Real-world incidence of and risk factors for abemaciclib-induced interstitial lung disease in Japan: a nested case-control study of abemaciclib-induced interstitial lung disease (NOSIDE)

Purpose: The exact incidence of and risk factors for interstitial lung disease (ILD), a serious side effect of abemaciclib, remain unknown in real-world settings. We examined the incidence of and risk factors for abemaciclib-induced ILD in patients with advanced breast cancer (ABC) in Japan.

Patients and methods: Retrospective clinical information was collected from charts of patients with ABC who had started abemaciclib treatment at 77 participating institutions between November 30, 2018 and December 31, 2019. The clinical information of patients who developed ILD (including suspected cases) were reviewed by an independent committee of extramural experts to adjudicate abemaciclib-induced ILD. We performed a nested case-control study for efficient identification of ILD risk factors and conducted multivariate Cox regression analysis to identify independent predictors of ILD.

Results: Among patients taking abemaciclib, the incidence of abemaciclib-induced ILD was 5.0% (n = 59/1189), and the mortality rate was 0.7% (n = 8). The timing of ILD onset varied but occurred most frequently within 180 days of beginning abemaciclib treatment (64.4%). The incidence of abemaciclib-induced ILD was significantly associated with Eastern Cooperative Oncology Group performance status (ECOG PS) ≥ 2 [hazard ratio (HR) 5.03; 95% confidence interval (CI) 2.26-11.11] or a past medical history of interstitial pneumonia (IP) (HR 6.49; 95% CI 3.09-13.70).

Conclusions: In this study, we have for the first time determined the real-world incidence of and risk factors for abemaciclib-induced ILD in Japan. Although abemaciclib-induced ILD is serious in real-world settings, careful patient selection and close monitoring of those with poor ECOG PS and/or a history of IP may minimize ILD risk. This study was registered on the UMIN registry (Date: May 11, 2020/ ID: UMIN000040357).