A New Treatment Approach for One of the Most Challenging Forms of Gastric Cancer
Gastric cancer remains one of the most common cancers worldwide, with a particularly high disease burden in China. Approximately 42% of patients are diagnosed at an advanced stage, and patients with stage IV disease continue to face poor long-term outcomes.
Among advanced gastric cancers, peritoneal metastasis represents one of the most difficult disease patterns to treat. Patients with gastric cancer spread to the peritoneum often have limited treatment options, poor response to conventional therapies, and unfavorable survival outcomes.
The emergence of precision medicine has created new opportunities for these patients. One promising target is Claudin18.2 (CLDN18.2), a protein highly and consistently expressed in gastric cancer cells. Studies have shown that CLDN18.2 expression remains relatively stable between primary tumors and metastatic lesions, including peritoneal metastases, making it an attractive target for targeted therapies.
Satricabtagene autoleucel (CT041), a CLDN18.2-directed autologous CAR-T cell therapy, was developed based on this biological characteristic. As the world’s first approved CAR-T therapy for solid tumors, CT041 represents a major milestone in cancer immunotherapy and offers a new treatment option for patients with advanced gastric cancer.
A recently published case report in the international journal Journal of Hematology & Oncology demonstrated the potential of CT041 in a patient with gastric cancer and peritoneal metastasis, showing long-term disease control, successful conversion surgery, and durable survival.
Patient Achieved PCI Score Reduction From 9 to 0 After CAR-T Therapy
The patient was a 53-year-old woman diagnosed with gastric cancer accompanied by peritoneal metastasis.
She initially received six cycles of first-line chemotherapy consisting of:
- Paclitaxel
- Oxaliplatin
- Oral S-1 (tegafur/gimeracil/oteracil)
Imaging evaluation showed stable disease (SD).
A diagnostic laparoscopy performed on June 1, 2021 revealed multiple pelvic peritoneal implants. The patient’s Peritoneal Cancer Index (PCI) score was 9, and biopsy confirmed metastatic signet ring cell carcinoma.
The patient received:
- Intraperitoneal docetaxel hyperthermic intraperitoneal chemotherapy (HIPEC)
- Additional intraperitoneal paclitaxel combined with oral S-1 therapy
Further immunohistochemical testing showed:
- CLDN18.2 expression: IHC 3+
- Positive tumor cells: 90%
Based on the high CLDN18.2 expression, the patient was enrolled in the CT041-CG4006 clinical trial, receiving CT041 as maintenance therapy following first-line induction treatment.
Rapid Tumor Response After CLDN18.2 CAR-T Treatment
For CAR-T cell manufacturing, the patient underwent leukapheresis on November 16, 2021.
Before CT041 infusion, she received lymphodepletion therapy consisting of:
- Fludarabine
- Cyclophosphamide
- Albumin-bound paclitaxel
The patient received the first CT041 infusion on:
December 20, 2021
Dose:
250 × 10⁶ CAR-T cells
Remarkably, only four weeks after infusion, imaging showed:
- Partial response (PR)
- Reduction of peritoneal metastatic lesions
Seven months after infusion, the patient continued to maintain PR.
Following multidisciplinary evaluation, her clinical stage improved to:
ycT3N0M0
CAR-T Therapy Enabled Conversion Surgery
Eight months after CT041 infusion, on September 1, 2022, laparoscopic exploration showed:
- No visible peritoneal metastases
- No metastatic lesions in the omentum or mesentery
- PCI score reduced from 9 to 0
The patient subsequently underwent:
- Total gastrectomy
- D2 lymph node dissection
Postoperative pathology showed:
ypT2N0
This represented a major treatment transformation—from initially unresectable gastric cancer with peritoneal metastasis to successful surgical removal after CAR-T therapy.
Long-Term Disease Control for 48 Months
During follow-up, CT imaging in January 2023 showed enlarged bilateral ovaries.
