Characterization of structural, biochemical, pharmacokinetic, and pharmacodynamic properties of the LSD1 inhibitor bomedemstat in preclinical models.

INTRODUCTION: Lysine-specific demethylase 1 (LSD1) is emerging as a critical mediator of tumor progression in metastatic castration-resistant prostate cancer (mCRPC). Neuroendocrine prostate cancer (NEPC) is increasingly recognized as an adaptive mechanism of resistance in mCRPC patients failing androgen receptor axis-targeted therapies. Safe and effective LSD1 inhibitors are necessary to determine antitumor response in prostate cancer models. For this reason, we characterize the LSD1 inhibitor bomedemstat to assess its clinical potential in NEPC as well as other mCRPC pathological subtypes. METHODS: Bomedemstat was characterized via crystallization, flavine adenine dinucleotide spectrophotometry, and enzyme kinetics. On-target effects were assessed in relevant prostate cancer cell models by measuring proliferation and H3K4 methylation using western blot analysis. In vivo, pharmacokinetic (PK) and pharmacodynamic (PD) profiles of bomedemstat are also described. RESULTS: Structural, biochemical, and PK/PD properties of bomedemstat, an irreversible, orally-bioavailable inhibitor of LSD1 are reported. Our data demonstrate bomedemstat has >2500-fold greater specificity for LSD1 over monoamine oxidase (MAO)-A and -B. Bomedemstat also demonstrates activity against several models of advanced CRPC, including NEPC patient-derived xenografts. Significant intra-tumoral accumulation of orally-administered bomedemstat is measured with micromolar levels achieved in vivo (1.2 ± 0.45 µM at the 7.5 mg/kg dose and 3.76 ± 0.43 µM at the 15 mg/kg dose). Daily oral dosing of bomedemstat at 40 mg/kg/day is well-tolerated, with on-target thrombocytopenia observed that is rapidly reversible following treatment cessation. CONCLUSIONS: Bomedemstat provides enhanced specificity against LSD1, as revealed by structural and biochemical data. PK/PD data display an overall safety profile with manageable side effects resulting from LSD1 inhibition using bomedemstat in preclinical models. Altogether, our results support clinical testing of bomedemstat in the setting of mCRPC.

Patient-reported Quality of Life and Survival Outcomes in Prostate Cancer: Analysis of the ECOG-ACRIN E3805 Chemohormonal Androgen Ablation Randomized Trial (CHAARTED).

BACKGROUND: Chemohormonal therapy with androgen deprivation therapy and docetaxel (ADT + D) improves overall survival (OS) and quality of life (QOL) at 12 mo versus androgen deprivation therapy (ADT) alone in men with metastatic hormone-sensitive prostate cancer (mHSPC). However, the prognostic role of QOL is unknown in this population. OBJECTIVE: To study the relationship between QOL, disease characteristics, and OS in men with mHSPC. DESIGN, SETTING, AND PARTICIPANTS: In this exploratory post hoc analysis, 790 patients with mHSPC completed the QOL instruments Functional Assessment of Cancer Therapy-Prostate (FACT-P), Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), and Brief Pain Inventory (BPI). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Log-rank test and Cox proportional hazard models tested the association between QOL and OS by clinical and disease characteristics. RESULTS AND LIMITATIONS: Baseline higher FACT-P trended toward improved survival after accounting for clinical variables (hazard ratio [HR] 0.80 [0.62, 1.04], p = 0.09), while higher 3-mo FACT-P was independently associated with better survival (HR 0.76 [0.58, 1.0], p = 0.05). Patients with the poorest QOL (bottom quartile) at baseline and 3 mo had longer survival if they received ADT + D rather than ADT alone (median OS 45.2 vs 34.4 mo, HR 0.75 [0.53, 1.05], p = 0.09, and 48.3 vs 29.3 mo, HR 0.69 [0.48, 0.99], p = 0.05 respectively). In contrast, patients with the best QOL (top quartile) at baseline and 3 mo had comparable survival irrespective of whether or not docetaxel was added (median OS 72.1 vs 51.7 mo, HR 0.92 [0.63, 1.36], p = 0.69, and 69.9 vs 68.9 mo, HR 1.11 [0.73, 1.67], p = 0.63, respectively). Survival was linked with baseline FACIT-F (HR 0.76 [0.57, 1.0], p = 0.05), but not BPI (HR 0.98 [0.75, 1.28], p = 0.90). CONCLUSIONS: Three-month QOL had a stronger independent association with survival. The most symptomatic patients had longer survival with the addition of docetaxel; conversely, the least symptomatic patients did not appear to benefit. Consideration of QOL may enhance decision-making and patient selection when choosing chemohormonal treatment in mHSPC. PATIENT SUMMARY: Quality of life independently forecasted the survival of men with metastatic hormone-sensitive prostate cancer in the CHAARTED study. Close tracking of quality of life could help patients and clinicians make decisions about the appropriate treatment in this setting.

