restart docetaxel at any time following cycle 2. Treatment continued indefinitely until unacceptable toxicity or discontinuation due to investigator or patient preference.Results: A total of 22 patients received docetaxel, of whom 21 also received enzalutamide. Docetaxel was administered for a median of 5.0 cycles and enzalutamide for a median of 12.0 months. With concomitant treatment, geometric mean docetaxel exposure decreased by 11.8%, whereas peak concentrations decreased by 3.7% relative to docetaxel alone. The most common toxicities observed during the period of concomitant therapy were neutropenia (86.4%) and fatigue (77.3%). Common toxicities observed with post-docetaxel enzalutamide were constipation (23.8%), decreased appetite (19.0%), fatigue (19.0%), and musculoskeletal pain (19.0%). Treatment with enzalutamide and docetaxel resulted in prostate-specific antigen decreases in almost all patients based on exploratory analysis of available baseline and on-study prostate-specific antigen data.Conclusions: The combination of docetaxel and enzalutamide is feasible, although higher rates of neutropenia and neutropenic fever than anticipated were observed. Reductions in docetaxel exposure with enzalutamide coadministration were not considered clinically meaningful. This combination warrants further study in a larger mCRPC population. Clin Cancer Res; 22(15); 3774–81. ©2016 AACR.

Purpose:MEDI3726 is an antibody–drug conjugate targeting the prostate-specific membrane antigen and carrying a pyrrolobenzodiazepine warhead. This phase I study evaluated MEDI3726 monotherapy in patients with metastatic castration-resistant prostate cancer after disease progression on abiraterone and/or enzalutamide and taxane-based chemotherapy.Patients and Methods:MEDI3726 was administered at 0.015–0.3 mg/kg intravenously every 3 weeks until disease progression/unacceptable toxicity. The primary objective was to assess safety, dose-limiting toxicities (DLT), and MTD/maximum administered dose (MAD). Secondary objectives included assessment of antitumor activity, pharmacokinetics, and immunogenicity. The main efficacy endpoint was composite response, defined as confirmed response by RECIST v1.1, and/or PSA decrease of ≥50% after ≥12 weeks, and/or decrease from ≥5 to Results:Between February 1, 2017 and November 13, 2019, 33 patients received MEDI3726. By the data cutoff (January 17, 2020), treatment-related adverse events (TRAE) occurred in 30 patients (90.9%), primarily skin toxicities and effusions. Grade 3/4 TRAEs occurred in 15 patients (45.5%). Eleven patients (33.3%) discontinued because of TRAEs. There were no treatment-related deaths. One patient receiving 0.3 mg/kg had a DLT of grade 3 thrombocytopenia. The MTD was not identified; the MAD was 0.3 mg/kg. The composite response rate was 4/33 (12.1%). MEDI3726 had nonlinear pharmacokinetics with a short half-life (0.3–1.8 days). The prevalence of antidrug antibodies was 3/32 (9.4%), and the incidence was 13/32 (40.6%).Conclusions:Following dose escalation, no MTD was identified. Clinical responses occurred at higher doses, but were not durable as patients had to discontinue treatment due to TRAEs.

PROOF 302 is an ongoing randomized, double-blind, placebo-controlled, adjuvant phase III trial (NCT04197986) in approximately 218 patients from 120 centers worldwide. Eligibility criteria include post-surgical high-risk muscle-invasive upper tract urothelial cancer (85% of patients) or urothelial bladder cancer (15%), susceptibleCancers of the bladder and other parts in the urinary system, especially those that are invasive and grow into the muscle layer, may need extra treatment after surgical removal of the tumor, particularly if there is a high risk of the cancer coming back. Chemotherapy regimens that include cisplatin are often used postoperatively, although some patients are unable to tolerate this treatment or refuse it. FGFR3, a protein that is encoded by the

