Prostate-specific Antigen Response Rate Research Articles

Effects of metformin and statins on outcomes in men with castration-resistant metastatic prostate cancer: Secondary analysis of COU-AA-301 and COU-AA-302

BackgroundThe associations of metformin and statins with overall survival (OS) and prostate specific antigen response rate (PSA-RR) in trials in metastatic castration-resistant prostate cancer remain unclear. ObjectiveTo determine whether metformin or statins ± abiraterone acetate plus prednisone/prednisolone (AAP) influence OS and PSA-RR. Design, setting and participantCOU-AA-301 and COU-AA-302 patients were stratified by metformin and statin use. Cox proportional hazards models were used to estimate hazards ratio (HR) stratified by concomitant medications, and a random effects model was used to pool HR. We compared PSA-RR using Chi χ2 test. ResultsIn COU-AA-301-AAP, metformin was associated with improved PSA-RR (41.1% versus 28.6%) but not prolonged OS. In COU-AA-301-placebo-P, there was no association between metformin and prolonged OS or PSA-RR. In COU-AA-302-AAP, metformin was associated with prolonged OS (adjHR 0.69, 95% CI 0.48–0.98) and improved PSA-RR (72.7% versus 60.0%). In COU-AA-302-P, metformin was associated with prolonged OS (adjHR 0.66, 95% CI 0.47–0.93). In pooled analysis, OS was prolonged among those treated with metformin (pooled HR 0.77, 95% CI 0.62–0.95).In COU-AA-301-AAP, statins were associated with an improved OS (adjHR 0.76, 95% CI 0.62–0.93), while there was no difference in COU-AA-301-P. There was no association with statins and OS in either COU-AA-302 groups. When pooling HR, OS was prolonged among those treated with statins (pooled HR 0.78, 95% CI 0.68–0.88). ConclusionWithin the limitations of post-hoc sub-analyses, metformin and statins are associated with a prolonged OS and increased PSA-RR, particularly in combination with AAP.

Pembrolizumab Plus Docetaxel and Prednisone in Patients with Metastatic Castration-resistant Prostate Cancer: Long-term Results from the Phase 1b/2 KEYNOTE-365 Cohort B Study

BackgroundPatients with metastatic castration-resistant prostate cancer (mCRPC) frequently receive docetaxel after they develop resistance to abiraterone or enzalutamide and need more efficacious treatments. ObjectiveTo evaluate the efficacy and safety of pembrolizumab plus docetaxel and prednisone in patients with mCRPC. Design, setting, and participantsThe trial included patients with mCRPC in the phase 1b/2 KEYNOTE-365 cohort B study who were chemotherapy naïve and who experienced failure of or were intolerant to ≥4 wk of abiraterone or enzalutamide for mCRPC with progressive disease within 6 mo of screening. InterventionPembrolizumab 200 mg intravenously (IV) every 3 wk (Q3W), docetaxel 75 mg/m2 IV Q3W, and prednisone 5 mg orally twice daily. Outcome measurements and statistical analysisThe primary endpoints were safety, the prostate-specific antigen (PSA) response rate, and the objective response rate (ORR) according to Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST v1.1) by blinded independent central review (BICR). Secondary endpoints included time to PSA progression; the disease control rate (DCR) and duration of response (DOR) according to RECIST v1.1 by BICR; ORR, DCR, DOR, and radiographic progression-free survival (rPFS) according to Prostate Cancer Working Group 3–modified RECIST v1.1 by BICR; and overall survival (OS). Results and limitationsAmong 104 treated patients, 52 had measurable disease. The median time from allocation to data cutoff (July 9, 2020) was 32.4 mo, during which 101 patients discontinued treatment, 81 (78%) for disease progression. The confirmed PSA response rate was 34% and the confirmed ORR (RECIST v1.1) was 23%. Median rPFS and OS were 8.5 mo and 20.2 mo, respectively. Treatment-related adverse events (TRAEs) occurred in 100 patients (96%). Grade 3–5 TRAEs occurred in 46 patients (44%). Seven AE-related deaths (6.7%) occurred (2 due to treatment-related pneumonitis). Limitations of the study include the single-arm design and small sample size. ConclusionsPembrolizumab plus docetaxel and prednisone demonstrated antitumor activity in chemotherapy-naïve patients with mCRPC treated with abiraterone or enzalutamide for mCRPC. Safety was consistent with profiles for the individual agents. Further investigation is warranted. Patient summaryWe evaluated the efficacy and safety of the anti-PD-1 antibody pembrolizumab combined with the chemotherapy drug docetaxel and the steroid prednisone for patients with metastatic prostate cancer resistant to androgen deprivation therapy , and who never received chemotherapy. The combination showed antitumor activity and manageable safety in this patient population.This trial is registered on ClinicalTrials.gov as NCT02861573.

Clinical Outcome and Prognostic Variables of Second-line Therapy for Patients With Castration-resistant Prostate Cancer After Failure of First-line Androgen Receptor Axis-targeted Therapy.

