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Updated: May 7, 2026
A Melanoma Patient-Derived Xenograft Model
Published on: May 20, 2019
The evolution of melanoma resistance reveals therapeutic opportunities
Meghna Das Thakur1, Darrin D Stuart
1Authors' Affiliation: Novartis Institutes for Biomedical Research, Emeryville, California.
Abstract:
The RAS-RAF-MEK-ERK pathway is a key driver of proliferation and survival signals in tumor cells and has been the focus of intense drug development efforts over the past 20 years. The recent regulatory approval of RAF inhibitors and a MAP-ERK kinase (MEK) inhibitor for metastatic melanoma provides clinical validation of tumor dependency on this pathway. Unfortunately, the therapeutic benefit of these agents is often short lived and resistance develops within a matter of months. Preclinical models of resistance to vemurafenib have provided critical insights into predicting, validating, and characterizing potential mechanisms. A key observation has been that vemurafenib-resistant tumor cells suffer a fitness deficit in the absence of drug treatment and this led to the predication that modulating the selective pressure of drug treatment through intermittent dosing could delay or prevent the emergence of resistant tumors. Most importantly, the preclinical data are supported by observations in vemurafenib-treated patients with melanoma providing a strong rationale for clinical testing of alternative dosing regimens.
Insights
Intermittent dosing of RAF inhibitors may delay resistance in melanoma. Preclinical models show resistant cells have a fitness deficit without drug, suggesting intermittent therapy could prevent tumor progression.
Area of Science:
- Oncology
- Pharmacology
- Molecular Biology
Background:
- The RAS-RAF-MEK-ERK pathway is crucial for tumor cell proliferation and survival.
- RAF inhibitors and MEK inhibitors are approved for metastatic melanoma, validating pathway dependency.
- Therapeutic benefits of these inhibitors are often limited by rapid resistance development.
Purpose of the Study:
- To investigate mechanisms of resistance to RAF inhibitors like vemurafenib.
- To explore intermittent dosing strategies to overcome or delay resistance.
- To provide a rationale for clinical testing of alternative dosing regimens.
Main Methods:
- Utilized preclinical models of vemurafenib resistance in melanoma.
- Assessed the fitness of resistant tumor cells in the absence of drug treatment.
- Analyzed clinical observations in vemurafenib-treated melanoma patients.
Main Results:
- Vemurafenib-resistant tumor cells exhibit a fitness deficit when not exposed to the drug.
- This fitness deficit suggests that modulating drug exposure can impact resistance.
- Preclinical findings are supported by clinical observations in patients.
Conclusions:
- Intermittent dosing of RAF inhibitors is a promising strategy to delay or prevent resistance.
- Understanding tumor cell fitness is key to designing effective therapeutic schedules.
- Further clinical investigation of alternative dosing regimens is warranted.
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