Bipolar androgen therapy plus nivolumab for patients with metastatic castration-resistant prostate cancer: the COMBAT phase II trial.

Cyclic high-dose testosterone administration, known as bipolar androgen therapy (BAT), is a treatment strategy for patients with metastatic castration-resistant prostate cancer (mCRPC). Here, we report the results of a multicenter, single arm Phase 2 study (NCT03554317) enrolling 45 patients with heavily pretreated mCRPC who received BAT (testosterone cypionate, 400 mg intramuscularly every 28 days) with the addition of nivolumab (480 mg intravenously every 28 days) following three cycles of BAT monotherapy. The primary endpoint of a confirmed PSA50 response rate was met and estimated at 40% (N = 18/45, 95% CI: 25.7-55.7%, P = 0.02 one-sided against the 25% null hypothesis). Sixteen of the PSA50 responses were achieved before the addition of nivolumab. Secondary endpoints included objective response rate (ORR), median PSA progression-free survival, radiographic progression-free survival (rPFS), overall survival (OS), and safety/tolerability. The ORR was 24% (N = 10/42). Three of the objective responses occurred following the addition of nivolumab. After a median follow-up of 17.9 months, the median rPFS was 5.6 (95% CI: 5.4-6.8) months, and median OS was 24.4 (95% CI: 17.6-31.1) months. BAT/nivolumab was well tolerated, resulting in only five (11%) drug related, grade-3 adverse events. In a predefined exploratory analysis, clinical response rates correlated with increased baseline levels of intratumoral PD-1 + T cells. In paired metastatic tumor biopsies, BAT induced pro-inflammatory gene expression changes that were restricted to patients achieving a clinical response. These data suggest that BAT may augment antitumor immune responses that are further potentiated by immune checkpoint blockade.

Test-retest repeatability of organ uptake on PSMA-targeted 18 F-DCFPyL PET/CT in patients with prostate cancer.

OBJECTIVES: We evaluated 18 F-DCFPyL test-retest repeatability of uptake in normal organs. METHODS: Twenty-two prostate cancer (PC) patients underwent two 18 F-DCFPyL PET scans within 7 days within a prospective clinical trial (NCT03793543). In both PET scans, uptake in normal organs (kidneys, spleen, liver, and salivary and lacrimal glands) was quantified. Repeatability was determined by using within-subject coefficient of variation (wCOV), with lower values indicating improved repeatability. RESULTS: For SUVmean , repeatability was high for kidneys, spleen, liver, and parotid glands (wCOV, range: 9.0%-14.3%) and lower for lacrimal (23.9%) and submandibular glands (12.4%). For SUVmax , however, the lacrimal (14.4%) and submandibular glands (6.9%) achieved higher repeatability, while for large organs (kidneys, liver, spleen, and parotid glands), repeatability was low (range: 14.1%-45.2%). CONCLUSION: We found acceptable repeatability of uptake on 18 F-DCFPyL PET for normal organs, in particular for SUVmean in the liver or parotid glands. This may have implications for both PSMA-targeted imaging and treatment, as patient selection for radioligand therapy and standardized frameworks for scan interpretation (PROMISE, E-PSMA) rely on uptake in those reference organs.

Multi-timepoint imaging with PSMA-targeted [18F]F-Florastamin PET/CT: lesion detection and comparison to conventional imaging.

OBJECTIVE: The aims of this study were to investigate the utility of [18F]F-Florastamin, a novel prostate-specific membrane antigen (PSMA)-targeted PET radiotracer with facile radiochemistry, relative to the conventional imaging for the detection of sties of disease and evaluate the effect of multi-timepoint imaging with [18F]F-Florastamin PET on lesion detectability. METHODS: Eight prostate cancer patients with known or suspected recurrence who underwent [18F]F-Florastamin PET/CT at 1-h and 2-h imaging time-points were included in this prospective pilot study. [18F]F-Florastamin PET images were interpreted visually and quantitatively at both time points and compared with CIM. RESULTS: [18F]F-Florastamin PET was superior to CT in the detection of active osseous metastases and small-sized metastatic lymph nodes that do not fall under the anatomic imaging size criteria for metastasis. Multi-timepoint imaging showed a significant reduction in the blood pool, bone marrow and muscular uptake, and increase in liver uptake over time. There is a significant improvement in tumor-to-background ratio (TBR) at the 2-h imaging time-point (P = 0.04). The mean percentage change in TBR at 2-h was 21% (SD = 0.31). CONCLUSIONS: [18F]F-Florastamin is a promising new radioligand for PSMA-targeted PET with suitable lesion detectability and high TBR at both time points.

Lack of repeatability of radiomic features derived from PET scans: Results from a 18 F-DCFPyL test-retest cohort.

