I-Mab Highlights Positive Givastomig Phase 1b Dose Escalation Data in Combination with Immunochemotherapy in Patients with 1L Gastric Cancers at ESMO GI 2025

Published

71% objective response rate (ORR) (12/17) per RECIST v1.1, with a favorable safety profile

83% ORR (10/12) in patients across doses selected for ongoing dose expansion study

Responses observed in patients with low PD-L1 and/or CLDN18.2 expression

Updated results to be presented at ESMO GI on July 2nd

Company to host investor event on July 8th

ROCKVILLE, Md., June 26, 2025 (GLOBE NEWSWIRE) -- I-Mab (NASDAQ: IMAB) (the “Company”), a U.S.-based, global biotech company, focused on the development of precision immuno-oncology agents for the treatment of cancer, today announced publication of ESMO Gastrointestinal Cancers Congress 2025 (ESMO GI 2025) abstract #388MO related to positive data from a Phase 1b study evaluating givastomig in combination with nivolumab and mFOLFOX6 chemotherapy for metastatic gastric cancers. An objective response rate (ORR) of 71% (12/17) was observed across all dose levels with an ORR of 83% (10/12) observed at dose levels selected for the ongoing dose expansion study (8 and 12 mg/kg). Responses were rapid and deepened over time, and were observed in tumors with low levels of PD-L1 expression and/or low levels of Claudin 18.2 (CLDN18.2) expression. There was a favorable safety profile, with low incidence of GI and liver toxicities. I-Mab intends to host a virtual investor event on Tuesday, July 8th (register here) to recap the data being presented at ESMO GI.

The abstract is based on the results of the dose escalation part of a Phase 1b study (NCT04900818) evaluating the safety, efficacy, pharmacokinetics (PK), and pharmacodynamics (PD) of givastomig used in combination with nivolumab and mFOLFOX6 as first line therapy (1L) in patients with Claudin 18.2-positive gastric cancers (≥1+ intensity in ≥1% of cells). The primary endpoint is safety. The study only enrolled patients in the U.S.

“We are excited to share positive initial data from the Phase 1b dose escalation study of givastomig in gastric cancers at ESMO GI 2025. Givastomig shows promising activity in the first line setting, with responses that are both rapid onset and durable, deepening over time. This is the first study to evaluate givastomig in combination with immunochemotherapy and we are very pleased by the overall tolerability, consistent pharmacokinetic data and soluble 4-1BB induction. We look forward to sharing the data with the oncology and investment communities at ESMO GI 2025 on July 2nd,” said Phillip Dennis, MD, PhD, Chief Medical Officer of I-Mab.

“Givastomig's strong response data and favorable safety profile are encouraging. I look forward to presenting the data for this novel Claudin 18.2 targeted therapy next week at ESMO GI and discussing with colleagues,” said Samuel J Klempner, MD, Associate Professor of Medicine at Massachusetts General Hospital. “Gastroesophageal cancers continue to be a significant unmet medical need, and novel combination approaches are critical. On behalf of the study team, I am enthusiastic to continue to support the givastomig clinical program.”

ESMO GI Presentation Details:

Title: Preliminary Safety and Efficacy of Givastomig, a Novel Claudin 18.2/4-1BB Bispecific Antibody, in Combination with Nivolumab and mFOLFOX in Metastatic Gastroesophageal Carcinoma (mGEC)Speaker: Samuel J. Klempner, MD, Associate Professor of Medicine, Massachusetts General HospitalPresentation Number: 388MODate and Time: Wednesday, July 2nd at 16:50 CEST (10:50am EST)

Givastomig Phase 1b Dose Escalation Data Summary in 1L Gastric Cancers

  • 17 advanced metastatic gastric cancer patients were treated with givastomig across the 5 mg/kg (n=5), 8 mg/kg (n=6), and 12 mg/kg (n=6) dose levels as of the February 28, 2025, data cutoff. All patients were efficacy evaluable

Patient Characteristics:

  • The 17 patients enrolled in the study were treatment naïve metastatic gastric, esophageal or gastroesophageal adenocarcinomas
  • Patients were HER2-negative, Claudin 18.2-positive (defined as >1+ intensity in >1% of tumor cells) regardless of PD-L1 expression levels
  • All patients were enrolled at sites within the United States

Efficacy Results:

  • Objective Response Rates (ORRs):
    • 71% of patients (12/17) achieved a partial response (PR) per RECIST v1.1
      • 5 mg/kg (2/5)
      • 8 mg/kg (5/6)
      • 12 mg/kg (5/6), with one unconfirmed response as of the data cutoff
    • At the doses selected for dose expansion (8 and 12 mg/kg), 83% (10/12) of patients achieved PRs
    • 80% of patients (4/5) with CLDN18.2 expression below 75% (CLDN-Low) achieved a PR. The CLDN-Low response rate increased to 100% of patients (3/3) in the doses selected for expansion (8 and 12 mg/kg)
  • The disease control rate (DCR) was 100% across the three dose levels
  • Dose-dependent PK was observed, similar to monotherapy PK.
  • Patients also experienced a dose dependent induction of soluble 4-1BB, a positive indicator of T cell activation and engagement
ORR: % (n)All(n=17)Cohorts Chosen for expansion(8 and 12 mg/kg)(n=12)
PD-L1  
Any71 (12/17)83 (10/12)
≥582 (9/11)89 (8/9)

The views and opinions expressed herein are the views and opinions of the author and do not necessarily reflect those of Nasdaq, Inc.

In This Story

NBP