Apalutamide efficacy, safety and wellbeing in older patients with advanced prostate cancer from Phase 3 randomised clinical studies TITAN and SPARTAN.

BACKGROUND: Apalutamide plus androgen-deprivation therapy (ADT) improved outcomes in metastatic castration-sensitive prostate cancer (mCSPC) and non-metastatic castration-resistant PC (nmCRPC) in the Phase 3 randomised TITAN and SPARTAN studies, respectively, and maintained health-related quality of life (HRQoL). Apalutamide treatment effect by patient age requires assessment. METHODS: Post-hoc analysis assessed patients receiving 240 mg/day apalutamide (525 TITAN and 806 SPARTAN) or placebo (527 TITAN and 401 SPARTAN) with ongoing ADT, stratified by age groups. Prostate-specific antigen declines, radiographic progression-free survival, metastasis-free survival, overall survival (OS), HRQoL and safety were assessed using descriptive statistics, Kaplan-Meier method, Cox proportional-hazards model and mixed-effects model for repeated measures. RESULTS: Hazard ratios (95% confidence intervals) generally favoured apalutamide plus ADT versus ADT alone across all endpoints regardless of age; e.g., OS values were 0.57 (0.40-0.80), 0.70 (0.54-0.91) and 0.74 (0.40-1.39) (TITAN) and 0.39 (0.19-0.78), 0.89 (0.69-1.16) and 0.81 (0.58-1.15) (SPARTAN) in patients aged <65, 65-79 and ≥80 years. Regardless of age, apalutamide also maintained HRQoL and was tolerated well with a potential trend in rates of adverse events increasing with age. Limitations include post-hoc nature and variability in sample size of age groups. CONCLUSIONS: Apalutamide plus ADT was an effective and well-tolerated option maintaining HRQoL in patients with mCSPC and nmCRPC regardless of age. CLINICAL TRIAL REGISTRATION: TITAN (NCT02489318); SPARTAN (NCT01946204).

Evolution of structural rearrangements in prostate cancer intracranial metastases.

Intracranial metastases in prostate cancer are uncommon but clinically aggressive. A detailed molecular characterization of prostate cancer intracranial metastases would improve our understanding of their pathogenesis and the search for new treatment strategies. We evaluated the clinical and molecular characteristics of 36 patients with metastatic prostate cancer to either the dura or brain parenchyma. We performed whole genome sequencing (WGS) of 10 intracranial prostate cancer metastases, as well as WGS of primary prostate tumors from men who later developed metastatic disease (n = 6) and nonbrain prostate cancer metastases (n = 36). This first whole genome sequencing study of prostate intracranial metastases led to several new insights. First, there was a higher diversity of complex structural alterations in prostate cancer intracranial metastases compared to primary tumor tissues. Chromothripsis and chromoplexy events seemed to dominate, yet there were few enrichments of specific categories of structural variants compared with non-brain metastases. Second, aberrations involving the AR gene, including AR enhancer gain were observed in 7/10 (70%) of intracranial metastases, as well as recurrent loss of function aberrations involving TP53 in 8/10 (80%), RB1 in 2/10 (20%), BRCA2 in 2/10 (20%), and activation of the PI3K/AKT/PTEN pathway in 8/10 (80%). These alterations were frequently present in tumor tissues from other sites of disease obtained concurrently or sequentially from the same individuals. Third, clonality analysis points to genomic factors and evolutionary bottlenecks that contribute to metastatic spread in patients with prostate cancer. These results describe the aggressive molecular features underlying intracranial metastasis that may inform future diagnostic and treatment approaches.

Metastatic Hormone-Sensitive Prostate Cancer: Toward an Era of Adaptive and Personalized Treatment.

