NCT06993844 · Ensem Therapeutics
Phase 1/2 Study of ETX-636 in Participants With Advanced Solid Tumors
What this study is about
Phase 1/2, where both patients and doctors know the treatment given study of ETX-636 in participants with advanced solid tumors
View original scientific description
Phase 1/2, open-label study of ETX-636 in participants with advanced solid tumors
Interventions
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.
Primary outcome measures
Evaluate Safety and Tolerability of ETX-636 monotherapy in Part A and ETX-636 plus fulvestrant combination therapy in Part B
Time frame: First 28 days of treatment
Proportion of participants who experience at least 1 Dose Limiting Toxicity (DLT)
Evaluate Safety and Tolerability of ETX-636 monotherapy in Part A and ETX-636 plus fulvestrant combination therapy in Part B
Time frame: Average of 6 months
Incidence of AEs, treatment discontinuations due to AEs, changes from baseline in laboratory assessments, ECGs and vital signs.
Select the Recommended Phase 2 Dose(s) (RP2D) in Part B to be further explored in Part C (combination therapy expansion)
Time frame: Average of 6 months
Safety Parameters as described for primary outcomes
Evaluate efficacy of ETX-636 plus fulvestrant combination therapy at the RP2D(s) in Part C
Time frame: Average of 6 months
ORR and CBR according to RECIST v1.1
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Metastatic or locally advanced and unresectable solid tumor that has progressed on or after at least one available therapy.
- Tumor harboring an activating PIK3CA mutation detected in either tumor tissue or ctDNA.
- At least 1 measurable lesion or evaluable disease per RECIST v1.1.
- An ECOG performance status score of 0 or 1.
- Adequate organ function. Additional key inclusion criterion for Parts B and C: \- Confirmed metastatic or locally advanced HR+/HER2- breast cancer not amenable to surgical resection with curative intent and must have received at least 1 prior CDK4/6 inhibitor and at least 1 prior anti-estrogen therapy. Key
Exclusion criteria
- Has history (within ≤2 years before screening) of a solid tumor or hematological malignancy that is histologically distinct from the cancers being studied.
- Has symptomatic brain or spinal metastases or a known or suspected history of untreated or uncontrolled central nervous system (CNS) involvement.
Where
- Newport Beach, California
- San Francisco, California
- New Haven, Connecticut
- Boston, Massachusetts
- Huntersville, North Carolina
- Houston, Texas
- San Antonio, Texas
- Fairfax, Virginia
- Seattle, Washington
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 23, 2026 · Source of record for eligibility and locations