OBJECTIVES: PET-based radiomic metrics are increasingly utilized as predictive image biomarkers. However, the repeatability of radiomic features on PET has not been assessed in a test-retest setting. The prostate-specific membrane antigen-targeted compound 18 F-DCFPyL is a high-affinity, high-contrast PET agent that we utilized in a test-retest cohort of men with metastatic prostate cancer (PC). METHODS: Data of 21 patients enrolled in a prospective clinical trial with histologically proven PC underwent two 18 F-DCFPyL PET scans within 7 days, using identical acquisition and reconstruction parameters. Sites of disease were segmented and a set of 29 different radiomic parameters were assessed on both scans. We determined repeatability of quantification by using Pearson's correlations, within-subject coefficient of variation (wCOV), and Bland-Altman analysis. RESULTS: In total, 230 lesions (177 bone, 38 lymph nodes, 15 others) were assessed on both scans. For all investigated radiomic features, a broad range of inter-scan correlation was found (r, 0.07-0.95), with acceptable reproducibility for entropy and homogeneity (wCOV, 16.0% and 12.7%, respectively). On Bland-Altman analysis, no systematic increase or decrease between the scans was observed for either parameter (±1.96 SD: 1.07/-1.30, 0.23/-0.18, respectively). The remaining 27 tested radiomic metrics, however, achieved unacceptable high wCOV (≥21.7%). CONCLUSION: Many common radiomic features derived from a test-retest PET study had poor repeatability. Only Entropy and homogeneity achieved good repeatability, supporting the notion that those image biomarkers may be incorporated in future clinical trials. Those radiomic features based on high frequency aspects of images appear to lack the repeatability on PET to justify further study.

A Phase Ib/II Study of Sabizabulin, a Novel Oral Cytoskeleton Disruptor, in Men with Metastatic Castration-resistant Prostate Cancer with Progression on an Androgen Receptor-targeting Agent.

PURPOSE: Sabizabulin, an oral cytoskeleton disruptor, was tested in a phase Ib/II clinical study in men with metastatic castration-resistant prostate cancer (mCRPC). PATIENTS AND METHODS: The phase Ib portion utilized a 3+3 design with escalating daily oral doses of 4.5-81 mg and increasing schedule in 39 patients with mCRPC treated with one or more androgen receptor-targeting agents. Prior taxane chemotherapy was allowed. The phase II portion tested a daily dose of 63 mg in 41 patients with no prior chemotherapy. Efficacy was assessed using PCWG3 and RECIST 1.1 criteria. RESULTS: The MTD was not defined in the phase Ib and the recommended phase II dose was set at 63 mg/day. The most common adverse events (>10% frequency) at the 63 mg oral daily dosing (combined phase Ib/II data) were predominantly grade 1-2 events. Grade ≥3 events included diarrhea (7.4%), fatigue (5.6%), and alanine aminotransferase/aspartate aminotransferase elevations (5.6% and 3.7%, respectively). Neurotoxicity and neutropenia were not observed. Preliminary efficacy data in patients treated with ≥1 continuous cycle of 63 mg or higher included objective response rate in 6 of 29 (20.7%) patients with measurable disease (1 complete, 5 partial) and 14 of 48 (29.2%) patients had PSA declines. The Kaplan-Meier median radiographic progression-free survival was estimated to be 11.4 months (n = 55). Durable responses lasting >2.75 years were observed. CONCLUSIONS: This clinical trial demonstrated that chronic oral daily dosing of sabizabulin has a favorable safety profile with preliminary antitumor activity. These data support the ongoing phase III VERACITY trial of sabizabulin in men with mCRPC.

High SUVs Have More Robust Repeatability in Patients with Metastatic Prostate Cancer: Results from a Prospective Test-Retest Cohort Imaged with 18F-DCFPyL.

Objectives: In patients with prostate cancer (PC) receiving prostate-specific membrane antigen- (PSMA-) targeted radioligand therapy (RLT), higher baseline standardized uptake values (SUVs) are linked to improved outcome. Thus, readers deciding on RLT must have certainty on the repeatability of PSMA uptake metrics. As such, we aimed to evaluate the test-retest repeatability of lesion uptake in a large cohort of patients imaged with 18F-DCFPyL. Methods: In this prospective, IRB-approved trial (NCT03793543), 21 patients with history of histologically proven PC underwent two 18F-DCFPyL PET/CTs within 7 days (mean 3.7, range 1 to 7 days). Lesions in the bone, lymph nodes (LN), and other organs were manually segmented on both scans, and uptake parameters were assessed (maximum (SUVmax) and mean (SUVmean) SUVs), PSMA-tumor volume (PSMA-TV), and total lesion PSMA (TL-PSMA, defined as PSMA - TV × SUVmean)). Repeatability was determined using Pearson's correlations, within-subject coefficient of variation (wCOV), and Bland-Altman analysis. Results: In total, 230 pairs of lesions (177 bone, 38 LN, and 15 other) were delineated, demonstrating a wide range of SUVmax (1.5-80.5) and SUVmean (1.4-24.8). Including all sites of suspected disease, SUVs had a strong interscan correlation (R 2 ≥ 0.99), with high repeatability for SUVmean and SUVmax (wCOV, 7.3% and 12.1%, respectively). High SUVs showed significantly improved wCOV relative to lower SUVs (P < 0.0001), indicating that high SUVs are more repeatable, relative to the magnitude of the underlying SUV. Repeatability for PSMA-TV and TL-PSMA, however, was low (wCOV ≥ 23.5%). Across all metrics for LN and bone lesions, interscan correlation was again strong (R 2 ≥ 0.98). Moreover, LN-based SUVmean also achieved the best wCOV (3.8%), which was significantly reduced when compared to osseous lesions (7.8%, P < 0.0001). This was also noted for SUVmax (wCOV, LN 8.8% vs. bone 12.0%, P < 0.03). On a compartment-based level, wCOVs for volumetric features were ≥22.8%, demonstrating no significant differences between LN and bone lesions (PSMA-TV, P =0.63; TL-PSMA, P =0.9). Findings on an entire tumor burden level were also corroborated in a hottest lesion analysis investigating the SUVmax of the most intense lesion per patient (R 2, 0.99; wCOV, 11.2%). Conclusion: In this prospective test-retest setting, SUV parameters demonstrated high repeatability, in particular in LNs, while volumetric parameters demonstrated low repeatability. Further, the large number of lesions and wide distribution of SUVs included in this analysis allowed for the demonstration of a dependence of repeatability on SUV, with higher SUVs having more robust repeatability.