The advent of more effective treatment combinations for metastatic hormone-sensitive prostate cancer (mHSPC) has been built on successes in therapy development for metastatic, castration-resistant prostate cancer (mCRPC). Both disease phases hold similar challenges and questions. Is there an optimal therapy sequence to maximize disease control and balance treatment burden? Are there clinical and biologically based subgroups that inform personalized and/or adaptive strategies? How can clinicians interpret data from clinical trials in the context of rapidly evolving technologies? Herein, we review the contemporary landscape of treatment for mHSPC, including disease subgroups informing both intensification and potential deintensification strategies. Furthermore, we provide current insights into the complex biology of mHSPC and discuss the potential clinical application of biomarkers to guide therapy selection and the development of novel personalized approaches.

Gender and Patient Satisfaction in a Veterans Health Administration Outpatient Chemotherapy Unit.

Background: Our objective was to explore whether differences in patient satisfaction based on gender exist at the Veterans Affairs Portland Health Care System (VAPHCS) outpatient chemotherapy infusion unit. Methods: Veterans who received outpatient infusion treatments at the VAPHCS outpatient chemotherapy infusion unit from 2018 to 2020 were invited to take an anonymous survey. Response differences were analyzed using Fisher exact and Welch t tests. Male and female patient lists were first generated based on Computerized Patient Record System designation, then defined and results reported based on gender self-identification from survey responses. Results: The survey was conducted over a 2-week period during January and February of 2021. In total, 69 veterans were contacted: 21 (70%) of 30 female and 20 (51%) of 39 male veterans completed the survey. Most (62%) female patients were aged < 65 years, and 52% were treated for breast cancer. Most (90%) male patients were aged ≥ 65 years, and most commonly treated for prostate cancer (20%) or a hematologic malignancy (20%). Using our survey, patient satisfaction (SD) was 8.7 (2.2) on a 10-point scale among women, and 9.6 (0.6) among men (P = .11). History of sexual abuse or harassment was reported by 86% of women compared with 10% of men (P < .001). Women reported feeling uncomfortable around other patients in the infusion unit compared with men (29% vs 0%; P = .02) and discomfort in relaying uncomfortable feelings to a clinician (29% vs 0%; P = .02). Conclusions: Gender seems to be related to how veterans with cancer perceive their ambulatory cancer care. This may be due to the combination of a high history of sexual abuse and/or harassment among women who represent a minority of the total infusion unit population, the majority of whom receive treatment for a primarily gender-specific breast malignancy. Analysis was limited by the small sample size of women, many with advanced malignancy.

Composition of gastrointestinal microbiota in association with treatment response in individuals with metastatic castrate resistant prostate cancer progressing on enzalutamide and initiating treatment with anti-PD-1 (pembrolizumab).

Recent studies in cancer patients and animal models demonstrate that intestinal microbiota influence the therapeutic efficacy of cancer treatments, including immune checkpoint inhibition. However, no studies to-date have investigated relationships between gastrointestinal microbiota composition and response to checkpoint inhibition in advanced metastatic castrate resistant prostate cancer (mCRPC). We performed 16S rRNA gene sequencing of fecal DNA from 23 individuals with mCRPC progressing on enzalutamide and just prior to treatment with anti-PD-1 (pembrolizumab) to determine whether certain features of the microbiome are associated with treatment response (defined as serum PSA decrease >50% at any time on treatment or radiographic response per RECIST V.1.1). Global bacterial composition was similar between responders and non-responders, as assessed by multiple alpha and beta diversity metrics. However, certain bacterial taxa identified by sequencing across multiple 16S rRNA hypervariable regions were consistently associated with response, including the archetypal oral bacterium Streptococcus salivarius. Quantitative PCR (qPCR) of DNA extracts from fecal samples confirmed increased Streptococcus salivarius fecal levels in responders, whereas qPCR of oral swish DNA extracts showed no relationship between oral Streptococcus salivarius levels and response status. Contrary to previous reports in other cancer types, Akkermansia muciniphila levels were reduced in responder samples as assessed by both 16S rRNA sequencing and qPCR. We further analyzed our data in the context of a previously published "integrated index" describing bacteria associated with response and non-response to checkpoint inhibition. We found that the index was not reflective of response status in our cohort. Lastly, we demonstrate little change in the microbiome over time, and with pembrolizumab treatment. Our results suggest that the association between fecal microbiota and treatment response to immunotherapy may be unique to cancer type and/or previous treatment history.

