Prostate-specific Antigen Response Rate Research Articles

Biomarker-Directed Therapy in Black and White Men With Metastatic Castration-Resistant Prostate Cancer

Black men have higher incidence and mortality from prostate cancer. Whether precision oncology disparities affect Black men with metastatic castration-resistant prostate cancer (mCRPC) is unknown. To compare precision medicine data and outcomes between Black and White men with mCRPC. This retrospective cohort study used data collected by the Prostate Cancer Precision Medicine Multi-Institutional Collaborative Effort (PROMISE) consortium, a multi-institutional registry with linked clinicogenomic data, from April 2020 to December 2021. Participants included Black and White patients with mCRPC with molecular data. Data were analyzed from December 2021 to May 2023. Database-reported race and ethnicity. The primary outcome was the frequency of actionable molecular data, defined as the presence of mismatch repair deficiency (MMRD) or high microsatellite instability (MSI-H), homologous recombination repair deficiency, or tumor mutational burden of 10 mutations per megabase or greater. Secondary outcomes included the frequency of other alterations, the type and timing of genomic testing performed, and use of targeted therapy. Efficacy outcomes were prostate-specific antigen response rate, site-reported radiographic response, and overall survival. A total of 962 eligible patients with mCRPC were identified, including 204 Black patients (21.2%; median [IQR] age at diagnosis, 61 [55-67] years; 131 patients [64.2%] with Gleason scores 8-10; 92 patients [45.1%] with de novo metastatic disease) and 758 White patients (78.8%; median [IQR] age, 63 [57-69] years; 445 patients [58.7%] with Gleason scores 8-10; 310 patients [40.9%] with de novo metastatic disease). Median (IQR) follow-up from mCRPC was 26.6 (14.2-44.7) months. Blood-based molecular testing was more common in Black men (111 men [48.7%]) than White men (317 men [36.4%]; P < .001). Rates of actionable alterations were similar between groups (65 Black men [32.8%]; 215 White men [29.1%]; P = .35), but MMRD or MSI-H was more common in Black men (18 men [9.1]) than White men (36 men [4.9%]; P = .04). PTEN alterations were less frequent in Black men than White men (31 men [15.7%] vs 194 men [26.3%]; P = .003), as were TMPRSS alterations (14 men [7.1%] vs 155 men [21.0%]; P < .001). No other differences were seen in the 15 most frequently altered genes, including TP53, AR, CDK12, RB1, and PIK3CA. Matched targeted therapy was given less frequently in Black men than White men (22 men [33.5%] vs 115 men [53.5%]; P = .008). There were no differences in response to targeted therapy or survival between the two cohorts. This cohort study of men with mCRPC found higher frequency of MMRD or MSI-H and lower frequency of PTEN and TMPRSS alterations in Black men compared with White men. Although Black men received targeted therapy less frequently than White men, no differences were observed in clinical outcomes.

Race and Treatment Outcomes in Patients With Metastatic Castration-Sensitive Prostate Cancer

Black patients present with more aggressive disease and experience higher mortality than White patients with prostate cancer. Race and social determinants of health influence prostate cancer-specific mortality and overall survival (OS); however, in a previous trial, Black patients did not have inferior outcomes compared with White patients, possibly because of equitable access to care available in a clinical trial setting. To compare differences in survival outcomes of patients with metastatic castration-sensitive prostate cancer (mCSPC) by race in a phase 3 trial with a large proportion of Black patients. This secondary analysis of patient-level data of a prospective phase 3 randomized clinical trial included patients with newly diagnosed mCSPC enrolled between March 1, 2013, and July 15, 2017. Analysis was conducted between December 2022 and February 2023. Patients receiving androgen deprivation therapy were randomized (1:1) to receive either orteronel 300 mg orally twice daily (experimental group) or bicalutamide 50 mg orally daily (control group). OS, with progression-free survival (PFS) as a secondary end point. Among 1313 participants, 135 (10%) identified as Black and 1077 (82%) as White, with an equal racial distribution between groups. Black patients were younger (median [IQR] age, 65.8 [60-70] vs 68.4 [62.5-74.1] years; P = .001) and had a higher median (IQR) baseline prostate-specific antigen response rate than White patients (54.7 [19.8-222.0] vs 26.7 [9.2-96.0] ng/mL; P < .001). At a median follow-up of 4.9 years, Black and White patients had similar median PFS (2.3 years; 95% CI, 1.8-1.4 years vs 2.9 years; 95% CI, 2.5-3.3 years; P = .71) and OS (5.5 years; 95% CI, 4.8-NR vs 6.3 years; 95% CI, 5.7-NR; P = .65). The multivariable analysis confirmed similar PFS and OS after adjusting for known prognostic factors. No interaction between race and treatment was observed. In this secondary analysis of a randomized clinical trial studying androgen deprivation therapy with first- or second-generation androgen receptor pathway inhibitors, both Black and White patients demonstrated similar OS and PFS. Equitable access to care may reduce historical differences in outcomes between Black and White patients with advanced prostate cancer. ClinicalTrials.gov Identifier: NCT01809691.

A Phase Ib, Open-label Study Evaluating the Safety and Efficacy of Ipatasertib plus Rucaparib in Patients with Metastatic Castration-resistant Prostate Cancer.

