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XmAb808

Phase 1

Head and Neck Squamous Cell Carcinoma | Monoclonal antibody | Oncology |Xencor, Inc.|Last Updated: Aug 7, 2025

Target and mechanism

Molecular targetB7-H3
Target classProtein
ModalityMonoclonal antibody

Success Probability

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Market & Valuation

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Trial Design

UNCONTROLLEDDMC
Total Trials1
Total Enrollment60

FDA Designations

No designations recorded

Clinical trial landscape

XmAb808 · 1 trial · 9 indications

Phase 1 1
NCT05585034Phase 1, First-in-human, Dose-finding and Expansion Study to Evaluate XmAb®808 in Combination With Pembrolizumab in Advanced Solid TumorsHead and Neck Squamous Cell Carcinoma
COMPLETED60 Analytics
PHASE1COMPLETED
Phase 1, First-in-human, Dose-finding and Expansion Study to Evaluate XmAb®808 in Combination With Pembrolizumab in Advanced Solid Tumors
Head and Neck Squamous Cell CarcinomaUnlock trial analytics

Study Endpoints

Primary Endpoints

Incidence of treatment-emergent adverse events (TEAEs)
Up to 5 years

Safety and tolerability as assessed by incidence of TEAEs, including clinically significant changes in safety laboratory tests and clinical findings

Incidence of dose-limiting toxicities (DLTs)
49 days

Safety and tolerability as assessed by incidence of DLTs and all available data which will be used to determine the optimal dose regimen

Secondary Endpoints

Measurement of Cmax
Through study completion, Up to 5 years
Measurement of AUCtau
Through study completion, Up to 5 years
Objective Response Rate
Through study completion, Up to 5 years
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Study Design & Arms

AllocationNA
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Dose Escalation and Expansion XmAb®808 administered in combination with pembrolizumabEXPERIMENTALXmAb®808 in combination with pembrolizumab

Interventions

NameTypeDescription
XmAb®808BIOLOGICALMonoclonal bispecific antibody
Keytruda® (pembrolizumab)BIOLOGICALMonoclonal antibody
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites12

Key Inclusion Criteria: * Part A: Histologically confirmed advanced/metastatic castration-resistant prostate adenocarcinoma, epithelial ovarian cancer, head and neck squamous cell carcinoma, non-small cell lung cancer, urothelial carcinoma, melanoma, renal cell carcinoma, triple-negative breast can...

Countries:United States
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Frequently asked questions about XmAb808

What is XmAb808 used for in Head and Neck Squamous Cell Carcinoma?

XmAb808 is an investigational monoclonal antibody being studied for the treatment of Head and Neck Squamous Cell Carcinoma. It is being evaluated in combination with pembrolizumab in a Phase 1 clinical trial for advanced solid tumors, including this indication. The drug is still in clinical development and is not yet approved.

What does XmAb808 target?

XmAb808 targets B7-H3, a protein that is part of the B7 family of immune checkpoint molecules. By binding to B7-H3, the antibody is designed to modulate immune responses in the tumor microenvironment. This mechanism is being explored in the context of combination therapy for advanced solid tumors.

Who makes XmAb808?

XmAb808 is being developed by Xencor, Inc., a biopharmaceutical company traded on NASDAQ under the ticker XNCR. Xencor is conducting clinical research on this investigational antibody for oncology indications, including Head and Neck Squamous Cell Carcinoma.

What phase is XmAb808 in?

XmAb808 is in Phase 1 clinical development. A first-in-human, dose-finding and expansion study (NCT05585034) has been completed, evaluating the drug in combination with pembrolizumab in advanced solid tumors. The drug remains investigational and has not received FDA approval.

What clinical trials is XmAb808 in?

XmAb808 has been studied in one clinical trial, NCT05585034, a Phase 1, first-in-human, dose-finding and expansion study. This trial evaluated XmAb808 in combination with pembrolizumab in advanced solid tumors, including Head and Neck Squamous Cell Carcinoma, and enrolled 60 participants in the United States.

Is XmAb808 the same as pembrolizumab?

No, XmAb808 is not the same as pembrolizumab. XmAb808 is an investigational monoclonal antibody targeting B7-H3, developed by Xencor. Pembrolizumab is a separate, approved PD-1 inhibitor. In the clinical trial NCT05585034, XmAb808 is being studied in combination with pembrolizumab, not as the same drug.