American Association for Cancer Research
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Supplementary Table 2 from A Phase Ib/IIa Study of the Pan-BET Inhibitor ZEN-3694 in Combination with Enzalutamide in Patients with Metastatic Castration-resistant Prostate Cancer

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posted on 2023-03-31, 22:04 authored by Rahul R. Aggarwal, Michael T. Schweizer, David M. Nanus, Allan J. Pantuck, Elisabeth I. Heath, Eric Campeau, Sarah Attwell, Karen Norek, Margo Snyder, Lisa Bauman, Sanjay Lakhotia, Felix Y. Feng, Eric J. Small, Wassim Abida, Joshi J. Alumkal

Supplementary Table 2


Zenith Epigenetics

Department of Defense Prostate Cancer Research Program

NIH NCI Cancer Center Support grant

Prostate Cancer SPORE

Prostate Cancer Foundation



ZEN-3694 is a bromodomain extraterminal inhibitor (BETi) with activity in androgen-signaling inhibitor (ASI)-resistant models. The safety and efficacy of ZEN-3694 plus enzalutamide was evaluated in a phase Ib/IIa study in metastatic castration-resistant prostate cancer (mCRPC). Patients had progressive mCRPC with prior resistance to abiraterone and/or enzalutamide. 3+3 dose escalation was followed by dose expansion in parallel cohorts (ZEN-3694 at 48 and 96 mg orally once daily, respectively). Seventy-five patients were enrolled (N = 26 and 14 in dose expansion at low- and high-dose ZEN-3694, respectively). Thirty (40.0%) patients were resistant to abiraterone, 34 (45.3%) to enzalutamide, and 11 (14.7%) to both. ZEN-3694 dosing ranged from 36 to 144 mg daily without reaching an MTD. Fourteen patients (18.7%) experienced grade ≥3 toxicities, including three patients with grade 3 thrombocytopenia (4%). An exposure-dependent decrease in whole-blood RNA expression of BETi targets was observed (up to fourfold mean difference at 4 hours post–ZEN-3694 dose; P ≤ 0.0001). The median radiographic progression-free survival (rPFS) was 9.0 months [95% confidence interval (CI), 4.6–12.9] and composite median radiographic or clinical progression-free survival (PFS) was 5.5 months (95% CI, 4.0–7.8). Median duration of treatment was 3.5 months (range, 0–34.7+). Lower androgen receptor (AR) transcriptional activity in baseline tumor biopsies was associated with longer rPFS (median rPFS 10.4 vs. 4.3 months). ZEN-3694 plus enzalutamide demonstrated acceptable tolerability and potential efficacy in patients with ASI-resistant mCRPC. Further prospective study is warranted including in mCRPC harboring low AR transcriptional activity.

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