(UroToday.com) In the Rapid Abstract Session on the first day of the American Society for Clinical Oncology (ASCO) Genitourinary Cancer Symposium 2022, Dr. Fleshner presented results of the ACDC-RP trial of neoadjuvant therapy prior to radical prostatectomy in high-risk prostate cancer. He began by emphasizing that single modality treatment (whether with a surgical or radiotherapy backbone) is associated with high rates of disease recurrence. On this basis, for patients who are opting for radical prostatectomy, the use of neoadjuvant therapy has been of substantial interest. However, to date, neoadjuvant androgen deprivation therapy (ADT) has not proven oncologic benefit. Both novel androgen axis inhibitors (such as abiraterone acetate and enzalutamide) and taxane-based chemotherapy (such as docetaxel and cabazitaxel) have proven overall survival benefits in patients with more advanced disease, including metastatic castration-sensitive and castration-resistant disease. The ACDC-RP study investigated the use of abiraterone acetate, prednisone, and leuprolide with or without cabazitaxel prior to radical prostatectomy in high-risk patients.
The authors performed a phase II randomized controlled trial, randomizing patients to receive either abiraterone acetate, prednisone, leuprolide and cabazitaxel 20 mg/m2 with peg-filgrastim 6 cycles (Arm A) or abiraterone acetate, prednisone and leuprolide (Arm B) for 6 months prior to surgery.
The primary endpoint was the rate of pathological complete response (CR) or minimal residual disease (MRD). MRD was defined as ≤5% of prostate volume involved by tumor. In this report, the authors presented surgical pathological outcomes, safety signals, and early biochemical response data.
Among 77 randomized patients, 70 completed the full course of study treatment and underwent radical prostatectomy. In terms of baseline characteristics, the mean PSA was 37 ng/mL (standard deviation 51) and 63% of patients had Gleason score 8-10.
In total, 31 (44%) men achieved either CR or MRD, 43% among men receiving abiraterone and cabazitaxel and 45% among men receiving abiraterone alone. Five men had a pathological complete response, of whom 2 were in Arm A and 3 were in Arm B. A further 26 men had evidence of MRD, of whom 15 were in Arm A and 11 were in Arm B (p=1.0). In terms of biochemical-free survival, the authors found no difference between treatment groups. However, patients who achieved a CR/MRD experienced longer BFS.
In conclusion, Dr. Fleshner emphasized that the ACDC-RP trial demonstrated a significant tumor response with intense neoadjuvant therapy, with 44% of patients exhibiting CR/MRD. However, the addition of cabazitaxel did not provide additional benefits.
Presented by: Neil E. Fleshner, MD, MPH, Division of Urologic Oncology, Princess Margaret Cancer Centre, University Health Network