The National Institute for Health and Care Excellence (NICE) has recommended Blueprint Medicines’ Ayvakyt (avapritinib) to treat patients with the rare blood disorder systemic mastocytosis (SM).
The drug can now be used as a monotherapy to treat patients in England and Wales with the three subtypes of advanced SM: aggressive SM (ASM), SM with an associated haematological neoplasm (SM-AHN) or mast cell leukaemia (MCL).
Approximately one in 10,000 people in the UK are thought to be living with SM, with advanced SM accounting for up to 10% of cases.
The disease is caused by the abnormal buildup of mast cells, a key part of the body’s immune system, and leads to symptoms including skin lesions, diarrhoea, bone pain, fatigue and anaphylaxis.
Historically, the median overall survival has been around 3.5 years in ASM, two years in SM-AHN and less than six months in MCL.
Blueprint’s Ayvakyt works by targeting KIT D816V, the primary underlying cause of the disease, and has been shown to lead to complete remission in a subset of AdvSM patients.
NICE’s final draft guidance, which follows the Medicines and Healthcare products Regulatory Agency’s approval of the drug in September, was based on positive results from the phase 2 PATHFINDER trial.
Overall response rate (ORR) for advanced SM patients receiving Ayvakyt was 68% after a median follow-up of 14.3 months, where ORR was defined as complete response with full or partial recovery of peripheral blood counts (CR+CRh), partial response or clinical improvement, and the CR+CRh rate was 18%.
Data from the early-stage EXPLORER trial also supported the health technology assessment agency’s decision.
PATHFINDER and EXPLORER trial investigator Deepti Radia, a consultant haematologist at Guy’s and St Thomas’ NHS Foundation Trust, said: “Traditionally, patients with ASM, SM-AHN and MCL have faced a poor prognosis, with limited treatment options to address the life-threatening organ damage associated with the disease.
“In clinical studies, the majority of evaluable patients responded to treatment with [Ayvakyt], with a subset achieving complete remissions with full or partial haematologic recovery.”