Combined Longitudinal Clinical and Autopsy Phenomic Assessment in Lethal Metastatic Prostate Cancer: Recommendations for Advancing Precision Medicine.

BACKGROUND: Systematic identification of data essential for outcome prediction in metastatic prostate cancer (mPC) would accelerate development of precision oncology. OBJECTIVE: To identify novel phenotypes and features associated with mPC outcome, and to identify biomarker and data requirements to be tested in future precision oncology trials. DESIGN SETTING AND PARTICIPANTS: We analyzed deep longitudinal clinical, neuroendocrine expression, and autopsy data of 33 men who died from mPC between 1995 and 2004 (PELICAN33), and related findings to mPC biomarkers reported in the literature. INTERVENTION: Thirty-three men prospectively consented to participate in an integrated clinical-molecular rapid autopsy study of mPC. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Data exploration with correction for multiple testing and survival analysis from the time of diagnosis to time to death and time to first occurrence of severe pain as outcomes were carried out. The effect of seven complications on the modeled probability of dying within 2 yr after presenting with the complication was evaluated using logistic regression. RESULTS AND LIMITATIONS: Feature exploration revealed novel phenotypes related to mPC outcome. Four complications (pleural effusion, severe anemia, severe or controlled pain, and bone fracture) predict the likelihood of death within 2 yr. Men with Gleason grade group 5 cancers developed severe pain sooner than those with lower-grade tumors. Surprisingly, neuroendocrine (NE) differentiation was frequently observed in the setting of high serum prostate-specific antigen (PSA) levels (≥30 ng/ml). In 4/33 patients, no controlled (requiring analgesics) or severe pain was detected, and strikingly, 14/15 metastatic sites studied in these men did not express NE markers, suggesting an inverse relationship between NE differentiation and pain in mPC. Intracranial subdural metastasis is common (36%) and is usually clinically undetected. Categorization of "skeletal-related events" complications used in recent studies likely obscures the understanding of spinal cord compression and fracture. Early death from prostate cancer was identified in a subgroup of men with a low longitudinal PSA bandwidth. Cachexia is common (body mass index <0.89 in 24/31 patients) but limited to the last year of life. Biomarker review identified 30 categories of mPC biomarkers in need of winnowing in future trials. All findings require validation in larger cohorts, preferably alongside data from this study. CONCLUSIONS: The study identified novel outcome subgroups for future validation and provides "vision for mPC precision oncology 2020-2050" draft recommendations for future data collection and biomarker studies. PATIENT SUMMARY: To better understand variation in metastatic prostate cancer behavior, we assembled and analyzed longitudinal clinical and autopsy records in 33 men. We identified novel outcomes, phenotypes, and aspects of disease burden to be tested and refined in future trials.

Timing of Androgen Deprivation Treatment for Men with Biochemical Recurrent Prostate Cancer in the Context of Novel Therapies.

PURPOSE: There were 3 recent U.S. Food and Drug Administration approvals for drugs to be used in nonmetastatic castration resistant prostate cancer, a state that arises from the unproven start of continuous androgen deprivation therapy (ADT) for biochemical recurrent prostate cancer (BCR), before metastatic disease is evident. This report examines the outcome of men with BCR who defer ADT until time of metastasis. MATERIALS AND METHODS: Retrospective review of men diagnosed with clinically localized prostate cancer who underwent radical prostatectomy at Johns Hopkins Hospital and Walter Reed National Military Medical Center and developed BCR with a prostate specific antigen doubling time of not more than 10 months (806 patients). The primary end points were metastasis-free survival and overall survival from time of local treatment among men who delayed ADT until time of metastasis. RESULTS: The median metastasis-free survival of men with BCR and a prostate specific antigen doubling time <6 months and 10 months who delay ADT until metastasis is 144 months (95% CI 48-not reached) and 192 months (95% CI 72-not reached), respectively, with a median overall survival of 168 months (95% CI 96-276 months) and 204 months (95% CI 120-276), respectively. CONCLUSIONS: Metastasis-free survival and overall survival of men with BCR who delay hormone therapy is long. This underscores the need to reevaluate when to start primary ADT in this patient population.

