Tipifarnib as a Precision Therapy for HRAS-Mutant Head and Neck Squamous Cell Carcinomas

Area of Science:

• Oncology
• Molecular Biology
• Pharmacology

Background:

• Farnesyltransferase (FTase) inhibitors are being investigated for cancer therapy.
• HRAS mutations are implicated in various cancers, including head and neck squamous cell carcinoma (HNSCC).
• Tipifarnib is a selective FTase inhibitor with potential anti-cancer activity.

Purpose of the Study:

• To characterize the activity of tipifarnib in HRAS-mutant and wild-type HNSCC xenograft models.
• To investigate the mechanistic basis for tipifarnib's efficacy in HRAS-mutant HNSCC.
• To evaluate tipifarnib as a potential precision therapeutic for HNSCC harboring HRAS mutations.

Main Methods:

• Treatment of HRAS-mutant and wild-type HNSCC xenograft models with tipifarnib.
• Analysis of HRAS protein localization, cell proliferation, survival, and spheroid formation.
• In vivo efficacy studies in patient-derived xenograft (PDX) models.
• Assessment of MAPK pathway signaling, apoptosis, and neovascularization.
• Bioinformatics and quantitative image analysis to evaluate squamous cell differentiation.

Main Results:

• Tipifarnib displaced HRAS from cell membranes in both mutant and wild-type cells.
• Tipifarnib selectively inhibited proliferation, survival, and spheroid formation in HRAS-mutant HNSCC cells.
• Tipifarnib induced tumor stasis or regression in all tested HRAS-mutant xenografts but not in HRAS wild-type xenografts.
• Mechanistically, tipifarnib reduced MAPK signaling, inhibited proliferation, induced apoptosis, and abrogated neovascularization.
• FTase inhibition by tipifarnib promoted squamous cell differentiation in HNSCC PDXs.

Conclusions:

• HRAS is a druggable target in HNSCC through FTase inhibition.
• Tipifarnib demonstrates significant preclinical efficacy against HRAS-mutant HNSCC.
• Tipifarnib represents a potential precision therapeutic option for HNSCC patients with HRAS mutations.