Randomized, Double-Blind Phase III Study of Pazopanib Versus Placebo in Patients With Metastatic Renal Cell Carcinoma Who Have No Evidence of Disease After Metastasectomy: ECOG-ACRIN E2810.

PURPOSE: Patients with no evidence of disease (NED) after metastasectomy for renal cell carcinoma are at high risk of recurrence. Pazopanib is an inhibitor of vascular endothelial growth factor receptor and other kinases that improves progression-free survival in patients with metastatic RCC (mRCC). We conducted a randomized, double-blind, placebo-controlled multicenter study to test whether pazopanib would improve disease-free survival (DFS) in patients with mRCC rendered NED after metastasectomy. PATIENTS AND METHODS: Patients with NED after metastasectomy were randomly assigned 1:1 to receive pazopanib 800 mg once daily versus placebo for 52 weeks. The study was designed to observe an improvement in DFS from 25% to 45% with pazopanib at 3 years, corresponding to 42% reduction in the DFS event rate. RESULTS: From August 2012 to July 2017, 129 patients were enrolled. The study was unblinded after 83 DFS events (92% information). The study did not meet its primary end point. An updated analysis at 60.5-month median follow-up from random assignment (95% CI, 59.3 to 71.0) showed that the 3-year DFS was 27.4% (95% CI, 17.9 to 41.7) for pazopanib and 21.9% (95% CI, 13.3 to 36.2) for placebo. Hazard ratio (HR) for DFS was 0.90 ([95% CI, 0.60 to 1.34]; Pone-sided = .29) in favor of pazopanib. Three-year overall survival (OS) was 81.9% (95% CI, 72.7 to 92.2) for pazopanib and 91.4% (95% CI, 84.4 to 98.9) for placebo. The HR for OS was 2.55 (95% CI, 1.23 to 5.27) in favor of placebo (Ptwo-sided = .012). Health-related quality-of-life measures deteriorated in the pazopanib group during the treatment period. CONCLUSION: Pazopanib did not improve DFS as the primary end point compared with blinded placebo in patients with mRCC with NED after metastasectomy. In addition, there was a concerning trend favoring placebo in OS.

Pharmacogenetic and clinical risk factors for bevacizumab-related gastrointestinal hemorrhage in prostate cancer patients treated on CALGB 90401 (Alliance).

The objective of this study was to discover clinical and pharmacogenetic factors associated with bevacizumab-related gastrointestinal hemorrhage in Cancer and Leukemia Group B (Alliance) 90401. Patients with metastatic castration-resistant prostate cancer received docetaxel and prednisone ± bevacizumab. Patients were genotyped using Illumina HumanHap610-Quad and assessed using cause-specific risk for association between single nucleotide polymorphisms (SNPs) and gastrointestinal hemorrhage. In 1008 patients, grade 2 or higher gastrointestinal hemorrhage occurred in 9.5% and 3.8% of bevacizumab (n = 503) and placebo (n = 505) treated patients, respectively. Bevacizumab (P < 0.001) and age (P = 0.002) were associated with gastrointestinal hemorrhage. In 616 genetically estimated Europeans (n = 314 bevacizumab and n = 302 placebo treated patients), grade 2 or higher gastrointestinal hemorrhage occurred in 9.6% and 2.0% of patients, respectively. One SNP (rs1478947; HR 6.26; 95% CI 3.19-12.28; P = 9.40 × 10-8) surpassed Bonferroni-corrected significance. Grade 2 or higher gastrointestinal hemorrhage rate was 33.3% and 6.2% in bevacizumab-treated patients with the AA/AG and GG genotypes, versus 2.9% and 1.9% in the placebo arm, respectively. Prospective validation of these findings and functional analyses are needed to better understand the genetic contribution to treatment-related gastrointestinal hemorrhage.