Androgen receptor activity in T cells limits checkpoint blockade efficacy.

Immune checkpoint blockade has revolutionized the field of oncology, inducing durable anti-tumour immunity in solid tumours. In patients with advanced prostate cancer, immunotherapy treatments have largely failed1-5. Androgen deprivation therapy is classically administered in these patients to inhibit tumour cell growth, and we postulated that this therapy also affects tumour-associated T cells. Here we demonstrate that androgen receptor (AR) blockade sensitizes tumour-bearing hosts to effective checkpoint blockade by directly enhancing CD8 T cell function. Inhibition of AR activity in CD8 T cells prevented T cell exhaustion and improved responsiveness to PD-1 targeted therapy via increased IFNγ expression. AR bound directly to Ifng and eviction of AR with a small molecule significantly increased cytokine production in CD8 T cells. Together, our findings establish that T cell intrinsic AR activity represses IFNγ expression and represents a novel mechanism of immunotherapy resistance.

Deep Prostate-specific Antigen Response following Addition of Apalutamide to Ongoing Androgen Deprivation Therapy and Long-term Clinical Benefit in SPARTAN.

BACKGROUND: Apalutamide plus androgen deprivation therapy (ADT) significantly improved metastasis-free survival (MFS), overall survival (OS), and time to prostate-specific antigen (PSA) progression in the placebo-controlled SPARTAN study of high-risk nonmetastatic castration-resistant prostate cancer (nmCRPC). OBJECTIVE: To assess the relationships between PSA kinetics, outcomes, and molecular subtypes in SPARTAN. DESIGN, SETTING, AND PARTICIPANTS: The authors conducted a post hoc analysis of nmCRPC patients randomized to receive apalutamide (n = 806) or placebo (n = 401) plus ADT and a subset stratified by molecular classifiers. INTERVENTION: Apalutamide 240 mg/d. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The association between PSA kinetics and MFS, OS, time to PSA progression, and molecular subtypes was evaluated using the landmark analysis and Kaplan-Meier methods. RESULTS AND LIMITATIONS: By 3 mo, PSA decreased in most apalutamide-treated patients and increased in most placebo-treated patients. After apalutamide, the median time to PSA nadir, confirmed ≥50% PSA reduction, ≥90% PSA reduction, and PSA ≤0.2 ng/ml were 7.4, 1.0, 1.9, and 2.8 mo, respectively. By 6 mo, 90%, 57%, and 32% of apalutamide patients had ≥50% PSA reduction, ≥90% PSA reduction, and PSA ≤0.2 ng/ml, respectively, while only 1.5% of placebo patients experienced ≥50% PSA reduction. PSA reductions were observed within 3 mo and up to 12 mo of apalutamide treatment, and were similar across molecular subtypes. Deep PSA responses (≥90% PSA reduction or PSA ≤0.2 ng/ml) at landmark 6-mo apalutamide treatment were significantly associated with improved time to PSA progression (hazard ratio {HR} [95% confidence interval {CI}] 0.25 [0.18-0.33] or 0.13 [0.08-0.21]), MFS (0.41 [0.29-0.57] or 0.3 [0.19-0.47]), and OS (0.45 [0.35-0.59] or 0.26 [0.18-0.38]; p < 0.001 for all). CONCLUSIONS: Apalutamide plus ADT produced rapid, deep, and durable PSA responses by 6-mo treatment regardless of assessed molecular prognostic markers. An early PSA response with apalutamide was associated with clinical benefits, supporting prognostic value of PSA monitoring. PATIENT SUMMARY: In this report, we describe how prostate-specific antigen (PSA) levels relate to outcomes in patients with nonmetastatic castration-resistant prostate cancer treated with apalutamide plus androgen deprivation therapy (ADT). We found that treatment with apalutamide plus ADT resulted in rapid, deep, and durable PSA responses in the majority of patients, including those with high-risk molecular subtypes, which were associated with improved survival.

