Clarity’s theranostic prostate cancer trial progresses at the highest dose level cohort

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Clinical-stage radiopharmaceutical company Clarity Pharmaceuticals (ASX:CU6) has announced the successful completion of the first stage of cohort three of the Phase 2/2a theranostic trial, SECuRE.

The trial is evaluating Clarity's 64Cu/67CuSAR-bisPSMA in patients with metastatic castrate-resistant prostate cancer (mCRPC), where three participants have been treated at the highest dose level of 12GBq.

The company said no adverse events were reported for 64Cu-SAR-bisPSMA. Only one adverse event was reported and related to the 12GBq cycle of 67Cu-SAR-bisPSMA in one of the three participants, which was a grade one decrease in neutrophil count. The company said the patient has fully recovered.

The Safety Review Committee has recommended that the trial continue with the additional three participants as planned in cohort three.

Clarity's 64Cu-SAR-bisPSMA is used to visualise PSMA-expressing lesions and select candidates for subsequent 67Cu-SAR-bisPSMA therapy.

SECuRE is a multi-centre, single-arm, dose-escalation trial with a cohort expansion involving up to 44 patients in the US.

The company said the trial aims to determine the safety and efficacy of 67Cu-SAR-bisPSMA for the treatment of prostate cancer.

Clarity’s executive chairperson, Dr Alan Taylor, said, “We are excited by the PSA declines seen in almost all patients to date in cohorts 2 and 3 from just a single cycle. This result is also seen in patients that have been heavily pre-treated and have failed many other therapies that are either commercial or investigational. Moreover, the safety profile is very favourable and there have been no DLTs reported to date.

“SAR-bisPSMA was designed to be a best-in-class PSMA product as, unlike all other PSMA products in the market, it has dual targeting. The product was optimised to address the challenges of low uptake and retention in lesions that the first generation of PSMA products suffer from, and in both pre-clinical and clinical development to date we have observed two to three times the uptake of SAR-bisPSMA in lesions, followed by retention in lesions out to at least 96 hours. So far, the higher uptake and retention of product, coupled with the advantageous properties of copper-67, has shown quite impressive responses measured by PSA reductions in patients from single cycles of product to date."