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Zalifrelimab

Phase 1

Advanced Solid Cancers | Small molecule | Oncology |Agenus Inc.|Last Updated: Aug 11, 2026

Target and mechanism

Molecular targetCTLA4
Target classInhibitor
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

UNCONTROLLED
Total Trials1
Total Enrollment89

FDA Designations

No designations recorded

Clinical trial landscape

Zalifrelimab · 2 trials · 3 indications

Phase 1 2
NCT03495882A Study of Zalifrelimab and Balstilimab for Treatment of Participants With Metastatic or Locally Advanced Solid Tumors, and Expansion Into Select Solid Tumors (Cervical)Cervical Cancer
COMPLETED175 Analytics
NCT02694822AGEN1884, an Anti-CTLA-4 Human Monoclonal Antibody in Participants With Advanced or Refractory Cancer and Who Have Progressed With PD-1/PD-L1 Inhibitor as Their Most Recent TherapyAdvanced Solid Cancers
COMPLETED89 Analytics
PHASE1COMPLETED
A Study of Zalifrelimab and Balstilimab for Treatment of Participants With Metastatic or Locally Advanced Solid Tumors, and Expansion Into Select Solid Tumors (Cervical)
Cervical CancerUnlock trial analytics
PHASE1COMPLETED
AGEN1884, an Anti-CTLA-4 Human Monoclonal Antibody in Participants With Advanced or Refractory Cancer and Who Have Progressed With PD-1/PD-L1 Inhibitor as Their Most Recent Therapy
Advanced Solid CancersUnlock trial analytics

Study Endpoints

Primary Endpoints

Phase 2: Objective Response Rate (ORR) - Independent Endpoint Review Committee (IERC)
Up to 2 years

The ORR was defined as the percentage of participants with a confirmed best overall response (BOR) of partial response (PR) or complete response (CR), as determined by an IERC per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1).

Phase 1: Number of Participants Experiencing Dose-limiting Toxicities (DLTs)
First 21 days of treatment

The number of participants with an occurrence of a DLT during dose escalation during the first 21 days of treatment in Phase 1 are reported. Any DLT immediately led to permanent withdrawal of zalifrelimab and balstilimab.

Phase 1: Number of Participants With Dose-limiting Toxicities (DLTs) of Zalifrelimab
Up to 28 days

A DLT was defined as a Grade ≥3 adverse drug reaction (ADR), according to the National Cancer Institute Common Terminology Criteria for Adverse Events version 5, occurring in the DLT evaluation period (28 days after the initial administration of zalifrelimab). An ADR was defined as all noxious and unintended responses to a medicinal product, related to any dose.

Phase 1 and Phase 2: Number of Participants Experiencing Any Treatment-related Adverse Events
Up to 6 years

An adverse event (AE) was defined as any untoward medical occurrence in a clinical investigation participant administered a pharmaceutical product and that did not necessarily have a causal relationship with this treatment. A treatment-related AE was one in which a causal relationship between the medicinal product and the AE was at least a reasonable possibility and could not be ruled out. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.

Phase 1: Maximum Drug Concentration (Cmax) of Zalifrelimab
Day 1 of Cycle 1 (21 days/cycle)

Blood samples were collected at designated timepoints to characterize Cmax of serum zalifrelimab following IV infusion in participants with metastatic or locally advanced solid tumors. Data reported as micrograms/milliliter (ug/mL).

Phase 1: Area Under the Drug Concentration-time Curve From 0 to 21 Days (AUC0-21d) of Zalifrelimab
Day 1 of Cycle 1 (21 days/cycle)

Blood samples were collected at designated timepoints to characterize AUC0-21d of serum zalifrelimab following IV infusion in participants with metastatic or locally advanced solid tumors. Data reported as hour times ug/mL (hour\*ug/mL).

Secondary Endpoints

Phase 1: Maximum Drug Concentration Observed Postdose at Steady-state (Cmax-ss) of Balstilimab and Zalifrelimab
Pre-dose, up to 4 hours post-dose (Day 1 of Cycle 2 and Cycle 3)
Phase 2: Cmax-ss of Balstilimab and Zalifrelimab
Pre-dose, up to 4 hours post-dose (Day 1 of Cycle 4)
Phase 1: Area Under the Drug Concentration-time Curve From Day 0 to Day 14 at Steady-state (AUC0-14d-ss) of Balstilimab and Zalifrelimab
Day 1 through Day 15 (Cycle 2 and Cycle 3)
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Phase 1 - Dose 1: Zalifrelimab + BalstilimabEXPERIMENTALParticipants received zalifrelimab (1 mg/kg every 6 weeks \[Q6W\]) in combination with balstilimab (1 mg/kg every 2 weeks \[Q2W\]).
Phase 1 - Dose 2: Zalifrelimab + BalstilimabEXPERIMENTALParticipants received zalifrelimab (1 mg/kg Q6W) in combination with balstilimab (3 mg/kg Q2W).
Phase 2: Zalifrelimab + BalstilimabEXPERIMENTALParticipants received the RP2D of zalifrelimab (1 mg/kg Q6W) in combination with balstilimab (3 mg/kg Q2W).
ZalifrelimabEXPERIMENTALParticipants received zalifrelimab intravenously.

Interventions

NameTypeDescription
ZalifrelimabDRUGZalifrelimab was administered over 30 minutes and following the infusion of balstilimab.
BalstilimabDRUGBalstilimab infusion was administered over 30 minutes.
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites47

Inclusion Criteria To be eligible for participation in this trial the participant must: 1. Voluntarily agree to participate by giving written informed consent (participation in pharmacogenomics testing is optional). 2. Be ≥18 years of age. 3. Diagnosis: 1. Phase 1: Male or female having a hist...

Countries:United StatesAustraliaBrazilGeorgiaHungaryMoldovaPolandSpainUkraine
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Frequently asked questions about Zalifrelimab

What is Zalifrelimab used for?

Zalifrelimab is an investigational anti-CTLA-4 human monoclonal antibody being studied for the treatment of advanced solid cancers and cervical cancer. It is being developed by Agenus Inc. (AGEN) and is currently in Phase 1 clinical development.

What does Zalifrelimab target?

Zalifrelimab targets CTLA-4, a protein on T cells that acts as an immune checkpoint. By blocking CTLA-4, the antibody aims to enhance the immune system's ability to fight cancer cells. It is being studied in patients with advanced solid tumors and cervical cancer.

Who makes Zalifrelimab?

Zalifrelimab is being developed by Agenus Inc., a biopharmaceutical company traded on the NASDAQ under the ticker symbol AGEN. The drug is currently in Phase 1 clinical trials for advanced solid cancers and cervical cancer.

What phase is Zalifrelimab in?

Zalifrelimab is in Phase 1 clinical development. It is an investigational drug and has not been approved by the FDA. Clinical trials are ongoing to evaluate its safety and efficacy in patients with advanced solid cancers and cervical cancer.

What clinical trials is Zalifrelimab in?

Zalifrelimab has been studied in two completed Phase 1 trials. NCT02694822 evaluated it in patients with advanced solid cancers refractory to PD-1/PD-L1 therapies. NCT03495882 studied it in combination with balstilimab for metastatic or locally advanced solid tumors, including cervical cancer.

Is Zalifrelimab the same as AGEN1884?

Yes, Zalifrelimab is also known as AGEN1884. In clinical trial NCT02694822, the drug was referred to as AGEN1884, an anti-CTLA-4 human monoclonal antibody. Both names refer to the same investigational drug being developed by Agenus Inc.