Avapritinib is in clinical development for the treatment of advanced systemic mastocytosis (SM) in adults. SM is a condition where mast cells grow uncontrollably and accumulate in body organs/tissues such as the skin, internal organs, lymph nodes and bones. Mast cells are immune cells that release inflammatory mediators that are important in the body’s allergic responses. When mast cells are present in large numbers there is a high release of these mediators leading to symptoms such as itching, fever, abdominal pain, nausea and vomiting. In advanced SM, mast cells collect in such high quantities that they lead to organ damage and dysfunction, bone fractures and anaemia.
Avapritinib, formulated for oral administration, works by selectively blocking the active form of the KIT protein kinase. More than 90% of SM cases are due to a KIT D816V mutation that results in KIT being constantly active. In its active state, KIT triggers a series of downstream signals resulting in the accumulation of mast cells and uncontrolled release of inflammatory mediators. By blocking KIT, avapritinib will reduce the accumulation and uncontrolled activation of mast cells. If licenced, avapritinib will offer an additional treatment option for patients with advanced SM.
Anifrolumab is a drug designed to specifically block type I IFN signalling by binding to part of the type I IFN receptor and therefore preventing activity of all IFNs that are involved in the inflammatory pathway. If licensed, anifrolumab will offer an add-on treatment option for patients with moderately to severely active SLE.