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KRASG12V Degraders Provide a Potential Therapeutic Opportunity in Lung Adenocarcinoma
Santiago Garcia Borrego1, Sandra Misale1
1Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, School of Medicine, Johns Hopkins University, Baltimore, Maryland.
Abstract:
Mutant KRAS inhibition has revolutionized the treatment of lung adenocarcinoma. Unfortunately, responses to this form of targeted therapy are often of limited duration because of the development of resistance. Targeted protein degradation, including using PROTACs (PROteolysis-TArgeting Chimeras), presents an alternative approach to targeting oncogenic drivers in cancer. In this issue of Cancer Research, Martín and colleagues developed a dTAG-KRASG12V syngeneic mouse model that allows for the study of the effects of degrading the KRASG12V oncoprotein in vivo. The authors discovered that degrading the KRASG12V oncoprotein leads to regression of the resulting lung adenocarcinoma tumors. Most of the regression was based on cancer cell-intrinsic responses, although the tumor microenvironment also underwent substantial remodeling. Despite the initial efficacy of the treatment, the authors found that prolonged PROTAC KRAS degrader treatment eventually resulted in relapse. Resistance to PROTAC treatment seemed to be driven by dysregulation of the ubiquitin-proteasome system that is required for the activity of the PROTAC degraders. Despite developing resistance to the PROTAC degraders, the resulting tumors were still dependent on the KRAS oncoprotein, meaning that they were still sensitive to conventional KRAS inhibitors. Thus, PROTACs that degrade the KRAS oncoprotein are a promising modality for the treatment of lung adenocarcinomas. Resistance to PROTACs may differ from conventional KRAS inhibitors, suggesting potential strategies for overcoming such resistance. See related article by Martín et al., p. 4115.
Insights
Targeted protein degraders, PROTACs, effectively reduced lung adenocarcinoma tumors by degrading KRASG12V. However, resistance emerged due to ubiquitin-proteasome system dysregulation, though tumors remained sensitive to conventional KRAS inhibitors.
Area of Science:
- Oncology
- Molecular Biology
- Drug Development
Background:
- Mutant KRAS is a key driver in lung adenocarcinoma, but targeted therapies face resistance.
- Targeted protein degradation using PROTACs offers a novel strategy against oncogenic drivers.
- Understanding resistance mechanisms is crucial for developing durable cancer treatments.
Purpose of the Study:
- To investigate the efficacy of PROTAC-mediated KRASG12V degradation in a syngeneic lung adenocarcinoma mouse model.
- To explore the mechanisms of tumor regression and resistance development following PROTAC treatment.
- To evaluate the potential of PROTACs as a therapeutic strategy for KRAS-driven lung cancers.
Main Methods:
- Development of a dTAG-KRASG12V syngeneic mouse model for in vivo studies.
- Administration of PROTAC KRAS degraders to assess tumor response.
- Analysis of tumor regression, cancer cell-intrinsic responses, and tumor microenvironment remodeling.
- Investigation of resistance mechanisms, including ubiquitin-proteasome system function.
Main Results:
- Degradation of KRASG12V led to significant regression of lung adenocarcinoma tumors.
- Tumor regression was primarily driven by cancer cell-intrinsic effects, with concurrent tumor microenvironment remodeling.
- Prolonged PROTAC treatment resulted in tumor relapse, associated with resistance mechanisms.
- Resistance to PROTACs involved dysregulation of the ubiquitin-proteasome system, but tumors remained sensitive to conventional KRAS inhibitors.
Conclusions:
- PROTACs targeting KRASG12V are a promising therapeutic approach for lung adenocarcinoma.
- Emergence of resistance to PROTACs may involve distinct mechanisms compared to conventional KRAS inhibitors.
- Understanding these resistance pathways could inform combination strategies to overcome treatment failure.