A Step forward in the Direction of Precision Medicine in Oncology
In late 2018, FDA has approved a new cancer drug that is the first to be designed to fight a specific genetic mutation. The new drug, named Vitrakvi is not approved to fight a specific cancer type such as breast, pancreatic or colon cancer but instead, it is designed and approved to treat cancers based on the presence of a certain genetic characteristics. Hence, it can treat many cancer types which carry a certain mutation type known as NTRK fusions. The drug previously known as LOXO-101, developed by Bayer and Loxo Oncology, Inc., is a selective tropomyosin receptor kinase (TRK) inhibitor. The Food & Drug Administration based its approval on three clinical trials among 55 adults and children with 17 cancer types. The overall response rate that includes 55 adults and children with different cancer types, there is a complete or partial shrinkage in tumor in 75% of these individuals and 73% of those who responded stayed progression-free for at least six months and 39% were progression-free for a year or longer.
Previously several drugs such as Keytruda are approved to treat a variety of different cancer types based on genetic mutations but Vitrakvi (generically known as Larotrectinib), is the first drug to be approved from the beginning to treat cancers solely based on the mutation. Vitrakvi treats genetic mutation that involves genes called NTRK genes. Very rarely these genes fuse together and cause the out-of-control growth resulting in tumors. NTRK fusions occur as the result of two pieces of genes, located on different chromosomes fusing together abnormally resulting in a hybrid protein that has enhanced cancer-causing activity. But the hybrid protein is also susceptible to inhibition by drugs like Vitrakvi.
According to a statement issued by FDA, prior to the drug approval, there had been no treatment for cancers that frequently express this mutation, like mammary analogue secretory carcinoma, cellular or mixed congenital mesoblastic nephroma and infantile fibrosarcoma. NTRK fusions also occur rarely in pancreatic tumors which is thought to occur in less than 0.5% of cases. Lynn Matrisian, chief science officer at the Pancreatic Cancer Action Network (PanCAN) says that “It’s encouraging to see pharmaceutical companies and the FDA moving in the direction of more personalized treatments for patients based on their tumor’s biology instead of simply its location in the body.”
– Arpitha Shetty,