Last month the FDA approved two new drugs for cancer, both drugs target cancers with specific genetic mutations which made geneticists and oncologists optimistic on the future of cancer therapy.
The first drug is Vitrakvi (larotrectinib) which treats adults and pediatric patients whose cancers have a specific genetic mutation (biomarker).
This drug belongs to a new class of cancer drugs that are called “Tissue Agnostic” which are used to treat cancers based on a common biomarker across different types of cancers rather than the location of the tumor in the body, it is the second drug of this type to be approved by the FDA.
Vitrakvi will be used to treat adult and pediatric patients with solid tumors that have a neurotrophic receptor tyrosine kinase (NTRK) gene fusion without acquired resistance mutation. NTRK is a gene family that encodes tropomyosin receptor kinases (Trk) which can be fused to other genes abnormally leading to increased growth signals that lead to cancer, these fusions are rare but can occur in different types of cancers like lung, thyroid, and salivary gland cancers.
For patients to be eligible for Vitrakvi treatment, their tumors must be metastatic, cannot be surgically removed and no other treatment is available, or the tumor progressed after treatment.
The FDA approved Vitrakvi based on three clinical trials of 55 pediatric and adult patients that showed 75% overall response rate lasting from 6 months to one year.
Reported side effects include dizziness, fatigue, nausea, vomiting and increased ALT & AST liver enzymes in the blood, so doctors are advised to monitor patients levels of ALT & AST enzymes during the first month of treatment. Vitrakvi cannot be taken during pregnancy or breastfeeding as it harms the fetus or newborn baby.
The second drug approved is Xospata (gilteritinib) which is indicated for the treatment of adult patients who have relapsed or refractory acute myeloid leukemia (AML) with FLT3 mutation. FLT3 is a receptor tyrosine kinase with an essential role in hematopoietic stem cell proliferation.
“Approximately 25 to 30 percent of patients with AML have a mutation in the FLT3 gene. These mutations are associated with a particularly aggressive form of the disease and a higher risk of relapse,” said Richard Pazdur, M.D., director of the FDA’s Oncology Center of Excellence and acting director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research. “Xospata targets this gene and is the first drug to be approved that can be used alone in treating patients with AML having FLT3 mutation who have relapsed or who do not respond to initial treatment.”
Xospata was approved based on a clinical trial of 138 patients with relapsed or refractory AML with FLT3 mutation, 21% of patients showed complete remission ( no evidence of disease), and 31% out of the patients who required a blood or platelets transfusion became transfusion free for at least 56 days.
Some of the side effects reported were muscle and joint pain, fatigue, and elevated liver enzymes. Pregnant and breastfeeding women should not take Xospata as it may cause harm to the fetus or the newborn baby.
Another drug for AML was also approved by the FDA recently “Daurismo (glasdegib)” for AML patients who are 75 years of age or older or who have chronic diseases.