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

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

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

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
75

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • 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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
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

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
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

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Exelixis

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • 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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
May 31, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 23, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 23, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 30, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 14, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 12, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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.

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