Study Of Enzalutamide Research Articles

A phase I/II study of enzalutamide in combination with indomethacin in men with castration-resistant prostate cancer (CRPC).

e17027 Background: Metastatic castration resistant prostate cancer (mCRPC) remains an incurable disease despite recent advances in therapy. In patients (pts) receiving the second-generation androgen receptor antagonist enzalutamide (enza), primary or adaptive resistance can occur due to upregulation of the steroidogenesis pathway, including aldo-keto reductase 1C3 (AKR1C3), which can also upregulate intratumoral androgen synthesis. Indomethacin, a non-steroidal anti-inflammatory drug and selective inhibitor of AKR1C3, demonstrates synergistic activity when combined with enza against enza-resistant CRPC in vitro and in vivo. We thus sought to study this combination in a clinical trial. Methods: This investigator-initiated Phase I/II trial enrolled pts with enza-naive mCRPC on androgen deprivation therapy. Prior abiraterone was allowed. Pts must have adequate organ function and ECOG performance status 0-2. In the phase I lead-in, a 3+3 dose de-escalation design was used to identify the recommended Phase II dose (RP2D) of indomethacin in combination with enza 160 mg oral (PO) once daily, after which a Phase II expansion proceeded. Pts continued treatment until disease progression or unacceptable toxicity. Co-primary endpoints were safety and PSA response, defined as 50% or more reduction from baseline. Secondary endpoints included overall response as determined by Prostate Cancer Working Group 2 criteria (PCWG2). Results: From 2017 - 2022, 26 pts were enrolled, with a median age of 71 (range 50-88), primarily white (n=16, 62%), median baseline PSA 19.45 (range 1.5-210), ECOG 1 (n=12, 46%), and most received prior abiraterone (n=24, 92%). In 6 pts enrolled to the phase I cohort, there were no grade 3 adverse events (AEs); RP2D of indomethacin was 50mg PO twice daily. All 26 pts were evaluable for safety and efficacy. Most common treatment-related AEs (n; %) were nausea (12; 46%), fatigue (11; 42%), diarrhea (8; 31%), hypertension (7; 27%), anorexia (6; 23%). Most common ≥ grade 3 treatment-related AEs were acute kidney injury (3; 12%), hypertension (3; 12%), and anemia (2; 8%). PSA response was observed in 8 pts (31%). By PCWG2, 14 pts (54%) experienced stable disease, while 10 pts (38%) had progressive disease. Conclusions: The combination of enza and indomethacin was safe, clinically feasible, and had clinical activity in pts with abiraterone-pretreated mCRPC. Further correlative studies are needed to identify pts who may benefit from AKR1C3 inhibition. Clinical trial information: NCT02935205 .

Molecular underpinnings of RB status as a biomarker of poor outcome in advanced prostate cancer.

189 Background: There is emergent and compelling evidence to support RB status as a biomarker in advanced prostate cancer. RB loss is strongly associated with poor progression-free, disease-specific, and overall survival in prostate cancer (PCa). Preclinical studies in PCa have revealed RB positive tumors are more responsive to CDK4/6 inhibitors. An ongoing randomized Phase IB/II study of enzalutamide with and without ribociclib in patients with metastatic castration-resistant, chemotherapy naïve PCa has become a pioneer trial to include a positive RB status as inclusion criteria in a PCa study (NCT02555189). Beyond CDK4/6 inhibitors, therapeutic agents that target tumor metabolism have been introduced in the clinic. Current data suggests that RB status may be crucial to understand and predict therapeutic response to these agents within tumors. Methods: The biological significance of RB loss was studied utilizing isogenic model systems and human tumor xenografts of castration resistant prostate cancer (CRPC) with and without RB deletion. The mechanism that drives aggressive tumor phenotypes was identified through comprehensive transcriptomic, cistromic, and metabolomic analysis. Novel functions of RB were identified and the response to clinically-relevant therapeutics was examined. Results: Exclusively in CRPC, RB loss results in significant rewiring of cancer cell metabolism. Functional investigation revealed a causative link between RB loss and antioxidant production sufficient to alter responsiveness to genomic insult and selected chemotherapeutics. Observed changes in response to therapeutic intervention were attributed to RB-dependent modulation of intracellular reactive oxygen species. Conclusions: RB loss is strongly associated with poor outcome in advanced PCa. Molecular investigation identified RB-dependent rewiring of cancer cell metabolism as a significant consequence of RB loss, sufficient to alter response in model systems to therapeutic strategies of clinical relevance. These studies significantly advance understanding of the means by which RB loss enhances lethal tumor phenotypes, and are of relevance for development of RB status as a clinically actionable biomarker.

