On October 22, 2025 I-Mab (NASDAQ: IMAB) (I-Mab or the Company), is a global biotechnology platform company committed to accelerating access to innovative medicines for patients worldwide, reported that updated data from the Phase 1 study (NCT04900818) of givastomig as a monotherapy in heavily pre-treated patients (n=45) with gastroesophageal carcinoma (GEC) will be presented as a "short-talk" at the Triple Meeting on October 23, 2025 in Boston, Massachusetts (Presentation #B016). Givastomig is a bispecific antibody targeting CLDN18.2 (Claudin 18.2) and 4-1BB.
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"The Phase 1 givastomig monotherapy data that will be shared at the Triple Meeting continue to demonstrate impressive safety and efficacy, with an 18% ORR in heavily pre-treated gastric cancer patients, with favorable overall safety. These data, showing responses over a dose range from 5 mg/kg Q2W to 18 mg/kg Q3W, further enrich givastomig’s emerging product profile and bolster our confidence that givastomig has the potential to be a best-in-class Claudin18.2-directed therapy across a broad range of CLDN18.2 expression. In Q1 2026, we expect to report topline results from the fully-enrolled Phase 1b dose expansion immune-chemotherapy combination study and initiate a global, randomized Phase 2 combination study. We believe the data from these studies will clearly demonstrate givastomig’s potential to significantly improve the standard of care in the treatment of first line GEC patients with a broad range of Claudin 18.2 expression levels," said Phillip Dennis, MD, PhD, Chief Medical Officer of I-Mab.
"In our experience, givastomig integrates well into the workflow at our center. Based on the monotherapy efficacy across a range of doses and Claudin 18.2 expression levels, and excellent overall safety, givastomig has the potential to be the best-in-class Claudin-directed therapy and combination partner for the treatment of frontline gastric cancer. These follow-up data, plus encouraging initial results from the Phase 1b immune-chemotherapy frontline combination studies, presented earlier this year, give us hope that givastomig treatment can lead to improved treatment outcomes for patients with gastric cancers. We are eager to move forward with the planned Phase 2 study and continue to advance this program," said Samuel J Klempner, MD, Associate Professor of Medicine at Massachusetts General Hospital.
AACR-NCI-EORTC "the Triple Meeting" Conference Information:
Title: Updated Safety, Efficacy and Biomarker Analysis from the Phase I Study of Givastomig, a Novel Claudin 18.2/4-1BB Bispecific Antibody, in Claudin 18.2 Positive Advanced Gastroesophageal Carcinoma (GEC)
Session: Concurrent Session 2: Bispecifics/T-cell Engagers
Speaker: Samuel J. Klempner, MD, Associate Professor of Medicine, Massachusetts General Hospital
Presentation Number: B016
Date and Time: Thursday, October 23, 2025, 6:20 – 6:35 PM ET
Location: Hynes Convention Center
A copy of the Triple Meeting presentation and poster will be available on the Publications and Presentations page of the I-Mab website on October 23, 2025.
Givastomig Phase 1 Monotherapy Updated data Summary GEC (per June 10, 2025 data cut-off):
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Givastomig was well tolerated up to 15 mg/kg Q2W and 18 mg/kg Q3W and continues to show monotherapy activity in heavily pre-treated GEC patients with a wide range of CLDN18.2 expression
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Givastomig may have the ability to target patients with lower CLDN18.2 expression compared with other CLDN18.2 agents
Patients Characteristics:
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45 GEC patients were dosed with givastomig every two weeks (Q2W) across dose levels of: 5mg/kg (n=7), 8 mg/kg (n=5), 12 mg/kg (n=21), 15 mg/kg (n=6) and 18 mg/kg Q3W (n=6) as of the June 10, 2025 data cutoff
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Patients had received a median of 3 prior therapies including 74% with a prior PD-L1 inhibitor
Efficacy Results:
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Confirmed Objective Response Rate (ORR):
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18% of patients (8/45) achieved a partial response (PR)
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5 mg/kg (1/7)
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8 mg/kg (1/5)
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12 mg/kg (4/21)
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15 mg (0/6)
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18 mg/kg Q3W (2/6)
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Claudin 18.2 expression in responders ranged from 11% (1+, 10%; 2+, 1%) to 100% (2+, 10%; 3+, 90%)
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The Disease Control Rate (DCR) was 49%, including stable disease (SD) in 14 patients
Follow-up and Biomarker Data:
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2 patients are ongoing (4%), with 1 PR (8 mg/kg) at 33 months (mo), and 1 PR (18 mg/kg Q3W) at 10 mo
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The median progression free survival (mPFS) and median overall survival (mOS) are 2.96 mo (95% CI 1.71-3.91) and 7.49 mo (95% CI 4.96-12.5), respectively
No statistical difference in ORR, DCR, PFS or OS, between CLDN18.2-high (n=21) and CLDN18.2-low patients (n=24): ORR 19% v. 17% (p=1.00), DCR 57% v. 42% (p=0.46), mPFS 3.68 mo v. 1.84 mo, PFS hazard ratio (HR) 0.87 (p=0.67), and mOS 7.49 mo v. 7.49 mo, OS HR 0.88 (p=0.74), respectively
Safety:
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There were no new safety signals identified with longer follow-up
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No dose limiting toxicities were observed
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Common TREAEs (≥15%, any grade/grade 3) included anemia (27%/9%), white blood cell count decrease (22%/7%), nausea (20%/2%), ALT increase (16%/2%) and AST increase (16%/4%)
About Givastomig
Givastomig (TJ033721 / ABL111) is a bispecific antibody targeting Claudin 18.2 (CLDN18.2)-positive tumor cells. It conditionally activates T cells through the 4-1BB signaling pathway in the tumor microenvironment where CLDN18.2 is expressed. Givastomig is being developed for potential treatment of gastric cancer and other Claudin 18.2-positive gastrointestinal malignancies. In Phase 1 trials, givastomig has shown promising anti-tumor activity attributable to a potential synergistic effect of proximal interaction between CLDN18.2 on tumor cells and 4-1BB on T cells in the tumor microenvironment, while minimizing toxicities commonly seen with other 4-1BB agents.
Givastomig is being jointly developed through a global partnership with ABL Bio, in which I-Mab is the lead party and shares worldwide rights, excluding Greater China and South Korea, equally with ABL Bio.
(Press release, I-Mab Biopharma, OCT 22, 2025, View Source [SID1234656898])