B2M and lung cancer: B2M, a component of MHC (major histocompatibility complex) Class‐I molecules, is important for antigen presentation in the adaptive immune system and is frequently the source of immunotherapy resistance.10 Recurrent inactivation of B2M has been discovered in lung cancer patient‐derived xenografts (PDX).41 The impaired HLA‐I complex by B2M could impair the response to anti‐PD‐1 therapy.