Multicenter retrospective study of selpercatinib treatment for advanced or recurrent RET fusion-positive non-small cell lung cancer in Japan.

[BACKGROUND] Selpercatinib is the current standard of care for patients with recurrent or advanced RET fusion-positive non-small cell lung cancer (RET-NSCLC). However, real-world data on selpercatinib for RET-NSCLC are extremely limited, particularly in the Japanese population.

[METHODS] This retrospective multicenter study enrolled 27 patients who were pathologically diagnosed with RET-NSCLC and started selpercatinib treatment between September 2021 and June 2024. Patients who had previously received other molecular-targeted drugs were excluded. Of the patients, 10 had received prior treatment and 17 had not.

[RESULTS] As of August 31, 2024, the median follow-up period was 12.0 months (range 0.5-31.5 months). The objective response rate (ORR) was 100% (8/8 cases) in the previously treated group and 81% (13/16 cases) in the treatment-naïve group. The median progression-free survival (PFS) was 13.3 months (95% confidence interval [CI] 0.5-not evaluable [NE]) in the previously treated group and 23.5 months (95% CI 5.7-NE) in the treatment-naïve group. The median overall survival was 25.4 months (95% CI 0.5-NE) in the previously treated group and not reached (95% CI NE-NE) in the treatment-naïve group. No significant differences were observed in any of these comparisons. The most frequent grade 3 adverse event (AE) was increased ALT (n = 11, 41%), followed by increased AST (n = 7, 26%).

[CONCLUSIONS] In Japanese patients treated with selpercatinib, efficacy in whole patients was similar to the worldwide population, whereas AEs (especially liver dysfunction) was more severe than worldwide population. This result highlights the need for careful dose management strategies for Japanese patients.