Merck kicks off its first TROP2 phase 3

Just over a year since Merck & Co. acquired ex-China rights to Kelun Biotech's anti-TROP2 ADC sacituzumab tirumotecan for $47m up front, the first Merck-sponsored phase 3 trial (MK-2870-004) is getting started. The study will evaluate sacituzumab tirumotecan versus chemotherapy in pre-treated non-squamous NSCLC. Although it allows patients with different genomic alterations, the main focus will be among those with EGFR mutations (exon 19del or exon 21 L858R) as it is here where the dual primary endpoints of PFS and OS will be evaluated. While this is Merck's first phase 3 trial for the asset, Kelun is already advancing through a rapidly growing phase 3 programme in China. Its successful phase 3 in triple-negative breast cancer could lead to the first approval in the third-line plus setting next year. A second trial, very similar to Merck's, is under way in EGFR-TKI pretreated EGFR-mutant NSCLC, a setting where the NMPA granted the TROP2 asset breakthrough therapy designation. Additionally, a phase 3 trial in ER+/HER2- breast cancer patients who failed at least first-line chemotherapy is in progress, according to the Chinese trial registry.