Prostate-specific Antigen Response Rate Research Articles

Heterogeneity of [68Ga]Ga-PSMA-11 PET/CT in metastatic castration-resistant prostate cancer: genomic characteristics and association with abiraterone response.

The aim of this study was to evaluate the impact of the spatial heterogeneity of prostate-specific membrane antigen (PSMA) uptake on circulating tumor DNA (ctDNA) characteristics and the response rate to new hormonal agent (NHA) treatment. This retrospective study included 153 patients with metastatic castration-resistant prostate cancer (mCRPC) who underwent gallium-68 [68Ga]Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) and ctDNA sequencing with a less than 2-week interval. SUVhetero was defined as the variance of SUVmean for each PSMA-positive lesion. SUVmax-mean was obtained by subtracting the SUVmax by the SUVmean. Patients receiving abiraterone treatment after [68Ga]Ga-PSMA-11 PET/CT and ctDNA sequencing and with complete follow-up record were included into prostate-specific antigen (PSA) response rate analysis. PSA response was defined as a reduction of greater than 50% from baseline. The ctDNA detection rate was 65% (100/153). Higher SUVhetero value contributed to higher ctDNA% (Spearman's rho = 0.278, p < 0.002). A total of 60 patients were included in PSA response rate analysis. The median follow-up was 19.3 (IQR 16.2-23.2) months. Compare to patients with higher SUVhetero value, patients with NA SUVhetero had a higher PSA response rate (52% vs. 90%, p = 0.036). A higher SUVmax-mean value was strongly correlated with higher SUVhetero (Spearman's rho = 0.833, p < 0.0001). Patients with higher SUVmax-mean value also had a higher PSA response rate compared to patients with lower SUVmax-mean value (83.3% vs. 53.3%, p = 0.024). An external cohort confirmed baseline SUVmax-mean value was associated with enzalutamide treatment response rate. Patients with alterations in AR, DNA damage repair pathway, TP53, AR-associated pathway, cell cycle pathway, or WNT pathway had higher SUVmax-mean value compared to those without (p < 0.05). Spatial heterogeneity of the PSMA uptake was associated with ctDNA characteristics and response rate to NHA treatment.

A Retrospective Study of the Effect of Metformin on Patients with Metastatic Prostate Cancer.

Previous studies demonstrated that metformin could lead to an inhibition of proliferation of cancer cells through a shift from anabolic to catabolic metabolism. In this study, we seek to investigate the effect of metformin in metastatic prostate cancer. Patients followed at Northwell Health Zuckerberg Cancer Center during 2014-2018 were included if they were diagnosed with metastatic hormone-sensitive prostate cancer (mHSPC) or metastatic castration-resistant prostate cancer (mCRPC), with ⩾6 months follow-up with and without metformin treatment. The primary outcomes, 6-month prostate-specific antigen (PSA) response, overall survival (OS), and radiographic progression free survival (rPFS), were evaluated. There were 267 patients included in the final analysis; 196 patients had mHSPC (73.2%) and 71 had mCRPC (26.8%). Within the mHSPC subjects, there was a significant difference in OS between metformin vs nonmetformin groups (148.5 vs 85.6 months; P < .046) in a univariate analysis; patients who took metformin had a significantly longer OS than subjects who did not (median OS: 148.5 vs 86 months; P < .046). There was no significant difference between the 2 groups with respect to either PSA response rate at 6 months or rPFS or OS in patients with mHSPC in both univariate and multivariate analysis. Within the mCRPC subjects, there was no significant difference between metformin and nonmetformin groups with respect to OS (43.3 vs 51.5 months; P < 0.160) or PSA response at 6 months (38.5% vs 57.1%; p < 0.24); however, patients on metformin had a significantly shorter rPFS in both the univariate analysis (7.3 vs 17.4; P < .0002) and in the multivariate analysis (HR = 2.52; 95% CI: 1.24m 5.11; P < .0109). Among patients with mHSPC, use of metformin was not significantly associated with improved OS in the multivariate analysis.

Randomised phase II trial of stereotactic body radiotherapy in combination with checkpoint inhibitors in metastatic castration-resistant prostate cancer (CheckPRO): a study protocol

IntroductionImmunotherapy with checkpoint inhibitors (CPIs) has revolutionised cancer treatment but has no convincing effect in metastatic castration-resistant prostate cancer (mCRPC). It has been suggested that a combination of CPI and...

