Treating myeloma: the future is already here!

Epigenetic Activity of Peroxisome Proliferator-Activated Receptor Gamma Agonists Increases the Anticancer Effect of Histone Deacetylase Inhibitors on Multiple Myeloma Cells

Epigenetic modifications play a major role in the development of multiple myeloma. We have previously reported that the PPARγ agonist pioglitazone (PIO) enhances, in-vitro, the cytotoxic effect of the Histone deacetylase inhibitor (HDACi), valproic acid (VPA), on multiple myeloma cells. Here, we described the development of a new multiple myeloma mouse model using MOLP8 cells, in order to evaluate the effect of VPA/PIO combination on the progression of myeloma cells, by analyzing the proliferation of bone marrow plasma cells. We showed that VPA/PIO delays the progression of the disease and the invasion of myeloma cells in the bone marrow. Mechanistically, we demonstrated that VPA/PIO increases the cleavage of caspase 3 and PARP, and induces the acetylation of Histone 3 (H3). Furthermore, we provided evidence that PPARγ agonist is able to enhance the action of other HDACi such as Vorinostat or Mocetinostat. Using PPARγ antagonist or siPPARγ, we strongly suggest that, as described during adipogenesis, PIO behaves as an epigenetic regulator by improving the activity of HDACi. This study highlights the therapeutic benefit of PIO/VPA combination, compared to VPA treatment as a single-arm therapy on multiple myeloma and further highlights that such combination may constitute a new promising treatment strategy which should be supported by clinical trials.

Modeling progression risk for smoldering multiple myeloma: results from a prospective clinical study

The risk of progression to multiple myeloma (MM) from the precursor condition smoldering MM (SMM) varies considerably among individual patients. Reliable markers for progression to MM are vital to advance the understanding of myeloma precursor disease and for the development of intervention trials designed to delay/prevent MM. The Mayo Clinic and Spanish PETHEMA have proposed models to stratify patient risk based on clinical parameters. The aim of our study was to define the degree of concordance between these two models by comparing the distribution of patients with SMM classified as low, medium and high risk for progression. A total of 77 patients with SMM were enrolled in our prospective natural history study. Per study protocol, each patient was assigned risk scores based on both the Mayo and the Spanish models. The Mayo Clinic model identified 38, 35 and four patients as low, medium and high risk, respectively. The Spanish PETHEMA model classified 17, 22 and 38 patients as low, medium and high risk, respectively. There was significant discordance in overall patient risk classification (28.6% concordance) and in classifying patients as low versus high (p < 0.0001), low versus non-low (p = 0.0007) and high versus non-high (p < 0.0001) risk. There is a need for prospectively validated models to characterize individual patient risk of transformation to MM.