VISION and TheraP: Comparing Eligible Patient Outcomes in mCRPC

The TheraP and VISION trials both examined the use of 177Lu-PSMA617 in patients with progressive metastatic castration resistant prostate cancer (mCRPC); however, the stricter criteria in the TheraP trial doubled the screening failure rate compared to the VISION trial, at 28% versus 12.6%.

The TheraP trial also set a high threshold for prostate specific membrane antigen (PSMA) expression on PSMA positron emission tomography (PET) and utilized fludeoxyglucose F18 (FDG) PET to exclude FDG-avid or non-PSMA-avid disease, while the VISION trial used PSMA PET with a lower threshold of PSMA expression.

At the 2024 American Society of Clinical Oncology Genitourinary Cancers Symposium, a retrospective cohort study presented by Ridvan Arda Demirci, MD, examined VISION-eligible patients to compare the outcomes of patients who were also TheraP-eligible (TheraP-E) to TheraP-ineligible (TheraP-I). The prognostic value of FDG-PET phenotyping was also analyzed.

The study analyzed 46 VISION-eligible patients with mCRPC who underwent at least 1 cycle of LuPSMA and had both PSMA- and FDG-PET within 1 month of each other between June 2022 and January 2023. Patients were blindly classified as TheraP-E or TheraP-I, and characteristics including total tumor volume (TTV), SUVmean and SUVmax along with outcomes including PSA decline of ≥50% relative to baseline (PSA50), PSA-progression-free survival (PSA-PFS), and overall survival (OS) were compared between the groups.

With a median follow-up of 10 months, 14 (30%) patients in the TheraP-I group had lower PSMA-PET SUVmean and SUVmax compared to TheraP-E patients (5.6 vs 8.8 and 23 vs 53, P<.001 for both groups), while other parameters including PSMA TTV and FDG parameters (SUVmax, SUVmean and TTV) were not statistically different.

Patients in the TheraP-I group had lower PSA50 response (21% vs 56%, P=.029), but PSA-PFS and OS were not significantly different compared to TheraP-E patients. A total of 37 (80%) patients who were assessed as FDG-avid had an increased risk of death compared to non-FDG-avid counterparts.

In this VISION-eligible patient population undergoing LuPSMA treatment, TheraP ineligibility was associated with worse PSA response, but no significant difference was noted in PSA-PFS or OS. Further investigation into the VISION study’s inclusion criteria utilizing a larger sample size is needed.