One method to establish Epstein-Barr virus-associated NK/T cell lymphoma mouse models

Brentuxinmab vedotin, alone or combine with bendamustine in the treatment of natural killer T cell lymphoma

Natural killer (NK)/T cell lymphoma is a highly aggressive subtype of non-Hodgkin lymphoma. The prognosis of patients with natural killer T cell lymphoma (NKTCL) remains poor. More potent treatment strategies are urgently needed to improve the survival of these patients with R/R NKTCL. CD30 expression has been reported to occur in about 40% of NK/T cell lymphoma. Brentuximab vedotin (BV), a monomethyl auristatin E conjugated CD30 antibody, targets CD30 to kill cancer cells. Therapeutic combination of BV and bendamustine has been shown to be highly effective in Hodgkin lymphoma. We investigated efficacy of BV in treating NKTCL as a single therapy, and in combination with bendamustine in vitro and in vivo. We determined CD30 expression levels in 6 NKTCL cell lines. The efficiency of lymphoma cell inhibition by BV correlates with CD30 expression. We also determined the efficacy of BV in combination with bendamustine and found synergistic effects with bendamustine in NKTCL. Combined BV and bendamustine treatment exerted synergistic antiproliferation effect and enhanced cell apoptotic in vitro and in vivo. Brentuximab vedotin and bendamustine synergistically arrested cell cycle at the G2/M phase in NKTCL cell lines. The combination of BV and bendamustine was demonstrated to synergistically damage DNA in NKTCL. This study provides a reference for possible application on using BV for the treatment of NKTCL, either as a single agent or in combination with bendamustine.

Selective drug combination vulnerabilities in STAT3- and TP53-mutant malignant NK cells

Mature natural killer (NK) cell neoplasms are rare but very aggressive types of cancers. With currently available treatments, they have a very poor prognosis and, as such, are an example of group of cancers in which the development of effective precision therapies is needed. Using both short- and long-term drug sensitivity testing, we explored novel ways to target NK-cell neoplasms by combining the clinically approved JAK inhibitor ruxolitinib with other targeted agents. We profiled 7 malignant NK-cell lines in drug sensitivity screens and identified that these exhibit differential drug sensitivities based on their genetic background. In short-term assays, various classes of drugs combined with ruxolitinib seemed highly potent. Strikingly, resistance to most of these combinations emerged rapidly when explored in long-term assays. However, 4 combinations were identified that selectively eradicated the cancer cells and did not allow for development of resistance: ruxolitinib combined with the mouse double-minute 2 homolog (MDM2) inhibitor idasanutlin in STAT3-mutant, TP53 wild-type cell lines; ruxolitinib combined with the farnesyltransferase inhibitor tipifarnib in TP53-mutant cell lines; and ruxolitinib combined with either the glucocorticoid dexamethasone or the myeloid cell leukemia-1 (MCL-1) inhibitor S63845 but both without a clear link to underlying genetic features. In conclusion, using a new drug sensitivity screening approach, we identified drug combinations that selectively target mature NK-cell neoplasms and do not allow for development of resistance, some of which can be applied in a genetically stratified manner.

Expression of PD-L1 on Monocytes Is a Novel Predictor of Prognosis in Natural Killer/T-Cell Lymphoma

Background: Natural killer/T-cell lymphoma (NKTCL) is a highly aggressive lymphoma with a dismal prognosis, and novel therapeutic targets are urgently needed. Programmed death-ligand 1 (PD-L1) has become a promising therapeutic target for various cancers, but most of the studies have focused on expression of PD-L1 on tumor cells. Expression of PD-L1 on tumor-infiltrating non-malignant cells, especially monocytes, has not been studied in NKTCL, and its prognostic value remains unknown. Materials and Methods: Expression of PD-L1 on tumor-infiltrating stromal cells was measured in NKTert and HS5 cells when cultured alone or co-cultured with NKTCL cell lines. Clinical samples were collected from 42 patients with newly diagnosed NKTCL. Expression of PD-L1 on monocytes was analyzed in patients' peripheral blood and tumor tissues using flow cytometry and immunofluorescent staining, respectively. Survival data were retrospectively collected and the prognostic significance of PD-L1 expression on monocytes was analyzed. Results: PD-L1 expression on tumor-infiltrating stromal cells was remarkably elevated when co-cultured with NKTCL cells. The percentage of PD-L1+ monocytes among all monocytes in peripheral blood was significantly higher in NKTCL patients than that in healthy individuals. Among NKTCL patients, percentage of PD-L1+ monocytes in blood positively correlated with that in tumor tissues. Patients with a higher percentage (≥78.2%) of PD-L1+ monocytes in blood or with a higher percentage (≥24.2%) of PD-L1+ monocytes in tumor tissues exhibited a significantly inferior survival, compared with their counterparts. A higher percentage of PD-L1+ monocytes in blood or tumor tissues was an independent adverse prognostic factor. Conclusions: Expression of PD-L1 on monocytes is up-regulated and has significant prognostic value in patients with NKTCL.

One method to establish Epstein-Barr virus-associated NK/T cell lymphoma mouse models

Novel nude mice model of human NK/T cell lymphoma were established by subcutaneously injecting two NK/T cell lymphoma cell lines into the right axillary region of mice and successful passages were completed by injecting cell suspension which was obtained through a 70‐μm cell strainer. These mice models and corresponding cell clones have been successfully developed for more than 8 generations. The survival rates of both resuscitation and transplantation in NKYS and YT models were 90% and 70% correspondingly. Pathologically, the tumour cells in all passages of the lymphoma‐bearing mice and cell lines obtained from tumours were parallel to initial cell lines. Immunologically, the tumour cells expressed the characteristics of the primary and essential NK/T lymphomas. The novel mice models maintained the essential features of human NK/T cell lymphoma, and they would be ideal tools in vivo for further research of human NK/T cell lymphoma.