First-line talazoparib with enzalutamide in HRR-deficient metastatic castration-resistant prostate cancer: the phase 3 TALAPRO-2 trial.

Preclinical evidence has suggested an interplay between the androgen receptor, which largely drives the growth of prostate cancer cells, and poly(ADP-ribose) polymerase. This association provides a rationale for their co-inhibition for the treatment of metastatic castration-resistant prostate cancer (mCRPC), an area of unmet medical need. The phase 3 TALAPRO-2 study investigated combining the poly(ADP-ribose) polymerase inhibitor talazoparib with enzalutamide versus enzalutamide alone as first-line treatment of mCRPC. Patients were prospectively assessed for tumor alterations in DNA damage response genes involved in homologous recombination repair (HRR). Two cohorts were enrolled sequentially: an all-comers cohort that was enrolled first (cohort 1; N = 805 (169 were HRR-deficient)), followed by an HRR-deficient-only cohort (cohort 2; N = 230). We present results from the alpha-controlled primary analysis for the combined HRR-deficient population (N = 399). Patients were randomized in a 1:1 ratio to talazoparib or placebo, plus enzalutamide. The primary endpoint, radiographic progression-free survival, was met (median not reached at the time of the analysis for the talazoparib group versus 13.8 months for the placebo group; hazard ratio, 0.45; 95% confidence interval, 0.33 to 0.61; P < 0.0001). Data for overall survival, a key secondary endpoint, are immature but favor talazoparib (hazard ratio, 0.69; 95% confidence interval, 0.46 to 1.03; P = 0.07). Common adverse events in the talazoparib group were anemia, fatigue and neutropenia. Combining talazoparib with enzalutamide significantly improved radiographic progression-free survival in patients with mCRPC harboring HRR gene alterations, supporting talazoparib plus enzalutamide as a potential first-line treatment for these patients. ClinicalTrials.gov Identifier: NCT03395197 .

Pembrolizumab and Enzalutamide in Patients with Abiraterone Acetate-Pretreated Metastatic Castration-Resistant Prostate Cancer: Cohort C of the Phase 1b/2 KEYNOTE-365 Study.

BACKGROUND: Limited responses have been observed in patients treated with enzalutamide after disease progression on abiraterone for metastatic castration-resistant prostate cancer (mCRPC), but androgen receptor signaling impacts T-cell function. OBJECTIVE: To evaluate the efficacy and safety of pembrolizumab plus enzalutamide in mCRPC. DESIGN, SETTING, AND PARTICIPANTS: Patients in cohort C of the phase 1b/2 KEYNOTE-365 study, who received ≥4 wk of treatment with abiraterone acetate in the prechemotherapy mCRPC state and experienced treatment failure or became drug-intolerant, were included. INTERVENTION: Pembrolizumab 200 mg intravenously every 3 wk plus enzalutamide 160 mg orally once daily. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary endpoints were safety, the confirmed prostate-specific antigen (PSA) response rate, and the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors version 1.1 on blinded independent central review (BICR). Secondary endpoints included radiographic progression-free survival (rPFS) on BICR and overall survival (OS). RESULTS AND LIMITATIONS: A total of 102 patients received pembrolizumab plus enzalutamide. Median follow-up was 51 mo (interquartile range 37-56). The confirmed PSA response rate was 24% (95% confidence interval [CI] 16-33%). The confirmed ORR was 11% (95% CI 2.9-25%; 4/38 patients; two complete responses). Median rPFS was 6.0 mo (95% CI 4.1-6.3). Median OS was 20 mo (95% CI 17-24). Treatment-related adverse events (TRAEs) occurred in 94 patients (92%); grade 3-5 TRAEs occurred in 44 patients (43%). The incidence of treatment-related rash was higher with combination therapy than expected from the safety profile of each drug. One patient (1.0%) died of a TRAE (cause unknown). Study limitations include the single-arm design. CONCLUSIONS: Pembrolizumab plus enzalutamide had limited antitumor activity in patients who received prior abiraterone treatment without previous chemotherapy for mCRPC, with a safety profile consistent with the individual profiles of each agent. PATIENT SUMMARY: Pembrolizumab plus enzalutamide showed limited antitumor activity and manageable safety in patients with metastatic castration-resistant prostate cancer. The KEYNOTE-365 trial is registered on ClinicalTrials.gov as NCT02861573.

Talazoparib plus enzalutamide in men with first-line metastatic castration-resistant prostate cancer (TALAPRO-2): a randomised, placebo-controlled, phase 3 trial.

