(PROSPECTOR) Screening Study Evaluating the Prevalence of the KIT D816V Mutation in Patients With Systemic Mast Cell Activation

Study Evaluating the Prevalence of the KIT D816V Mutation in Peripheral Blood of Patients With Evidence of Systemic Mast Cell Activation (MCA)

This is a multi-center screening study with the primary objective to determine the prevalence of KIT D816V mutation in peripheral blood in patients with evidence of systemic mast cell activation (MCA).

Inclusion Criteria:

• Presenting with at least one of the three criteria below as evidence of systemic mast cell activation:

  1. Involvement of 2 or more organ systems, characterized by skin (pruritus, urticaria, flushing and angioedema), cardiovascular (tachycardia, syncope, and hypotension), gastrointestinal (diarrhea, nausea, vomiting, and gastrointestinal cramping) or respiratory/naso-ocular (wheezing, conjunctival injection, and nasal stuffiness) AND serum basal tryptase levels ≥8 ng/ml. One of the organ systems must be the cardiovascular system.
  2. Severe anaphylaxis (Ring and Messmer grading ≥II) due to Hymenoptera sting, regardless of serum basal tryptase levels.
  3. Severe anaphylaxis (Ring and Messmer grading ≥II), with cardiovascular involvement and documented event-related tryptase elevation fitting the formula 20% of baseline plus 2 ng/ml evaluated in at least 1 event.

Exclusion Criteria:

• Patient previously diagnosed with any of the following WHO systemic mastocytosis (SM) sub-classifications: mastocytosis in the skin, indolent SM, smoldering SM, SM with associated hematological neoplasm, aggressive SM, mast cell leukemia, mast cell sarcoma