Orelabrutinib and venetoclax synergistically induce cell death in double-hit lymphoma by interfering with the crosstalk between the PI3K/AKT and p38/MAPK signaling.

Purpose: Double-hit lymphoma (DHL) is a rare and aggressive mature B-cell malignancy with concurrent MYC and BCL2 rearrangements. When DHL becomes relapsed or refractory, it becomes resistant to the majority of therapeutic approaches and has subpar clinical results. Therefore, innovative therapeutics for this particular patient population are urgently needed.

Methods: Orelabrutinib, a new oral BTK inhibitor, combined with the Bcl-2 inhibitor venetoclax, was used to confirm the antitumor effect of DHL. Cell counting kit-8 and Annexin V-FITC/PI assays were used to examine the interaction of this combined regimen on DHL cell lines and primary lymphoma cells. RNA sequencing, EdU incorporation assay, mitochondrial membrane potential assay, and western blotting were employed to explore the molecule mechanism for the cytotoxicity of orelabrutinib with or without venetoclax against DHL cell lines.

Results: In this study, orelabrutinib combined with venetoclax synergistically induced DHL cell death, as evidenced by the inhibition of cell proliferation, the induct of cell cycle arrest, and the promotion of cell apoptosis via the mitochondrial pathway. Orelabrutinib treatment alters genome-wide gene expression in DHL cells. The combined regimen decreases the expression of BTK and Mcl-1, potentially interfering with the activity and crosstalk of PI3K/AKT signaling and p38/MAPK signaling. In addition, the combination of orelabrutinib and venetoclax shows cytotoxic activity in primary B-lymphoma cells.

Conclusion: In summary, these findings reveal a novel therapy targeting BCR signaling and the Bcl-2 family for DHL patients with a poor prognosis.