Clinical Impact of Pre-Existing Autoantibodies in Patients With SCLC Treated With Immune Checkpoint Inhibitor: A Multicenter Prospective Observational Study

Introduction

Although pretreatment autoantibodies have been associated with immune-related adverse events (irAEs) and immune checkpoint inhibitor treatment efficacy in some types of cancer, their importance has not been evaluated in patients with SCLC.

Methods

A multicenter prospective observational study was conducted on a total of 52 patients with extensive-disease SCLC who received immune checkpoint inhibitors in combination with chemotherapy as the first-line treatment at either of the six participating centers in Japan. Pretreatment serum samples were collected and analyzed for autoantibodies (rheumatoid factor, antinuclear antibodies, and antithyroid). Moreover, 12 antineuronal antibodies (AMPH, CV2, PNMA2, Ri, Yo, Hu, Recoverin, SOX1, Titin, Zic4, GAD65, and Tr) were analyzed using immunoblot assays. The primary end point was the incidence of irAEs with or without autoantibodies. The secondary end points were progression-free survival (PFS) and overall survival (OS) on the basis of the presence or absence of autoantibodies.

Results

PFS and OS were 4.4 and 25.3 months, respectively. Autoantibodies (rheumatoid factor, antinuclear antibodies, and antithyroid antibodies) were detected in 29 patients (56%). In total, irAEs were observed in 18 patients (35%); irAE incidence was 48% in the autoantibody-positive group and 17% in the autoantibody-negative group (p = 0.039). There was no difference in PFS or OS between patients with and without autoantibodies (4.4 mo versus 4.6 mo, p = 0.36; 15.3 mo versus 18.2 mo, p = 0.36). Antineuronal antibodies were detected in 16 patients (31%). However, the development of neurologic irAEs was not observed in both groups.

Conclusions

Vigilance is required against the development of irAEs in pretreatment antibody-positive patients.