Abstract: PD24-04
Sources of Funding: None

Introduction

Abiraterone acetate (AA/P) and enzalutamide (ENZ) represent the treatment of choice in men with asymptomatic or mildly symptomatic mCRPC. Altough serial PSA measurements are required to monitor response and progression, the role of serial imaging studies is unclear in daily routine. It was the purpose of our study to evaluate the potential additional benefit of imaging to monitor the disease.

Methods

A total of 56 patients with mCRPC underwent systemic first line treatment with ENZ or AA/P after failing primary LHRH-therapy. Mean serum testosterone was 34.4 (18 – 48) ng/dl. Patients underwent analysis of the serum markers PSA, alk. Phosphatase, CRP, hemoglobine, and LDH at 3-months intervals. In addition imaging studies were repeated at 3-months intervals or in case of PSA or symptomatic progression.

Results

Mean duration of AA/P treatment is 12.7 (2-19) months and mean duration of ENZ therapy is 17.2 (3- 29) months. A PSA-response was achieved in 76% and 81% in the AA/P and the ENZ group, respectively. Beside PSA, responding patients in the AA/P group demonstrated a significant decrease in serum concentrations of LDH (367,96 225,4U/l) and alk. Phosphatase (249,59 117U/l) whereas responding pts in the ENZ group demonstrated a decrease in LDH only (339,5 228,33U/l). Median duration of PSA response is 10.8 and 11.5 months in the AA/P and the ENZ group, respectively. Despite stable serum levels of 0.6 (0.2-0.9) ng/ml and an asymptomatic status, 8 patients exhibited a significant radiographic progression in number and size of lymph node metastases (n=5) or skeletal metastases (n=3). 4 pts underwent local therapy of the progressing site by stereotactic radiation and in 4 pts treatment was switched to docetaxel.

Conclusions

Despite considerable and stable PSA-response 15% of our patients exhibited significant metastatic progression which would not have been detected without serial imaging studies. Therefore, we strongly advocate imaging studies even in the presence of stable PSA serum levels. _x000D_

Funding

None