Effect of age and lenvatinib treatment on overall survival for patients with 131I-refractory differentiated thyroid cancer in SELECT (#363)
Aims: The lenvatinib progression-free survival (PFS) benefit vs placebo in the phase 3 SELECT trial of radioiodine-refractory differentiated thyroid cancer (RR-DTC) was maintained in younger ( ≤65, median 56 years) and older ( >65, median 71 years) patients. Median overall survival (OS) was not reached at data cutoff, and OS was not significantly different between lenvatinib and placebo (HR 0.73; 95% CI 0.50-1.07; P=0.103). Here we examine the effect of age on OS in SELECT.
Methods: Patients with independently verified progressive RR-DTC were stratified by region, prior VEGF-targeted therapy, and age (younger: lenvatinib, n=155; placebo, n=81 vs older: lenvatinib, n=106; placebo, n=50) and randomized 2:1 to lenvatinib or placebo. Median follow-up was 17.1 months at data cutoff; 83% of placebo-treated patients crossed over to lenvatinib following disease progression.
Results: Median OS was only reached in older placebo-treated patients (18.4 months; 95% CI, 13.3-20.3). A significant difference in OS was observed in older patients, favoring lenvatinib (HR 0.53; 95% CI 0.31-0.91; P=0.020). There was no difference in OS between older and younger lenvatinib-treated patients (HR 0.78; 95% CI 0.49-1.26; P=0.304), but there was a statistically significant difference in the placebo arm, favoring younger patients (HR 0.48; 95% CI 0.27-0.85; P=0.010). We found no statistically significant differences between the age groups to explain this difference for the following factors: baseline ECOG (lenvatinib, P=0.56; placebo, P=0.46), prior VEGF-targeted therapy (lenvatinib, P=0.270, placebo, P=0.757), patients who crossed over to lenvatinib (P=0.441), or post-SELECT anticancer therapy (lenvatinib, P=0.567, placebo, P=0.112). Older patients had a nonsignificant, larger baseline median sum of target lesions (older: 64.9 mm; younger: 58.3 mm; P=0.113).
Conclusions: Older placebo-treated patients with RR-DTC had worse OS than younger placebo-treated patients in SELECT. This effect of age was completely mitigated by lenvatinib resulting in improved OS for patients >65 years treated with lenvatinib.