A phase I dose-escalation study of IMAB362 (Zolbetuximab) in patients with advanced gastric and gastro-oesophageal junction cancer.

INTRODUCTION: IMAB362 (Zolbetuximab) is a chimeric monoclonal antibody that binds to Claudin-18.2, a target antigen specific to cancer cells. In vitro, IMAB362 mediates cell death through antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity; thus, IMAB362 may serve as a potent, targeted immunotherapeutic agent. METHODS: This first-in-human phase I study enroled adult patients (N = 15) with advanced gastric or gastro-oesophageal junction cancer into five sequential single dose-escalation cohorts (33, 100, 300, 600, and 1000 mg/m2) following a 3 + 3 design. Safety/tolerability, including determination of maximum tolerated dose and recommended phase II dose, were the primary objectives; secondary objectives included assessment of the IMAB362 pharmacokinetic profile, immunogenicity, and antitumour activity (assessed by Response Evaluation Criteria in Solid Tumors v1.0). RESULTS: IMAB362 was generally well tolerated at all doses, with gastrointestinal toxicities being the most commonly observed treatment-related adverse events. As dose-limiting toxicity was not observed within 4 weeks of treatment, a maximum tolerated dose was not established. The pharmacokinetic profile of IMAB362 appeared to be proportional across the dose range; and mean half-life ranged from 13 to 24 d. While most patients showed progressive disease at weeks 4-5 after a single intravenous IMAB362 infusion, one patient in the 600 mg/m2 dose group achieved and maintained stable disease for approximately 2 months postinfusion. CONCLUSIONS: Findings from this study demonstrate that IMAB362 is generally well tolerated and support further evaluation in patients with gastric/gastro-oesophageal junction cancer. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov, Identifier NCT00909025.

Luciferase mRNA Transfection of Antigen Presenting Cells Permits Sensitive Nonradioactive Measurement of Cellular and Humoral Cytotoxicity.

Immunotherapy is rapidly evolving as an effective treatment option for many cancers. With the emerging fields of cancer vaccines and adoptive cell transfer therapies, there is an increasing demand for high-throughput in vitro cytotoxicity assays that efficiently analyze immune effector functions. The gold standard (51)Cr-release assay is very accurate but has the major disadvantage of being radioactive. We reveal the development of a versatile and nonradioactive firefly luciferase in vitro transcribed (IVT) RNA-based assay. Demonstrating high efficiency, consistency, and excellent target cell viability, our optimized luciferase IVT RNA is used to transfect dividing and nondividing primary antigen presenting cells. Together with the long-lasting expression and minimal background, the direct measurement of intracellular luciferase activity of living cells allows for the monitoring of killing kinetics and displays paramount sensitivity. The ability to cotransfect the IVT RNA of the luciferase reporter and the antigen of interest into the antigen presenting cells and its simple read-out procedure render the assay high-throughput in nature. Results generated were comparable to the (51)Cr release and further confirmed the assay's ability to measure antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity. The assay's combined simplicity, practicality, and efficiency tailor it for the analysis of antigen-specific cellular and humoral effector functions during the development of novel immunotherapies.