MTAP as an emerging biomarker in thoracic malignancies

Area of Science:

• Oncology
• Molecular Diagnostics
• Cancer Biomarkers

Background:

• S-methyl-5'-thioadenosine phosphorylase (MTAP) deficiency is increasingly recognized in various cancers, notably non-small cell lung cancer (NSCLC).
• The MTAP gene resides in the frequently deleted chromosomal region 9p21.3, a common event in many human cancers, including pleural mesotheliomas.
• MTAP loss is a significant diagnostic marker in thoracic tumors and an emerging predictive biomarker for therapeutic response.

Purpose of the Study:

• To review the current literature on the role of MTAP in thoracic tumors.
• To evaluate diagnostic and predictive testing methods for MTAP deficiency.
• To discuss the implications of MTAP loss as a biomarker for immune checkpoint inhibitor (ICI) treatment and novel targeted therapies.

Main Methods:

• Review of existing scientific literature on MTAP in thoracic oncology.
• Evaluation of diagnostic techniques including immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS).
• Analysis of MTAP's role in predicting response to ICI therapy and targeted treatments.

Main Results:

• MTAP deficiency is observed in approximately 13% of NSCLC cases.
• MTAP loss negatively predicts response to ICI treatment by affecting the tumor microenvironment.
• MTAP deficiency creates a synthetic lethality vulnerability with PRMT5, making it a target for novel therapies.

Conclusions:

• Loss of MTAP expression via IHC is a cost-effective and practical surrogate marker for 9p21 loss.
• MTAP serves as a crucial predictive biomarker for both immunotherapy and emerging targeted treatments in NSCLC and other cancers.
• The implementation of MTAP IHC in routine diagnostics for thoracic tumors is anticipated due to its emerging clinical significance.