The presence of lymph node metastases and time to castration resistance predict the therapeutic effect of enzalutamide for castration-resistant prostate cancer.

Enzalutamide is effective against castration-resistant prostate cancer (CRPC). However, it is unclear which patients would benefit more from enzalutamide treatment. Here, we analyzed patients who received enzalutamide as first-line therapy for CRPC and evaluated the factors that predict treatment response and prognosis. We retrospectively analyzed 101 patients treated with enzalutamide for CRPC at our institution. As primary endpoints we regarded the prostate-specific antigen (PSA) response rate and PSA-progression-free survival (PSA-PFS) from the start of enzalutamide treatment. Laboratory and imaging data were analyzed to predict treatment efficacy. PSA reductions of ≥ 50% and ≥ 90% were observed in 78 (77%) and 47 (47%) patients, respectively, compared with the baseline. During the follow-up period, 67 (66%) patients showed PSA progression, with a median PSA-PFS of 11months. Moreover, 31 patients (31%) died, with a median overall survival of 64months. On multivariate analysis, lymph node metastases at the start of enzalutamide treatment [odds ratio (OR) 0.0575, 95% confidence interval (CI) 0.0105-0.316, p = 0.0010] and time to CRPC (OR 0.177, 95% CI 0.0428-0.731, p = 0.0167] were associated with ≥ 90% PSA response. Lymph node metastases (hazard ratio [HR] 3.00, 95% CI 1.48-6.09, p = 0.0023) and time to CRPC (HR 1.84, 95% CI 1.02-3.30, p = 0.0419) were also predictors of PSA-PFS on a multivariate model. Time to CRPC and lymph node metastasis were predictors of the PSA response rate and PSA-PFS.

Efficacy and Safety of Brazilian Green Propolis in Biochemically Recurrent Prostate Cancer after Radical Prostatectomy: A Single-Arm Phase II Study

Background: Radiation or hormonal therapy is considered for prostate cancer patients with biochemical recurrence (BCR) after radical prostatectomy (RP). However, these therapies have their own complications. To delay the start of these therapies, we investigated the efficacy and safety of Brazilian green propolis for the treatment for BCR after RP. Materials and Methods: This single-center, single-arm open trial included 22 patients who experienced BCR after RP between 2016 and 2019. The patients received nine softgels of Brazilian green propolis (containing 40 mg propolis per capsule) daily for 6 months. The primary outcome was the prostate-specific antigen (PSA) response rate. The secondary outcomes included progression-free time, PSA slope (1/PSA doubling time) response rate, quality of life, and safety profile. Results: The PSA response rate was 0%. The mean PSA slopes before and after baseline were 0.12 month−1 and 0.08 month−1, respectively. Fifteen patients (68%) showed a decreased PSA slope after treatment. There were no negative effects on quality of life or serious adverse events leading to treatment discontinuation. Conclusion: There was no significant anticancer response in patients who received Brazilian green propolis. However, the PSA slope was decreased after propolis administration. Further, Brazilian green propolis may be safely consumed by patients.

Efficacy of cabazitaxel and androgen splicing variant-7 status in circulating tumor cells in Asian patients with metastatic castration-resistant prostate cancer

Androgen receptor splice variant-7 (AR-V7) expression in circulating tumor cells (CTCs) in metastatic castration-resistant prostate cancer (mCRPC) is associated with abiraterone and enzalutamide resistance. We determine whether cabazitaxel (CBZ) is equally effective in AR-V7-positive and -negative CRPC and whether AR-V7-positive patients retain CBZ sensitivity. This is the first prospective, open-label, Asian validation study of CBZ in Japanese patients with mCRPC after docetaxel (n = 48; four CBZ cycles; 2017–2020, Juntendo University Hospitals). Primary endpoint was prostate-specific antigen response rate (PSA-RR); secondary endpoints included overall survival (OS), bone scan index (BSI) PSA-RR (≥ 50% decline from baseline) for CTC−/ARV7−, CTC+ /ARV7−, and CTC +/ARV7+ groups. PSA-RR ≥ − 30% was 38% (18/48) and ≥ − 50% was 26% (12/48). BSI-change rate ≥ − 30% was 19% (9/41) and ≥ − 50% was 17% (8/41). Median OS was 13.7(12.2–18.9) months. PSA decline in early CBZ treatment associated with OS (p = 0.00173). BSI decline associated with OS (p = 0.0194). PSA-RR(≥ 50%) was 43%(6/14) in CTC−/ARV7−, 19%(5/26) in CTC+ ARV7−, and 12%(1/8) in CTC+/ARV7+ ( p > 0.05). AR-V7 in CTCs at baseline not associated with OS. AR-V7 was not associated with CBZ resistance in CTCs. Reductions in BSI and PSA in early stages of CBZ treatment may predict OS.