To report the safety and efficacy of ipatasertib (AKT inhibitor) combined with rucaparib (PARP inhibitor) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with second-generation androgen receptor inhibitors. In this two-part phase Ib trial (NCT03840200), patients with advanced prostate, breast, or ovarian cancer received ipatasertib (300 or 400 mg daily) plus rucaparib (400 or 600 mg twice daily) to assess safety and identify a recommended phase II dose (RP2D). A part 1 dose-escalation phase was followed by a part 2 dose-expansion phase in which only patients with mCRPC received the RP2D. The primary efficacy endpoint was prostate-specific antigen (PSA) response (≥50% reduction) in patients with mCRPC. Patients were not selected on the basis of tumor mutational status. Fifty-one patients were enrolled (part 1 = 21; part 2 = 30). Ipatasertib 400 mg daily plus rucaparib 400 mg twice daily was the selected RP2D, received by 37 patients with mCRPC. Grade 3/4 adverse events occurred in 46% (17/37) of patients, with one grade 4 adverse event (anemia, deemed related to rucaparib) and no deaths. Adverse events leading to treatment modification occurred in 70% (26/37). The PSA response rate was 26% (9/35), and the objective response rate per Response Criteria in Solid Tumors (RECIST) 1.1 was 10% (2/21). Median radiographic progression-free survival per Prostate Cancer Working Group 3 criteria was 5.8 months [95% confidence interval (CI), 4.0-8.1], and median overall survival was 13.3 months (95% CI, 10.9-not evaluable). Ipatasertib plus rucaparib was manageable with dose modification but did not demonstrate synergistic or additive antitumor activity in previously treated patients with mCRPC.

Safety and Efficacy of [177Lu]-PSMA-I&T Radioligand Therapy in Octogenarians with Metastatic Castration-Resistant Prostate Cancer: Report on 80 Patients over the Age of 80 Years.

177Lu-labeled prostate-specific membrane antigen (PSMA) radioligand therapy (RLT) is a new treatment option for metastatic castration-resistant prostate cancer (mCRPC). Its low toxicity profile favors use in elderly patients or in patients with critical comorbidities. The purpose of this analysis was to evaluate the efficacy and safety of [177Lu]-PSMA RLT in mCRPC patients at least 80 y old. Methods: Eighty mCRPC patients at least 80 y old underwent [177Lu]-PSMA-I&T RLT and were retrospectively selected. The patients were previously treated by androgen receptor-directed therapy, received taxane-based chemotherapy, or were chemotherapy-ineligible. The best prostate-specific antigen (PSA) response was calculated, as well as clinical progression-free survival (cPFS) and overall survival (OS). Toxicity data were acquired until 6 mo after the last treatment cycle. Results: Of 80 patients, 49 (61.3%) were chemotherapy-naïve and 16 (20%) had visceral metastases. The median number of previous mCRPC treatment regimens was 2. In total, 324 cycles (median, 4 cycles; range, 1-12) with a median cumulative activity of 23.8 GBq (interquartile range, 14.8-42.2) were applied. A PSA decline of 50% was achieved in 37 (46.3%) patients. Chemotherapy-naïve patients showed higher 50% PSA response rates than chemotherapy-pretreated patients (51.0% vs. 38.7%, respectively). Overall, median cPFS and OS were 8.7 and 16.1 mo, respectively. The median cPFS and OS of chemotherapy-naïve patients were significantly longer than those of chemotherapy-pretreated patients (10.5 vs. 6.5 mo and 20.7 vs. 11.8 mo, respectively, P < 0.05). A lower hemoglobin level and higher lactate dehydrogenase level at baseline were independent predictors of shorter cPFS and OS. Treatment-emergent grade 3 toxicities were anemia in 4 patients (5%), thrombocytopenia in 3 patients (3.8%), and renal impairment in 4 patients (5%). No nonhematologic grade 3 and no grade 4 toxicities were observed. The most frequent clinical side effects were grade 1-2 xerostomia, fatigue, and inappetence. Conclusion: [177Lu]-PSMA-I&T RLT in mCRPC patients at least 80 y old is safe and effective, comparable to previously published data on non-age-selected cohorts with a low rate of high-grade toxicities. Chemotherapy-naïve patients showed a better and longer response to therapy than taxane-pretreated patients. [177Lu]-PSMA RLT seems to be a meaningful treatment option for older patients.

The Impact of PSMA PET-Based Eligibility Criteria Used in the Prospective Phase II TheraP Trial in Metastatic Castration-Resistant Prostate Cancer Patients Undergoing Prostate-Specific Membrane Antigen-Targeted Radioligand Therapy.

