This study aimed to assess the efficacy and safety of treatment with avelumab, an anti-programmed death ligand 1 (PD-L1) antibody, in patients with relapsed or refractory extranodal natural killer (NK)/T-cell lymphoma (ENKTL). In this phase II trial, 21 patients with relapsed or refractory ENKTL were treated with 10 mg/kg of avelumab on days 1 and 15 of a 28-day cycle (ClinicalTrials.gov Identifier: NCT03439501). The primary end point was the complete response (CR) rate based on the best response. Targeted sequencing and immunohistochemistry were performed using pretreatment tumor tissue, and blood samples were drawn pre- and post-treatment for measurement of cytokines and soluble programmed cell death protein 1 (PD1), PD-L1, and PD-L2. The CR rate was 24% (5/21) and the overall response rate was 38% (8/21). Although nonresponders showed early progression, five responders currently continue to receive treatment and have maintained their response. Most treatment-related adverse events were grade 1 or 2; no grade 4 adverse events were observed. Treatment responses did not correlate with mutation profiles, tumor mutation burden, serum levels of cytokines, or soluble PD1/PD-L1 and PD-L2. However, the response to avelumab was significantly associated with the expression of PD-L1 by tumor tissue (P = 0.001). Therefore, all patients achieving CR showed high PD-L1 expression, and their tumor subtyping based on PD-L1 expression correlated with treatment response. In conclusion, avelumab showed single-agent activity in a subset of patients with relapsed or refractory ENKTL. The assessment of PD-L1 expression on tumor cells might be helpful for identifying responders to avelumab.

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Background The programmed cell death protein 1 (PD‐1) and its ligand 1 and 2 (PD‐L1/PD‐L2) regulate the immune system, and the checkpoint pathway can be exploited by malignant cells to evade anti‐tumor immune response. Soluble forms (sPD‐1/sPD‐L1/sPD‐L2) exist in the peripheral blood, but their biological and clinical significance is unclear. Method Time‐resolved immunofluorometric assay (TRIFMA) and enzyme‐linked immunosorbent assay (ELISA) were used to measure sPD‐1, sPD‐L1, and sPD‐L2 levels in serum from 131 lymphoma patients and 22 healthy individuals. Results Patients had higher sPD‐1 and sPD‐L2 levels than healthy individuals. In diffuse large B‐cell lymphoma, patients with high International Prognostic Index score had higher sPD‐1 levels and sPD‐L2 levels correlated with subtype according to cell of origin. Compared to other lymphoma types, follicular lymphoma displayed higher sPD‐1 and lower sPD‐L1 levels along with lower ligand/receptor ratios. Conclusion This is the first study to simultaneously characterize pretherapeutic sPD‐1, sPD‐L1, and sPD‐L2 in a variety of lymphoma subtypes. The relation between higher sPD‐1 levels and adverse prognostic factors suggests a possible biological role and potential clinical usefulness of sPD‐1. Moreover, the reverse expression pattern in follicular lymphoma and T‐cell lymphoma/leukemia may reflect biological information relevant for immunotherapy targeting the PD‐1 pathway.

Histological transformation (HT) remains the leading cause of mortality in follicular lymphoma (FL), underlining the need to identify reliable transformation predictors. The hyaluronic acid receptors CD44 and the receptor for hyaluronan mediated motility (RHAMM, also known as HMMR and CD168), have been shown to be involved in the pathogeneses of both solid tumors and hematological malignancies. In an attempt to improve risk stratification, expression of RHAMM and CD44 were evaluated by immunohistochemistry and digital image analysis in pre-therapeutic tumor-tissue biopsies from FL patients, either without (nt-FL, n = 34), or with (st-FL, n = 31) subsequent transformation, and in paired biopsies from the transformed lymphomas (tFL, n = 31). At the time of initial diagnosis, samples from st-FL patients had a higher expression of RHAMM compared with samples from nt-FL patients (p < 0.001). RHAMM expression further increased in tFL samples following transformation (p < 0.001). Evaluation of CD44 expression showed no differences in expression comparing nt-FL, st-FL, and tFL samples. Shorter transformation-free survival was associated with high tumoral and intrafollicular RHAMM expression, as well as with low intrafollicular CD44 expression (p = 0.002, p < 0.001, and p = 0.034, respectively). Our data suggest that high tumor-tissue RHAMM expression predicts the risk of shorter transformation-free survival in FL patients already at initial diagnosis.