Checkpoint CD47 expression in classical Hodgkin lymphoma

The glycoprotein CD47 regulates antiphagocytic activity via signal regulatory protein alpha (SIRPa). This study investigated CD47 expression on Hodgkin and Reed-Sternberg (HRS) cells in the classical Hodgkin lymphoma (cHL) tumour microenvironment and its correlation with prognosis, programmed-death (PD) immune markers, and SIRPa⁺ leukocytes. We conducted immunohistochemistry with CD47 and SIRPa antibodies on diagnostic biopsies (tissue microarrays) from cHL patients from two cohorts (n = 178). In cohort I (n = 136) patients with high expression of CD47 on HRS cells (n = 48) had a significantly inferior event-free survival [hazard ratio (HR) = 5.57; 95% confidence interval (CI), 2.78-11.20; p < 0.001] and overall survival (OS) (HR = 8.54; 95% CI, 3.19-22.90; p < 0.001) compared with patients with low expression (n = 88). The survival results remained statistically significant in multivariable Cox regression adjusted for known prognostic factors. In cohort II (n = 42) high HRS cell CD47 expression also carried shorter event-free survival (EFS) (HR = 5.96; 95% CI, 1.20-29.59; p = 0.029) and OS (HR = 5.61; 95% CI, 0.58-54.15; p = 0.136), although it did not retain statistical significance in the multivariable analysis. Further, high CD47 expression did not correlate with SIRPa⁺ leukocytes or PD-1, PD-L1 and PD-L2 expression. This study provides a deeper understanding of the role of CD47 in cHL during an era of emerging CD47 therapies.