Transcriptional Heterogeneity Overcomes Super-Enhancer Disrupting Drug Combinations in Multiple Myeloma

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Multiple myeloma (MM) pathogenesis involves MYC and IRF4, regulated by super-enhancers.
• IKZF1 and IKZF3 proteins bind super-enhancers and are targeted by immunomodulatory imide drugs (IMiDs).
• IMiD resistance in MM can be mediated by sustained MYC and IRF4 expression.

Purpose of the Study:

• To investigate a combination therapy of IMiDs and EP300 inhibition for MM.
• To explore mechanisms of IMiD resistance in MM.
• To identify novel therapeutic strategies for overcoming drug resistance in MM.

Main Methods:

• In vitro and in vivo studies combining IMiDs with EP300 inhibitors.
• Analysis of MYC and IRF4 downregulation.
• Assessment of synergistic killing of myeloma cells.
• Investigation of AP-1 factor involvement in IMiD resistance.

Main Results:

• The combination of IMiDs and EP300 inhibition synergistically killed myeloma cells in vitro and in vivo.
• This combination led to greater downregulation of MYC and IRF4 compared to single agents.
• A previously unrecognized mechanism of IMiD resistance involving AP-1 factors (BATF) was identified.
• The combination therapy demonstrated an increased therapeutic window.

Conclusions:

• The combination of IMiDs and EP300 inhibition is a potent therapeutic strategy for MM.
• Targeting IKZF1-bound super-enhancers offers a promising approach for MM treatment.
• AP-1 factors represent a novel mechanism of IMiD resistance in MM.