Trial Of Enzalutamide Research Articles

China ARCHES: A Phase 3 Trial of Enzalutamide vs Placebo in Metastatic Hormone-Sensitive Prostate Cancer

Purpose: This study evaluated the efficacy and safety of enzalutamide vs placebo, both combined with androgen deprivation therapy, in Chinese men with metastatic hormone-sensitive prostate cancer. Materials and Methods: Patients were randomized 2:1 to enzalutamide 160 mg/day or placebo, both in combination with androgen deprivation therapy. The primary trial end point was the time to prostate-specific antigen progression. Selected secondary end points included radiographic progression-free survival, time to castration resistance, time to initiation of new antineoplastic therapy, undetectable prostate-specific antigen (<0.2 ng/mL) rate among patients with detectable levels at baseline, and safety. Results: From September 11, 2019, to November 18, 2022, 180 patients were randomized to treatment (enzalutamide: n = 120; placebo: n = 60). Baseline characteristics were balanced between the treatment arms. Median treatment duration in the enzalutamide vs the placebo arm was 25.66 vs 15.11 months. After 63 prostate-specific antigen progression events (enzalutamide: n = 23; placebo: n = 40), enzalutamide significantly reduced the hazard for prostate-specific antigen progression by 87% (hazard ratio: 0.130; 95% confidence interval: 0.076, 0.222; P < .0001) vs placebo. Radiographic progression-free survival, time to castration resistance, and achievement of undetectable prostate-specific antigen levels were increased with enzalutamide vs placebo, while treatment-emergent adverse event rates were similar. Serious and grade 3 to 4 treatment-emergent adverse events occurred in 35.3% and 52.1%, respectively, of enzalutamide recipients vs 20.3% and 39.0%, respectively, of placebo recipients. Conclusions: In Chinese men with metastatic hormone-sensitive prostate cancer, enzalutamide significantly reduced the hazard for prostate-specific antigen progression vs placebo when combined with androgen deprivation therapy. The China ARCHES (NCT04076059) results were consistent with those of the global ARCHES study (NCT02677896).

A Phase I Trial of Enzalutamide Plus Selective Glucocorticoid Receptor Modulator Relacorilant in Patients with Metastatic Castration-Resistant Prostate Cancer.

The majority of patients with metastatic prostate cancer who receive androgen-deprivation therapy and androgen receptor (AR) signaling inhibitors (ARSI) progress. Activation of the glucocorticoid receptor (GR) is associated with ARSI resistance. This single-arm phase I trial assessed safety and pharmacokinetic (PK) feasibility of a combined AR antagonist (enzalutamide) and selective GR modulator (relacorilant) in patients with metastatic castration-resistant prostate cancer (mCRPC). This was a phase I trial (NCT03674814) of relacorilant and enzalutamide in patients with refractory mCRPC enrolled using a 6+3 design. The enzalutamide dose was kept constant at 120 mg/d with escalating doses of relacorilant based on safety and PK measures in cohorts of ≥6 patients. The primary objective was safety and establishment of pharmacologically active doses. Secondary objectives were related to antitumor activity. Thirty-five patients with mCRPC were enrolled. Twenty-three were accrued across three dose cohorts in the dose-escalation phase, and 12 enrolled at the recommended phase II dose. The combination was generally well tolerated, safe, and achieved desirable enzalutamide PK. RP2D of 120 + 150 mg/d, respectively, was established. Median time on study was 2.2 months with four patients remaining on study for longer than 11 months. Four of 12 evaluable patients had a prostate-specific antigen (PSA) partial response. This is the first prospective trial combining an AR antagonist and a nonsteroidal selective GR modulator. The combination was safe and well tolerated with PSA response and prolonged disease control observed in a limited subset of patients. Further prospective trials are justified to evaluate efficacy and identify predictive biomarkers of response.

Phase I trial of enzalutamide (Enz) plus the glucocorticoid receptor antagonist relacorilant (Rela) for patients with metastatic castration resistant prostate cancer.

