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Clarity Pharmaceuticals to Evaluate GRPr-Targeting Radiopharmaceutical in mCRPC Trial

NEW YORK – Clarity Pharmaceuticals said on Monday that it will begin evaluating its investigational radiopharmaceutical 64Cu/67Cu-SAR-Bombesin in a Phase I/II clinical trial for metastatic castration-resistant prostate cancer patients whose tumors express gastrin-releasing peptide receptor (GRPr).

The launch of the clinical trial, dubbed COMBAT, comes after the US Food and Drug Administration cleared the firm's investigational new drug application. The dose escalation study is designed to determine the safety and efficacy of 64Cu/67Cu-SAR-Bombesin among GRPr-expressing mCRPC patients who are not eligible to receive Novartis' prostate specific membrane antigen (PSMA)-directed radiopharmaceutical Pluvicto (177Lu-PSMA-617).

The radiopharmaceutical that Clarity is evaluating, SAR-Bombesin, is designed using Clarity's sarcophagine (SAR) technology, which holds copper isotopes securely in a chelator structure. According to Clarity, its chelator technology prevents copper from leaking into the body, which is not necessarily true of commercially available chelators.

The theranostic can be both a diagnostic imaging agent when it is linked to the copper-64 isotope, or a therapeutic when it includes the cell-killing copper-67 isotope. The firm is already evaluating 64Cu-SAR-Bombesin as a standalone diagnostic imaging agent in the ongoing SABRE clinical trial in the US and another trial, dubbed BOP, in Australia.

Because roughly 25 percent of mCRPC patients don't have tumors expressing PSMA and accordingly aren't eligible for Pluvicto, Clarity sees a significant unmet need for its own radiopharmaceutical. Because GRP is also expressed on other cancers including breast and ovarian cancers, Clarity also sees a role for SAR-Bombesin beyond mCRPC.

Clarity is also developing a PSMA-directed radiopharmaceutical with its SAR technology, dubbed 64Cu/67Cu SAR-bisPSMA, which the firm is currently evaluating in a Phase I/II clinical trial for PSMA-expressing mCRPC.

"The diagnostic SAR-Bombesin product has already shown utility in improving the management of disease for PSMA-negative prostate cancer patients and, given the mounting clinical and preclinical data to date, we believe that it has potential to provide this large patient population with more accurate and precise detection and treatment of disease," Alan Taylor, Clarity's executive chairman, said in a statement.