Clarity’s announces positive results of US-based COBRA prostate cancer study

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Clarity Pharmaceuticals (ASX:CU6) has announced positive results from its diagnostic 64Cu-SAR-bisPSMA trial, COBRA (NCT05249127).

The US-based COBRA study was a first-inhuman trial of 64Cu-SAR-bisPSMA in patients with biochemical recurrence (BCR) of prostate cancer (PC).

It was a multi-centre, single-arm, non-randomised, Phase 1/2 diagnostic imaging study of 64Cu-labelled SAR-bisPSMA (64Cu-SAR-bisPSMA) administered to participants with BCR of PC following definitive therapy.

According to lead investigator Dr Neal Shore MD, medical director of Carolina Urologic Research Centre, “We are very enthusiastic regarding the data from the early phase COBRA trial as 64Cu- SAR-bisPSMA was confirmed to be safe and effective in detecting PC lesions in patients with BCR who came into the study with negative or equivocal scans using SOC imaging.

"The trial demonstrates a clinical advantage of same-day and next-day imaging in detecting additional lesions as well as for potentially detecting low prostate-specific membrane antigen (PSMA) expressing or smaller lesions.

"When detecting recurrence of PC, it is important to visualise small lesions, as reliable imaging of low volume tumour burden can affect treatment decision making. In the COBRA trial, we saw that 64Cu-SAR-bisPSMA positron emission tomography (PET) informed potential changes in the treatment plan in approximately half of the patients. This makes a difference for patients who may then have insight into the location of their disease recurrence and thereby proceed to treatment of their cancer.

"We look forward to additional data readouts from the trial and presenting the results at future international medical conferences. If the data from the COBRA trial can be substantiated in a registrational Phase 3 study, and if approved by the United States Food and Drug Administration (US FDA), this PET PSMA modality will impact care for patients with PC.”

Clarity’s executive chairperson, Dr Alan Taylor, added, “We are extremely excited with the initial findings from the COBRA trial as it further substantiates the many benefits of copper-64 (64Cu) and our optimised bisPSMA product in the diagnosis of PC.

"Combined with our clinical and pre-clinical trial data to date, this further validates SARbisPSMA as a potential best-in-class PSMA agent for the diagnosis (with 64Cu) and subsequent treatment (with copper-67 [67Cu]) of PC.

"We have also seen the performance of 64Cu-SAR-bisPSMA in the real-world setting through our compassionate use program, which demonstrated the ability of 64Cu-SAR-bisPSMA to detect lesions in patients with BCR and a negative or equivocal SOC imaging (including 18F-DCFPyL and 68Ga-PSMA-11). These cases also showed a higher number of lesions and lesions with higher maximum standardised uptake values (SUVmax) on next day imaging. Therefore, we were already aware of the benefits of later-timepoint imaging, but the high number of lesions detected on same-day imaging that were negative or equivocal on SOC imaging (e.g. bone scan, CT or PSMA PET), and the almost doubling of the number of lesions with next-day imaging, is remarkable. The COBRA study now validates previous observations in a larger group of patients under trial conditions.

“Most importantly, the high rate of detection of PC in up to 80% of patients that were negative or equivocal on SOC imaging further brings to light the low sensitivity issues of current SOC imaging. We adhere to the highest standards and methods of clinical development as we pride ourselves on high quality science at Clarity. As such, the COBRA trial design was built to reflect the gold standard in clinical research and took a very conservative approach."

Dr Taylor added that the positive results from the COBRA trial will inform a Phase 3 trial in patients with BCR of PC.