Despite the rapid introduction of androgen receptor-targeted agents (ARTA) into clinical practice for castration-resistant prostate cancer (CRPC), the optimal treatment strategy after first-line ARTA remains unclear. The object of this study was to clarify clinical outcomes of second-line therapy for CRPC after first-line ARTA. The medical records of 130 consecutive patients with CRPC with disease progression during first-line ARTA and who started second-line therapy at our Institution between 2014 and 2020 were analyzed. A total of 130 patients with CRPC were identified. Ninety patients underwent ARTA-ARTA treatment, and 40 patients underwent ARTA-docetaxel treatment. The median observation period after second-line ARTA or docetaxel administration was 14.2 months. The prostate-specific antigen response rates overall, and after second-line ARTA, and docetaxel were 26.8%, 24.7%, and 31.6%, respectively. The median progression-free survival (PFS) and 1- and 2-year PFS rates of second-line therapy were 7.9 months and 34.6% and 15.4%, respectively. The median overall survival (OS) and 1- and 2-year OS rates were 27.4 months and 81.8%, and 54.9%, respectively. Multivariate analyses for OS disclosed that a C-reactive protein over the upper limit of normal and time from first-line ARTA to progression under 12 months were associated with shorter OS. Prostate-specific antigen response, PFS and OS of second-line therapy were not significantly different between second-line ARTA and docetaxel. There was no significant difference in OS between ARTA-ARTA and ARTA-docetaxel groups in the present study, suggesting that second-line ARTA might be the preferred treatment after initial failure of ARTA.

Real-World Prostate-Specific Antigen Response and Treatment Adherence of Apalutamide in Patients With Non-Metastatic Castration-Resistant Prostate Cancer

ObjectiveTo describe prostate-specific antigen (PSA) response and treatment adherence, overall and stratified by race, for patients with non-metastatic castration-resistant prostate cancer (nmCRPC) treated with apalutamide. MethodsElectronic medical records representing 63 urology practices from the United States were used to conduct this study. Patients with ≥2 apalutamide prescription fills and ≥12 months of prior prostate cancer management were identified. Patients were followed from apalutamide initiation until a switch to another antineoplastic treatment, death, or end of data availability (October 4, 2019). PSA response (≥50% decline from baseline PSA) and apalutamide adherence rates are described for the overall nmCRPC population treated and also stratified by race (Black and non-Black cohorts). ResultsOverall, 193 patients with nmCRPC were initiated on apalutamide. Thirty-three patients were Black (17.1%), 138 were non-Black (71.5%), and the remaining had an unknown racial background. The mean baseline PSA level for the overall, Black, and non-Black cohorts, was 7.0 ng/mL, 10.5 ng/mL, and 5.6 ng/mL, respectively. At 12 months of follow-up, PSA response was 86.0%, 93.1%, and 85.9% for the overall, Black, and non-Black cohorts, respectively. During a mean follow-up period of 333 days, 352 days, and 326 days, adherence was 93.6%, 90.1%, and 94.5% for the overall, Black and non-Black cohorts, respectively. ConclusionThis real-world study of patients with nmCRPC initiated on apalutamide showed that PSA response was robust and consistent with clinical trial data. Moreover, both Black and non-Black patients demonstrated high treatment adherence.

Outcome of Patients with PSMA PET/CT Screen Failure by VISION Criteria and Treated with 177Lu-PSMA Therapy: A Multicenter Retrospective Analysis.

The aim of the study was to assess the outcome of patients with metastatic castration-resistant prostate cancer treated with 177Lu-prostate-specific membrane antigen (PSMA) who would have been a screen failure (SF) in the VISION trial based on PSMA PET/CT criteria. Methods: We conducted a retrospective multicenter cohort study on 301 patients with metastatic castration-resistant prostate cancer treated with 177Lu-PSMA. The patients were classified into eligible (VISION-PET-E) and SF (VISION-PET-SF) groups on the basis of the baseline PSMA PET/CT results. Prostate-specific antigen (PSA) response rates, PSA progression-free survival, and overall survival were compared. Results: Of 301 patients, 272 (90.4%) and 29 (9.6%) were VISION-PET-E and VISION-PET-SF, respectively. The VISION-PET-SF patients had a worse rate of ≥50% PSA decline (21% vs. 50%, P = 0.005) and PSA progression-free survival (2.1 vs. 4.1 mo, P = 0.023) and tended to have a shorter overall survival (9.6 vs. 14.2 mo. P = 0.16) than the VISION-PET-E patients. Conclusion: The VISION-PET-SF patients had worse outcomes than the VISION-PET-E patients. Our cohort did not include preexcluded patients (10%-15%) by local site assessments. Thus, 20%-25% of the patients may be SFs in unselected populations. Refinements in patient selection for 177Lu-PSMA are needed to optimize outcomes.

Enzalutamide versus abiraterone plus prednisolone before chemotherapy for Japanese castration-resistant prostate cancer patients: An investigator-initiated, multicenter, randomized controlled trial.

122 Background: Enzalutamide and abiraterone plus prednisolone demonstrated improvement of survival for castration-resistant prostate cancer (CRPC). However, it remains quite unclear which agent is better in terms of efficacy and safety for Asian patients. Methods: An investigator-initiated, multicenter, randomized controlled trial was conducted in Japan. CRPC patients before chemotherapy were randomly assigned to the enzalutamide or the abiraterone plus prednisolone arm (1:1). The primary endpoint is time to prostate-specific antigen (PSA) progression and secondary endpoints include PSA response rate (≥50% decline from baseline), overall survival, radiographic progression-free survival, and safety assessment. Results: Between February 20, 2015 and July 30, 2019, 203 patients were enrolled. After randomization, 92 in the enzalutamide and 92 in the abiraterone plus prednisolone arm were treated and analyzed. Time to PSA progression was not significantly different between arms (median 21.2 and 11.9 months in the enzalutamide and the abiraterone plus prednisolone arm, respectively; hazard ration 0.81, 95% CI 0.51-1.27, p = 0.1732). There was a significant difference in PSA response rate between arms (72% and 57% in the enzalutamide and the abiraterone plus prednisolone arm, respectively, p = 0.0425). There were no significant differences in overall and radiographic progression-free survival between arms (median 32.9 and 35.5months in the enzalutamide and the abiraterone plus prednisolone arm, respectively; hazard ration 1.17, 95% CI 0.72-1.88, p = 0.5290 and median 17.6 and 14.0 months in the enzalutamide and the abiraterone plus prednisolone arm, respectively; hazard ration 0.92, 95% CI 0.63-1.34, p = 0.6532). Grade ≥3 of adverse events were observed in 11% and 21% in the enzalutamide and the abiraterone plus prednisolone arm, respectively ( p = 0.1044). Conclusions: Enzalutamide did not show any survival benefits compared with abiraterone plus prednisolone but showed better PSA response rate with no significant differences of severe adverse event rate for Japanese CRPC patients. Our data suggest that antecedent use of enzalutamide to abiraterone plus prednisolone have potentially clinical benefits in Asian CRPC populations. Clinical trial information: UMIN000015529.