Results from a phase Ib/II study of enzalutamide and metformin in men with castration resistant prostate cancer (CRPC).

5054 Background: Preclinical models have shown that autophagy is a cell survival mechanism to overcome treatment-induced stress and facilitate progression and resistance in CRPC. Metformin (met) demonstrates autophagy inhibition and resensitizes CRPC tumors to enzalutamide (enza) as a combination in in vitro models. A Phase Ib/II trial was conducted to evaluate the combination. Methods: Eligible patients (pts) had established CRPC, ECOG 0-2, adequate hematologic and organ function, and ≤ 2 prior treatments for CRPC. Major exclusion criteria included prior enza or met treatment, presence of brain metastases, history of DM2 or seizures. An initial cohort of 3 pts were treated with enza 160 mg PO daily and met 500 mg PO bid (DL1), with met dose escalated to 1000 mg PO bid (DL2) in subsequent 3 pts if dose-limiting toxicity (DLT) was observed in ≤1 pt in DL 1, and cycles of 28 days. Once primary objective of maximum tolerated dose (MTD) was established, additional pts were enrolled at MTD for a total of 24 evaluable pts. Secondary objectives of the study included PSA response and safety. Results: From 8/24/16-12/31/18, a total of 3 pts were enrolled to DL1, with no DLTs observed in that cohort, with an additional 21 enrolled to DL2; 12 remain on trial. Median age was 71, with 8/24 (33%) and 3/24 (12.5%) with prior docetaxel and abiraterone treatment, respectively. One DLT due to Grade 3 abdominal pain was observed at DL2 prior to establishing MTD. Grade 3 AEs observed in 1/24 (4%) of pts were diarrhea, fatigue, hypertension, lower GI bleed, myalgia; 2/24 (8%) had abdominal pain. One pt had Grade 4 hallucinations. Among pts who discontinued, 8 were discontinued for progression, 3 withdrew consent, and 1 experienced an SAE (seizure). Pts received median of 11 cycles (1-31) of treatment. PSA response ≥ 50% was observed in 19/24 (79%) pts. Conclusions: The combination of enzalutamide 160 mg PO daily and metformin 1000 mg PO bid is well-tolerated, and clinically active. Clinical trial information: NCT02339168.

Phase 1b/2 study of enzalutamide (ENZ) with LY3023414 (LY) or placebo (PL) in patients (pts) with metastatic castration-resistant prostate cancer (mCRPC) after progression on abiraterone.

5009 Background: Preclinical and phase 1 results suggest PI3K/mTOR pathway inhibition may enhance androgen receptor inhibition. We report the results of a double-blind, placebo-controlled, randomized Phase 1b/2 study of ENZ±LY (a dual PI3K/mTOR inhibitor) in pts with mCRPC who progressed on abiraterone. Methods: Phase 1b pts received single-agent LY 200 mg twice daily (BID) for 1 wk prior to starting LY+ENZ. Phase 2 pts were randomized 1:1 to 160 mg daily ENZ with PL or 200 mg BID LY on a 28-d cycle. The primary objective was progression-free survival (PFS: serological, radiographic [rPFS], or death) by PCWG2 criteria. Secondary objectives were rPFS, safety, decline in PSA, and PK. Exploratory biomarker analyses included outcomes by presence of androgen receptor variant 7 (AR-V7). 92 primary PFS events were needed for the study to have at least 80% power at one-sided alpha=0.20. Results: LY+ENZ was tolerable during Phase 1b with 1 dose limiting toxicity observed in 13 enrolled pts. Mean LY exposures remained in an efficacious range despite a 30% average decrease when combined with ENZ. In Phase 2, 129 pts were randomized to LY+ENZ (N=65) and PL+ENZ (N=64) (Table). Median PCWG2-PFS was 3.7 mos (LY+ENZ) vs 2.9 mos (PL+ENZ) (HR 0.66, 95% CI 0.43, 0.99; p-value 0.0208). Conclusions: Combination LY+ENZ had a clinically manageable safety profile. The primary end-point of PCWG2-PFS was met and is supported by a clinically meaningful delay in rPFS in AR-V7 negative pts. The biomarker data provide important insights to inform future development strategies. Clinical trial information: NCT02407054. [Table: see text]

