Clinicopathological significance and immunotherapeutic outcome of claudin 18.2 expression in advanced gastric cancer: A retrospective study.

Objective: Immunotherapeutic outcomes and clinical characteristics of claudin 18 isoform 2 positive (CLDN18.2-positive) gastric cancer (GC) vary in different clinical studies, making it difficult to optimize anti-CLDN18.2 therapy. We conducted a retrospective analysis to explore the association of CLDN18.2 expression with clinicopathological characteristics and immunotherapeutic outcomes in GC. Methods: A total of 536 advanced GC patients from 2019 to 2021 in the CT041-CG4006 and CT041-ST-01 clinical trials were included in the analysis. CLDN18.2 expression on ≥40% of tumor cells (2+, 40%) and CLDN18.2 expression on ≥70% of tumor cells (2+, 70%) were considered the two levels of positively expressed GC. The clinicopathological characteristics and immunotherapy outcomes of GC patients were analyzed according to CLDN18.2 expression status. Results: CLDN18.2 was expressed in 57.6% (cut-off: 2+, 40%) and 48.9% (cut-off: 2+, 70%) of patients. Programmed death-ligand 1 (PD-L1) and CLDN18.2 were co-expressed in 19.8% [combined positive score (CPS)≥1, CLDN18.2 (cut-off: 2+, 40%)] and 17.2% [CPS≥5, CLDN18.2 (cut-off: 2+, 70%)] of patients. CLDN18.2 expression positively correlated with younger age, female sex, non-gastroesophageal junction (non-GEJ), and diffuse phenotype (P<0.001). HER2 and PD-L1 expression were significantly lower in CLDN18.2-positive GC (both P<0.05). Uterine adnexa metastasis (P<0.001) was more frequent and liver metastasis (P<0.001) was less common in CLDN18.2-positive GC. Overall survival and immunotherapy-related progression-free survival (irPFS) were inferior in the CLDN18.2-positive group. Conclusions: CLDN18.2-positive GC is associated with poor prognosis and worse immunotherapeutic outcomes. The combination of anti-CLDN18.2 therapy, anti-PD-L1/PD-1 therapy, and chemotherapy for GC requires further investigation.

Claudin 18.2 as a novel therapeutic target.

Claudin 18.2, a tight-junction molecule predominantly found in the nonmalignant gastric epithelium, becomes accessible on the tumour cell surface during malignant transformation, thereby providing an appealing target for cancer therapy. Data from two phase III trials testing the anti-claudin 18.2 antibody zolbetuximab have established claudin 18.2-positive advanced-stage gastric cancers as an independent therapeutic subset that derives benefit from the addition of this agent to chemotherapy. This development has substantially increased the percentage of patients eligible for targeted therapy. Furthermore, newer treatments, such as high-affinity monoclonal antibodies, bispecific antibodies, chimeric antigen receptor T cells and antibody-drug conjugates capable of bystander killing effects, have shown considerable promise in patients with claudin 18.2-expressing gastric cancers. This new development has resulted from drug developers moving beyond traditional targets, such as driver gene alterations or growth factors. In this Review, we highlight the biological rationale and explore the clinical activity of therapies that target claudin 18.2 in patients with advanced-stage gastric cancer and explore the potential for expansion of claudin 18.2-targeted therapies to patients with other claudin 18.2-positive solid tumours.

68Ga-NC-BCH Whole-Body PET Imaging Rapidly Targets Claudin18.2 in Lesions in Gastrointestinal Cancer Patients.

68Ga-labeled nanobody (68Ga-NC-BCH) is a single-domain antibody-based PET imaging agent. We conducted a first-in-humans study of 68Ga-NC-BCH for PET to determine its in vivo biodistribution, metabolism, radiation dosimetry, safety, and potential for quantifying claudin-18 isoform 2 (CLDN18.2) expression in gastrointestinal cancer patients. Methods: Initially, we synthesized the probe 68Ga-NC-BCH and performed preclinical evaluations on human gastric adenocarcinoma cell lines and xenograft mouse models. Next, we performed a translational study with a pilot cohort of patients with advanced gastrointestinal cancer on a total-body PET/CT scanner. Radiopharmaceutical biodistribution, radiation dosimetry, and the relationship between tumor uptake and CLDN18.2 expression were evaluated. Results: 68Ga-NC-BCH was stably prepared and demonstrated good radiochemical properties. According to preclinical evaluation,68Ga-NC-BCH exhibited rapid blood clearance, high affinity for CLDN18.2, and high specific uptake in CLDN18.2-positive cells and xenograft mouse models. 68Ga-NC-BCH displayed high uptake in the stomach and kidney and slight uptake in the pancreas. Compared with 18F-FDG, 68Ga-NC-BCH showed significant differences in uptake in lesions with different levels of CLDN18.2 expression. Conclusion: A clear correlation was detected between PET SUV and CLDN18.2 expression, suggesting that 68Ga-NC-BCH PET could be used as a companion diagnostic tool for optimizing treatments that target CLDN18.2 in tumors.