Phase 1 study of JNJ-69086420, an actinium-225-labeled antibody targeting human kallikrein-2, for advanced prostate cancer.

TPS206 Background: Radioligand therapy for metastatic castration resistant prostate cancer (mCRPC) has been shown to prolong survival, delay disease progression, and improve quality of life, raising hopes that these gains will be amplified with even more cancer-specific targets and more powerful radioligands. Human kallikrein-related peptidase 2 (hK2) is a tumor-associated member of the kallikrein family that shares significant homology to prostate-specific antigen and is minimally expressed in normal non-prostate tissues. JNJ-69086420 (JNJ-420; 225Ac-DOTA-h11B6 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]), is a first-in-class radioimmunotherapy targeted to hK2 antigen. In a phase 0 study of [111In]-DOTA-h11B6, patients (pts) with mCRPC (progressed on standard therapies), treatment with a single dose of [111In]-DOTA-h11B6 (2 mg) with/without 8 mg h11B6, demonstrated safety, good tumor localization, nominal normal-organ uptake, and no difference in PK between 2 and 10 mg antibody mass (Morris et al. J Clin Oncol. 2021 39:6 suppl, 122). We have initiated the first-in-human study to assess the safety, pharmacokinetics (PK), pharmacodynamic (PD), and clinical activity of Ac-225 radiolabeled JNJ-420, to determine its recommended phase 2 dose (RP2D) in adults with advanced PC. Methods: This open-label, multicenter, phase 1 study will recruit approximately 50 men (aged ≥18 years) with advanced PC across dose escalation (Part 1) and expansion (Part 2) parts. Key eligibility criteria: mCRPC with histologic confirmation of adenocarcinoma, Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, adequate organ function based on hematology and serum chemistry, and 1 or more prior novel androgen receptor-targeted therapies (prior chemotherapy acceptable). Key exclusion criteria: prior treatment with radium/strontium/samarium/radioconjugate therapy, superscan findings as protocol defined, active central nervous system metastases. In Part 1, men will receive intravenous (IV) injection of 50 μCi/ 2 mg JNJ-420 (once every 8 weeks) with one or multiple doses; escalation of dose levels to be based on dose limiting toxicities (DLTs) evaluation, until RP2D identification. In Part 2, JNJ-420 is to be given at one of the RP2D(s) determined in Part 1. Primary endpoint is safety (incidence and severity [grading per NCI-CTCAE V5.0] of AEs including DLTs). Secondary endpoints include prostate specific antigen response rate, overall response rate (PCWG3 modified RECIST 1.1 criteria), PK, PD, immunogenicity, and biomarker analyses. Enrollment began in Dec 2020; as of Sep 2021, 4 sites have been initiated and 14 pts enrolled; currently, dose escalation is ongoing. Clinical trial information: NCT04644770.

A phase Ib, open-label study evaluating the safety and efficacy of ipatasertib + rucaparib in patients with metastatic castration-resistant prostate cancer (mCRPC).

95 Background: mCRPC remains an incurable disease with unmet need for improved therapies. PARP inhibition has demonstrated antitumor activity, and preclinical studies suggest synergy between PARP and AKT inhibition. This phase Ib trial (NCT03840200) sought to determine the maximum tolerated dose of PARP inhibitor rucaparib (ruca) with AKT inhibitor ipatasertib (ipat) and explore early safety and efficacy in patients (pts) with mCRPC. Methods: The study had 2 parts: a part 1 dose-escalation phase (cohort [C]1: ipat 300 mg QD + ruca 400 mg BID; C2a: ipat 300 mg QD + ruca 600 mg BID; C2b ipat 400 mg QD + ruca 400 mg BID; C3: ipat 400 mg QD + ruca 600 mg BID) in unselected pts with mCRPC or advanced breast or ovarian cancer, and a Part 2 dose-expansion phase in pts with mCRPC whose previous androgen deprivation therapy failed. The primary safety endpoints were AEs and dose-limiting toxicities, with the goal of identifying a recommended phase II dose (RP2D). The primary efficacy endpoint was prostate-specific antigen (PSA) response (PSA reduction of ≥ 50%) in pts with mCRPC. Secondary efficacy endpoints included ORR per RECIST 1.1, radiographic PFS (rPFS) per Prostate Cancer Working Group 3 and OS in pts with mCRPC. We assessed homologous recombination deficiency (HRD), PIK3CA/ AKT1/ PTEN status and other alterations by next-generation sequencing. Results: Part 1 enrolled 21 pts: 17 with mCRPC, 3 with ovarian cancer and 1 with breast cancer (C1 [n=8], C2a [n=6] and C2b [n=7], C3 [not opened]). Ipat 400 mg QD + ruca 400 mg BID was the selected RP2D. 30 pts enrolled in Part 2, so 37 pts with mCRPC (C2b + Part 2) received the RP2D (median follow-up 93 days). All grade AEs occurred in 37 pts (100%), serious AEs in 8 pts (22%) and AEs leading to treatment modification in 26 pts (70%). The most frequent AEs (all grade and grade 3, respectively) were diarrhea (35 [95%] and 2 [5%]); asthenia (24 [65%] and 4 [11%]); and nausea (24 [65%] and 2 [5%]). There was 1 grade 4 AE (anemia) and no grade 5 AEs. See the table for efficacy data. In biomarker subgroups, the PSA response rate was 50% (3/6) in pts with HRD tumors vs 25% (4/16) in pts with HR-proficient tumors, and 14% (1/7) vs 40% (6/15) in pts with PIK3CA/ AKT1/ PTEN–altered or intact tumors, respectively. Conclusions: The combination of ipat and ruca was well tolerated but did not show clinically relevant antitumor activity in pts with mCRPC, including in predefined biomarker subpopulations. Clinical trial information: NCT03840200. [Table: see text]

