Project description:The historical lack of pre-clinical models reflecting the genetic heterogeneity of multiple myeloma (MM) hampers advancing therapeutic discoveries. To circumvent this limitation, we have generated fifteen genetically diverse models that developed bone marrow tumors fulfilling MM pathogenesis. Transcriptomic analysis of tumor plasma cells revealed that MYC activation regulates time to progression. Bone marrow cell composition analysis classified myeloma tumors into immune-cold and inflamed categories, which condition immune checkpoint blockade responses in mouse multiple myeloma models.
Project description:Multiple myeloma (MM) continues to be considered incurable, necessitating new drug discovery. The mitotic kinase T-LAK cell-originated protein kinase/PDZ-binding kinase (TOPK/PBK) is associated with proliferation of tumor cells, maintenance of cancer stem cells, and poor patient prognosis in many cancers. In this report, we demonstrate potent anti-myeloma effects of the TOPK inhibitor OTS514 for the first time. OTS514 induces cell cycle arrest and apoptosis at nanomolar concentrations in a series of human myeloma cell lines (HMCL) and prevents outgrowth of a putative CD138+ stem cell population from MM patient-derived peripheral blood mononuclear cells. In bone marrow cells from MM patients, OTS514 treatment exhibited preferential killing of the malignant CD138+ plasma cells compared with the CD138- compartment. In an aggressive mouse xenograft model, OTS964 given orally at 100 mg/kg 5 days per week was well tolerated and reduced tumor size by 48%-81% compared to control depending on the initial graft size. FOXO3 and its transcriptional targets CDKN1A (p21) and CDKN1B (p27) were elevated and apoptosis was induced with OTS514 treatment of HMCLs. TOPK inhibition also induced loss of FOXM1 and disrupted AKT, p38 MAPK, and NF-κB signaling. The effects of OTS514 were independent of p53 mutation or deletion status. Combination treatment of HMCLs with OTS514 and lenalidomide produced synergistic effects, providing a rationale for the evaluation of TOPK inhibition in existing myeloma treatment regimens.
Project description:Raw MS data for pre-published paper: Olomorasib, a highly selective and potent oral inhibitor of KRASG12C, demonstrates robust single agent and combination activity in KRASG12C-mutant models
Project description:Pre-clinical models for prediction of immunotherapy outcomes and immune evasion mechanisms in genetically heterogeneous multiple myeloma
Project description:Resistance to proteasome inhibitors (PIs) is a ubiquitous clinical concern in multiple myeloma. We proposed that signaling-level responses after PI would reveal new means to enhance efficacy. Unbiased phosphoproteomics after the PI carfilzomib surprisingly demonstrated the most prominent phosphorylation changes on spliceosome components. Spliceosome modulation was invisible to RNA or protein abundance alone. Transcriptome analysis demonstrated broad-scale intron retention suggestive of PI-specific splicing interference. Direct spliceosome inhibition synergized with carfilzomib and showed potent anti-myeloma activity. Functional genomics and exome sequencing further supported the spliceosome as a specific vulnerability in myeloma. Our results propose splicing interference as an unrecognized modality of PI mechanism, reveal additional modes of spliceosome modulation, and suggest spliceosome targeting as a promising therapeutic strategy in myeloma.
Project description:Multiple myeloma is a plasma cell malignancy that is susceptible to drugs targeting protein homeostasis such as thalidomide analogues and proteasome inhibitors. Thalidomide analogues modulate the activity of DDB1/CUL4 E3-ligase complexes to perturb substrate recognition and proteasomal degradation thereof. We hypothesised that the cellular pool of DDB1/CUL4 associated factors (DCAFs) may mediate other essential plasma cell processes and offer new targets for therapeutic intervention. Unbiased genetic screening identified DCAF1 (also known as Vpr-binding protein; VPRBP) as essential for myeloma cell survival with a multidomain structure offering several distinct opportunities for drug development. Utilising B32B3, a previously disclosed DCAF1 kinase inhibitor as a template, we developed a series of analogues with enhanced anti-myeloma potency. As anti-myeloma activity did not associate with dephosphorylation of known DCAF1 kinase substrates, we correlated drug-induced cellular phenotypes with whole-genome CRISPR/Cas9 resistance screening to further define mechanistic activity. These studies identified B32B3 analogues as microtubular destabilising agents with potential DCAF1 kinase independent properties and in vivo efficacy in multiple myeloma and lymphoma.
Project description:Multiple myeloma (MM) is a neoplasia of bone marrow (BM) plasma cells that remains largely incurable with current treatment. Advancing therapeutic discoveries has been hampered by the lack of genetically heterogeneous models of MM. To circumvent this limitation, we engineered fifteen mouse models carrying combinations of eight MM genetic drivers, which fulfilled the pathogenesis of human disease including progression from premalignant states under immune surveillance. Integrative analyses of ⁓500 mice and ⁓1,000 patients revealed a MAPK-MYC genetic pathway that regulates time to progression and immune escape mechanisms across genetically heterogeneous tumors. During progression, MYC-dependent and independent remodeling of the BM microenvironment divided MM into immune categories with predominance of selected T-cell subpopulations, which dictated immunotherapy responses. Experimental targeting of the cytotoxic or immunosuppressive T-cell states observed in refractory MM patients enhanced immunotherapy effectiveness. Our resource enabled characterization of MM cell-intrinsic and immunological traits at unprecedented levels, which will accelerate the translation of personalized immunotherapy.