Prostate-specific membrane antigen (PSMA) radioligand therapy (RLT) has shown encouraging results for treatment of metastatic castration-resistant prostate cancer (mCRPC) in the prospective, multicenter, randomized phase II TheraP study. The inclusion criteria for that study comprised a pretherapeutic 68Ga-PSMA-11 PET scan showing sufficient tumor uptake using a predefined threshold and the absence of 18F-FDG-positive, PSMA ligand-negative tumor lesions. However, the prognostic value of these PET-based inclusion criteria remains unclear. Therefore, we evaluated the outcome of mCRPC patients treated with PSMA RLT using TheraP as well as other TheraP-based PET inclusion criteria. Methods: First, patients were dichotomized into 2 groups whose PSMA PET scans did (TheraP contrast-enhanced PSMA [cePSMA] PET-positive) or did not (TheraP cePSMA PET-negative) fulfill the inclusion criteria of TheraP. Notably, unlike in TheraP, 18F-FDG PET was not performed on our patients. Prostate-specific antigen (PSA) response (PSA decline ≥ 50% from baseline), PSA progression-free survival, and overall survival (OS) were compared. Additionally, patients were further dichotomized according to predefined SUVmax thresholds different from those used in TheraP to analyze their potential impact on outcome as well. Results: In total, 107 mCRPC patients were included in this analysis (TheraP cePSMA PET-positive, n = 77; TheraP cePSMA PET-negative, n = 30). PSA response rates were higher in TheraP cePSMA PET-positive patients than in TheraP cePSMA PET-negative patients (54.5% vs. 20%, respectively; P = 0.0012). The median PSA progression-free survival (P = 0.007) and OS (P = 0.0007) of patients were significantly longer in the TheraP cePSMA PET-positive group than in the TheraP cePSMA PET-negative group. Moreover, being in the TheraP cePSMA PET-positive group was identified as a significant prognosticator of longer OS (P = 0.003). The application of different SUVmax thresholds for a single hottest lesion demonstrated no influence on outcome in patients eligible for PSMA RLT. Conclusion: Patient selection for PSMA RLT according to the inclusion criteria of TheraP led to a better treatment response and outcome in our preselected patient cohort. However, a relevant number of patients not fulfilling these criteria also showed substantial rates of response.

Rucaparib for the Treatment of Metastatic Castration-resistant Prostate Cancer Associated with a DNA Damage Repair Gene Alteration: Final Results from the Phase 2 TRITON2 Study

BackgroundInitial TRITON2 (NCT02952534) results demonstrated the efficacy of rucaparib 600 mg BID in patients with metastatic castration-resistant prostate cancer (mCRPC) associated with a BRCA1 or BRCA2 (BRCA) or other DNA damage repair (DDR) gene alteration. ObjectiveTo present the final data from TRITON2. Design, setting, and participantsTRITON2 enrolled patients with mCRPC who had progressed on one or two lines of next-generation androgen receptor–directed therapy and one taxane-based chemotherapy. Outcome measurements and statistical analysisThe primary endpoint was objective response rate (ORR; as per the modified Response Evaluation Criteria in Solid Tumor Version 1.1/Prostate Cancer Clinical Trials Working Group 3 criteria in patients with measurable disease by independent radiology review [IRR]); prostate-specific antigen (PSA) response rate (≥50% decrease from baseline [PSA50]) was a key secondary endpoint. Results and limitationsAs of July 27, 2021 (study closure), TRITON2 had enrolled 277 patients, grouped by mutated gene: BRCA (n = 172), ATM (n = 59), CDK12 (n = 15), CHEK2 (n = 7), PALB2 (n = 11), or other DDR gene (Other; n = 13). ORR by IRR was 46% (37/81) in the BRCA subgroup (95% confidence interval [CI], 35–57%), 100% (4/4) in the PALB2 subgroup (95% CI, 40–100%), and 25% (3/12) in the Other subgroup (95% CI, 5.5–57%). No patients within the ATM, CDK12, or CHEK2 subgroups had an objective response by IRR. PSA50 response rates (95% CI) in the BRCA, PALB2, ATM, CDK12, CHEK2, and Other subgroups were 53% (46–61%), 55% (23–83%), 3.4% (0.4–12), 6.7% (0.2–32%), 14% (0.4–58%), and 23% (5.0–54%), respectively. ConclusionsThe final TRITON2 results confirm the clinical benefit and manageable safety profile of rucaparib in patients with mCRPC, including those with an alteration in BRCA or select non-BRCA DDR gene. Patient summaryAlmost half of TRITON2 patients with BRCA-mutated metastatic castration-resistant prostate cancer had a complete or partial tumor size reduction with rucaparib; clinical benefits were also observed with other DNA damage repair gene alterations.

Prime-boost immunotherapeutic trial in men with biochemical recurrence after definitive local therapy for prostate cancer.

TPS5119 Background: VTP-850 is a heterologous prime-boost immunotherapeutic consisting of 2 nonreplicating viral-vectored components: ChAdOx1-PCAQ, based on an adenoviral vector, and MVA-PCAQ, based on a modified vaccinia virus Ankara (MVA) vector. Both components encode the same 4 prostate cancer antigens: prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), six transmembrane epithelial antigen of prostate 1 (STEAP1), and 5T4, an oncofetal antigen. Preclinical studies in inbred, outbred, and HLA-A2 transgenic mice show that VTP-850 is highly immunogenic. Immune responses were measured in splenocytes using IFN-γ ELISpot assay, multiparameter flow cytometry, and targeted in vivo killing assays. The results indicate that VTP-850 can elicit T cell responses to each of the 4 encoded antigens, with the responses to PSA of greatest magnitude in all mouse strains studied. Intravenous administration of the boost resulted in a 6-fold increase in the magnitude of antigen-specific T cells induced and increased in vivo killing relative to the intramuscular boosting route1. Methods: This is a first-in-human multicenter Phase 1/2 trial to evaluate safety, PSA response rate and duration, and immunogenicity of VTP-850 in men with biochemical recurrence of prostate cancer after definitive local therapy. Phase 1 (15-18 participants) will follow a 3+3 design to determine the recommended phase 2 regimen; dose level of both ChAdOx1-PCAQ and MVA-PCAQ, and route of administration of MVA-PCAQ (IM or IV). Phase 2 will consist of 2 stages. In Stage 1, 19 additional participants will be enrolled at the chosen Phase 2 regimen. If 4 or more of the 25 participants (including the 6 Phase 1 participants who received the same regimen) have a PSA response (defined as ≥50% reduction in serum PSA compared to baseline at any time, measured twice consecutively, at least 2 weeks apart), Stage 2 will enroll 100 additional participants. Participants will be followed for 6 months or until start of new therapy (e.g. ADT) or until development of metastatic disease. Participants who have a PSA response during the 6 months follow up will be followed for up to an additional 18 months. Patients who have undergone primary therapy for prostate cancer and have biochemical recurrence are eligible. Patients must have nonmetastatic (M0) disease; serum PSA of &gt; 0.3 ng/mL for participants with prior radical prostatectomy or serum PSA of 2 ng/mL above nadir for participants with prior external beam radiation or brachytherapy; PSA doubling time ≤12 months; and testosterone &gt; 75 ng/dL. They cannot have received ADT within 6 months prior to Day 1 and cannot have received prior chemotherapy, immunotherapy or experimental agent for prostate cancer. The trial is open in the USA, with sites in Spain and Italy planned to open later in 2023. 1. Vardeu A et al 2022. Clinical trial information: NCT05617040 .

