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First-in-Human Study of PLX-61639 in Locally Advanced or Metastatic Solid Tumors

A Phase 1, First-in-Human Study of the SMARCA2 Degrader, PLX-61639, in Patients With SMARCA4-Mutated Locally Advanced or Metastatic Solid Tumors

Who can join

Ages 18 and older · All sexes

Key Inclusion Criteria:

* Participants with locally advanced or metastatic, relapsed/refractory, solid tumors harboring a SMARCA4 loss-of-function mutation that have progressed on, are intolerant of, or not otherwise candidates for available approved therapies
* Adequate liver bone marrow, coagulation, renal, and cardiopulmonary function
* Measurable disease per RECIST 1.1
* ECOG PS of 0 or 1

Key Exclusion Criteria:

* Germline SMARCA4 mutations
* Known SMARCA2 mutation or loss of expression
* Symptomatic CNS disease
* Prior treatment with another SMARCA2-directed therapy
* History of other malignancies
* Clinically significant heart disease
* Uncontrolled hypertension
* Prolongation of QT interval

About the study

A multicenter, single-arm, first-in-human study to investigate the safety, pharmacokinetics, and preliminary antitumor activity of PLX-61639 in participants with locally advanced or metastatic, relapsed/refractory, SMARCA4-deficient solid tumors who are intolerant of or have failed available, approved therapies.

The study will be conducted in 3 parts: dose escalation (Part 1), dose optimization (Part 2), and cohort expansion (Part 3). Each part of the study will consist of a Screening Phase lasting up to 28 days during which participants will be assessed for eligibility, a Treatment Phase beginning on Cycle 1 Day 1 and consisting of consecutive 28-day cycles, an End of Treatment Visit, and a Post-Treatment Follow-Up Phase.

Participants will receive their assigned dose of PLX-61639 administered orally, once daily until progression/relapse, intolerance, death, or withdrawal from study treatment by the Investigator or participant.

What is being tested

• PLX-61639 (drug)

Sponsor: Plexium, Inc. · Participants: 155 · Started: Dec 1, 2025

Contact the study team

• Clinical Operations · Phone: 619-631-3091

Official record on ClinicalTrials.gov — NCT07284186

Locations in the U.S.

Conditions

• Esophageal Squamous Cell Carcinoma
• Metastatic Cancer
• Non-Small Cell Lung Cancer
• Esophageal Adenocarcinoma

From ClinicalTrials.gov, data retrieved Sep 29, 2026. Each study sets its own eligibility; the study team decides who can join.