Olverembatinib (HQP1351) Enhances Antitumor Effects of Chemotherapy in Philadelphia Chromosome-Positive (Ph⁺) Acute Lymphoblastic Leukemia (ALL)

Introduction

Ph⁺ ALL is the most common subtype of B-cell- (B-) ALL in adults. BCR-ABL1 tyrosine kinase inhibitors (TKIs) are effective against chronic myeloid leukemia (CML) cells. However, treatment with TKIs fails to maintain disease remission in Ph⁺ B-ALL. Although the complete hematologic remission rate is very high, cytogenetic and molecular remission rates are low, so that TKIs are still considered as complements to chemotherapy and bridges to allogeneic stem cell transplantation. Olverembatinib is a novel, third-generation TKI with more potent activity against BCR-ABL1 and overcomes various resistant mutations, including the “gatekeeper” T315I, which confers resistance against all first- and second-generation TKIs. The aim of this study was to assess whether olverembatinib combined with chemotherapeutic agents vincristine or doxorubicin can promote anti-cancer effects in Ph⁺ ALL cells and explore the potential mechanism of action of the combinations.

Methods

Cell-based antiproliferation assays to evaluate the activities of olverembatinib alone or in combination with vincristine or doxorubicin were conducted using the CellTiter-Glo® Luminescent Cell Viability assay kits. Drug induced cell apoptosis was measured by flow cytometry. Potential mechanism of action analysis was conducted using western blot to evaluate the protein expression involved in BCR-ABL1 and apoptosis signaling pathways.

Results

Cell-based antiproliferation studies showed synergistic activity of olverembatinib in combination with vincristine or doxorubicin in Ph⁺ ALL SUP-B15 cells compared with single agents after 72 hours of treatment. The percentage of apoptotic cells induced by 24-hour treatment of olverembatinib (100 nM), vincristine (300 nM), and the combination were 27.7%, 27.2%, and 40.7%, respectively, while the percentage of apoptotic cells induced by 24-hour treatment of doxorubicin (100 nM) alone and in combination with olverembatinib (100 nM) were 35.3 and 74.1, respectively (apoptotic cells % in DMSO control group is 6.74). The combination significantly increased cell apoptosis compared with single agents ( p < 0.0001). Mechanistically, the combination of olverembatinib with vincristine showed synergistic effects in inhibiting protein expression and phosphorylation of BCR-ABL1, and downstream signal transducer and activator of transcription 5 (STAT5). The synergistic effects were also seen in decreased phosphorylation of AKT and ERK1/2. In addition, the combination significantly decreased protein levels of antiapoptotic MCL-1, BCL-2, and BCL-xL and increased protein levels of proapoptotic BAX and p53 upregulated modulator of apoptosis (PUMA) in a dose-dependent manner, which led to marked augmentation of cleavage of caspase-3 and poly (ADP-ribose) polymerase 1 (PARP). A similar pattern was also observed when olverembatinib was combined with doxorubicin.

Conclusions

Olverembatinib, a novel, third-generation TKI, in combination with chemotherapeutic agents vincristine or doxorubicin decreased MCL-1, BCL-2, and BCL-xL and increased BAX and PUMA in a dose-dependent manner, the combinations have demonstrated synergistic antitumor effects by enhancing apoptosis and antiproliferation in Ph⁺ ALL cells, which may provide an alternative approach for treatment of patients with Ph⁺ ALL.