ESSA PHARMA INC. Masofaniten is a first-in-class N-terminal domain androgen receptor ('AR') inhibitor that suppresses androgen activity through a novel mechanism of action and is being developed for the treatment of prostate cancer. The poster presentation is available on the 'Publications' section of the Company's website at www.essapharma.com.
'The maturing data from the Phase 1 dose escalation study evaluating masofaniten in combination with enzalutamide continue to demonstrate that the combination is well tolerated, accompanied by deep and durable reductions in circulating prostate-specific antigen ('PSA') levels. While the data are still immature, the durability of the PSA responses is encouraging with a median time to PSA progression currently at 16.6 months. The Phase 2 dose expansion head-to-head portion of the study is underway and is designed to evaluate the proportion of patients with a PSA decline on combination therapy compared to single agent enzalutamide,' said
Poster presentation details
Title: Phase 1/2 trial of oral EPI-7386 (masofaniten) in combination with enzalutamide (Enz) compared to Enz alone in patients with metastatic castration-resistant prostate cancer (mCRPC): Phase 1 (P1) results and phase 2 (P2) design.
Presenting Author:
Abstract #: 141
Date and time:
Data summary: This Phase 1/2 multicenter, open-label clinical trial enrolled patients with mCRPC who have received androgen deprivation therapy and who are naive to second-generation antiandrogens but may have been treated previously with one line of prior chemotherapy in the metastatic hormone-sensitive prostate cancer setting. The data presented today include 18 patients across four cohorts in the Phase 1 dose escalation portion of the study. Masofaniten has no effect on enzalutamide exposure, thus allowing the use of full dose per label (160mg) of enzalutamide in combination. Enzalutamide reduces masofaniten exposure but twice daily dosing of masofaniten appears to mitigate the reduction and maintains clinically relevant drug exposures.
In patients evaluable for safety (n=18), masofaniten combined with enzalutamide, continues to be well-tolerated at the dose levels tested through 25 cycles of dosing in some patients. Most frequent adverse events were Grades 1 and 2, related to either AR inhibition or gastrointestinal tract irritation. In Cohort 4, one patient experienced a Grade 3 rash, which was observed immediately following administration of masofaniten combined with enzalutamide and deemed probably related, resulting in the expansion of the cohort from four to seven patients. No additional dose-limiting toxicities (DLTs) were observed, therefore the maximum tolerated dose (MTD) was not reached. The recommended Phase 2 combination doses (RP2CDs) were identified as masofaniten 600 mg twice daily (BID) in combination with enzalutamide 160 mg once daily (QD).
In the patients evaluable for efficacy (n=16), rapid, deep and durable reductions in PSA were observed, regardless of previous chemotherapy status, including in patients who received lower than the full dose of enzalutamide (120 mg). Across all dose cohorts, 88% of patients (14 of 16) achieved PSA50, 81% of patients (13 of 16) achieved PSA90, 69% of patients (11 of 16) achieved PSA90 in less than 90 days, and 63% of patients (10 of 16) achieved PSA
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