Health-related Quality of Life at the SPARTAN Final Analysis of Apalutamide for Nonmetastatic Castration-resistant Prostate Cancer Patients Receiving Androgen Deprivation Therapy.

BACKGROUND: In SPARTAN, apalutamide improved metastasis-free and overall survival for patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) with a prostate-specific antigen doubling time of ≤10 mo. OBJECTIVE: We evaluated health-related quality of life (HRQoL) at the final analysis of the SPARTAN study. INTERVENTION: Patients received apalutamide (240 mg/d) or placebo in 28-d cycles. All patients continued androgen deprivation therapy (ADT). DESIGN, SETTING, AND PARTICIPANTS: A total of 1207 patients with nmCRPC were randomized 2:1 to apalutamide or placebo. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: HRQoL was assessed using Functional Assessment of Cancer Therapy-Prostate (FACT-P) and EQ-5D-3L questionnaires at day 1 of cycle 1 (predose/baseline), cycles 2-6, every two cycles during cycles 7-13, every four cycles thereafter, at the end of treatment, and every 4 mo after progression to 1 yr. Results are presented using descriptive statistics. A mixed model for repeated measures was fitted to estimate the mean scores at each scheduled visit during treatment. RESULTS: At final analysis, with 52 mo follow-up for survival, the median treatment duration was 32.9 mo for apalutamide and 11.5 mo for placebo. Patients had good baseline HRQoL. At each scheduled collection during treatment, >90% per group completed the questionnaires. The change in FACT-P total score from baseline to cycles 21 and 25 significantly favored apalutamide over placebo (p = 0.0138 and 0.0009, respectively). The apalutamide group generally maintained favorable FACT-P (total and subscales) and EQ-5D-3L scores, while placebo scores tended to decline over time (starting in cycles 11-13 and pronounced by cycles 21-25). Notably, patient-reported fatigue did not worsen with apalutamide. Most patients reported being "not at all bothered" by side effects, and bother did not increase over time with apalutamide or placebo. Patients receiving apalutamide had minimal change in side-effect bother following symptomatic adverse events. CONCLUSIONS: Final analysis of SPARTAN confirms that HRQoL is preserved in patients with nmCRPC receiving apalutamide plus ADT, but declines in patients receiving placebo plus ADT after approximately 1 yr. PATIENT SUMMARY: Responses from patients with prostate cancer who were included in the SPARTAN study indicated that treatment with apalutamide, even after the most extensive follow-up time possible, did not reduce their quality of life. These results, along with improved survival and longer time to the development of metastases (reported separately), confirm the benefits of apalutamide for patients with nonmetastatic castration-resistant prostate cancer.

Randomized Phase 2 Trial of Abiraterone Acetate Plus Prednisone, Degarelix, or the Combination in Men with Biochemically Recurrent Prostate Cancer After Radical Prostatectomy.

