Targeted therapy for EBV-associated B-cell neoplasms

Epstein-Barr virus (EBV) is directly implicated in several B-cell lymphoid malignancies. EBV-associated lymphomas are characterized by prominent activation of the NF-kB pathway and targeting this pathway establishes a rationale for a therapeutic approach. The ubiquitin/proteasome signaling plays an essential role in the regulation of the NF-kB pathway. Ixazomib is an FDAapproved, orally bioavailable proteasome inhibitor. Here we report the first preclinical evaluation of ixazomibmediated growth-inhibitory effects on EBV-infected B-lymphoblastoid cell lines Raji and Daudi. Ixazomib induced apoptosis in these cell lines in a dosedependent manner. Cell-cycle analysis demonstrated ixazomib treatment induced cell-cycle arrest at the G2-M phase with a concomitant decrease in G0-G1 and S phases. The results further revealed an increase in p53, p21, and p27 levels and a decrease in survivin and c-Myc protein levels. Mechanistically, ixazomib treatment resulted in the accumulation of polyubiquitinated proteins, including phosphorylated IkBa with a significant reduction of p65 subunit nuclear translocation. Altogether, our preclinical data support the rationale for in vivo testing of ixazomib in EBV-associated B-cell neoplasms. Implications: This preclinical study supports the use of oral proteasome inhibitor ixazomib for targeting NF-kB signaling in the treatment of EBV-associated B-cell neoplasms.