Project Term
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Constantine Mitsiades, MD, PhD
Dana-Farber Cancer Institute
Boston, MA
United States
Project Summary
At least half of multiple myeloma (MM) patients have mutations of KRAS or NRAS genes and in our preclinical studies, several types of Ras inhibitors slow MM cell growth in lab cultures and in mice, but resistance eventually develops. Gene-editing or activation (CRISPR) studies indicate that the mechanisms of this resistance can vary substantially between MM cells with different genomic features but, notably, defects in the Bcl‑2 family of genes are a recurrent theme. We will apply a lab method called dynamic BH3 profiling to determine how Ras inhibitors alter the myeloma cell dependence on Bcl-2 proteins to inform combination-based therapies. The results from these studies will be validated in cell lines and patient samples in the lab and in vivo models to identify the most effective combinations and guide future personalized therapies for people with KRAS or NRAS mutant multiple myeloma.
Lay Abstract
At least half of patients with multiple myeloma (MM), the 2nd most common blood cancer, have mutations in the KRAS or NRAS genes. Drugs targeting these mutations have had clinical success in solid tumors, but are not tested yet in MM. We studied several types of inhibitors that block the activity of mutant KRAS or NRAS. We found that these drugs slow the growth of MM cells in lab cultures and in mice, but, over time, MM cells developed ways to resist them. To understand this resistance, we used powerful CRISPR methods to turn thousands of genes on or off across many MM cell lines. This allowed us to see which genes made MM cells more vs. less sensitive to treatment. We find that these sets of genes varied substantially depending on each cell’s genomic features. One common pattern involved the Bcl‑2 family of genes, which control whether cells live or die. Specifically, MM cells with increased activity of “survival-promoting” or those that lost “cell-death” Bcl‑2 family genes, were better able to survive Ras inhibitor treatment. Interestingly, these survival patterns were not always predicted by analysis of the expression or changes of expression of these genes during Ras inhibitor treatment. This indicates that the MM cell’s protective mechanisms against these new compounds are more complex than expected and require a more detailed functional assessment of how close these Ras inhibitors can push MM cells over the “point of no return” for cell death. Our research will address these questions using dynamic BH3 profiling, a method designed to quickly measure how different treatments push tumor cells closer to the point where they can die. By testing this in multiple lab models of MM with different mutations or other genomic features, either present spontaneously or engineered by us in the lab, we can learn which combinations of Ras inhibitors with other anti-MM therapies are most likely to succeed. We will test a variety of treatments, both new drugs that target the KRAS or NRAS genes and standard medicines already used in multiple myeloma, such as thalidomide-like compounds, proteasome inhibitors, steroids, and immune-based therapies like CAR T cells, bispecific antibodies, and anti CD38 antibodies. Using gene-edited myeloma cells, we can also study how certain cell-survival genes, such as members of the Bcl 2 family or TP53, influence the MM cells’ response to Ras inhibitors. To confirm these findings, we will test samples taken directly from patients at different stages of MM to see if similar patterns occur. Finally, the best drug combinations—those that most effectively push MM cells toward death in the lab—will be tested in advanced preclinical models that closely mimic the human bone marrow environment. This research aims to identify personalized treatment strategies for people with KRAS‑ or NRAS‑mutant MM by predicting which combinations of Ras inhibitors with other anti-MM therapies can best overcome resistance and improve therapy outcomes.
Program