Background: Axitinib has demonstrated superior efficacy over sorafenib, in patients with clear-cell mRCC. Radiological assessment of response to VEGF TKI treatment in mRCC remains an area of research as conventional RECIST criteria might underestimate responses.

Methods: This single-arm, open-label, multicenter study evaluated the safety, efficacy, and patient-reported outcomes of axitinib in patients with previously treated clear-cell mRCC. The primary efficacy endpoint was overall objective response rate (ORR; complete + partial) as per RECIST criteria 1.1. Choi criteria were also used to assess response and results were compared with RECIST. Progression free survival, overall survival, safety and quality of life were secondary endpoints.

Results: Over a limited recruitment period, fifteen patients were enrolled, thirteen of those having had  sunitinib as prior therapy. Eleven patients had a prior nephrectomy. Median time on axitinib was 118.0 days (range, 3.5–645.0 days) and the estimated survival probability at 12 months was 57.8%. Two (13.3%) patients had an objective response per RECIST, whereas nine (60.0%) patients achieved objective response per Choi criteria. Although six patients had progressive disease based on RECIST, only three patients had progressive disease per Choi criteria. Nine (60.0%) events of progression or death occurred by the end of the study and three patients continued to receive study drug. Fatigue (33%) and diarrhoea (20%) were the most common grade ≥3, all-causality, treatment-emergent adverse events. The mean change in European Quality of Life–5 Dimensions score from baseline to end of treatment was –0.0837.

Conclusions: Safety and efficacy profiles of axitinib in this study were consistent with those seen in previous studies in patients with mRCC while generally enabling patients to maintain quality of life. The sizeable difference (13% vs 60%) observed in ORR indicates that the use of Choi criteria to assess tumor response in patients with mRCC merits further research.