Efficacy of Novel Hormone Agents in the Treatment of Metastatic Castration-resistant Prostate Cancer: A Real-world Retrospective Study.

Novel hormone agents (NHA) have become important tools for the treatment of advanced prostate cancer. Among them, abiraterone and enzalutamide are two major regimens in the treatment of metastatic castration-resistant prostate cancer (MCRPC). The aim of this study was to evaluate the efficacy of both drugs in patients who had disease progression after androgen deprivation therapy (ADT), using our real-world database. We retrospectively analyzed MCRPC patients who received abiraterone and enzalutamide between October 2010 and October 2021. The associations between baseline demographics and clinical outcomes were evaluated. ADT was defined as luteinizing hormone-releasing hormone (LHRH) agonists, antagonists, or orchiectomy. Of the 324 included patients, the median age was 77 years. Amongst them, 81 patients received chemotherapy-naïve abiraterone, 141 received post-chemotherapy abiraterone, 64 patients received chemotherapy-naïve enzalutamide and 38 patients received post-chemotherapy enzalutamide. The median overall survival was 43.6 months among all NHA-treated MCRPC patients. Pre-MCRPC ADT duration >25.31 months and enzalutamide use were each associated with a decreased risk of death (HR=0.54, 95% CI=0.39-0.75, p<0.001, and HR=0.53, 95% CI=0.33-0.87, p=0.012, respectively), while high-volume disease was associated with an increased risk of death (HR=1.53, 95% CI=1.10-2.21, p=0.007). Upfront chemotherapy and pre-MCRPC ADT duration of >21.03 months were each associated with an increased prostate-specific antigen (PSA) response after NHA treatment (OR=3.18, 95% CI=1.33-7.63, p=0.010, and OR=2.72, 95% CI=1.63-4.54, p<0.001, respectively). Our real-world data revealed the effectiveness of using both abiraterone and enzalutamide in the treatment of MCRPC patients. Long pre-MCRPC ADT duration and enzalutamide use were both associated with a decreased risk of death regardless of four different treatment sequences. Upfront docetaxel and longer pre-MCRPC ADT duration were each associated with an increased NHA PSA response rate.

Glucocorticoid receptor and androgen receptor-targeting therapy in patients with castration-resistant prostate cancer.

ObjectiveThe glucocorticoid receptor (GR) promotes resistance to androgen receptor (AR)-targeting therapies in castration-resistant prostate cancer (CRPC) by bypassing AR blockade. However, the clinical relevance of evaluating GR expression in patients with CRPC has not been determined. The present study investigated the association of relative GR expression in CRPC tissue samples with treatment response to AR-targeting therapy.MethodsLevels of GR, AR-FL, and AR-V7 mRNAs were measured in prostate cancer tissue from prospectively enrolled CRPC patients who were starting treatment. Patients were divided into groups with high and low AR-V7/AR-FL ratios and with high and low GR/AR-FL ratios. The primary endpoint was prostate-specific antigen (PSA) response rate to treatment.ResultsEvaluation of 38 patients treated with AR-targeting therapies showed that the PSA response rate was significantly higher in patients with low than high AR-V7/AR-FL ratios (77.8% vs. 25.0%, p=0.003) and in patients with low than high GR/AR-FL ratios (81.3% vs. 27.3%, p=0.003). Patients with low GR/AR-FL ratios had higher rates of PSA progression-free survival (46.0% vs. 22.4%, p=0.006), radiologic progression-free survival (28.9% vs. 10.0%, p=0.02), and overall survival (75.2% vs. 48.0%, p=0.037) than patients with high GR/AR-FL ratios. The association of GR/AR-FL ratio with PSA response to AR-targeting therapy remained significant in multivariable models. Evaluation of the 14 patients who received taxane chemotherapy showed that PSA response rates did not differ significantly in those with low and high AR-V7/AR-FL and GR/AR-FL ratios, although no definitive conclusions can be drawn due to the small number of patients.ConclusionRelative GR expression is associated with sensitivity to AR-targeting therapy and survival in patients with CRPC. Large-scale prospective validation and liquid biopsy-based studies are warranted.

