Ripretinib's Role in Fourth-Line Treatment of GIST

Dr. Pollack characterizes ripretinib as an outstanding fourth-line agent that filled a critical unmet need in post-third-TKI progression settings. Before ripretinib's availability, patients lacked effective treatment options after exhausting the first three lines of therapy.

The INVICTUS trial demonstrated remarkable efficacy with significant overall survival improvement (15 versus 6 months) and progression-free survival benefit (6 months versus 1 month) compared to placebo. The 85% reduction in progression or death risk (HR 0.15) represents unprecedented magnitude in this treatment-refractory population.

Ripretinib's excellent tolerability profile supports durability of treatment, with grade 3/4 treatment-related adverse events being uncommon (lipase increase 5%, hypertension 4%, fatigue 2%) and low discontinuation rates enabling patients to remain on therapy for extended periods.

The drug's unique switch-control mechanism differentiates it from predecessor agents by binding both the switch pocket and activation loop, providing coverage against primary and secondary KIT/PDGFRA mutations. This includes activation-loop mutations (exons 17/18) that typically require type I inhibitor activity.

Post-progression dose escalation from 150mg daily to 150mg twice daily showed extended median progression-free survival by 3.7 months in the INVICTUS IPDE sub-study, providing additional treatment option without requiring new agents. Despite doubling the dose, tolerability remained manageable for most patients already established on monotherapy dosing.