CH5424802

CH5424802 is a potent and selective ALK inhibitor with an IC50 of 1.9 nM.[1] The dissociation constant (KD) value of CH5424802 for ALK in an ATP-competitive manner is 2.4 nM. CH5424802 has substantial inhibitory potency against both native ALK and L1196M with Ki of 0.83 and 1.56 nM, respectively. ^[1] CH5424802 displays high target selectivity and the stronger anti-proliferative activity against KARPAS-299. CH5424802 inhibits KAPRAS-299 with an IC50 of 3 nM, and KDR with an IC50 of 1.4 μM. The metabolic stability of CH5424802 is very high. ^[2] The inhibitory activity of CH5424802 for two hot spot-activating mutations in neuroblastoma, F1174L and R1275Q, is comparable to that for wild-type ALK. CH5424802 shows weak or no inhibition against 24 protein kinases other than ALK including ABL, EGFR, FGFR2, HER2 KIT et al. Only three kinases, ALK, GAK, and LTK, shows more than 50% prevention at 10 nM, which corresponds to approximately 5-fold higher concentration of IC50 values for ALK. LTK is known to show greatest sequence similarity to ALK. CH5424802 prevents autophosphorylation of ALK in NCI-H2228 NSCLC cells expressing EML4-ALK. CH5424802 also suppresses the phosphorylation of STAT3 and AKT, but not of ERK1/2. CH5424802 completely inhibits the phosphorylation of STAT3 at Tyr705.[1] CH5424802 is preferentially efficacious against NCI-H2228 cells expressing EML4-ALK, but not ALK fusion-negative NSCLC cell lines, including HCC827 cells (EGFR exon 19 deletion), A549 cells (KRAS mutant), or NCI-H522 cells (EGFR wild-type, KRAS wild-type, and ALK wild-type) in monolayer culture. CH5424802 elicits an apoptotic marker—caspase-3/7-like activation—in NCI-H2228 spheroid cells. CH5424802 blocks the growth of two lymphoma lines, KARPAS-299 and SR, with NPM-ALK fusion protein but does not influence the growth of an HDLM-2 lymphoma line without ALK fusion. ^[1] Oral administration of CH5424802 dose-dependently inhibits tumor growth with an ED50 of 0.46 mg/kg and tumor regression. Treatment of 20 mg/kg CH5424802 reveals rapid tumor regression by 168%, the tumor volume in any mouse is <30 mm3 after 11 days of treatment (at day 28), a potent antitumor effect is maintained, and tumor regrowth does not occur throughout the 4-week drug-free period. The half-life and the oral bioavailability of CH5424802 in mice are 8.6 hours and 70.8%, respectively. At a repeated dose of 6 mg/kg, the mean plasma levels reached 1.7, 1.5, and 0.3 nM at 2, 7, and 24 hours post-dose, respectively. At any dose level, no differences in body weight or gross signs of toxicity are observed between control- and CH5424802-treated mice. In contrast, CH5424802 has practically no antitumor effect in the xenograft model of A549, an NSCLC cell line that does not express ALK fusions. Administration of CH5424802 leads to tumor growth prevention and tumor regression. Tumor growth inhibition at 20 mg/kg is 119% for KARPAS-299 and 104% for NB-1 on day 20. CH5424802 inhibits the phosphorylation of STAT3 in a dose-dependent manner (2–20 mg/kg). A partial decrease in AKT phosphorylation was also observed in CH5424802-treated xenograft tumors. ^[1]