Prospective, Single-Arm Trial Evaluating Changes in Uptake Patterns on Prostate-Specific Membrane Antigen-Targeted 18F-DCFPyL PET/CT in Patients with Castration-Resistant Prostate Cancer Starting Abiraterone or Enzalutamide.

PET with small molecules targeting prostate-specific membrane antigen (PSMA) is being adopted as a clinical standard for prostate cancer imaging. In this study, we evaluated changes in uptake on PSMA-targeted PET in men starting abiraterone or enzalutamide. Methods: This prospective, single-arm, 2-center, exploratory clinical trial enrolled men with metastatic castration-resistant prostate cancer initiating abiraterone or enzalutamide. Each patient was imaged with 18F-DCFPyL at baseline and within 2-4 mo after starting therapy. Patients were followed for up to 48 mo from enrollment. A central review evaluated baseline and follow-up PET scans, recording change in SUVmax at all disease sites and classifying the pattern of change. Two parameters were derived: the δ-percent SUVmax (DPSM) of all lesions and the δ-absolute SUVmax (DASM) of all lesions. Kaplan-Meier curves were used to estimate time to therapy change (TTTC) and overall survival (OS). Results: Sixteen evaluable patients were accrued to the study. Median TTTC was 9.6 mo (95% CI, 6.9-14.2), and median OS was 28.6 mo (95% CI, 18.3-not available [NA]). Patients with a mixed-but-predominantly-increased pattern of radiotracer uptake had a shorter TTTC and OS. Men with a low DPSM had a median TTTC of 12.2 mo (95% CI, 11.3-NA) and a median OS of 37.2 mo (95% CI, 28.9-NA), whereas those with a high DPSM had a median TTTC of 6.5 mo (95% CI, 4.6-NA, P = 0.0001) and a median OS of 17.8 mo (95% CI, 13.9-NA, P = 0.02). Men with a low DASM had a median TTTC of 12.2 mo (95% CI, 11.3-NA) and a median OS of NA (95% CI, 37.2 mo-NA), whereas those with a high DASM had a median TTTC of 6.9 mo (95% CI, 6.1-NA, P = 0.003) and a median OS of 17.8 mo (95% CI, 13.9-NA, P = 0.002). Conclusion: Findings on PSMA-targeted PET 2-4 mo after initiation of abiraterone or enzalutamide are associated with TTTC and OS. Development of new lesions or increasing intensity of radiotracer uptake at sites of baseline disease are poor prognostic findings suggesting shorter TTTC and OS.

TRANSFORMER: A Randomized Phase II Study Comparing Bipolar Androgen Therapy Versus Enzalutamide in Asymptomatic Men With Castration-Resistant Metastatic Prostate Cancer.

PURPOSE: Prostate cancer (PCa) becomes resistant to androgen ablation through adaptive upregulation of the androgen receptor in response to the low-testosterone microenvironment. Bipolar androgen therapy (BAT), defined as rapid cycling between high and low serum testosterone, disrupts this adaptive regulation in castration-resistant PCa (CRPC). METHODS: The TRANSFORMER (Testosterone Revival Abolishes Negative Symptoms, Fosters Objective Response and Modulates Enzalutamide Resistance) study is a randomized study comparing monthly BAT (n = 94) with enzalutamide (n = 101). The primary end point was clinical or radiographic progression-free survival (PFS); crossover was permitted at progression. Secondary end points included overall survival (OS), prostate-specific antigen (PSA) and objective response rates, PFS from randomization through crossover (PFS2), safety, and quality of life (QoL). RESULTS: The PFS was 5.7 months for both arms (hazard ratio [HR], 1.14; 95% CI, 0.83 to 1.55; P = .42). For BAT, 50% decline in PSA (PSA50) was 28.2% of patients versus 25.3% for enzalutamide. At crossover, PSA50 response occurred in 77.8% of patients crossing to enzalutamide and 23.4% to BAT. The PSA-PFS for enzalutamide increased from 3.8 months after abiraterone to 10.9 months after BAT. The PFS2 for BAT→enzalutamide was 28.2 versus 19.6 months for enzalutamide→BAT (HR, 0.44; 95% CI, 0.22 to 0.88; P = .02). OS was 32.9 months for BAT versus 29.0 months for enzalutamide (HR, 0.95; 95% CI, 0.66 to 1.39; P = .80). OS was 37.1 months for patients crossing from BAT to enzalutamide versus 30.2 months for the opposite sequence (HR, 0.68; 95% CI, 0.36 to 1.28; P = .225). BAT adverse events were primarily grade 1-2. Patient-reported QoL consistently favored BAT. CONCLUSION: This randomized trial establishes meaningful clinical activity and safety of BAT and supports additional study to determine its optimal clinical integration. BAT can sensitize CRPC to subsequent antiandrogen therapy. Further study is required to confirm whether sequential therapy with BAT and enzalutamide can improve survival in men with CRPC.

Nivolumab plus ipilimumab, with or without enzalutamide, in AR-V7-expressing metastatic castration-resistant prostate cancer: A phase-2 nonrandomized clinical trial.