5062 Background: Resistance to androgen receptor (AR) targeted therapies is common in mCRPC. Glucocorticoid receptor (GR) expression increases with AR inhibition in patients (pts) and blockade of GR signaling inhibits CRPC growth in preclinical models when combined with AR blockade. We thus conducted a phase I study of the combination of rela and enz in patients with mCRPC. Methods: The study used a 6+3 design to assess safety and pharmacokinetics (PK) of the 2-drug combination. The starting dose of rela 100mg/day was chosen based on current clinical studies indicating this dose was both safe for daily dosing and pharmacologically active and the starting dose for Enz was 120mg based on anticipated drug-drug interactions. Escalating doses of rela were combined with Enz 120 using pre-specified dose escalation rules. An additional 12 patients were to be assessed at the MTD to refine safety and PK profiles. Primary endpoint was safety of the combination and to establish safe and pharmacologically active doses of both agents. Key secondary endpoints were tumor response per RECIST 1.1 criteria and progression-free survival (PFS; defined as either PSA progression, radiographic progression or death). PSA was measured after 12 weeks or at the last time at which PSA data was available, including times <12 weeks. Results: 35 pts were enrolled. Pts had a median age of 74 (range 62-85) and baseline PSA of 89.5 (range 7.3-2391). 100% had prior potent AR signaling inhibitor (abi or enz) with 89% receiving prior enz, 94% prior abi, 83% prior both. 69% of pts received prior docetaxel. Median PSA change was 0.1%. Enz 120mg + Rela 100mg and Enz 120+Rela 150 were found to be safe and tolerable and achieved desirable Enz PK. DLTs were noted in 3 pts at the 200mg Rela dose, which was deemed to have exceeded the MTD, which was thus defined as 150mg Rela+120mg Enz. Most common ≥ grade 3 treatment related adverse events (TRAEs) were fatigue (11% of pts), anemia (9%), abdominal pain (6%) and pericardial effusion (6%). Median PFS was 2.5 months for 21 of 35 evaluable pts. Best response per RECIST 1.1 were Not Evaluable (40%), SD (34%) & PD (26%). No CR or PR were noted. Most common reasons for discontinuation from trial included progressive disease/hospice (82%), AEs (12%), physician discretion (3%) & death (3%). 2 pts remain on trial as of data cutoff (12/31/22). Conclusions: The combination of enzalutamide and relacorilant was safe & largely well tolerated. The majority of pts were discontinued from trial due to progressive disease or hospice. Further analyses of secondary & correlative endpoints such as translational/endocrine biomarkers, GR target gene expression and circulating tumor cells are ongoing. Clinical trial information: NCT03674814 .

Alliance A031902 (CASPAR): A randomized phase (ph) 3 trial of enzalutamide with rucaparib/placebo in first-line metastatic castration-resistant prostate cancer (mCRPC).

TPS277 Background: Despite a growing number of treatment options for first-line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Co-inhibition of androgen receptor (AR) and PARP is a promising therapeutic strategy that leverages synthetic lethality induced by impaired double-strand DNA repair. Two phase III studies have shown improvement in radiographic progression-free survival (rPFS) in HRR-mutant pts with abiraterone + PARPi combinations vs abiraterone alone. However, the results in HRR-wild type pts are conflicting, with only one of the studies demonstrating a benefit with the abiraterone + PARPi combination. ENZ + RUCA has shown an acceptable safety profile & no significant drug-drug interactions (S-DDI) in a phase 1b trial. This allows its evaluation in mCRPC. Methods: CASPAR (A031902) is a phase 3 study in which 984 pts will be randomized on a 1:1 basis to ENZ plus RUCA/PBO. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue is available). Treatment will be continued until disease progression and crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or non-measurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, and no medications with S-DDI with ENZ/RUCA. Hierarchical co-primary endpoints are overall survival (OS) and rPFS. The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 and 21 months in control and combination arms, respectively), and 80% power to detect an HR of 0.80 in OS (median OS of 32 and 40 months, respectively). Key secondary endpoints are rPFS and OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; and differences in adverse events and quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF), and EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA testing for HRR gene alterations. Enrollment began in July 2021 & the study is available for participation to all US-NCTN sites. Clinical trial information: NCT04455750 .

Alliance A031902 (CASPAR): A randomized, phase (ph) 3 trial of enzalutamide with rucaparib/placebo in first-line metastatic castration-resistant prostate cancer (mCRPC).

