Significant tumour response to neoadjuvant therapy in high-risk non-metastatic prostate cancer

The first results of the phase 2 ACDC-RP trial show that 44% of patients with high-risk, clinically non-metastatic prostate cancer achieved either pathological complete response (pCR) or minimal residual disease (MRD) after neoadjuvant therapy with leuprolide plus abiraterone with or without cabazitaxel.

High-risk, non-metastatic prostate cancer has a significant risk of recurrence when treated with unimodal therapy. The utility of neoadjuvant therapy prior to radical prostatectomy has yet to be defined. Therefore, the ACDC-RP trial (NCT02543255) investigated the use of abiraterone acetate/prednisone (AAP) and leuprolide with or without cabazitaxel prior to radical prostatectomy in patients with high-risk, clinically non-metastatic prostate cancer. Prof. Neil Fleshner (Princess Margaret Cancer Centre, Canada) presented the first results [1].

Enrolled were 77 patients, who were randomised 1:1 to 24 weeks (6 cycles) neoadjuvant therapy with AAP/leuprolide/cabazitaxel (Arm A) or AAP/leuprolide (Arm B). The primary objective was to compare the rate of pCR or MRD between treatment arms. MRD was defined as ≤5% of prostate volume involved by tumour.

The addition of cabazitaxel did improve pCR/MRD rates. Across both treatment arms, 31 (44%) men achieved either pCR or MRD; 5 men had pCR (2 in Arm A, 3 in Arm B) and an additional 26 men exhibited MRD (14 in Arm A, 12 in Arm B). Kaplan-Meier analysis demonstrated no difference in biochemical-free survival rate between the 2 treatment groups. Patients who achieved a pCR/MRD experienced significantly longer biochemical-free survival.

Prof. Fleshner concluded that it is now important to learn what determines pCR and MRD in these patients. Genomic efforts are underway to determine predictors of response.

1. Fleshner NE, et al. Randomized phase II trial of neoadjuvant abiraterone plus or minus cabazitaxel in high-risk prostate cancer: ACDC-RP. Abstract 224, ASCO GU 2022, 17–19 February.

 

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Posted on 8 April, 20228 April, 2022