The Food and Drug Administration (FDA) has approved Ayvakit (avapritinib) for the treatment of adults with advanced systemic mastocytosis, including patients with aggressive systemic mastocytosis, systemic mastocytosis with an associated hematological neoplasm, and mast cell leukemia.

The approval was based on data from 2 multicenter, single-arm, open-label clinical trials, EXPLORER (ClinicalTrials.gov Identifier: NCT02561988) and PATHFINDER (ClinicalTrials.gov Identifier: NCT03580655). The efficacy of avapritinib in the treatment of advanced systemic mastocytosis was based on overall response rate (ORR) in 53 patients dosed at up to 200mg daily per modified IWG-MRT-ECNM criteria as adjudicated by the central committee. The median duration of follow up for these patients was 11.6 months (95{d847ba2f23daf15c773bda6cb71ac33aa9166b9578a171d654c6e3c528a0b6bc} CI, 9.9-16.3).

Combined results from both trials showed an ORR of 57{d847ba2f23daf15c773bda6cb71ac33aa9166b9578a171d654c6e3c528a0b6bc} (95{d847ba2f23daf15c773bda6cb71ac33aa9166b9578a171d654c6e3c528a0b6bc} CI, 42-70), with 28{d847ba2f23daf15c773bda6cb71ac33aa9166b9578a171d654c6e3c528a0b6bc} of patients achieving complete remission with full or partial hematologic recovery and 28{d847ba2f23daf15c773bda6cb71ac33aa9166b9578a171d654c6e3c528a0b6bc} having partial remission. The median duration of response was 38.3 months (95{d847ba2f23daf15c773bda6cb71ac33aa9166b9578a171d654c6e3c528a0b6bc} CI, 19-not estimable) and the median time to response was 2.1 months. The most common adverse reactions reported included edema, diarrhea, nausea, and fatigue/asthenia.

Treatment with Ayvakit is associated with a risk of intracranial hemorrhage, cognitive effects, and embryo-fetal toxicity. Ayvakit is not recommended for the treatment of patients with advanced systemic mastocytosis with platelet counts of less than 50 x 109/L.


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Ayvakit, a tyrosine kinase inhibitor, is already indicated for the treatment of adults with unresectable or metastatic gastrointestinal stromal tumor harboring a platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutation, including PDGFRA D842V mutations.

The product is supplied as 100mg, 200mg, and 300mg tablets in 30-count bottles.

References

  1. FDA approves avapritinib for advanced systemic mastocytosis. [press release]. Silver Spring, MD: US Food and Drug Administration; June 16, 2021. 
  2. FDA approves Blueprint Medicines’ Ayvakit (avapritinib) for the treatment of adults with advanced systemic mastocytosis. [press release]. Cambridge, MA: Blueprint Medicines Corporation; June 16, 2021.
  3. Ayvakit [package insert]. Cambridge, MA: Blueprint Medicines Corporation; 2021.

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