A phase II study of enzalutamide (Enz) with dutasteride (Dut) or finasteride (Fin) in men ≥ 65 years with hormone-naive systemic prostate cancer (HNSPCa): Tolerability and geriatric asssessment (GA) results.

e16518 Background: Older men are at a high risk for adverse events (AEs) from androgen deprivation therapy (ADT). In this phase II study, we evaluated Enz and Dut/Fin in lieu of ADT for at-risk older patients with HNSPCa. Methods: Eligible patients were ≥65 years (y); at high risk of AEs from ADT by GA or treating physicians; metastatic (M1) or non-metastatic (M0) HNSPCa with a PSA doubling time ≤ 9 months and testosterone > 50ng/dl. They received Enz 160 mg/day and Dut 0.5 mg/day or Fin 5 mg/day until disease progression. GA was performed at baseline and week (wk) 61 and/or at the time of progression. GA included validated tests: Instrumental Activities of Daily Living (IADL), fall history, Short Physical Performance Battery (SPPB), Geriatric Depression Scale (GDS), and Montreal Cognitive Assessment (MOCA). The prevalence of impairment for each assessment was calculated; change in prevalence from baseline to wk 61 was analyzed using paired sample t-test. Results: 43 patients were enrolled in the study. Median age at enrollment was 78 y (range 66-94) and 93% were ECOG 0-1; 37% (n = 16) had M0 and 63% (n = 27) had M1 HNSPCa, with the majority (67%) having Gleason 6 or 7 disease. At baseline, 18.6% met the cutoff for impairment for IADLs, 53.7% for SPPB, 7.9% for GDS and 64.3% for MOCA; 9.8% had a recent fall. Median baseline PSA was 11.38 ng/ml (range: 2-145). At the time of analysis, 29 men (67.4%) remain on study treatment. 95.3%, 74.4% and 46.5% of patients reported at least one Grade 1, 2 or 3 AE respectively. No patient had a Grade 4 AE and one Grade 5 AE was reported but was an unrelated event. The most common Grade 3 AEs were hypertension (27.8%), GI (19.4%), and cardiac (8.3%); all Grade 3 GI AEs reported were deemed unrelated to the study drugs. Only impairment in ≥ 1 IADL showed a statistically significant increase in prevalence at wk 61 of treatment (40.6%) compared to baseline (18.6%, p = 0.036). Conclusions: For older men with HNSPCa, Enz with Dut/Fin demonstrated efficacy with reasonable toxicity profile, and no significant impact on the majority of GA domains. Clinical trial information: NCT02213107.

Phase 1B study of enzalutamide (ENZA) with or without sorafenib (SORA) in patients (pts) with advanced hepatocellular carcinoma (HCC).

4083Background: Preclinical models indicate that androgen receptor (AR) interference with ENZA is deleterious to HCC; however, ENZA also activates feedback circuitry that may be overcome with the a...

C15-153: Randomized phase IB/II study of enzalutamide with and without ribociclib in patients with metastatic castrate resistant, chemotherapy naïve prostate cancer that retains RB expression.

TPS384 Background: Current data suggests RB function is often attenuated in tumors through hyperphosphorylation; thus, RB activity can be “re-awakened” in RB+ tumors by suppressing key kinases that phosphorylate RB (CDK4/6). Recent findings identified perturbations of the RB tumor suppressor as a major mechanism of androgen receptor (AR) deregulation and castration-resistant prostate cancer (CRPC) formation. Our preclinical studies indicate RB+ tumors are exquisitely responsive to CDK4/6 inhibitors, revealing tumor-specific cytostatic and cytotoxic effects. These analyses strongly support the use of CDK4/6 inhibitors to activate the RB pathway, and impede the transition to CRPC. We hypothesize the CDK4/6 inhibitor ribociclib (ribo) in combination with enzalutamide (enz) in patients (pts) with progressive metastatic CRPC (mCRPC) that retains RB expression will significantly increase the efficacy of enz. Methods: This is a phase IB/II study of pts with mCRPC with RB+ tumors who have not received chemotherapy. Since ribo and enz have not been combined together in pts, the standard doses of enz and a traditional 3x3 dose escalation schema will be used in phase I to establish the safe dose of the combination; this dose will be used in phase II. Since both drugs are metabolized via the liver, plasma concentrations of ribo and enz will be monitored. To determine if ribo will improve the clinical activity in pts treated with enz, a randomized (1:1) phase II study using enz as the control arm vs. the combination will follow. This study will evaluate an early clinical activity readout, thus the primary phase II endpoint will be a proportion of pts with ≥ 50% PSA decline at 12 weeks. Secondary endpoints are rPFS, PSA PFS, OS and safety. If there is clinical activity noted, further randomized testing will be required to establish ribo clinical benefit in combination with enz. 5 sites are participating, managed by the Prostate Cancer Clinical Trials Consortium. Dose Levels 1 and 2 have been completed without any DLTs in the phase I portion of the study. A review of Dose Level 3 is planned for October 2017. Clinical trial information: NCT02555189.

