title: Prophylactic therapy with enoxaparin in children with acute lymphoblastic leukemia and inherited thrombophilia during L-asparaginase treatment.
abstract: BACKGROUND
  Thrombotic events (TE) are well documented in patients with acute lymphoblastic leukemia (ALL). They occur due to a combination of disease, host and treatment-related risk factors. Low molecular weight heparin (LMWH) has been found to be effective and safe in children with ALL during L-asparaginase treatment. At present, whether or not to give primary anticoagulant prophylaxis for TE during induction or reinduction courses to children with ALL is controversial. Our group investigated the use of LMWH as a prophylactic treatment for ALL children with a genetic prothrombotic predisposition.
  
  
  METHODS
  Eighty consecutive children with ALL treated between the years 1999 and 2008 were studied. Genetic analysis of factor V Leiden (G1691A) and prothrombin (G20210A) gene mutations were done at diagnosis. LMWH was given once daily subcutaneously at a dose of 1mg/kg, starting with the first dose of L-asparaginase (day 12 of induction, day 8 of consolidation) until one week after the last dose (day 40 of induction, day 25 of consolidation), to patients with inherited thrombophilia stemming from either factor V Leiden or prothrombin gene mutation.
  
  
  RESULTS
  Eighteen patients were found to have a genetic predisposition for TE, all of them received prophylactic LMWH. Six of the 80 (7.5%) patients developed thromboembolic events. Three of these six had a prothrombin (PT) gene mutation and received prophylactic LMWH. No TE event occurred in patients with factor V Leiden mutation receiving prophylactic LMWH.
  
  
  CONCLUSIONS
  It is suggested that patients with ALL and PT gene mutation may have a higher risk of clotting complications in comparison to patients with factor V Leiden mutation. A randomized trial of LMWH should be performed to assess its safety and efficacy in preventing venous TE.
authors.affiliation: Department of Pediatric Hematology Oncology, Meyer Children's Hospital, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Dan
authors.initials: D
authors.lastname: Harlev
authors.forename: Irina
authors.initials: I
authors.lastname: Zaidman
authors.forename: Galit
authors.initials: G
authors.lastname: Sarig
authors.forename: Myriam Weyl
authors.initials: MW
authors.lastname: Ben Arush
authors.forename: Benjamin
authors.initials: B
authors.lastname: Brenner
authors.forename: Ronit
authors.initials: R
authors.lastname: Elhasid
mesh_terms: D000293:Adolescent; D000925:Anticoagulants / Q000627:therapeutic use*; D001215:Asparaginase / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D017984:Enoxaparin / Q000627:therapeutic use*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007223:Infant; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000150:complications* / Q000188:drug therapy; D012189:Retrospective Studies; D019851:Thrombophilia / Q000150:complications / Q000235:genetics* / Q000517:prevention & control*
chemical_list: D000925:Anticoagulants; D017984:Enoxaparin; D001215:Asparaginase