Long-Term Efficacy and Tolerability of Abdominal Once-Yearly Histrelin Acetate Subcutaneous Implants in Patients with Advanced Prostate Cancer

Abstract EN

Objectives.

Long-term assessment of the efficacy and tolerability of subcutaneous abdominal histrelin acetate implants that have been inserted for more than two years.

Materials and Methods.

Retrospective data collected over a six-year period at a single center from charts of 113 patients who received the subcutaneous abdominal histrelin acetate implant.

Results.

Following insertion of the first implant, 92.1% and 91.8% of patients had a serum testosterone level of ≤30 ng/dL at 24 and 48 weeks, respectively.

Serum testosterone levels remained at <30 ng/dL for 96% of patients at two years and for 100% of patients at 3, 4, and 5 years.

The testosterone levels remained significantly less than baseline ( P < 0.05 ) .

Six patients (5.3%) had androgen-independent progression when followed up on the long term, increasing the mean serum PSA at 3, 4, and 5 years to 35.0 µg/L ( n = 22 ) , 30.7 µg/L ( n = 13 ) , and 132.9 µg/L ( n = 8 ) , respectively.

The mean serum PSA was significantly greater than baseline during these years ( P < 0.05 ) .

Eight patients (7.1%) experienced minor, but not serious, adverse events from the histrelin acetate.

Conclusion.

Subcutaneous abdominal histrelin acetate implants are an effective long-term and well-tolerated administration method for treating patients with advanced prostate cancer.