PeptiDream Announces First Dosing of Claudin18.2 Targeting Radiopharmaceutical Candidate 64Cu-PD-29875 in Patients with Gastric Cancer

• The first patient has been dosed with ⁶⁴Cu-PD-29875 in a first-in-human clinical study in patients with gastric cancer or gastroesophageal junction cancer.
• The study is designed to evaluate safety, pharmacokinetics, tumor uptake and dosimetry through PET imaging with ⁶⁴Cu-PD‑29875.
• PET imaging is expected to characterize diagnostic performance of ⁶⁴Cu-PD-29875 and generate important insights into the program’s potential as a radiotherapeutic agent when labeled with therapeutic radioisotopes.

KAWASAKI, Japan--(BUSINESS WIRE)--PeptiDream Inc., a public Kanagawa, Japan-based biopharmaceutical company (President: Patrick C. Reid, hereinafter "PeptiDream") today announced the dosing of the first patient in a first-in-human imaging study of ⁶⁴Cu-PD-29875 targeting Claudin 18.2 (“CLDN18.2”).

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.

*1: First-in-human
A study in which the drug is administered to a human for the first time is called a “first-in-human study”

*2: Theranostics
A medical approach that integrates both treatment and diagnosis by using different nuclides for diagnosis and treatment based on the same targeting molecule, such as peptides. Theranostics makes it possible to perform cancer diagnosis and treatment in an integrated manner and is expected to have benefits such as effectively selecting patients who are most likely to benefit from treatment and being able to monitor the effectiveness of treatment at any time.

*3: In vivo imaging
Observation of the behavior of administered compounds labeled with a radionuclide or other method. For example, in vivo imaging techniques can be used to visualize how a drug is distributed, metabolized, and excreted in the body when administered.