Phase II study of enzalutamide monotherapy with radiation therapy for intermediate risk prostate cancer.

58 Background: Castrating androgen deprivation therapy (ADT) is standardly prescribed in combination with radiation therapy (RT) for intermediate or high-risk prostate cancer (PCa). ADT is associated with multiple side effects including weight gain, loss of libido, hot flashes and muscle atrophy. In contrast, enzalutamide monotherapy is associated with much fewer side effects. Methods: At Dana-Farber/ Harvard Cancer Center we performed an open label phase II study of enzalutamide for 6 months as neo- and adjuvant treatment for intermediate risk PCa patients (NCCN criteria) receiving RT. The primary endpoint was the proportion of patients achieving a PSA response of ≤0.2 . This endpoint is predictive of long term PSA response in a similar risk-group of patients treated with RT and ADT. PSA values were obtained at baseline and monthly on 6 cycles of enzalutamide (160mg/day). 79.2 Gy in 44 fractions of IMRT was started between 6 and 10 weeks after the initiation of enzalutamide. Quality of life questionnaires, hormone levels and anthropomorphic measurements were obtained. Results: 45 of 60 evaluable patients had a PSA ≤0.2 at the end of 6 months of enzalutamide. With a sample size of 64 evaluable patients, if the number achieving a PSA level is ≤0.2 is 44 or more, the null hypothesis is rejected with a target error rate of alpha = 0.10. Also 54 of 60 evaluable patients had a PSA of ≤0.5ng/ml. Importantly, less than half of the participants experienced erectile dysfunction or decreased libido and these were predominantly grade I. Less than a quarter of patients reported hot flashes (all grade I). Waist circumference did not change with therapy. The most frequent grade 2 or greater events were hypertension and gynecomastia. Testosterone and free testosterone levels rose significantly on enzalutamide therapy. Conclusions: Enzalutamide monotherapy with RT may be as effective as castrating ADT, and associated with fewer side effects. Larger, randomized trials are needed to further evaluate enzalutamide monotherapy, instead of ADT, to be used in combination with RT. Clinical trial information: NCT0208988.

Overall survival (OS) in patients (Pts) with diagnostic positive (Dx+) breast cancer: Subgroup analysis from a phase 2 study of enzalutamide (ENZA), an androgen receptor (AR) inhibitor, in AR+ triple-negative breast cancer (TNBC) treated with 0-1 prior lines of therapy.