KEYNOTE-365 cohorts E and F: Phase 1b/2 study of pembrolizumab + lenvatinib combination therapy in patients with adenocarcinoma metastatic castration-resistant prostate cancer (mCRPC) or treatment-emergent neuroendocrine mCRPC (t-NE).

TPS215 Background: Standard of care for noncurative adenocarcinoma mCRPC is docetaxel or the next-generation hormonal agents (NHAs) abiraterone and enzalutamide. However, approximately 20% of patients develop t-NE after treatment for adenocarcinoma mCRPC; t-NE is associated with shorter survival, and it has no standard of care beyond combination platinum chemotherapy. The vascular endothelial growth factor (VEGF)/fibroblast growth factor receptor (FGFR) inhibitor lenvatinib inhibits proliferation and angiogenesis in preclinical models of adenocarcinoma prostate cancer. The phase 2 KEYNOTE-199 trial showed some antitumor activity with pembrolizumab monotherapy in docetaxel-pretreated patients with adenocarcinoma mCRPC. VEGF/FGFR inhibition combined with PD-1 inhibition may have enhanced benefit in mCRPC, for adenocarcinoma and possibly as a new treatment option for t-NE. Methods: KEYNOTE-365 (NCT02861573) is a nonrandomized, open-label, multicohort, phase 1b/2 trial designed to evaluate different pembrolizumab combination therapies in several patient populations with mCRPC. Cohort E will enroll patients with confirmed adenocarcinoma of the prostate without small cell histology, per investigator. Cohort F will enroll patients with t-NE (≥1% neuroendocrine cells in a recent biopsy specimen confirmed by central histology review). Each cohort will include patients who previously received docetaxel treatment for mCRPC. Prior treatment with ≤2 NHAs (for hormone-sensitive metastatic prostate cancer [mHSPC] or mCRPC) and 1 other chemotherapy for mCRPC is permitted. Additionally, enrollment in cohort F requires prostate cancer progression within 6 months of starting an NHA (for mHSPC or mCRPC) and within < 6 cycles of docetaxel for mCRPC. Each cohort will enroll 40-100 patients with Eastern Cooperative Oncology Group performance status score of 0 or 1. Both cohorts will receive pembrolizumab 200 mg IV every 3 weeks + oral lenvatinib 20 mg once daily until disease progression, withdrawal of consent, prespecified alanine aminotransaminase or aspartate aminotransaminase level increase, or other discontinuation event. Primary end points are safety and tolerability, prostate-specific antigen (PSA) response rate, and objective response rate (ORR) per RECIST v1.1 by blinded independent central review (BICR). Secondary end points include time to PSA progression; ORR and radiographic progression-free survival per Prostate Cancer Working Group 3 (PCWG3)–modified RECIST v1.1 by BICR; duration of response and disease control rate per RECIST v1.1 and PCWG3-modified RECIST v1.1 by BICR; and overall survival. These cohorts of KEYNOTE-365 are enrolling in Australia, Germany, New Zealand, Spain, and the United States. Clinical trial information: NCT02861573.

KEYNOTE-365 cohorts G and H: Phase 1b/2 study of pembrolizumab + vibostolimab combination therapy in patients with adenocarcinoma metastatic castration-resistant prostate cancer (mCRPC) or treatment-emergent neuroendocrine mCRPC (t-NE).

