Methotrexate is a commonly used chemotherapy drug employed to treat osteosarcoma, a bone cancer. Unfortunately, one side effect of traditional chemotherapy is the potential to harm perfectly healthy cells in the process of destroying cancerous ones. Researchers from Washington University in St. Louis think they are on their way to a solution to this problem with a new bone cancer treatment that uses two drugs to target the energy sources of cancerous tumors. 

The newly-developed therapy starts with a drug called NCT-503, which is part of a category of drugs that offers metabolic therapies for cancer. These experimental therapies go after the chemical reactions that allow cancerous cells to sustain themselves. Specifically, NCT-503 inhibits the production of amino acid serine, which allows cancerous cells to multiply, essentially stopping the tumor from growing. 

Once the cells stop multiplying, they usually turn to alternative energy sources by burning metabolic build-up using a molecule called mTORC1. This is where the second drug comes in. A mTORC1 inhibitor blocks this function, denying the cells of energy completely so they eventually die off. 

In experiments, the two-drug method has been successful in slowing the growth of cancerous tumors. Although the method is not yet ready for human trials, it does offer the potential for chemotherapy-free cancer treatments in the future. Even if the two-drug method cannot eliminate cancer cells altogether, it could vastly reduce the concentration and frequency of chemotherapy treatments for less detrimental effects on healthy cells and less invasive treatments for patients.