Primary Effusion Lymphoma (PEL) is an aggressive malignancy caused by the Kaposi sarcoma associated herpesvirus (KSHV). PEL patients rarely respond to conventional chemotherapy and their prognosis is poor, with a median survival of less than six months. The most promising treatment strategies in these patients combine anti-viral treatments with new agents including chemicals and cytokines. Here, we investigated the efficacy of lenalidomide (Lena), an immune modulator with significant clinical activity in a large number of hematological malignancies, and arsenic trioxide (As), a potent agent in acute promyelocytic leukemia and HTLV-I associated adult T cell leukemia.

We used three PEL cell lines (BC-1, BC-3 and BCBL-1 which are KSHV+/EBV- malignant B cells derived from PEL patients) and one PEL-negative control cell line (RAJI as a KSHV- malignant B cell line). We demonstrate that the combination of As and Lena resulted in growth inhibition in BC-1 and BC-3 cells and to a lesser degree in BCBL-1 cells while no effect was observed in RAJI cells. This growth arrest was associated with induction of massive apoptosis and a substantial upregulation of phosphorylated and total p53 protein levels. Furthermore, As/Lena inhibited the expression of latent viral transcripts (LANA-1, LANA-2, v-FLIP and v-Cyclin) and proteins (LANA-1/LANA-2) in all tested PEL cells.

Finally, and while Lena alone did not have any inhibitory effect on in vitro treated PEL cells, single agent Lena treatment doubled survival of BC-3 PEL mice and significantly prolonged survival in 75% of BCBL-1 PEL mice and led to cure of the remaining 25%. More importantly, combination of As and Lena was highly synergistic and cured 25% and 75% of BC-3 and BCBL-1 PEL mice respectively. These results provide a rational for the therapeutic use of the combination As/Lena in PEL patients.

Disclosures

No relevant conflicts of interest to declare.

Author notes

*

Asterisk with author names denotes non-ASH members.

Sign in via your Institution