EGFR and non-small cell lung carcinoma: Additionally, in cell-based assays, addition of DS-1205b (a sulfate trihydrate of DS-1205a, which is the free form of DS-1205c) with erlotinib or osimertinib prolonged the therapeutic benefit of the EGFR TKIs by inhibiting signaling downstream of EGFR; it also inhibited acquired resistance to osimertinib and erlotinib in an EGFR-mutant (exon 19 deletion) NSCLC xenograft mouse model [16].