Randomized placebo-controlled trial of intravenous vitamin C plus docetaxel in metastatic prostate cancer.

e17050 Background: Some phase I/II trials showed that combining high dose IV vitamin C with chemotherapies decreased toxicities and improved QoL in advanced cancers, while others failed to show benefits. While grade ¾ AEs are not typically a co-primary endpoint, they are a measure of cumulative toxicity. We investigated whether high-dose IV vitamin C could improve prostate-specific antigen (PSA) response rate and mitigate docetaxel toxicities in patients with metastatic castrate-resistant prostate cancer (mCRPC) receiving docetaxel. Methods: Patients were randomized (2:1) to receive docetaxel (75mg/m2 IV every 3 weeks) plus IV vitamin C (1g/kg) or placebo twice a week. The primary endpoints were PSA50 response by24 weeks and adverse events (AEs) of fatigue, nausea, bone pain, and anorexia. Secondary endpoints included overall survival (OS) and QoL measured by the Functional Assessment of Cancer Therapy-Prostate (FACT-P). Results: 50 patients were randomized, 47 received therapy (treatment N = 32, control N = 15), 3 untreated (withdrawal, elevated creatine, low hemoglobin). The median age was 74 years (range 45-85) and ECOG 1. The median PSA was 108.3 ng/mL (range: 0.3, 2102.3). The median number of chemotherapy cycles was 6 (IQR 3-8). The study was suspended after the pre-specified interim analysis for primary endpoints showed futility. The PSA50 response was 41% for treatment and 33% for control (P = 0.44). Grade 1-2 and grade 3-4 prespecified AEs occurred in 69% and 6% of treatment group patients versus 60% and 0% of control group patients (one-sided Cochran Armitage test, P =0.90). Diarrhea (72% vs 19%) and anemia (47% vs 25%) and neutropenia (22% vs 19%) are more frequent in the Vit C group. Compared with the control group, treatment group patients showed a trend towards shorter median OS. FACT-P was not significantly different at any timepoints. Conclusions: Initial concurrent high-dose IV vitamin C with docetaxel did not improve PSA response, toxicity, or clinical outcomes. MCRPC patients receiving docetaxel should be advised against seeking concurrent high-dose IV vitamin C. Clinical trial information: NCT02516670 .

Open-label study of darolutamide plus androgen-deprivation therapy (ADT) vs ADT in metastatic hormone-sensitive prostate cancer using an external control arm (ARASEC).

TPS5112 Background: Darolutamide (DARO) is a structurally distinct and highly potent androgen receptor inhibitor. In the phase 3 ARASENS study (NCT02799602) in patients (pts) with metastatic hormone-sensitive prostate cancer (mHSPC), DARO + ADT + docetaxel significantly reduced the risk of death by 32.5% vs ADT + docetaxel (hazard ratio 0.68; 95% confidence interval 0.57–0.80), with a favorable tolerability and safety profile. In the global (excluding US), phase 3 ARANOTE study (NCT04736199), DARO + ADT vs ADT alone is being evaluated in pts with mHSPC. ARASEC (NCT05059236) will complement ARANOTE by assessing DARO + ADT in US pts. As ADT alone is no longer an acceptable comparator in the US, the external control arm will be derived from the historical US CHAARTED study (NCT00309985). A real-world analysis of electronic health record data from pts with mHSPC (TIMES) indicated that there was minimal risk of historical time bias associated with the use of the external ADT alone arm from CHAARTED as a comparator for ARASEC (Shore N, et al . J Clin Oncol 2022;40(28 Suppl):Abstract 403). Methods: ARASEC is a phase 2, open-label, single-arm study enrolling pts with confirmed mHSPC and no prior systemic therapy. Pts will receive DARO 600 mg orally twice daily + ADT (luteinizing hormone-releasing hormone agonist/antagonist or orchiectomy). The external control arm will be derived from 394 pts with mHSPC treated with ADT alone in CHAARTED. To remove biases in evaluating outcomes that could arise due to differences in baseline profiles between arms, pts will be matched 1:1 using a propensity score (PS) summarizing baseline characteristics relevant to disease outcomes. Baseline variables will include age ( &lt; 70 vs ≥70 years), Eastern Cooperative Oncology Group performance status (0–1 vs 2), CHAARTED-defined extent of disease (low vs high volume + bone metastases only vs high volume + visceral metastases ± bone metastases), and prior therapy (yes vs no; as a proxy for recurrent vs de novo disease). Matching patients with scores within a narrow window across the cohorts will ensure that pts in CHAARTED are representative of pts in the DARO + ADT arm. The primary endpoint is progression-free survival (PFS), as defined in CHAARTED. Secondary endpoints include overall survival, radiographic PFS, time to CRPC, undetectable prostate-specific antigen response rate ( &lt; 0.2 ng/mL) at 6 months, and safety. Target enrollment for the DARO + ADT arm is 200 pts at 30 sites. The study will continue until either the event count threshold triggering the primary endpoint analysis has been met (161 PFS events) or all pts have been followed for ≥2 years, whichever occurs later. As of January 2023, 121 pts have been enrolled. A per-protocol, predefined matching exercise on the first 100 pts enrolled will be conducted to ensure that the planned sample size is adequate. Clinical trial information: NCT05059236 .