TPS5107 Background: Despite a growing number of treatment options for first line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Androgen receptor (AR) signaling inhibition increases genomic instability with double-strand DNA breaks & co-inhibition of AR & PARP induces synthetic lethality in multiple preclinical models. Homologous recombination repair (HRR) gene aberrations do not appear to be necessary for this synergy as demonstrated in a ph 3 clinical trial of abiraterone & olaparib where this combination improved radiographic progression-free survival (rPFS) in HRR-wild-type pts compared with abiraterone alone. A ph 1b trial has since shown that enzalutamide plus rucaparib has acceptable safety profile & no significant drug-drug interactions (S-DDI). Methods: CASPAR/A031902 (NCT04455750) is a ph 3 study in which 984 pts will be randomized 1:1 to enzalutamide plus rucaparib or placebo. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted-exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue available). Treatment will be continued until disease progression & crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or nonmeasurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, & no medications with S-DDI with enzalutamide/rucaparib. Hierarchical co-primary endpoints are rPFS & overall survival (OS). The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 & 21 months in control & combination arms, respectively) & 80% power to detect an HR of 0.80 in OS (median OS of 32 & 40 months, respectively). Key secondary endpoints are rPFS & OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; & differences in adverse events & quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF) & EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA-based testing for alterations in HRR genes. Enrollment to CASPAR began in July 2021 & the study is available for participation to all US-NCTN sites with a projected enrollment of 3 years. Support: U10CA180821, U10CA180882, U24CA196171; U10CA180888. Clinical trial information: NCT04455750.

Alliance A031902 (CASPAR): A randomized, phase (ph) 3 trial of enzalutamide with rucaparib/placebo as novel therapy in first-line metastatic castration-resistant prostate cancer (mCRPC).

TPS194 Background: Despite a growing number of treatment options for first line mCRPC, approximately 40% of patients (pts) have radiographic progression within the first year. Androgen receptor (AR) signaling inhibition increases genomic instability with double-strand DNA breaks & co-inhibition of AR & PARP induces synthetic lethality in multiple preclinical models. Homologous recombination repair (HRR) gene aberrations do not appear to be necessary for this synergy as demonstrated in a ph 2 clinical trial of abiraterone & olaparib where this combination improved radiographic progression-free survival (rPFS) in HRR-wild-type pts compared with abiraterone alone. A ph 1b trial has since shown that enzalutamide plus rucaparib has acceptable safety profile & no significant drug-drug interactions (S-DDI). Methods: CASPAR/A031902 (NCT04455750) is a ph 3 study in which 984 pts will be randomized 1:1 to enzalutamide plus rucaparib or placebo. HRR gene aberration is not required for enrollment. All pts will undergo next-generation targeted-exome sequencing from archival tumor tissue (new biopsy only required if no archival tissue available). Treatment will be continued until disease progression & crossover is not allowed. Key eligibility criteria are age ≥ 18 years, ECOG PS 0-2, biopsy-proven prostate adenocarcinoma, progressive (PSA or radiographic) disease per Prostate Cancer Working Group 3 guidelines, measurable or nonmeasurable disease per RECIST 1.1, no prior treatment for mCRPC (prior docetaxel, abiraterone, darolutamide, or apalutamide in non-mCRPC setting is allowed), no significant uncontrolled comorbidity, & no medications with S-DDI with enzalutamide/rucaparib. Hierarchical co-primary endpoints are rPFS & overall survival (OS). The OS analysis will be undertaken as a primary endpoint if the rPFS endpoint is met. For a one-sided logrank test with a type 1 error rate equal to 0.025, the study has 90% power to detect a hazard ratio (HR) of 0.71 in rPFS (median rPFS of 15 & 21 months in control & combination arms, respectively) & 80% power to detect an HR of 0.80 in OS (median OS of 32 & 40 months, respectively). Key secondary endpoints are rPFS & OS in pts with vs without pathogenic BRCA1, BRCA2, or PALB2 alterations; & differences in adverse events & quality of life (QOL) outcomes between the treatment arms. QOL assessments include Functional Assessment of Cancer Therapy–Prostate (FACT-P), Brief Pain Inventory Short Form (BPI-SF) & EQ-5D-5L. A key correlative endpoint is the sensitivity of ctDNA-based testing for alterations in HRR genes. Enrollment to CASPAR began in July 2021 & the study is available for participation to all US-NCTN sites with a projected enrollment of 3 years. Support: U10CA180821, U10CA180882, U24CA196171; U10CA180888; Clovis Oncology; http://acknowledgments.alliancefound.org Clinical trial information: NCT04455750.