1089 Background: The AR may be a novel therapeutic target for pts with AR-driven TNBC. ENZA, a potent AR inhibitor approved in men with metastatic prostate cancer, was evaluated in this phase 2 study of pts with AR+ TNBC. A genomic signature associated with AR-driven biology was identified; updated OS results in pts treated with 0-1 prior lines of therapy are presented. Methods: This is an open-label, Simon two-stage study (NCT01889238) of ENZA monotherapy in advanced AR+ TNBC (AR > 0% by IHC). Bone-only disease and unlimited prior regimens were allowed; CNS metastases or seizure history were exclusionary. The primary endpoint was clinical benefit rate at 16 weeks (CBR16) in evaluable pts (AR > 10% and ≥1 postbaseline assessment). OS was an exploratory endpoint. Results in intent-to-treat (ITT) and evaluable pts were presented previously (Traina TA et al. J Clin Oncol. 2015;33:1003). Results: 118 pts were enrolled (ITT). CBR16 in 78 evaluable pts was 33.3%. Of the 118 ITT pts, 56 were Dx+ and 62 were Dx–; ≥50% received 0-1 prior lines of therapy (28 Dx+, 37 Dx–). As of 26 Nov 2016 there were 83 deaths (median follow-up 28 mo); median OS (mOS) was 13 mo (95% CI; 8-18). In the Dx+ subgroup there were 32 deaths (mOS 20 mo [95% CI; 13-29]) vs 51 deaths in the Dx– subgroup (mOS 8 mo [95% CI; 5-11]). In pts with 0-1 prior lines of therapy, there were 13 deaths in the Dx+ subgroup (mOS 29 mo [95% CI; 19-not reached] vs 28 in the Dx– subgroup (mOS 10 mo [95% CI; 7-15]). The most common adverse events (AEs) were fatigue and nausea; fatigue was the only grade 3 related AE in > 5% of pts. A multi-covariate Cox analysis identified Dx status (+ vs –) and line of therapy (0-1 vs ≥2) as the only variables significantly associated with OS. Conclusions: In this study, the mOS of pts with Dx+ TNBC who received 0-1 prior lines of therapy appears longer than that of unselected historic controls. ENZA may represent a therapeutic option in pts with AR+ TNBC who would otherwise receive cytotoxic chemotherapy and is currently being evaluated in ENDEAR, a phase 3 study in pts with Dx+ advanced TNBC and 0-1 prior lines of therapy. Clinical trial information: NCT01889238.

A randomized study of enzalutamide in patients with localized prostate cancer undergoing active surveillance (ENACT).

TPS5097 Background: Prostate cancer (PC) patients (pts) who select active surveillance (AS) are a heterogeneous population with varying risks for disease progression. Studies have estimated that approximately 31–42% of pts electing AS have experienced disease progression (pathological or therapeutic) over 1.8 and 2.3 years. There is no evidence-based pharmacological intervention which has effectively lessened this progression event. Pharmacological intervention with enzalutamide (ENZ), an androgen receptor inhibitor approved for treatment of metastatic castration-resistant PC, may lessen this progression. The aims of this study are to evaluate the efficacy of ENZ versus AS alone for delaying time to progression in pts with clinically localized PC undergoing AS. This study examines the effects of ENZ on progression in a subset of pts with low- or intermediate-risk PC who would otherwise elect an AS protocol. Methods: This is a multicenter, randomized, open-label study (NCT02799745). Eligibility criteria include histologically confirmed prostate adenocarcinoma within 6 months of screening, low or intermediate risk PC (T1c−T2c, prostate-specific antigen [PSA] < 20, N0, M0, Gleason score ≤7 [3+4 pattern only]), Eastern Cooperative Oncology Group status ≤2 and estimated life expectancy > 5 years. Exclusion criteria include any prior PC intervention. Pts will be randomized to receive open-label oral ENZ 160 mg/day once daily or to AS during the 1-year study treatment period. After the first year, all pts will be followed for one additional year with no other intervention. All pts will undergo prostate biopsy at 1 and 2 years. The primary end point is time to PC progression (pathological or therapeutic). Secondary end points include safety, incidence of negative biopsies for cancer at 1 and 2 years, percentage of cancer positive cores at 1 and 2 years, time to PSA progression, incidence of secondary rise in serum PSA, and quality-of-life questionnaires. Exploratory end points include biomarker assessment and genomic analysis. Study enrolment commenced in June 2016, with study completion expected in March 2019. Planned total enrolment is 222 pts from ~60 United States/Canadian sites. Clinical trial information: NCT02799745.

Androgen receptor-positive, triple-negative breast cancer.

Androgen receptor-positive, triple-negative breast cancer.

Phase I/Ib study of enzalutamide and gemcitabine and cisplatin in bladder cancer.

