We know that, AP26113 (see structure) is a highly potent ALK inhibitor with IC50 of 0.62 nM. As an ALK inhibitor, AP26113 overcomes mutation-based resistance in NSCLC models. Multiple mutations in ALK were identified that conferred resistance to crizotinib, but not AP26113, including the L1196M "gatekeeper" mutation which has now been observed clinically in patients who initially responded to crizotinib and then relapsed. AP26113 also inhibits activated EGFR in preclinical models, including the T790M "gatekeeper" mutant that confers resistance to current EGFR inhibitors. Constitutive EGFR activity due to activating mutation is a key feature of certain non-small cell lung cancers, and the T790M mutation causes resistance to inhibitor therapy in approximately 50 percent of these cases. In preclinical studies, AP26113 was shown to be specific for mutated EGFR and avoids inhibition of native (endogenous or unmutated) EGFR; such inhibition is thought to be associated with the toxicity of other EGFR inhibitors.
