Tumor antigens presented by MHC molecules on the cell surface can be recognized by T cells. Identification of these antigens—a field known as immunopeptidomics—has revolutionized the development of cancer immunotherapies. For optimal efficacy, these immunotherapies need to target the specific genomic vulnerabilities of each patient’s tumor. However, the amount of required starting material (> 50 million cells) utilized by traditional gold-standard methods is not applicable to fine needle-aspirated