Medical Access Program for Patritumab Deruxtecan

Inclusion Criteria - Initial Requests * Signed informed consent. * Male or female aged ≥18 years (or local regulatory requirements). * Histologically or cytologically documented locally advanced or metastatic EGFRm NSCLC not amenable to curative surgery or radiation. * Documentation of radiological disease progression whilst on/after receiving most recent treatment regimen for locally advanced or metastatic disease. Patients must have received both of the following: 1. Prior treatment with any EGFR TKI, with at least one of them being osimertinib. Patients receiving an EGFR TKI at the time of signing informed consent should continue to take the EGFR TKI until 5 days prior to the first infusion of HER3 DXd. 2. Systemic therapy with at least 1 PBC regimen. * Documentation of an EGFR-activating mutation detected from tumor tissue or blood (exon 19 deletion or L858R mutation). * Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 or 1 at the time of entering the Medical Access Program. * Adequate levels of bone marrow reserve and organ function, based on local laboratory data, within 14 days prior to the first HER3-DXd infusion as specified in the MAP protocol. * Female patients of childbearing potential must have a negative urine or serum pregnancy test at the time of entering the Medical Access Program and must be willing to use highly effective contraception during the treatment period and for at least 7 months following the last dose of HER3-DXd. Additionally, female patients must agree to not donate, or retrieve for their own use, eggs from the time of entering the Medical Access Program and throughout the treatment period, and for at least 7 months after the final HER3-DXd administration. Male patients with female partners who are able to become pregnant must be willing to use a highly effective form of contraception or avoid intercourse during the treatment period and for at least 4 months following the last dose of HER3- DXd. Additionally, male patients must agree not freeze or donate sperm from time of entering the Medical Access Program and throughout the treatment period, and for at least 4 months after final dose of HER3- DXd. * Life expectancy of \>3 months as determined by the treating physician. Inclusion Criteria - Resupply Requests * Treating physician must confirm that the patient is deriving continued benefit from treatment. * Treating physician must confirm that all required safety information has been reported as per local laws/regulations. Exclusion Criteria - Initial Requests * Patient is currently participating in or is in follow up for any Daiichi Sankyo ADC clinical trial including the HERTHENA-Lung02 'Trial of Patritumab Deruxtecan Initiated in Patients with EGFR-Mutated Metastatic Non-Small Cell Lung Cancer' (NCT05338970). * Patient has previous or current histologic or cytologic evidence of small cell OR combined small cell/non-small cell disease in the archival tumor tissue or pre treatment tumor biopsy. * Patient has any history of (non-infectious) ILD/pneumonitis that required steroids, has current ILD/pneumonitis, or where suspected ILD/pneumonitis cannot be ruled out by imaging at the time of entering the Medical Access Program. * Patient has clinically severe respiratory compromise (based on treating physician's assessment) resulting from intercurrent pulmonary illnesses including, but not limited to: a) any underlying pulmonary disorder, b) any autoimmune, connective tissue or inflammatory disorders, OR c) prior complete pneumonectomy. * Inadequate washout period prior to the first HER3-DXd infusion as specified in protocol. * Clinically significant unresolved toxicities from previous anticancer therapy, defined as toxicities (other than alopecia) not yet resolved to National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE v5.0) Grade ≤1 or baseline. Patients with chronic Grade 2 toxicities may be eligible at the discretion of the treating physician after consultation with the designated Sponsor Medical Reviewer. * Patient has clinically significant and/or uncontrolled cardiovascular disease prior to the first HER3-DXd infusion. * Active hepatitis B virus (HBV) and/or hepatitis C virus infection, such as those with serologic evidence of viral infection within 28 days of the first HER3-DXd infusion. * Human immunodeficiency virus (HIV) infection that is not well controlled as specified in the protocol. * History of hypersensitivity to either the drug substance or any excipients in HER3-DXd. * Female patient who is pregnant, breast-feeding, or intending to become pregnant. * Prior or ongoing clinically relevant illness, medical condition, surgical history, physical finding, or laboratory abnormality that, in the treating physician's opinion, could affect the safety of the patient. * Clinically significant corneal disease. * Evidence of ongoing uncontrolled systemic bacterial, fungal, or viral infection. Note: Patients with localized fungal infections of skin or nails are eligible.