Multikinase inhibitor olverembatinib (HQP1351) is efficacious and synergizes with BTK inhibitor acalabrutinib in mantle cell lymphoma (MCL) preclinical models

Background: MCL is a rare, aggressive type of non-Hodgkin lymphoma. Although Bruton tyrosine kinase (BTK) inhibitors have transformed MCL treatment, response to monotherapy is limited, and efforts are underway to develop combination therapies. Olverembatinib, an investigational multikinase inhibitor (approved in China for chronic myeloid leukemia), inhibits Src-family kinase Lyn, which is essential for B-cell receptor (BCR) signaling and B-cell proliferation, differentiation, and activation. Hypothesizing that dual inhibition of Lyn and BTK pathways enhances antitumor effects, we evaluated olverembatinib combined with acalabrutinib in preclinical MCL models and explored potential mechanisms of action (MOAs). Methods: MCL cell lines Mino and Rec-1 were selected for in vitro growth inhibition assessments. CellTiter-Glo ® assays were conducted to evaluate antiproliferative activity. Apoptosis and cell cycle arrest were assayed by flow cytometry. MOAs were examined by tyrosine phosphoproteomic analysis and confirmed by western blotting. In vivo activity was evaluated in a subcutaneous cell-derived xenograft (CDX) mouse model. Results: Olverembatinib potently inhibited MCL cell proliferation, with respective IC 50 values of 15 and 25 nM in Mino and Rec-1 cells. When combined with acalabrutinib, olverembatinib showed synergistic antiproliferative effects in both cell lines (respective Loewe scores = 10.04 and 10.92). The combination also significantly increased percentages of apoptotic cells (Mino, p < 0.001; Rec-1, p < 0.01), and significantly induced G0/G1 cell cycle arrest versus either agent alone (Mino, p < 0.01; Rec-1, p < 0.0001). On tyrosine phosphoproteomic analysis, olverembatinib inhibited kinase activities of Lyn, Fyn, Lck, Syk, and BTK, leading to potent inhibition of BCR signaling. Acalabrutinib inhibited BTK and other Tec-family kinases (e.g., Tec, Itk). Combining both agents potentiated inhibition of BCR and NFkB pathways. These results were further confirmed by western blot analysis. Olverembatinib inhibited phosphorylation of Lyn and its downstream BTK, while the combination further downregulated NF-kB activity. The combination also significantly suppressed cell cycle-promoting protein CDK6 and increased apoptotic markers PARP and caspase-3. In the Mino CDX model, olverembatinib dose-dependently inhibited tumor growth, with a treatment-to-control (T/C) value of 35.35% at 15 mg/kg, while acalabrutinib (10 mg/kg) exhibited a T/C value of 73.37%. When coadministered, both agents further enhanced antitumor activity (T/C = 18.64%), achieving a synergistic index of 1.39. Conclusions: Olverembatinib is efficacious and synergizes with acalabrutinib in preclinical MCL models. These data provide a rationale for further clinical evaluation of this novel combination therapy in patients with MCL.