BACKGROUND: AR-V7-positive metastatic prostate cancer is a lethal phenotype with few treatment options and poor survival. METHODS: The two-cohort nonrandomized Phase 2 study of combined immune checkpoint blockade for AR-V7-expressing metastatic castration-resistant prostate cancer (STARVE-PC) evaluated nivolumab (3 mg/kg) plus ipilimumab (1 mg/kg), without (Cohort 1) or with (Cohort 2) the anti-androgen enzalutamide. Co-primary endpoints were safety and prostate-specific antigen (PSA) response rate. Secondary endpoints included time-to-PSA-progression-free survival (PSA-PFS), time-to-clinical/radiographic-PFS, objective response rate (ORR), PFS lasting greater than 24 weeks, and overall survival (OS). RESULTS: Thirty patients were treated with ipilimumab plus nivolumab (N = 15, Cohort 1, previously reported), or ipilimumab plus nivolumab and enzalutamide (N = 15, Cohort 2) in patients previously progressing on enzalutamide monotherapy. PSA response rate was 2/15 (13%) in cohort 1 and 0/15 in cohort 2, ORR was 2/8 (25%) in Cohort 1 and 0/9 in Cohort 2 in those with measureable disease, median PSA-PFS was 3.0 (95% confidence interval [CI]: 2.1-NR) in cohort 1 and 2.7 (95% CI: 2.1-5.9) months in cohort 2, and median PFS was 3.7 (95% CI: 2.8-7.5) in cohort 1 and 2.9 (95% CI: 1.3-5.8) months in cohort 2. Three of 15 patients in cohort 1 (20%, 95% CI: 7.1%-45.2%) and 4/15 patients (26.7%, 95% CI: 10.5%-52.4%) in cohort 2 achieved a durable PFS lasting greater than 24 weeks. Median OS was 8.2 (95% CI: 5.5-10.4) in cohort 1 and 14.2 (95% CI: 8.5-NA) months in cohort 2. Efficacy results were not statistically different between cohorts. Grade-3/4 adverse events occurred in 7/15 cohort 1 patients (46%) and 8/15 cohort 2 patients (53%). Combined cohort (N = 30) baseline alkaline phosphatase and cytokine analysis suggested improved OS for patients with lower alkaline phosphatase (hazards ratio [HR], 0.30; 95% CI: 0.11-0.82), lower circulating interleukin-7 (IL-7) (HR, 0.24; 95% Cl: 0.06-0.93) and IL-6 (HR, 0.13; 95% Cl: 0.03-0.52) levels, and higher circulating IL-17 (HR, 4.53; 95% CI: 1.47-13.93) levels. There was a trend towards improved outcomes in men with low sPD-L1 serum levels. CONCLUSION: Nivolumab plus ipilimumab demonstrated only modest activity in patients with AR-V7-expressing prostate cancer, and was not sufficient to justify further exploration in unselected patients. Stratification by baseline alkaline phosphatase and cytokines (IL-6, -7, and -17) may be prognostic for outcomes to immunotherapy.

Detection of Early Progression with 18F-DCFPyL PET/CT in Men with Metastatic Castration-Resistant Prostate Cancer Receiving Bipolar Androgen Therapy.

Bipolar androgen therapy (BAT) is an emerging treatment for metastatic castration-resistant prostate cancer (mCRPC). 18F-DCFPyL is a small-molecule PET radiotracer targeting prostate-specific membrane antigen (PSMA). We analyzed the utility of 18F-DCFPyL PET/CT in determining clinical response to BAT. Methods: Six men with mCRPC receiving BAT were imaged with 18F-DCFPyL PET/CT at baseline and after 3 mo of treatment. Progression by PSMA-targeted PET/CT was defined as the appearance of any new 18F-DCFPyL-avid lesion. Results: Three of 6 (50%) patients had progression on 18F-DCFPyL PET/CT. All 3 had stable disease or better on contemporaneous conventional imaging. Radiographic progression on CT or bone scanning was observed within 3 mo of progression on 18F-DCFPyL PET/CT. For the 3 patients who did not have progression on 18F-DCFPyL PET/CT, radiographic progression was not observed for at least 6 mo. Conclusion: New radiotracer-avid lesions on 18F-DCFPyL PET/CT in men with mCRPC undergoing BAT can indicate early progression.

Bipolar androgen therapy sensitizes castration-resistant prostate cancer to subsequent androgen receptor ablative therapy.

BACKGROUND: Cyclical, high-dose testosterone administration, termed bipolar androgen therapy (BAT), can induce clinical responses and restore sensitivity to androgen signalling inhibition in patients with previously treated castration-resistant prostate cancer (PCa) (CRPC). This trial evaluated whether BAT is a safe and effective first-line hormonal therapy for patients with CRPC. PATIENTS AND METHODS: In cohort C of this single-centre, open-label, phase II, multi-cohort trial (RE-sensitizing with Supraphysiologic Testosterone to Overcome REsistance study), 29 patients with CRPC received first-line hormonal therapy with 400 mg of testosterone cypionate intramuscularly every 28 days concurrent with a luteinising hormone-releasing hormone agonist/antagonist. The primary end-point of the study was the PSA50 response rate to BAT treatment. RESULTS: After treatment with BAT, four of 29 patients (14%; 95% confidence interval [CI]: 4-32%) experienced a PSA50 response. The median radiographic progression-free survival to BAT was 8.5 months (95% CI: 6.9-15.1) for patients with metastatic CRPC. After progression on BAT, 17 of 18 patients (94%; 95% CI: 73-100%) achieved a PSA50 response and 15 of 18 patients (83%; 95% CI: 59-96) achieved a PSA90 response on abiraterone or enzalutamide. Twelve of 15 patients (80%; 95% CI: 52-96) with metastatic CRPC remain on abiraterone or enzalutamide with a median duration of follow-up of 11.2 months. CONCLUSION: As first-line hormonal treatment for CRPC, BAT was well tolerated and resulted in prolonged disease stabilisation. After progression on BAT, patients had favourable responses to second-generation androgen receptor-targeted therapy. TRIAL REGISTRATION: ClinicalTrials.gov NCT02090114.