Impact of enzalutamide on patient-reported fatigue in patients with prostate cancer: data from the pivotal clinical trials

BackgroundFatigue is a multifactorial symptom commonly reported by patients with prostate cancer as a result of disease and treatment. This study assesses the impact enzalutamide has on patient-reported fatigue (“fatigue”) by using patient-reported outcomes from four pivotal, placebo-controlled trials of enzalutamide (ARCHES (NCT02677896), PROSPER (NCT02003924), PREVAIL (NCT01212991), and AFFIRM (NCT00974311)).MethodsFatigue was assessed in the individual studies using the Functional Assessment of Cancer Therapy–Prostate item GP1 at baseline, weeks 13 or 17, and every 12 weeks until disease progression. Longitudinal changes were assessed using mean scores and mixed-model repeated measures.ResultsThe fatigue rates at baseline were higher in patients with later-stage disease (metastatic and/or castration-resistant prostate cancer (CRPC)) and among patients who had already received prior treatment lines; rates ranged between 58% in PROSPER (nonmetastatic CRPC) and 86% in AFFIRM (post-docetaxel metastatic CRPC). Irrespective of disease state, initiation of enzalutamide or placebo resulted in an early increase of fatigue (by weeks 13 or 17), with fatigue levels stabilizing thereafter. At last assessment, ≥55% of patients reported fatigue improvement or stabilization in all trials compared to baseline. More patients reported fatigue worsening by ≥1 or ≥2 units with enzalutamide plus androgen deprivation therapy (ADT) than with placebo plus ADT in ARCHES, PROSPER, and PREVAIL, but the between-group difference was <10% in all trials.ConclusionsThe levels of fatigue were greater in mCRPC and lower in earlier states of disease. In all trials, patients reported a small increase in fatigue for the first 13–17 weeks after starting enzalutamide or placebo, with slightly greater fatigue with enzalutamide in all studies except AFFIRM, but fatigue stabilized or improved thereafter. This suggests a role for clinical management of fatigue to help patients cope early in treatment.

A phase Ib trial of enzalutamide with venetoclax in metastatic castration-resistant prostate cancer (mCRPC).

TPS5599 Background: Androgen receptor (AR) signaling plays an important role in prostate cancer (PCa) cell survival and proliferation. Xenograft and PDX models demonstrate that untreated PCa harbors AR−/lo stem cells not critically dependent on androgens for survival.1 Furthermore, castration and enzalutamide (enza) leads to expansion of both AR−/lo and AR+/hi resistant clones in xenograft tumors, resulting in two distinct CRPC-propagating populations.2 However, most current CRPC treatments are directed towards AR+/hi cells. RNAseq revealed that BCL-2 is highly up-regulated in AR−/lo tumors post-castration and in AR+/hi CRPC tumors post-enza.2 Strikingly, BCL-2, but not BCL-XL and MCL-1, was selectively up-regulated in these xenograft tumors. These results were subsequently validated in patient CRPC datasets.2,3 Venetoclax (ven), a potent and selective BCL-2 inhibitor, inhibits enza resistance in AR+/hi CRPC and tumor growth in AR−/lo xenograft models.2 A recent phase I trial of ven combined with tamoxifen showed promising activity in ER+ and BCL2+ metastatic breast cancer.4 We hypothesize that co-targeting AR−/lo and AR+/hi PCa clones with ven and enza will prevent the emergence of enza resistance in human mCRPC. Methods: This is a phase Ib, single-center, single-arm trial of enza (160mg/d) with ven in patients with mCRPC that has progressed on previous therapies which may include anti-androgens. Three dose-levels of ven (400mg, 600mg and 800mg/d q28d) will be evaluated using a 3+3 study design. Fifteen to 18 patients will be enrolled in this phase to assess dose-limiting toxicities, maximum tolerated dose, and recommended phase II dose. Aims of correlative studies include (1) assessing the pharmacokinetic interaction between enza and ven, (2) identification of potentially predictive blood and tissue biomarkers (including pre- and post-treatment CTC levels, expression of BCL2, AR, ARv7 in pre-and post-treatment biopsies and CTCs), (3) measurement of pre- and post-treatment BCL2 expression in peripheral blood mononuclear cells as a surrogate for ven activity, and (4) the development of 3D organoid models from CTCs and biopsies. The trial is open with 3 patients enrolled to dose-level 1, and 2 patients currently at dose-level 2. Correlative studies are ongoing.