177Lu]Lu-PSMA-Radioligand Therapy Efficacy Outcomes in Taxane-Naïve Versus Taxane-Treated Patients with Metastatic Castration-Resistant Prostate Cancer: A Systematic Review and Metaanalysis.

Radioligand therapy (RLT) with 177Lu-prostate-specific membrane antigen (PSMA) inhibitors ([177Lu]Lu-PSMA) is currently approved for patients with metastatic castration-resistant prostate cancer (mCRPC) after progression with at least 1 taxane and 1 androgen-receptor-pathway inhibitor. However, the impact of prior chemotherapy on [177Lu]Lu-PSMA-RLT outcomes is debatable, with various studies showing inconsistent results. This study was conducted to precisely evaluate the impact of prior taxane chemotherapy on response and survival outcomes in mCRPC patients after [177Lu]Lu-PSMA-RLT. Methods: This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Searches in PubMed, Scopus, and Embase were made using relevant key words, and articles up to December 2022 were included. The endpoints included prostate-specific antigen (PSA) response rate (RR), progression-free survival, and overall survival (OS). Individual patient data were pooled when feasible. Univariate odds ratios (ORs) and hazard ratios (HRs) were extracted from the individual articles, and pooled estimates and 95% CIs were generated using metaanalysis. Results: Thirteen articles comprising 2,068 patients were included. In 6 articles (553 patients), taxane-naïve patients had significantly better odds of biochemical response after [177Lu]Lu-PSMA-RLT (pooled OR, 1.82; 95% CI, 1.21-2.71). Individual patient data metaanalysis for PSA RRs in 3 articles revealed a significantly higher PSA RR in the taxane-naïve versus taxane-treated patients (57.1% vs. 39.5%; difference, 17.6%; 95% CI, 5.6%-28.9%). Further, taxane-naïve status was also a predictor of significantly better progression-free survival (5 articles; 1,027 patients; pooled HR, 0.60; 95% CI, 0.51-0.69) and OS (8 articles; 1,594 patients; pooled HR, 0.54; 95% CI, 0.43-0.68) after [177Lu]Lu-PSMA-RLT. There was no evidence of publication bias. Conclusion: mCRPC patients with no prior taxanes had significantly better outcomes after [177Lu]Lu-PSMA-RLT than did taxane-treated patients. Further trials evaluating [177Lu]Lu-PSMA-RLT in the taxane-naïve setting are now required.

Proxalutamide in metastatic castration-resistant prostate cancer: Primary analysis of a multicenter, randomized, open-label, phase 2 trial.

We aim to assess the safety and efficacy of proxalutamide, a novel androgen receptor antagonist, for men with metastatic castration-resistant prostate cancer (mCRPC) in a multicenter, randomized, open-label, phase 2 trial. In our study, the enrolled mCRPC patients were randomized to 100, 200 and 300 mg dose groups at 1:1:1. The primary efficacy endpoint was prostate-specific antigen (PSA) response rate. The secondary endpoints included objective response rate (ORR), disease control rate (DCR) and time to PSA and radiographic progression. Safety and pharmacokinetics were also assessed. Finally, there were 108 patients from 17 centers being enrolled. By week 16, there were 13 (35.1%), 12 (36.4%) and 15 (42.9%) patients with confirmed 50% or greater PSA decline in 100 mg (n=37), 200 mg (n=33) and 300 mg (n=35) groups, respectively. Among the 19 patients with target lesions at study entry, three (15.8%) had a partial response and 12 (63.2%) had stable disease. The ORRs of 20.0%, 22.2%, 0% and DCRs of 80.0%, 88.9%, 60.0% were, respectively, achieved in 100, 200 and 300 mg groups. By the maximum follow-up time of 24 weeks, there were 42.6% and 10.2% of cases experiencing PSA progression and radiographic progression, respectively. Overall, adverse events (AEs) were experienced by 94.4% of patients, most of which were mild or moderate. There were 28 patients experiencing ≥grade 3 AEs. The most common AEs were fatigue (17.6%), anemia (14.8%), elevated AST (14.8%) and ALT (13.0%), decreased appetite (13.0%). These findings preliminarily showed the promising antitumor activity of proxalutamide in patients with mCRPC with a manageable safety profile. The proxalutamide dose of 200 mg daily is recommended for future phase 3 trial (Clinical trial registration no. CTR20170177).