338 Background: Metastatic bladder cancer (mBC) is a fatal disease and novel therapies are urgently needed. Preclinical evidence suggests role of AR in BC progression. Enzalutamide (ENZ) is a novel AR antagonist that inhibits nuclear translocation of AR, DNA binding, and co activator recruitment. Our ongoing phase 1 trial is is assessing safety and tolerability of ENZ in combination with gemcitabine and cisplatin (GC) in mBC and explore novel correlatives in tumor tissues and CTCs. Methods: The study has 2 phases, dose escalation phase and dose expansion phase. The dose escalation phase had 2 cohorts testing ENZ at doses of 80 mg and 160 mg respectively with GC (gemcitabine 10000 mg/m2 on days 1 and 8 and cisplatin 70 mg/m2 on day 1 every 21 days). The dose escalation phase allowed both AR + and AR - mBC pts. Patients will be monitored for safety and tolerance with laboratory studies, clinical exam, and CT scans to assess response. Primary objective is safety and tolerability of ENZ and GC. Secondary objectives are objective tumor response, time to progression, and overall survival. Exploratory objectives include qualitative and quantitative evaluation of AR and pAKT expression with AQUA in tumor tissues and correlation with outcomes. CTCs are being evaluated at baseline and cycle 3, including AR expression in CTCs and correlation will be done with tumor AR expression and clinical outcomes. Key eligibility criteria are ECOG PS of 0-1, and no contraindications to study drugs. Results: In the dose expamnsion phase, 3 patients were enrolled in each cohort of 80 mg and 160 mg of ENZ respectively with GC and there were no DLTs or significant AEs related to the combination; the MTD of ENZ is 160 mg. Enrollment on dose expansion phase is ongoing. detectable CTCs were seen in 4/6 BC patients with 2 patients showing AR + CTCs at baseline. Further CTC analysis, including AR expression and tissue analysis for AR and pAKT analysis in tissues is ongoing. (Trial identifier: NCT02300610). Conclusions: This is a first of its kind clinical trial exploring the role of AR signaling in BC and targeting it with ENZ along with GC. The data gathered form this study will help us understand the clinical relevance of targeting AR in BC. Clinical trial information: NCT02300610.

A phase I dose-escalation study of enzalutamide in combination with the AKT inhibitor AZD5363 in patients with mCRPC.

135 Background: Activation of the PI3K/AKT/mTOR pathway may contribute to resistance to androgen receptor targeted therapies in metastatic CRPC (mCRPC). The phase I/II RE-AKT trial (NCT02525068) investigates the safety and activity of enzalutamide (enza) in combination with the AKT inhibitor, AZD5363, in patients (pts) with mCRPC. Results of the phase I run-in are reported. Methods: mCRPC pts progressing after 1-2 lines of taxane chemotherapy and at least 12 weeks (wks) of abiraterone or enza were treated with enza (160mg od) and AZD5363 bid 4-days on, 3-days off, in a 3+3 dose escalation design. Co-primary endpoints were to assess toxicity (CTCAE), and identify the recommended phase II dose (RP2D) of AZD5363; antitumour activity and pharmacokinetics (PK) were secondary endpoints. Response was assessed by PSA, RECIST v1.1 and circulating tumor cell (CTC) conversion. Pts were considered evaluable for response if they completed 12 wks of treatment. Results: 16 pts were enrolled between 12/2014 & 04/2016 with 15 receiving treatment. At the AZD5363 320mg dose 3 pts were treated with no dose limiting toxicity (DLT). At the AZD5363 480mg dose, 5 pts were treated with 2 DLTs of grade (G) 3 maculopapular rash (MPR) related to AZD5363. An intermediate dose level of AZD5363 400mg was selected with 7 pts treated. 1 pt withdrew consent prior to completing the DLT window. 1 DLT of G3 MPR occurred and this dose was selected as the RP2D. Non-DLT treatment related (TR) G3/4 adverse events (AEs) were hyperglycaemia (n = 4, 26.7%), neutropenia (n = 1, 6.7%) & diarrhea (n = 1, 6.7%). All other TR AEs were G1 or G2, with diarrhea (n = 9, 60%), anorexia (n = 8, 53.3%) & nausea (n = 7, 46.7%) being most common. Of the 10 pts who completed 12 wks of treatment, 3 met at least one of the criteria for response. 1 pt (AZD5363 320mg) who had previously progressed on enza exhibited RECIST v1.1 partial response, > 50% PSA response, and CTC conversion by wk 13. Enza decreased AZD5363 PK exposure; robust modulation of pS6, pGSK3b and pPRAS40 was demonstrated. Conclusions: AZD5363 at the RP2D of 400mg bid 4 days on, 3 days off combined with enza 160mg od is safe and tolerable. Antitumor activity is reported, suggesting that AZD5363 may be able to overcome resistance to enza. Clinical trial information: NCT02525068.

A phase II study of enzalutamide (Enz) with dutasteride (Dut) or finasteride (Fin) in men ≥ 65 years with hormone-naive systemic prostate cancer (HNSPCa).