177Lu-PSMA-I&T for Treatment of Metastatic Castration-Resistant Prostate Cancer: Prognostic Value of Scintigraphic and Clinical Biomarkers.

The aim of this retrospective analysis was to determine prostate-specific antigen (PSA) response, PSA progression-free survival (PFS), and overall survival (OS) in a large cohort of patients with metastatic castration-resistant prostate cancer (mCRPC) treated with 177Lu-PSMA-I&T and to identify clinical and scintigraphic prognostic factors for outcome. Methods: In total, 301 consecutive mCRPC patients were included in this analysis. Prognostic factors included clinical parameters, routine laboratory parameters, and findings on posttreatment scintigraphy. Scintigraphic tumor uptake of 177Lu-PSMA-I&T was compared with salivary gland uptake and classified as high or low. The longest extent of skeletal metastatic disease was measured, and its changes during therapy were used to define scintigraphic progression, response, and stable disease. A PSA response of at least 50%, PSA PFS, and OS were calculated. Results: In total, 1,138 cycles (median, 3 cycles per patient) of 177Lu-PSMA-I&T using a standard activity of 7.4 GBq were applied intravenously every 4-10 wk (median, 6 wk). Overall, 34% (95% CI, 28%-38%) of patients showed a PSA response of at least 50%, and the median PSA PFS and OS of the total patient cohort were 16.0 wk (95% CI, 12.1-19.9) and 13.8 mo (95% CI, 12.4-15.5), respectively. Patients with high scintigraphic tumor uptake showed a higher PSA response rate of at least 50% (45.7% vs. 10.4%; P < 0.0001) and a significantly reduced risk of PSA progression (median event time, 24.9 vs. 9.0 wk; hazard ratio, 0.3; 95% CI, 0.2-0.5; P < 0.0001). In our data, risk of death was not significantly different between patients with high scintigraphic uptake and those with low scintigraphic uptake (median, 14.4 vs. 12.4 mo; hazard ratio, 0.9; 95% CI, 0.6-1.3; P = 0.6). In a multivariable analysis, the following pretherapeutic prognostic factors for OS were identified: alkaline phosphatase, lactate dehydrogenase, and PSA levels; prior chemotherapy; and the presence of visceral metastases. Scintigraphic response was a strong prognostic factor for PSA response, PSA PFS, and OS after 1 treatment cycle. Conclusion: This retrospective analysis of a large group of consecutive patients corroborates previous clinical experience for 177Lu-PSMA-I&T in mCRPC and establishes previously proposed prognostic factors. The skeletal tumor extent and its changes were identified as new potential biomarkers to predict the outcome of therapy after the first treatment cycle.

Enzalutamide in patients with non-metastatic castration-resistant prostate cancer after combined androgen blockade for recurrence following radical treatment in Japan (Japanese research for patients with non-metastatic castration-resistant prostate cancer-enzalutamide: JCASTRE-zero)—a prospective single-arm interventional study

BackgroundThe effect of enzalutamide in patients with non-metastatic castration-resistant prostate cancer after combined androgen blockade, which represents a patient profile similar to real-world clinical practice in Japan, remains unknown. Therefore, we investigate the efficacy and safety of enzalutamide after combined androgen blockade for recurrence following radical treatment in Japanese patients with non-metastatic castration-resistant prostate cancer.MethodsWe analyzed 66 patients with non-metastatic castration-resistant prostate cancer after combined androgen blockade for recurrence following radical prostatectomy or radiation therapy who were prospectively enrolled from October 2015 to March 2018. They received enzalutamide 160 mg orally once daily until the protocol treatment discontinuation criteria were met. The primary endpoint was prostate-specific antigen-progression-free survival, defined as the time from enrollment to prostate-specific antigen-based progression or death from any cause. The secondary endpoints included overall survival, progression-free survival, metastasis-free survival, time to prostate-specific antigen progression, prostate-specific antigen response rate, chemotherapy-free survival, and safety assessment.ResultsThe median observation period was 27.3 months. The median prostate-specific antigen-progression-free survival was 35.0 months (95% confidence interval, 17.5 to not reached). The median overall survival, median progression-free survival, median metastasis-free survival, and chemotherapy-free survival were not reached, with the corresponding 2-year rates being 91.6%, 67.1%, 72.4%, and 85.8%, respectively. The 50% prostate-specific antigen response rate was 88.9%, with the median time being 2.8 months. In total, 42.2% of the patients experienced adverse events, with malaise being the most common.ConclusionsEnzalutamide effectively manages non-metastatic castration-resistant prostate cancer after combined androgen blockade for recurrence following radical treatment.Trialregistration: UMIN000018964, CRB6180007.