A Multicohort Open-label Phase II Trial of Bipolar Androgen Therapy in Men with Metastatic Castration-resistant Prostate Cancer (RESTORE): A Comparison of Post-abiraterone Versus Post-enzalutamide Cohorts.

BACKGROUND: Cyclic high-dose testosterone injections, also known as bipolar androgen therapy (BAT), is a novel treatment strategy for patients with metastatic castration-resistant prostate cancer (mCRPC). BAT has shown clinical activity in prior studies enrolling men with mCRPC and may potentially restore sensitivity to prior androgen receptor (AR)-targeted agents. OBJECTIVE: To evaluate the clinical activity of BAT in patients progressing on AR-targeted therapy as well as responses to abiraterone or enzalutamide upon rechallenge after BAT. DESIGN, SETTING, AND PARTICIPANTS: RESTORE is a multicohort phase II study enrolling asymptomatic mCRPC patients after abiraterone or enzalutamide at Johns Hopkins Hospital (NCT02090114). Participants (29 after abiraterone and 30 after enzalutamide) received 400 mg testosterone cypionate intramuscularly every 28 days, with ongoing luteinizing hormone-releasing hormone agonist/antagonist treatment (ie, BAT). Following progression on BAT, patients were rechallenged with their most recent AR-targeted therapy. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Coprimary endpoints were >50% decline in PSA from baseline (PSA50) responses to BAT and following AR-targeted therapy rechallenge. Outcomes in the post-abiraterone cohort are presented, as well as updated results from the post-enzalutamide cohort and an exploratory AR-V7 analysis. RESULTS AND LIMITATIONS: No statistically significant difference in PSA50 response rates to BAT was observed (30% [post-enzalutamide cohort] vs 17% [post-abiraterone cohort], p = 0.4). However, PSA50 responses to AR-targeted therapy rechallenge were higher in the post-enzalutamide cohort (68% vs 16%, p = 0.001). The median time from enrollment to progression following rechallenge with AR-targeted therapy (ie, progression-free survival 2; PFS2) was longer in the post-enzalutamide versus post-abiraterone patients (12.8 vs 8.1 mo, p = 0.04). Outcomes were worse in patients with detectable AR-V7 in circulating tumor cells (median PFS2: 10.3 vs 7.1 mo, p = 0.005). CONCLUSIONS: BAT shows clinical activity in mCRPC patients and may be more effective at resensitizing to enzalutamide versus abiraterone. PATIENT SUMMARY: BAT is well tolerated in metastatic castration-resistant prostate cancer patients. The type of prior AR-targeted therapy might affect response to BAT as well as AR-therapy rechallenge. BAT followed by AR-targeted therapy rechallenge did not improve outcomes in AR-V7-positive patients.

A phase II randomized trial of RAdium-223 dichloride and SABR Versus SABR for oligomEtastatic prostate caNcerS (RAVENS).

BACKGROUND: Metastasis directed therapy (MDT) for patients with oligometastatic disease is associated with improvements in progression free survival (PFS) and overall survival (OS) compared to systemic therapy alone. Additionally, within a prostate-cancer-specific cohort, MDT is able to forestall initiation of androgen deprivation therapy (ADT) in men with hormone-sensitive, oligometastatic prostate cancer (HSOPCa) compared to observation. While MDT appears to be safe and effective in HSOPCa, a large percentage of men will eventually have disease recurrence. Patterns of failure in HSOPCa demonstrate patients tend to have recurrence in the bone following MDT, raising the question of sub-clinically-apparent osseous disease. Radium-223 dichloride is a radiopharmaceutical with structural similarity to calcium, allowing it to be taken up by bone where it emits alpha particles, and therefore might have utility in the treatment of micrometastatic osseous disease. Therefore, the primary goal of the phase II RAVENS trial is to evaluate the efficacy of MDT + radium-223 dichloride in prolonging progression free survival in men with HSOPCa. METHODS: Patients with HSOPCa and 3 or less metastases with at least 1 bone metastasis will be randomized 1:1 to stereotactic ablative radiation (SABR, also known as stereotactic body radiation therapy (SBRT)) alone vs SABR + radium-223 dichloride with a minimization algorithm to balance assignment by institution, primary intervention, prior hormonal therapy, and PSA doubling time. SABR is delivered in one to five fractions and patients in the SABR + radium-223 dichloride arm will receive six infusions of radium-223 dichloride at four-week intervals. The primary end point is progression free survival. The secondary clinical endpoints include toxicity and quality of life assessments, local control at 12 months, locoregional progression, time to distant progression, time to new metastasis, and duration of response. DISCUSSION: The RAVENS trial will be the first described phase II, non-blinded, randomized study to compare SABR +/- radium-223 dichloride in patients with HSOPCa and 3 or less metastases with at least one bone metastasis. The primary hypothesis is that SABR + radium-223 dichloride will increase median progression-free survival from 10 months in the SABR arm to 20 months in the SABR + radium-223 dichloride arm. TRIAL REGISTRATIONS: Clinicaltrials.gov. Identifier: NCT04037358. Date of Registration: July 30, 2019. Date of First Participant Enrolled: August 9, 2019. Date of Last Approved Amendment: October 16, 2019. Protocol Version: Version 5.

