Clinical stage radiopharmaceutical company Clarity Pharmaceuticals (ASX:CU6) has begun its Cu 64/Cu 67 SAR-Bombesin Phase I/II trial in metastatic castrate-resistant prostate cancer (mCRPC) with the opening of the first site at BAMF Health in Michigan, US.

The company reports COMBAT (Copper-7 SAR Bombesin in metastatic castrate-resistant prostate cancer, NCT05633160) is a dose escalation and cohort expansion trial for up to 38 participants.

The trial aims to determine the safety and efficacy of Cu-SAR-Bombesin in participants with gastrin-releasing peptide receptor (GRPr) expressing mCRPC in patients who are ineligible for therapy with Lu PSMA-617.

“COMBAT is our third theranostic trial in the US and a second theranostic trial in prostate cancer”

Commenting on the trial, Clarity Pharmaceuticals Executive Chairman Dr Alan Taylor said: “We are excited to initiate our first theranostic clinical trial of the SAR-Bombesin product.

COMBAT is our third theranostic trial in the US and a second theranostic trial in prostate cancer, an indication that continues to have high unmet need. In the VISION trial for the recently approved Lu PSMA-617, median overall survival increased from about 11 months on standard of care therapy to about 15 months with Lu PSMA-617 plus standard of care.

Despite this, 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. 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.

We look forward to progressing the COMBAT trial and building on the compelling data from our preclinical studies as well as from 3 diagnostic trials with this product.

SAR-Bombesin has already resulted in improvements to the management of prostate cancer for patients with PSMA-negative or low PSMA expressing tumours and we hope to confirm its safety and efficacy in the theranostic trial.”

Clarity is a clinical stage radiopharmaceutical company focused on treating cancer in children and adults using its proprietary sarcophagine (SAR) technology platform, which holds copper isotopes inside a cage-like structure called a chelator. SAR-Bombesin is a Targeted Copper Theranostic (TCT) that can be used with isotopes of copper 64 for imaging and copper 67 for therapy.