ERBB2 and non-small cell lung carcinoma: In the absence of standard-of-care therapies for HER2-mutant NSCLC with LMD, and the limited efficacy of currently available tyrosine kinase inhibitors in this molecular subtype, the decision was made to initiate systemic therapy with trastuzumab deruxtecan (Enhertu), a HER2-directed antibody-drug conjugate.