Comparative Survival of Asian and White Metastatic Castration-Resistant Prostate Cancer Men Treated With Docetaxel.

There are few data regarding disparities in overall survival (OS) between Asian and white men with metastatic castration-resistant prostate cancer (mCRPC). We compared OS of Asian and white mCRPC men treated in phase III clinical trials with docetaxel and prednisone (DP) or a DP-containing regimen. Individual participant data from 8820 men with mCRPC randomly assigned on nine phase III trials to receive DP or a DP-containing regimen were combined. Men enrolled in these trials had a diagnosis of prostate adenocarcinoma. The median overall survival was 18.8 months (95% confidence interval [CI] = 17.4 to 22.1 months) and 21.2 months (95% CI = 20.8 to 21.7 months) for Asian and white men, respectively. The pooled hazard ratio for death for Asian men compared with white men, adjusted for baseline prognostic factors, was 0.95 (95% CI = 0.84 to 1.09), indicating that Asian men were not at increased risk of death. This large analysis showed that Asian men did not have shorter OS duration than white men treated with docetaxel.

Telomere lengths differ significantly between small-cell neuroendocrine prostate carcinoma and adenocarcinoma of the prostate.

Small-cell neuroendocrine carcinoma (SCNC) of the prostate is an aggressive subtype with frequent TP53 mutation and RB1 inactivation; however, the molecular phenotype remains an area of investigation. Here, we compared telomere lengths in prostatic SCNC and usual-type prostatic adenocarcinoma (AdCa). We studied 32 cases of prostatic SCNC (including 11 cases with concurrent AdCa) and 347 cases of usual-type AdCa on tissue microarrays. Telomere lengths in tumor cells were qualitatively compared with those in normal cells using a telomere-specific fluorescence in situ hybridization assay. ERG, PTEN, and TP53 status were assessed in a proportion of cases using genetically validated immunohistochemistry protocols. Clinicopathological and molecular characteristics of cases were compared between the telomere groups using the chi-square test.A significantly higher proportion of prostatic SCNC cases (50%, 16/32) showed normal/long telomeres compared with AdCa cases (11%, 39/347; P < 0.0001). In 82% (9/11) of cases with concurrent SCNC and AdCa, the paired components were concordant for telomere length status. Among AdCa cases, the proportion of cases with normal/long telomeres significantly increased with increasing tumor grade group (P = 0.01) and pathologic stage (P = 0.02). Cases with normal/long telomeres were more likely to be ERG positive (P = 0.04) and to have TP53 missense mutation (P = 0.01) than cases with short telomeres.Normal or long telomere lengths are significantly more common in prostatic SCNC than in AdCa and are similar between concurrent SCNC and AdCa tumors, supporting a common origin. Among AdCa cases, longer telomere lengths are significantly associated with high-risk pathologic and molecular features.

Prostate Specific Antigen and Prostate Specific Antigen Doubling Time Predict Findings on 18F-DCFPyL Positron Emission Tomography/Computerized Tomography in Patients with Biochemically Recurrent Prostate Cancer.

PURPOSE: Prostate specific membrane antigen targeted 18F-DCFPyL positron emission tomography/computerized tomography may offer superior image quality and sensitivity for the detection of biochemically recurrent prostate cancer. We examined the association of Gleason sum, serum prostate specific antigen and prostate specific antigen doubling time with any detectable and pelvic confined disease in patients with biochemically recurrent prostate cancer. MATERIALS AND METHODS: Data from 108 patients with biochemically recurrent prostate cancer after radical prostatectomy who underwent prostate specific membrane antigen targeted 18F-DCFPyL positron emission tomography/computerized tomography were analyzed. Data were collected on positive positron emission tomography findings as well as pelvic confined disease. Associations between Gleason sum, prostate specific antigen and prostate specific antigen doubling time were retrospectively explored. RESULTS: Serum prostate specific antigen was associated with positive prostate specific membrane antigen targeted imaging as continuous (OR 3.08, 95% CI 1.60-7.95, p=0.005) and categorical values (ie prostate specific antigen greater than 2.0 to 5.0 vs 0.5 ng/ml or less, OR 16.92, 95% CI 3.13-315.81, p=0.008). No relationship between Gleason sum or prostate specific antigen doubling time with overall positive imaging was observed. Patients with a prostate specific antigen greater than 2.0 to 5.0 ng/ml were significantly less likely to be diagnosed with pelvic confined disease compared with the 0.5 ng/ml or less subgroup (OR 0.21, 95% CI 0.06-0.69, p=0.013). A prostate specific antigen doubling time of 9 months or more (OR 4.20, 95% CI 1.57-11.89, p=0.005) or prostate specific antigen doubling time of 12 months or more (OR 3.03, 95% CI 1.12-8.76, p=0.033) was significantly associated with pelvic confined disease. No relationship between Gleason sum and pelvic confined disease was observed. CONCLUSIONS: Absolute prostate specific antigen was positively associated with the presence of findings on prostate specific membrane antigen targeted imaging and negatively associated with pelvic confined disease. Prostate specific antigen doubling time did not predict for overall disease detection, but long prostate specific antigen doubling times were associated with pelvic confined prostate cancer.

