Immune checkpoint blockade (ICB) has revolutionized the prognosis of several advanced-stage solid tumors. However, its success has been far more limited in hematological malignancies and is mostly restricted to classical Hodgkin lymphoma (cHL) and primary mediastinal B cell lymphoma (PMBCL). In patients with non-Hodgkin lymphoma (NHL), response to PD-1/PD-L1 ICB monotherapy has been relatively limited, although some subtypes are more sensitive than others. Numerous predictive biomarkers have been investigated in solid malignancies, such as PD-L1 expression, tumor mutational burden (TMB) and microsatellite instability (MSI), among others. This review aims to appraise the current knowledge on PD-1/PD-L1 ICB efficacy in lymphoma when used either as monotherapy or combined with other agents, and describes potential biomarkers of response in this specific setting.

R-CHOP immuno-chemotherapy significantly improved clinical management of diffuse large B-cell lymphoma (DLBCL). However, 30–40% of DLBCL patients still present a refractory disease or relapse. Most of the prognostic markers identified to date fail to accurately stratify high-risk DLBCL patients. We have previously shown that the nuclear protein CYCLON is associated with DLBCL disease progression and resistance to anti-CD20 immunotherapy in preclinical models. We also recently reported that it also represents a potent predictor of refractory disease and relapse in a retrospective DLBCL cohort. However, only sparse data are available to predict the potential biological role of CYCLON and how it might exert its adverse effects on lymphoma cells. Here, we characterized the protein interaction network of CYCLON, connecting this protein to the nucleolus, RNA processing, MYC signaling and cell cycle progression. Among this network, NPM1, a nucleolar multi-functional protein frequently deregulated in cancer, emerged as another potential target related to treatment resistance in DLBCL. Immunohistochemistry evaluation of CYCLON and NPM1 revealed that their co-expression is strongly related to inferior prognosis in DLBCL. More specifically, alternative sub-cellular localizations of the proteins (extra-nucleolar CYCLON and pan-cellular NPM1) represent independent predictive factors specifically associated to R-CHOP refractory DLBCL patients, which could allow them to be orientated towards risk-adapted or novel targeted therapies.

Background: Post‐transplant lymphoproliferative disorders (PTLD) may significantly impair outcomes in children after solid organ transplantation (SOT). Diagnosis and treatment may be challenging. We analyze a representative pediatric liver transplant (LT) cohort in light of these challenges.Methods: Pediatric LT recipients monitored by the Swiss Pediatric Liver Center from 2009 to 2021 with a suspicion of Epstein–Barr virus (EBV) driven PTLD were included. All cases were retrospectively reviewed using the World Health Organization (WHO) 2022 classification criteria for Pediatric Tumors. Two groups were defined: (1) histologically confirmed PTLD, and (2) ‘indeterminate PTLD’ if criteria were not entirely met.Results: During the inclusion period, 111 patients underwent LT. Histology review confirmed PTLD in 13 patients (11.7%) while 3 patients were included in the ‘indeterminate’ group. The most common subtype was non‐destructive PTLD (6/13), followed by monomorphic (4/13) and polymorphic PTLD (3/13). Hypermetabolism on whole body (¹⁸F) fluorodeoxyglucose PET/CT helped define adequate biopsy location in 11/13 patients. Three patients with monomorphic PTLD also showed low‐grade PTLD subtypes in other biopsy sites. Nine patients received mTOR inhibitors after diagnosis, either as monotherapy or in combination with calcineurin inhibitors, without major side effects.Conclusions: The detailed analysis of our series of pediatric LT patients with PTLD allowed for the development of a diagnostic and management algorithm, now applied at our institution. Spatial and temporal heterogeneity argues in favor of multiple and, if necessary, repeated biopsies at different sites.

Immune checkpoint blockade (ICB) has revolutionized the prognosis of several advanced-stage solid tumors. However, its success has been far more limited in hematological malignancies and is mostly restricted to classical Hodgkin lymphoma (cHL) and primary mediastinal B cell lymphoma (PMBCL). In patients with non-Hodgkin lymphoma (NHL), response to PD-1/PD-L1 ICB monotherapy has been relatively limited, although some subtypes are more sensitive than others. Numerous predictive biomarkers have been investigated in solid malignancies, such as PD-L1 expression, tumor mutational burden (TMB) and microsatellite instability (MSI), among others. This case-illustrated review aims to appraise the current knowledge on PD-1/PD-L1 ICB efficacy in lymphoid malignancies, when used either as monotherapy or combined with other agents, and describes potential biomarkers of response in this specific setting.