Programmed Cell Death 1 and Programmed Cell Death Ligands in Extranodal Natural Killer/T Cell Lymphoma: Expression Pattern and Potential Prognostic Relevance

The programmed cell death 1/programmed cell death ligands (PD-1/PD-Ls) axis is a potential immune escape mechanism of cancers. However, data on the PD-1/PD-Ls pathway in EBV-associated extranodal natural killer/T cell lymphoma (ENKTL) and its clinical implication are limited. Herein, we characterized PD-1/PD-L expression and its prognosis relevance in 49 ENKTL patients in Thailand. PD-L1 was expressed frequently on both lymphoma cells (61.2%) and stroma (77.5%), whereas PD-L2 expression was more common on lymphoma (63.2%) than stromal cells. PD-1 was positive in 20.5% of stroma, but undetectable on lymphoma cells. There was no association between baseline clinical characteristics and the expression PD-1/PD-Ls. The survival of patients with PD-Ls on tumor cells was poor. For PD-L1-positive versus negative cases, the 2-year event-free survival (EFS) was 42.2 versus 71.8% (p = 0.03) and 2-year overall survival (OS) was 45.4 versus 78.9% (p = 0.02), respectively. Comparing between patients with PD-L2-positive and PD-L2-negative lymphoma, the 2-year EFS was 37.1 versus 82.4% (p = 0.02) and 2-year OS was 45.2 versus 82.4% (p = 0.03), respectively. Neither PD-1 nor PD-Ls expression in the stroma predicted outcomes. In conclusion, PD-Ls were frequently expressed on ENKTL cells and associated with inferior outcomes. Therefore, PD-Ls are potential prognostic biomarkers and the roles of immune checkpoint blockade therapy in ENKTL deserve further investigation.

Variable frequencies of MALT lymphoma-associated genetic aberrations in MALT lymphomas of different sites

Although several recurrent genetic aberrations are known to occur in MALT lymphoma, no comprehensive study on the most prevalent MALT lymphoma-associated genetic aberrations is available. We therefore screened 252 primary MALT lymphomas for translocations t(11;18)(q21;q21), t(14;18)(q32;q21), and t(1;14)(p22;q32), and trisomies 3 and 18. The above-listed translocations occurred mutually exclusively and were detected overall in 13.5, 10.8, and 1.6% of the cases; trisomy 3 and/or 18 occurred in 42.1%. The frequency at which the translocations occurred varied markedly with the primary site of disease. The t(11;18)(q21;q21) was mainly detected in pulmonary and gastric tumors, whereas the t(14;18)(q32;q21) was most commonly found in lesions of the ocular adnexa/orbit, skin, and salivary glands. Trisomies 3 and 18 each occurred most frequently in intestinal and salivary gland MALT lymphomas. Our results demonstrate that the three translocations and trisomies 3 and 18 occur at markedly variable frequencies in MALT lymphoma of different sites.