Disitamab vedotin (RC48) plus toripalimab for HER2-expressing advanced gastric or gastroesophageal junction and other solid tumours: a multicentre, open label, dose escalation and expansion phase 1 trial.

Background: Although the antibody-drug conjugates (ADCs) have significantly improved the survival outcomes of patients with human epidermal receptor 2 (HER2)-expressing gastric or gastroesophageal junction (G/GEJ) cancer, the efficacy of ADC used as a single agent is limited. Therefore, it is necessary to investigate effective and safe combination regimens. Preclinical data indicated a synergetic antitumour effect of RC48 and programmed cell death protein 1 (PD-1) inhibitors. We aimed to evaluate the safety and efficacy of RC48 plus toripalimab in patients with HER2-expressing G/GEJ cancer and other solid tumours. Methods: This was a open-label, multicentre, phase 1 trial performed at three hospitals in China. Eligible patients had advanced G/GEJ cancer or other solid tumours with HER2 IHC≥1 or ISH positivity and were refractory to at least one line of treatment, or standard treatment was intolerable or unavailable for these patients. This study followed a "3 + 3" design with predefined RC48 dosages of 2.0 mg/kg and 2.5 mg/kg plus toripalimab 3 mg/kg, once every 2 weeks (q2w). The primary objectives were to evaluate the safety and determine the recommended phase II dose (RP2D), and the secondary objectives included assessing the pharmacokinetics (PK) and preliminary efficacy. This study was registered with ClinicalTrials.gov, NCT04280341. Findings: Between July 13, 2020 and August 30, 2022, 56 patients, including 30 patients with G/GEJ cancer and 26 patients with other solid tumours, were enrolled and received RC48 plus toripalimab (n = 7 for RC48 2.0 mg/kg, toripalimab 3 mg/kg, q2w; n = 49 for RC48 2.5 mg/kg, toripalimab 3 mg/kg, q2w). No dose-limiting toxic effects occurred. The RP2D was declared as RC48 2.5 mg/kg plus toripalimab 3 mg/kg, q2w. The most common grade 3 adverse events were a decreased neutrophil count (n = 13), and a decreased white blood cell count (n = 7). The efficacy assessment was completed for 52 patients. Among patients with G/GEJ cancer (n = 30), the confirmed objective response rate (ORR) was 43% (12/28, 95% CI 25, 63), median progression-free survival (PFS) was 6.2 months (95% CI 4.0, 6.9), median overall survival (OS) was 16.8 months (95% CI 7.2, NE). The ORR of patients with G/GEJ cancer receiving RP2D (n = 24) reached 50% (11/22, 95% CI 28, 72), with median PFS of 5.1 months (95% CI 1.4, 7.3) and median OS of 14.0 months (95% CI 6.3, NE). Among patients with G/GEJ cancer who received RP2D, a clinical benefit was observed in both HER2-positive and low HER2 expressing populations, with an ORR of 56% (5/9, 95% CI 21, 86) vs. 46% (6/13, 95% CI 19, 75), median PFS of 7.8 months (95% CI 0.9, NE) vs. 5.1 months (95% CI 1.2, 6.9), median OS of NE months (95% CI 4.3, NE) vs. 14.0 months (95% CI 5.1, NE), respectively. Antitumour activity was also observed for other solid tumours, including breast cancer (5/13) and endometrial carcinoma (1/1). Interpretation: Our findings suggested that RC48 plus toripalimab had a manageable safety profile and showed encouraging efficacy in pretreated patients with HER2-positive and low HER2-expressing G/GEJ cancer. The findings of our phase 1 clinical trial support further investigation of HER2-targeted ADC plus immunotherapy in HER2-expressing G/GEJ cancer and pancancer treatment in the future. Funding: Beijing Municipal Medical Research Institutes, Beijing Medical Research Institute (Z200015).

