CTLA4 and cancer: CTLA4 and PD1 are highly expressed by various types of cancers, and their binding to their respective ligands contribute to T cell functional impairment, which fails to elicit the required immunity against minimal residual disease, and thereby play an important role in cancer recurrence.459 The discovery of immune-checkpoint’s role in cancer has changed the paradigm of cancer therapeutics and added immunotherapy to the list of common three cancer pillars including surgery, targeted therapy, radiotherapy, and chemotherapy.