SUN-739 Next Generation AR Antagonists Increase Systemic Active Glucocorticoid Exposure by Altering Glucocorticoid Metabolism

Enzalutamide and apalutamide are potent next-generation androgen receptor (AR) antagonists used in metastatic and non-metastatic prostate cancer. Despite the increased survival benefits of these agents, resistance normally occurs and the disease transitions to its lethal form. We hypothesized that enzalutamide and apalutamide suppress 11β-hydroxysteroid dehydrogenase-2 (11β-HSD2), which normally converts cortisol to cortisone, leading to elevated cortisol concentrations and increased ratio of active to inactive glucocorticoids. We measured cortisol and cortisol/cortisone ratio (substrate/product of 11β-HSD2) in serum using mass spectrometry before and 1 month on-treatment in 3 clinical trials: 1) neoadjuvant apalutamide + leuprolide (n=25) 2) enzalutamide +/- PROSTVAC for metastatic castration-resistant prostate cancer (n=54) and 3) enzalutamide +/- PROSTVAC for non-metastatic castration-sensitive prostate cancer (n=38 patients). Progression-free survival (PFS) was determined in the metastatic CRPC study of enzalutamide +/- PROSTVAC for those with glucocorticoid changes above and below the median. A statistically significant rise in cortisol concentration and cortisol/cortisone ratio with AR antagonist treatment occurred uniformly across all 3 clinical trials. For example, a rise in cortisol/cortisone ratio occurred in 23/25 (92%) patients (p < 0.001), 36/54 (67%) patients (p < 0.001), and 30/38 (79%) patients (p = 0.051), in the 3 respective trials. In the trial of enzalutamide +/- PROSTVAC for metastatic CRPC, high cortisol/cortisone ratio in the enzalutamide arm was associated with significantly improved PSA progression-free survival and radiographic progression-free survival. However, in the enzalutamide + PROSTVAC arm, the opposite trend was observed. In conclusion, treatment with enzalutamide or apalutamide increases systemic exposure to active glucocorticoids. These findings have potential consequences for immune suppression and the efficacy of treatment combinations using next-generation AR antagonists. On-treatment, glucocorticoid changes might serve as a pharmacodynamic biomarker.

Deep androgen receptor suppression in prostate cancer exploits sexually dimorphic renal expression for systemic glucocorticoid exposure

Enzalutamide and apalutamide are potent next-generation androgen receptor (AR) antagonists used in metastatic and non-metastatic prostate cancer. Metabolic, hormonal and immunologic effects of deep AR suppression are unknown. We hypothesized that enzalutamide and apalutamide suppress 11β-hydroxysteroid dehydrogenase-2 (11β-HSD2), which normally converts cortisol to cortisone, leading to elevated cortisol concentrations, increased ratio of active to inactive glucocorticoids and possibly suboptimal response to immunotherapy. On-treatment glucocorticoid changes might serve as an indicator of active glucocorticoid exposure and resultant adverse consequences. Human kidney tissues were stained for AR and 11β-HSD2 expression. Patients in three trials [neoadjuvant apalutamide plus leuprolide, enzalutamide ± PROSTVAC (recombinant poxvirus prostate-specific antigen vaccine) for metastatic castration-resistant prostate cancer (CRPC) and enzalutamide ± PROSTVAC for non-metastatic castration-sensitive prostate cancer] were analyzed for cortisol and its metabolites using liquid chromatography-mass spectrometry (LC-MS/MS). Progression-free survival was determined in the metastatic CRPC study of enzalutamide ± PROSTVAC for those with glucocorticoid changes above and below the median. Concurrent AR and 11β-HSD2 expression occurs only in the kidneys of men. A statistically significant rise in cortisol concentration, cortisol/cortisone ratio and tetrahydrocortisol/tetrahydrocortisone ratio with AR antagonist treatment occurred uniformly across all three trials. In the trial of enzalutamide ± PROSTVAC for metastatic CRPC, high cortisol/cortisone ratio in the enzalutamide arm was associated with significantly improved progression-free survival. However, in the enzalutamide+ PROSTVAC arm, the opposite trend was observed. Enzalutamide and apalutamide treatment toggles renal 11β-HSD2 and significantly increases indicators of and exposure to biologically active glucocorticoids, which is associated with clinical outcomes.

Results from a phase I/Ib trial of enzalutamide and gemcitabine and cisplatin in metastatic bladder cancer (mBC).

