Thus, it was unclear whether the D761Y mutation was “inherent” or “secondary” to gefitinib treatment.[12] Until 2020, Zhu et al reported the clinical efficacy of Icotinib and Osimertinib in a patient with metastatic NSCLC carryingan EGFR L858R/D761Y co-mutation. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.