Platelet count recovery after intravenous immunoglobulin predicts a favorable outcome in children with immune thrombocytopenia

Retrospective evaluation of the short-term response of human intravenous immunoglobulin therapy in the management of canine immune-mediated thrombocytopenia (2010-2015): 27 cases

OBJECTIVE

To describe the short-term response, early prognostic markers, and survival after treatment of canine immune-mediated thrombocytopenia (ITP) with human intravenous immunoglobulin (hIVIG) and methylprednisolone.

DESIGN

Retrospective cohort study.

SETTINGS

Private referral veterinary medical center.

ANIMALS

Twenty-seven client-owned dogs with primary or secondary ITP.

INTERVENTIONS

All dogs received 2 mg/kg IV methylprednisolone once daily and a single infusion of 5% hIVIG administered over 6-12 hours.

MEASUREMENTS AND MAIN RESULTS

A substantial increase in platelet count within 60 ± 12 hours post-hIVIG infusion (T60) was observed in 19 of the 27 (70%) dogs with ITP (responders). Thirty-four variables, including serum immunoglobulin (Ig) G concentration 24 ± 12 hours post-hIVIG infusion (T24IgG) and increase in serum IgG concentration 24 ± 12 hours post-hIVIG infusion (T24ΔIgG), were compared between responders and nonresponders at 5 different time points. Mortality rates of responders and nonresponders were evaluated 14 days post-hIVIG infusion. Serum T24IgG and serum T24ΔIgG were both significantly higher at T60 in responders. All responders were alive 14 days post-hIVIG infusion, and their mortality rate was significantly lower compared with nonresponders.

CONCLUSIONS

Responder dogs had an excellent 14-day survival rate. Serum T24IgG and serum T24ΔIgG concentrations accurately predicted response status at 60 hours post-hIVIG infusion.

Prediction of the Clinical Course of Immune Thrombocytopenia in Children by Platelet Kinetics

Childhood immune thrombocytopenia (ITP) is a rare autoimmune disorder characterized by isolated thrombocytopenia. Prolonged ITP (persistent and chronic) leads to a reduced quality of life for children in many domains. To provide optimal support for children, with ITP, it is important to be able to predict those who will develop prolonged ITP. This study aimed to develop a mathematical model based on platelet recovery that allows the early prediction of prolonged ITP. In this retrospective study, we used platelet counts from the 6 months following the diagnosis of ITP to model the kinetics of change in platelet count using a pharmacokinetic-pharmacodynamic model. In a learning set (n = 103), platelet counts were satisfactorily described by our kinetic model. The Kheal parameter, which describes spontaneous platelet recovery, allowed a distinction between acute and prolonged ITP with an area under the curve (AUC) of 0.74. In a validation set (n = 58), spontaneous platelet recovery was robustly predicted using platelet counts from 15 (AUC = 0.76) or 30 (AUC = 0.82) days after ITP diagnosis. In our model, platelet recovery quantified using the kheal parameter allowed prediction of the clinical course of ITP. Future prospective studies are needed to improve the predictivity of this model, in particular, by combining it with the predictive scores previously reported in the literature.

Severe immune thrombocytopenic purpura after SARS-CoV-2 vaccine

Immune thrombocytopenic purpura (ITP) is a rare hematologic condition through to affect 3.3 in 100,000 adults per year in the United States. Many cases of immune thrombocytopenia are diagnosed incidentally with laboratory tests that reveal low platelet count, without a clear cause. However, when platelet counts are very low, patients may show signs of bleeding. Here we present the case of a 24-year-old female with mucocutaneous bleeding ten days after receiving her first dose of SARS-CoV-2 vaccine, who was subsequently found to have severe thrombocytopenia. Extensive work up for new thrombocytopenia was unremarkable suggesting a diagnosis of ITP, potentially secondary to vaccination. Empiric treatment with glucocorticoids was initiated without response prompting the use of intravenous immunoglobulin G. The patient was discharged on hospital day five with a platelet count over 20,000 platelets per microliter. In summary, ITP is a potential sequela of the SARS-CoV-2 vaccine, and otherwise healthy young individuals may be at risk for hematologic side effects.

Biological stratification of clinical disease courses in childhood immune thrombocytopenia

BACKGROUND

In childhood immune thrombocytopenia (ITP), an autoimmune bleeding disorder, there is a need for better prediction of individual disease courses and treatment outcomes.

OBJECTIVE

To predict the response to intravenous immunoglobulins (IVIg) and ITP disease course using genetic and immune markers.

METHODS

Children aged younger than 7 years with newly diagnosed ITP (N = 147) from the Treatment With or Without IVIG for Kids with ITP study were included, which randomized children to an IVIg or observation group. A total of 46 variables were available: clinical characteristics, targeted genotyping, lymphocyte immune phenotyping, and platelet autoantibodies.

RESULTS

In the treatment arm, 48/80 children (60%) showed a complete response (platelets ≥100 × 109 /L) that lasted for at least 1 month (complete sustained response [CSR]) and 32 exhibited no or a temporary response (absence of a sustained response [ASR]). For a biological risk score, five variables were selected by regularized logistic regression that predicted ASR vs CSR: (1) hemoglobin; (2) platelet count; (3) genetic polymorphisms of Fc-receptor (FcγR) IIc; (4) the presence of immunoglobulin G (IgG) anti-platelet antibodies; and (5) preceding vaccination. The ASR sensitivity was 0.91 (95% confidence interval, 0.80-1.00) and specificity was 0.67 (95% confidence interval, 0.53-0.80). In the 67 patients of the observation arm, this biological score was also associated with recovery during 1 year of follow-up. The addition of the biological score to a predefined clinical score further improved the discrimination of favorable ITP disease courses.

