Baseline anti-SEA/E-120 and plasma concentration of Nap Day 1 at 1h in different territories.

Cytokine response after Nap treatment in ITT and the subgroup SG patients during cycle 1 (week 1), cycle 2 (week 9) and cycle 3 (week 17). IL-2 (A). IL-6 (B). IL-10 (C). IFN-ϒ (D). TNF-α (E). Geomean{plus minus}SE is depicted.

Anti-SEA/E-120 vs exposure of Nap. Concentration of Nap after Nap at day 1 of treatment. Moving median of 8 overlapping subgroups of patients with different baseline anti-SEA/E-120 (pmol/mL). Median{plus minus}SE is depicted.

Anti-SEA/E-120 vs IL-2 day 1 3h. Concentration of induced IL-2 after Nap at day 1 of treatment. Moving median of 8 overlapping subgroups of patients with different baseline anti-SEA/E-120 (pmol/mL). Median{plus minus}SE is depicted.

Cox regression analysis with interaction between baseline covariates and treatment.

Anti-SEA/E-120 concentration in ITT and the subgroup SG at baseline and immediately before Nap cycle 2 (week 9), before Nap cycle 3 (week 17) and at week 25. Median{plus minus}SE is depicted.

Cox regression analyses with three way interaction stratified by either MSKCC or HENG risk.

Overlapping anti-SEA/E-120 windows in Moving median and adapted Subpopulation Treatment Effect Pattern Plot (STEPP) analysis. Anti-SEA/E-120 by blocks where min, median and max values are depicted

Abstract Purpose: To prospectively determine the efficacy of naptumomab estafenatox (Nap) + IFNα versus IFN in metastatic renal cell carcinoma (RCC). Experimental Design: In a randomized, open-label, multicenter, phase II/III study, 513 patients with RCC received Nap (15 μg/kg i. v. in three cycles of four once-daily injections) + IFN (9 MU s.c. three times weekly), or the same regimen of IFN monotherapy. The primary endpoint was overall survival (OS). Results: This phase II/III study did not meet its primary endpoint. Median OS/PFS for Nap + IFN patients was 17.1/5.8 months versus 17.5/5.8 months for the patients receiving IFN alone (P = 0.56; HR, 1.08/P = 0.41; HR, 0.92). Post hoc exploratory subgroup and trend analysis revealed that the baseline plasma concentrations of anti-SEA/E-120 (anti-Nap antibodies) for drug exposure and IL6 for immune status could be used as predictive biomarkers. A subgroup of patients (SG; n = 130) having concentrations below median of anti-SEA/E-120 and IL6 benefitted greatly from the addition of Nap. In SG, median OS/PFS for the patients treated with Nap + IFN was 63.3/13.7 months versus 31.1/5.8 months for the patients receiving IFN alone (P = 0.02; HR, 0.59/P = 0.02; HR, 0.62). Addition of Nap to IFN showed predicted and transient immune related AEs and the treatment had an acceptable safety profile. Conclusions: The study did not meet its primary endpoint. Nap + IFN has an acceptable safety profile, and results from post hoc subgroup analyses showed that the treatment might improve OS/PFS in a baseline biomarker-defined RCC patient subgroup. The results warrant further studies with Nap in this subgroup. Clin Cancer Res; 22(13); 3172–81. ©2016 AACR.

3073 Background: Naptumomab estafenatox/ANYARA (Nap) is a fusion protein of an antibody (5T4) and a superantigen (SEA/E-120). After phase I studies (Borghaei. J Clin Oncol. 2009, 27:4116) a prospective, randomized phase II/III trial of Nap + IFN-α (A) vs IFN-α (I) was conducted. Methods: Patients (pts) with RCC were randomized in an open label study to receive A or I. The primary endpoint was OS. Secondary endpoints were PFS, response rate and safety. Baseline (bl) plasma IL-6 was predictive of pazopanib (Tran. Lancet Oncol. 2012, 13:827) and MVA-5T4 vaccine (Harrop. Cancer Immunol Immunother. 2012, 61:2283) benefit in RCC pts. IL-6 and anti-SEA/E-120 antibodies (a-S) were analyzed. A subgroup SG1 had bl levels below median for IL-6 (<7 pg/ml) and a-S. Another subgroup SG2 had IL-6 below 13 pg/ml (Tran. Lancet Oncol. 2012, 13:827) and excluding upper quartile of a-S according to phase 1 levels (Borghaei. J Clin Oncol. 2009, 27:4116). Results: From 5/2007 to 10/2010 513 pts were treated (ITT) with a median follow-up time for censored pts of 43 months. Unexpectedly, pts in certain territories had increased bl a-S (median of 61 pmol/ml in Russia vs 34 in UK). The table summarizes efficacy results. The primary endpoint was not met. Multivariate analysis adjusted for risk scores and subsequent TKI usage verified Nap benefit in pts with low IL-6 and normal a-S. Nap was well tolerated. Pyrexia (A:46%/I:18%), nausea (21%/11%), back pain (18%/6%), vomiting (16%/7%) and chills (12%/4%) were more common after Nap. Conclusions: The study did not meet primary endpoint. In pts with low IL-6 and normal levels of a-S, addition of Nap to IFN-α improves OS and PFS. The results warrant further studies with Nap in sequence or combo with e.g. TKIs in this subgroup. More generally, as bl IL-6 appears to be prognostic and predictive of outcome on treatment with TKIs and immunotherapies this may be a stratification factor for RCC studies. Clinical trial information: NCT00420888. [Table: see text]