On June 11, 2026 PeptiDream Inc., a public Kanagawa, Japan-based biopharmaceutical company (President: Patrick C. Reid, hereinafter "PeptiDream") reported the dosing of the first patient in a first-in-human imaging study of 64Cu-PD-29875 targeting Claudin 18.2 ("CLDN18.2").
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This clinical research is a first-in-human Phase 0 imaging study*¹ of 64Cu-PD-29875. In this study, 64Cu-PD-29875 is being evaluated for the safety, pharmacokinetics, tumor uptake, and dosimetry using PET/CT imaging in patients with gastric cancer, including gastroesophageal junction cancer. PET imaging with 64Cu-PD-29875 will enable assessment of its diagnostic performance and provide insights into its potential as a paired radiotherapeutic*² agent when labeled with therapeutic radioisotopes.
CLDN18.2 is a member of the claudin family of proteins that form tight junctions in epithelial tissues. While it is primarily expressed in gastric epithelial cells in normal tissues, it has been reported to be highly expressed in a variety of solid tumors, including gastric cancer, esophageal cancer, pancreatic cancer and lung adenocarcinoma. It is regarded as an attractive molecular target for both cancer diagnosis and therapy.
PD-29875 is a macrocyclic peptide discovered using PeptiDream’s proprietary PDPS technology and further optimized through in vivo imaging*³ and efficacy studies conducted at PDRadiopharma, a wholly owned subsidiary of PeptiDream.
In this clinical research, PD-29875 is labeled with the diagnostic radioisotope 64Cu to generate PET imaging data. These data are expected to provide early insights into the diagnostic performance, inform the likelihood of therapeutic benefit when labeled with therapeutic radioisotopes, and support the design of subsequent clinical studies, thereby significantly accelerating clinical development.
Patrick C. Reid, President & CEO of PeptiDream commented: "The initiation of clinical dosing for PD-29875 marks an important step in realizing our vision of building a differentiated radiotheranostics platform. As our second wholly owned radiopharmaceutical program, PD-29875 targets CLDN18.2, a highly promising oncology target, and exemplifies the strength of our peptide discovery engine. By advancing both a 225Ac-labeled therapeutic and 64Cu-labeled diagnostic as part of our integrated radiotheranostic approach, we are accelerating our mission to deliver next-generation precision radiopharmaceuticals for patients with cancer."
PD-29875 was adopted by the Japan Agency for Medical Research and Development (AMED) as part of the "Practical Research for Innovative Cancer Control" and received funding support from AMED in 2024.
(Press release, PeptiDream, JUN 11, 2026, View Source [SID1234666586])