Naquotinib mesylate (ASP8273 (mesylate)) is an orally available, mutant-selective and irreversible inhibitor of EGFR(iC50s of 8-33 nM and 230 nM for toward EGFR mutants and EGFR).

EGFR:230 nM

In NCI-H1650 (del ex19), Naquotinib inhibits cell growth with an IC50 value of 70nM while other EGFR-TKIs are only partially effective.Naquotinib selectively inhibits phosphorylation of EGFR and its down-stream signal pathway, ERK and Akt from 10nM in HCC827 and NCI-H1975 while inhibitory effects are only detected at 1000nM in A431[2].

In an NCI-H1975 xenograft model, complete regression of tumor is achieved after 14-days of Naquotinib treatment.?Complete regression is maintained in 50% of mice more than 85 days after cessation of Naquotinib treatment[2].