TPS204 Background: Treatment options are limited for patients with mCRPC that progresses after treatment with next-generation hormonal agents (NHAs)—such as enzalutamide and abiraterone acetate—or docetaxel. Approximately 20% of patients with adenocarcinoma mCRPC that progresses on androgen deprivation therapy develop t-NE mCRPC, which is associated with shortened overall survival (OS). The PD-1 inhibitor pembrolizumab showed antitumor activity as monotherapy in docetaxel-pretreated patients with adenocarcinoma mCRPC in the phase 2 KEYNOTE-199 trial. The T-cell immunoreceptor with Ig and ITIM domains (TIGIT) inhibitor vibostolimab showed antitumor activity when combined with pembrolizumab in pretreated patients with several tumor types in a phase 1 dose-escalation study. Combining PD-1 and TIGIT inhibition might have enhanced benefit in mCRPC, potentially both adenocarcinoma and t-NE. Methods: KEYNOTE-365 (NCT02861573) is a nonrandomized, open-label, multicohort, phase 1b/2 trial designed to evaluate the efficacy and safety of several pembrolizumab combination therapies in patients with mCRPC. Patients enrolled in cohort G will have confirmed adenocarcinoma of the prostate without small cell histology, per the investigator. Cohort H will enroll patients with t-NE (≥1% neuroendocrine cells in a recent biopsy specimen confirmed by central histology review). Each cohort will include patients who previously received docetaxel treatment for mCRPC. Prior treatment with ≤2 NHAs (for hormone-sensitive metastatic prostate cancer [mHSPC] or mCRPC) and 1 other chemotherapy for mCRPC is permitted. Enrollment in cohort H requires prostate cancer progression within 6 months of starting an NHA (for mHSPC or mCRPC) and within < 6 cycles of docetaxel for mCRPC. Each cohort will enroll 40-100 patients with Eastern Cooperative Oncology Group performance status score 0 or 1. Both cohorts will receive MK-7684A, a coformulation of pembrolizumab 200 mg and vibostolimab 200 mg, IV every 3 weeks. Treatment will continue until disease progression, withdrawal of consent, or other discontinuation event. Primary end points are safety and tolerability, prostate-specific antigen (PSA) response rate, and objective response rate (ORR) per RECIST v1.1 by blinded independent central review (BICR). Secondary end points include time to PSA progression; ORR and radiographic progression-free survival per Prostate Cancer Working Group 3 (PCWG3)–modified RECIST v1.1 by BICR; duration of response and disease control rate per RECIST v1.1 and PCWG3-modified RECIST v1.1 by BICR; and OS. These cohorts of KEYNOTE-365 are enrolling in Australia, Germany, New Zealand, Spain, and the United States. Clinical trial information: NCT02861573.

KEYNOTE-365 cohort I: Phase 1b/2 study of pembrolizumab combined with platinum-containing chemotherapy and chemotherapy alone for treatment-emergent neuroendocrine prostate carcinoma (t-NE).

TPS218 Background: In previously treated adenocarcinoma metastatic castration-resistant prostate cancer (mCRPC), approximately 20% of patients develop t-NE PC, which is aggressive with short overall survival (OS). t-NE PC treatment includes platinum-containing chemotherapy because of t-NE’s histologic, biologic, and clinical similarity to small cell/NE lung cancer. In the open-label, multicohort, phase 1b/2 KEYNOTE-365 study (NCT02861573), pembrolizumab, when combined with several agents for treatment of adenocarcinoma mCRPC, showed clinical activity and acceptable safety. To identify new treatment options for t-NE mCRPC, cohort I will help to evaluate platinum-containing chemotherapy alone or combined with pembrolizumab for patients with t-NE. Methods: Cohort I of the KEYNOTE-365 study will enroll patients with t-NE (≥1% neuroendocrine cells in a recent biopsy specimen confirmed by central histology review) and prior docetaxel treatment for mCRPC. Prior treatment with ≤2 next-generation hormonal agents (NHAs) for metastatic hormone-sensitive prostate cancer (mHSPC) or mCRPC and 1 other chemotherapy for mCRPC is permitted. Additionally, enrollment in cohort I requires previous prostate cancer progression within 6 months of starting an NHA (mHSPC or mCRPC) and within < 6 cycles of docetaxel for mCRPC. Each arm will enroll 40-100 patients with Eastern Cooperative Oncology Group performance status (ECOG PS) score of 0 or 1. Eligible patients will be randomly assigned 1:1 to receive pembrolizumab 200 mg IV on day 1 of each cycle every 3 weeks + carboplatin AUC of 5 IV on day 1 + etoposide 100 mg/m2 IV on days 1, 2, and 3 of each 21-day cycle for 4 cycles (arm 1) or the same chemotherapy regimen without pembrolizumab (arm 2). Pembrolizumab treatment will continue for up to 2 years until disease progression, unacceptable toxicity, or withdrawal of consent. Patients will be stratified by ECOG PS score (0 vs 1). Primary end points are safety and tolerability, prostate-specific antigen (PSA) response rate, and objective response rate (ORR) per RECIST v1.1 by blinded independent central review (BICR). Secondary end points include time to PSA progression; duration of response (DOR) and disease control rate (DCR) per RECIST v1.1 by BICR; ORR, DOR, DCR, and radiographic progression-free survival per Prostate Cancer Working Group 3–modified RECIST v1.1 by BICR; and OS. End points will be summarized for each arm without formal hypothesis testing. This cohort of KEYNOTE-365 is enrolling in Australia, Germany, New Zealand, Spain, and the United States. Clinical trial information: NCT02861573.

Abiraterone, Orteronel, Enzalutamide and Docetaxel: Sequential or Combined Therapy?

Objective: To summarize the current therapeutic status using chemotherapeutic agent docetaxel and endocrine therapeutic agents (ARAT, abiraterone, orteronel or enzalutamide) for the treatment of metastatic castration-resistant prostate cancer (mCRPC), including sequential therapy and combined therapy, to promote the consensus on the optimal regimen for achieving superior treatment efficacy. Methods: Through literature search in PubMed, articles with the following relevant keywords were collected and anlyzed: CRPC, abiraterone, orteronel and enzalutamide, median survival, overall survival, prostate specific antigen (PSA), PSA response rate and median radiologic progression-free survival. Results: Fifty-eight articles were obtained and analyzed in this review. These articles included androgen axis-targeting agents after docetaxel, docetaxel after androgen axis-targeting agents, Triple sequential and combination therapy, covering four current drugs for mCRPC treatment: docetaxel, abiraterone, orteronel, and enzalutamide. It was found that there may be some cross-resistance between androgen axis-targeting agents, which will reduce the efficacy of subsequent drug treatment. Although neither of the studies of using combination therapy showed serious drug toxicity, the efficacy of sequential therapy was not as good as expected. Most adverse reactions after treatment were reported to be level 1–2. Conclusion: Based on the results of the current studies, abiraterone followed by enzalutamide treatment is the best sequential treatment for most docetaxel-naïve patients. This treatment achieves not only good OS, but also PFS and PSA response rates. In addition, for patients who have previously failed docetaxel treatment, enzalutamide is the best choice as the subsequent treatment.

