Inclusion Criteria:  Age >= 18 years Histological confirmation of pleural mesothelioma Measurable disease Eastern Cooperative Oncology Group (ECOG) performance status (PS) =< 2  Negative pregnancy test done =< 14 days prior to registration, for women of childbearing potential only. NOTE: male/female: Must be willing to use birth control for the entire study and must agree to use one of the following birth control methods listed:  Hormonal methods, such as birth control pills, patches, injections, vaginal ring, or implants Barrier methods (such as a condom or diaphragm) used with a spermicide (a foam, cream, or gel that kills sperm) Intrauterine device (IUD) Abstinence (no sex) Provide written informed consent Willing to return to enrolling institution for follow-up (during the active monitoring phase of the study) Willing to provide blood samples for correlative research purposes Patient has received or is planning to receive ICI for mesothelioma Patient is planning to receive SBRT (stereotactic body radiation therapy) for mesothelioma  Exclusion Criteria:  Any of the following:  Pregnant women Nursing women