NCCN Publishes Guidelines for Systemic Mastocytosis

“Mastocytosis — just the mention of it on rounds makes most medical trainees shudder,” says Aaron Gerds, MD, MS, of Cleveland Clinic’s Department of Hematology and Medical Oncology. “Not only is it a rare hematologic disease, affecting about one in 10,000 people, it’s also not simple. There are various clinical phenotypes that require not-so-common tests to diagnose.”

Because mast cells can accumulate anywhere in the body, there’s a wide spectrum of mastocytosis manifestations. In cutaneous mastocytosis, seen often by allergists, care centers around treating histamine-related symptoms. The clone rarely becomes more aggressive. However, the clone in systemic mastocytosis (SM) can be more pugnacious, attacking various organs and in some cases causing mortality in a short period of time.

To aid in the care of patients, the National Comprehensive Cancer Network (NCCN) recently introduced the first NCCN Guidelines® for SM. The opinion-based recommendations were developed by a multidisciplinary panel of experts, including hematologists, medical oncologists and allergists.

While European guidelines first set standards for managing SM in 2013, there have been no U.S. guidelines until now.

Why now?

“Mastocytosis used to fall under the broader category of myeloproliferative neoplasms (MPN),” says Dr. Gerds, who chaired the NCCN panel that developed the new U.S. guidelines. “But in 2016, the World Health Organization moved mastocytosis out of MPN and into its own disease category. The new guidelines were born of that change.”

In addition, in April 2017, the U.S. Food and Drug Administration (FDA) granted the first approval of a drug (midostaurin) for the treatment of SM. Now a second drug, avapritinib, is showing remarkable responses in early clinical trials and may move quickly through the FDA approval process, says Dr. Gerds.

“Both of these drugs have hit the scene since the European guidelines came out,” he says. “It’s the right time to publish updated, U.S.-specific guidelines that can help clinicians diagnose, risk stratify and recommend sequential treatment.”

Familiar format, new recommendations

The new guidelines include a diagnostic algorithm and recommended workups for patients with signs or symptoms of SM (e.g., anaphylaxis, flushing, itching, hives, swelling, nasal congestion, wheezing) — as well as indicators of five levels of the disease:

1. Indolent SM.
2. Smoldering SM.
3. Aggressive SM.
4. SM with an associated hematologic neoplasm.
5. Mast cell leukemia.

Treatment is outlined by disease level as well as by organ involvement and symptoms.

“Most oncology clinicians are familiar with NCCN guidelines,” says Dr. Gerds. “They’re presented in a consistent, easy-to-follow format, so even if clinicians encounter SM only once a year, they can feel comfortable and confident about accessing the information they need.”

NCCN guidelines on SM are ready and available when clinicians need them, he says.

Ensuring safe, effective treatment

Ideally, patients with SM should be treated in a high-volume center by specialists familiar with the disease, notes Dr. Gerds. But the new NCCN guidelines offer a starting point for clinicians to counsel patients and begin treatment if indicated, possibly in collaboration with a referral center.

“Most importantly, these guidelines will help physicians prescribe medications in a more consistent manner,” says Dr. Gerds. “More uniformity in management of SM will ensure safe, effective treatments for patients.”