CRM1 regulates androgen receptor stability and impacts DNA repair pathways in prostate cancer, independent of the androgen receptor.

Among the known nuclear exportins, CRM1 is the most studied prototype. Dysregulation of CRM1 occurs in many cancers, hence, understanding the role of CRM1 in cancer can help in developing synergistic therapeutics. The study investigates how CRM1 affects prostate cancer growth and survival. It examines the role of CRM1 in regulating androgen receptor (AR) and DNA repair in prostate cancer. Our findings reveal that CRM1 influences AR mRNA and protein stability, leading to a loss of AR protein upon CRM1 inhibition. Furthermore, it highlights the involvement of HSP90 alpha, a known AR chaperone, in the CRM1-dependent regulation of AR protein stability. The combination of CRM1 inhibition with an HSP90 inhibitor demonstrates potent effects on decreasing prostate cancer cell growth and survival. The study further explores the influence of CRM1 on DNA repair proteins and proposes a strategy of combining CRM1 inhibitors with DNA repair pathway inhibitors to decrease prostate cancer growth. Overall, the findings suggest that CRM1 plays a crucial role in prostate cancer growth, and a combination of inhibitors targeting CRM1 and DNA repair pathways could be a promising therapeutic strategy.

Radiographic Progression-Free Survival and Clinical Progression-Free Survival as Potential Surrogates for Overall Survival in Men With Metastatic Hormone-Sensitive Prostate Cancer.

PURPOSE: Despite major increases in the longevity of men with metastatic hormone-sensitive prostate cancer (mHSPC), most men still die of prostate cancer. Phase III trials assessing new therapies in mHSPC with overall survival (OS) as the primary end point will take approximately a decade to complete. We investigated whether radiographic progression-free survival (rPFS) and clinical PFS (cPFS) are valid surrogates for OS in men with mHSPC and could potentially be used to expedite future phase III clinical trials. METHODS: We obtained individual patient data (IPD) from 9 eligible randomized trials comparing treatment regimens (different androgen deprivation therapy [ADT] strategies or ADT plus docetaxel in the control or research arms) in mHSPC. rPFS was defined as the time from random assignment to radiographic progression or death from any cause whichever occurred first; cPFS was defined as the time from random assignment to the date of radiographic progression, symptoms, initiation of new treatment, or death, whichever occurred first. We implemented a two-stage meta-analytic validation model where conditions of patient-level and trial-level surrogacy had to be met. We then computed the surrogate threshold effect (STE). RESULTS: IPD from 6,390 patients randomly assigned from 1994 to 2012 from 13 units were pooled for a stratified analysis. The median OS, rPFS, and cPFS were 4.3 (95% CI, 4.2 to 4.5), 2.4 (95% CI, 2.3 to 2.5), and 2.3 years (95% CI, 2.2 to 2.4), respectively. The STEs were 0.80 and 0.81 for rPFS and cPFS end points, respectively. CONCLUSION: Both rPFS and cPFS appear to be promising surrogate end points for OS. The STE of 0.80 or higher makes it viable for either rPFS or cPFS to be used as the primary end point that is surrogate for OS in phase III mHSPC trials with testosterone suppression alone as the backbone therapy and would expedite trial conduct.

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.

The ENGAGE study: evaluation of a conversational virtual agent that provides tailored pre-test genetic education to cancer patients.

