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AB598

Phase 1

Advanced Cancer | Small molecule | Oncology |Arcus Biosciences, Inc.|Trials Updated: Sep 29, 2026

AB598 development status

Highest phase Phase 1
Registered trials 1 across 1 sponsor since Jun 2023

AB598 target and mechanism

Molecular targetCD39
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

CONTROLLEDBiomarker
Total Trials1
Total Enrollment40

FDA Designations

No designations recorded

AB598 clinical trials

AB598 · 1 trial · 12 indications

Phase 1 1
NCT05891171Study of AB598 Monotherapy and Combination Therapy in Participants With Advanced CancersAdvanced Cancer
ACTIVE NOT_RECRUITING40 Analytics
PHASE1ACTIVE NOT_RECRUITING
Study of AB598 Monotherapy and Combination Therapy in Participants With Advanced Cancers
Advanced CancerUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)
Up to 2 years
Dose Escalation Cohorts: Number of Participants with Dose-Limiting Toxicities (DLTs)
Up to 2 years

Secondary Endpoints

Area Under the Concentration-Time Curve from Administration ("0") to the Time That the Drug is No Longer Present in the Body ("infinity") (AUC 0-inf) in Whole Blood and Plasma
Predose, Up to 4 hours post dose
Maximum Concentration (Cmax) in Whole Blood and Plasma
Predose, Up to 4 hours post dose
Time to Maximum Concentration (Tmax) in Whole Blood and Plasma
Predose, Up to 4 hours post dose
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Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSEQUENTIAL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Dose Escalation Cohort 1EXPERIMENTALParticipants will receive AB598 intravenous (IV) infusion once every 3 weeks
Dose Escalation Cohort 2EXPERIMENTALParticipants will receive AB598 IV infusion once every 3 weeks
Dose Escalation Cohort 3EXPERIMENTALParticipants will receive AB598 IV infusion once every 3 weeks
Dose Escalation Cohort 4EXPERIMENTALParticipants will receive AB598 IV infusion once every 3 weeks
Pharmacodynamic Cohort 1EXPERIMENTALParticipants will receive AB598 IV infusion once every 3 weeks
Pharmacodynamic Cohort 2EXPERIMENTALParticipants will receive AB598 IV infusion once every 3 weeks
Pharmacodynamic Cohort 3EXPERIMENTALParticipants will receive AB598 IV infusion once every 3 weeks
Dose Expansion Gastric/GEJ Cancer (phase 1b)EXPERIMENTALParticipants will receive AB598 IV infusion every 2 weeks in combination with zimberelimab and FOLFOX (oxaliplatin, leucovorin, fluorouracil)

Interventions

NameTypeDescription
AB598DRUGAdministered as specified in the treatment arm
ZimberelimabDRUGAdministered as specified in the treatment arm
FluorouracilDRUGAdministered as specified in the treatment arm
LeucovorinDRUGAdministered as specified in the treatment arm
OxaliplatinDRUGAdministered as specified in the treatment arm
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Eligibility Criteria

Age Range18 Years to N/A
SexALL
Healthy VolunteersNo
Study Sites14

Key Inclusion Criteria: * Must have at least 1 measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) guidance * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 * Prior systemic radiation or whole brain radiation therapy must have been completed at ...

Countries:United StatesAustraliaTaiwan
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Competitive Landscape -Cancer 7 trials (matched to "Advanced Cancer")

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Recent Changes (Last 90 Days)

LOWSep 29, 2026NCT05891171lastUpdatePostDate: changed
LOWSep 29, 2026NCT05891171lastUpdatePostDate: changed
LOWAug 31, 2026NCT05891171lastUpdatePostDate: changed
LOWAug 31, 2026NCT05891171lastUpdatePostDate: changed
LOWJul 30, 2026NCT05891171lastUpdatePostDate: changed
LOWJul 30, 2026NCT05891171lastUpdatePostDate: changed

Frequently asked questions about AB598

What is AB598?

AB598 is an investigational small molecule being developed by Arcus Biosciences for the treatment of advanced cancer. It is a CD39-targeted agent and is currently in Phase 1 clinical development. It is not yet approved for any indication and remains under study in a single active trial.

What is AB598 used for in advanced cancer?

AB598 is being studied for advanced malignancies, including bladder cancer, cervical cancer, esophageal cancer, gastric and gastroesophageal-junction cancer, head and neck squamous cell carcinoma, non-small cell lung cancer, ovarian cancer, renal cell carcinoma, and triple negative breast cancer. It is investigational and has not been approved for any of these uses.

What does AB598 target?

AB598 targets CD39, an enzyme involved in the adenosine pathway within the tumor microenvironment. By acting on CD39, the small molecule is designed to modulate this pathway in cancer. The Phase 1 study evaluates AB598 both as monotherapy and in combination therapy in participants with advanced cancers.

Who is developing AB598?

AB598 is being developed by Arcus Biosciences, Inc., a biopharmaceutical company that trades under the ticker RCUS. Arcus is running the clinical program for the asset, which is currently in Phase 1 development for advanced cancer.

What phase is AB598 in?

AB598 is in Phase 1 clinical development. It is an investigational agent and has not been approved by the FDA or any other regulatory authority. The ongoing study is a first-in-human style Phase 1 trial evaluating the drug in participants with advanced cancers.

What clinical trials is AB598 in?

AB598 is being evaluated in the Phase 1 trial NCT05891171, titled Study of AB598 Monotherapy and Combination Therapy in Participants With Advanced Cancers. The trial has an enrollment of 40 participants, is active but not recruiting, and is conducted in the United States, Australia, and Taiwan.