BACKGROUND: Phase 2 trial endpoints that can be utilized in high-risk biochemical recurrence (BCR) after prostatectomy as a way of more rapidly identifying treatments for phase 3 trials are urgently needed. The efficacy of abiraterone acetate plus prednisone (AAP) in BCR is unknown. OBJECTIVE: To compare the rates of complete biochemical responses after testosterone recovery after 8 mo of AAP and degarelix, a gonadotropin-releasing hormone antagonist, alone or in combination. DESIGN SETTING AND PARTICIPANTS: Patients with BCR (prostate-specific antigen [PSA] ≥1.0 ng/ml, PSA doubling time ≤9 mo, no metastases on standard imaging, and testosterone ≥150 ng/dl) after prostatectomy (with or without prior radiotherapy) were included in this study. INTERVENTION: Patients were randomized to AAP (arm 1), AAP with degarelix (arm 2), or degarelix (arm 3) for 8 mo, and monitored for 18 mo. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary endpoint was undetectable PSA with testosterone >150 ng/dl at 18 mo. Secondary endpoints were undetectable PSA at 8 mo and time to testosterone recovery. RESULTS AND LIMITATIONS: For the 122 patients enrolled, no difference was found between treatments for the primary endpoint (arm 1: 5.1% [95% confidence interval {CI}: 1-17%], arm 2: 17.1% [95% CI: 7-32%], arm 3: 11.9% [95% CI: 4-26%]; arm 1 vs 2, p = 0.93; arm 2 vs 3, p = 0.36). AAP therapy showed the shortest median time to testosterone recovery (36.0 wk [95% CI: 35.9-36.1]) relative to degarelix (52.9 wk [95% CI: 49.0-56.0], p < 0.001). Rates of undetectable PSA at 8 mo differed between AAP with degarelix and degarelix alone (p = 0.04), but not between AAP alone and degarelix alone (p = 0.12). Limitations of this study include a lack of long-term follow-up. CONCLUSIONS: Rates of undetectable PSA levels with testosterone recovery were similar between arms, suggesting that increased androgen suppression with AAP and androgen deprivation therapy (ADT) is unlikely to eradicate recurrent disease compared with ADT alone. PATIENT SUMMARY: We evaluated the use of abiraterone acetate plus prednisone (AAP) and androgen deprivation therapy (ADT), AAP alone, or ADT alone in men with biochemically recurrent, nonmetastatic prostate cancer. While more men who received the combination had an undetectable prostate-specific antigen (PSA) level at 8 mo on treatment, once men came off treatment and testosterone level rose, there was no difference in the rates of undetectable PSA levels. This suggests that the combination is not able to eradicate disease any better than ADT alone.

KEYNOTE-641: a Phase III study of pembrolizumab plus enzalutamide for metastatic castration-resistant prostate cancer.

Current treatment options for men with metastatic castration-resistant prostate cancer (mCRPC) are noncurative, and median survival upon development of mCRPC is approximately 3 years. The novel hormonal agent enzalutamide has an established role in the mCRPC treatment paradigm, and emerging evidence suggests potential synergism with enzalutamide and the PD-1 inhibitor pembrolizumab in men with mCRPC. Here, we describe the design and rationale for the multicenter, randomized, double-blind, Phase III KEYNOTE-641 study, which will be conducted to compare the efficacy and safety of pembrolizumab plus enzalutamide with that of enzalutamide plus placebo in mCRPC. Clinical trial registration: NCT03834493 (ClinicalTrials.gov).

Niraparib with androgen receptor-axis-targeted therapy in patients with metastatic castration-resistant prostate cancer: safety and pharmacokinetic results from a phase 1b study (BEDIVERE).

PURPOSE: To assess the safety and pharmacokinetics and determine the recommended phase 2 dose (RP2D) of niraparib with apalutamide or abiraterone acetate plus prednisone (AAP) in patients with metastatic castration-resistant prostate cancer (mCRPC). METHODS: BEDIVERE was a multicenter, open-label, phase 1b study of niraparib 200 or 300 mg/day with apalutamide 240 mg or AAP (abiraterone acetate 1000 mg; prednisone 10 mg). Patients with mCRPC were previously treated with ≥ 2 lines of systemic therapy, including ≥ 1 androgen receptor-axis-targeted therapy for prostate cancer. RESULTS: Thirty-three patients were enrolled (niraparib-apalutamide, 6; niraparib-AAP, 27). No dose-limiting toxicities (DLTs) were reported when combinations included niraparib 200 mg; five patients receiving niraparib 300 mg experienced DLTs [niraparib-apalutamide, 2/3 patients (66.7%); niraparib-AAP, 3/8 patients (37.5%)]. Although data are limited, niraparib exposures were lower when given with apalutamide compared with historical niraparib monotherapy exposures in patients with solid tumors. Because of the higher incidence of DLTs, the niraparib-apalutamide combination and niraparib 300 mg combination with AAP were not further evaluated. Niraparib 200 mg was selected as the RP2D with AAP. Of 19 patients receiving niraparib 200 mg with AAP, 12 (63.2%) had grade 3/4 treatment-emergent adverse events, the most common being thrombocytopenia (26.3%) and hypertension (21.1%). Five patients (26.3%) had adverse events leading to treatment discontinuation. CONCLUSIONS: These results support the choice of niraparib 200 mg as the RP2D with AAP. The niraparib-AAP combination was tolerable in patients with mCRPC, with no new safety signals. An ongoing phase 3 study is further assessing this combination in patients with mCRPC. TRIAL REGISTRATION NO: NCT02924766 (ClinicalTrials.gov).

