A phase Ib study of photoimmunotherapy with ASP-1929 in combination with nivolumab for advanced gastric cancer (GE-PIT, EPOC1901).

Background: Photoimmunotherapy with ASP-1929 (cetuximab conjugated to IRDye 700DX) and 690-nm red light has shown promising results, with a 43% objective response rate (ORR) in a phase IIa trial for recurrent head and neck squamous cell carcinoma. This study aimed to evaluate the safety and efficacy of combining photoimmunotherapy with nivolumab for advanced gastric cancer.

Methods: This phase Ib open-label, single-center trial investigated the combination of photoimmunotherapy with ASP-1929 and nivolumab in patients with unresectable EGFR-positive gastric adenocarcinoma after standard chemotherapy. The dose-escalation part aimed to determine the recommended dose of laser illumination energy under endoscopy, and the expansion part assessed the safety and efficacy at the determined dose. The primary endpoint was dose-limiting toxicity (DLT), and treatment response and adverse events were evaluated.

Results: Between October 2019 and April 2022, 21 patients were enrolled. All patients had previously received at least two lines of chemotherapy, with six being refractory to anti-PD-1 therapy. No DLT was observed, and the recommended dose was 100 J/cm. Two patients achieved a partial response, and ORR was 9.5%.

Conclusion: This study demonstrated that combining endoscopic photoimmunotherapy with nivolumab is safe and feasible for advanced gastric cancer.

Trial Registry: The trial is registered in the Japanese Registry of Clinical Trials (identifier: jRCT2080224884, https://jrct.niph.go.jp/en-latest-detail/jRCT2080224884 ).