While there is a suggestion that the combination of abemaciclib and pembrolizumab has antitumor activity in patients with HR+, HER2− MBC, there were higher rates of grade ≥3 transaminase elevations and ILD/pneumonitis, SAEs and treatment discontinuation due to AEs observed with abemaciclib plus pembrolizumab with/without anastrozole compared to previous reports. The gene discussed is ERBB2; the disease is pneumonitis.