A Study of XB628 in Participants With Recurrent Advanced or Metastatic Solid Tumors

May 12, 2026 updated by: Exelixis

A Phase 1 Study of XB628 in Participants With Recurrent Advanced or Metastatic Solid Tumors

This is a phase 1, first-in-human, open-label, dose-escalation study of XB628, a first-in-class bispecific antibody natural killer (NK) cell engager that targets NK group 2 member A (NKG2A), an inhibitory receptor on NK cells, and programmed cell death-ligand 1 (PD-L1).

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

This study consists of a Dose-Escalation Stage. The Dose-Escalation Stage is designed to determine the maximum tolerated dose (MTD) and/or recommended dosage(s) for expansion (RDE[s]) of XB628 as a single agent.

Study Type

Interventional

Enrollment (Estimated)

75

Phase

  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

  • Name: Exelixis Clinical Trials
  • Phone Number: 1-888-EXELIXIS (888-393-5494)
  • Email: druginfo@exelixis.com

Study Contact Backup

  • Name: Backup or International
  • Phone Number: 650-837-7400

Study Locations

  • United States
    • California
      • San Francisco, California, United States, 94158
        • Recruiting
        • Exelixis Clinical Site #5
    • Connecticut
      • New Haven, Connecticut, United States, 06520
        • Recruiting
        • Exelixis Clinical Site #4
    • Florida
      • Tampa, Florida, United States, 33612
        • Recruiting
        • Exelixis Clinical Site #8
    • Massachusetts
      • Boston, Massachusetts, United States, 02114
        • Recruiting
        • Exelixis Clinical Site #10
      • Boston, Massachusetts, United States, 02114
        • Recruiting
        • Exelixis Clinical Site #11
    • Missouri
      • St Louis, Missouri, United States, 63108
        • Recruiting
        • Exelixis Clinical Site #6
    • New York
      • New York, New York, United States, 10029
        • Recruiting
        • Exelixis Clinical Site #7
    • North Carolina
      • Hickory, North Carolina, United States, 28602
        • Recruiting
        • Exelixis Clinical Site #1
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Recruiting
        • Exelixis Clinical Site #3
    • Texas
      • Houston, Texas, United States, 77030
        • Recruiting
        • Exelixis Clinical Site #9
      • San Antonio, Texas, United States, 78229
        • Recruiting
        • Exelixis Clinical Site #2

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.
  • Minimum life expectancy of ≥ 12 weeks.
  • Have a recurrent advanced or metastatic solid tumor that is histologically or cytologically confirmed.
  • Adequate organ and marrow function.
  • Not amenable to curative treatment with surgery or radiation.
  • Received at least 1 line of prior systemic anticancer therapy in the recurrent or metastatic setting.
  • Acceptable alternative therapy was received, refused, intolerable, or no longer effective.
  • Capable of understanding and complying with the protocol requirements and provide signed informed consent according to the protocol and local requirements.

Exclusion Criteria

  • Primary brain tumors or known active brain metastases.
  • Major surgery (eg, gastrointestinal surgery, removal or biopsy of brain metastasis) within 4 weeks before the first dose of study treatment.
  • Received radiation therapy within 1 week before the first dose of study treatment or clinically relevant ongoing complications from prior radiation therapy.
  • Received prior therapy targeting NK cells (eg, monalizumab).
  • A woman of childbearing potential has a positive serum pregnancy test within 7 days prior to study treatment.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: XB628
Group(s) of participants with recurrent advanced or metastatic solid tumors will receive escalating dose levels doses of XB628.
Biological: XB628
Intravenous infusion(s)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Number of Participants with Dose Limiting Toxicities (DLTs)
Time Frame: 21 days
21 days
Number of Participants with Serious Adverse Events (SAEs), Treatment-emergent Adverse Events (TEAEs), and Adverse Events (AEs) Leading to Dose Withholding, Treatment Discontinuation, or Death
Time Frame: 27 months
27 months

Secondary Outcome Measures

Outcome Measure
Time Frame
Area Under the Concentration-time Curve (AUC) of XB628
Time Frame: 25 months
25 months
Maximum Plasma Concentration (Cmax) of XB628
Time Frame: 25 months
25 months
Time to Maximum Concentration (Tmax) of XB628
Time Frame: 25 months
25 months
Elimination Half-life (T1/2) of XB628
Time Frame: 25 months
25 months
Apparent Clearance (CL/F) of XB628
Time Frame: 25 months
25 months
Trough Concentration (Ctrough) of XB628
Time Frame: 25 months
25 months
Number of Participants with Antidrug Antibody (ADA) Response to XB628
Time Frame: 25 months
25 months
Objective Response Rate (ORR)
Time Frame: 27 months
27 months
Duration of Response (DOR)
Time Frame: 27 months
27 months
RDE for XB628
Time Frame: 25 months
25 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Exelixis

Investigators

  • Study Director: Medical Director, Exelixis

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

May 1, 2025

Primary Completion (Estimated)

May 31, 2027

Study Completion (Estimated)

November 30, 2027

Study Registration Dates

First Submitted

April 23, 2025

First Submitted That Met QC Criteria

April 23, 2025

First Posted (Actual)

April 30, 2025

Study Record Updates

Last Update Posted (Actual)

May 14, 2026

Last Update Submitted That Met QC Criteria

May 12, 2026

Last Verified

May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • XB628-101

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Solid Tumor

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Philippines

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe