Imlunestrant

Imlunestrant is a drug under regulatory review, with a marketing authorization application submitted on 20 November 2024. A CHMP positive opinion was issued on 13 November 2025, and the drug received New Active Substance (NAS) status on the same date. The recommended dose for imlunestrant is 400 mg QD. The drug demonstrated efficacy in a phase 3 pivotal study involving 331 patients, where it achieved a median Progression-Free Survival (PFS) of 5.49 months compared to 3.84 months in the standard of care (SOC) arm, with a PFS Hazard Ratio of 0.617 (p-value 0.0008). Median Overall Survival (OS) was 34.50 months for imlunestrant versus 23.1 months for the SOC arm, with an OS Hazard Ratio of 0.603 (p-value 0.0043).

Safety data indicated that 82.6% of patients experienced any treatment-emergent adverse events (TEAEs), with 17.1% experiencing Grade ≥3 TEAEs. Serious adverse events (SAEs) were reported in 16.8% of patients receiving imlunestrant plus abemaciclib, compared to 11.7% in the SOC arm. Deaths in the imlunestrant arm were 19.0%. Notable Grade ≥3 adverse events included nausea (0.3%) and increased transaminases (1.2%) for imlunestrant, compared to 13.0% and 14.8% respectively for the SOC arm for any grade.