Interest of interferon alpha in systemic mastocytosis. The French experience and review of the literature

Systemic mastocytosis (SM) are defined by an abnormal growth and accumulation of mast cells in bone marrow and/or other extracutaneous organs. There is currently no cure for this disease. Because of similarities and/or association of mastocytosis with myeloproliferative disorders, interferon alpha has been tested but with contradictory reported results. A first prospective multicenter phase II trial was then started in France. From 1994 to 1997, 20 adult patients with confirmed bone marrow involvement received interferon α-2b for at least 6 months, (from 1 million U per day up to 5 million U/m 2/day). Thirteen patients who presented systemic and/or specific cutaneous manifestations, demonstrated objective responses: seven (35%) were partial, six (30%) minor but no complete response could be observed at the time of analysis. The bone marrow remained unchanged in 12/13. Thus, interferon should be offered to patients with severe systemic manifestations, who have not responded to symptomatic therapies, even in case of non-aggressive mastocytosis, with or without corticosteroids the first weeks. Long-term therapy should be offered to patients with initial positive response. To control more aggressive SM or mastocytosis associated with clonal hematologic non-mast cell lineage or leukaemia mast cell, other chemotherapeutic regimens should be proposed like Cladribine (2-chlorodeoxyadenosine, 2-CDA) or polychemotherapies including interferon as it is being tested in France in a new multicentric protocol, coordinated by the association AFIRMM, with interferon and oral cytarabine. Introduction. – Les mastocytoses systémiques sont caractérisées par une prolifération anormale de mastocytes au sein de plusieurs organes et en particulier de la moelle osseuse. Les similitudes de cette affection avec un syndrome myéloprolifératif et l'association possible de ces deux types de proliférations clonales ont motivé l'introduction de l'interféron dans le traitement des mastocytoses systémiques, considérées jusqu'à présent comme des affections incurables. Patients et méthodes. – Vingt patients adultes répondant aux critères de mastocytose systémique ont été inclus dans une étude prospective multicentrique de phase II de 1994 à 1997. Chacun des patients étudiés a reçu pendant six mois au minimum un traitement d'interféron alpha 2b à des doses progressives comprises entre 1 et 5 millions d'unités/m 2 par jour. Résultats. – Une réponse objective a été enregistrée chez 13 patients. A