Background Erdafitinib, a pan-fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor, was shown to be clinically active and tolerable in patients with advanced urothelial carcinoma and prespecified FGFR alterations in the primary analysis of the BLC2001 study at median 11 months of follow-up. We aimed to assess the long-term efficacy and safety of the selected regimen of erdafitinib determined in the initial part of the study. Methods The open-label, non-comparator, phase 2, BLC2001 study was done at 126 medical centres in 14 countries across Asia, Europe, and North America. Eligible patients were aged 18 years or older with locally advanced and unresectable or metastatic urothelial carcinoma, at least one prespecified FGFR alteration, an Eastern Cooperative Oncology Group performance status of 0–2, and progressive disease after receiving at least one systemic chemotherapy or within 12 months of neoadjuvant or adjuvant chemotherapy or were ineligible for cisplatin. The selected regimen determined in the initial part of the study was continuous once daily 8 mg/day oral erdafitinib in 28-day cycles, with provision for pharmacodynamically guided uptitration to 9 mg/day (8 mg/day UpT). The primary endpoint was investigator-assessed confirmed objective response rate according to Response Evaluation Criteria In Solid Tumors version 1.1. Efficacy and safety were analysed in all treated patients who received at least one dose of erdafitinib. This is the final analysis of this study. This study is registered with ClinicalTrials.gov, NCT02365597. Findings Between May 25, 2015, and Aug 9, 2018, 2328 patients were screened, of whom 212 were enrolled and 101 were treated with the selected erdafitinib 8 mg/day UpT regimen. The data cutoff date for this analysis was Aug 9, 2019. Median efficacy follow-up was 24·0 months (IQR 22·7–26·6). The investigator-assessed objective response rate for patients treated with the selected erdafitinib regimen was 40 (40%; 95% CI 30–49) of 101 patients. The safety profile remained similar to that in the primary analysis, with no new safety signals reported with longer follow-up. Grade 3–4 treatment-emergent adverse events of any causality occurred in 72 (71%) of 101 patients. The most common grade 3–4 treatment-emergent adverse events of any cause were stomatitis (in 14 [14%] of 101 patients) and hyponatraemia (in 11 [11%]). There were no treatment-related deaths. Interpretation With longer follow-up, treatment with the selected regimen of erdafitinib showed consistent activity and a manageable safety profile in patients with locally advanced or metastatic urothelial carcinoma and prespecified FGFR alterations.

11057 Background: Historically, Diversity, Equity, and Inclusion (DEI) efforts have largely been left out of private practice medical facilities – mainly present in large academic hospital centers. Virginia Oncology Associates (VOA), a member of The US Oncology Network, is an independent community oncology and hematology practice specializing in the diagnosis and treatment of cancer and blood disorders. VOA has approximately 600 total employees consisting of physicians and clinical and non-clinical staff. In August of 2020, VOA launched an initiative to foster a culture of inclusion with the creation of its Inclusion Council (IC). Sixteen employees’, both clinical (3 physicians) and non-clinical, were chosen to participate. The council reports to VOA’s joint policy board. Methods: The council partnered with an outside organization, Virginia’s Center for Inclusive Communities, to launch a practice-wide DEI training program focusing on unconscious bias and microaggression. The training was initially planned to be in person, but due to the constraints of the COVID pandemic, the training was performed using a virtual platform. The members of IC attended three two-hour sessions while other staff members and physicians were mandated to participate in at least one training session. After completion of the sessions, a survey was sent to all employees and physicians to measure the impact of DEI training. All employees were also given the opportunity to provide additional, anonymous, written feedback. Results: Table. A total of 169 employees responded. 72% of respondents agreed or strongly agreed that the program increased awareness of unconscious bias and microaggression, 67% felt that the program helps foster a culture of inclusion in the workplace, and 66% of respondents felt that the program met expectations. Conclusions: DEI efforts are vital in all aspects of health care delivery and oncology settings. DEI training met staff expectations and positively fostered a culture of inclusion by bringing attention to unconscious bias and microaggression in a community oncology practice.[Table: see text]