179 Background: Older men are at a high risk for adverse events (AEs) from androgen deprivation therapy (ADT). In prior studies, peripheral androgen blockade with bicalutamide and Fin was better tolerated but less efficacious than ADT in HNSPCa. The potential syngerism of Enz (a potent antiandrogen) and Dut/Fin (5-a reductase inhibitors for conversion of testosterone [T] to dihydrotestosterone [DHT]) provided the rationale for this Phase II study that examined the clinical efficacy and safety of Enz with Dut/Fin in men > 65 years with HNSPCa. Methods: Eligible patients were > 65 years (y) ; at a high risk of AE from ADT by comprehensive geriatric assessment or treating physicians; had metastatic (M1) or biochemical recurrent (M0) HNSPCa with a PSA doubling time < 9 months; and had T > 50ng/dl. They received Enz (160mg daily) and Dut (0.5mg daily) or Fin (5mg daily) until disease progression according to the Prostate Cancer Working Group 2 guidelines. The primary study endpoint is time to PSA progression. The secondary endpoints are time to PSA nadir and treatment-related AEs. Results: As of July 31, 2016, 24 patients were screened (3 ineligible) and 21 were enrolled with a median follow-up of 31 weeks (7-79). Median age at enrollment was 79.5 y (66-94) and 14 %, 72% and 14% had ECOG performance status of 0, 1, and 2, respectively. 57% (n = 12) had M0 and 43% (n = 9) had M1 HNSPCa, with 18%, 62%, 5%, and 10% having Gleason 6, 7, 8, and 9 disease, respectively (5% with unkown Gleason sum). The median PSA at enrollment was 12 ng/ml (2-102). The median time to 90% PSA decline after treatment initiation was 7 weeks (7-20) and 92% achieved 80% DHT decline in 9 months. At the time of analysis, all patients had ongoing PSA decline of > 90% without radiographic evidence of disease progression. Common Grade 1 AEs included gynecomastia (28%), fatigue (28%), hot flashes (19%) and paresthesias (15%). One patient withdrew from the study due to Grade 2 paresthesia. None had Grade 3 or 4 treatment-related AEs. One patient died due to colitis unrelated to study treatments. Conclusions: Enz with Dut/Fin appears to have clinical activity for older patients with M0 and M1 HNSPCa with acceptable side effects. Clinical trial information: NCT02213107.

Abstract P6-07-01: Development of a Prosigna® (PAM50)-based classifier for the selection of advanced triple negative breast cancer (TNBC) patients for treatment with enzalutamide

Background: Enzalutamide is an orally administered androgen receptor (AR) inhibitor approved by the FDA for use in men with metastatic castrate-resistant prostate cancer. A recent phase II study of enzalutamide in patients with advanced, AR positive, TNBC (NCT01889238) demonstrated significant improvements in both PFS and OS for patients whose tumors exhibited a gene expression (Gx) profile enriched in AR signaling and luminal biology. A PAM50-based signature was developed from the phase 2 study which used next generation RNA sequencing (NGS) to identify patients likely to respond to enzalutamide. We transitioned the test to the NanoString (NS) nCounter® Analysis System using Prosigna reagents to support clinical validation in a phase 3 trial. Here we describe the development and analytical performance of the NanoString Androgen Gene Expression Profiling Assay-1 (NS-AR-01). Methods: The NS-AR-01 algorithm coefficients were calibrated from the Predict AR algorithm by testing FFPE tumor tissue from patients who were pre-screened but not enrolled in the phase II study with both platforms (NGS and NS). Three unique algorithms were developed and subsequently challenged with an independent sample set with NGS data to provide an unbiased evaluation of the concordance of the platforms. A pre-specified clinical accuracy verification study was performed through prediction of NS-AR-01 scores from the NGS Gx data from the patients included in the phase 2 study efficacy analysis. The final NS-AR-01 algorithm was selected based on performance in the clinical accuracy verification. The final NS-AR-01 algorithm was evaluated in the 118 patients included in the ITT analysis, as well as those treated with 0-1 lines of prior therapy. The analytical performance of the assay was characterized by testing precision from RNA, reproducibility from FFPE tissue, sensitivity to RNA input amounts, and the impact of common interferents. Results: All three algorithm translations met the pre-specified clinical accuracy verification acceptance criteria. The final NS-AR-01 algorithm generated a hazard ratio most similar to that observed from the NGS algorithm. The total standard deviation when testing multiple FFPE sections from the same block was Citation Format: Danaher P, Skewis L, Mashadi-Hossein A, Ram N, Gowen-MacDonald J, Harris E, Ferree S, Buckingham W. Development of a Prosigna® (PAM50)-based classifier for the selection of advanced triple negative breast cancer (TNBC) patients for treatment with enzalutamide [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-07-01.