Next-Generation Androgen Receptor-Signaling Inhibitors for Prostate Cancer: Considerations for Older Patients.

Prostate cancer is common, particularly in older patients, as the risk of getting prostate cancer increases with age. Cancer therapy brings unique challenges in older patients, as this population is vulnerable to many side effects and drug interactions, and they have varying degrees of frailty, which may limit the use of these therapies. The US FDA has recently approved several novel next-generation hormonal therapies for patients with various stages of prostate cancer, giving patients more treatment options. These therapies (e.g., apalutamide, enzalutamide, darolutamide, and abiraterone) have unique side effects that the practitioner must consider when evaluating therapeutic treatments in any patient, and these side effects also affect older patients differently. Here, we review the mechanism of action and metabolism of the next-generation hormonal therapies; report efficacy and safety data from trials of these agents in non-metastatic castration-resistant prostate cancer, metastatic hormone-sensitive prostate cancer, and metastatic castration-resistant prostate cancer; and discuss the intricacies of treating older men with prostate cancer. Key takeaways include the fact that enzalutamide and apalutamide may increase the risk of falls and fractures in older patients. Abiraterone requires the concurrent use of low-dose glucocorticoids, which can lead to side effects in older patients. Lastly, drug-drug interactions should be considered in older patients using multiple medications.

Apalutamide and Overall Survival in Prostate Cancer.

BACKGROUND: The phase 3 SPARTAN study evaluated apalutamide versus placebo in patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) and prostate-specific antigen doubling time of ≤10 mo. At primary analysis, apalutamide improved median metastasis-free survival (MFS) by 2 yr and overall survival (OS) data were immature. OBJECTIVE: We report the prespecified event-driven final analysis for OS. DESIGN, SETTING, AND PARTICIPANTS: A total of 1207 patients with nmCRPC (diagnosed by conventional imaging) were randomised 2:1 to apalutamide (240mg/d) or placebo, plus on-going androgen deprivation therapy. After MFS was met and the study was unblinded, 76 (19%) patients still receiving placebo crossed over to apalutamide. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: OS and time to cytotoxic chemotherapy (TTChemo) were analysed by group-sequential testing with O'Brien-Fleming-type alpha spending function. RESULTS AND LIMITATIONS: At median 52-mo follow-up, 428 deaths had occurred. The median treatment duration was 32.9 mo for apalutamide group and 11.5 mo for placebo group. Median OS was markedly longer with apalutamide versus placebo, reaching prespecified statistical significance (73.9 vs 59.9 mo, hazard ratio [HR]: 0.78 [95% confidence interval {CI}, 0.64-0.96]; p=0.016). Apalutamide also lengthened TTChemo versus placebo (HR: 0.63 [95% CI, 0.49-0.81]; p=0.0002). Discontinuation rates in apalutamide and placebo groups due to progressive disease were 43% and 74%, and due to adverse events 15% and 8.4%, respectively. Subsequent life-prolonging therapy was received by 371 (46%) patients in the apalutamide arm and by 338 (84%) patients in the placebo arm including 59 patients who received apalutamide after crossover. Safety was consistent with previous reports; when adverse events were adjusted for treatment exposure, rash had the greatest difference of incidence between the apalutamide and placebo groups. CONCLUSIONS: Extension of OS with apalutamide compared with placebo conferred impactful benefit in patients with nmCRPC. There was a 22% reduction in the hazard of death in the apalutamide group despite 19% crossover (placebo to apalutamide) and higher rates of subsequent therapy in the placebo group. PATIENT SUMMARY: With data presented herein, all primary and secondary study end points of SPARTAN were met; findings demonstrate the value of apalutamide as a treatment option for nonmetastatic castration-resistant prostate cancer.

