Treatment of chronic immune thrombocytopenic purpura with rituximab in children

Thrombopoietin receptor agonists and rituximab for treatment of pediatric immune thrombocytopenia: A systematic review and meta-analysis of prospective clinical trials

BACKGROUND

Children with immune thrombocytopenia (ITP) may require second-line ITP therapies. The high remission rate in pediatric patients, need for extended-duration use of thrombopoietin receptor agonists (TPO-RAs), drug adherence, potential side effects, monitoring, and cost effectiveness are factors that should be considered in decision-making about second-line therapies. Rituximab (RTX) has been used off-label for years to treat ITP but there are limited studies about its efficacy and safety in children. To date, no studies have directly compared TPO-RAs with RTX for the treatment of childhood ITP.

METHODS

This systematic review analyzed the overall platelet response, durability of treatment effect, and safety for RTX use in comparison to TPO-RAs in pediatric ITP. MEDLINE/PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched through December 2020 and meta-analysis was conducted using proportions of success/failure for each intervention in the selected studies.

RESULTS

The proportion of participants achieving the primary endpoint of a platelet response above 50,000 was similar for TPO-RAs (proportion = 0.71, 95% CI: 0.63-0.78) and RTX (proportion = 0.68, 95% CI: 0.53-0.82). However, considerable variation was found between the two groups with regards to the sustainability of the response and other secondary outcomes such as need for rescue and adverse events. RTX was associated with higher rates of rescue therapy.

CONCLUSIONS

In this analysis of prospective pediatric ITP studies, RTX and TPO-RAs had similar rates of overall platelet response but differed in other important measures. Prospective comparative studies are needed to better characterize second-line treatments for pediatric ITP.

Efficacy and safety of rituximab for minors with immune thrombocytopenia: a systematic review and meta-analysis

Objective

We reviewed relevant research on rituximab (RTX) treatment for pediatric immune thrombocytopenia (ITP) to elucidate the efficacy and safety of RTX.

Methods

Prospective clinical trials of RTX for the treatment of pediatric ITP were collected by searching the PubMed, Cochrane Library, Web of Science, and OVID: EMBASE databases and ClinicalTrials.gov. We examined rates of overall response (OR), complete response (CR), partial response (PR), sustained response (SR), relapse (R), and adverse drug reaction (ADR). The Methodological Index for Nonrandomized Studies scale was used, and sensitivity analyses were performed.

Results

For five studies, including 100 patients, the pooled OR, CR, PR, SR, R, and ADR rates were 52% (95% CI: 0.36–0.77, I² = 78%), 52% (95% CI: 0.41–0.67, I² = 45%), 18% (95% CI: 0.10–0.33, I² = 33%), 43% (95% CI: 0.29–0.63, I² = 0%), 25% (95% CI: 0.06–0.96, I² = 52%), and 30% (95% CI: 0.15–0.58, I² = 64%), respectively.

Conclusion

There is evidence, albeit low quality, that RTX may be a better second-line therapy than splenectomy for children with ITP; however, its efficacy and safety need to be validated by further high-quality clinical trials, such as randomized controlled trials.

Long-term follow-up of children with refractory immune thrombocytopenia treated with rituximab

Data on long-term outcomes of children with refractory immune thrombocytopenia (ITP) treated with rituximab are limited. We retrospectively analyzed the long-term effect of rituximab on 22 pediatric ITP patients (11 boys and 11 girls). Compete response (CR) (platelet count ≥100 × 10(9)/L) and partial response (PR) (platelet count 30-99 × 10(9)/L) were achieved in nine (41 %) and two (9 %) patients, respectively. Of the 11 responders, eight subsequently relapsed 2-26 months after initial rituximab treatment. The 5-year relapse-free rate was 14 % (3/22, 95 % confidence interval: 0-27 %) with a median follow-up period of 6.4 years. Five initial responders with subsequent relapse and one non-responder received multiple rituximab treatments of nine courses; all patients responded to the second rituximab therapy without any significant toxicity. All eight patients who relapsed after an initial response and six of 11 non-responders achieved CR or PR with subsequent treatment, including repeated courses of rituximab, splenectomy, steroids, and other immunomodulating agents. Our findings indicated that the sustained effect of rituximab on children with refractory ITP is low, but that the long-term outcome of ITP itself is not poor. Furthermore, repeated rituximab administration may be a promising therapy for those who relapse after an initial response.