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

BackgroundPembrolizumab and olaparib have shown single-agent activity in patients with previously treated metastatic castration-resistant prostate cancer (mCRPC). ObjectiveTo evaluate the efficacy and safety of pembrolizumab plus olaparib in mCRPC. Design, setting, and participantsCohort 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. InterventionPembrolizumab 200 mg intravenously every 3 wk plus olaparib 400-mg capsule or 300-mg tablet orally twice daily. Outcome measurements and statistical analysisThe 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 limitationsOf 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. ConclusionsPembrolizumab 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 summaryPembrolizumab plus olaparib showed antitumor activity and expected safety in patients with metastatic castration-resistant prostate cancer.

The efficacy and safety of immune checkpoint inhibitors in metastatic castration-resistant prostate cancer: A systematic review and meta-analysis.

Background:We aim to assess the efficacy and safety profiles of immune checkpoint inhibitors in patients with metastatic castration-resistant prostate cancer using a meta-analysis.Methods:We extracted and examined data from phase I, II and III clinical trials from PubMed, Embase, Web of Science, and Cochrane Library, which included patients with metastatic castration-resistant prostate cancer who were treated with immune checkpoint inhibitors. We performed a meta-analysis to investigate several indexes of efficacy and safety, including the objective response rate, 1-year overall survival (OS) rate, prostate-specific antigen response rate, and adverse event rate of immune checkpoint inhibitors. The material data were calculated and pooled using The R Project for Statistical Computing and STATA 12.0 software.Results:We identified 12 clinical trials in our study. We assessed the pooled frequencies of all-grade AEs and grade ≥ 3 AEs first and showed 0.82 (95% CI: 0.74–0.91, I2 = 94%, P < .01) and 0.42 (95% CI: 0.33–0.54, I2 = 96%, P < .01), respectively. The objective response rate was 0.10 (95% CI: 0.04–0.19, I2 = 70%, P < .01), and the 1-year OS and prostate-specific antigen response rate were 0.55 (95% CI: 0.45–0.67, I2 = 93%, P < .01) and 0.18 (95% CI: 0.16–0.20, I2 = 43%, P = .03), respectively.Conclusion:The immune checkpoint inhibitors therapy was well tolerated and showed potential to improve tumor responses in patients with metastatic castration-resistant prostate cancer.

Nivolumab plus rucaparib for metastatic castration-resistant prostate cancer: results from the phase 2 CheckMate 9KD trial

BackgroundCheckMate 9KD (NCT03338790) is a non-randomized, multicohort, phase 2 trial of nivolumab plus other anticancer treatments for metastatic castration-resistant prostate cancer (mCRPC). We report results from cohorts A1 and A2...

A narrative review of the role of glucocorticoid receptors in prostate cancer: developments in last 5 years.

Background and ObjectiveGlucocorticoids, secreted from the adrenal gland, are commonly used in the treatment of castration-resistant prostate cancer (CRPC) because of their anti-inflammatory and anti-toxic effects. However, glucocorticoids have been reported to have the opposite effects within the course of treatment. Many studies have shown that glucocorticoid receptors (GRs) are involved in the establishment of a dominant population of androgen-independent malignant cells, which may result in CRPC. In this review, we summarized the mechanisms of GRs in CRPC and the clinical application of glucocorticoids based on the present evidence.MethodsWe summarized the isoforms of GRs and the mechanisms involved in CRPC. An updated literature search was performed from the ClinicalTrials database, the National Center for Biotechnology Information database and European Union Drug Regulating Authorities Clinical Trials database. The focus was on the timeframe from 2017 to 2022. At least one primary or secondary outcome [prostate-specific antigen (PSA) response rate, progression-free survival (PFS) or overall survival (OS) and median time to PSA progression] according to studies should be included.Key Content and FindingsThe molecular structures and applications of the isoforms of GR have been intensively researched in the past 60 years. In recent years, researchers have pointed out that GRs may be involved in the development of CRPC via genomic and non-genomic effects. Clinical trials in the past 5 years have focused on the efficacy of drugs regarding CRPC. The use of glucocorticoids during treatments of CRPC follows the guidelines (e.g., NCCN Guidelines®, guidelines of CSCO, etc.). Based on the collected data, prednisone appears to be the most widely used steroid hormone, followed by dexamethasone. Comparisons of the PSA response rate and the median time to PSA progression revealed that the efficacy of the 2 hormones is similar; however, further research on the effect of steroid hormone in CRPC is still required.ConclusionsVarious GR isoforms may play an important part in the development of CRPC, whose mechanism remains unclear. Most clinical trials have focused on the use of prednisone in the last 5 years. The efficacy of prednisone and dexamethasone is similar.

