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NCT Number: NCT07361562

A Study of a Selective ERBB2 Inhibitor (CGT4255), in Patients With Advanced Solid Tumors

This is an open-label, phase 1/1b study evaluating the safety, tolerability, pharmacokinetic (what the body does to the drug), pharmacodynamic (what the drug does to the body), and antitumor activity of CGT4255 in adult participants with advanced solid tumors with ERBB2 alterations or HER2 overexpression.

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Key information

Conditions

Advanced Solid Tumor, Adult Bronchial Neoplasms Carcinoma, Bronchogenic Carcinoma, Non-Small-Cell Lung ERBB2 Altered Breast Cancer ERBB2 Gene Amplification HER2 HER2 Overexpression Lung Diseases Lung Neoplasms Neoplasms Neoplasms by Site Non-small Cell Lung Cancer Respiratory Tract Diseases Respiratory Tract Neoplasms Thoracic Neoplasms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

START Midwest, Grand Rapids, Michigan, United States

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Have histologically confirmed diagnosis of:
  • Part A: Locally advanced, metastatic, and/or unresectable solid tumor with documented ERBB2-activating alteration or NRG1 gene fusion in blood and/or tumor or HER2 overexpression in tumor
  • Part B: Locally advanced, metastatic, and/or unresectable NSCLC with documented ERBB2 mutation in blood and/or tumor
  • Part C: Locally advanced, metastatic and/or unresectable breast cancer with documented ERBB2 mutation in blood and/or tumor or HER overexpression in tumor
  • Have measurable disease per RECIST v1.1.
  • Eastern Cooperative Oncology Group (ECOG) Performance Status 0 to 1 for Part A. For Parts B and C, ECOG Performance Status must be 0 to 2.
  • Have clinically acceptable local laboratory screening results (clinical chemistry and hematology) within certain limits.

Exclusion criteria

  • Received small molecule chemotherapy or anticancer therapies or radiotherapy within certain timeframes before first dose of study drug.
  • Major surgeries (eg, craniotomy and thoracotomy) within 4 weeks of the first dose of study drug.
  • Treatment with palliative focal radiotherapy (cranial or extracranial) (eg, stereotactic radiosurgery or intensity-modulated radiation therapy) ≤2 weeks before the first dose of study drug; treatment with whole-brain radiotherapy ≤4 weeks before the first dose of study drug.
  • Clinically significant cardiac disease.
  • Resolution of toxicities from prior therapy to ≤Grade 1 (or baseline), including resolution of clinically significant laboratory abnormalities, before the first dose of study drug.
  • Restrictions on use of corticosteroid use to manage neurologic symptoms in different parts of the study.

Treatment and study plan

CGT4255

Drug

CGT4255 Daily Oral Administration

Primary outcomes

  1. Incidence and grade of Adverse Events (AEs) and Serious Adverse Events (SAEs) [Part A]

    Time frame: Approximately 12 months

    • Incidence and grade of Adverse Events (AEs) and Serious Adverse Events (SAEs) and AEs leading to dose modifications and dose limiting toxicities (DLTs) to determine the maximum tolerated dose (MTD) or the maximum evaluated dose (MED) in participants with ERBB2-altered advanced solid tumors

  2. Overall Response Rate [Part B and Part C]

    Time frame: Approximately 6 months

    Overall Response Rate (ORR), determined by confirmed CR + PR of all lesions (intracranial and extracranial), based on Investigator assessment using the whole-body RECIST v1.1 in participants with ERBB2-mutated NSCLC with Brain Metastases (BM) and in participants with ERBB2-mutated or HER2-positive breast cancer with BM ± leptomeningeal disease (LMD)

Secondary outcomes

  1. Incidence and grade of Adverse Events (AEs) and Serious Adverse Events (SAEs) [Part B and C]

    Time frame: Approximately 7 months

    Incidence and grade of Adverse Events (AEs), Serious Adverse Events (SAEs) and AEs leading to dose modification in participants with ERBB2-mutated NSCLC with Brain Metastases (BM) and in participants with ERBB2-mutated or HER2-positive breast cancer with BM ± leptomeningeal disease (LMD)

  2. Pharmacokinetics [Part A]

    Time frame: Approximately 28 days

    Area under the concentration-time curve (AUC) in participants with ERBB2 altered advanced solid tumors

  3. Pharmacokinetics [Part A]

    Time frame: Approximately 28 days

    Maximum observed concentration (Cmax) in participants with ERBB2 altered advanced solid tumors

  4. Pharmacokinetics [Part A]

    Time frame: Approximately 28 days

    Observed concentration at pre-dose (Ctrough)

  5. Pharmacokinetics [Part A)

    Time frame: Approximately 28 days

    Time to measure concentration (Tmax)

  6. Disease Response [Part A]

    Time frame: Approximately 6 months

    Overall objective response rate (ORR), as determined by confirmed complete response (CR) + confirmed partial response (PR) of all lesions (intracranial and extracranial) based on Investigator assessment using whole-body Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1)

  7. Disease Response [Part A]

    Time frame: Approximately 6 months

    Disease control rate (DCR), as determined by overall confirmed CR + confirmed PR + stable disease (SD) based on Investigator assessment using whole-body RECIST v1.1

  8. Disease Response [Part B and Part C]

    Time frame: Approximately 6 months

    Disease Control Rate (DCR), determined by overall confirmed CR + confirmed PR +SD based on Investigator assessment using whole body RECIST v1.1

  9. Disease Response [Part B and Part C]

    Time frame: Approximately 6 months

    Duration of Response (DOR), defined as time from first confirmed response (CR or PR) to the date of progressive disease (PD) or death from any cause, whichever occurs earlier

  10. Disease Response [Part B and Part C]

    Time frame: Approximately 6 months

    Progression- free survival (PFS), defined as the time from the date of the first dose of study drug (Part B run-in and Part C)/ randomization (Part B randomized cohort) until the date of PD, based on Investigator assessment using whole body RECIST v1.1, or death from any cause, whichever comes earlier

Study contacts

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

Cogent Biosciences, Inc

CONTACT

[email protected]

617-945-5576

Sponsors and collaborators

Lead sponsor

Cogent Biosciences, Inc.

Industry

Registry information

Official study title

A Study of a Selective ERBB2 Inhibitor, CGT4255, in Patients With Advanced Solid Tumors With ERBB2 Genetic Alterations or HER2 Overexpression

Important dates

Study start
2025
Primary completion
2028
Study completion
2028
First posted
Jan 23, 2026
Registry last updated
Feb 27, 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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