NCT06993844

Phase 1/2 Study of ETX-636 in Participants With Advanced Solid Tumors

A Phase 1/2, Open-label, First-in-human Study of the Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy of ETX-636, a Pan-mutant-selective PI3Kα Inhibitor, as Monotherapy and in Combination With Other Anticancer Therapies in Participants With Advanced Solid Tumors

• Status: Recruiting
• Phase: Phase 1 / Phase 2
• Study type: Interventional
• Enrollment: 233 (estimated)
• Sponsor: Ensem Therapeutics · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

Phase 1/2, open-label study of ETX-636 in participants with advanced solid tumors

Detailed description

Brief Summary: This is a Phase 1/2, open-label, multicenter, 3-part study to evaluate the safety, tolerability, PK, PD, and preliminary efficacy of ETX-636 in participants with advanced solid tumors harboring a PIK3CA mutation. Part A will evaluate escalating doses of ETX-636 as monotherapy in participants with advanced solid tumors. Part B will evaluate escalating doses of ETX-636 as combination therapy with fixed dose fulvestrant in participants with hormone receptor positive (HR+), HER2 negative (HER2-) locally advanced or metastatic breast cancer. Part C will be a combination therapy expansion in participants with HR+, HER2- locally advanced or metastatic breast cancer. Each study part will include a 28-day screening period, followed by treatment with ETX-636 monotherapy or combination therapy.

Conditions

• Advanced Solid Tumors
• Advanced Breast Cancer

Interventions

Type	Name	Description
DRUG	ETX-636 dose escalation	ETX-636 is a pan-mutant-selective PI3Kα Inhibitor and degrader in the form of an oral tablet that will be taken once per day in 28-day cycles, to evaluate escalating dose levels.
DRUG	ETX-636 dose escalation in combination with fulvestrant	ETX-636 is a pan-mutant-selective PI3Kα Inhibitor and degrader in the form of an oral tablet. ETX-636 will be taken in combination with fulvestrant in 28-day cycles, to evaluate escalating dose levels. EXT-636 is an oral tablet that will be taken once per day. Fulvestrant will be administered as an injection 2 weeks apart in the first 28 days, followed by monthly injections.
DRUG	ETX-636 dose expansion in combination with fulvestrant	ETX-636 is a pan-mutant-selective PI3Kα Inhibitor and degrader in the form of an oral tablet. ETX-636 will be taken in combination with fulvestrant in 28-day cycles, to expand selected dose levels. EXT-636 is an oral tablet that will be taken once per day. Fulvestrant will be administered as an injection 2 weeks apart in the first 28 days, followed by monthly injections.

Timeline

• Start date: 2025-06-10
• Primary completion: 2027-06-30
• Completion: 2027-12-30
• First posted: 2025-05-29
• Last updated: 2026-03-17

Locations

10 sites across 1 country: United States

Regulatory

• FDA-regulated drug study