Interferon alfa-2a and 13-cis-retinoic acid in renal cell carcinoma: antitumor activity in a phase II trial and interactions in vitro.
Academic Article
Overview
abstract
PURPOSE: A phase II trial of interferon alfa-2a (IFN) and 13-cis-retinoic acid (CRA) was conducted in patients with renal cell carcinoma (RCC). In vitro studies were performed to investigate potential mechanisms of interaction. PATIENTS AND METHODS: Forty-four patients were treated. IFN was given daily at 3 MU and escalated to 6 and 9 MU if tolerated. The dose of CRA was 1 mg/kg/d. The effects of combining CRA and IFN on the proliferation of five RCC cell lines were examined, and retinoid sensitivity was correlated to the expression of retinoic acid receptors. RESULTS: Thirteen (30%) of 43 assessable patients achieved a major response (three complete and 10 partial). Responding sites included bone metastases and renal primary tumors. Seven responding patients remain progression-free at 10+ to 19+ months. The response proportion was higher than in our prior experience with IFN, which was 10% in 149 patients. Eleven of 12 renal cancer cell lines were resistant to CRA alone; one, SK-RC-06, showed 90% inhibition of cell growth. CRA augmented the antiproliferative effect of IFN in several IFN-sensitive cell lines, but not in IFN-resistant lines. Northern blot analysis showed that expression of retinoic acid receptor-beta (RAR-beta) was repressed and not induced by retinoic acid in retinoic acid-insensitive RCC lines. However, RAR-beta expression was induced by retinoic acid in SK-RC-06 cells. CONCLUSION: IFN and CRA showed antitumor activity in patients with advanced RCC, and the proportion and nature of response suggested CRA added therapeutic benefit to IFN. A phase III randomized trial of IFN plus CRA versus IFN alone and a phase II trial of single-agent CRA have been initiated.
