Leukemia is a type of cancer that is formed in the blood or the bone marrow. Blood cells, mainly white blood cells, are formed in the bone marrow. The cancer most commonly begins in new white blood cells, which are called lymphocytes. This is only one of the types of this cancer, called lymphocytic leukemia. There are three other types of leukemia: acute, chronic, and myelogenous. This cancer is caused by DNA damage in the blood cells, which ultimately leads to the rapid and uncontrollable growth and division of cells. It is the most common type of cancer in kids 15 and under, although leukemia is seen mostly in adults above the age of 55.
A common path of treatment for a leukemic patient is chemotherapy. Leukemia chemotherapy specifically has a component called asparaginase. Asparaginase is an enzyme that is isolated from the bacteria E. coli. It is a common treatment for leukemia because it can inhibit the G1 phase of the cell cycle, stop protein synthesis, and cause apoptosis (cell death) in leukemic blood cells by breaking a certain bond in the body (between L-asparagine to L-aspartic acid and ammonia). This enzyme is given as an injection into a large muscle, and it is given in one or two doses. Dosage depends on factors such as the patient’s height and weight. It can also be injected into a vein as an infusion.
One of the problems with this treatment is that 20% of patients develop an allergy to asparaginase derived from E. coli. Luckily, Jazz Pharmaceuticals’ Rylaze recently got approved by the FDA. Rylaze is an asparaginase that comes from Erwinia chrysanthemi, a plant pathogen. It is currently intended to be used for lymphocytic and acute lymphocytic leukemia. Previously, this same company created a similar asparaginase called Erwinaze. Since 2016, there have been manufacturing problems and shortages, so it was not a reliable alternative to E. coli asparaginase. Rylaze was developed and then tested in Study JZP 458-201. 102 patients averaging 10 years old received it at varying doses, as they were allergic to the original treatment. 94% of patients reached asparaginase target activity. Although this study is very promising, there are some risks associated. Blood clots, hemorrhaging, and fetal harm have been observed side effects. However, the approval became official on June 30 2021, and Rylaze will be available in the middle of July. Hopefully, it will prove to be a safe treatment for leukemic patients who are unable to receive the traditional asparaginase in their chemotherapy.