OBX1-012

Despite remarkable activity in epidermal growth factor receptor (EGFR)-mutant lung cancer patients, the clinical efficacy of EGFR tyrosine kinase inhibitors (TKIs) is limited by the emergence of acquired resistance, which is mostly caused by a secondary T790M mutation. Fortunately, newly developed, mutant-selective EGFR-TKIs against T790M have been proven as an effective therapeutic approach although only osimertinib has received the FDA approval until now.

To determine the in vitro and in vivo efficacy of a new EGFR TKI, OBX1-012 in cells with mutant EGFR.

Effects of OBX1-012 on cellular viability and EGFR-related signaling were determined in EGFR-mutant non-small cell lung cancer (NSCLC) cells, including cells harboring T790M mutations. In addition, in vivo efficacy of OBX1-012 was evaluated in xenograft models.

We report the discovery and preclinical assessment of another novel, mutant-selective EGFR-TKI, OBX1-012. Compared with other mutant-selective EGFR-TKIs such as olumitinib and osimertinib, it showed similar potency and selectivity for mutant EGFR. OBX1-012 treatment was highly effective against human EGFR-mutant lung cancer models with or without EGFR T790M, not only in vitro but also in vivo. However, OBX1-012 like other EGFR-TKIs failed to exhibit efficacy for the exon 20 insertion mutation or C797S mutation, which was generated by site-directed mutagenesis and stable transfection of Ba/F3 cells.

These results identify OBX1-012 as a highly effective, mutant-selective EGFR-TKI for the treatment of T790M-mediated resistance in NSCLC.