On October 21, 2023 ESSA Pharma Inc. ("ESSA", or the "Company") (NASDAQ: EPIX), a clinical-stage pharmaceutical company focused on developing novel therapies for the treatment of prostate cancer, reported the presentation of updated dose escalation data from its Phase 1/2 study evaluating masofaniten (formerly EPI-7386) in combination with enzalutamide at the European Society of Medical Oncology (ESMO) (Free ESMO Whitepaper) 2023 Congress, taking place October 20-24, 2023, in Madrid, Spain (Press release, ESSA, OCT 21, 2023, View Source [SID1234636227]). 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 ESMO (Free ESMO Whitepaper) Digital Program and in the "Publications" section of the Company’s website at www.essapharma.com.
Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:
Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing
Schedule Your 30 min Free Demo!
"The dose escalation data presented at ESMO (Free ESMO Whitepaper) this year continue to demonstrate that the combination of masofaniten and enzalutamide is well tolerated and results in deep and durable reductions in prostrate-specific antigen ("PSA") in patients with metastatic castration-resistant prostate cancer ("mCRPC")," said David Parkinson, MD, President and CEO of ESSA. "While the data for patients in cohort four are not yet mature, we are highly encouraged by the PSA responses seen thus far in the cohort and in the study as a whole. We look forward to further elucidating the potential clinical benefit of this combination in the randomized Phase 2 portion of the study which is currently underway."
Poster presentation details:
Title: Phase 1/2 Trial of Oral EPI-7386 (masofaniten) in Combination with Enzalutamide (Enz) Compared with Enz Alone in Subjects with Metastatic Castration-Resistant Prostate Cancer (mCRPC): Current Phase 1 (P1) results
Presenting Author: Andrew Laccetti, MD, MS, Memorial Sloan Kettering Cancer Center
Abstract # 1813P
Date: Sunday, October 22, 2023
Data summary: This Phase 1/2 multicenter, open-label clinical trial is enrolling patients with mCRPC who have received androgen deprivation therapy and who are naïve 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 are from the first four cohorts of patients 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 doses tested through 21 cycles of dosing in some patients. Most frequent adverse events were Grade 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.
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). In the first three cohorts, 90% of patients (9 of 10) achieved PSA50 and PSA90, 80% of patients (8 of 10) achieved PSA90 in less than 90 days, and 70% of patients (7 of 10) achieved PSA <0.2mg/mL. Across all dose cohorts including patients in the recently enrolled cohort four, 88% of patients (14 of 16) achieved PSA50, 69% of patients (11 of 16) achieved PSA90, 63% of patients (10 of 16) achieved PSA90 in less than 90 days, and 56% of patients (9 of 16) achieved PSA <0.2mg/mL. The randomized Phase 2 dose expansion portion of the study is currently enrolling.
About Masofaniten
Masofaniten (formerly known as EPI-7386) is a first-in-class investigational, highly selective, oral, small molecule inhibitor of the N-terminal domain ("NTD") of the androgen receptor ("AR"). Masofaniten’s unique mechanism of action disrupts the AR signaling pathway, the primary pathway that drives prostate cancer growth, by selectively binding to the NTD, a region of the AR that is not currently targeted by other therapies. Masofaniten is currently being studied in an open-label, randomized Phase 2 clinical trial (NCT05075577) in combination with enzalutamide in patients with metastatic castration-resistant prostate cancer (mCRPC) naïve to second-generation antiandrogens. ESSA is also conducting a Phase 1 monotherapy study (NCT04421222) in patients with mCRPC whose tumors have progressed on standard-of-care therapies. The U.S. Food and Drug Administration has granted Fast Track designation to masofaniten for the treatment of adult male patients with mCRPC resistant to standard-of-care treatment. ESSA retains all rights to masofaniten worldwide.