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.

Transperineal prostate biopsy with cognitive magnetic resonance imaging/biplanar ultrasound fusion: description of technique and early results.

OBJECTIVE: To describe our technique and early results performing transperineal prostate biopsy using cognitive magnetic resonance imaging (MRI)/biplanar ultrasound fusion. Key components of this technique include use of the PrecisionPoint Transperineal Access System (Perineologic, Cumberland, MD) and simultaneous transrectal ultrasound guidance in the axial and sagittal planes. PATIENTS AND METHODS: In total, 95 patients (38 studied retrospectively and 57 studied prospectively) underwent a transperineal MRI-targeted prostate biopsy using the technique detailed in this manuscript. All biopsies were performed by a single urologist (MAG). Data were collected with respect to cancer detection rates, tolerability, and complications. The subset of patients who were studied prospectively was assessed for complications by telephone interviews performed at 4-6 days and 25-31 days following the prostate biopsy. RESULTS: Between February 2018 and June 2019, 95 men underwent a transperineal prostate biopsy using MRI/biplanar ultrasound fusion guidance. Patients had a total of 124 PI-RADS 3-5 lesions that were targeted for biopsy. In total, 108 (87.1%) lesions were found to harbor prostate cancer of any grade. Grade group ≥ 2 prostate cancer was found in 81 (65.3%) of targeted lesions. The detection rates for grade group ≥ 1 and grade group ≥ 2 prostate cancer rose with increasing PI-RADS score. In 65 (68.4%) cases, the patient's highest grade prostate cancer was found within an MRI target. Additionally, 12 of 55 (21.8%) patients who were found to have no or grade group 1 prostate cancer on systematic biopsy were upgraded to grade group ≥ 2 prostate cancer with MRI targeting. Only 1 (1.1%) patient received periprocedural antibiotics and no patient experienced an infectious complication. Self-limited hematuria and hematospermia were commonly reported following the procedure (75.4% and 40.4%, respectively) and only 1 (1.1%) patient developed urinary retention. CONCLUSIONS: We demonstrate the safety and feasibility of performing transperineal prostate biopsy using cognitive MRI/biplanar ultrasound fusion guidance. The described technique affords the safety benefits of the transperineal approach as well as obviates the need for a formal fusion platform. Additionally, this method can conveniently be performed under local anesthesia with acceptable tolerability.

Perirectal hydrogel spacer placement prior to prostate radiation therapy using a probe-mounted needle guide.

In this report we describe our successful adoption of a single-use, probe-mounted, needle guide for perirectal hydrogel spacer placement prior to radiation therapy for prostate cancer. Use of this device eliminates the need for a mechanical stepper unit and facilitates perirectal hydrogel placement by ensuring alignment of the injection needle with the ultrasound probe.

A pilot trial of pembrolizumab plus prostatic cryotherapy for men with newly diagnosed oligometastatic hormone-sensitive prostate cancer.

BACKGROUND: Monotherapy with immune checkpoint inhibitors has generally been unsuccessful in men with advanced prostate cancer. Preclinical data support the notion that cryotherapy may improve immune-mediated and anti-tumor responses. The objective of this study was to assess the safety and feasibility of whole-prostate gland cryotherapy combined with pembrolizumab and androgen deprivation in men with oligometastatic hormone-sensitive prostate cancer. METHODS: This single-institution, pilot trial recruited 12 patients with newly diagnosed oligometastatic prostate cancer between 2015 and 2016. Patients underwent whole-prostate cryoablation combined with short-term androgen deprivation (eight months) and pembrolizumab (6 doses). The primary clinical endpoints were the number of patients with a PSA level of <0.6 ng/mL at one year and the frequency of adverse events. Other outcome measures included progression-free survival and systemic therapy-free survival. Exploratory analyses included PD-L1 protein expression. RESULTS: Forty two percent (5/12) of patients had a PSAs of <0.6 ng/mL at one year though only 2 of these patients had recovered their testosterone at this time point. Median progression-free survival was 14 months, and median systemic therapy-free survival was 17.5 months. PD-L1 expression was not detectable by IHC in patients with evaluable tissue. All adverse events were grade ≤2, and there were no apparent complications from cryotherapy. CONCLUSIONS: Whole-prostate cryoablation combined with short-term androgen deprivation and pembrolizumab treatment was well tolerated and no safety concerns were observed in men with oligometastatic prostate cancer. Though local disease appeared effectively treated in the majority of men, the regimen only infrequency led to sustained disease control following testosterone recovery.

Ipilimumab plus nivolumab and DNA-repair defects in AR-V7-expressing metastatic prostate cancer.

