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XB628

Phase 1

Solid Tumor | Monoclonal antibody | Oncology |Exelixis, Inc.|Last Updated: Jun 24, 2026

Target and mechanism

Molecular targetPD-L1 + NKG2A
Target classBispecific
ModalityMonoclonal antibody

Success Probability

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Market & Valuation

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Trial Design

CONTROLLED
Total Trials1
Total Enrollment303

FDA Designations

No designations recorded

Clinical trial landscape

XB628 · 1 trial · 4 indications

Phase 1 1
NCT06952010A Study of XB628 Alone and in Combination With Zanzalintinib in Participants With Recurrent Advanced or Metastatic Solid TumorsSolid Tumor
RECRUITING303 Analytics
PHASE1RECRUITING
A Study of XB628 Alone and in Combination With Zanzalintinib in Participants With Recurrent Advanced or Metastatic Solid Tumors
Solid TumorUnlock trial analytics

Study Endpoints

Primary Endpoints

Dose Escalation Cohort: Number of Participants with Dose Limiting Toxicities (DLTs)
21 days
Dose Escalation Cohort: Number of Participants With Treatment Emergent Adverse Events (TEAEs)
Up to 27 months
Dose Expansion Cohort: Objective Response Rate (ORR)
Up to 27 months

Secondary Endpoints

Area Under the Concentration-time Curve (AUC) of XB628
25 months
Maximum Plasma Concentration (Cmax) of XB628
25 months
Time to Maximum Concentration (Tmax) of XB628
25 months
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Dose Escalation PhaseEXPERIMENTALParticipants with recurrent advanced or metastatic solid tumors will receive escalating dose levels doses of XB628 as a single agent and in combination with zanzalintinib.
Dose ExpansionEXPERIMENTALParticipants with recurrent advanced or metastatic solid tumors will receive XB628 as a single agent and in combination with zanzalintinib.

Interventions

NameTypeDescription
XB628BIOLOGICALIntravenous infusion(s)
ZanzalintinibDRUGOral tablet(s)
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites11

Key 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...

Countries:United States
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Competitive Landscape -Other Solid Tumors 9 trials (matched to "Solid Tumor")

Recent Changes (Last 90 Days)

MEDIUMJun 24, 2026NCT06952010Enrollment: 75 → 303
MEDIUMJun 24, 2026NCT06952010Enrollment: 75 → 303

Frequently asked questions about XB628

What is XB628 used for?

XB628 is an investigational bispecific monoclonal antibody being studied for the treatment of recurrent advanced or metastatic solid tumors, including immune-sensitive tumors. It is currently in Phase 1 clinical development and is not yet approved by regulatory authorities.

What does XB628 target?

XB628 targets PD-L1 and NKG2A, two proteins involved in immune regulation. By binding to both targets, the bispecific antibody is designed to modulate immune responses against tumor cells. This dual targeting is being evaluated in the context of solid tumor malignancies.

Who is developing XB628?

XB628 is being developed by Exelixis, Inc., a biopharmaceutical company traded on NASDAQ under the ticker symbol EXEL. The company is conducting clinical trials to evaluate the safety and efficacy of this investigational agent in patients with advanced or metastatic solid tumors.

What phase is XB628 in?

XB628 is in Phase 1 clinical development. The drug is being studied in an early-stage trial that is currently recruiting participants. As an investigational agent, XB628 has not yet received regulatory approval and remains under evaluation for safety and dosing.

What clinical trials is XB628 in?

XB628 is being evaluated in a Phase 1 clinical trial registered as NCT06952010. This study assesses XB628 alone and in combination with zanzalintinib in participants with recurrent advanced or metastatic solid tumors. The trial is actively recruiting in the United States and aims to enroll approximately 303 participants.

Is XB628 the same as zanzalintinib?

No, XB628 is not the same as zanzalintinib. XB628 is a bispecific monoclonal antibody targeting PD-L1 and NKG2A, while zanzalintinib is a separate investigational agent. In the ongoing clinical trial, XB628 is being studied both alone and in combination with zanzalintinib to assess their potential therapeutic effects.