TPS600 Background: Radical surgery ± cisplatin‐based (neo)adjuvant therapy (NAT) is the mainstay of treatment for invasive urothelial carcinoma of the upper urinary tract (UTUC) or bladder (UBC), but recurrence rates are high. Furthermore, many patients (pts) are unable to receive NAT because of cisplatin ineligibility. Fibroblast growth factor receptor 3 (FGFR3) genetic alterations occur in up to 70% of UTUC and up to 20% of UBC, and may constitute a potential candidate for targeted therapy. Infigratinib (BGJ398), a selective FGFR1–3 inhibitor, has shown promising clinical activity and tolerability in pts with advanced urothelial carcinoma having FGFR3 alterations [Pal et al. Cancer Discov 2018]. PROOF 302 has been designed to investigate the efficacy and safety of infigratinib versus placebo as adjuvant therapy in pts with high-risk invasive urothelial carcinoma and FGFR3 alterations. Methods: PROOF 302 is a randomized, double-blind, placebo-controlled, phase III study of approx. 218 pts. Adults with high-risk invasive UTUC or UBC with FGFR3 genetic alterations (i.e. mutations, gene fusions or translocations) who are ≤120 days following surgical resection and ineligible for cisplatin-based adjuvant chemotherapy or with residual disease after cisplatin- based NAT are eligible. Those who received non cisplatin-based NAT are eligible if they have residual disease and are ineligible for adjuvant cisplatin. Pts receive oral infigratinib 125 mg or placebo (1:1 ratio) once daily on days 1–21 every 28 days for up to 52 weeks or until disease recurrence, unacceptable toxicity or death. Primary endpoint: centrally reviewed disease-free survival (DFS). Secondary endpoints: DFS including intraluminal low-risk recurrence; metastasis-free survival; overall survival; DFS (per investigator); safety and tolerability. Exploratory endpoints include: quality of life; pharmacokinetics; cell-free DNA (cfDNA) and/or RNA for resistance mechanisms. The study will involve approximately 120 centers worldwide. Enrollment is expected to begin in January 2020. Trial registration: EudraCT 2019-003248-63. Clinical trial information: EudraCT 2019-003248-63.

TPS335 Background: EZH2 is frequently mutated and/or overexpressed in numerous cancers. High EZH2 expression is correlated with poor outcomes in prostate cancer patients (Varambally, 2002). EZH2 inhibition combines synergistically with anti-androgen therapies in preclinical models of advanced prostate cancer, suggesting epigenetic reprogramming as a pathophysiologic mechanism to enhance the combination therapy (Ku, 2017; Xiao 2018; Constellation, unpublished). CPI-1205 is a potent, selective, and cofactor-competitive inhibitor of wild type and mutant EZH2 catalytic activity, which demonstrates anti-proliferative effects in prostate and other cancer cell models. Methods: We present a Phase 1b/2 multicenter study of CPI-1205 combined with either E or A/P in patients with mCRPC, which includes phase 1 dose escalation, an expansion cohort in heavily pretreated patients (HPEC), and a randomized phase 2 study. Key eligibility criteria include progressive mCRPC in patients previously treated with a second-generation androgen inhibitor, ECOG 0-1, and measurable or non-measurable disease. During the phase 1b, patients will receive CPI-1205 continuously in 28-day cycles combined with the standard dose of either E (160mg PO once daily) or A/P (1000mg PO once daily/5 mg BID). The primary objective in Phase 1b is to determine the safety, tolerability, and recommended phase 2 dose (RP2D) of CPI-1205 combined with either E or A/P. Secondary objectives include safety, pharmacokinetic and pharmacodynamic profiles, and anti-tumor activity. The HPEC arm, with Simon’s 2-stage design, may begin with the regimen that is deemed safe by the study safety committee. The primary endpoint of the HPEC arm is objective response rate (ORR) per PCWG3, with a requirement ≥ 1 measurable lymph node at baseline. Once RP2D is established, we will start a randomized Phase 2 trial of E or A/P combined with CPI-1205 vs. E or A/P alone. The co-primary endpoint includes PSA50 and composite response rate (either CTC 30% reduction or ORR per PCWG3). Patient accrual in US sites began in December 2017. Clinical trial information: NCT03480646.