AR-V7-expressing metastatic prostate cancer is an aggressive phenotype with poor progression-free survival (PFS) and overall survival (OS). Preliminary evidence suggests that AR-V7-positive tumors may be enriched for DNA-repair defects, perhaps rendering them more sensitive to immune-checkpoint blockade. We enrolled 15 metastatic prostate cancer patients with AR-V7-expressing circulating tumor cells into a prospective phase-2 trial. Patients received nivolumab 3 mg/kg plus ipilimumab 1 mg/kg every 3 weeks for four doses, then maintenance nivolumab 3 mg/kg every 2 weeks. Targeted next-generation sequencing was performed to determine DNA-repair deficiency (DRD) status. Outcomes included PSA response rates, objective response rates (ORR), PSA progression-free survival (PSA-PFS), clinical/radiographic PFS and OS. Median age of participants was 65, median PSA was 115 ng/mL, 67% had visceral metastases, and 60% had ≥4 prior systemic therapies. Six of 15 men (40%) had DRD mutations (three in BRCA2, two in ATM, one in ERCC4; none had microsatellite instability). Overall, the PSA response rate was 2/15 (13%), ORR was 2/8 (25%) in those with measurable disease, median PSA-PFS was 3.0 (95%CI 2.1-NR) months, PFS was 3.7 (95%CI 2.8-7.5) months, and OS was 8.2 (95%CI 5.5-10.4) months. Outcomes appeared generally better in DRD+ vs. DRD- tumors with respect to PSA responses (33% vs. 0%; P=0.14, nonsignificant), ORR (40% vs. 0%; P=0.46, nonsignificant), PSA-PFS (HR 0.19; P<0.01, significant), PFS (HR 0.31; P=0.01, significant), and OS (HR 0.41; P=0.11, nonsignificant). There were no new safety concerns. Ipilimumab plus nivolumab demonstrated encouraging efficacy in AR-V7-positive prostate cancers with DRD mutations, but not in the overall study population.

Pharmacodynamic and pharmacokinetic neoadjuvant study of hedgehog pathway inhibitor Sonidegib (LDE-225) in men with high-risk localized prostate cancer undergoing prostatectomy.

PURPOSE: To determine the pharmacodynamic effects of Sonidegib (LDE-225) in prostate tumor tissue from men with high-risk localized prostate cancer, by comparing pre-surgical core-biopsy specimens to tumor tissue harvested post-treatment at prostatectomy. METHODS: We conducted a prospective randomized (Sonidegib vs. observation) open-label translational clinical trial in men with high-risk localized prostate cancer undergoing radical prostatectomy. The primary endpoint was the proportion of patients in each arm who achieved at least a two-fold reduction in GLI1 mRNA expression in post-treatment versus pre-treatment tumor tissue. Secondary endpoints included the effect of pre-surgical treatment with Sonidegib on disease progression following radical prostatectomy, and safety. RESULTS: Fourteen men were equally randomized (7 per arm) to either neoadjuvant Sonidegib or observation for 4 weeks prior to prostatectomy. Six of seven men (86%) in the Sonidegib arm (and none in the control group) achieved a GLI1 suppression of at least two-fold. In the Sonidegib arm, drug was detectable in plasma and in prostatic tissue; and median intra-patient GLI1 expression decreased by 63-fold, indicating potent suppression of Hedgehog signaling. Sonidegib was well tolerated, without any Grade 3-4 adverse events observed. Disease-free survival was comparable among the two arms (HR = 1.50, 95% CI 0.26-8.69, P = 0.65). CONCLUSIONS: Hedgehog pathway activity (as measured by GLI1 expression) was detectable at baseline in men with localized high-risk prostate cancer. Sonidegib penetrated into prostatic tissue and induced a >60-fold suppression of the Hedgehog pathway. The oncological benefit of Hedgehog pathway inhibition in prostate cancer remains unclear.

Pharmacodynamic study of the oral hedgehog pathway inhibitor, vismodegib, in patients with metastatic castration-resistant prostate cancer.

PURPOSE: Hedgehog (Hh) pathway signaling has been implicated in prostate cancer tumorigenesis and metastatic development and may be upregulated even further in the castration-resistant state. We hypothesized that antagonism of the Hh pathway with vismodegib in men with metastatic castration-resistant prostate cancer (mCRPC) would result in pathway engagement, inhibition and perhaps induce measurable clinical responses in patients. METHODS: This is a single-arm study of oral daily vismodegib in men with mCRPC. All patients were required to have biopsies of the tumor and skin (a surrogate tissue) at baseline and after 4 weeks of therapy. Ten patients were planned for enrollment. The primary outcome was the pharmacodynamic assessment of Gli1 mRNA suppression with vismodegib in tumor tissue. Secondary outcomes included PSA response rates, progression-free survival (PFS), overall survival (OS) and safety. RESULTS: Nine patients were enrolled. Gli1 mRNA was significantly suppressed by vismodegib in both tumor tissue (4/7 evaluable biopsies, 57%) and benign skin biopsies (6/8 evaluable biopsies, 75%). The median number of treatment cycles completed was three, with a median PFS of 1.9 months (95% CI 1.3, NA), and a median OS of 7.04 months (95% CI 3.4, NA). No patient achieved a PSA reduction or a measurable tumor response. Safety data were consistent with the known toxicities of vismodegib. CONCLUSIONS: Hh signaling, as measured by Gli1 mRNA expression in mCRPC tissues, was suppressed with vismodegib in the majority of patients. Despite this pharmacodynamic response that indicated target inhibition in some patients, there was no apparent signal of clinical activity. Vismodegib will not be developed further as monotherapy in mCRPC.