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NCT Number: NCT07284186

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

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.

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Key information

Conditions

Esophageal Squamous Cell Carcinoma Adenocarcinoma Adenocarcinoma Of Esophagus Advanced Solid Tumor Bronchial Neoplasms Carcinoma Carcinoma, Bronchogenic Carcinoma, Non-Small-Cell Lung Carcinoma, Squamous Cell Digestive System Diseases Digestive System Neoplasms Esophageal Adenocarcinoma Esophageal Diseases Esophageal Neoplasms Gastric Adenocarcinoma Gastric Squamous Cell Carcinoma Gastroesophageal Junction (GEJ) Adenocarcinoma Gastroesophageal Junction Squamous Cell Carcinoma Gastrointestinal Diseases Gastrointestinal Neoplasms Head and Neck Neoplasms Lung Diseases Lung Neoplasms Metastatic Solid Tumor Neoplasm Metastasis Neoplasms Neoplasms by Histologic Type Neoplasms by Site Neoplasms, Glandular and Epithelial Neoplasms, Squamous Cell Neoplastic Processes Non-small Cell Lung Carcinoma Pathologic Processes Pathological Conditions, Signs and Symptoms Respiratory Tract Diseases Respiratory Tract Neoplasms SMARCA4 Mutation Thoracic Neoplasms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

Research Site, Scottsdale, Arizona, United States

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Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

PLX-61639

Drug

Orally available degrader of SMARCA2

Primary outcomes

  1. Treatment Emergent Adverse Events

    Time frame: From enrollment to 28 days after the last dose of PLX-61639

  2. Dose-Limiting Toxicities

    Time frame: From enrollment to 28 days after first dose of PLX-61639

Secondary outcomes

  1. Dose reductions due to Adverse Events

    Time frame: From Day 1 to the end of PLX-61639 treatment, an average of 1 year

  2. Study treatment discontinuations for reasons other than disease progression

    Time frame: From Day 1 to the end of PLX-61639 treatment, an average of 1 year

  3. Pharmacokinetics of PLX-61639: Cmax

    Time frame: From Day 1 to Day 15 of Cycle 1 (Part 1 only) (each cycle is 28 days)

  4. Pharmacokinetics of PLX-61639: Tmax

    Time frame: From Day 1 to Day 15 of Cycle 1 (Part 1 only) (each cycle is 28 days)

  5. Pharmacokinetics of PLX-61639: AUC0-last

    Time frame: From Day 1 to Day 16 of Cycle 1 (Part 1 only) (each cycle is 28 days)

  6. Radiographic response to PLX-61639

    Time frame: From Day 1 to the end of PLX-61639 treatment, an average of 1 year

  7. Time to response (TTR) to PLX-61639

    Time frame: From Day 1 to achievement of partial or complete response, up to 24 weeks

  8. Duration of response (DoR) to PLX-61639

    Time frame: From first documented partial or complete response to disease progression or death, an average of 1 year

  9. Progression Free Survival (PFS) of PLX-61639

    Time frame: From Day 1 to disease progression or death, an average of 1 year

Study contacts

Contact information is provided by the study sponsor or research team.

Clinical Operations

CONTACT

[email protected]

619-631-3091

Sponsors and collaborators

Lead sponsor

Plexium, Inc.

Industry

Registry information

Official study title

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

Important dates

Study start
2025
Primary completion
2029
Study completion
2030
First posted
Dec 16, 2025
Registry last updated
Jun 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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