PURPOSE: Novel approaches are needed to ensure all patients with cancer have access to quality genetic education before genetic testing to enable informed treatment decisions. The purpose of this study was to test the use of an artificial intelligence (AI) intervention for the delivery of genetic education by non-genetic providers to patients with cancer undergoing active treatment. METHODS: A conversational AI-based application was developed on the HealthFAX platform to provide tailored genetic education to patients with cancer and tested at Johns Hopkins Hospital between April 2021 and Feb 2022. Patients' responses around the adoption, use, and experience of the AI application were assessed. RESULTS: Out of 64 individuals who consented to the study, 51 accessed the tool. The responding participants had a mean age of 61 years (ranging from 30-90 years) with 39 individuals undergoing active treatment for breast cancer and 12 for advanced prostate cancer. All patients chose to complete the tool at home. The median time between study enrollment and AI application initiation was 1 day, and the median time to complete the application was 24 min. All participants in their survey responses felt that the tool was secure, easy to use, liked the convenience of viewing it at home, and felt it provided valuable information. Eighteen percent of participants viewed the application with a family member. Ninety-eight percent of the participants completed their genetic education prior to receiving their test results. In 16%, a pathogenic variant was identified. CONCLUSIONS: The 51 patients who adopted the AI application were highly satisfied with its usability and convenience. Our results support the continued evaluation of this cost-effective AI application in a large-scale study. IMPLICATIONS FOR CANCER SURVIVORS: Tailored pre-test genetic education can be successfully delivered to patients with cancer undergoing active treatment via an AI application at their convenience.

PrECOG PrE0807: A Phase 1b Feasibility Trial of Neoadjuvant Nivolumab Without and with Lirilumab in Patients with Muscle-invasive Bladder Cancer Ineligible for or Refusing Cisplatin-based Neoadjuvant Chemotherapy.

BACKGROUND AND OBJECTIVE: Neoadjuvant cisplatin-based chemotherapy prior to radical cystectomy (RC) improves overall survival (OS) in muscle-invasive bladder cancer (MIBC). However, many patients are cisplatin ineligible; therefore, new treatment options are needed. Nivolumab without/with lirilumab prior to RC was investigated in cisplatin-ineligible patients in this phase 1b trial (NCT03532451) to determine its safety/feasibility. METHODS: Patients with localized MIBC received two doses of nivolumab (480 mg) alone (cohort 1) or with lirilumab (240 mg; cohort 2) prior to RC. Cohorts were enrolled sequentially. The key eligibility criteria were cT2-4aN0-1M0 stage and cisplatin ineligibility/refusal. The primary endpoint was the rate of grade (G) ≥3 treatment-related adverse events (TRAEs) as per Common Terminology Criteria for Adverse Events version 5.0. The key secondary endpoints included the proportion of patients who underwent RC >6 wk after the last dose, CD8+ T-cell density change between pretreatment transurethral resection of bladder tumor (TURBT) and post-treatment RC, ypT0N0, 6 wk. In cohorts 1 and 2, ypT0N0 rates for patients with MIBC and RC were 17% and 21%,

Phase I Study of Entinostat, Atezolizumab, Carboplatin, and Etoposide in Previously Untreated Extensive-Stage Small Cell Lung Cancer, ETCTN 10399.

BACKGROUND: CREBBP and EP300 mutations occur at a frequency of 15% and 13%, respectively, in small cell lung cancer (SCLC), and preclinical models demonstrated susceptibility to targeting with HDAC inhibitors. METHODS: Patients with treatment-naïve extensive-stage SCLC, ECOG ≤2 were enrolled and treated with entinostat orally weekly (4 dose levels, DL) in combination with standard dose carboplatin, etoposide, and atezolizumab. Cohort allocation was determined by Bayesian optimal interval (BOIN) design targeting an MTD with a DLT rate of 20%. RESULTS: Three patients were enrolled and treated at DL1 with entinostat 2 mg. Patients were aged 69-83; 2 male, 1 female; 2 were ECOG 1, and 1 was ECOG 0. The most common adverse events (AEs) were anemia (3), neutropenia (3), thrombocytopenia (2), leukopenia (2), and hypocalcemia (2). Two experienced DLTs during cycle 1: (1) grade (Gr) 4 febrile neutropenia, and (1) Gr 5 sepsis. BOIN design required stopping accrual to DL1, and the trial was closed to further accrual. Entinostat and atezolizumab pharmacokinetics were both comparable to historical controls. CONCLUSION: Addition of entinostat to atezolizumab, carboplatin, and etoposide is unsafe and resulted in early onset and severe neutropenia, thrombocytopenia. Further exploration of entinostat with carboplatin, etoposide, and atezolizumab should not be explored. (ClinicalTrials.gov Identifier: NCT04631029).

