Argos Therapeutics Inc. recently announced that updated results from an open label Phase 2 study of its Arcelis™ immunotherapy, AGS-003, in combination with sunitinib in patients with unfavorable risk, metastatic renal cell carcinoma (mRCC), had demonstrated prolonged survival. Based upon these results, the company is planning to initiate the international Phase 3 ADAPT study. Data from the open-label Phase 2 study were presented in a poster and oral session at the 2012 ASCO Genitourinary Cancers Symposium in San Francisco.
Twenty-one patients with newly diagnosed, metastatic clear cell RCC were enrolled in this Phase 2 study. Following nephrectomy or metastasectomy to harvest tumor mRNA, autologous monocytes were collected by leukapheresis, in order to produce RNA-loaded dendritic cells specific to each patient’s disease. Treatment consisted of six-week cycles of sunitinib, four weeks on and two weeks off, plus AGS-003, which was administered as an intradermal injection every three weeks for five doses, and then every 12 weeks until progression in combination with sunitinib. Immune responses were evaluated at baseline and following five doses of AGS-003 using multiparametric flow cytometry, to assess the induction of anti-tumor, CD28+ memory T cell responses.
Results indicate that multiple partial responses were observed with this combination regimen, while 11 of 15 (73%) patients with serial immune assessments demonstrated increases in their CD28+ memory T cells. These immune responses correlated directly with prolonged survival in this study. Overall, the median progression-free survival was 11.2 months and estimated Kaplan-Meier median overall survival was 29.3 months in this study, based upon follow-up through January 2012. In addition, AGS-003 was well tolerated in combination with sunitinib, with no immunotherapy related serious adverse events observed.