PDL1 shapes the classical Hodgkin lymphoma microenvironment without inducing T-cell exhaustion.

Classical Hodgkin lymphoma (CHL) is unusually sensitive to PD1 inhibition and PDL1 is highly expressed on CHL cells and in the tumor microenvironment. This could be interpreted as evidence of exhaustion, but paradoxically, PD1+ lymphocyte infiltration does not predict response to PD1 inhibitors and no increase in cytotoxic markers is seen after PD1 therapy as might be expected with reversal of exhaustion. In contrast to PD1, elevated PDL1 does predict response to PD1 inhibitors and recent data associate both retained CHL MHC-II expression and increased T helper (TH) T-cell receptor diversity with response, suggesting a connection to the TH compartment. We performed a phenotypic, spatial and functional assessment of T-cell exhaustion in CHL and found co-expression of an exhaustion marker and lower PD1 expression in CHL than in reactive nodes whereas the proliferative and cytokine production capacity were similar in CHL and the reactive nodes. We found no correlation between PDL1 expression and exhaustion signatures. Instead, we identified a strong association between PDL1 expression and CHL MHC-II expression, TH recruitment, and enrichment of TH1 regulatory cells. These data suggest that a dominant effect of PDL1 expression in CHL may be TH engagement and promotion of a regulatory microenvironment rather than maintenance of exhaustion.

Carmustine, etoposide, cytarabine, and melphalan (BEAM)-campath allogeneic stem cell transplantation for aggressive non-hodgkin lymphoma: an analysis of outcomes from the British Society of Blood and Marrow Transplantation.

The role of allogeneic stem cell transplantation (SCT) in the management of aggressive non-Hodgkin lymphoma (NHL) remains to be defined, but the number of procedures performed continues to increase. We report here the outcomes of allogeneic SCT using carmustine, etoposide, cytarabine, and melphalan (BEAM)-Campath (Genzyme Corporation, Cambridge, MA) conditioning for aggressive NHL as reported to the British Society of Blood and Marrow Transplantation (BSBMT). This retrospective study identified 46 patients who reported to the BSBMT registry as having undergone BEAM-Campath conditioned allogeneic SCT for aggressive NHL between 1999 and 2010. Disease histology was diffuse large B cell lymphoma (DLBCL, n = 25), DLBCL/Burkitt lymphoma (n = 5), and T cell lymphoma (n = 16). At diagnosis, the median age was 42.5 (range, 17 to 59), 37 had advanced stage disease (Ann Arbor III/IV), 28 had 2 or more extra-nodal sites of disease, and 23 had elevated lactate dehydrogenase. International prognostic index was high or high/intermediate in 58%. The median number of prior therapies was 3 (range, 1 to 5) and 5 patients had previously undergone transplantation (4 autologous, 1 allogeneic). The median age at transplantation was 44.8 (range, 18 to 59), with 34 patients demonstrating chemo-sensitive disease and 22 undergoing transplantation in first response. Performance score was good in 40 patients and all engrafted with a median of 14 days (range, 11 to 27) to neutrophil recovery. At latest follow-up, 20 patients were alive with 17 in complete remission. Acute graft-versus-host disease (GVHD) developed in 7 patients and chronic GVHD developed in 13 (7 limited, 6 extensive). Five patients died from nonrelapse causes, with a cumulative incidence of nonrelapse mortality of 7% at 100 days and 11% at 3 and 5 years. Twenty-one patients died after lymphoma relapse, with a cumulative incidence of relapse/progression of 51% at 1 year and 53% at 5 years. Disease status at transplantation had no impact on relapse rate. Progression-free survival was 41% at 1 year and 36% at 5 years. Overall survival was 54% at 1 year and 42% at 5 years. Overall, BEAM-Campath-conditioned allogeneic SCT is well tolerated and able to deliver durable disease-free survival to a subset of patients with aggressive NHL. However, the high relapse rates indicate further investigation is needed to identify those patients most likely to benefit.