Medroxyprogesterone - valproic acid - aspirin. MVA regime to reduce transfusion associated mortality in late-term hemoglobinopathies. Hypothesis and rationale

Abstract

Medroxyprogesterone acetate (MPA) - a safe depot contraceptive - is shown previously to reduce painful crises of sickle cell anemia, which is parallel with the recent findings showing progesterone induction of fetal hemoglobin genes. This would be a way to reduce transfusions for late term thalassemia major and sickle cell-disease cases with no chances left for a stem cell transplantation. In these patients, transfusional hemosiderosis causes irreversible damage to many organs despite the available iron-chelating agents. Pharmacological strategies either target the conformal structure of the defective adult hemoglobin or aim to activate fetal hemoglobin concentrations. The only concern on MPA may be its thromboembotic risks, which may be uncoupled with agents acting both anticoagulant and inductive on the blood oxygen-carrying affinity. Such agents could be valproic acid and aspirin. Valproic acid is being safety used to treat epilepsy and its histone acetylating function may lead its induction of fetal hemoglobin. Aspirin was shown to increase oxygen affinity of hemoglobin via acetylating lysine residues and its general acetylating activity on proteins such as histones makes it also an interesting candidate to activate fetal hemoglobin. We propose that combining MPA with clinically available doses of valproic acid and aspirin would be beneficial in terms of both reduced coagulation risks and increased oxygen affinity to decrease the transfusions and to improve the prognosis in tate-phase hemoglobin disorders. (C) 2006 Elsevier Ltd. All rights reserved.