Expression Of Major Histocompatibility Complex (Mhc) Class Ii, But Not Mhc Class I, Predicts Outcome In Patients With Classical Hodgkin Lymphoma (Chl) Treated With Nivolumab (Programmed Death-1 [Pd-1] Blockade)

Background. Hodgkin Reed-Sternberg (HRS) cells evade antitumor immunity by multiple means, including copy gains of 9p24.1/ CD274(PD-L1) / PDCD1LG2 (PD-L2) and perturbed MHC class I and class II expression and associated antigen presentation. The identification of 9p24.1 alterations and PD-1 ligand overexpression in cHL prompted clinical evaluation of PD-1 blockade in this disease. In pilot and registration studies, response rates of ~70% were seen in patients (pts) with relapsed/refractory (R/R) cHL. However, the described deficits in HRS cell expression of MHC class I and II prompt speculation regarding the mechanism of action of PD-1 blockade in R/R cHL.