Grubb, Robert L.

TPS277 Background: Despite a growing number of treatment options for first-line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Co-inhibition of androgen receptor (AR) and PARP is a promising therapeutic strategy that leverages synthetic lethality induced by impaired double-strand DNA repair. Two phase III studies have shown improvement in radiographic progression-free survival (rPFS) in HRR-mutant pts with abiraterone + PARPi combinations vs abiraterone alone. However, the results in HRR-wild type pts are conflicting, with only one of the studies demonstrating a benefit with the abiraterone + PARPi combination. ENZ + RUCA has shown an acceptable safety profile & no significant drug-drug interactions (S-DDI) in a phase 1b trial. This allows its evaluation in mCRPC. Methods: CASPAR (A031902) is a phase 3 study in which 984 pts will be randomized on a 1:1 basis to ENZ plus RUCA/PBO. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue is available). Treatment will be continued until disease progression and crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or non-measurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, and no medications with S-DDI with ENZ/RUCA. Hierarchical co-primary endpoints are overall survival (OS) and rPFS. The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 and 21 months in control and combination arms, respectively), and 80% power to detect an HR of 0.80 in OS (median OS of 32 and 40 months, respectively). Key secondary endpoints are rPFS and OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; and differences in adverse events and quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF), and EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA testing for HRR gene alterations. Enrollment began in July 2021 & the study is available for participation to all US-NCTN sites. Clinical trial information: NCT04455750 .

TPS5107 Background: Despite a growing number of treatment options for first line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Androgen receptor (AR) signaling inhibition increases genomic instability with double-strand DNA breaks & co-inhibition of AR & PARP induces synthetic lethality in multiple preclinical models. Homologous recombination repair (HRR) gene aberrations do not appear to be necessary for this synergy as demonstrated in a ph 3 clinical trial of abiraterone & olaparib where this combination improved radiographic progression-free survival (rPFS) in HRR-wild-type pts compared with abiraterone alone. A ph 1b trial has since shown that enzalutamide plus rucaparib has acceptable safety profile & no significant drug-drug interactions (S-DDI). Methods: CASPAR/A031902 (NCT04455750) is a ph 3 study in which 984 pts will be randomized 1:1 to enzalutamide plus rucaparib or placebo. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted-exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue available). Treatment will be continued until disease progression & crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or nonmeasurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, & no medications with S-DDI with enzalutamide/rucaparib. Hierarchical co-primary endpoints are rPFS & overall survival (OS). The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 & 21 months in control & combination arms, respectively) & 80% power to detect an HR of 0.80 in OS (median OS of 32 & 40 months, respectively). Key secondary endpoints are rPFS & OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; & differences in adverse events & quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF) & EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA-based testing for alterations in HRR genes. Enrollment to CASPAR began in July 2021 & the study is available for participation to all US-NCTN sites with a projected enrollment of 3 years. Support: U10CA180821, U10CA180882, U24CA196171; U10CA180888. Clinical trial information: NCT04455750.

TPS194 Background: Despite a growing number of treatment options for first line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Androgen receptor (AR) signaling inhibition increases genomic instability with double-strand DNA breaks & co-inhibition of AR & PARP induces synthetic lethality in multiple preclinical models. Homologous recombination repair (HRR) gene aberrations do not appear to be necessary for this synergy as demonstrated in a ph 2 clinical trial of abiraterone & olaparib where this combination improved radiographic progression-free survival (rPFS) in HRR-wild-type pts compared with abiraterone alone. A ph 1b trial has since shown that enzalutamide plus rucaparib has acceptable safety profile & no significant drug-drug interactions (S-DDI). Methods: CASPAR/A031902 (NCT04455750) is a ph 3 study in which 984 pts will be randomized 1:1 to enzalutamide plus rucaparib or placebo. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted-exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue available). Treatment will be continued until disease progression & crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or nonmeasurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, & no medications with S-DDI with enzalutamide/rucaparib. Hierarchical co-primary endpoints are rPFS & overall survival (OS). The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 & 21 months in control & combination arms, respectively) & 80% power to detect an HR of 0.80 in OS (median OS of 32 & 40 months, respectively). Key secondary endpoints are rPFS & OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; & differences in adverse events & quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF) & EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA-based testing for alterations in HRR genes. Enrollment to CASPAR began in July 2021 & the study is available for participation to all US-NCTN sites with a projected enrollment of 3 years. Support: U10CA180821, U10CA180882, U24CA196171; U10CA180888; Clovis Oncology; http://acknowledgments.alliancefound.org Clinical trial information: NCT04455750.

