Combinatorial approaches for mitigating resistance to KRAS-targeted therapies

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• Mutated KRAS is found in approximately 15% of cancer patients.
• Direct KRAS inhibitors targeting mutations like KRASG12C are advancing in clinical trials, particularly for lung cancer.

Purpose of the Study:

• To investigate the mechanisms of emergent resistance to different classes of Ras-targeted therapies.
• To explore strategies for overcoming resistance and achieving durable responses to KRAS inhibitors.

Main Methods:

• Exposure of cancer models to representative KRAS inhibitors.
• Analysis of Ras signaling reactivation and adaptive responses over time.
• Gene expression profiling to identify resistance signatures.
• Evaluation of combination therapies and salvage approaches.

Main Results:

• Rapid reactivation of Ras signaling was observed within days of inhibitor exposure.
• Distinct gene expression signatures were associated with each inhibitor, commonly involving upregulation of upstream Ras activators.
• Long-term treatment led to evolving adaptive resistance responses.
• Resistance often resulted in cross-desensitization to other anti-cancer therapeutics, limiting salvage options.

Conclusions:

• Emergent resistance to KRAS inhibitors is a significant challenge, characterized by rapid Ras pathway reactivation.
• Combination therapy strategies, specifically triple inhibitor combinations, demonstrated more durable responses in pre-clinical models.
• Further pre-clinical evaluation of novel combination therapies is warranted to overcome resistance to KRAS-targeted treatments.