MST1 Inhibitors and Multiple Myeloma

Multiple Myeloma Overview

• Definition: Multiple myeloma (MM) is a hematological malignancy characterized by abnormal clonal plasma cell growth in the bone marrow.
• Associated Symptoms:
  • Destructive bone lesions
  • Acute kidney injury
  • Hypercalcemia
  • Anemia
  • End-organ failure

Epidemiology of MM

• Commonality: Second most common hematological malignancy worldwide
• Statistics:
  • Accounts for 1% of all cancers and 10% of hematological malignancies
  • Average age of onset: 60-70 years
  • Incidence rate in Canada: ~54 cases per million individuals
  • Projections for 2024: 4100 new diagnoses and 1750 deaths

Developmental Stages of MM

• Monoclonal Gammopathy of Undetermined Significance (MGUS): Asymptomatic presence of intact monoclonal immunoglobulins (M protein). Usually benign but can progress.
• Smoldering Multiple Myeloma (SMM): Intermediate asymptomatic stage characterized by higher levels of M protein and/or plasma cell infiltration.
• Fully Progressed Disease: Characterized by abnormal clonal plasma cells and clinical symptom presentation.

Molecular Characteristics of MM

• Gene Translocations:
  • Key Translocations: IgH-CCND (e.g., t(11;14)), IgH-NSD2 (e.g., t(4;14)), IgH-MAF and MAFB (e.g., t(14;16), t(14;20))
  • These translocations lead to the upregulation of oncogenes and disease progression.
  • Cyclin D genes (CCND1-3) are influenced by the IgH enhancer, increasing cyclin production and promoting cell cycle progression through hyperphosphorylation of RB.
• 17p Deletions and P53 Mutations:
  • Deletion associated with poor outcomes; ~10% of patients have 17p deletions affecting the TP53 gene, a crucial tumor suppressor.

Role of MYC in MM

• MYC Overexpression: Found in 20-40% of newly diagnosed MM.
  • Functions include cell proliferation, apoptosis, differentiation, migration, and metabolism.
  • MYC can be dysregulated through translocation, mutations, and active signaling pathways.

Hippo Pathway in MM

• TAZ Regulation: TAZ is often hypermethylated in MM, not mutated. Its reinstatement decreases MYC expression, inducing cell death.

Research Focus: MST1 Inhibitors

• Purpose: Evaluating novel MST1 inhibitors as a therapeutic strategy in MM.
• MST1's Role: Downregulates TAZ, suggesting inhibition could have potential therapeutic benefits.

Research Objectives

1. Examine mRNA and protein levels of MST1, YAP, and TAZ in human myeloma cell lines (HMCLs).
2. Determine pharmacological action of novel MST1 inhibitors, including dose-response and changes in TAZ expression post-treatment.
3. Investigate synergistic effects with traditional therapies like bortezomib and lenalidomide, or agents that induce TAZ expression (e.g., Azacytidine).
4. Potential efficacy assessment against patient-derived myeloma cells.

Hypotheses

1. MST1 inhibitors will exhibit anti-myeloma effects at nanomolar doses.
2. Synergistic relationship expected between novel inhibitors and other drugs affecting TAZ signaling.
3. Responding HMCLs will show reduced MST1 and increased TAZ expression post-treatment.

Methodology Overview

• Model Organisms: HMCLs including KHM1B, Delta47, KMS27, KMS11, KMM1, LP-1, U266; A-549 as TAZ reference.
• RT-qPCR: RNA extraction, cDNA synthesis, followed by PCR steps (denaturation, annealing, extension).
• Western Blotting: Analyze protein expression through SDS-PAGE and transfer to nitrocellulose membrane for imaging.

Drug-Based Therapies for MM

• Drug Classes:
  • Alkylating agents
  • Immunomodulatory drugs
  • Corticosteroids
  • Proteasome inhibitors
• Immunotherapies Used:
  • CAR-T cell therapy
  • Antibody-drug conjugates
  • Bispecific antibodies
  • Monoclonal antibodies
• Common Drug Combinations: Lenalidomide/bortezomib/dexamethasone (VRd), Daratumumab/lenalidomide/dexamethasone (DRd).

Decitabine Overview

• Mechanism: Hypomethylating agent; integrates into DNA during replication, forming irreversible bonds to DNMTs, leading to global hypomethylation.

Autologous Stem Cell Transplant (ASCT)

• Eligibility: Generally under age 75 in the U.S. or 65 in Europe; involves induction therapy, stem cell harvesting, and subsequent transplantation followed by maintenance therapy (e.g., bortezomib or lenalidomide).