Fifth Patient Achieves Undetectable Disease in 67Cu-SAR-bisPSMA Prostate Cancer Trial

Another participant with metastatic castration-resistant prostate cancer (mCRPC) in the Cohort Expansion Phase (Phase II) of the SECuRE trial (NCT04868604) achieved undetectable disease as assessed by prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) positron emission tomography (PET). Undetectable disease by PSA was achieved after the first cycle, followed by a negative PSMA PET after the second cycle of 67Cu-SAR-bisPSMA at 8 GBq per cycle.

The participant is a 76-year-old man who was initially diagnosed with prostate cancer 15 years ago. He had radical prostatectomy to treat the primary disease and radiotherapy for local recurrence, having progressed to metastatic disease in 2020. Previous systemic anti-cancer treatments included an androgen receptor pathway inhibitor (ARPI) and androgen deprivation therapy (ADT). In 2025, the disease progressed further, and he was enrolled into the Cohort Expansion Phase of the SECuRE study with a baseline PSA of 3.25 ng/mL.

Seven weeks after his first cycle of 67Cu-SAR-bisPSMA, this participant achieved undetectable PSA levels. He proceeded to receive one more cycle of 67Cu-SAR-bisPSMA, and no disease was observed on PSMA PET following the second dose. This participant exhibited mild (Grade 1) related adverse events, including altered taste, dry eyes, eye pain, fatigue and salivary gland soreness (all resolved except fatigue). No haematological or renal adverse events were observed to date.

This new case represents the fifth participant to achieve undetectable disease by radiographic assessment following 67Cu-SAR-bisPSMA treatment in Clarity Pharmaceuticals' SAR-bisPSMA theranostic program. This includes 3 participants who received up to four cycles of 8 GBq, and 2 participants who received up to three cycles of 12 GBq.

A previously reported participant from the Cohort Expansion Phase who achieved undetectable disease following three cycles of 8 GBq 67Cu-SAR-bisPSMA treatment continues to demonstrate undetectable PSA, with no disease identified on his latest PET conducted 1 month after the administration of the fourth cycle in February 2026. Following the first three cycles of 67Cu-SAR-bisPSMA, the participant exhibited mild (Grade 1) related adverse events, most of which were gastrointestinal events, with no haematological or renal adverse events. No new safety signals have been observed during and since the administration of the fourth cycle to date.

The SECuRE trial will continue enrolment into the Cohort Expansion Phase with planned completion of recruitment in 2026. Phase III registrational trial planning is ongoing based on data generated to date.