Chimeric Anti CD-20 Monoclonal Antibody-Rituximab in Refractory Childhood Idiopathic Thrombocytopenic Purpura: An Indian Experience.

The treatment of chronic idiopathic thrombocytopenic purpura (ITP) continues to be a challange. A significant proportion of patients continue to be symptomatic despite all available means of therapy. Recently Rituximab, a chimeric anti CD-20 monoclonal antibody has been shown to be an effective mode of therapy in such patients with an overall response rate of appx 50 %.

We studied the efficacy and side effects of this therapeutic modality in 10 children (6 girls) with chronic ITP. The patients belonged to pediatric age group (median age: 9 years, range 4–18 years) with 4 children less than 10 years of age. All the patients were screened for systemic illnesses and different secondary causes leading to thrombocytopenia. They all had been treated with standard therapies using conventional and high dose steroids, ciclosporin cyclophosphamide, vincristine, periodic use of high dose IVIG and splenectomy in 6 patients, but had continued to be symptomatic with recurrent mucocutaneous bleeds and markedly low platelet counts (< 20x 10⁹/L). All patients received intravenous Rituximab at a dose of 375 mg/M² as weekly dose for 4 consecutive weeks. The infusion related side effects were a few (n= 3) and minor. They included urticarial rash (1) and fever(2) that responded to antipyretics. None of these were severe enough to interrupt the treatment. A complete response was defined as a platelet count > 100 x 10⁹/L, partial response (PR) as count > 50x10⁹/L and a minor response as a count < 50x10⁹/L but without the need of continued treatment. Patients showing no significant rise in platelet count were marked as showing no response. Of the 10 evaluable children, 9 (90%) showed overall response; 4 (40%) showed complete response and 4 (40 %) showed partial response. Two (20%) patients showed minor responses. Patients have been under follow up for last 3 years. The patients with CR and PR have been in remission for longer periods (as much as 150 weeks ).The side effects due to the therapy have been few and very mild. Besides infusional reactions in 3 patients (Transient fever in 2 and mild rash in 1) there were no significant toxicities. No correlation could be found between clinical/laboratory parameters with the responsiveness or the duration of response except that patients showing a higher degree of response continued to be in remission for a longer period as compared to the ones with lesser degree of response. The high percentage of response in our patients as compared to the ones in other studies could be due to the fact that our patients belonged to a younger age group. Probably children show a better response.

In conclusion, Rituximab offers a safe and convenient modality of treatment in symptomatic children with refractory ITP. Its use is certainly cost effective even in a developing country in view of the good degree of a sustained response in these refractory patients wherein all modalities of treatment have failed.