Safety and Efficacy of CT041 in Patients With Refractory Metastatic Pancreatic Cancer: A Pooled Analysis of Two Early-Phase Trials.

PURPOSE: CT041 is a chimeric antigen receptor (CAR)-modified T-cell therapy that specifically targets claudin18.2 in solid tumors. Here, we report the pooled analysis results of two exploratory clinical trials to evaluate CT041 in patients with previously treated pancreatic cancer (PC). PATIENTS AND METHODS: These two multicenter, open-label phase I/Ib trials (CT041-CG4006, CT041-ST-01) have a similar target population and evaluation schedule. The primary objective was to assess the safety and tolerability of CT041, whereas secondary objectives included efficacy, pharmacokinetics, and immunogenicity. RESULTS: The combined cohort comprised 24 patients with advanced PC. Among them, five patients (20.8%) had previously received one line of therapy, whereas 19 (79.2%) received ≥2 lines of therapy. The most common treatment-emergent adverse events of grade 3 or more were preconditioning-related hematologic toxicities. Cytokine release syndrome (CRS) and GI disorders were most reported grade 1 or 2 adverse events. The overall response rate and disease control rate were 16.7% and 70.8%. The median progression-free survival (mPFS) after infusion was 3.3 months (95% CI, 1.8 to 6.2), and the median overall survival (mOS) was 10.0 months (95% CI, 5.5 to 17.6). The median duration of response (mDoR)was 9.5 months (95% CI, 2.6 to Not reached), with a DoR rate at 12 months of 50% (95% CI, 5.8 to 84.5). The mPFS (6.0 v 1.0 months, P < .001) and mOS (17.6 v 4.0 months, P < .001) were prolonged in patients achieving partial response/stable disease than the progressive disease group. CA19-9 levels had reduced by at least 30% in 17 (70.8%) patients. CONCLUSION: In patients with metastatic PC after progression on previous therapy, CT041 demonstrated a tolerable safety profile and encouraging anticancer efficacy signals. Response benefit observed here needs to be ascertained in the future.

Claudin18.2-specific CAR T cells in gastrointestinal cancers: phase 1 trial final results.

Claudin18.2 (CLDN18.2) is highly expressed with the development of various malignant tumors, especially gastrointestinal cancers, and is emerging as a new target for cancer treatment. Satricabtagene autoleucel (satri-cel)/CT041 is an autologous chimeric antigen receptor (CAR) T cell targeting CLDN18.2, and the interim results of the CT041-CG4006 trial were reported in June 2022. Here we present the final results of this single-arm, open-label, phase 1 trial, which evaluated the safety and efficacy of satri-cel in patients with CLDN18.2-positive advanced gastrointestinal cancers. This trial included a dose-escalation stage (n = 15) and a dose-expansion stage in four different cohorts (total n = 83): cohort 1, satri-cel monotherapy in 61 patients with standard chemotherapy-refractory gastrointestinal cancers; cohort 2, satri-cel plus anti-PD-1 therapy in 15 patients with standard chemotherapy-refractory gastrointestinal cancers; cohort 3, satri-cel as sequential treatment after first-line therapy in five patients with gastrointestinal cancers; and cohort 4, satri-cel monotherapy in two patients with anti-CLDN18.2 monoclonal antibody-refractory gastric cancer. The primary endpoint was safety; secondary endpoints included efficacy, pharmacokinetics and immunogenicity. A total of 98 patients received satri-cel infusion, among whom 89 were dosed with 2.5 × 108, six with 3.75 × 108 and three with 5.0 × 108 CAR T cells. Median follow-up was 32.4 months (95% confidence interval (CI): 27.3, 36.5) since apheresis. No dose-limiting toxicities, treatment-related deaths or immune effector cell-associated neurotoxicity syndrome were reported. Cytokine release syndrome occurred in 96.9% of patients, all classified as grade 1-2. Gastric mucosal injuries were identified in eight (8.2%) patients. The overall response rate and disease control rate in all 98 patients were 38.8% and 91.8%, respectively, and the median progression-free survival and overall survival were 4.4 months (95% CI: 3.7, 6.6) and 8.8 months (95% CI: 7.1, 10.2), respectively. Satri-cel demonstrates therapeutic potential with a manageable safety profile in patients with CLDN18.2-positive advanced gastrointestinal cancer. ClinicalTrials.gov identifier: NCT03874897 .