MP11-16 PROSTATE-SPECIFIC ANTIGEN ANALYSES IN PROPEL: ABIRATERONE AND OLAPARIB VERSUS ABIRATERONE AND PLACEBO AS FIRST-LINE THERAPY FOR METASTATIC CASTRATION-RESISTANT PROSTATE CANCER

MP11-16 PROSTATE-SPECIFIC ANTIGEN ANALYSES IN PROPEL: ABIRATERONE AND OLAPARIB VERSUS ABIRATERONE AND PLACEBO AS FIRST-LINE THERAPY FOR METASTATIC CASTRATION-RESISTANT PROSTATE CANCER

Outcomes and prognostic predictors of Lu-177 PSMA radioligand therapy in metastatic castration-resistant prostate cancer (Asian Population Study).

Lutetium-177 (Lu-177) prostate-specific membrane antigen radioligand therapy (PSMA-RLT) is a promising therapy for metastatic castration-resistant prostate cancer (mCRPC), but there is limited data of its efficacy and safety in Asian population. We aim to explore the clinical outcomes of Lu-177 PSMA-RLT in this population. We evaluated 84 patients with progressive mCRPC receiving Lu-177 PSMA-RLT between 9 May 2018 and 21 February 2022. Lu-177-PSMA-I&T was administered at 6-8-week intervals. Primary end point was overall survival (OS), and secondary end points included prostate-specific antigen (PSA) progression-free survival (PFS), PSA response rate, clinical response, toxicity assessment, and prognostic indicators. The median OS and PSA PFS were 12.2 and 5.2 months, respectively. PSA decline of ≥50% was observed in 51.8% of patients. Patients achieving PSA response had longer median OS (15.0 vs. 9.5 months, p=.03) and PSA PFS (6.5 vs. 2.9 months, p<.001). Pain score improvement was seen in 19 out of 34 patients. A hematotoxicity of ≥grade 3 was observed in 13 out of 78 patients. Multivariable analyses showed that PSA velocity, alkaline phosphatase, hemoglobin (Hb), and the number of treatment cycles were independent prognostic indicators for OS. The retrospective design was the main limitation of the study. Our study demonstrated a similar safety and efficacy of Lu-177 PSMA-RLT in Asian mCRPC patients compared to the existing literature. A PSA decline ≥50% was associated with longer OS and PSA PFS. Several prognostic indicators for patient outcomes were also identified.

Outcome of patients with biochemical recurrence of prostate cancer after PSMA PET/CT-directed radiotherapy or surgery without systemic therapy

BackgroundRadiotherapy (RT) and surgery are potential treatment options in patients with biochemical recurrence (BCR) following primary prostate cancer treatment. This study examines the value of prostate-specific membrane antigen (PSMA) positron emission tomography/computed tomography (PET/CT)-informed surgery and RT in patients with BCR treated without systemic therapy.MethodsThis is a post-hoc subgroup analysis of a prospective clinical trial. Inclusion criteria were: histologically proven prostate cancer at initial curative-intent treatment, BCR after primary treatment with curative intent, having five or fewer lesions identified on [18F]DCFPyL PET/CT, and treatment with either PET/CT-directed RT or surgery without systemic therapy. The biochemical progression-free survival after PSMA ligand PET/CT-directed RT and surgery was determined. Uni- and multivariate Cox regression analyses were performed for the association of patients’ characteristics, tumor-specific variables, and PSMA PET/CT imaging results with biochemical progression at the last follow-up.ResultsFifty-eight patients (30 in surgery and 28 in radiotherapy groups) met the inclusion criteria. A total of 87 PSMA-positive lesions were detected: 16 local recurrences (18.4%), 54 regional lymph nodes (62.1%), 6 distant lymph nodes (6,8%), and 11 osseous lesions (12.7%). A total of 85.7% (24 of 28) and 70.0% (21 of 30) of patients showed a ≥ 50% decrease in prostate-specific antigen (PSA) levels after RT and surgery, respectively. At a median follow-up time of 21 months (range, 6–32 months), the median biochemical progression-free survival was 19 months (range, 4 to 23 months) in the radiotherapy group, as compared with 16.5 months (range, 4 to 28 months) in the surgery group. On multivariate Cox regression analysis, the number of PSMA positive lesions (2–5 lesions compared to one lesion), and the anatomic location of the detected lesions (distant metastasis vs. local relapse and pelvic nodal relapse) significantly correlated with biochemical progression at the last follow-up, whereas other clinical, tumor-specific, and imaging parameters did not.ConclusionsThis study suggests that RT or surgery based on [18F]DCFPyL PET/CT are associated with high PSA response rates. The number and site of lesions detected on the PSMA PET/CT were predictive of biochemical progression on follow-up. Further studies are needed to assess the impact of targeting these sites on patient relevant outcomes.Trial registrationRegistered September 14, 2016; NCT02899312; https://clinicaltrials.gov/ct2/show/NCT02899312

Nadir Prostate-specific Antigen as an Independent Predictor of Survival Outcomes: A Post Hoc Analysis of the PROSPER Randomized Clinical Trial.

