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

NCT07123103 | Recruiting Phase 1 FDA Drug

• 1 other identifier: XB371-101
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 9

Brief Summary

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.

Conditions

Solid Tumors

Keywords

Advanced Solid Tumors; Metastatic Solid Tumors

Outcome Measures

Primary Outcomes (2)

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

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

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

  Up to approximately 7 months

Secondary Outcomes (8)

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

  Up to approximately 7 months

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

  Up to approximately 7 months

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

  Up to approximately 7 months

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

  Up to approximately 7 months

• Number of Participants with Antidrug Antibodies to XB371

  Up to approximately 7 months

Study Arms (3)

Dose-escalation Cohorts

EXPERIMENTAL

Participants will receive escalating doses of XB371 every 3 weeks of a 21-day cycle (alternate schedules may be evaluated) until meeting the criteria for treatment discontinuation.

Drug: XB371

Dose-expansion Cohorts: Part A

EXPERIMENTAL

Participants with Tumor Type 1 (tumor type will be selected based on available data) will be randomized to receive XB371 at one of two recommended dose levels (recommended dose \[RD\]-1 or RD-2) every 3 weeks of a 21-day cycle (alternate schedules may be evaluated) until meeting the criteria for treatment discontinuation.

Drug: XB371

Dose-expansion Cohorts: Part B

EXPERIMENTAL

Participants with Tumor Type 2 (tumor type will be selected based on available data) will receive XB371 at the recommended dose level every 3 weeks of a 21-day cycle (alternate schedules may be evaluated) until meeting the criteria for treatment discontinuation.

Drug: XB371

Interventions

XB371 DRUG

Intravenous (IV) infusion.

Dose-escalation Cohorts; Dose-expansion Cohorts: Part A; Dose-expansion Cohorts: Part B

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• Exelixis: lead

Study Sites (9)

Exelixis Clinical Site #5

Rogers, Arkansas, 72758, United States

RECRUITING

Exelixis Clinical Site #9

Los Angeles, California, 90033, United States

RECRUITING

Exelixis Clinical Site #6

Washington D.C., District of Columbia, 20057, United States

RECRUITING

Exelixis Clinical Site #4

Orlando, Florida, 32827, United States

RECRUITING

Exelixis Clinical Site #3

Grand Rapids, Michigan, 49546, United States

RECRUITING

Exelixis Clinical Site #7

New Brunswick, New Jersey, 08901, United States

RECRUITING

Exelixis Clinical Site #2

Huntersville, North Carolina, 28078, United States

RECRUITING

Exelixis Clinical Site #8

Houston, Texas, 77030, United States

RECRUITING

Exelixis Clinical Site #1

San Antonio, Texas, 78229, United States

RECRUITING

Study Officials

• Medical Director

  Exelixis

  STUDY DIRECTOR

Central Study Contacts

Exelixis Clinical Trials

CONTACT

1-888-EXELIXIS (888-393-5494); druginfo@exelixis.com

Backup or International

CONTACT

1-650-837-7400

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SEQUENTIAL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 8, 2025
• First Posted: August 14, 2025
• Study Start: August 18, 2025
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): February 1, 2028
• Last Updated: February 17, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (9)