BackgroundDecision aids (DAs) can improve knowledge for prostate cancer treatment. However, the relative effects of DAs delivered within the clinical encounter and in more diverse patient populations are unknown. A multicenter cluster randomized controlled trial with a 2×2 factorial design was performed to test the effectiveness of within‐visit and previsit DAs for localized prostate cancer, and minority men were oversampled.MethodsThe interventions were delivered in urology practices affiliated with the NCI Community Oncology Research Program Alliance Research Base. The primary outcome was prostate cancer knowledge (percent correct on a 12‐item measure) assessed immediately after a urology consultation.ResultsFour sites administered the previsit DA (39 patients), 4 sites administered the within‐visit DA (44 patients), 3 sites administered both previsit and within‐visit DAs (25 patients), and 4 sites provided usual care (50 patients). The median percent correct in prostate cancer knowledge, based on the postvisit knowledge assessment after the intervention delivery, was as follows: 75% for the pre+within‐visit DA study arm, 67% for the previsit DA only arm, 58% for the within‐visit DA only arm, and 58% for the usual‐care arm. Neither the previsit DA nor the within‐visit DA had a significant impact on patient knowledge of prostate cancer treatments at the prespecified 2.5% significance level (P = .132 and P = .977, respectively).ConclusionsDAs for localized prostate cancer treatment provided at 2 different points in the care continuum in a trial that oversampled minority men did not confer measurable gains in prostate cancer knowledge.

e24176 Background: Decision aids for prostate cancer treatment can improve knowledge, but the relative effect of pre-consultation and within-consultation DAs is not known. Methods: We conducted a parallel design, 2-by-2 factorial, 4-arm, cluster-RCT in urology practices affiliated with the NCI’s Alliance research base. We compared patient knowledge immediately after consultation (%12-item% correct) intervention arms compared to usual care. We used mixed effects regression modeling to assess effect of interventions on knowledge adjusting for site-clustering, race/ethnicity (non-Hispanic White; Other), age (years), clinical stage (T1-3), PSA, and Gleason score. Results: 15 of 21 randomized centers accrued 158 pts from Nov 2017 to June 2019. The arm delivering both DAs (n = 3 sites) recruited 25 pts. The pre-consultation DA arm (n = 4 sites) recruited 39 pts. The within-consultation DA arm (n = 4 sites) recruited 44 pts. The no DA arm (n = 4 sites) accrued 50 pts. Overall, mean age was 64; 54% were AA; 73% had T1 stage; median Gleason = 7; and median PSA = 7. The combined DAs group, followed by pre-consultation reported higher median knowledge (75% and 67%, respectively). The within-consultation and no DA arms both reported median knowledge scores (58%). Within arm, inter-site standard deviations in mean knowledge scores ranged from 0.164 in in the pre-consultation arm to 0.232 in the usual care arm. Neither pre-consultation nor within-consultation DAs had statistically significant effects (p = .15 and p = .99, respectively). Pre-specified adjusted difference [97.5% CIs], comparing the pre-consultation DA and the within-consultation DA with the control was 9.4% [-7.3%, 26.2%] and -0.4% [-16.9%, 16.1%], respectively. Intra-cluster correlation (ICC) coefficient was high (.24). No interaction effects were identified (p = .98). A post-hoc analysis comparing any DA vs usual care found a mean adjusted difference [95% CI] of 5.6% [-8.5%, 19.8%] (p = 0.40), 63.9% for any DA and 58.3% for usual care. Conclusions: Possible knowledge gains associated with some DAs for early prostate cancer were obscured by larger-than-expected intra-cluster correlation effects associated with the primary outcome. How interventions were used was not measured. Support:UG1CA189823; https://acknowledgments.alliancefound.org ; R01 MD008934-06. Clinical trial information: NCT03103321 .