471 Background: Novel targeted therapies are an unmet need in mBC. Androgen receptor (AR) is a rational target in BC and we conducted a phase 1/1b trial assessing safety and tolerability of AR antonist, enzalutamide (ENZ) in combination with gemcitabine and cisplatin (GC) in mBC. Methods: The dose escalation phase allowed patients with mBC regardless of the AR status (assessed on routine IHC) and dose expansion cohort allowed only AR+ pts. The dose escalation phase had 2 cohorts testing ENZ at doses of 80 and 160 mg respectively with GC (G 1000 mg/m2 on days 1, 8 and C 70 mg/m2 on day 1 every 21 days). After 6 cycles of ENZ+GC, pts. continued maintenance ENZ until disease progression. Primary objective was safety and tolerability of ENZ and GC. Secondary objectives were PFS, OS and objective tumor response. Exploratory objectives included evaluation of AR expression in tumor tissues and correlation with outcomes and CTC evaluation at baseline and prior to cycle 3, including AR expression in CTCs and correlation with clinical outcomes. Key eligibility criteria included ECOG PS of 0-1, and no contraindications to ENZ and GC. Results: A total of 10 pts were enrolled between Nov. 2014 and Jan. 2017; 6 pts were enrolled on the dose escalation phase, there were no DLTs observed and ENZ dose of 160 mg was used for the dose expansion cohort, which enrolled 4 pts. The combination of ENZ and GC was well tolerated with expected toxicities, mainly from GC. Median age was 65.6 yrs, 9/10 pts were male; of the 8 evaluable pts, 1 had CR, 4 had PR, 2 had SD and 1 had PD; median OS was 10.59 mos and median PFS was 7.68 mos. CTCs were detectable in 9/10 pts and correlated with disease response. The pt with CR was a female pt with strongly AR + tumor (&gt;90%) and continues to remain in CR 24 months from starting treatment. Exploratory analysis from CTCs and is ongoing. Conclusions: This is the 1st clinical trial to target AR signaling in mBC with ENZ and to evaluate safety of ENZ with GC. While there were limited number of pts enrolled, the results from this study provide early evidence that AR is a rational target in BC and anti-AR therapies can be safely combined with chemotherapy. Clinical trial information: NCT02300610.

A phase II trial of enzalutamide, docetaxel and androgen deprivation therapy (ENZADA) in patients with metastatic castrate sensitive prostate cancer (mCSPC).

TPS5094Background: The addition of docetaxel (Doc) or abiraterone to androgen deprivation therapy (ADT) in men with mCSPC improves survival. Whether the triple combination of ADT, Doc and next gene...

Randomised phase 3 trial of enzalutamide in androgen deprivation therapy (ADT) with radiation therapy for high risk, clinically localized prostate cancer: ENZARAD (ANZUP 1303).

TPS156 Background: Adjuvant ADT with an LHRH analog (LHRHA) given before, during and after radiotherapy (RT) is standard of care for high risk localised prostate cancer (PC). Enzalutamide improves overall survival (OS) in castration-resistant, metastatic prostate cancer. We hypothesized that the addition of enzalutamide to adjuvant ADT and RT will improve outcomes. The aim is to determine the effects of enzalutamide versus a conventional non-steroidal anti-androgen (NSAA) as part of neoadjuvant and adjuvant ADT in men undergoing RT for high risk, localized PC. Methods: DESIGN: Open label, randomised, phase 3 trial including ANZ, USA, UK, Ireland and Europe. ENDPOINTS: OS (primary), cause-specific survival, PSA progression free survival (PFS), clinical PFS, time to subsequent hormonal therapy, time to castration-resistant disease (PCWG2 criteria), metastasis free survival (MFS), adverse events and health-related quality of life (HRQOL). CORRELATIVE OBJECTIVES: identification of prognostic/predictive biomarkers from archival tumour tissue and serial blood samples. SAMPLE SIZE: 800 participants with a minimum follow-up of 5.5 yrs is designed to give 80% power to detect 33% reduction in the hazard of death assuming 5-year survival rate of 76% amongst controls. TREATMENT: Enzalutamide 160mg daily for 24 months versus conventional NSAA for 6 months. All participants receive LHRHA for 24 months, and RT starting about week 16 delivered as 78Gy in 39#, or 46Gy in 23# plus brachytherapy (nodal RT optional for N0, mandatory for N1). ASSESSMENTS: Baseline, then every 8 weeks until year 2, then 3-4 monthly until year 5, 6-monthly until year 7, then annually. Imaging with CT/MRI and bone scan at baseline, PSA progression, then 6 monthly until re-initiation of ADT, when PCWG2 criteria for CRPC are met and then 3 monthly until evidence of metastases. 623 participants recruited from 61 sites as of 16 October 2017. ENZARAD is an investigator-initiated cooperative group trial led by ANZUP Cancer Trials Group with funds and product from Astellas. Clinical trial information: NCT02446444.

