A Combination of Alectinib and DNA-Demethylating Agents Synergistically Inhibits Anaplastic-Lymphoma-Kinase-Positive Anaplastic Large-Cell Lymphoma Cell Proliferation

SIMPLE SUMMARY: Tyrosine kinase inhibitors (TKIs) targeting anaplastic lymphoma kinase (ALK), such as crizotinib and alectinib, provide favorable clinical responses in human malignancies driven by ALK fusion proteins, including ALK-positive anaplastic large cell lymphoma (ALK(+) ALCL) and non-small cell lung carcinoma (ALK(+) NSCLC). ALK TKIs were approved for clinical use in ALK(+) NSCLC patients prior to being approved for use in individuals with ALK(+) ALCL. Although most ALK(+) NSCLC patients initially respond to crizotinib and alectinib therapy, they relapse after several years on this therapy. Here, we investigated whether a combination of alectinib and DNA-demethylating agents could have synergistic efficacy for the treatment of ALK(+) ALCL patients. We found that the combination of alectinib and OR-2100, an orally bioavailable decitabine prodrug, synergistically suppressed ALCL cell proliferation, which was accompanied by gene expression reprograming. Therefore, alectinib and OR-2100 combination therapy has the potential to improve treatment outcomes in patients with ALK(+) ALCL. ABSTRACT: The recent evolution of molecular targeted therapy has improved clinical outcomes in several human malignancies. The translocation of anaplastic lymphoma kinase (ALK) was originally identified in anaplastic large-cell lymphoma (ALCL) and subsequently in non-small cell lung carcinoma (NSCLC). Since ALK fusion gene products act as a driver of carcinogenesis in both ALCL and NSCLC, several ALK tyrosine kinase inhibitors (TKIs) have been developed. Crizotinib and alectinib are first- and second-generation ALK TKIs, respectively, approved for the treatment of ALK-positive ALCL (ALK(+) ALCL) and ALK(+) NSCLC. Although most ALK(+) NSCLC patients respond to crizotinib and alectinib, they generally relapse after several years of treatment. We previously found that DNA-demethylating agents enhanced the efficacy of ABL TKIs in chronic myeloid leukemia cells. Moreover, aberrant DNA methylation has also been observed in ALCL cells. Thus, to improve the clinical outcomes of ALK(+) ALCL therapy, we investigated the synergistic efficacy of the combination of alectinib and the DNA-demethylating agent azacytidine, decitabine, or OR-2100 (an orally bioavailable decitabine derivative). As expected, the combination of alectinib and DNA-demethylating agents synergistically suppressed ALK(+) ALCL cell proliferation, concomitant with DNA hypomethylation and a reduction in STAT3 (a downstream target of ALK fusion proteins) phosphorylation. The combination of alectinib and OR-2100 markedly altered gene expression in ALCL cells, including that of genes implicated in apoptotic signaling, which possibly contributed to the synergistic anti-ALCL effects of this drug combination. Therefore, alectinib and OR-2100 combination therapy has the potential to improve the outcomes of patients with ALK(+) ALCL.