Osimertinib-13C,d3 is a deuterated form of Osimertinib labeled with 13C. Osimertinib (AZD9291) is an orally active, covalent, irreversible EGFR inhibitor with mutation selectivity, effectively inhibiting L858R (IC50=12 nM) and L858R/T790M (IC50=1 nM) EGFR mutations. It addresses resistance to EGFR inhibitors caused by the T790M mutation in lung cancer.