Morris, Michael J.

5079 Background: Neoadjuvant CHT followed by RP did not increase 3-year biochemical progression free-survival (bPFS) compared to RP alone in men with CLHRPC. However, there is evidence that bPFS and overall survival over time was improved. In the current analysis we assessed whether CHT followed by RP improved pathological specimen features compared to RP alone. Methods: CALGB 90203 (Alliance) is a Phase III study which randomly assigned, in a 1:1 fashion, men with CLHRPC [biopsy Gleason Grade Group (GGG) 4 or 5 or Kattan pre-op nomogram bPFS < 60%] to RP alone or RP plus neoadjuvant CHT [androgen deprivation plus docetaxel (75 mg/m2 every 3 weeks for 6 cycles)]. We conducted an exploratory analysis comparing histologic findings, determined at the treating center, in the RP specimens of men receiving CHT plus RP and men treated with RP alone. We used the Chi-square test, with P-values adjusted by the Holm method for multiple comparisons. Results: A total of 788 men (median age, 62; range: 32-83 years) were randomized, with 738 ultimately undergoing RP. There was no difference in pathologic GGG (Table). Men treated with neoadjuvant CHT had a lower pathologic T-stage and lower likelihood of having seminal vesicle invasion (SVI), positive pelvic lymph nodes, or positive surgical margins (SM) (Table). Conclusions: Most pathologic features in the RP specimen were improved in men receiving neoadjuvant CHT compared to RP alone. The relationship between pathologic changes and the development of metastasis and survival require further analysis. RP pathologic outcomes. Summary statistics are calculated for the number of patients with non-missing data for each characteristic. Clinical trial information: NCT00430183. [Table: see text]

5038 Background: Platinum-based chemotherapy has shown palliative and radiographic benefit in small unselected studies of metastatic castration-resistant prostate cancer (mCRPC). Alterations in DNA damage repair genes (DDRmut), which occur in ~25% of patients with mCRPC, may sensitize to platinum-based chemotherapy, and may aid in the selection of patients for this therapy. We sought to evaluate the efficacy of platinum-based chemotherapy in DDRmut mCRPC. Methods: We performed a retrospective review of patients with prostate cancer who underwent tumor genomic profiling and received platinum-based chemotherapy. Deleterious alterations in a panel including BRCA2, BRCA1, ATM, FANCA, CDK12 or PALB2 were classified as DDRmut. Absence of deleterious alterations in those genes was classified as DDRwt. MSI-H cases were excluded from analysis. Electronic charts, PSA values, and scans were reviewed to assess for outcomes. Results: From October 2013 to July 2018, 109 patients with mCRPC received platinum-based chemotherapy. 64/109 had prior taxane progression and were PARP inhibitor (PARPi) naïve at the time of platinum-based chemotherapy. DDRmut was found in 16/64 (25%) of patients ( BRCA2, n = 6; ATM, n = 2; CDK12, n = 4; FANCA, n = 4; PALB2, n = 1). Visceral metastasis occurred in 4/16 (25%) of DDRmut patients and in 22/48 (46%) of DDRwt patients. PSA50 responses were more common among DDRmut (8/15 evaluable = 53%, 95% CI, 30-75%) than among DDRwt patients (5/42 evaluable = 12%, 95% CI, 5-25%). Time on platinum-based chemotherapy tended to be longer in the DDRmut group (median 3.1 vs 1.8 months; HR 0.73, 95% CI 0.42-1.26). Of 8 DDRmut patients ( BRCA2, n = 6; BRCA1, n = 1; ATM, n = 2) who received platinum-based chemotherapy after progression on a PARPi, 3/7 evaluable patients (43%) had RECIST response or stable disease, and 2/7 evaluable patients (29%) had a PSA50 response. Of 4 patients with ATM deleterious mutations, none had a radiographic or PSA50 response to platinum-based chemotherapy. Conclusions: Platinum-based chemotherapy showed activity in DDRmut mCRPC patients before and after PARPi treatment.

5008 Background: Androgen receptor (AR) signaling is an important growth mechanism in mCRPC, providing the rationale for treatment with AR axis inhibitors such as ENZ and AAP. Targeting AR with anti-androgens such as ENZ can result in compensatory autocrine and paracrine androgenic stimulation. Therefore, using ENZ with the androgen biosynthesis inhibitor AAP to dampen these resistance mechanisms could improve clinical outcomes relative to ENZ alone. Methods: Men with progressive mCRPC by Prostate Cancer Working Group 2 criteria were eligible. Prior treatment with taxanes for mCRPC and any prior treatment with ENZ or AAP was exclusionary. Patients (pts) were randomized 1:1 to ENZ or ENZ/AAP at standard FDA-approved doses. Randomization was stratified by prior chemotherapy and Halabi prognostic three risk groups. Castrating therapy was maintained. The primary endpoint was overall survival (OS) defined as the date of randomization from date of death or last follow-up. The log-rank test had 90% power to detect a hazard ratio for OS of 0.77 with a one-sided type I error rate of 0.025. Secondary endpoints included radiographic progression free survival (rPFS) and on-treatment PSA declines. Exploratory endpoints included imaging changes, and changes in serum biomarkers such as androgens, angiokines, and circulating microRNA and RNA. The primary analysis was based on the stratified log-rank test adjusting on the stratification factors. Results: Between January 2014 and August 2016, 1311 men were randomized: 657 to ENZ and 654 to ENZ/AAP. Groups were well balanced between arms, including stratification variables. 15.6% of pts were high risk, 35.3% intermediate, and 48.1% low. Median OS was 33.6 mo (95% CI 30.5-36.4) and 32.7 mo (29.9-35.4) respectively, two-sided p = 0.53. Fifty percent PSA decline rate was 80% vs. 76.5%. Grade 3-5 adverse events (AE) (all attributions) were 55.6% and 68.8% respectively. Treatment discontinuation due to AEs occurred in 5% and 12%, pt withdrawal in 5% and 13%, and progression or death in 57% and 48% of pts respectively. Conclusions: Addition of abiraterone acetate to enzalutamide did not prolong survival in men with mCRPC. The combination resulted in more AEs than enzalutamide alone. Support: U10CA180821, U10CA180882, U24CA196171; https://acknowledgments.alliancefound.org . Clinical trial information: NCT01949337.