Multisite Radiotherapy Combined With Tislelizumab for Metastatic Castration-Resistant Prostate Cancer With Second-Line and Above Therapy Failure: Study Protocol for an Open-Label, Single-Arm, Phase Ib/II Study.

BackgroundTislelizumab combined with radiotherapy as a salvage treatment for patients with end-stage metastatic castration-resistant prostate cancer (mCRPC) is not reported. This study aimed to describe a protocol to evaluate the safety and efficacy of multisite radiotherapy combined with tislelizumab as a salvage therapy for mCRPC in patients who had at least one second-line treatment failure.MethodsThe study included patients with mCRPC who had at least one lesion suitable for radiotherapy and failed androgen deprivation therapy (ADT), followed by at least one novel second-line endocrine therapy. All patients received tislelizumab monotherapy induction therapy for two cycles, then combined with multisite radiotherapy for one cycle, followed by tislelizumab maintenance therapy, until either disease progressed or the patient developed unacceptable toxicity. Radiation methods and lesions were individually selected according to the specified protocol. Primary endpoints included safety and objective response rate. Secondary endpoints included prostate-specific antigen (PSA) response rate, disease control rate, overall survival, radiographic progression-free survival (rPFS), and biochemical progression-free survival (bPFS). Furthermore, the exploratory endpoints included the identification of the predictive biomarkers and exploration of the correlation between biomarkers and the tumor response to the combined regimen.DiscussionThis study included three treatment stages to evaluate the efficacy of immunotherapy and the combination of immunotherapy and radiotherapy for patients with mCRPC who have had at least second-line treatment failure. Additionally, radiation-related and immune-related early and late toxicities were determined, respectively. Furthermore, the study also aimed to identify the predictive biomarkers associated with immunotherapy for treating mCRPC.Trial Registration https://www.chictr.org.cn/showproj.aspx?proj=126359, identifier ChiCTR2100046212.

Abstract 532: Circulating tumor DNA and outcomes with lutetium-PSMA in advanced prostate cancer: Preliminary results from an Australian study