This post hoc analysis of PROSPER evaluated the relationship between depth of PSA decline and clinical outcomes in enzalutamide-treated men with nonmetastatic castration-resistant prostate cancer. PROSPER was an international, randomized, double-blind, placebo-controlled, phase 3 trial that demonstrated significantly improved metastasis-free survival and overall survival with androgen deprivation therapy plus enzalutamide vs placebo. A total of 905 enzalutamide-treated men were included in this post hoc analysis. Metastasis-free survival (primary endpoint) and overall survival (secondary endpoint) were evaluated for 4 mutually exclusive subgroups defined by PSA decline: <50% (reference); ≥50% to <90%; ≥90%, nadir ≥0.2 ng/mL; and ≥90%, nadir <0.2 ng/mL. Medians and 95% confidence intervals were determined using a 12-month landmark analysis; hazard ratios and P values were based on an unstratified Cox proportional analysis model. In enzalutamide-treated men, PSA declines of <50%, ≥50% to <90%, ≥90% with nadir ≥0.2 ng/mL, and ≥90% with nadir <0.2 ng/mL were associated with median metastasis-free survival in months (95% confidence intervals) of 22.1 (14.8-not reached), 34.2 (29.4-not reached), 36.6 (33.4-not reached), and not reached, respectively, and overall survival in months (95% confidence intervals) of 40.8 (31.7-44.9), 54.4 (49.0-67.0), 64.3 (63.4-not reached), and not reached, respectively. There was a statistically significant correlation between greater depth of PSA decline and improved clinical outcomes, suggesting a previously underappreciated relationship between changes in PSA levels and clinical outcomes in nonmetastatic castration-resistant prostate cancer.

Efficacy and safety of apalutamide in patients with metastatic castration-resistant prostate cancer (GENESIS): protocol for a multicentre, open-label, single-arm clinical trial

IntroductionThis is a multicentre, open-label, single-arm clinical trial to evaluate the efficacy and safety of apalutamide in patients with metastatic castration-resistant prostate cancer.Methods and analysisThe trial will be performed at...

Prostate-specific antigen response after Abiraterone treatment in mCRPC: PSA as a predictor of overall survival

Abiraterone Acetate (AA) is an important agent in the treatment of advanced prostate cancer. It was primarily approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC) after failure of androgen deprivation therapy. There is still no available strong data regarding the impact of early decline of prostate-specific antigen (PSA) in the overall survival. The aim of this study was to evaluate the clinical efficacy of an early prostate-specific antigen response as a predictor of overall survival (OS) in metastatic castration-resistant prostate cancer when treated with Abiraterone Acetate. A dual center, retrospective, cohort study on patients diagnosed with mCRPC treated with abiraterone between 2013 and 2020 was performed. Primary end-point was to demonstrate the efficacy of AA, with the analysis of PSA decline, and the correlation with overall survival. The cohort analysis consisted of 84 patients with a median age of 71 ± 9 years. A PSA response of > 30% and > 50% at 60 and 90 days was associated with improved OS. Multivariate analysis revealed that a 60 day PSA decline of > 30% was predictive of overall survival. Median OS of diag-nosed mCRPC patients was 28 months. Docetaxel pre-treatment was not associated with longer OS. The median duration of drug exposure for patients submitted to AA was found to be 14 months. Early PSA response rate can offer clinically meaningful information and can be considered a surrogate of longer OS. A > 30% or > 50% prostate-specific antigen decline at 60 and 90 days provided an important low-cost clinical tool to predict subsequent events in mCRPC patients treated with abiraterone.

Nivolumab plus ipilimumab for the treatment of post-chemotherapy metastatic castration-resistant prostate cancer (mCRPC): Additional results from the randomized phase 2 CheckMate 650 trial.

22 Background: In preliminary analyses from the randomized phase 2, open-label CheckMate 650 trial, nivolumab (NIVO) 1 mg/kg (N1) plus ipilimumab (IPI) 3 mg/kg (I3) Q3W × 4 doses showed clinical activity in patients (pts) with post-chemotherapy (post-CT) mCRPC, particularly those with high tumor mutational burden (TMB), but early toxicity contributed to treatment discontinuations. Here, we report results from pts with post-CT mCRPC receiving alternative NIVO+IPI dosing regimens vs IPI alone vs cabazitaxel (CABA) in CheckMate 650. Methods: Newly enrolled pts previously treated with docetaxel for mCRPC were randomized 2:2:1:2 to cohorts D1 (NIVO 3 mg/kg [N3] + IPI 1 mg/kg [I1] Q3W × 4 doses then NIVO 480 mg Q4W), D2 (N1 Q3W × 8 doses + I3 Q6W × 4 doses then NIVO 480 mg Q4W), D3 (I3 Q3W × 4 doses), or D4 (CABA 20 or 25 mg/m2 Q3W + prednisone 10 mg × 10 doses). Crossover from cohorts D3 and D4 to cohort D1 was allowed after radiographic progressive disease. Outcomes included safety, objective response rate (ORR), prostate-specific antigen response rate (PSA-RR; confirmed PSA decline ≥ 50% from baseline), radiographic progression-free survival (rPFS) per blinded independent central review (BICR), and overall survival (OS). Associations between efficacy and TMB were assessed. Results: Overall, 259 pts were randomized (D1, n = 73; D2, n = 74; D3, n = 38; D4, n = 74). Median (range) follow-up for OS was 23.3 (6.0–31.5) months. In the NIVO+IPI cohorts (D1 and D2), median duration of therapy was 2.8 and 2.4 months; the median number of IPI doses received was 4 and 2, and 15% and 26% of pts discontinued due to study drug toxicity, respectively. Two pts died due to study drug toxicity (1 each in cohorts D1 and D2). Key safety and efficacy data are shown. Several pts in cohorts D1 and D2 showed notable reductions (75-100%) in tumor size and PSA. Approximately one-third of pts in cohorts D3 and D4 crossed over to D1. Based on preliminary analyses in small numbers of evaluable pts, there was no clear and consistent association between efficacy and tissue or blood TMB in the NIVO+IPI cohorts (D1 and D2). Conclusions: These results further support the clinical activity of NIVO+IPI in select pts with post-CT mCRPC. Detailed evaluations of the characteristics of responders to NIVO+IPI, including more expansive biomarker analyses, are warranted. Clinical trial information: NCT02985957 . [Table: see text]

