Phase II Trial Shows Potential Benefit of PSMA-Targeted Fluorescent Tracer in Prostate Cancer

By: Celeste L. Dixon
Posted: Tuesday, August 1, 2023

Assessing the location and extent in real time of prostate cancer hidden from view during robot-assisted radical prostatectomy may help to achieve more complete oncologic resection. According to Henk G. van der Poel, MD, of the Netherlands Cancer Institute, Amsterdam, and colleagues, this may be accomplished with a prostate-specific membrane antigen (PSMA)-targeted fluorescent tracer called OTL78, based on the results of their first-in-patient, single-arm, phase IIa feasibility trial. These findings, which the investigators believe warrant validation in a larger cohort of patients with primary prostate cancer, were published in The Lancet Oncology.

“OTL78 can intraoperatively enhance visualization of primary prostate tumors, surgical margins, residual prostate cancer in the resection bed, and nodal metastases,” the study authors noted.

Between 2020 and 2021, the study enrolled 18 adults with PSMA PET-avid prostate cancer (International Society of Urological Pathology grade group, 2 or higher; median patient age, 69 years; median prostate-specific antigen concentration, 15 ng/mL). All 18 men underwent robot-assisted radical prostatectomy with OTL78, with 16 of the surgeries including an extended pelvic lymph node dissection.

The safety and pharmacokinetics of OTL78 were the study’s primary outcomes, and the tracer was well tolerated, reported the team: “No patient died, required a dose reduction, or required discontinuation due to drug-related toxicity.” Dr. van der Poel and co-investigators also found that the optimal dosing of OTL78 was a single intravenous infusion of 0.03 mg/kg, 24 hours prior to surgery; overall, three dose/time combinations were evaluated.

“This technique could aid in reducing tumor-positive resection margins and identifying occult nodal metastases, thus improving oncological and functional outcomes in patients with prostate cancer,” concluded the study authors.

Disclosure: The study authors’ disclosure information can be found at thelancet.com.

The Lancet Oncology