Metastatic renal cell carcinoma treated with Peg-interferon alfa-2b.

Introduction: Peginterferon has an increased plasma half-life and enables a constant exposure to interferon. This modification might increase the antiangiogenic effect of the treatment and influence the efficacy. We report the results of a phase II open-label study with Peginterferon alfa-2b (Pegintron Schering-Plough) on efficacy and tolerability in patients with advanced renal cell carcinoma (MRCC).

Materials And Methods: Twenty eight patients with MRCC were treated with Peginterferon in escalating doses of 0.5 microg/kg once weekly until 2 microg/kg was reached or prohibited toxicity occurred. Lesions were evaluated according to Response Evaluation Criteria in Solid Tumors (RECIST).

Results: Thirteen patients tolerated a dose of 2 microg/kg/week. At 6 months 16 patients (57%) had disease control of which four had partial response (PR) and 12 stable disease whereas 12 (43%) had progressed. PR was only seen in the lung parenchyma or mediastinum. Median time to progression (TTP) was 8 months in all patients and 13 months for PR and SD patients. Correspondingly, median survival was 19.5 months and 28 months, respectively (seven patients received second-line treatment with tyrosine kinase inhibitor). The mean dose during long-term treatment was 1.5 and at the end of treatment 1.2 microg/kg/week. Most side effects were grade 1-2 and only two patients stopped treatment for that reason. VEGF levels in serum before and during treatment did not correlate to the therapeutic response.

Discussion: Peginterferon was well tolerated in MRCC albeit with dose modification during long-term treatment. Response pattern seems to be the same as with nonpegylated interferon. Peginterferon may be used as monotherapy in selected patients and in trials of combinations with targeted drugs.