NEW YORK – Clarity Pharmaceuticals said on Tuesday that it has begun a Phase I/II clinical trial of its diagnostic agent 64Cu-SAR-Bombesin and therapeutic agent 67Cu-SAR-Bombesin in certain metastatic castration-resistant prostate cancer patients.
In the trial, dubbed COMBAT, Sydney, Australia-based Clarity is evaluating a copper-64-linked PET imaging agent to identify mCRPC patients whose tumors express the gastrin-releasing peptide receptor (GRPr). Patients who have GRPr-expressing tumors then receive the copper-67-linked therapeutic version of the agent.
Clarity calls both the diagnostic and therapeutic a targeted copper theranostic, or TCT. The sarcophagine, or SAR, technology Clarity uses is meant to hold the radioactive copper isotopes inside a cage-structured chelator to prevent them from leaking into the patient's body.
The trial will include up to 38 patients who are not eligible for Novartis' prostate-specific membrane antigen (PSMA)-targeted radiopharmaceutical Pluvicto (Lu 177 vipivotide tetraxetan).
"Around a quarter of men with mCRPC do not have PSMA-expressing lesions, making it impossible to offer PSMA-targeted products as therapy for this group of patients," Clarity Executive Chairman Alan Taylor said in a statement. "As a very large proportion of prostate cancers express GRPr, SAR-Bombesin is an exciting new prospect for better treating these patients that have few therapeutic options at present in the face of a devastating diagnosis."
It is estimated that more than 80 percent of metastatic prostate cancer patients express PSMA. According to Clarity, all prostate cancers that do not express PSMA do express GRPr.