Preclinical urothelial carcinoma models suggest activity of dasatinib, an oral SRC-family kinase (SFK) inhibitor. We sought to determine the feasibility and biologic activity of neoadjuvant dasatinib (Neo-D) in patients with muscle-invasive urothelial carcinoma of the bladder (miUCB) preceding radical cystectomy (RC).A prospective multisite phase II trial was conducted. Key eligibility criteria included: resectable miUCB (T2-T4a, N0, M0), and Eastern Cooperative Oncology Group performance status 0 to 1. Patients received oral Neo-D 100mg once daily for 28±7 days followed by RC 8 to 24 hours after the last dose. The primary end point was feasibility, defined as≥60% of patients with miUCB completing therapy without treatment-related dose-limiting toxicity (DLT). Pre- and posttreatment tumor immunohistochemistry of phosphorylated SFK (pSFK), Ki-67, and cleaved caspase (Cas)-3 results were analyzed by paired t test.The study completed full accrual with enrollment of 25 patients of whom 23 were evaluable for feasibility. The study achieved its primary end point with 15 patients (65%) completing therapy without treatment-related DLTs. DLTs included: fatigue (n = 2), pulmonary embolism, abdominal pain, supraventricular tachycardia, enteric fistula, hematuria, and dyspnea (n = 1 each). At RC, 5 patients (23%) hadpT2 disease. Analysis of pre- and posttreatment tumors demonstrated significantly decreased pSFK (P = 0.003) but no overall significant changes in Ki-67 or Cas3. In total, 4 cases demonstrated a nonsignificant decrease in Ki-67, of which 3 cases also demonstrated a decrease in pSFK and 2 cases had marginal increase in Cas3.Neo-D in miUCB patients was feasible and safe. Overall, significant inhibition of pSFK was observed without overall reduction of cellular proliferation or increase of apoptosis, although biologic anti-tumor activity may exist in a small subset of patients. These results highlight the potential utility of the neoadjuvant trial paradigm and suggest that clinical benefit of single-agent SFK inhibition in unselected patients with miUCB is unlikely.

Key members (a.k.a. "champions") within specific work units were provided with a brief training session designed to increase awareness of the benefits associated with influenza vaccination. The champions were responsible for encouraging members of their work units to accept an influenza vaccination and in some cases had the requisite training to administer the vaccination on site. Work units were randomly assigned to either champion present or champion absent conditions. Results show increased vaccination compliance for groups where a champion was present (N = 23). An independent sample t-test revealed a significant difference between the two groups t = 2.30, p.03 which resulted in a percentage change from 41% in the unchampioned group to 52% in the championed group. Analyses which included only those units that had a fully trained champion (N = 13) produced a similar percentage increase in vaccine uptake from 41% to 54% (although this did not reach statistical significance; p = .08). Overall, the presence of a unit champion did produce a clinically relevant increase in vaccination rates in championed work units. This result has implications for future vaccination campaigns in hospital settings. Future research targeting the barriers and drivers of influenza vaccination among HCWs is recommended.

Meeting abstracts Metastatic bladder cancer (MBC) is a relatively chemosensitive neoplasm yet response durations are generally short-lived. Recently, immune checkpoint blockade has demonstrated unparalleled activity in heavily pre-treated patients (pts) with MBC. The role of standard chemotherapy

To the investigator and clinician, prostate-specific antigen (PSA) level is a seemingly perfect outcome measure because it is easily assessable, quantitative, reproducible, and inexpensive. Whether post-therapy decline in PSA reflects true clinical benefit, and whether post-therapy declines can be used as an intermediate endpoint for accelerated drug approval is still open to question. At present, no drug has been approved strictly on the basis of a post-treatment decline in PSA, as it is unproven that such PSA changes are surrogates for true clinical benefits. Post-therapy PSA changes have been associated with improved survival in patients with castrate metastatic disease. The role of PSA changes as potential surrogates of clinical benefit have only been explored to a limited degree because to date, only two prospective randomized trials showing a survival benefit have been reported. Such trials are necessary, but not a sufficient pre-requisite to explore the potential role of any outcome measure as an intermediate endpoint. The clear demonstration that a post-therapy PSA change can account for all of the treatment effects seen is not yet available. A cytotoxic drug that does not produce any PSA decline is unlikely to be effective, but the converse is not always true because not all PSA rises represent a treatment failure. It is important to recognize that there are a range of clinical benefits to patients that can improve the quality and possibly the duration of survival, independent of PSA.