The efficacy and adverse events of conventional and second-generation androgen receptor inhibitors for castration-resistant prostate cancer: A network meta-analysis.

Second-generation androgen receptor inhibitors (ARIs) have been developed and approved for treating castration-resistant prostate cancer (CRPC). There is a lack of direct comparison of the therapeutic effects and adverse events between the conventional ARI (bicalutamide) and three second-generation ARIs (enzalutamide, apalutamide and darolutamide). Our network meta-analysis evaluated therapeutic effects and adverse events of the conventional ARI (bicalutamide) and the second-generation ARIs in treating CRPC. We systematically searched the Pubmed, Cochrane library and Embase databases for studies published until October 2022 and only randomized clinical trials (RCTs) were included. The progression-free survival, prostate-specific antigen (PSA) progression-free survival, overall survival (PFS/PSA-PFS/OS), PSA response rate and relative adverse events (AEs) of CRPC patients were collected and synthesized. We then performed subgroup analysis. The non-metastatic and metastatic CRPC (nm/mCRPC) observations were analyzed separately. Data analyses were performed using R software (4.2.1) based on Bayesian framework. 6,993 subjects from seven eligible RCTs were analyzed. Enzalutamide, apalutamide and darolutamide were more effective than bicalutamide in treating CRPC, and the performance of darolutamide was slightly worse than the other two second-generation ARIs. Similar adverse events rate were observed among the second-generation ARIs and bicalutamide. Apalutamide showed a slightly higher rate of Grade 3+ AEs, percentages of AE-related drug withdrawals and AE-related mortality. Patients receiving enzalutamide had significantly higher rate of hypertension and fatigue. In subgroup analysis, enzalutamide showed better therapeutic effects compared with bicalutamide in both nmCRPC and mCRPC groups. In nmCRPC group, enzalutamide and apalutamide had more benefits on PFS and PSA-PFS compared with darolutamide. We displayed the probability ranking map of PFS, PSA-PFS, OS, time to cytotoxic chemotherapy, PSA response rate and relative AE outcomes. The current network meta-analysis indicated that the second-generation ARIs were superior to the conventional ARI, bicalutamide. The three second-generation ARIs showed incomplete equivalence on CRPC treatment. The darolutamide was slightly less effective compared with enzalutamide and apalutamide. The adverse events of apalutamide were worse than the others, but no statistical significance was observed among these vital AEs. All ARIs were generally well-tolerated. These results may provide reference to clinical decision and further direct comparison trials. https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022370842.

Lutetium-177-PSMA-617 radioligand therapy in patients with high volume metastatic prostate cancer prior to chemotherapy and new generation androgen deprivation therapy: Clinical Experience.

We aimed to evaluate the efficacy oflutetium-177-prostate-specific membrane antigen-617 (177Lu-PSMA-617) with the luteinizing hormone releasing hormone (LHRH) analogues in the first or in the second-line setting formetastatic castration sensitive patients and metastatic castration resistance after progression with LHRH analogues. Sixteen consecutive patients with high volume metastatic prostate cancer undergone 177Lu-PSMA-617 therapy who were refused chemotherapy and were unable to use new generation anti-androgen drugs because of unavailibility of reimbursement, were included in this retrospective study. Prostate specific antigen (PSA) response (>50% decrease), disease control rate (DCR: complete or partial response), progression-free survival (PFS) and overall survival (OS) were calculated to evaluate according to the clinicopathological features of the patients. Treatment response evaluated by 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT). Mean age was 74,6 (SD±8,36). Among them, 7 (43,8%) patients has castration resistant disease, while the remaining has castration sensitive disease. Lutetium-177-PSMA-617 was administered to 10 (62,5%) patients as one of the first-line treatment and 6 patients received the treatment after progression on LHRH as a second-line treatment. Considering all patients, PSA response rate and DCR were 50% and 62% respectively. The median PFS and OS (with 95% CI) were 11,2 months (11-15) and 29 months (25,6-32,4), respectively in patients treated with 177Lu-PSMA-617 and LHRH analogues. Clinicopathological features and basal PSA level did not have effect on PSA response rates, DCR, OS and PFS. On the other hand, increment in PFS and OS (with 95% CI) was observed in castration resistant disease and in the second-line therapy; for castration resistant disease 16,5 months (12.3-19.7); 30 months (25.3-32.7), for the second-line therapy 14.5 months (12-20.5); 29 months (NR), respectively but statistically not significant. Serious toxicity was observed in a limited number of patients (18,7%), treatment-related death was not observed. Favorable results can be achived with second-line 177Lu-PSMA-617 treatment in terms of OS and PFS, especially in castration-resistant disease, when chemotherapy and new generation ADT's cannot be used.