A First-in-human, Dose-escalation Study of the Methionine Aminopeptidase 2 Inhibitor M8891 in Patients with Advanced Solid Tumors.

Methionine aminopeptidase 2 (MetAP2) is essential to endothelial cell growth and proliferation during tumor angiogenesis. M8891 is a novel orally bioavailable, potent, selective, reversible MetAP2 inhibitor with antiangiogenic and antitumor activity in preclinical studies. The safety, tolerability, pharmacokinetics, and pharmacodynamics of M8891 monotherapy were assessed in a phase I, first-in-human, multicenter, open-label, single-arm, dose-escalation study (NCT03138538). Patients with advanced solid tumors received 7-80 mg M8891 once daily in 21-day cycles. The primary endpoint was dose-limiting toxicity (DLT) during cycle 1, with the aim to determine the maximum tolerated dose (MTD). Twenty-seven patients were enrolled across six dose levels. Two DLTs (platelet count decrease) were reported, one each at 60 and 80 mg/once daily M8891, resolving after treatment discontinuation. MTD was not determined. The most common treatment-emergent adverse event was platelet count decrease. M8891 plasma concentration showed dose-linear increase up to 35 mg and low-to-moderate variability; dose-dependent tumor accumulation of methionylated elongation factor 1α, a MetAP2 substrate, was observed, demonstrating MetAP2 inhibition. Pharmacokinetic/pharmacodynamic response data showed that preclinically defined target levels required for in vivo efficacy were achieved at safe, tolerated doses. Seven patients (25.9%) had stable disease for 42-123 days. We conclude that M8891 demonstrates a manageable safety profile, with dose-proportional exposure and low-to-moderate interpatient variability at target pharmacokinetic/pharmacodynamic levels at ≤35 mg M8891 once daily. On the basis of the data, 35 mg M8891 once daily is the recommended phase II dose for M8891 monotherapy. This study forms the basis for future development of M8891 in monotherapy and combination studies. Significance: M8891 represents a novel class of reversible MetAP2 inhibitors and has demonstrated preclinical antitumor activity. This dose-escalation study assessed M8891 treatment for patients with advanced solid tumors. M8891 demonstrated favorable pharmacokinetics, tumoral target engagement, and a manageable safety profile, and thus represents a novel antitumor strategy warranting further clinical studies.

Results From a Randomized Phase II Trial of Sunitinib and Gemcitabine or Sunitinib in Advanced Renal Cell Carcinoma with Sarcomatoid Features: ECOG-ACRIN E1808.

INTRODUCTION: Sarcomatoid renal cancer (sRCC) patients have poor outcomes. EA1808 evaluated sunitinib and gemcitabine (SG) and sunitinib alone (S) in sRCC in a randomized cooperative group phase II trial (NCT01164228). PATIENTS AND METHODS: Pts were aggregated 1:1 to SG (45 pts) or S (40 pts) using a 2-stage design. sRCC pts with ≤ 1 prior nonvascular endothelial growth factor tyrosine kinase inhibitor were stratified into prognostic groups: good (clear cell, < 20% sarcomatoid, PS 0), intermediate (20%-50% sarcomatoid, PS 0), and poor (nonclear cell or > 50% sarcomatoid or PS 1). The primary endpoint was response rate (RR). For SG, the null RR was 15% and a 30% RR was of interest. For S, a 20% RR was of interest vs. a 5% null rate. Secondary endpoints were progression-free survival, overall survival, and safety. RESULTS: Both arms met protocol criteria for stage 2 of accrual. A total of 47 pts were randomized to SG and 40 to S. The SG arm had 9 of 45 evaluable patient responses (RR of 20%; CI = [13%-31%]) not meeting the predetermined threshold for success. The sunitinib arm met its endpoint with 6/37 (RR of 16%; CI = [9%-27%]) evaluable responses. Grade ≥ 3 events were experienced by 36 in the SG arm and 17 in the sunitinib arm CONCLUSIONS: EA1808 was the largest and first randomized cytotoxic trial for sarcomatoid RCC. Sunitinib alone but not the SG met the preset threshold of success. Cytotoxic chemotherapy is only useful in limited clinical scenarios for sRCC.

