Net antitumoral immunity and the predictive power of conventional prognosticators in diffuse large B-cell lymphoma.

8542 Background: Immunity represents a balance between immune-effectors and immune-checkpoints. In DLBCL, circulating lymphocyte:monocyte ratios are prognostic, implicating them as surrogate immune-effectors and immune-checkpoints within the tumor microenvironment (TME). Detailed assessment of blood would enable identification of the optimal TME immune-effector and monocyte/macrophage-checkpoints to assist sub-stratification of conventional prognosticators. Methods: Blood from 140 R-CHOP treated DLBCL patients in the NHL21 Australasian Leukaemia and Lymphoma Group trial were analysed. A circulating immune-effector:monocyte-checkpoint signature segregating interim-PET/CT positivity was identified. Intratumoral applicability was tested in two independent R-CHOP treated DLBCL cohorts, with cell-of-origin (COO) and international prognostic index (IPI) as co-variates. Results: Patient monocytes suppressed T-cell proliferation and NK-cell rituximab-ADCC. Both CD14+HLA-DRlo monocytoid-myeloid derived suppressor ...