Clinical study of RU 23908 (nilutamide) in prostatic cancer

To investigate the efficacy and the safety of RU23908 for the treatment of prostatic cancer, an early phase 2 study with the oral administration of 150 or 300 mg daily was performed in 47 patients with stage C or D prostatic cancer at 15 institutions from April 1987 to June 1988. Forty patients were evaluable for efficacy. Concerning the effect on the object lesion, the results of the overall evaluation revealed that complete or partial response (CR + PR) was obtained in 34 of the 40 cases (85.0%). As to the effect classified by site, CR + PR were observed in 35 out of the 40 cases with primary lesion (87.5%), in 10 of the 22 cases with bone metastasis (45.5%), in 5 of the 6 cases with lymph node metastasis (83.3%) and CR was observed in one case with lung metastasis. In the PAP evaluation, 33 out of the 34 cases were judged to be CR + PR (97.1%). The improvement rate of clinical symptoms was 88.9% for bone pain, 83.3% for dysuria and 45.5% for performance status. Adverse reactions were observed in 29 of the 47 cases (61.7%) investigated and 7 cases (14.9%) were withdrawn. During the study period of 12 weeks and the subsequent period of continued administration, 6 cases (12.8%) and 2 possible cases of interstitial pneumonia were diagnosed. From the above results, the treatment of prostatic cancer with RU23908 150 mg/day or 300 mg/day in combination with surgical castration showed an excellent clinical effect compared to conventional endocrine therapy, but has a problem of safety. Therefore, this drug may be expected to be a highly useful therapeutic drug, if safely is improved in the future by reviewing the dose.