Hizentra (Subcutaneous Immunoglobulin) for Mast Cell Activation Syndrome (MCAS)
Hizentra (subcutaneous immunoglobulin) is not recommended as a treatment for Mast Cell Activation Syndrome (MCAS) based on current guidelines and evidence. 1, 2
First-Line Treatment Options for MCAS
The management of MCAS focuses on mediator-targeted therapies rather than immunoglobulin replacement:
H1 antihistamines: Nonsedating options like fexofenadine and cetirizine are preferred first-line treatments, often used at 2-4 times standard doses for dermatologic symptoms, flushing, pruritus, tachycardia, and abdominal discomfort 1
H2 antihistamines: Ranitidine, famotidine, or cimetidine are recommended for gastrointestinal symptoms and to help H1 antihistamines attenuate cardiovascular symptoms 1
Oral cromolyn sodium: Effective for gastrointestinal symptoms (bloating, diarrhea, cramps) with potential benefits for neuropsychiatric manifestations; should be started at low doses and gradually increased to 200mg four times daily 1, 2
Second-Line Treatment Options
For patients with inadequate response to first-line therapies:
Leukotriene modifiers: Montelukast, zafirlukast, or zileuton may help with dermatologic and respiratory symptoms, particularly when used with H1 antihistamines 1, 3
Aspirin: May reduce flushing and hypotension in patients with elevated urinary 11β-PGF2α levels, but should be introduced cautiously in a controlled setting due to risk of triggering mast cell degranulation 1
Doxepin: A potent H1 and H2 antihistamine with tricyclic antidepressant activity that may reduce central nervous system manifestations, though sedation and cognitive effects are concerns, particularly in elderly patients 1
Advanced Treatment Options for Refractory MCAS
Omalizumab: Anti-IgE therapy has shown efficacy in preventing anaphylactic episodes in case reports and case series of MCAS patients resistant to mediator-targeted therapies 1, 4
Corticosteroids: Short-term steroid bursts may be useful for refractory symptoms at an initial oral dose of 0.5 mg/kg/day with slow taper over 1-3 months 1, 2
Tyrosine kinase inhibitors: For clonal MCAS with severe symptoms refractory to conventional therapy, agents like midostaurin may be considered, though with careful monitoring for toxicity 1, 2
Acute Management of MCAS Episodes
Epinephrine: Patients with history of systemic anaphylaxis should carry an autoinjector and be trained in its use 1
Supine positioning: Critical during hypotensive episodes 1, 2
Albuterol: Can be administered via nebulizer or metered-dose inhaler for bronchospasm 1, 2
Important Considerations and Pitfalls
Avoid sedating antihistamines in elderly: First-generation H1 antihistamines and those with anticholinergic effects can cause cognitive decline, particularly in elderly patients 1
Medication trials should be conducted cautiously: Introduce new medications in a controlled setting with emergency equipment available 2, 5
Treatment response assessment: Improvement in symptoms correlated with specific mediator elevations is necessary for MCAS diagnosis and treatment evaluation 1, 5
Trigger identification and avoidance: A crucial component of management 2, 5
Conclusion on Hizentra for MCAS
While immunoglobulin therapy (including Hizentra) has established roles in various immunodeficiency and autoimmune conditions, it is not included in any current guidelines or evidence-based recommendations for MCAS treatment 1, 2. The treatment algorithm for MCAS focuses on mediator-blocking agents, mast cell stabilizers, and in severe cases, medications that reduce mast cell numbers or activation potential 5, 6.