CONCLUSIONS

The prediction of disease courses and IVIg treatment responses in ITP is improved by using both clinical and biological stratification.

Transient and chronic childhood immune thrombocytopenia are distinctly affected by Fc-γ receptor polymorphisms

In childhood immune thrombocytopenia (ITP), anti-platelet autoantibodies mediate platelet clearance through Fc-γ receptor (FcγR)-bearing phagocytes. In 75% to 90% of patients, the disease has a transient, self-limiting character. Here we characterized how polymorphisms of FcγR genes affect disease susceptibility, response to intravenous immunoglobulin (IVIg) treatment, and long-term recovery from childhood ITP. Genotyping of the FCGR2/3 locus was performed in 180 children with newly diagnosed ITP, 22 children with chronic ITP, and 180 healthy control children by multiplex ligation-dependent probe amplification. Children with newly diagnosed ITP were randomly assigned to a single administration of IVIg or observation, and followed for 1 year (Treatment With or Without IVIg for Kids With ITP [TIKI] trial). We defined transient ITP as a complete recovery (≥100 × 10⁹/L) 3 months after diagnosis, including both self-limiting disease/IVIg responders and chronic ITP as absence of a complete recovery at 12 months. ITP susceptibility, as well as spontaneous recovery and response to IVIg, was associated with the genetic variants FCGR2C*ORF and FCGR2A*27W and the FCGR2B promoter variant 2B.4. These variants were overrepresented in patients with transient (N = 131), but not chronic (N = 43), disease. The presence of FCGR2C*ORF predisposed to transient ITP with an odds ratio of 4.7 (95% confidence interval, 1.9-14.3). Chronic ITP was associated with a deletion of FCGR2C/FCGR3B (copy number region 1) with an odds ratio of 6.2 (95% confidence interval, 1.8-24.7). Taken together, susceptibility to transient and chronic ITP is distinctly affected by polymorphic variants of FCGR2/3 genes. Our data suggest that genotyping of the FCGR2/3 locus may be useful for prognosis and guidance of treatment decisions in newly diagnosed childhood ITP.

Platelet-specific antibodies and differences in their expression in childhood immune thrombocytopenic purpura predicts clinical progression

IMPORTANCE

Immune thrombocytopenic purpura (ITP) is the most common bleeding disorder in children. Despite the highly spontaneously remission, still almost 20% of cases progress into chronic or refractory ITP, which seriously affects children's quality of life. Currently there is no method to predict the initial stage of childhood ITP.

OBJECTIVES

To evaluate platelet-specific antibodies and compare differences in their expression in childhood ITP to predict clinical progression.

METHODS

This is a single-center prospective cohort study from April 2014 to October 2015. We enrolled children initially diagnosed as ITP. Anti-GPIIb/IIIa and GPIb/IX antibodies were assayed by enzyme-linked immunoadsorbent assay (ELISA) and patients were followed up for 1 year. We also analyzed the relationship between the expression of the platelet-specific antibodies GPIIb/IIIa and GPIb/IX and their respective clinical prognoses.

RESULTS

Overall, 134 cases were enrolled including 77 boys and 57 girls with a median age of 19 months (range: 1 to 159). Positive rates of anti-platelet antibodies were 79.8%. After a 1-year observation period, 84.3% were diagnosed as newly diagnosed ITP and 13.4% were diagnosed as chronic ITP. Patients with anti-GPIIb/IIIa antibody had a higher risk for newly diagnosed ITP compared with patients who were anti-GPIb/IX antibody positive only (93% vs 25%, P = 0.005; 87% vs 25%, P = 0.014, respectively). There were more anti-GPIb/IX antibody positive only cases, diagnosed as chronic ITP, compared with anti-GPIIb/IIIa antibody positive only cases and double GPIIb/IIIa and GPIb/IX antibody positive cases (75% vs 7%, P = 0.005; 75% vs 13%, P = 0.014, respectively). Interpretation.

INTERPRETATION

Patients with anti-GPIIb/IIIa antibody (either single or double) were predicted to have a good prognosis, whereas anti-GPIb/ IX antibody only predicted a poor prognosis. These results should be confirmed via a larger cohort multicenter study.

Management of immune thrombocytopenia: Korean experts recommendation in 2017

Management options for patients with immune thrombocytopenia (ITP) have evolved substantially over the past decades. The American Society of Hematology published a treatment guideline for clinicians referring to the management of ITP in 2011. This evidence-based practice guideline for ITP enables the appropriate treatment of a larger proportion of patients and the maintenance of normal platelet counts. Korean authority operates a unified mandatory national health insurance system. Even though we have a uniform standard guideline enforced by insurance reimbursement, there are several unsolved issues in real practice in ITP treatment. To optimize the management of Korean ITP patients, the Korean Society of Hematology Aplastic Anemia Working Party (KSHAAWP) reviewed the consensus and the Korean data on the clinical practices of ITP therapy. Here, we report a Korean expert recommendation guide for the management of ITP.