Practical Considerations and Challenges for Germline Genetic Testing in Patients With Prostate Cancer: Recommendations From the Germline Genetics Working Group of the PCCTC.

Germline genetic testing is now routinely recommended for patients with prostate cancer (PCa) because of expanded guidelines and options for targeted treatments. However, integrating genetic testing into oncology and urology clinical workflows remains a challenge because of the increased number of patients with PCa requiring testing and the limited access to genetics providers. This suggests a critical unmet need for genetic services outside of historical models. This review addresses current guidelines, considerations, and challenges for PCa genetic testing and offers a practical guide for genetic counseling and testing delivery, with solutions to help address potential barriers and challenges for both providers and patients. As genetic and genomic testing become integral to PCa care, developing standardized systems for implementation in the clinic is essential for delivering precision oncology to patients with PCa and realizing the full scope and impact of genetic testing.

Leveraging Veterans Health Administration Clinical and Research Resources to Accelerate Discovery and Testing in Precision Oncology.

OBJECTIVE: The promise of precision oncology, which is the ability to choose a treatment specific to the characteristics of the tumor, has arrived. There are targeted therapies based on tumor mutations in multiple cancer types, both approved and in development. The US Department of Veterans Affairs (VA) has embraced precision oncology for the treatment of patients with prostate cancer. OBSERVATIONS: This article focuses on the efforts to bring precision oncology treatments and trials to veterans with prostate cancer through the Precision Oncology Program for Cancer of Prostate (POPCaP) Centers of Excellence (COE) and the clinical trials consortium inside POPCaP, Prostate Cancer Analysis for Therapy CHoice (PATCH). Through POPCaP, VA has analyzed hundreds of prostate cancer tumors to identify mutations and develop treatment plans for veterans with prostate cancer. PATCH will leverage the genetic data and prostate cancer expertise of POPCaP COEs to develop clinical trials for veterans that take a precision oncology approach to care. CONCLUSIONS: With its extensive resources and capabilities, VA has the ability to advance a precision oncology agenda that provides veterans with the highest standard of care. It has built upon many key elements in clinical, technological and scientific fields of study that would challenge most other health care systems given the extensive costs involved.

Phase II Study of Ipilimumab in Men With Metastatic Prostate Cancer With an Incomplete Response to Androgen Deprivation Therapy.

Background: Phase 3 studies of immune checkpoint inhibitors have not shown a survival benefit in prostate cancer, but some patients have a profound anticancer response. Patients and Methods: We evaluated the efficacy of the CTLA-4 targeted agent, ipilimumab, in metastatic prostate cancer patients who had an incomplete biochemical response to initial androgen deprivation therapy (ADT) alone. Ten patients were enrolled, each treated with ipilimumab 10 mg/kg (every 3 weeks for up to 4 doses) with maintenance ipilimumab every 12 weeks for non-progressing patients. The primary endpoint was proportion of patients with an undetectable PSA. The total sample size was 30 patients, but there was an interim analysis planned at 10 for futility. If none of the 10 patients achieved an undetectable PSA, the study would be halted. Results: The study was halted at the interim analysis as none of the 10 patients achieved the primary endpoint, but 30% of patients demonstrated a >50% reduction in PSA, with one patient achieving a >90% reduction in PSA. Peripheral blood mononuclear cells (PBMC) examined by mass cytometry showed that patients with clinical responses had an increase in effector memory T-cell subsets as well as an increase in T-cell expression of T-bet, suggesting induction of a Th1 response. Conclusions: This study provides further evidence that ipilimumab has activity in some patients with prostate cancer and provides further rationale for the development of future studies aimed at identifying a subset of patients with CPRC that are more likely to derive a benefit from treatment with ipilimumab. Implications for Practice: There is insufficient evidence to use ipilimumab in prostate cancer in routine practice. Trial Registration: ClinicalTrials.gov, NCT01498978. Registered 26 December 2011. https://www.clinicaltrials.gov/ct2/show/NCT01498978?term=julie+graff&rank=3.

