AUA 2024: Identifying The Optimal Candidate for Concomitant Androgen-Deprivation Therapy Among Patients Receiving Metastasis-Directed Therapy For Positive PSMA PET and Primary or Secondary Biochemical Recurrence from Prostate Cancer

(UroToday.com) The 2024 American Urological Association (AUA) annual meeting held in San Antonio, TX between May 3 and May 6, 2024, was host to the advanced prostate cancer moderated poster session. Dr. Elio Mazzone presented data from a cohort of 383 patients who underwent PSMA-PET staging for biochemical recurrent prostate cancer following radical prostatectomy with or without radiation therapy at a single institution. Their objective was to delineate the optimal candidates for concomitant androgen deprivation therapy (ADT) among patients undergoing metastasis-directed therapy (MDT) for positive PSMA-PET and primary or secondary biochemical recurrence from prostate cancer.

The study included patients who had undergone radical prostatectomy (RP) with or without salvage radiation therapy, adjuvant radiation therapy was not permitted. From 2016 to 2023, 383 patients who had undergone PSMA-PET for biochemical recurrence were identified. Among these, the analysis focused only on patients with positive PSMA-PET who underwent MDT (n=120). Of the MDT-treated cohort, 57 patients were experiencing a primary biochemical recurrence and 63 a secondary biochemical recurrence. MDT in this cohort comprised stereotactic ablative radiation therapy (SABR) administered to positive PSMA-PET spots, irrespective of their location (nodes, bones, or visceral areas). The primary study outcome was clinical recurrence, defined as detection of new metastases on PSMA-PET scan. following treatment.

Dr. Mazzone reported that among the 120 patients included in the study, 78 (65%) received concomitant ADT. There were no discernible differences between patients treated with ADT and those who were not, suggesting that the groups were well balanced. The 2-year clinical recurrence-free survival rate was 75%. Utilizing multivariable Cox regression analyses, they explored the relationship between the type of biochemical recurrence (primary/secondary), concomitant ADT MDT, and clinical recurrence. The multivariable analysis revealed that patients experiencing secondary biochemical recurrence had significantly higher clinical recurrence rates (HR, 2.87; p<0.001).

The investigators employed regression tree analysis (RTA) to predict 2-year clinical recurrence and stratified patients into risk groups based on the location of PSMA-PET spots (pelvic vs. non-pelvic nodes or distant metastases) and the number of PSMA spots. The RTA successfully identified three risk groups with good discrimination accuracy (c-index 77%). The 2-year risk of recurrence varied significantly according to the number of PSMA spots, location of the PSMA spots, and the type of BCR (primary or secondary). Risk groups are shown below for the cohort with primary (A) and secondary (B) BCR.  

When patients were stratified into risk groups, only two groups of patients benefited from ADT, regardless of their disease characteristics and the type of BCR (primary or secondary):

  • Patients with ≥2 pelvic nodal spots (HR, 0.78; p=0.002)
  • Patients with non-pelvic nodes or distant metastasis (HR, 0.40; p=0.03)

Dr. Mazzone summarized his presentation concluding:

Patients with biochemically recurrent prostate cancer with positive PSMA-PET who are candidates for MDT, benefit from concomitant ADT when:

  • They have ≥2 nodal or distant PSMA spots either in the case of primary or secondary BCR after RP. 

Presented by: Elio Mazzone, MD, PhD, Urologic oncologist, Vita-Salute San Raffaele University.

Written by: Julian Chavarriaga, MD – Society of Urologic Oncology (SUO) Clinical Fellow at The University of Toronto, @chavarriagaj on Twitter during the 2024 American Urological Association (AUA) Annual Meeting, San Antonio, TX, Fri, May 3 – Mon, May 6, 2024.