Evaluation of children with chronic immune thrombocytopenic purpura and Evans syndrome treated with rituximab

The primary objective was to evaluate the response rate of rituximab therapy for children with chronic immune thrombocytopenic purpura (ITP) and Evans syndrome (ES) and immune reconstitution of these children after rituximab therapy. Eleven patients with chronic ITP and 2 with ES between 6 and 18 years of age and platelet count less than 20 × 10(9)/L received rituximab. Overall response (OR) was defined as an increase in platelet count above 50 × 10(9)/L. The mean age of 13 children (9 girls, 4 boys) was 11.2 ± 3.8 years (6-18). One of the patients with ES had been splenectomized; others were not. The patients mean follow-up time was 10.3 ± 9.3 months after rituximab therapy. Two patients achieved complete response, 4 patients achieved partial response, and OR rate was 46% (6 of 13) after therapy. Seven patients have no response. In conclusion, rituximab may be considered prior to splenectomy in children with chronic ITP and ES with an acceptable toxicity profile.

Rituximab for children with immune thrombocytopenia: a systematic review

Background

Rituximab has been widely used off-label as a second line treatment for children with immune thrombocytopenia (ITP). However, its role in the management of pediatric ITP requires clarification. To understand and interpret the available evidence, we conducted a systematic review to assess the efficacy and safety of rituximab for children with ITP.

Methodology/Principal Findings

We searched MEDLINE, EMBASE, Cochrane Library, CBM, CNKI, abstract databases of American Society of Hematology, American Society of Clinical Oncology and Pediatric Academic Society. Clinical studies published in full text or abstract only in any language that met predefined inclusion criteria were eligible. Efficacy analysis was restricted to studies enrolling 5 or more patients. Safety was evaluated from all studies that reported data of toxicity. 14 studies (323 patients) were included for efficacy assessment in children with primary ITP. The pooled complete response (platelet count ≥100×10⁹/L) and response (platelet count ≥30×10⁹/L) rate after rituximab treatment were 39% (95% CI, 30% to 49%) and 68% (95%CI, 58% to 77%), respectively, with median response duration of 12.8 month. 4 studies (29 patients) were included for efficacy assessment in children with secondary ITP. 11 (64.7%) of 17 patients associated with Evans syndrome achieved response. All 6 patients with systemic lupus erythematosus associated ITP and all 6 patients with autoimmune lymphoproliferative syndrome associated ITP achieved response. 91 patients experienced 108 adverse events associated with rituximab, among that, 91 (84.3%) were mild to moderate, and no death was reported.

Conclusions/Significance

Randomized controlled studies on effect of rituximab for children with ITP are urgently needed, although a series of uncontrolled studies found that rituximab resulted in a good platelet count response both in children with primary and children secondary ITP. Most adverse events associated with rituximab were mild to moderate, and no death was reported.

Response to steroids predicts response to rituximab in pediatric chronic immune thrombocytopenia

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.

CONCLUSION

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.

The clinical outcome of 260 pediatric ITP patients in one center

In the current study, clinical and laboratory findings and treatment modalities of children with acute and chronic immune thrombocytopenic purpura (ITP) were evaluated retrospectively. Our purpose was to determine clinical outcome of children with ITP and their responses to different treatment regimes. Total of 260 children with ITP were enrolled in the study. The mean age of patients was 76.8 ± 48.1 months. The therapy responses of high-dose methylprednisolone (HDMP; n = 134), standard dose methylprednisolone (n = 32), and intravenous immunoglobulin (IVIG; n = 15) treatments were similar. Two (0.8%) of the 260 ITP patients had intracranial bleeding. None of the patients died due to hemorrhage. Of all the patients with ITP, 191 (73.5%) completely resolved within 6 months after initiation of the disease and therefore they were diagnosed as acute ITP; 69 patients (26.5%) had progressed into chronic ITP. The therapy responses of HDMP, standard dose methylprednisolone, and IVIG treatments are similar.