Tukysa(tucatinib)

Tukysa (tucatinib) is a drug developed by Seattle Genetics, submitted as a New Drug Application (NDA 213411) with Priority status on December 20, 2019. It is available in 50mg or 150mg tablet formulations. The PDUFA goal date for this application was August 20, 2020.

Efficacy findings from the FDA review include an OS Hazard Ratio of 0.68 and a survival rate of 69%. The Progression-Free Survival (PFS) p-value was <.00001, and the median Duration of Response (DOR) per investigator was 6.9 months. The Clinical Benefit Rate (CBR) per BICR was 59.8% with a p-value of <0.00001. For patients with brain metastases, the stratified PFSBrainMets Hazard Ratio was 0.48, indicating a reduction in the risk of progression or death. In a combination regimen (Tucatinib + Trastuzumab + Capecitabine), the Objective Response Rate (ORR) ranged from 38.5% to 80.3%, with a median PFS per investigator of 7.8 months.

Safety data indicates that 71% of subjects in the tucatinib arm experienced a dose hold due to treatment-emergent adverse events (TEAEs), compared to 40.6% in the placebo arm. There were 8 subjects in the tucatinib arm who experienced TEAEs leading to death, versus 6 subjects in the control arm. Neutrophil count decreased (Grade 3-4) in 2.5% of patients on the tucatinib arm.