The primary endpoint of this phase II study that evaluated the efficacy and safety of the investigational compound, AGS-16C3F, versus axitinib in previosuly treated patients with metastatic renal cell carcinoma (mRCC) was not met. The safety profile for each study drug was as expected, with the most commonly reported adverse events being fatigue and nausea in the AGS-16C3F arm and fatigue and diarrhea in the axitinib arm These results provide a benchmark for axitinib use in heavily pretreated patients with mRCC.
AGS-16C3F is a novel antibody-drug conjugate that targets cell-surface ENPP3 and is conjugated to a microtubule disruptive agent. Here we present findings from a phase II study of AGS-16C3F versus axitinib in metastatic renal cell carcinoma (mRCC).
Patients with mRCC of any histology and disease progression during or after their last treatment regimen were randomized 1:1 to intravenous AGS-16C3F 1.8 mg/kg every 3 weeks or oral axitinib 5 mg twice daily (starting dose). The primary objective was investigator-assessed progression-free survival (PFS) of AGS-16C3F versus axitinib (RECIST v1.1).
In the total population (N = 133), 63% (n = 84) of patients had completed the study at data cutoff (August 21, 2019). Median PFS was 2.9 months with AGS-16C3F and 5.7 months with axitinib (HR, 1.676; 95% CI, 1.107-2.537; p = .015). There were no significant differences between arms in secondary efficacy endpoints, including overall survival (13.1 months, AGS-16C3F and 15.4 months, axitinib; HR, 1.079; 95% CI, 0.681-1.707; p = .747). In the safety population (N = 131), the most commonly reported adverse events were fatigue (53%) and nausea (47%) in the AGS-16C3F arm and fatigue (57%) and diarrhea (48%) in the axitinib arm. The incidence of diarrhea was lower in the AGS-16C3F arm than in the axitinib arm (17% vs. 48%), and ocular toxicities were more frequent in the AGS-16C3F arm than in the axitinib arm (44% vs. 26%).
The investigational compound, AGS-16C3F, did not meet the primary endpoint of this trial. These study results provide a benchmark for axitinib use in heavily pretreated patients with mRCC.

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