Estrogen, progesterone, and androgen-binding sites in renal cell carcinoma. Observations obtained in Phase II trial of flutamide.

A Phase II disease-oriented drug trial using flutamide (4'-nitro-3'trifluoro-methylisobutyranilide) 250 mg by mouth three times a day was undertaken in 28 patients with advanced, bidimensionally measurable renal cell carcinoma. Of 25 adequately treated cases, 1 (4%, 95% confidence limits 0-12%) had a partial remission lasting 9+ months, and 2 had stabilization of disease lasting 6 and 15 months, respectively. Flutamide demonstrated no significant antitumor activity in patients with disseminated renal cell carcinoma. Including patients entered in this study, 62 specimens were evaluated for steroid binding sites using a fluorescent method: 33 of 62 specimens assayed showed no hormone-binding sites, and only 12 cases had androgen binding. Of the 12 of 23 patients receiving flutamide who were biopsied and had an adequate sample for steroid-binding site determination, estrogen binding was demonstrated in 6, androgen binding in 3, and progesterone binding in 4. Since this study did not obtain a sufficient number of cases with androgen-binding positivity, the possible efficacy of flutamide in such cases cannot be excluded.