Efficacy and safety of Androgen Deprivation Therapy (ADT) combined with modified docetaxel chemotherapy versus ADT combined with standard docetaxel chemotherapy in patients with metastatic castration-resistant prostate cancer: study protocol for a multicentre prospective randomized controlled trial

BackgroundAndrogen deprivation therapy (ADT) combined with docetaxel chemotherapy is the standard treatment for metastatic castration-resistant prostate cancer (mCRPC) patients. However, mCRPC patients are mainly frail elderly men, constantly accompanied by comorbidities and showing poor tolerance to standard docetaxel chemotherapy. Some exploratory studies administering modified chemotherapy regimens have reported noninferior oncologic outcomes with fewer adverse events, yet most are retrospective or small studies, and prospective randomized controlled trials have rarely been conducted. Therefore, we designed this modified docetaxel chemotherapy regimen in patients with mCRPC, aiming to evaluate its efficacy and safety compared with the standard docetaxel chemotherapy regimen.MethodsThis is an open-label, multi-institutional, prospective, randomized non-inferiority trial. A total of 128 patients with mCRPC will be randomized to receive ADT combined with modified docetaxel chemotherapy (experimental group, n=64) or ADT combined with standard docetaxel chemotherapy (control group, n=64). Patients in the experimental group will receive a modified regimen with docetaxel 40 mg/m2 on the 1st day and 35 mg/m2 on the 8th day, repeated every 21 days. The primary endpoint is progression-free survival at 2 years. Secondary endpoints include overall survival, prostate-specific antigen response rate, pain response rate, toxicity and quality of life.DiscussionThe expected benefit for the patient in the experimental arm is noninferior efficacy with decreased toxicity and improved quality of life compared with that in the control arm. To the best of our knowledge, this will be the first multicentre prospective randomized study to assess the efficacy and safety of modified docetaxel chemotherapy in patients with mCRPC in China. The results of this trial may provide benefit to mCRPC patients, especially those with poor performance.Trial registrationchictr.org.cn Identifier: ChiCTR2100046636 (May 24, 2021). Ongoing study.

Improving power in PSA response analyses of metastatic castration-resistant prostate cancer trials

BackgroundTo determine how much an augmented analysis approach could improve the efficiency of prostate-specific antigen (PSA) response analyses in clinical practice. PSA response rates are commonly used outcome measures in metastatic castration-resistant prostate cancer (mCRPC) trial reports. PSA response is evaluated by comparing continuous PSA data (e.g., change from baseline) to a threshold (e.g., 50% reduction). Consequently, information in the continuous data is discarded. Recent papers have proposed an augmented approach that retains the conventional response rate, but employs the continuous data to improve precision of estimation.MethodsA literature review identified published prostate cancer trials that included a waterfall plot of continuous PSA data. This continuous data was extracted to enable the conventional and augmented approaches to be compared.ResultsSixty-four articles, reporting results for 78 mCRPC treatment arms, were re-analysed. The median efficiency gain from using the augmented analysis, in terms of the implied increase to the sample size of the original study, was 103.2% (IQR [89.8,190.9%]).ConclusionsAugmented PSA response analysis requires no additional data to be collected and can be performed easily using available software. It improves precision of estimation to a degree that is equivalent to a substantial sample size increase. The implication of this work is that prostate cancer trials using PSA response as a primary endpoint could be delivered with fewer participants and, therefore, more rapidly with reduced cost.

Neutropenia, neutrophilia, and neutrophil-lymphocyte ratio as prognostic markers in patients with metastatic castration-resistant prostate cancer.

Background and purpose:Chemotherapy-induced neutropenia and neutrophil-to-lymphocyte ratio (NLR) are potentially useful prognostic markers in patients with metastatic castration-resistant prostate cancer (mCRPC). This post hoc analysis investigated whether these markers can be utilized for dose considerations and evaluated the prognostic impact of leukocyte subtypes.Patients and methods:PROSELICA assessed the non-inferiority of cabazitaxel 20 mg/m2 (C20; n = 598) versus 25 mg/m2 (C25; n = 602) for overall survival (OS) in patients with mCRPC previously treated with docetaxel. The association of grade ⩾ 3 neutropenia, NLR, baseline neutrophilia and lymphopenia with OS, progression-free survival (PFS), and prostate-specific antigen response rate (PSArr) was investigated by an unplanned uni- and multivariate analyses.Results:PROSELICA confirmed the negative prognostic value of increased baseline NLR [⩾3, hazard ratio (HR) 1.40; p < 0.0001], but did not identify a subgroup of patients benefiting more from C20 or C25. In this post hoc analysis, patients who developed grade ⩾3 neutropenia (n = 673) had a significantly improved OS [∆OS = 2.7 months, HR = 0.78 (95% CI 0.68–0.89)] with the greatest advantage observed in patients with baseline neutrophilia [n = 85; 5.3 months, 0.60 (0.42–0.84)]. After adjustment for the Halabi criteria, neutropenia grade ⩾ 3 was the only biomarker that remained significantly associated with OS [ (HR 0.86 (0.75–0.98)], PFS [HR 0.78 (0.68–0.88)], and PSArr [odds ratio (OR) 1.82 (1.37–2.41)] while neutrophilia showed the strongest association with OS [1.53 (1.29–1.81)].Conclusions:Grade ⩾ 3 neutropenia was the only leukocyte-based biomarker associated with all key outcome parameters in mCRPC patients receiving cabazitaxel and might be able to overcome the negative prognostic effect of baseline neutrophilia.NCT number:NCT01308580