BACKGROUND: Co-inhibition of poly(ADP-ribose) polymerase (PARP) and androgen receptor activity might result in antitumour efficacy irrespective of alterations in DNA damage repair genes involved in homologous recombination repair (HRR). We aimed to compare the efficacy and safety of talazoparib (a PARP inhibitor) plus enzalutamide (an androgen receptor blocker) versus enzalutamide alone in patients with metastatic castration-resistant prostate cancer (mCRPC). METHODS: TALAPRO-2 is a randomised, double-blind, phase 3 trial of talazoparib plus enzalutamide versus placebo plus enzalutamide as first-line therapy in men (age ≥18 years [≥20 years in Japan]) with asymptomatic or mildly symptomatic mCRPC receiving ongoing androgen deprivation therapy. Patients were enrolled from 223 hospitals, cancer centres, and medical centres in 26 countries in North America, Europe, Israel, South America, South Africa, and the Asia-Pacific region. Patients were prospectively assessed for HRR gene alterations in tumour tissue and randomly assigned (1:1) to talazoparib 0·5 mg or placebo, plus enzalutamide 160 mg, administered orally once daily. Randomisation was stratified by HRR gene alteration status (deficient vs non-deficient or unknown) and previous treatment with life-prolonging therapy (docetaxel or abiraterone, or both: yes vs no) in the castration-sensitive setting. The sponsor, patients, and investigators were masked to talazoparib or placebo, while enzalutamide was open-label. The primary endpoint was radiographic progression-free survival (rPFS) by blinded independent central review, evaluated in the intention-to-treat population. Safety was evaluated in all patients who received at least one dose of study drug. This study is registered with ClinicalTrials.gov (NCT03395197) and is ongoing. FINDINGS: Between Jan 7, 2019, and Sept 17, 2020, 805 patients were enrolled and randomly assigned (402 to the talazoparib group and 403 to the placebo group). Median follow-up for rPFS was 24·9 months (IQR 21·9-30·2) for the talazoparib group and 24·6 months (14·4-30·2) for the placebo group. At the planned primary analysis, median rPFS was not reached (95% CI 27·5 months-not reached) for talazoparib plus enzalutamide and 21·9 months (16·6-25·1) for placebo plus enzalutamide (hazard ratio 0·63; 95% CI 0·51-0·78; p<0·0001). In the talazoparib group, the most common treatment-emergent adverse events were anaemia, neutropenia, and fatigue; the most common grade 3-4 event was anaemia (185 [46%] of 398 patients), which improved after dose reduction, and only 33 (8%) of 398 patients discontinued talazoparib due to anaemia. Treatment-related deaths occurred in no patients in the talazoparib group and two patients (<1%) in the placebo group. INTERPRETATION: Talazoparib plus enzalutamide resulted in clinically meaningful and statistically significant improvement in rPFS versus standard of care enzalutamide as first-line treatment for patients with mCRPC. Final overall survival data and additional long-term safety follow-up will further clarify the clinical benefit of the treatment combination in patients with and without tumour HRR gene alterations. FUNDING: Pfizer.

Pembrolizumab plus Olaparib in Patients with Metastatic Castration-resistant Prostate Cancer: Long-term Results from the Phase 1b/2 KEYNOTE-365 Cohort A Study.

BACKGROUND: Pembrolizumab and olaparib have shown single-agent activity in patients with previously treated metastatic castration-resistant prostate cancer (mCRPC). OBJECTIVE: To evaluate the efficacy and safety of pembrolizumab plus olaparib in mCRPC. DESIGN, SETTING, AND PARTICIPANTS: Cohort A of the phase 1b/2 KEYNOTE-365 study enrolled patients with molecularly unselected, docetaxel-pretreated mCRPC whose disease progressed within 6 mo of screening. INTERVENTION: Pembrolizumab 200 mg intravenously every 3 wk plus olaparib 400-mg capsule or 300-mg tablet orally twice daily. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary endpoints were safety, confirmed prostate-specific antigen (PSA) response rate, and objective response rate (ORR) as per Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1, by blinded independent central review. The secondary endpoints included radiographic progression-free survival (rPFS) and overall survival (OS). RESULTS AND LIMITATIONS: Of 104 enrolled patients, 102 were treated. The median age was 70 yr (interquartile range [IQR], 65-76), and 59 patients (58%) had measurable disease as per RECIST v1.1. The median time from the first dose to database cutoff was 24 mo (IQR, 22-47). The confirmed PSA response rate was 15%. The confirmed ORR was 8.5% (five partial responses) for patients with measurable disease. The median rPFS was 4.5 mo (95% confidence interval [CI], 4.0-6.5) and median OS was 14 mo (95% CI, 10.4-18.2). Clinical activity was consistent across the programmed death ligand 1 (PD-L1)-positive and homologous recombination repair mutation subgroups. Treatment-related adverse events (TRAEs) occurred in 93 patients (91%). Grade 3-5 TRAEs occurred in 49 patients (48%). Six deaths (5.9%) were due to adverse events; two (myocardial infarction and unknown cause) were attributed to treatment. Limitations of the study include the single-arm design. CONCLUSIONS: Pembrolizumab plus olaparib had a safety profile consistent with the profiles of the individual agents and demonstrated antitumor activity in previously treated patients with molecularly unselected, docetaxel-pretreated mCRPC. PATIENT SUMMARY: Pembrolizumab plus olaparib showed antitumor activity and expected safety in patients with metastatic castration-resistant prostate cancer.