External Validation of a Prognostic Model of Overall Survival in Men With Chemotherapy-Naïve Metastatic Castration-Resistant Prostate Cancer.

PURPOSE: We have previously developed and externally validated a prognostic model of overall survival (OS) in men with metastatic, castration-resistant prostate cancer (mCRPC) treated with docetaxel. We sought to externally validate this model in a broader group of men with docetaxel-naïve mCRPC and in specific subgroups (White, Black, Asian patients, different age groups, and specific treatments) and to classify patients into validated two and three prognostic risk groupings on the basis of the model. METHODS: Data from 8,083 docetaxel-naïve mCRPC men randomly assigned on seven phase III trials were used to validate the prognostic model of OS. We assessed the predictive performance of the model by computing the time-dependent area under the receiver operating characteristic curve (tAUC) and validated the two-risk (low and high) and three-risk prognostic groups (low, intermediate, and high). RESULTS: The tAUC was 0.74 (95% CI, 0.73 to 0.75), and when adjusting for the first-line androgen receptor (AR) inhibitor trial status, the tAUC was 0.75 (95% CI, 0.74 to 0.76). Similar results were observed by the different racial, age, and treatment subgroups. In patients enrolled on first-line AR inhibitor trials, the median OS (months) in the low-, intermediate-, and high-prognostic risk groups were 43.3 (95% CI, 40.7 to 45.8), 27.7 (95% CI, 25.8 to 31.3), and 15.4 (95% CI, 14.0 to 17.9), respectively. Compared with the low-risk prognostic group, the hazard ratios for the high- and intermediate-risk groups were 4.3 (95% CI, 3.6 to 5.1; P < .0001) and 1.9 (95% CI, 1.7 to 2.1; P < .0001). CONCLUSION: This prognostic model for OS in docetaxel-naïve men with mCRPC has been validated using data from seven trials and yields similar results overall and across race, age, and different treatment classes. The prognostic risk groups are robust and can be used to identify groups of patients for enrichment designs and for stratification in randomized clinical trials.

Role of bromodomain and extraterminal (BET) proteins in prostate cancer.

INTRODUCTION: The bromodomain and extraterminal (BET) family of proteins are epigenetic readers of acetylated histones and are critical activators of oncogenic networks across many cancers. Therapeutic targeting of BET proteins has been an attractive area of clinical development for metastatic castration-resistant prostate cancer. In recent years, many structurally diverse BET inhibitors have been discovered and tested. Preclinical studies have demonstrated significant antiproliferative activity of BET inhibitors against prostate cancer. However, their clinical success as monotherapies has been limited by treatment-associated toxicities, primary and acquired drug resistance, and a lack of predictive biomarkers of benefit. AREAS COVERED: This review provides an overview of advancements in BET inhibitor design, preclinical research, and conclusions from clinical trials in prostate cancer. We speculate on incorporating BET inhibitors into combination regimens with other agents to improve the therapeutic index of BET inhibition in treating prostate cancer. EXPERT OPINION: The therapeutic potential of BET inhibitors for prostate cancer has been demonstrated in preclinical studies. However, further research is needed to identify biomarkers that can predict sensitivity to BET inhibitors and to develop novel, highly selective inhibitors to reduce toxicities. Finally, BET inhibitors are likely to hold the most clinical potential in combination with other agents.

