A Study of ASP2138 Together With Chemotherapy and Pembrolizumab in Adults With Gastric Cancer

Part of paid clinical trials in Saint Louis Park, Minnesota.

Sponsor
Astellas Pharma Global Development, Inc.
Study ID
NCT07673887
Phase
PHASE3
Status
Recruiting
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Conditions

  • Gastric Adenocarcinoma
  • Gastroesophageal Junction (GEJ) Adenocarcinoma

Eligibility Criteria

Sex
ALL
Age
18 Years - N/A
Healthy Volunteers
Not accepted

Interventions

  • ASP2138 — DRUG
    SC Injection
  • Pembrolizumab — DRUG
    IV Infusion
  • Oxaliplatin — DRUG
    IV Infusion
  • Capecitabine — DRUG
    Oral administration
  • Folinic acid — DRUG
    IV Infusion
  • 5-FU — DRUG
    IV Infusion or IV bolus
  • Placebo for ASP2138 — DRUG
    SC Injection
  • Placebo for Pembrolizumab — DRUG
    IV Infusion

Study Details

Claudin 18.2 or CLDN18.2 is a protein found on cells in the digestive system. It is also found in some tumors. Researchers are looking at ways to attack CLDN18.2 to help control tumors. ASP2138 is thought to bind to CLDN18.2 and a type of immune cell called a T cell. This "tells" the immune system to attack the tumor. ASP2138 is a potential treatment for people with gastric cancer (also known as stomach cancer) or gastroesophageal junction cancer (GEJ cancer). GEJ is where the tube that carries food (esophagus) joins the stomach. This study is for people with gastric or GEJ cancer that has spread nearby (locally advanced) and is not removable by surgery (unresectable), or has spread to other parts of the body (metastatic). It is for those whose cancer is human epidermal growth factor receptor 2 (HER2)-negative and CLDN18.2-positive. HER2-negative means the cancer does not have extra HER2 protein, so medicines that target HER2 do not work and are therefore not used. CLDN18.2-positive means people have a certain amount of CLDN18.2 proteins on their cancer cells. In this study, researchers want to learn if ASP2138 given together with standard treatments (chemotherapy and pembrolizumab) help people with HER2-negative and CLDN18.2-positive gastric or GEJ cancer. The main aim is to learn how long people who are given ASP2138 with chemotherapy and pembrolizumab live without their cancer getting worse, compared with placebo given with chemotherapy with or without pembrolizumab, and if they live for longer. Placebo looks like the study treatment but does not have any medicine in it. The main aim of this study is to check how well ASP2138 works when given together with chemotherapy and pembrolizumab compared with placebo plus chemotherapy with or without pembrolizumab. People aged 18 years or older with locally advanced unresectable or metastatic gastric or GEJ cancer can take part. Their tumor should be HER2-negative and CLDN18.2-positive. The study doctors will check people for any health conditions that can exclude them from taking part, interfere with the study procedures, or pose an unacceptable risk. This is a double-blind study. That means the people and the study doctors will not know who will receive which treatment. People will be assigned to one of 2 treatment groups by chance: Group A: People will receive ASP2138 along with chemotherapy and pembrolizumab. Group B: People will receive placebo along with chemotherapy, with or without pembrolizumab. People will keep receiving treatment until their cancer gets worse, they have medical problems that require stopping treatment, or a study rule says they must stop. There will be regular safety checks. People will continue to have scans of their tumor until their cancer becomes worse.

Key Dates

First listed
Jun 29, 2026
Start date
Jun 30, 2026
Status verified
Sep 2026
Primary completion
Feb 28, 2031
Completion
Feb 28, 2031

Study Design

Enrollment
570 participants (estimated)
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT

Arms

  • Experimental: ASP2138 in combination with pembrolizumab and chemotherapy
    Participants will receive ASP2138 as a subcutaneous (SC) injection either once every two weeks (Q2W) or once every three weeks (Q3W) from cycle 1 day 1 (C1D1) followed by intravenous (IV) infusion of pembrolizumab. Participants will be treated with either ASP2138 on days 1 and 22 of each cycle if receiving capecitabine and oxaliplatin (CAPOX) treatment, and on days 1, 15 and 29 of each cycle if receiving modified 5-fluorouracil, folinic acid and oxaliplatin (mFOLFOX6) treatment until discontinuation criteria are met. For all study interventions, the treatment cycle length is 42 days.
  • Placebo Comparator: Placebo for ASP2138 in combination with pembrolizumab and chemotherapy
    Participants will receive placebo matching ASP2138 as a SC injection either Q2W or Q3W from C1D1 followed by IV infusion of pembrolizumab or placebo matching pembrolizumab. Participants will be treated with either placebo matching ASP2138 on days 1 and 22 of each cycle if receiving CAPOX treatment, and on days 1, 15 and 29 of each cycle if receiving mFOLFOX6 treatment until discontinuation criteria are met. For all study interventions, the treatment cycle length is 42 days.

Primary Outcome Measure

Overall Survival (OS) [ Time Frame: Up to 54 months ]

Central Contacts

Locations (1)

FacilityCityStateZIPSite coordinators
Metro Minnesota Community Oncology Research ConsortiumSaint Louis ParkMinnesota55416-

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Metro Minnesota Community Oncology Research Consortium· Saint Louis Park, MN

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