Clarity Pharmaceuticals (ASX:CU6) achieved its recruitment target for the main group of the cohort expansion in a phase 1/2a trial that is evaluating a potential prostate cancer treatment, according to a Thursday filing with the Australian bourse.

The enrolled 16 participants with metastatic castration-resistant prostate cancer are being assessed for the efficacy and safety of up to six cycles of the company's 67Cu-SAR-bisPSMA drug candidate.

The company said recruitment remains ongoing for additional participants in the cohort expansion who will be treated with a combination of 67Cu-SAR-bisPSMA and enzalutamide.

Clarity Pharmaceuticals is already planning a registrational theranostic phase 3 trial based on preliminary results so far, said Executive Chairperson Alan Taylor.

The company's shares fell 1% in recent Thursday trade.