Addressing multilevel barriers to clinical trial participation among Black and White men with prostate cancer through the PACCT study.

BACKGROUND: Cancer clinical trial participation is low and inequitable. Partnering Around Cancer Clinical Trials (PACCT) addressed systemic and interpersonal barriers through an observational study of eligibility and an intervention to improve patient-physician communication and trial invitation rates. METHODS: Physicians at two comprehensive cancer centers and Black and White men with prostate cancer participated. Patients were followed for 2 years to determine whether they became potentially eligible for an available therapeutic trial. Potentially eligible patients were randomized to receive a trials-focused Question Prompt List or usual care. Patient-physician interactions were video-recorded. Outcomes included communication quality and trial invitation rates. Descriptive analyses assessed associations between sociodemographic characteristics and eligibility and effects of the intervention on outcomes. RESULTS: Only 44 (22.1%) of participating patients (n = 199) became potentially eligible for an available clinical trial. Patients with higher incomes were more often eligible (>$80,000 vs. <$40,000, adjusted OR = 6.06 [SD, 1.97]; $40,000-$79,000 vs. <$40,000, adjusted OR = 4.40 [SD, 1.81]). Among eligible patients randomized to the intervention (n = 19) or usual care (n = 25), Black patients randomized to the intervention reported participating more actively than usual care patients, while White intervention patients reported participating less actively (difference, 0.41 vs. -0.34). Intervention patients received more trial invitations than usual care patients (73.7% vs. 60.0%); this effect was greater for Black (80.0% vs. 30.0%) than White patients (80.0% vs. 66.7%). CONCLUSIONS: Findings suggest the greatest enrollment barrier is eligibility for an available trial, but a communication intervention can improve communication quality and trial invitation rates, especially for eligible Black patients.

Olaparib Efficacy in Patients with Metastatic Castration-resistant Prostate Cancer and BRCA1, BRCA2, or ATM Alterations Identified by Testing Circulating Tumor DNA.

PURPOSE: The phase III PROfound study (NCT02987543) evaluated olaparib versus abiraterone or enzalutamide (control) in metastatic castration-resistant prostate cancer (mCRPC) with tumor homologous recombination repair (HRR) gene alterations. We present exploratory analyses on the use of circulating tumor DNA (ctDNA) testing as an additional method to identify patients with mCRPC with HRR gene alterations who may be eligible for olaparib treatment. PATIENTS AND METHODS: Plasma samples collected during screening in PROfound were retrospectively sequenced using the FoundationOne®Liquid CDx test for BRCA1, BRCA2 (BRCA), and ATM alterations in ctDNA. Only patients from Cohort A (BRCA/ATM alteration positive by tissue testing) were evaluated. We compared clinical outcomes, including radiographic progression-free survival (rPFS) between the ctDNA subgroup and Cohort A. RESULTS: Of the 181 (73.9%) Cohort A patients who gave consent for plasma sample ctDNA testing, 139 (76.8%) yielded a result and BRCA/ATM alterations were identified in 111 (79.9%). Of these, 73 patients received olaparib and 38 received control. Patients' baseline demographics and characteristics, and the prevalence of HRR alterations were comparable with the Cohort A intention-to-treat (ITT) population. rPFS was longer in the olaparib group versus control [median 7.4 vs. 3.5 months; hazard ratio (HR), 0.33; 95% confidence interval (CI), 0.21-0.53; nominal P < 0.0001], which is consistent with Cohort A ITT population (HR, 0.34; 95% CI, 0.25-0.47). CONCLUSIONS: When tumor tissue testing is not feasible or has failed, ctDNA testing may be a suitable alternative to identify patients with mCRPC carrying BRCA/ATM alterations who may benefit from olaparib treatment.

FRACTION-RCC: nivolumab plus ipilimumab for advanced renal cell carcinoma after progression on immuno-oncology therapy.