Outcomes of Observation vs Stereotactic Ablative Radiation for Oligometastatic Prostate Cancer: The ORIOLE Phase 2 Randomized Clinical Trial.

Importance: Complete metastatic ablation of oligometastatic prostate cancer may provide an alternative to early initiation of androgen deprivation therapy (ADT). Objective: To determine if stereotactic ablative radiotherapy (SABR) improves oncologic outcomes in men with oligometastatic prostate cancer. Design, Setting, and Participants: The Observation vs Stereotactic Ablative Radiation for Oligometastatic Prostate Cancer (ORIOLE) phase 2 randomized study accrued participants from 3 US radiation treatment facilities affiliated with a university hospital from May 2016 to March 2018 with a data cutoff date of May 20, 2019, for analysis. Of 80 men screened, 54 men with recurrent hormone-sensitive prostate cancer and 1 to 3 metastases detectable by conventional imaging who had not received ADT within 6 months of enrollment or 3 or more years total were randomized. Interventions: Patients were randomized in a 2:1 ratio to receive SABR or observation. Main Outcomes and Measures: The primary outcome was progression at 6 months by prostate-specific antigen level increase, progression detected by conventional imaging, symptomatic progression, ADT initiation for any reason, or death. Predefined secondary outcomes were toxic effects of SABR, local control at 6 months with SABR, progression-free survival, Brief Pain Inventory (Short Form)-measured quality of life, and concordance between conventional imaging and prostate-specific membrane antigen (PSMA)-targeted positron emission tomography in the identification of metastatic disease. Results: In the 54 men randomized, the median (range) age was 68 (61-70) years for patients allocated to SABR and 68 (64-76) years for those allocated to observation. Progression at 6 months occurred in 7 of 36 patients (19%) receiving SABR and 11 of 18 patients (61%) undergoing observation (P = .005). Treatment with SABR improved median progression-free survival (not reached vs 5.8 months; hazard ratio, 0.30; 95% CI, 0.11-0.81; P = .002). Total consolidation of PSMA radiotracer-avid disease decreased the risk of new lesions at 6 months (16% vs 63%; P = .006). No toxic effects of grade 3 or greater were observed. T-cell receptor sequencing identified significant increased clonotypic expansion following SABR and correlation between baseline clonality and progression with SABR only (0.082085 vs 0.026051; P = .03). Conclusions and Relevance: Treatment with SABR for oligometastatic prostate cancer improved outcomes and was enhanced by total consolidation of disease identified by PSMA-targeted positron emission tomography. SABR induced a systemic immune response, and baseline immune phenotype and tumor mutation status may predict the benefit from SABR. These results underline the importance of prospective randomized investigation of the oligometastatic state with integrated imaging and biological correlates. Trial Registration: ClinicalTrials.gov Identifier: NCT02680587.

Extreme responses to immune checkpoint blockade following bipolar androgen therapy and enzalutamide in patients with metastatic castration resistant prostate cancer.

BACKGROUND: Immune checkpoint inhibition has been shown to have limited efficacy in patients with metastatic prostate cancer. Prostate cancers that harbor certain homologous recombination (HR) DNA repair gene mutations, inactivating CDK12 mutations or have underlying mismatch repair deficiency may be effectively treated with immunotherapy. Combination therapy may improve clinical response rates to immune checkpoint blockade. We observed profound prostate-specific antigen (PSA) and/or objective responses to immune checkpoint blockade following prior treatment with bipolar androgen therapy (BAT) and enzalutamide. METHODS: We report three cases of patients with metastatic castration resistant prostate cancer (mCRPC) undergoing therapy with anti-PD-1 inhibitors. All patients underwent both somatic molecular testing and germline genetic testing. RESULTS: Two of the three patients with mCRPC harbored an inactivating mutation in an HR DNA repair gene (BRCA2, ATM). No patient demonstrated mismatch repair deficiency, nor were CDK12 alterations present. All three patients had been treated with BAT and enzalutamide before immune checkpoint blockade, a paradoxical approach for the treatment of mCRPC developed by our group. CONCLUSIONS: These cases of mCRPC suggest that immune checkpoint blockade may have therapeutic potential in patients with prostate cancer, especially following immune activation ("priming") using BAT and enzalutamide.