The Multi-Kinases Inhibitor ARQ531 Enhanches Anti-MM Activity of Imids By Dual Deregulation of MAP- and Cyclin-Dependent Kinases Activities

Introduction: Kinases inhibitors are emerging as promising therapeutic tools for various blood tumors. We previously reported that a novel small tyrosine kinase inhibitor, ARQ531, constrains leukemia cells proliferation and survival by disrupting multiple tumor-addicted programs based on its kinase inhibition profile. As result we pursued its application in pre-clinical models of Multiple Myeloma (MM).

Methods: Inhibitory effects of ARQ531 on cell viability were investigated in a panel of MM cell lines and primary tumor cells (collected from NDMM and RRMM patients) by CellTiterGlo luminescent assay over a range of drug concentrations and time. Specific transcriptomic profiling of ARQ531-treated MM cells was performed by RNA-Seq analysis. Molecular mechanism of this small molecule on MM cells was further investigated by qPCR and western blot analyses. The therapeutic efficacy of ARQ531 combination with different anti-MM drugs was also explored and CalcuSyn software was employed to confirm synergistic effects. Mice engrafted with MM cells were used to determine in-vivo anti-MM activity of ARQ531 in combination with lenalidomide.

Results: ARQ531 inhibited cell viability of MM cell lines (n=20) with IC50 value of 3±1 µM. Furthermore, inhibitory effects of ARQ531 on cell viability were evaluated in a panel of primary MM cells with different mutational status (including those with RAS mutations), with an IC50s value ranging from 0.9 to 4 µM. Consistent with the effect on cell viability, ARQ531 increased the apoptotic rate of MM cells tested. Moreover, anti-MM effects of ARQ531were not reduced in presence of bone marrow stromal cells (BMSCs), and, more importantly such treatment showed a good therapeutic window. A transcriptome profiling analysis of ARQ 531-treated cells demonstrates wide oncogenic transcriptional programs dysregulation, as well as specific interference with kinases involved in cell cycle progression including MAP Kinases and CDK. Given that these kinases are targetable resistance mechanisms for immunomodulatory drugs (IMiDs) in MM, we combined ARQ531 with lenalidomide, pomalidomide or iberdomide observing synergistic effects. Different gene-editing approaches further supported ARQ531-identified profiling as crucial for observed anti-MM activity of tested drugs. We also confirmed that co-treatment in vivo leads to impaired engraftment and prolonged survival in a MM xenograft mouse model, by disrupting key cell proliferation pathways including c-MYC.

Conclusions: Our data show that the small multi-kinases inhibitor ARQ531 has a promising therapeutic activity against MM in preclinical models thus supporting the feasibility of targeting oncogenic driven programs in MM cells with ARQ531 alone or in combinations with IMiDs.

Lemoli:AbbVie: Consultancy; Janssen: Consultancy; Jazz: Consultancy; Novartis: Consultancy; Daiichi Sankyo: Consultancy; Servier: Consultancy; Celgene: Research Funding; Stemline Therapeutics: Consultancy.