BACKGROUND: The role and sequencing of combination immuno-oncology (IO) therapy following progression on or after first-line IO therapy has not been well-established. The Fast Real-time Assessment of Combination Therapies in Immuno-ONcology (FRACTION) program is an open-label, phase 2 platform trial designed to evaluate multiple IO combinations in patients with advanced renal cell carcinoma (aRCC) who progressed during or after prior IO therapy. Here, we describe the results for patients treated with nivolumab plus ipilimumab. For enrollment in track 2 (reported here), patients with histologically confirmed clear cell aRCC, Karnofsky performance status ≥70%, and life expectancy ≥3 months who had previously progressed after IO (anti-programmed death 1 (PD-1), anti-programmed death-ligand 1 (PD-L1), or anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4)) therapy were eligible. Previous treatment with anti-CTLA-4 therapy plus anti-PD-1/PD-L1 therapy precluded eligibility for enrollment in the nivolumab plus ipilimumab arm. Patients were treated with nivolumab 3 mg/kg plus ipilimumab 1 mg/kg every 3 weeks for four doses, followed by nivolumab 480 mg every 4 weeks for up to 2 years or until progression, toxicity, or protocol-specified discontinuation. The primary outcome measures were objective response rate (ORR), duration of response (DOR), and progression-free survival (PFS) rate at 24 weeks. Secondary outcomes were safety and tolerability up to 2 years. Overall survival (OS) was a tertiary/exploratory endpoint. Overall, 46 patients were included with a median follow-up of 33.8 months. The ORR was 17.4% (95% CI, 7.8 to 31.4) with eight (17.4%) patients achieving partial response. Stable disease was achieved in 19 (41.3%) patients, while 14 (30.4%) had progressive disease. Median DOR (range) was 16.4 (2.1+ to 27.0+) months. The PFS rate at 24 weeks was 43.2%, and median OS was 23.8 (95% CI, 13.2 to not reached) months. Grade 3-4 immune-mediated adverse events were reported in seven (15.2%) patients. No treatment-related deaths were reported. Patients with aRCC treated with nivolumab plus ipilimumab may derive durable clinical benefit after progression on previous IO therapies, including heavily pretreated patients, with a manageable safety profile that was consistent with previously published safety outcomes. These outcomes contribute to the knowledge of optimal sequencing of IO therapies for patients with aRCC with high unmet needs. TRIAL REGISTRATION NUMBER: NCT02996110.

Increased MYBL2 expression in aggressive hormone-sensitive prostate cancer.

Loss of the histone demethylase KDM5D (lysine-specific demethylase 5D) leads to in vitro resistance of prostate cancer cells to androgen deprivation therapy (ADT) with and without docetaxel. We aimed to define downstream drivers of the KDM5D effect. Using chromatin immunoprecipitation sequencing (ChIP-seq) of the LNCaP cell line (androgen-sensitive human prostate adenocarcinoma) with and without silenced KDM5D, MYBL2-binding sites were analyzed. Associations between MYBL2 mRNA expression and clinical outcomes were assessed in cohorts of men with localized and metastatic hormone-sensitive prostate cancer. In vitro assays with silencing and overexpression of MYBL2 and KDM5D in androgen receptor (AR)-positive hormone-sensitive prostate cancer cell lines, LNCaP and LAPC4, were used to assess their influence on cellular proliferation, apoptosis, and cell cycle distribution, as well as sensitivity to androgen deprivation, docetaxel, and cabazitaxel. We found that silencing KDM5D increased histone H3 lysine K4 (H3K4) trimethylation and increased MYBL2 expression. KDM5D and MYBL2 were negatively correlated with some but not all clinical samples. Higher MYBL2 expression was associated with a higher rate of relapse in localized disease and poorer overall survival in men with metastatic disease in the CHAARTED trial. Lower MYBL2 levels enhanced LNCaP and LAPC4 sensitivity to androgen deprivation and taxanes. In vitro, modifications of KDM5D and MYBL2 altered cell cycle distribution and apoptosis in a cell line-specific manner. These results show that the transcription factor MYBL2 impacts in vitro hormone-sensitive prostate cancer sensitivity to androgen deprivation and taxanes, and lower levels are associated with better clinical outcomes in men with hormone-sensitive prostate cancer.