The effect of cytoreductive radiofrequency ablation (cRFA) on results of therapy with sunitinib or interferon-alpha (IFN) in metastatic renal cell carcinoma (RCC) patients with a small primary tumor.

Abstract

414 Background: At least 5% of the patients (pts) with small primary RCC initially present with metastasis. The main objective of this trial was to evaluate the role of cRFA in metastatic RCC pts with small primary tumor treated with immuno- or targeted therapy. Methods: Three parallel single-arm prospective studies were conducted. Eligibility criteria were nearly identical for all trials, and included histopathologically confirmed RCC; metastatic measurable disease; size of primary tumor ≤5 cm; good prognosis by MSKCC model; no previous therapy. Study 1: Pts were treated with percutaneous cRFA under CT guide and following IFN, 9 MIU, s.c, 3 tiw. Study 2: Pts received cRFA and following sunitinib in repeated 6-week cycles of 50 mg/day for 4 weeks, followed by 2 weeks off. Study 3: Pts with unresected primary RCC received sunitinib alone. The primary endpoint was a 33% increase in progression-free survival (PFS) over expected 5 months in study 1 and over expected 11 months in studies 2-3 (power 80%; significance .05). Sample size was 38 pts for each study. Results: Studies were comparable by baseline patient characteristics (age, gender, histology, ECOG PS, number of metastatic sites, primary tumor size). Efficacy data for 114 evaluable pts showed an objective response rate (ORR) of 8% (95% CI 4.5, 10.5) for study 1, 28.9% (95% CI 15.2, 34) for study 2, and 31.6% (95% CI 20.3, 38.9) for study 3; median PFS of 9.1 (95% CI 6.9, 10.2), 13.4 (95% CI 9.8, 14), and 12.7 (95% CI 11.3, 13.5) months for studies 1-3, respectively. ORR and PFS were significantly higher in sunitinib trials comparing with study 1 (P<.01 all differences); no differences were found between studies 2 and 3 (ORR, P=.1; PFS, P=.6). The study 1 met its primary end point, showing that PFS was significantly increased. There were no unexpected toxicities of medical treatment and complications of cRFA. Conclusions: cRFA is a safe and effective approach for select patients with metastatic RCC treated with immunotherapy. Cytoreductive ablative technique did not improve PFS in pts treated with sunitinib. Sunitinib was effective in metastatic RCC pts with unresected small primary tumor.