1802 Overall survival (OS) from the phase 2 study of enzalutamide (ENZA), an androgen receptor (AR) signaling inhibitor, in AR+ advanced triple-negative breast cancer (aTNBC)

1802 Overall survival (OS) from the phase 2 study of enzalutamide (ENZA), an androgen receptor (AR) signaling inhibitor, in AR+ advanced triple-negative breast cancer (aTNBC)

2501 ORAL A randomized, open-label, phase 2 study of enzalutamide as neoadjuvant therapy for patients undergoing prostatectomy for localized prostate cancer

2501 ORAL A randomized, open-label, phase 2 study of enzalutamide as neoadjuvant therapy for patients undergoing prostatectomy for localized prostate cancer

Results from a phase 2 study of enzalutamide (ENZA), an androgen receptor (AR) inhibitor, in advanced AR+ triple-negative breast cancer (TNBC).

1003 Background: The AR may be a therapeutic target for pts with androgen-driven TNBC. ENZA, a potent AR inhibitor, is approved in men with metastatic castration-resistant prostate cancer (mCRPC) and improves median PFS compared to bicalutamide in men with mCRPC (15.7 vs 5.8 mos; HR 0.44; p 0% by IHC; NCT01889238). Pts could be prescreened for AR, and have non-measurable bone disease and unlimited prior regimens; CNS metastases or seizure history were exclusionary. The primary endpoint was clinical benefit (CR, PR or SD) at 16 wks (CBR16) in ‘Evaluable’ pts defined as having both AR IHC ≥10% and a response assessment. CBR24, PFS, response rate, and safety were assessed. An androgen-driven gene signature (Dx) was created from gene profiling and outcomes were assessed accordingly. Stage 2 enrolled if CBR16 was ≥3 of 26 Evaluable pts; H0 was rejected if CBR16 was ≥9 in 62 yielding 85% po...

Long-term Safety and Antitumor Activity in the Phase 1–2 Study of Enzalutamide in Pre- and Post-docetaxel Castration-Resistant Prostate Cancer

BackgroundGiven that some patients with castration-resistant prostate cancer (CRPC) have shown extended responses to the androgen receptor inhibitor enzalutamide, long-term safety of this drug is of interest. ObjectiveTo evaluate the long-term safety and antitumor activity of enzalutamide in CRPC patients. Design, setting, and participantsThis phase 1–2 study evaluated enzalutamide in 140 CRPC patients with and without prior chemotherapy. Initial findings were published in 2010. We report updated results from an additional 17-mo follow-up for antitumor activity and >4 yr for safety. InterventionPatients received 30–600mg/d oral enzalutamide. During long-term dosing, all patients were switched first to the maximum tolerated dose of 240mg/d and then to the phase 3 dose of 160mg/d. Outcome measurements and statistical analysisSafety was assessed regularly. The Kaplan-Meier method was used to estimate the distributions of time to prostate-specific antigen (PSA) progression and time to radiographic progression. Results and limitationsThe safety profile of enzalutamide was consistent over time, with little change in the rates of commonly reported adverse events (AEs) or the incidence of grade 3/4 AEs. Fatigue of any grade was the most common dose-dependent AE, experienced by 70% of patients, with 14% of patients reporting grade 3/4 fatigue. The median time to PSA progression was not reached for chemotherapy-naive patients and was 45 wk for postchemotherapy patients; the corresponding median time to radiographic progression was 56 wk and 25 wk. ConclusionsEnzalutamide showed durable antitumor activity in chemotherapy-naive and postchemotherapy patients, and was well tolerated, even in patients treated for 4 yr. Patient summaryEnzalutamide was active against prostate cancer and was well tolerated, even for up to 4 yr of treatment, supporting its potential for long-term use in men with prostate cancer. Fatigue was the most common side effect, occurring at varying degrees of severity in most patients.

P057 PROSPER: A phase 3 study of enzalutamide in non-metastatic (M0) castration-resistant prostate cancer (CRPC) patients

P057 PROSPER: A phase 3 study of enzalutamide in non-metastatic (M0) castration-resistant prostate cancer (CRPC) patients