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Active, not recruitingNCT05891171ARC-25Updated Sep 29, 2026

Study of AB598 Monotherapy and Combination Therapy in Participants With Advanced Cancers

A Phase 1 interventional study of AB598 and Zimberelimab in Advanced Cancer, Advanced Malignancies and Bladder Cancer, sponsored by Arcus Biosciences, Inc.. Active, not recruiting at 14 sites in 3 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-29.

Sponsored by Arcus Biosciences, Inc. · Phase 1, Interventional, and Treatment

Phase
Phase 1
Study type
Interventional
Enrollment
40
Allocation
Non-randomized
Ages
18 Years and older
Sex
All
01

Study summary

The primary purpose of this study is to assess the safety and tolerability of AB598 in participants with advanced malignancies.

02

Conditions studied

  • Advanced Cancer
  • Advanced Malignancies
  • Bladder Cancer
  • Cervical Cancer
  • Esophageal Cancer
  • Gastric Cancer
  • Gastroesophageal-junction Cancer (GEJ)
  • Head and Neck Squamous Cell Carcinoma (HNSCC)
  • Non-Small Cell Lung Cancer (NSCLC)
  • Ovarian Cancer
  • Renal Cell Carcinoma (RCC)
  • Triple Negative Breast Cancer (TNBC)

Keywords

  • AB598
  • AB122
  • Zimberelimab
03

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Eligibility criteria

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 least 4 weeks before investigational product (IP) administration. Other palliative radiotherapy must be completed 2 weeks before investigational product administration, if radiation therapy-related AEs have resolved to Grade ≤ 1.
  • Monotherapy-specific criteria for dose escalation and PD cohorts:

    • Dose Escalation: Participants may have any pathologically confirmed advanced or metastatic solid tumor for which standard therapy has proven ineffective, intolerable, or is considered inappropriate.
    • Pharmacodynamic Cohorts: Participants may have any pathologically confirmed advanced or metastatic solid tumors for which standard therapy has proven ineffective, intolerable, or is considered inappropriate. Participants must be able to undergo collection of a fresh frozen biopsy during screening, as well as provide an on-treatment fresh frozen biopsy.
  • Dose Expansion cohort criteria:

    • Histologically confirmed, documented diagnosis of HER2-negative locally advanced unresectable or metastatic gastric or GEJ adenocarcinoma.
    • No prior systemic treatment for locally advanced unresectable or metastatic disease.
    • Cannot have progressed within 6 months of prior platinum-based chemotherapy for earlier stage disease.

Key Exclusion Criteria:

  • Use of any live vaccines against infectious diseases (eg, influenza, varicella) within 4 weeks (28 days) of initiation of study
  • Underlying medical conditions or AEs that, in the investigator or sponsor's opinion, will make the administration of the study drugs hazardous
  • Any active or documented history of autoimmune disease including but not limited to inflammatory bowel disease, celiac disease, Wegner syndrome, Hashimoto syndrome, systemic lupus erythematosus, scleroderma, sarcoidosis, or autoimmune hepatitis, within 3 years of the first dose of study treatment
  • History of trauma or major surgery within 28 days prior to the first dose of study drug
  • Treatment with systemic immunosuppressive medication within 2 weeks prior to initiation of study treatment, or anticipation of need for systemic immunosuppressant medication during study treatment with certain protocol specified exceptions

Note: Other protocol defined Inclusion/Exclusion criteria may apply.

04

Study design

Phase
Phase 1
Primary purpose
Treatment
Allocation
Non-randomized
Intervention model
Sequential assignment
Masking
None (open label)
Enrollment
40 participants (actual)

Study arms

  • Experimental
    Dose Escalation Cohort 1

    Participants will receive AB598 intravenous (IV) infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Dose Escalation Cohort 2

    Participants will receive AB598 IV infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Dose Escalation Cohort 3

    Participants will receive AB598 IV infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Dose Escalation Cohort 4

    Participants will receive AB598 IV infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Pharmacodynamic Cohort 1

    Participants will receive AB598 IV infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Pharmacodynamic Cohort 2

    Participants will receive AB598 IV infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Pharmacodynamic Cohort 3

    Participants will receive AB598 IV infusion once every 3 weeks

    Drug: AB598

  • Experimental
    Dose Expansion Gastric/GEJ Cancer (phase 1b)

    Participants will receive AB598 IV infusion every 2 weeks in combination with zimberelimab and FOLFOX (oxaliplatin, leucovorin, fluorouracil)

    Drug: AB598 · Drug: Zimberelimab · Drug: Fluorouracil · Drug: Leucovorin · Drug: Oxaliplatin

Interventions

  • DrugAB598

    Administered as specified in the treatment arm

  • DrugZimberelimab

    Administered as specified in the treatment arm

    Also known as: AB122

  • DrugFluorouracil

    Administered as specified in the treatment arm

  • DrugLeucovorin

    Administered as specified in the treatment arm

  • DrugOxaliplatin

    Administered as specified in the treatment arm

05

What researchers measure

Primary outcomes

  1. Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)

    Time frame: Up to 2 years

  2. Dose Escalation Cohorts: Number of Participants with Dose-Limiting Toxicities (DLTs)

    Time frame: Up to 2 years

Secondary outcomes

  1. 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

    Time frame: Predose, Up to 4 hours post dose

  2. Maximum Concentration (Cmax) in Whole Blood and Plasma

    Time frame: Predose, Up to 4 hours post dose

  3. Time to Maximum Concentration (Tmax) in Whole Blood and Plasma

    Time frame: Predose, Up to 4 hours post dose

  4. Number of Participants Who Test Positive for Antidrug Antibodies (ADAs) to AB598

    Time frame: Up to 2 years

  5. Objective Response Rate (ORR)

    Time frame: Up to 2 years

  6. Dose Expansion Cohort: Duration of Response (DOR)

    Time frame: Up to 2 years

06

Study locations

14 sites
  • Research Site
    Phoenix, Arizona 85054, United States
  • Research Site
    Jacksonville, Florida 32224, United States
  • Research Site
    Lake City, Florida 32024, United States
  • Research Site
    Hinsdale, Illinois 60521, United States
  • Research Site
    Detroit, Michigan 48201, United States
  • Research Site
    Rochester, Minnesota 55905, United States
  • Research Site
    New Brunswick, New Jersey 08901, United States
  • Research Site
    Canton, Ohio 44718, United States
  • Research Site
    Cleveland, Ohio 44106, United States
  • Research Site
    Irving, Texas 75039, United States
  • Research Site
    Fairfax, Virginia 22031, United States
  • Research Site
    Adelaide, Australia
  • Research Site
    Tainan, Taiwan
  • Research Site
    Taipei, Taiwan
07

References and documents

Individual participant data

Plan to share: Yes — Arcus will provide access to individual de-identified participant data and related study documents (e.g., protocol, Statistical Analysis Plan \[SAP\], Clinical Study Report \[CSR\]) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. For more information, please visit our website.

Supporting information: Study protocol, Sap, Csr

08

Registry details

Key details

Study ID
NCT05891171
Lead sponsor
Arcus Biosciences, Inc.
Responsible party
Sponsor
First posted
Jun 6, 2023
Start date
Oct 13, 2023
Primary completion
Sep 2027 (estimated)
Completion
Sep 2027 (estimated)
Last update
Sep 29, 2026

Study contacts

Medical Director
study director · Arcus Biosciences

Oversight

FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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