A second laparoscopic exploration confirmed:
- Bilateral ovarian metastatic Krukenberg tumors
- No recurrence in other peritoneal areas
The patient underwent:
- Bilateral salpingo-oophorectomy
A second CT041 infusion was administered on:
May 29, 2023
As of January 6, 2026:
- No further disease progression was observed
- Peritoneal metastasis remained controlled for 48 months after initial CT041 infusion
CAR-T Cells Persisted Within Tumor Tissue
Although CAR-T cells in peripheral blood reached peak levels around day 10 after infusion and became nearly undetectable after day 30, researchers detected CAR-T cells in:
- Gastric tumor tissue removed 8 months after infusion
- Ovarian metastatic tissue removed 13 months after infusion
These findings suggest that CT041 CAR-T cells can migrate into tumor tissues and persist locally, potentially providing continued immune surveillance against cancer cells.
Favorable Safety Profile
Throughout treatment:
- No immune effector cell-associated neurotoxicity syndrome (ICANS) occurred
- No grade ≥3 cytokine release syndrome (CRS) occurred
The safety profile was considered manageable.
Clinical Significance: A Potential New Option for Gastric Cancer Peritoneal Metastasis
Professor Qi Changsong from Peking University Cancer Hospital commented that this case demonstrates a significant clinical breakthrough.
Peritoneal metastasis remains one of the most challenging complications of gastric cancer. Current systemic therapies, including immunotherapy and targeted therapies, still provide limited benefit for many patients.
This case highlights several important findings:
1. Conversion From Unresectable Disease to Surgical Treatment
After CT041 therapy:
- PCI score decreased from 9 to 0
- Peritoneal metastases disappeared
- Patient successfully underwent radical surgery
2. Durable Disease Control
The patient achieved:
- 48 months of peritoneal metastasis control
- Long-term survival after CAR-T therapy
3. Evidence of CAR-T Persistence
Detection of CAR-T cells in tumor tissues suggests local persistence and ongoing anti-tumor activity.
Clinical Evidence From CT041-CG4006 and CT041-ST-01 Studies
This case came from the CT041-CG4006 clinical study, a multicenter phase I trial led by Professor Shen Lin evaluating CT041 in CLDN18.2-positive advanced gastrointestinal cancers.
In the first-line sequential maintenance cohort:
- Patients received induction therapy followed by CT041
- The latest results presented at ASCO 2026 showed more than 4.5 years of follow-up
Despite a highly difficult patient population:
- 60% Lauren diffuse type gastric cancer
- 80% signet ring cell carcinoma
- 80% peritoneal metastasis
Results showed:
- Objective response rate (ORR): 100% among patients with measurable lesions
- Median first-line PFS: 20.9 months
The long-term control observed in this patient further supports the potential of CT041 for gastric cancer patients with peritoneal metastasis.
Additionally, the confirmatory CT041-ST-01 study demonstrated meaningful improvements in response rates, progression-free survival, and overall survival among patients with previously treated advanced gastric or gastroesophageal junction adenocarcinoma.
From Breakthrough Therapy to Broader Clinical Applications
Satricabtagene autoleucel (CT041) has now been approved in China for:
- CLDN18.2-positive
- HER2-negative
- Advanced gastric or gastroesophageal junction adenocarcinoma
- Patients who failed at least two prior systemic treatments
It became the world’s first approved CAR-T therapy for solid tumors, marking a historic milestone in cancer immunotherapy.
The therapy has also been incorporated into the updated notes of the CSCO Gastric Cancer Diagnosis and Treatment Guidelines (2026 edition).
Future research is exploring earlier treatment settings, including:
- First-line maintenance therapy
- Neoadjuvant treatment
- Perioperative therapy
Beyond gastric cancer, CLDN18.2 expression in other cancers such as pancreatic and biliary tract cancers may provide opportunities for future expansion.
For patients with gastric cancer and peritoneal metastasis, CT041 represents a promising new direction and a potential pathway toward longer survival and improved treatment outcomes.
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