Randomized trial of enzalutamide versus bicalutamide in combination with androgen deprivation in metastatic hormone sensitive prostate cancer: A Prostate Cancer Clinical Trials Consortium trial.

190 Background: Addition of abiraterone or docetaxel has overall survival (OS) benefit in metastatic hormone sensitive prostate cancer (mHSPC). The clinical outcomes with early enzalutamide in mHSPC are unknown. We compared the combinations of enzalutamide (Arm A) or bicalutamide (Arm B) each with LHRH analogue therapy in mHSPC. Methods: The primary endpoint was PSA nadir &lt; 4 ng/ml after 7 months of therapy, as this has been recognized as a powerful surrogate for overall survival (OS) outcomes. A minimum of 29 African American (AA) patients were required to be enrolled to evaluate the effect of race on the primary endpoint. Secondary endpoints were toxicities, biochemical and radiologic progression free survival (PFS), and OS. Stratification was by presence of bone pain and race; AA or other. PSA was monitored monthly for first 7 months and then every 3 months. The target sample size was 82 evaluable patients but the study was stopped when early abiraterone showed OS benefit in mHSPC. Metastatic site biopsies were mandatory pretherapy and optional post therapy. Results: 71 men; 29 black, 41 white and 1 Asian were enrolled. The median age was 67 years (range 46-87 years) and median baseline PSA was 56.3 ng/ml in Arm A (4.2-10,431 ng/ml) and 60 (4.9-12,030 ng/ml) in Arm B. 27 pts (38.5%) had bone pain and 13 had visceral metastases. No seizures were noted in either arm. Grade 3+ AE’s on Arm A were: Hypertension (13%), infection (7%), and Snycope (7%) and on Arm B were: Hypertension (21%), Fatigue (7%), and Hematuria (7%). By intent to treat PSA nadir &lt; 4ng/ml at month 7 was achieved in 96.3% pts in arm A and 66.7% pts in arm B and in 71.7% of AA men and 89.7% of Caucasians. The 6-month PSA remission duration rates after month 7 on Arms A and B were 86% and 79%, respectively. 53 (75%) biopsy samples had tumor tissue available. Tmprss2-Erg fusion gene expression and androgen biosynthetic enzyme levels were determined in metastatic biopsies and will be correlated with clinical endpoints. Conclusions: Early enzalutamide use in mHSPC has the potential to improve PSA remission rates and subsequently improve PFS and OS outcomes. Clinical trial information: NCT02058706.

A phase II trial of enzalutamide in patients with androgen receptor positive (AR+) ovarian, primary peritoneal or fallopian tube cancer and one, two, or three prior therapies.

TPS5610 Background: Approximately 75% of women with epithelial ovarian cancer (OC) present with advanced disease. Most of these women will ultimately recur and require life-long treatment for their cancer. Well tolerated therapies for treatment in the recurrent setting are needed. The AR is expressed in greater than 60% of cases of OC and is more prevalent than the estrogen or progesterone receptor. All past clinical studies of AR inhibition in OC have focused on unselected populations of heavily pretreated women; however preclinical data suggests that AR expression decreases in OC cells with increasing lines of therapy. Enzalutamide is a small molecule androgen receptor-antagonist that is FDA approved for treatment of prostate cancer and is currently being investigated as treatment for breast and ovarian cancer. Methods: This is a phase II, single-institution trial of enzalutamide 160mg po QD in patients with AR+ ovarian, fallopian tube or primary peritoneal cancer. Eligible patients must be found to have greater than or equal to 5% AR staining by IHC on FFPE tumor tissue and been treated with only 1,2 or 3 prior cytotoxic therapies. Patients must have RECIST 1.1 defined measurable disease. Enrolled patients are treated with enzalutamide until progression of disease or unacceptable toxicity. The primary endpoint is to estimate the proportion of women who achieve a complete or partial response by RECIST 1.1 criteria or survive progression free for at least 6 months. Secondary objectives include the retrieval of optional tumor biopsies at time of progression to evaluate the effect of enzalutamide on AR expression and to observe the effect of enzalutamide on serum testosterone and estradiol levels. This study will enroll 58 patients at Memorial Sloan Kettering Cancer Center and its regional sites. The study utilizes a safety lead-in phase and a two-stage design. The first patient enrolled in April 2015. The safety lead-in phase has been completed. The prespecified activity goal for the first stage was met; second stage accrual began in October 2016. Thus far, 35 patients have initiated treatment. Clinical trial information: NCT01974765.

