Efficacy of second line and subsequent treatments of small cell lung cancer with and without immune checkpoint inhibitor combination therapy

Abstract

Background

Immune checkpoint inhibitors (ICIs) combined with platinum-doublet chemotherapy (ICI-chemo) have become the standard of care for extensive-stage small cell lung cancer (ES-SCLC). However, the effect of ICI-chemo on the efficacy of subsequent chemotherapy remains unknown. This study aimed to investigate the efficacy of second and subsequent treatments of SCLC with and without ICI combination therapy.

Methods

We performed an analysis of patients with ES-SCLC between January 2015 and June 2023. The ICI-chemo groups were defined as patients who received ICI-chemo as first-line therapy between September 2019 and June 2023, after ICI-chemo was reimbursed in Japan. The non–ICI–chemo groups were defined as patients who received platinum-doublet therapy between January 2015 and August 2019 and were considered eligible for ICI-chemo.

Results

In total, 224 patients were included (91 and 133 patients who received ICI-chemo and non–ICI–chemo, respectively). There were no significant differences in patient characteristics between the groups. There was no significant difference in progression-free survival (PFS) and overall survival (OS) for first-line treatment between the two groups. The median PFS and OS periods for second-line treatment were 3.9 and 3.9 months and 10.3 and 10.7 months in the ICI-chemo and non–ICI–chemo groups, respectively, without significant difference. Most patients in both groups received amrubicin as the second-line treatment. Moreover, the PFS and OS periods for third-line treatment were not significantly different between the ICI-chemo and non–ICI–chemo groups.

Conclusions

In ES-SCLC, there is no significant additive effect on PFS and OS of second- and subsequent line treatments following ICI-chemo at first-line treatment.