What is the treatment for Mast Cell Activation Syndrome (MCAS)?

From the Guidelines

The treatment for Mast Cell Activation Syndrome (MCAS) typically involves a multi-faceted approach targeting symptom control and mast cell stabilization, with first-line treatments including H1 antihistamines, H2 antihistamines, and mast cell stabilizers, as recommended by the most recent guidelines 1.

Key Treatment Components

• H1 antihistamines such as cetirizine (10mg daily), loratadine (10mg daily), or fexofenadine (180mg daily) are often used at 2 to 4 times the standard dose to relieve symptoms caused by secreted histamine 1
• H2 antihistamines like famotidine (20mg twice daily) or ranitidine (150mg twice daily) can be used as first-line therapy for gastrointestinal symptoms and might help H1R antihistamines attenuate cardiovascular symptoms 1
• Mast cell stabilizers such as oral cromolyn sodium (200mg 3-4 times daily before meals) or ketotifen (1-2mg twice daily) are often added to prevent mast cell degranulation 1

Additional Treatment Options

• Leukotriene modifiers like montelukast (10mg daily) can be used for breakthrough symptoms 1
• Low-dose corticosteroids such as prednisone (5-10mg daily) may be prescribed for short periods in severe cases 1
• Non-pharmacological approaches, including identifying and avoiding personal triggers, maintaining a low-histamine diet, and gradual desensitization to unavoidable triggers, are equally important 1

Personalized Treatment Approach

• Treatment effectiveness varies significantly between individuals, so therapy must be personalized through careful monitoring and adjustment 1
• The goal of treatment is to reduce the inappropriate mast cell activation that causes the release of histamine and other inflammatory mediators responsible for symptoms like flushing, itching, gastrointestinal issues, and cardiovascular problems 1

From the FDA Drug Label

Clinical Pharmacology In vitro and in vivo animal studies have shown that cromolyn sodium inhibits sensitized mast cell degranulation which occurs after exposure to specific antigens. Cromolyn sodium acts by inhibiting the release of mediators from mast cells. The treatment for Mast Cell Activation Syndrome (MCAS) may include cromolyn sodium as it inhibits mast cell degranulation and the release of mediators from mast cells 2.

• Key points about cromolyn sodium:
  • Inhibits sensitized mast cell degranulation
  • Inhibits the release of mediators from mast cells
  • No intrinsic bronchodilator or antihistamine activity It is essential to note that while cromolyn sodium may be used in the treatment of MCAS, the provided information is limited to its mechanism of action and pharmacology.

From the Research

Treatment for Mast Cell Activation Syndrome (MCAS)

The treatment for MCAS typically involves a combination of medications and therapies aimed at stabilizing mast cells, reducing inflammation, and managing symptoms. Some of the treatment options include:

• Medications such as histamine receptor blockers, anti-mediator-type drugs, and MC-targeting therapy 3
• Continuous diphenhydramine infusion, which has been shown to improve anaphylactic reactions and decrease hospital readmission in patients with severe MCAS 4
• Imatinib, which has been used to treat patients with KIT-D816V-negative MCAS, and has led to further improvement of quality of life 4
• Tofacitinib, a JAK1/JAK3 inhibitor, which has been shown to be effective in treating MCAS by targeting downstream inflammatory effects 5
• IgE-blocking antibodies, which may be used in combination with other treatments for patients with severe MCAS and IgE-dependent allergies 3

Diagnostic Criteria and Treatment Response

The diagnosis of MCAS is based on three criteria:

• The presence of typical symptoms
• Elevation of serum tryptase levels
• Response to anti-mediator treatment 6 Patients with MCAS may respond to treatment with a decrease in symptoms and an improvement in quality of life. The treatment response can be used to guide further management and adjustment of medications as needed 7, 6

Classification and Management of MCAS

MCAS can be classified into different subtypes, including primary MCAS, secondary MCAS, and idiopathic MCAS 3. The management of MCAS requires a personalized approach, taking into account the underlying etiology, comorbidities, and individual patient needs. A thorough medical evaluation is necessary to establish the diagnosis and develop an optimal management plan for MCAS, following the principles of personalized medicine 3, 7