Randomised phase III trial of enzalutamide in androgen deprivation therapy (ADT) with radiation therapy for clinically localised, high risk, or node-positive prostate cancer: ENZARAD (ANZUP 1303).

TPS5096 Background: Adjuvant ADT with an LHRH analog (LHRHA) given before, during and after radiotherapy (RT) is standard of care for high risk localised prostate cancer (PC). Enzalutamide is more effective in metastatic disease than conventional non-steroidal anti-androgens (NSAA). We hypothesize that addition of enzalutamide to adjuvant ADT and RT will improve outcomes. The aim is to determine the efficacy of enzalutamide compared with NSAA as part of adjuvant ADT with LHRHA in men planned for RT for localized high risk or node-positive PC. Methods: DESIGN: Open label, randomised, phase 3 trial including ANZ, USA, UK, Ireland and Europe. ENDPOINTS: OS (primary), cause-specific survival, PSA PFS, clinical PFS, time to subsequent hormonal therapy, time to castration-resistant disease (PCWG2 criteria), metastasis free survival, adverse events and HRQOL. Tertiary objectives: identification of prognostic/predictive biomarkers from archival tumour tissue and 4 serial fasting bloods. 800 target participants with 5.5 yrs minimum follow-up. 80% power to detect 33% reduction in the hazard of death assuming 5-year survival rate of 76% amongst controls. TREATMENT: Participants are randomised 1:1 to enzalutamide 160mg daily for 24 months versus conventional NSAA for 6 months. All participants receive LHRHA for 24 months and RT starting after week 16. RT delivered as 78Gy in 39 Fx or 46Gy in 23 Fx plus brachytherapy (nodal RT optional for N0, mandatory for N1). ASSESSMENTS: Baseline, then every 8 weeks until year 2, then 3-4 monthly until year 5, 6-monthly until year 7, then annually. CT/MRI and bone scan at baseline, PSA progression, 6 monthly until re-initiation of ADT, when PCWG2 criteria for CRPC are met and then 3 monthly until evidence of metastases. As of 1st February 2017, 55 of 67 sites open with 398 patients recruited. EORTC sites expected to open from Quarter 1 2017. ENZARAD is an investigator-initiated cooperative group trial led by ANZUP Cancer Trials Group with funds and product from Astellas. ANZUP is supported by Cancer Australia and previously CI NSW. ClinicalTrials.gov: NCT02446444, ANZCTR: ACTRN12614000126617 Clinical trial information: NCT02446444.

Randomised phase 3 trial of enzalutamide in first-line androgen deprivation therapy for metastatic prostate cancer: The ANZUP ENZAMET Trial (ANZUP 1304).

TPS5077 Background: Androgen deprivation therapy (ADT) with a luteinising hormone releasing hormone analogue (LHRHA) or surgical castration, either alone or combined with conventional non-steroidal...

A phase I/II trial of enzalutamide plus the glucocorticoid receptor antagonist mifepristone for patients with metastatic castration-resistant prostate cancer (mCRPC).

TPS5091Background: Metastatic castration-resistant prostate cancer (mCRPC) is a lethal disease with limited therapeutic options. AR targeting therapies such as enzalutamide (Enz) are often effectiv...

Randomised phase 3 trial of enzalutamide in androgen deprivation therapy (ADT) with radiation therapy for clinically localised high-risk or node-positive prostate cancer: ENZARAD (ANZUP 1303).

TPS5086Background: Adjuvant ADT with an LHRH analog (LHRHA) given before during and after radiotherapy (RT) is standard of care for high risk localised prostate cancer (PC). Enzalutamide is more ef...

Phase II trial of enzalutamide in patients with androgen receptor positive (AR+) ovarian, primary peritoneal or fallopian tube cancer and one, two or three prior therapies.

TPS5602Background: Approximately 75% of women with epithelial ovarian cancer (OC) present with advanced disease. The majority of these women will ultimately recur and require life-long treatment fo...