Everolimus and zoledronic acid in patients with renal cell carcinoma with bone metastases: a randomized first-line phase II trial.

BACKGROUND: Bone metastases from renal cell carcinoma (RCC) are a major cause of morbidity. Post hoc analysis has suggested that bone turnover markers can identify patients at risk of skeletal-related events (SREs) among those receiving zoledronic acid. This study sought to evaluate the effect on bone metastases of everolimus alone compared with everolimus plus zoledronic acid. PATIENTS AND METHODS: Thirty treatment-naive patients with RCC and ≥ 1 bone metastases were randomized 1:1 to everolimus (10 mg daily) versus everolimus plus zoledronic acid (4 mg intravenously 4-weekly). Bone-specific assessments were performed at baseline and at weeks 1, 4, 8, and 12. Treatment was continued on allocated arm until progression per RECIST 1.1 (Response Evaluation Criteria in Solid Tumors, version 1.1). The primary outcome measure was urine N-telopeptide (uNTX) level, with secondary measures of plasma C-telopeptide (CTX), quality of life (Functional Assessment of Cancer Therapy-Bone Pain [FACT-BP], Brief Pain Inventory [BPI]), progression-free survival (PFS), SREs, and safety. RESULTS: After 12 weeks, reduction in mean uNTX and CTX on everolimus plus zoledronic acid relative to everolimus was 68.4% (95% CI, 60.1%-74.9%; P < .0001) and 76.2% (95% CI, 67.3%-82.7%; P < .0001), respectively. There was no evidence of a difference for FACT-BP (P = .5), but evidence was favorable for BPI Severity (P = .05) and BPI Interference (P = .06). Median PFS was 7.5 months (95% CI, 3.4-11.2) on everolimus plus zoledronic acid and 5.4 months (95% CI, 3.2-6.3) on everolimus (P = .009). Median time to first SRE was 9.6 months (95% CI, 4.3-15.5) on everolimus plus zoledronic acid and 5.2 months (95% CI, 1.6-8.2) on everolimus (P = .03). CONCLUSION: In this RCC population, the addition of zoledronic acid to everolimus significantly reduced bone resorption markers and may prolong tumor control.

Analysis of molecular cytogenetic changes in metastatic renal cell carcinoma in the setting of everolimus treatment: a pilot project.

BACKGROUND: The mTOR inhibitors have improved outcomes for patients with metastatic renal cell carcinoma (mRCC) but the duration of benefit is variable. Currently there are no predictive biomarkers for preselecting patients who are more likely to benefit from these agents. We undertook an exploratory translational study evaluating molecular cytogenetic changes in the context of outcomes from treatment with everolimus. PATIENTS AND METHODS: Ten patients with clear cell mRCC treated with everolimus were enrolled. Pretreatment tissue specimens were analyzed for molecular cytogenetic changes using fluorescence in situ hybridization and progression-free survival (PFS) data were obtained. Gene probes chosen for this analysis were: Von Hippel Lindau, fragile histidine triad, fibroblast growth factor receptor (FGFR) 1, FGFR3, PDGFß, PDGFRß, epidermal growth factor receptor, and myelocytomatosis viral oncogene. RESULTS: Median PFS was 8.75 months. Two patients with the longest PFS (28 months and 23 months) had gain of PDGFß and PDGFRß. This was also observed in 3 other patients who had a PFS of 11.5 months, 8 months, and 5.5 months, respectively. Cytogenetic evolution was observed between primary and metastatic specimens. CONCLUSION: PDGFß and PDGFRß gene status might be of relevance to everolimus therapy. Further research evaluating the utility of these potential biomarkers is required.