79 Background: Following docetaxel (D), treatment options for mCRPC include cabazitaxel (CBZ), abiraterone acetate (AA), and enzalutamide. With the introduction of new agents, optimal sequencing is undefined. We evaluated the prevalence of sequencing of AA and CBZ following D in a large community-based cohort to develop a hypothesis for the most optimal sequence. Methods: A retrospective analysis of treatment patterns using the MSH iKnowMed EHR was conducted. Post-D mCRPC patients receiving CBZ and/or AA at full EHR sites with ≥2 visits were included; clinical trial patients excluded. CBZ utilization between Jun’10 and May’12 and sequencing of CBZ or/and AA from Apr’11 and May’12 (when both drugs were available) were examined. OS, time to treatment failure (TTF), and demographics analyses are ongoing. Results: 667 evaluable patients were identified. Overall CBZ (n=359 pts/2 y) utilization declined between Jun’10-May’11 (n=232) and Jun’11-May’12 (n=127). From Apr’11 to May’12: overall AA (n=465 pts/y) utilization increased between Mar-May’11 (n=73) to Jun-Aug’11 (n=164) and subsequently decreased (n=57) from Mar-May’12. Between Apr’11-May’12, 130 patients received both CBZ and AA. More men (P

5018 Background: The abundant expression of prostate specific membrane antigen (PSMA) on prostate cancer cells provides a rationale for antibody therapy. PSMA ADC is a fully human antibody to PSMA linked to the microtubule disrupting agent monomethyl auristatin E (MMAE). It binds PSMA and is internalized within the cancer cell where cleavage by lysosomal enzymes release free MMAE, causing cell cycle arrest and apoptosis. A phase 1 dose escalation study of PSMA ADC in taxane-refractory mCRPC has been completed. Methods: Patients with progressive mCRPC following taxane-containing chemotherapy and ECOG status of 0 or 1 were eligible. PSMA ADC was administered by IV infusion Q3W for up to 4 cycles. Safety, pharmacokinetics, PSA, circulating tumor cells (CTC), immunogenicity and clinical progression were assessed. Serum PSMA ADC and total anti-PSMA ADC antibodies were measured by ELISA, and free MMAE was measured by LC/MS/MS.The dosing cohorts ranged from 0.4 mg/kg to 2.8 mg/kg. Subjects who benefitted from PSMA ADC were eligible for treatment in an extension study. Results: 52 subjects were dosed in 9 dose levels. All subjects received prior docetaxel, 6 also received cabazitaxel and 3 subjects also received paclitaxel. PSMA ADC was generally well tolerated with the most commonly seen adverse events being anorexia and fatigue. 16 patients reported peripheral neuropathies, including 3 with grade 3. Dose limiting toxicities (DLT) seen at 2.8 mg/kg were neutropenia (one death) and reversible elevations in liver function tests (LFTs). Antitumor activity was manifested as reductions either in PSA or in CTCs in approximately 50% of patients at ≥ 1.8 mg/kg PSMA ADC. Exposure to PSMA ADC increased with dose and was ~1,000-fold greater than MMAE exposure. There was no accumulation. Conclusion: PSMA ADC in this study was generally well tolerated in subjects with progressive mCRPC, previously treated with taxane. Antitumor activity was seen at doses ≥ 1.8 mg/kg. DLTs were neutropenia and reversible LFT abnormalities. The maximum tolerated dose was determined to be 2.5 mg/kg. A phase 2 trial of PSMA ADC in taxane refractory mCRPC has been initiated at 2.5 mg/kg. Clinical trial information: NCT01414283.

e15040 Background: A previously reported phase II trial demonstrated that the addition of C, a chimeric monoclonal antibody that binds EGFR to MP for mCRPC following docetaxel did not extend overal...

4555 Background: Cetuximab (C), a chimeric monoclonal antibody with binding affinity to the epidermal growth factor receptor (EGFR), is active against androgen-independent prostate cell (AIPC) lines. No established therapy prolongs survival in CRPC patients (pts) who have received prior docetaxel (D). Mitoxantrone (M) is often used in this setting. In other cancers, C can restore sensitivity to chemotherapy. The combination of C+M was tested in D-treated CRPC pts. Methods: Pts with metastatic CRPC with evidence of progression (PSA or imaging) after D were eligible. PCWG2 guidelines for nonmeasurable disease applied. Treatment: Arm 1 (CM) C 250 mg/m2 (except 400 mg/m2 on Day 1 Cycle 1) Days 1, 8, & 15 and M 12 mg/m2 Day1; Arm 2 (M) 12 mg/m2 Day1; all pts took oral prednisone (P) 10 mg daily. Cycles were 21-days. Arm 2 pts could crossover to Arm 1 if progression was documented prior to Cycle 7 and were analyzed as Arm 2b. Radiological assessments of disease and PSA were done every 4 cycles. Results: 115 pts...