Joseph G. Taylor, Andrew Clear, Maria Calaminici, John G. Gribben. Programmed cell death protein-1 (PD1) expression in the microenvironment of classical Hodgkin lymphoma is similar between favorable and adverse outcome and does not enrich over serial relapses with conventional chemotherapy. Haematologica 2018;104(1):e42-e44; https://doi.org/10.3324/haematol.2018.204818.