title: Response to steroids predicts response to rituximab in pediatric chronic immune thrombocytopenia.
abstract: BACKGROUND
  Treatment choice in pediatric immune thrombocytopenia (ITP) is arbitrary, because few studies are powered to identify predictors of therapy response. Increasingly, rituximab is becoming a treatment of choice in those refractory to other therapies.
  
  
  METHODS
  The objective of this study was to evaluate univariate and multivariable predictors of platelet count response to rituximab. After local IRB approval, 565 patients with chronic ITP enrolled and met criteria for this study in the longitudinal, North American Chronic ITP Registry (NACIR) between January 2004 and October 2010. Treatment response was defined as a post-treatment platelet count ≥ 50,000/µl within 16 weeks of rituximab and 14 days of steroids. Treatment response data were captured both retrospectively at enrollment and then prospectively.
  
  
  RESULTS
  Eighty (14.2%) patients were treated with rituximab with an overall response rate of 63.8% (51/80). Univariate correlates of response to rituximab included the presence of secondary ITP and a positive response to steroids. In multivariable analysis, response to steroids remained a strong correlate of response to rituximab, OR 6.8 (95% CI 2.0-23.0, P = 0.002). Secondary ITP also remained a strong predictor of response to rituximab, OR 5.6 (95% CI 1.1-28.6, P = 0.04). Although 87.5% of patients who responded to steroids responded to rituximab, 48% with a negative response to steroids did respond to rituximab.
  
  
  CONCLUSIONS
  In the NACIR, response to steroids and presence of secondary ITP were strong correlates of response to rituximab, a finding not previously reported in children or adults.
authors.affiliation: Children's Hospital Boston, Boston, MA, USA. rachael.grace@childrens.harvard.edu
authors.forename: Rachael F
authors.initials: RF
authors.lastname: Grace
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Bennett
authors.forename: A Kim
authors.initials: AK
authors.lastname: Ritchey
authors.forename: Michael
authors.initials: M
authors.lastname: Jeng
authors.forename: Courtney D
authors.initials: CD
authors.lastname: Thornburg
authors.forename: Michele P
authors.initials: MP
authors.lastname: Lambert
authors.forename: Michelle
authors.initials: M
authors.lastname: Neier
authors.forename: Michael
authors.initials: M
authors.lastname: Recht
authors.forename: Manjusha
authors.initials: M
authors.lastname: Kumar
authors.forename: Victor
authors.initials: V
authors.lastname: Blanchette
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Klaassen
authors.forename: George R
authors.initials: GR
authors.lastname: Buchanan
authors.forename: Margaret Heisel
authors.initials: MH
authors.lastname: Kurth
authors.forename: Diane J
authors.initials: DJ
authors.lastname: Nugent
authors.forename: Alexis A
authors.initials: AA
authors.lastname: Thompson
authors.forename: Kimo
authors.initials: K
authors.lastname: Stine
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Kalish
authors.forename: Ellis J
authors.initials: EJ
authors.lastname: Neufeld
mesh_terms: D000293:Adolescent; D058846:Antibodies, Monoclonal, Murine-Derived / Q000627:therapeutic use*; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000627:therapeutic use; D007155:Immunologic Factors / Q000627:therapeutic use; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D010976:Platelet Count; D011241:Prednisone / Q000627:therapeutic use*; D011446:Prospective Studies; D012189:Retrospective Studies; D000069283:Rituximab; D013921:Thrombocytopenia / Q000188:drug therapy* / Q000276:immunology*; D016896:Treatment Outcome
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000970:Antineoplastic Agents; D005938:Glucocorticoids; D016756:Immunoglobulins, Intravenous; D007155:Immunologic Factors; D000069283:Rituximab; D011241:Prednisone