New Treatment in Development for Mastocytosis

Many cancer and blood specialists will not have encountered systemic mastocytosis. A new drug targets the underlying defect of the disease and will help put doctors on the lookout. Keep reading below to learn more about this development, or follow the original story here.

Dr. DeAngelo presented clinical data for a new drug agent at the annual meeting of the American Society of Hematology in 2017. The agent, known as avapritinib targets a specific mutation which occurs in 90% of mastocytosis cases.

Results from an early trial show impressive results. Activity is high, and disease control was observed in all patients. Improvements in clinical symptoms also occurred rapidly.

Dr. DeAngelo believes “once you have a therapy, patients will come.” He continues to explain that once an effective therapy is available, mastocytosis is a disease not to be overlooked.

Dr. DeAngelo also mentioned that the amount of attention given to mastocytosis is already increasing. Last year, the FDA approved a new drug for mastocytosis called midostaurin

When Dr. DeAngelo began taking an interest in mastocytosis he only saw one or two cases each year. Now he receives one to two each week.

Current estimates show that 2000 cases of mastocytosis occur in the US each year. Dr. DeAngelo, on the other hand, suggests this is a low estimate and mentions how often the disease is missed.

In today’s medicine, the most common way a mastocytosis patient reaches a hematologist is by referral from a dermatologist. This is usually as a result of skin lesions. Occasionally allergists or immunologists pickup on a patient who presents with recurring anaphylactic reactions. In both cases, symptoms could be signs of mast cells over producing as part of a pathology.

Mast cells typically account for a few cells in every 1000. In a patient with mastocytosis, however, bone marrow may be flooded with mast cells at rates of 10-50%.

Uncontrolled growth of mast cells often leads to distorted organs. In these cases, the spleen is swollen, leaving almost no room for the stomach. Mast cells may also build up in the small intestine and colon leading to malnutrition and loss of weight. In other cases, mast cells lead to impaired liver function and low blood counts. Sometimes mast cells even develop into a form of leukemia.

Until the approval of midostaurin last year there was no treatment for mastocytosis.

Other forms of therapy were limited and rarely successful. Even midostaurin sits only a step above though. The new results from avaprinitib are too early to call in full confidence, but have been markedly improved. In a small phase 1 study consisting of 18 evaluable patients, 72% experience an overall response, and every member of the group had their disease controlled.

A phase 2 trial will test the drug on a larger number of patients. Success in the trial would mark a giant leap forward in the study and treatment of mastocytosis. The Secretary of the American Society of Hematology remarked that such a developmental leap would be something of a legend. He compared the new study to one 20 years ago in which new drugs had been discovered for the treatment of chronic myeloid leukemia.

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