Immunotherapy in Prostate Cancer.

Immunotherapy encompasses a wide range of therapies to engage the immune system to target malignancies. In recent years, immunotherapy has made a major impact on treatment of metastatic cancer and has altered standard of care for many tumor types. However, predicting and understanding responses across tumor types has been challenging. While some metastatic cancers have shown dramatic responses to immunotherapy, such as melanoma, lung cancer, and renal cell carcinoma, prostate cancer has generally failed to show a significant response. However, small series of prostate cancer patients have shown impressive responses to cellular and immunotherapy. This review summarizes the current data for immunotherapy's use in prostate cancer, as well as how currently available data might help predict patient responses to immunotherapy. Specifically, we will review vaccine-based therapies, immune checkpoint inhibitors, and future directions that are actively being explored.

A phase II single-arm study of pembrolizumab with enzalutamide in men with metastatic castration-resistant prostate cancer progressing on enzalutamide alone.

BACKGROUND: Checkpoint inhibitors can induce profound anticancer responses, but programmed cell death protein-1 (PD-1) inhibition monotherapy has shown minimal activity in prostate cancer. A published report showed that men with prostate cancer who were resistant to the second-generation androgen receptor inhibitor enzalutamide had increased programmed death-ligand 1 (PD-L1) expression on circulating antigen-presenting cells. We hypothesized that the addition of PD-1 inhibition in these patients could induce a meaningful cancer response. METHODS: We evaluated enzalutamide plus the PD-1 inhibitor pembrolizumab in a single-arm phase II study of 28 men with metastatic castration-resistant prostate cancer (mprogressing on enzalutamide alone. Pembrolizumab 200 mg intravenous was given every 3 weeks for four doses with enzalutamide. The primary endpoint was prostate-specific antigen (PSA) decline of ≥50%. Secondary endpoints were objective response, PSA progression-free survival (PFS), time to subsequent treatment, and time to death. Baseline tumor biopsies were obtained when feasible, and samples were sequenced and evaluated for the expression of PD-L1, microsatellite instability (MSI), mutational and neoepitope burdens. RESULTS: Five (18%) of 28 patients had a PSA decline of ≥50%. Three (25%) of 12 patients with measurable disease at baseline achieved an objective response. Of the five responders, two continue with PSA and radiographic response after 39.3 and 37.8 months. For the entire cohort, median follow-up was 37 months, and median PSA PFS time was 3.8 months (95% CI: 2.8 to 9.9 months). Time to subsequent treatment was 7.21 months (95% CI: 5.1 to 11.1 months). Median overall survival for all patients was 21.9 months (95% CI: 14.7 to 28 .4 months), versus 41.7 months (95% CI: 22.16 to not reached (NR)) in the responders. Of the three responders with baseline biopsies, one had MSI high disease with mutations consistent with DNA-repair defects. None had detectable PD-L1 expression. CONCLUSIONS: Pembrolizumab has activity in mCRPC when added to enzalutamide. Responses were deep and durable and did not require tumor PD-L1 expression or DNA-repair defects. TRIAL REGISTRATION NUMBER: clinicaltrials.gov (NCT02312557).