Abstract Recent clinical trials have revealed that Lutetium PSMA-617 (Lu-PSMA, a small molecular inhibitor of prostate-specific membrane antigen radiolabelled with the beta emitter 177-Lutetium) significantly improves clinical outcomes including overall survival for patients with metastatic castration resistant prostate cancer (mCRPC). Nevertheless, owing to the highly heterogeneous nature of mCRPC, responses to Lu-PSMA therapy can be variable, with resistance inevitable. Currently, there are no existing data on the genomic landscape of mCRPC in the context of this therapy, with the identification of biomarkers linked to outcomes with Lu-PSMA being a critical unmet need in order to select patients most likely to benefit from treatment and to dissect mechanisms of resistance. mCRPC patients with high PSMA expression on positron emission tomography scans and prior treatment with docetaxel chemotherapy and an androgen receptor pathway inhibitor were enrolled on a compassionate access prospective registry at Peter MacCallum Cancer Centre. Patients received Lu-PSMA every 6 weeks for 4-6 cycles and entered into follow-up. Peripheral blood samples were collected for plasma circulating tumour DNA (ctDNA) analysis at baseline and prior to cycle 2 of therapy. A highly-sensitive targeted next-generation sequencing assay was applied to patient plasma and matched leukocytes. Somatic mutations (single nucleotide variants/indels) and copy number alterations from 43 genes were reported, along with the estimated ctDNA fraction. Current patient numbers preclude formal statistical analysis of genomic aberrations, however dynamic changes in ctDNA were assessed in relation to prostate-specific antigen (PSA) response and clinical and/or radiographic progression. In total, 19 plasma samples were analysed from 13 mCRPC patients with a median age of 71. Patients had between one and four prior lines of therapy for mCRPC and had a median time on Lu-PSMA therapy of 3.7 months. ctDNA was detected in 17/19 plasma samples with a median fraction of 26% (range 0-89%). Overall, a PSA response rate of 54% was observed. Interestingly, patients with higher baseline ctDNA fractions were more likely to experience a PSA response to Lu-PSMA therapy (median ctDNA fraction of responders 49% vs 10% in non-responders, p=0.1). Additionally, no PSA responses were seen in patients who did not attain a reduction in plasma ctDNA from baseline to cycle 2. This is the first targeted assessment of serial plasma samples from patients receiving Lu-PSMA therapy. Using a highly sensitive liquid biopsy assay, ctDNA was detectable in almost all samples. In this preliminary analysis, both baseline ctDNA fraction and early dynamic changes in ctDNA fraction appear to have clinical importance in Lu-PSMA therapy. Recruitment to this registry is proceeding rapidly, with further data available by April 2022. Citation Format: Heidi Fettke, Nicole Ng, Christine Hauser, Patricia Bukczynska, Elizabeth Medhurst, Louise Kostos, James Buteau, Jason Steen, Tu Nguyen-Dumont, Michael Hofman, Arun A. Azad. Circulating tumor DNA and outcomes with lutetium-PSMA in advanced prostate cancer: Preliminary results from an Australian study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 532.

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

TPS5104 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 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 pharmacokinetics (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, 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 10 Feb 2022, 4 sites have been initiated and 23 patients enrolled; currently, dose escalation is ongoing. Clinical trial information: NCT04644770.

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

TPS5111 Background: Darolutamide is a structurally distinct and highly potent androgen receptor inhibitor (ARI) that significantly improved metastasis-free survival by ̃2 years and reduced the risk of death by 31% vs placebo in patients with nonmetastatic castration-resistant prostate cancer (CRPC). Darolutamide has a favorable safety and tolerability profile, with only ≤2% difference vs placebo for most adverse events (AEs) of interest (falls, fractures, hypertension, mental impairment). Fatigue was the only AE with &gt; 10% incidence in the darolutamide arm (13.2%; placebo, 8.3%). Darolutamide has shown lower blood–brain barrier penetration than other ARIs in preclinical models (supported by human neuroimaging studies), which may lead to a lower risk of central nervous system-related AEs and has a low potential for drug–drug interactions. For patients with metastatic hormone-sensitive prostate cancer (mHSPC), the combination of darolutamide and ADT is expected to offer a favorable benefit–risk profile. ARASEC will evaluate the efficacy and safety of darolutamide plus ADT in mHSPC in the US (NCT05059236) and complement the data in the ongoing ARANOTE study (NCT04736199). Methods: ARASEC is a US-based, phase 2, open-label, single-arm study with an external control arm. Eligible patients will have confirmed adenocarcinoma of the prostate, radiologic evidence of metastatic disease by conventional imaging, and Eastern Cooperative Oncology Group performance status (ECOG PS) ≤2. Patients with mHSPC will receive darolutamide 600 mg twice daily plus ADT (luteinizing hormone-releasing hormone agonist/antagonist or orchiectomy). The control arm for ARASEC will be derived from the 393 patients with mHSPC treated with ADT alone in the CHAARTED trial. Patients in the active arm will be matched 1:1 to patients in the control arm using important baseline characteristics such as age, ECOG PS, extent of disease defined as low or high volume according to CHAARTED, and presence of bone and visceral metastases. Study duration was defined as the time from the first patient’s first visit until either the event count threshold triggering the primary endpoint analysis has been met or all patients have been followed for ≥2 years after enrollment, whichever occurs later. The primary endpoint is progression-free survival (PFS), defined in CHAARTED as the time from enrollment to prostate-specific antigen (PSA) progression, clinical progression (including radiological or symptomatic progression or clinical deterioration), or death, whichever occurs first. Secondary endpoints are overall survival, radiographic PFS, time to CRPC, complete PSA response rate at 6 months, and safety. Patient recruitment is in progress. Clinical trial information: NCT05059236.

Olaparib for Chinese metastatic castration-resistant prostate cancer: A real-world study of efficacy and gene predictive analysis.

