Effect of prior thoracic radiotherapy on prognosis in relapsed small cell lung cancer patients treated with anlotinib: a subgroup analysis of the ALTER 1202 trial

Background In ALTER 1202, anlotinib prolonged the progression-free survival (PFS) and overall survival (OS) of patients with relapsed small cell lung cancer (SCLC). The aim of this study was to explore the effect of front-line thoracic radiotherapy (RT) on the benefits of anlotinib as a third-line-or-beyond treatment. Methods This was a subgroup analysis of a multicenter, randomized, double-blind, placebo-controlled phase 2 trial (ALTER 1202). The participants were divided into RT (previous thoracic RT) and non-RT subgroups. The outcomes included PFS, OS, objective response rate (ORR), disease control rate (DCR), and safety. Results In the ALTER 1202 trial, 68 participants (anlotinib, n=46; placebo, n=22) received RT and 51 participants (anlotinib, n=35; placebo, n=16) did not. PFS was longer for anlotinib versus placebo in both the RT (5.49 vs. 0.69 months; P<0.001) and non-RT (2.83 vs. 0.76 months; P<0.001) subgroups. In the RT subgroup, the OS was longer for anlotinib vs. placebo (9.49 vs. 4.90 months; P=0.039). No differences were found in the ORR, but the DCR was higher in the anlotinib arm of the RT subgroup compared with the placebo arm (73.9% vs. 9.1%, P<0.001) and the non-RT subgroup (68.6% vs. 18.8%; P=0.002). Conclusions In relapsed SCLC patients with previous thoracic RT, anlotinib might have DCR, PFS, and OS benefits compared with placebo. In those without previous thoracic RT patients, anlotinib might have DCR and PFS benefits compared with placebo. The safety was similar between anlotinib and placebo groups.