TPS4596 Background: First-line treatment of mRCC has rapidly changed to include IPI-NIVO or CABO, with clinical benefit of each based on the Checkmate 214 and CABOSUN trials. Combination immunotherapy with VEGF therapies have shown benefit in the JAVELIN 101 and KEYNOTE 426 trials over sunitinib. It is yet unclear which patients (pts) benefit most from combination immunotherapy-VEGF inhibitors, and the optimal sequence of drugs. Methods: In an adaptive, randomized, multicenter, phase 3 trial (Alliance A031704, PDIGREE), pts will start treatment with induction IPI 1mg/kg and NIVO 3mg/kg intravenously (IV) once every 3 weeks. Key inclusion criteria include clear cell mRCC, IMDC intermediate or poor risk, Karnofsky performance status >70, and no prior treatments for mRCC. Based on 3-month radiographic assessment (after completing IPI-NIVO combination), pts with complete responses (CR) will undergo maintenance NIVO 480mg IV every 4 weeks, pts with progression of disease (PD) will switch to CABO 60mg oral daily, and pts with non-CR/non-PD will be randomized to NIVO 480mg IV every 4 weeks versus NIVO 480mg IV every 4 weeks with CABO 40mg oral daily. Randomization will be stratified by IMDC risk criteria and presence of bone metastases. The primary endpoint of the study is overall survival (OS). We hypothesize that 3-year OS rate will improve to 70% for NIVO-CABO compared to 60% for NIVO alone; to achieve 85% power with a two-sided alpha of 0.05 and exponential distribution, 696 patients will be randomized. Accounting for 30% patients with either CR or PD, and 5% dropout from toxicity, up to 1046 pts will be enrolled. Key secondary endpoints include PFS, 12-month CR rate, ORR based on RECIST 1.1 and irRECIST criteria, and toxicity profiles. Quality of life will be assessed based on the FKSI-19, PROMIS-fatigue, and EQ5D-5L questionnaires. Biomarkers associated with CR and association of IL-6 with treatment benefit will be assessed. Other tissue-based and plasma-based biomarkers are planned. Enrollment will begin this year. Support from UG1CA189823, U24CA196171; https://acknowledgments.alliancefound.org . Clinical trial information: NCT03793166.

TPS504 Background: Patients with high-risk MIBC have a poor prognosis. Radical cystectomy remains the standard treatment. Yet despite substantial improvements in surgical techniques, mortality from metastatic recurrence remains high. A large number of MIBC patients are ineligible for cisplatin-based chemotherapy or have persistent muscle-invasive disease despite neoadjuvant chemotherapy (NAC). Pembrolizumab, a PD-1 inhibitor, has demonstrated significant activity and is FDA-approved for patients with advanced/chemotherapy-refractory metastatic urothelial carcinoma. We hypothesize that pembrolizumab given post-cystectomy will improve overall survival (OS) and disease-free survival (DFS) in patients with high-risk MIBC. Methods: Patients must have histologically confirmed muscle-invasive urothelial carcinoma of the bladder or upper tract, have received NAC and have ≥ pT2 and/or pN+ at surgery or be cisplatin-ineligible and have ≥ pT3 and/or pN+ at surgery or have declined adjuvant cisplatin-based therapy and have ≥ pT3 and/or pN+ at surgery. Surgery could be radical cystectomy, nephrectomy, or ureterectomy. Patients are stratified by pathologic stage, central PD-L1 status, and prior NAC. Patients are randomized to receive pembrolizumab 240 mg every 3 weeks for 1 year, or observation. The dual primary objectives are to determine DFS and OS. Secondary objectives are to determine DFS and OS in PD-L1-positive and -negative patients and assess safety. Correlative objectives are to determine whether 12 immune gene signatures, tumor molecular subtypes, diversity of T-cell receptor (TCR) clonotypes, persistence of TCR clonotypes, tumor and neoantigen burden, HLA subtypes, and plasma HGF and VEGF levels with IL-10 and IL-17 are associated with OS and DFS. Quality of Life Correlative objectives are to compare health-related quality of life as assessed by the EORTC QLQ-C30. Clinical trial information: NCT03244384.

Abstract This abstract was not presented at the symposium.