Reading Duration of Response Across ROS1 Inhibitor Trials

Martin Dietrich, MD, PhD, says duration of response and progression-free survival converge in the untreated setting, because response rates approach the whole population, so the two numbers carry much the same information. In the pretreated setting they diverge: Dietrich puts the chance of response at roughly even, and says a durable response suggests the resistance mechanism was one the second agent could reach, while no response should prompt a change of approach rather than another inhibitor of the same class. Wade Iams, MD, says the first scan tells him a great deal, since responses on a tyrosine kinase inhibitor come quickly, and within about two months he can usually estimate durability. Ticiana Leal, MD, adds that resistance mutations including G2032R still need study, and that tissue biopsy may be required.