The association of AR-V7 with resistance to Abiraterone in metastatic castration-resistant prostate cancer

Background: This paper sought to investigate the association between androgen receptor splice variant 7 (AR-V7) status in circulating tumors cells (CTCs) and resistance to abiraterone (Abi) and docetaxel (Doc) in men with metastatic castration-resistant prostate cancer (mCRPC). Methods: This was a prospective clinical study, newly confirmed mCRPC patients who were randomized going to receive Abi or Doc with age ≥18 years were enrolled to detect the AR-V7 mRNA in CTCs. The association of AR-V7 status with Gleason Score, prostate specific antigen response rate (PSA RR), hormone-sensitive duration time (HSDT), time-to event outcomes, including PSA progression-free survival (PFS), clinical PFS, radiographic PFS and cancer-specific survival (CSS) was examined. Results: 139 patients with mCPRC were enrolled; 67 received Abi and 72 received Doc. The proportion of AR-V7-positive patients was 35.8% in Abi-treated patients and 34.7% in Doc-treated patients. Our results were as follows: (1) among men receiving Abi, AR-V7-positive patients had a higher Gleason Score (8.34 ± 1.03 vs. 7.29 ± 0.76, p = 0.012) and lower PSA RR (20.8% vs. 65.1%, p = 0.001) compared with AR-V7-negative patients; in a multivariable COX model, AR-V7 positivity was an independent risk factor for shorter PSA PFS (p = 0.012), clinical PFS (p = 0.036) and radiographic PFS (p = 0.028); (2) among men receiving Doc, AR-V7-positive patients also had a higher Gleason Score compared with AR-V7-negative patients (8.86 ± 0.66 vs. 7.57 ± 0.94, p &lt; 0.0001), but no differences in PSA RR, PSA PFS, clinical PFS, radiographic PFS or CSS were observed; (3) among AR-V7-positive patients, men receiving Abi had lower a PSA RR compared with men receiving Doc (20.8% vs. 48%, p = 0.046); in a multivariable COX model, Abi was an independent risk factor for shorter PSA PFS (p = 0.040) and clinical PFS (p = 0.046); (4) among AR-V7-negative patients, there were no differences in PSA RR, PSA PFS, clinical PFS, radiographic PFS or CSS between Abi- and Doc-treated patients. Conclusion: AR-V7-positive patients commonly have a higher Gleason Score than AR-V7 negative patients, and AR-V7 positivity is strongly associated with Abi resistance in mCRPC but is not associated with the effectiveness of Doc.

Oncological Response and Predictive Biomarkers for the Checkpoint Inhibitors in Castration-Resistant Metastatic Prostate Cancer: A Systematic Review and Meta-Analysis.

Recently, checkpoint inhibitors have been investigated in metastatic prostate cancer, however their overall effect is unclear and needs to be further investigated. Objectives: The aim of this systematic review is to investigate the oncological response of metastatic castration-resistant prostate cancer patients to immune checkpoint inhibitors. Methods: Based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement, a systematic review of the literature was conducted through online electronic databases and the American Society of Clinical Oncology (ASCO) Meeting Library. Eligible publications were selected after a staged screening and selection process. RevMan 5.4 software was employed to run the quantitative analysis and forest plots. Risk of bias assessment was conducted using the Cochrane tool and Newcastle–Ottawa Scale for the randomized and non-randomized trials, respectively. Results: From the 831 results retrieved, 8 studies including 2768 patients were included. There was no significant effect on overall survival (OS) (overall response (OR) = 0.98; Z = 0.42; p = 0.67). Meanwhile, progression-free survival (PFS) was significantly better with immune checkpoint inhibitors administration (OR = 0.85; Z = 3.9; p < 0.0001). The subgroup analysis for oncological outcomes based on programmed death ligand 1 (PD-L1) positivity status displayed no significant effect, except on prostate-specific antigen response rate (PSA RR) (OR = 3.25; Z = 2.29; p = 0.02). Based on DNA damage repair (DDR), positive patients had a significantly better PFS and a trend towards better OS and overall response rate (ORR); the ORR was 40% in positive patients compared to 20% in the negative patients (OR = 2.46; Z = 1.3; p = 0.19), while PSA RR was 23.5% compared to 14.3% (OR = 1.88; Z = 0.88; p = 0.38). Better PFS was clearly associated with DDR positivity (OR = 0.70; Z = 2.48; p = 0.01) with a trend towards better OS in DDR positive patients (OR = 0.71; Z = 1.38; p = 0.17). Based on tumor mutation burden (TMB), ORR was 46.7% with high TMB versus 8.8% in patients with low TMB (OR = 11.88; Z = 3.0; p = 0.003). Conclusions: Checkpoint inhibitors provide modest oncological advantages in metastatic castration-resistant prostate cancer. There are currently no good predictive indicators that indicate a greater response in some patients.

Response to Rucaparib in BRCA-Mutant Metastatic Castration-Resistant Prostate Cancer Identified by Genomic Testing in the TRITON2 Study.

