Cladribine therapy for systemic mastocytosis.

Area of Science:

• Hematology
• Oncology
• Pharmacology

Background:

• Systemic mastocytosis (SM) presents with debilitating symptoms due to mast cell mediator release or infiltration.
• Current treatments for SM lack curative potential, highlighting the need for effective therapeutic options.
• Previous case reports suggested cladribine efficacy in managing SM.

Purpose of the Study:

• To evaluate the efficacy and safety of cladribine as a single-agent treatment for severe systemic mastocytosis.
• To assess the impact of cladribine on clinical signs, symptoms, and mast cell parameters in SM patients.

Main Methods:

• A pilot study involving ten patients with severe systemic mastocytosis.
• Treatment consisted of cladribine infusions (0.10-0.13 mg/kg) over five days, repeated every 4-8 weeks for up to six cycles.
• Patients were monitored for clinical response, serum tryptase levels, and urinary histamine metabolite excretion.

Main Results:

• All ten patients showed improvement in signs, symptoms, and mast cell parameters.
• Nine patients completed six cycles; one discontinued due to toxicodermia.
• No complete remission was achieved, but responses were ongoing in most patients, with one relapse and subsequent re-response.

Conclusions:

• Single-agent cladribine demonstrates effectiveness and relative safety for severe systemic mastocytosis.
• The treatment significantly alleviates symptoms and reduces mast cell activity markers.
• Further research is needed to optimize cladribine dosage and scheduling for SM treatment.