Low-dose immune tolerance induction alone or with immunosuppressants according to prognostic risk factors in Chinese children with hemophilia A inhibitors

Low-dose immune tolerance induction for severe hemophilia A inhibitor patients: Immunosuppressants are generally not necessary for inhibitor-titer below 200 BU/mL

Importance

It remained unclear that the efficacy comparison between low-dose immune tolerance induction (LD-ITI) incorporating immunosuppressants (IS) when severe hemophilia A (SHA) patients had inhibitor-titer ≥200 Bethesda Units (BU)/mL (LD-ITI-IS200 regimen) and LD-ITI combining with IS when SHA patients had inhibitor-titer ≥40 BU/mL (LD-ITI-IS40 regimen).

Objective

To compare the efficacy of the LD-ITI-IS200 regimen with that of the LD-ITI-IS40 regimen for SHA patients with high-titer inhibitors.

Methods

A prospective cohort study on patients receiving LD-ITI-IS200 compared to those receiving LD-ITI-IS40 from January 2021 to December 2023. Both received LD-ITI [FVIII 50 IU/kg every other day]. IS (rituximab + prednisone) was added when peak inhibitor tier ≥200 BU/mL in the LD-ITI-IS200 regimen and ≥40 BU/mL in the LD-ITI-IS40 regimen. Success is defined as a negative inhibitor plus FVIII recovery ≥66% of the expected.

Results

We enrolled 30 patients on LD-ITI-IS200 and 64 patients on LD-ITI-IS40, with similar baseline clinical characteristics. A lower IS-use rate was discovered in the LD-ITI-IS200 regimen compared to the LD-ITI-IS40 regimen (30.0% vs. 62.5%). The two regimens (LD-ITI-IS200 vs. LD-ITI-IS40) had similar success rate (70.0% vs. 79.7%), median time to success (9.4 vs. 10.6 months), and annualized bleeding rate during ITI (3.7 vs. 2.8). The cost to success was lower for LD-ITI-IS200 than for LD-ITI-IS40 (2107 vs. 3256 US Dollar/kg). Among patients with peak inhibitor-titer 40-199 BU/mL, 10 non-IS-using (on LD-ITI-IS200 regimen) and 28 IS-using (on LD-ITI-IS40 regimen) had similar success rates (70.0% vs. 78.6%) and time to success (9.0 vs. 8.8 months).

Interpretation

In LD-ITI, IS are not necessary for inhibitor titer <200 BU/mL.

National strategic advocacy to manage patients with inherited bleeding disorders in low and lower-middle income countries

INTRODUCTION

Inherited bleeding disorders (IBDs) including hemophilia, von Willebrand disease, platelet disorders, mucocutaneous bleeding disorders and coagulation factor deficiencies are rarely found and under-recognized in low and lower-middle-income countries. Some patients succumbed to serious bleeding without diagnosis and treatment during childhood.

AREA COVERED

Diagnosis, management, and prevention should be integrated into the existing health care system. Although some countries have not implemented appropriate health care infrastructure, an initiative plan should be set up by cooperation of experienced experts and health care providers. Identification of patients with IBDs should be started in the antenatal setting to search for females at risk of carrier state. The investigations include bleeding assessment, mixing venous clotting time, coagulogram, coagulation factor assay and mutation detection. Genotypic analysis is helpful for confirming the definite diagnosis, carrier detection as well as prenatal diagnosis for females at risk of bearing an offspring with severe bleeding manifestations. Management involves replacement therapy ranging from blood component to virus-inactivated factor concentrate. Appropriate research is an essential backbone for improving patients' care.

EXPERT OPINION

Effective national strategic advocacy to manage patients with IBDs requires intensive collaboration among policy makers, health care providers, patients, and family members.

Low-dose immune tolerance induction therapy in severe hemophilia a children in China: Starting earlier resulted in better inhibitor eradication outcomes

BACKGROUND

Shorter interval-time from inhibitor detection to starting immune tolerance induction (ITI) might predict better ITI outcomes for severe Hemophilia A (SHA) patients with high-risk-inhibitors. However, the prediction-impact of interval-time for these patients on low-dose ITI strategy remained unclear.

OBJECTIVES

To explore the relationship between interval-time and low-dose ITI outcomes in Chinese SHA children with high-risk-inhibitors.

METHODS

This was a single-center, retrospective study on SHA children with high-risk-inhibitors (each with immediate pre-ITI inhibitor titer>10 Bethesda Units/mL) undergoing low-dose ITI strategy for ≥24 months. ITI outcomes and their predictive factors were evaluated at the 24th month treatment for each patient. The predictive ability of interval-time on ITI success was determined using receiver operating characteristic (ROC) curve.

RESULTS

Among 47 patients investigated, 34 (72.3 %) achieved success. Independent predictor for ITI-outcome on multivariate analysis included the interval-time (p = 0.007) and peak inhibitor-titer (p = 0.011). Shorter interval-time predicted ITI success [cut-off value = 22.3 months, area under ROC-curve (AUC) = 0.701] and early-ITI success within 12 month (cut-off value = 9.4 months AUC = 0.704). Linear regression analysis suggested each month interval-time delay delayed success by 0.1552 month. Unlike the interval-time, peak inhibitor-titer had no success-predictive value in high-peak inhibitor-titer patients on ITI with immunosuppressants.

CONCLUSIONS

Interval-time represented a strong predictive value for outcomes in our low-dose ITI strategy for SHA patients with high-risk-inhibitors. Shorter interval-time was associated with higher success rate and earlier success achievement. The respective interval-time cut-off values were 22.3 months for ITI success and 9.4 months for early-success.

Eradication of FIX inhibitor in haemophilia B children using low-dose immune tolerance induction with rituximab-based immunosuppressive agent(s) in China

INTRODUCTION

Development of haemophilia B inhibitors (HBI) results in the ineffectiveness of FIX replacement therapy. Inhibitor eradication by immune tolerance induction (ITI) is therefore necessary. In HBI, ITI even at high FIX dose is less effective and has a higher risk of severe complications.

AIM

To characterize clinical features and outcome of ITI on HBI.

METHODS

This retrospective study was conducted in Haemophilia Paediatric Comprehensive Care Centre of China. We used low-dose ITI (25-50 FIX IU/kg/three-times-weekly to every-other-day) with domestic prothrombin complex concentrate (PCC), combined with two successive immunosuppressive (IS) regimens.

RESULTS

Sixteen HBI children, representing 5.7% of all and 14.4% of our severe registered HB patients, were enroled. Seven cases reported allergic reactions (ARs) proximal to inhibitor development. The historic peak inhibitor titre was median 54.2 (range 4.7-512) BU, and 15 (93.8%) had high-titre inhibitors. Twelve patients adherent to ITI were analysable. Of the nine ITI patients who received rituximab/prednisone (IS Regimen-1), four achieved tolerization in 1.4-43.3 months. Two subsequently relapsed but re-tolerized after a second course of IS Regimen-1. During ITI, the median treated bleed was .39/month (82.7% reduction from before ITI), and the incidence of AR and nephrotic syndrome (NS) complications was each at 22% (2/9). Three ITI patients received modified 'Beutel' protocol (IS Regimen-2) using multiple-IS-drugs, and two had rapid tolerization (.8 and 1.8 months).

CONCLUSIONS

Inhibitor eradication could be achieved by low-dose ITI protocol using PCC combined with IS. Larger studies are needed to confirm if ITI with IS Regimen-2 is more effective with less complications.