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NCT Number: NCT07123103

A Study of XB371 Administered in Participants With Locally Advanced or Metastatic Solid Tumors

The primary purpose of the study is to characterize the safety and tolerability of XB371. The dose-escalation cohorts and Part B of the expansion cohorts are non-randomized. Part A of the expansion cohorts is randomized.

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Key information

Conditions

Solid Tumors

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 1

Primary location

Exelixis Clinical Site #5, Rogers, Arkansas, 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:

  • Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.
  • Minimum life expectancy of ≥ 12 weeks.
  • Recurrent locally advanced or metastatic solid tumors.
  • Adequate end organ and bone marrow function.

Key Exclusion Criteria:

  • Primary brain tumors or known active brain metastases, leptomeningeal, or cranial epidural disease.
  • History of interstitial lung disease (ILD) of any grade or history of organizing pneumonia.
  • Has acute ocular infection, acute or chronic ulcerative/cicatricial condition of conjunctiva or cornea.
  • Known history of immunodeficiency virus (HIV) unless specific criteria are met.
  • Active infection with hepatitis C virus (HCV) defined as positive for HCV antibody.
  • Major surgery within 4 weeks before the first dose of study treatment.
  • Received radiation therapy within 2 weeks before the first dose of study treatment.
  • Received prior systemic anticancer therapy including investigational agents within 4 weeks before the first dose of study treatment.

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply.

Treatment and study plan

XB371

Drug

Intravenous (IV) infusion.

Primary outcomes

  1. Number of Participants with a Dose-limiting Toxicity (DLT)

    Time frame: Up to the end of the first cycle (Up to Day 21 of a 21-day cycle)

  2. Number of Participants with a Treatment-emergent Adverse Event (TEAE)

    Time frame: Up to approximately 7 months

Secondary outcomes

  1. Area Under the Plasma Concentration-time Curve (AUC) of XB371, Total Antibody and Unconjugated Belotecan

    Time frame: Up to approximately 7 months

  2. Maximum Observed Plasma Concentration (Cmax) of XB371, Total Antibody and Unconjugated Belotecan

    Time frame: Up to approximately 7 months

  3. Time to Maximum Observed Plasma Concentration (Tmax) of XB371, Total Antibody and Unconjugated Belotecan

    Time frame: Up to approximately 7 months

  4. Trough Observed Plasma Concentration (Ctrough) of XB371, Total Antibody and Unconjugated Belotecan

    Time frame: Up to approximately 7 months

  5. Number of Participants with Antidrug Antibodies to XB371

    Time frame: Up to approximately 7 months

  6. Dose-escalation Cohorts Only: Recommended Dose(s) for Expansion

    Time frame: Through completion of dose-escalation (up to approximately 18 months)

  7. Dose-expansion Cohorts Only: Objective Response Rate as Assessed by the Investigator per Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST v1.1)

    Time frame: Up to approximately 18 months

  8. Dose-expansion Cohorts Only: Duration of Response as Assessed by the Investigator per RECIST v1.1

    Time frame: Up to approximately 18 months

Study contacts

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

Backup or International

CONTACT

1-650-837-7400

Exelixis Clinical Trials

CONTACT

[email protected]

1-888-EXELIXIS (888-393-5494)

Sponsors and collaborators

Lead sponsor

Exelixis

Industry

Registry information

Official study title

A Dose Escalation and Expansion Study of XB371 Administered in Participants With Locally Advanced or Metastatic Solid Tumors

Important dates

Study start
2025
Primary completion
2027
Study completion
2028
First posted
Aug 14, 2025
Registry last updated
Feb 17, 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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