The PARP inhibitor rucaparib is approved in the United States for patients with metastatic castration-resistant prostate cancer (mCRPC) and a deleterious germline and/or somatic BRCA1 or BRCA2 (BRCA) alteration. While sequencing of tumor tissue is considered the standard for identifying patients with BRCA alterations (BRCA+), plasma profiling may provide a minimally invasive option to select patients for rucaparib treatment. Here, we report clinical efficacy in patients with BRCA+ mCRPC identified through central plasma, central tissue, or local genomic testing and enrolled in TRITON2. Patients had progressed after next-generation androgen receptor-directed and taxane-based therapies for mCRPC and had BRCA alterations identified by central sequencing of plasma and/or tissue samples or local genomic testing. Concordance of plasma/tissue BRCA status and objective response rate and prostate-specific antigen (PSA) response rates were summarized. TRITON2 enrolled 115 patients with BRCA+ identified by central plasma (n = 34), central tissue (n = 37), or local (n = 44) testing. Plasma/tissue concordance was determined in 38 patients with paired samples and was 47% in 19 patients with a somatic BRCA alteration. No statistically significant differences were observed between objective and PSA response rates to rucaparib across the 3 assay groups. Patients unable to provide tissue samples and tested solely by plasma assay responded at rates no different from patients identified as BRCA+ by tissue testing. Plasma, tissue, and local testing of mCRPC patients can be used to identify men with BRCA+ mCRPC who can benefit from treatment with the PARP inhibitor rucaparib.

Four-year Prostate-specific Antigen Response Rate as a Predictive Measure in Intermediate-risk Prostate Cancer Treated With Ablative Therapies: The SPRAT Analysis

AimsThere is a lack of early predictive measures of outcome for patients with intermediate-risk prostate cancer (PCa) treated with stereotactic body radiotherapy (SBRT). The aim of the present study was to explore 4-year prostate-specific antigen response rate (4yPSARR) as an early predictive measure. Materials and methodsIndividual patient data from six institutions for patients with intermediate-risk PCa treated with SBRT between 2006 and 2016 with a 4-year (42–54 months) PSA available were analysed. Cumulative incidences of biochemical failure and metastasis were calculated using Nelson-Aalen estimates and overall survival was calculated using the Kaplan–Meier method. Biochemical failure-free survival was analysed according to 4yPSARR, with groups dichotomised based on PSA <0.4 ng/ml or ≥0.4 ng/ml and compared using the Log-rank test. A multivariable competing risk analysis was carried out to predict for biochemical failure and the development of metastases. ResultsSix hundred and thirty-seven patients were included, including 424 (67%) with favourable and 213 (33%) with unfavourable intermediate-risk disease. The median follow-up was 6.2 years (interquartile range 4.9–7.9). The cumulative incidence of biochemical failure and metastasis was 7 and 0.6%, respectively; overall survival at 6 years was 97%. The cumulative incidence of biochemical failure at 6 years if 4yPSARR <0.4 ng/ml was 1.7% compared with 27% if 4yPSARR ≥0.4 ng/ml (P < 0.0001). On multivariable competing risk analysis, 4yPSARR was a statistically significant predictor of biochemical failure-free survival (subdistribution hazard ratio 15.3, 95% confidence interval 7.5–31.3, P < 0.001) and metastasis-free survival (subdistribution hazard ratio 31.2, 95% confidence interval 3.1–311.6, P = 0.003). Conclusion4yPSARR is an encouraging early predictor of outcome in patients with intermediate-risk PCa treated with SBRT. Validation in prospective trials is warranted.

Nivolumab plus docetaxel in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer: results from the phase II CheckMate 9KD trial

BackgroundDocetaxel has immunostimulatory effects that may promote an immunoresponsive prostate tumour microenvironment, providing a rationale for combination with nivolumab (programmed death-1 inhibitor) for metastatic castration-resistant prostate cancer (mCRPC). MethodsIn the non-randomised, multicohort, global phase II CheckMate 9KD trial, 84 patients with chemotherapy-naive mCRPC, ongoing androgen deprivation therapy and ≤2 prior novel hormonal therapies (NHTs) received nivolumab 360 mg and docetaxel 75 mg/m2 every 3 weeks with prednisone 5 mg twice daily (≤10 cycles) and then nivolumab 480 mg every 4 weeks (≤2 years). The co-primary end-points were objective response rate (ORR) and prostate-specific antigen response rate (PSA50-RR; ≥50% decrease from baseline). ResultsThe confirmed ORR (95% confidence interval [CI]) was 40.0% (25.7–55.7), and the confirmed PSA50-RR (95% CI) was 46.9% (35.7–58.3). The median (95% CI) radiographic progression-free survival (rPFS) and overall survival (OS) were 9.0 (8.0–11.6) and 18.2 (14.6–20.7) months, respectively. In subpopulations with versus without prior NHT, the ORR was 38.7% versus 42.9%, the PSA50-RR was 39.6% versus 60.7%, the median rPFS was 8.5 versus 12.0 months and the median OS was 16.2 months versus not reached. Homologous recombination deficiency status or tumour mutational burden did not appear to impact efficacy. The most common any-grade and grade 3–4 treatment-related adverse events were fatigue (39.3%) and neutropenia (16.7%), respectively. Three treatment-related deaths occurred (1 pneumonitis related to nivolumab; 2 pneumonias related to docetaxel). ConclusionsNivolumab plus docetaxel has clinical activity in patients with chemotherapy-naïve mCRPC. Safety was consistent with the individual components. These results support further investigation in the ongoing phase III CheckMate 7DX trial. ClinicalTrials.gov registrationNCT03338790.