Correcting genes that allow cancerous tumors to grow is the basis behind gene therapy, a relatively new treatment that is largely in experimental stages. The initial goals of gene therapy were to address hereditary genetic disorders, but other factors such as the sun, smoking, chemical exposure, etc., can all damage and change our DNA and the result causes faulty genetic behavior. Mesothelioma is a multifactorial disorder, a disorder that is the result of both inherited genetic mutations and mutations gained through environmental causes. In the case of mesothelioma, the environmental cause is usually exposure to asbestos.
Recently, the FDA approved a genetic-based cancer treatment that could be used on those suffering from mesothelioma. This is because the cancer treatment targets TRK gene fusion, which is a genetic mutation found in mesothelioma and other types of cancer. TRK stands for Tropomyosin Receptor Kinases and is normally expressed in neuronal cells and plays a role in nervous system development and maintenance. These proteins are encoded by the NTRK 1 gene. In TRK fusion cancer, the NTRK gene fuses with an unrelated gene, damaging the gene’s DNA. These gene fusions lead to the over expression of TRK proteins causing cells to over-proliferate and the development of solid tumors.
TRK gene fusions occur in a broad range of tumor types, which include:
- Infantile Fibrosarcoma
- Thyroid Cancer
- High –grade gliomas (pediatric)
- Colon Cancer
- Head and neck squamous cell carcinoma
The recently approved genetic-based cancer treatment larotrectinib, (sold under the brand name Vitrakvi) is a TRK inhibitor and has scientists and researchers hopeful that it can be used to stop cancer growth for those with mesothelioma tumors. The latest study investigated 55 patients with TRK fusion-positive cancers (adults and children), with an age range of 4 months to 76 years. Larotrectinib was administered orally for both adults and children. The overall response rate was 75 percent. At the one year mark, 71 percent of the responses were on going, and 55 percent of patients remained progressions free. Adverse effects from the treatment were minimal. In fact, no patient discontinued the treatment because of adverse effects.
Even though none of the patients investigated in this study were diagnosed with mesothelioma, researchers are hopeful that the potential for tumor shrinkage and deterioration is likely with larotrectinib since the TRK gene fusion is present in mesothelioma. Larotrectinib is an orphan drug, which is a drug developed for a rare disease or condition, affecting less than 200,000 Americans a year. Mesothelioma affects approximately 3,000 Americans every year.
A. Drilon, et. al. “Efficacy of Larotrectinib in TRKFusion–Positive Cancers in Adults and Children,” New England Journal of Medicine (February 2018). [Link]