Exploiting MCL1 Dependency with Combination MEK + MCL1 Inhibitors Leads to Induction of Apoptosis and Tumor...

Area of Science:

• Oncology
• Molecular Biology
• Cancer Therapeutics

Background:

• BH3 mimetics targeting BCL2 proteins have limited efficacy as single agents in solid tumors.
• Their potential relies on enhancing responses to chemotherapy and targeted treatments.
• Understanding dependencies on BCL2 family proteins is crucial for combination therapies.

Purpose of the Study:

• To investigate the efficacy of novel MCL1 inhibitors in combination with MEK inhibitors.
• To explore the role of differential BCL2 protein binding in BH3 mimetic susceptibility.
• To develop a novel therapeutic strategy for KRAS-mutant NSCLC.

Main Methods:

• Utilized a novel class of potent and selective MCL1 inhibitors.
• Tested concurrent MEK and MCL1 inhibition in KRAS-mutant NSCLC models.
• Assessed susceptibility to BH3 mimetics targeting MCL1 or BCL-xL based on proapoptotic protein binding.
• Investigated the effect of transient BCL-xL inhibitor exposure on MEK + MCL1 blockade efficacy.

Main Results:

• Concurrent MEK + MCL1 inhibition induced apoptosis and tumor regression in KRAS-mutant NSCLC models.
• Models resistant to MEK inhibition alone responded to the combination therapy.
• Differential binding of proapoptotic BCL2 proteins determined sensitivity to MCL1 or BCL-xL inhibitors.
• Prior BCL-xL inhibition augmented the efficacy of dual MEK + MCL1 blockade.

Conclusions:

• Concurrent MEK + MCL1 inhibition is a promising strategy for KRAS-mutant NSCLC.
• Understanding MCL1 vs. BCL-xL dependency is key for prioritizing BH3 mimetic combinations.
• A novel strategy integrating BCL-xL and MCL1 inhibitors enhances efficacy in MEK-treated KRAS-mutant NSCLC.