Vaccine Response After Rituximab for Chronic, Severe Idiopathic Thrombocytopenic Purpura
Condition: Idiopathic Thrombocytopenic Purpura; Immune Thrombocytopenic Purpura
MeSH terms: Purpura; Purpura, Thrombocytopenic; Purpura, Thrombocytopenic, Idiopathic
Study type: Interventional

Summary: 
      The purpose of this study is to determine how children with a history of severe, chronic
      Idiopathic Thrombocytopenic Purpura (ITP) who were treated with rituximab might respond to
      vaccines. Eligible patients are previously or currently enrolled in a study entitled "Open
      Label, Phase I/II Trial of Rituximab for Chronic, Severe Idiopathic Thrombocytopenic Purpura
      in Children and Adolescents" and have decided to obtain an inactivated influenza vaccination.
      These patients will be invited to provide one blood sample prior to vaccination and a second
      sample following vaccination to quantify immune response to vaccination.
    

Detailed description: 
      The purpose of this ancillary, pilot-phase study is to determine how children with a history
      of severe, chronic ITP who were treated with rituximab might respond to vaccines. Eligible
      patients are previously or currently enrolled in a study entitled "Open Label, Phase I/II
      Trial of Rituximab for Chronic, Severe Idiopathic Thrombocytopenic Purpura in Children and
      Adolescents" (CHB 02-12-160) and have decided to obtain the trivalent, inactivated influenza
      vaccination. These patients will be invited to provide one blood sample prior to vaccination
      and a second sample 4-8 weeks after vaccination to quantify immune response to vaccination.
      Additionally, if patients are scheduled to receive a tetanus booster vaccination within one
      month before or after the influenza vaccination, response to tetanus will also be quantified.
      This sample will be collected during the same phlebotomy as the influenza sample. In some
      cases, a blood sample was stored prior to rituximab treatment and will be used for baseline
      assessment. The primary and secondary objectives for this study are as follows:

      Primary:

        -  To determine the portion of patients who will respond adequately to influenza
           vaccination, with adequacy defined as a titer greater than 1:32 for each strain of virus
           in the vaccine, measured 4-8 weeks after administration of the vaccine OR greater than a
           four-fold increase in titers measured 4-8 weeks after administration of the vaccine

      Secondary Objectives:

        -  To evaluate the ability to mount a response to the influenza vaccine, with response
           defined as any increase in influenza antibody titer for each strain of virus between
           samples before and 4-8 weeks after vaccination.

        -  To evaluate the ability to mount an adequate response to tetanus toxoid, with adequacy
           defined as in the primary objective.

        -  To evaluate the ability to mount a response to tetanus toxoid, with response defined as
           above.

        -  To compare response to influenza vaccination received less than one year after rituximab
           and greater than one year after rituximab.
    

Intervention name(s): Inactivated Trivalent Influenza vaccine
Intervention type(s): Biological
Intervention model: Single Group Assignment
Masking: None (Open Label)
Keywords: ITP; Rituximab; Vaccine; Immune Reconstitution