ATLAS trial of adjuvant axitinib in patients with renal cell carcinoma: subgroup analyses with focus on axitinib dosing and racial groups

BACKGROUND: The ATLAS trial, investigating adjuvant axitinib versus placebo in renal cell carcinoma (RCC), was stopped for futility at a preplanned interim analysis. We report subgroup outcome analyses by ethnicity, time on treatment, dose modification and toxicity. PATIENTS AND METHODS: Patient demographics, baseline characteristics, treatment duration and exposure and safety were analysed for Asian versus non-Asian patients treated with axitinib versus placebo. Disease-free survival (DFS) was analysed by ethnicity, treatment duration (≥1 versus <1 year), dose modification and adverse event (AE) grade. RESULTS: No DFS benefit was observed for Asian {hazard ratio (HR) 0.883 [95% confidence interval (CI) 0.638-1.220]} or non-Asian [HR 0.828 (95% CI 0.490-1.400)] patients treated with axitinib or placebo. Fewer Asian versus non-Asian patients were in the highest-risk group in axitinib (51.9% versus 72.3%) or placebo (51.5% versus 66.0%) arm. Highest-risk patients in both subgroups had no DFS benefit with either treatment. More axitinib-treated Asian versus non-Asian patients had dose reductions due to AEs (58.8% versus 46.0%; P = 0.028). Asian patients experienced more nasopharyngitis but less fatigue or asthenia than non-Asians. Among Asian patients, proteinuria, hypothyroidism, nasopharyngitis, and hypertension were more common in Japanese patients than Korean patients and more common in Korean patients than Chinese patients. Patients receiving axitinib >1 year versus ≤1 year did not have different DFS: HR 0.572 (95% CI 0.247-1.327); P = 0.1874. Compared with patients on stable axitinib dose, DFS was longer in patients with dose reduction [HR 0.458 (95% CI 0.305-0.687); P = 0.0001], whereas DFS was not different in those with dose escalation [HR 1.936 (95% CI 0.937-3.997); P = 0.0685]. DFS was not different in patients experiencing grade ≥2 versus <2 AEs within 6 months of initiating axitinib: HR 0.885 (95% CI 0.419-1.869); P = 0.7488. CONCLUSIONS: Asian versus non-Asian subgroup analysis revealed differences in AE experience and drug exposure. There were no DFS differences based on ethnicity or treatment duration, but axitinib dose reduction led to longer DFS.