Clarity Pharmaceuticals says SAR-bisPSMA detects PC lesions in the 2-millimetre range

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Clinical-stage radiopharmaceutical company Clarity Pharmaceuticals (ASX:CU6) has shared additional data from its diagnostic Cu-SAR-bisPSMA trial, COBRA.

COBRA was a multi-centre, single-arm, non-randomised, Phase 1/2 diagnostic study of 64Cu-SAR-bisPSMA administered to participants with biochemical recurrence (BCR) of prostate cancer (PC) following definitive therapy and who had a negative or equivocal standard of care (SOC) scan at screening.

The trial's primary objectives were to investigate the safety and tolerability of 64Cu-SAR- bisPSMA and its ability to detect the recurrence of PC correctly.

Clarity said 64Cu-SAR-bisPSMA was able to detect much smaller lesions than anticipated, including a lesion with a diameter of less than 2 milimetres. It said this compares favourably against the current SOC PSMA PET imaging agents.

Clarity’s executive chairperson Dr Alan Taylor said, “The cornerstone of better therapy is better diagnosis, and we are incredibly excited about the substantial degree of improvement in detection of lesions with our bisPSMA product compared to SOC imaging. This difference is similar to comparing the old Hubble telescope to the new James Webb telescope, allowing us to visualise with much greater clarity, and to effectively change the paradigm of treatment to considerably improve the outcomes for patients with PC. Innovative products like 64Cu-SAR-bisPSMA may prevent many millions of men from receiving inappropriate treatments and suffering substantial debilitating side effects from surgery or other therapies.

“When combining the optimised dual PSMA targeting agent with the ideal half-life of copper-64 (64Cu), we continue to observe higher uptake and retention of 64Cu-SAR-bisPSMA in PC lesions. We believe the ability of 64Cu-SAR-bisPSMA to detect such small lesions is due to the higher uptake and retention of the product over time with high contrast (parameters measured by mean standardised uptake value [SUVmean], maximum standardised uptake value [SUVmax] and tumour-to-background ratio [TBR]). Small lesions become more readily detectable if the uptake of the product in the lesion is high and the background noise on the image is low. This effect enhances the contrast, making detect, providing clinicians with valuable information on how to best treat their patients.”