What changed: Systemic mastocytosis

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H1 and H2 antihistamines, cromolyn, leukotriene antagonists, omalizumab for anaphylaxis, epinephrine autoinjector, bone protection; avapritinib 25 mg daily for moderate to severe symptoms uncontrolled by these (PIONEER). (NCCN Category 2A)

PIONEER; FDA approval May 2023, the first therapy for the indolent form.

Advanced systemic mastocytosis

Avapritinib 200 mg daily (platelets above 50 x 10^9/L) as preferred agent; midostaurin as alternative or where platelets are low. (NCCN Category 2A (preferred: avapritinib))

Overall response rate 75 percent and complete remission rate 36 percent in 53 evaluable patients with advanced systemic mastocytosis; maximum tolerated dose not reached; recommended dose 200 mg daily; approved June 2021.

EXPLORER and PATHFINDER; FDA approval June 2021.

Newly diagnosed FLT3-mutated AML with 7+3 and consolidation; advanced systemic mastocytosis

Gotlib and colleagues (NEJM 2016); FDA approval April 2017.

Valent criteria; imatinib found inactive against D816V.

Nagata and colleagues (1995) confirm the activating mutation in most patients.

Ellis reports mast cell infiltration of internal organs at autopsy.

Nettleship and Tay describe the skin lesions; Unna links them to mast cells in 1887.