CDK4 and pneumonitis: The overall incidence of all-grade ILD/pneumonitis was 1.6% (131/8407) in the treatment group compared with 0.7% (50/7349) in the control group, thus suggesting that CDK4/6 inhibitors significantly increased the risk of all-grade ILD/pneumonitis; a higher incidence of grade 3 or higher ILD/pneumonitis was observed in the treatment group (21).