To evaluate the real-world effectiveness and gene predictive analysis of olaparib in Chinese patients with metastatic castration-resistant prostate cancer (mCRPC), amulticenter, retrospective, real-world study was conducted by involving Chinese patients with mCRPC from December 2017 to June 2021. Homologous Recombination repair (HRR)gene mutation (HRRm) status was identified using targeted next-generation sequencing (NGS). The primary endpoint includes prostate-specific antigen (PSA) response rate (PSA50). Secondary end points include PSA progression-free survival (PSA-PFS), exploratory endpoints include PSA50, and PSA-PFS in HRRm-negative patients with variants of unknown significance (VUS). Survival rates were analyzed using Kaplan-Meier (KM) plot. A total of 39 eligible patients with a median age of 65 (interquartile range [IQR]: 59.5-69.5) years were included in the study. Overall, 40% (12/30) of the patients with mCRPC achieved PSA50 and the median PSA-PFS was 3.1months (95% Confidence interval [CI]: 2.4-7). Furthermore, higher PSA50 rate and longer PSA-PFS were observed in HRRm-positive patients (PSA50: 50% [7/14]; median PSA-PFS: 5.3months, 95% CI: 3.73-10). Among the HRRm-positive patients, those harboring the BRCA2 aberrations experienced best clinical efficacy (PSA50: 55.5% [5/9] and median PSA-PFS [95% CI]: 9.5months [4.3, NA]). Clinical benefit was also observed in HRRm-negative patients (PSA50: 31.3% [5/16]; median PSA-PFS [95% CI]:2.05months [1.5,8]), wherein most patients with a PSA50 response were carrying VUS (PSA50: 50% [4/8]; median PSA-PFS [95% CI]: 2.75months [1.27, NA]). In one patients with mutation in the ATR gene, the PSA level decreased by 62%. Olaparib improved PSA response and prolonged PSA-PFS in Chinese mCRPC patients especially in those carrying HRR mutation. Among the HRR genes, patients with BRCA2 mutation showed the best clinical benefit. Besides, some patients carrying VUS on HRR gene and other DNA damage response (DDR) gene mutations also showed response to olaparib treatment, indicating that the clinical benefits observed in HRR-negative group were driven by VUS and other DDR gene mutation. However, this should be further explored in the future, and more molecular functional studies are needed to reclassify VUS for better clinical treatment decision-making and management of mCRPC.

Enzalutamide Versus Abiraterone plus Prednisolone Before Chemotherapy for Castration-resistant Prostate Cancer: A Multicenter Randomized Controlled Trial

BackgroundEnzalutamide (ENZ) and abiraterone plus prednisolone (ABI) improve survival in castration-resistant prostate cancer (CRPC). However, which agent is better for patients with CRPC remains unclear. ObjectiveTo evaluate whether ENZ or ABI is better as first-line treatment for CRPC. Design, setting, and participantsAn investigator-initiated, multicenter, randomized controlled trial was conducted in Japan. The study enrolled 203 patients with CRPC before chemotherapy between February 20, 2015, and July 31, 2019. Patients were randomly assigned 1:1 to the ENZ or ABI arm. Outcome measurements and statistical analysisThe primary endpoint was time to prostate-specific antigen (PSA) progression. Secondary endpoints included the PSA response rate (≥50% decline from baseline), overall survival, and safety. A log-rank test was used for comparison of survival analyses between arms. Results and limitationsAfter randomization, 92 patients in each arm were treated and analyzed. Time to PSA progression did not significantly differ between the arms (median 21.2 mo for ENZ and 11.9 mo for ABI; hazard ratio [HR] 0.81, 95% confidence interval [CI] 0.51–1.27; p = 0.1732). There was a significant difference in the PSA response rate between the arms (72% for ENZ and 57% for ABI; p = 0.0425). There was no significant difference in overall survival (median 32.9 mo for ENZA and 35.5 mo for ABI; HR 1.17, 95% CI 0.72–1.88; p = 0.5290). Grade ≥3 adverse events were observed in 11% of patients in the ENZA arm and 21% in the ABI arm (p = 0.1044). ConclusionsENZ did not show any survival benefit in comparison to ABI, but showed a better PSA response rate with a low rate of severe adverse events in CRPC. Patient summaryResults from our study suggest that use of enzalutamide before abiraterone may have potential clinical benefits for patients with castration-resistant prostate cancer.