Low-dose immune tolerance induction for children with hemophilia A with poor-risk high-titer inhibitors: A pilot study in China

Intermediate-dose immune tolerance induction outperforms with faster success, less bleeding, and no added cost in comparison with low dose: a multicenter randomized clinical trial

Background

Low-dose (LD) or intermediate-dose (MD) immune tolerance induction (ITI) is effective in children with severe hemophilia A (SHA) with high-titer inhibitors (HTIs) and is attractive in countries with economic constraints. However, high-quality evidence of their use is lacking.

Objectives

This was a multicenter randomized clinical trial comparing the efficacy, safety, and medication cost between LD-ITI and MD-ITI for SHA-HTI children.

Methods

Children with SHA aged <8 years with historical/pre-ITI inhibitor titer 5 to 200 Bethesda Units/mL in 3 centers were randomized 1:1 to receive LD-ITI (recombinant factor VIII [rFVIII] 50 IU/kg every other day) or MD-ITI (rFVIII 100 IU/kg/d) from January 2022 to June 2024 (ChiCTR2200056603, https://www.chictr.org.cn).

Results

Thirty-one patients (16 in MD-ITI and 15 in LD-ITI) were enrolled and followed for >24 months (median, 26.9; range, 24.0-29.5 months). The 2 groups had similar baseline clinical characteristics and similar success rates (93.8% [MD-ITI] vs 86.7% [LD-ITI]). Compared with LD-ITI, MD-ITI patients took a shorter median time to success (4.2 months vs 10.1 months) and partial success (2.7 months vs 6.6 months) and had lower mean rates for all bleeding (0.38/mo vs 1.40/mo) and joint bleeding (0.11/mo vs 0.83/mo). Between the 2 groups, although the MD-ITI group had higher rFVIII consumption (12,775 vs 7680 IU/kg), their total medication costs to success were similar (3626.49 vs 3240.38 US$/kg).

Conclusion

For SHA-HTI children, the success rate and cost for MD-ITI and LD-ITI regimens were similar. MD-ITI regimen would be a priority for regions with economic constraints, considering the shorter time to success, better bleeding control, and no increase in medication cost.

Treatment-related outcome from patient report outcome (PRO) of children with severe and moderate hemophilia A in China: An analysis report of registration data from patient organization "hemophilia home care center"

OBJECTIVES

To assess current treatment-related outcomes for children with severe and moderate haemophilia A (cHA) in China.

METHODS

This cross-section Patient Report Outcome (PRO) report collected PRO data of severe and moderate cHAs registered in the 'Hemophilia Home Care Center' database (http://web.bjxueyou.cn) between January 2021 and November 2022. Data included records of bleeding, activities, and concentrates consumption. All patients had a confirmed diagnosis of moderate or severe haemophilia A (FVIII: C ≤ 5%) and were < 18 years old.

RESULTS

Among 1038 analysable cases, 9.6% of children with inhibitors had a higher rate of intracranial haemorrhage, dropout school rate, and higher FVIII consumption than children without inhibitors. Among 100 children with inhibitors, 36 patients were treated without immune tolerance induction (ITI), 14 patients with irregular treatment and 50 patients received ITI. Children with ITI had a lower ABR (2.4 (0,6.6) vs. 13.4 (9.5, 26.6), p<.001) and AJBR (0 (0, 3.1) vs. 8.9 (1.6, 19.3), p < .001) compared to those without ITI. Among 938 children without inhibitors, 28.5% received on-demand treatment and 71.5% received prophylaxis. Of 528 children with 1343.8 (1050.4, 2922.9)IU/kg/year median FVIII consumption, 43.0% received low-dose, 43.2% received intermediate-dose, and 13.8% received high-dose regimen; these children with prophylaxis had a lower ABR (3.1 (0, 10.7) vs. 12.8 (2.4, 45.5), p < .001), AJBR (0.5 (0, 3.9) vs. 3.0 (0, 12.0), p < .001) and disability rate (9.0% vs.18.5%, p = .032) compared to children who received on-demand treatment.

CONCLUSION

The high rate of drop-out of school and disability still present a huge gap to meet the needs in China. It is necessary to improve the level of medical accessibility and medicine affordability and strengthen the patient/parent's education in China.

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.

Central venous access devices implantation in children with severe hemophilia a: data from the children comprehensive care center of China

Objectives

To report the perioperative management experience of central venous access devices (CVAD) in Chinese children with severe hemophilia A (SHA) in China.

Methods

This retrospective study included SHA children who underwent Port-A-Cath or peripherally inserted central catheter (PICC) implantation between 2020/01 and 2021/07. Collected data included baseline characteristics, factor replacement regimen and CVAD-related complications.

Results

Nine patients had nine ports placed, and eight patients underwent 10 PICCs placement. Patients without or with low-titer inhibitor (<5 BU) received a port. The median preoperative and postoperative plasma-derived factor VIII (pd-FVIII) doses were 53.0 (44.4-61.1) and 315.9 (88.2-577.8) IU/kg. The median port duration was 189 (15-512) days, with infection incidence of 0.06 per 1000 CVAD days. Patients with high-titer inhibitors (>10 BU) received PICC. The median recombinant factor VIIa (rFVIIa) dose was 87.47 μg/kg before and for 5-7 doses after implantation over 2-3 days. The median PICC duration was 226.5 days, with infection incidence of 0.12 per 1000 catheter-days.

Conclusions

CVADs can be safely implanted in China. PICC implantation is a practical and safe option for SHA children with high-titer inhibitors.

Inhibitors: Diagnostic challenges, unknowns of inhibitor development, treatment of bleeding and surgery, and insights into diagnosis and treatment in China

Factor (F) VIII inhibitors develop in around 30% of previously untreated patients (PUPs) with severe haemophilia, to a lesser extend in moderate and mild haemophilia A and in up to 10% in severe haemophilia B. Diagnostic challenges and questions remain including access to high quality testing, the role for functional inhibitor testing and binding antibody testing, and the adaptations needed in the presence of non-factor replacement therapy. Despite significant gains in knowledge there are still many unanswered questions underlying the immunologic mechanisms of inhibitor development and tolerance. Therapeutic options include eradication of inhibitors using immune tolerance induction therapy (ITI), prophylaxis with bypassing agents (i.e., recombinant activated factor VII /rFVIIa or activated prothrombin complex concentrate/aPCC) or non-factor replacement therapies (e.g., emicizumab) and treatment of bleeds or coverage of surgeries/invasive procedure. Recently a haemophilia centre capacity building program was launched in China to further develop the infrastructure and support needed to improve the diagnosis of haemophilia, detection of inhibitors, and continue to improve the care of patients with haemophilia and inhibitors.

Low-dose immune tolerance induction therapy in children of Arab descent with severe haemophilia A, high inhibitor titres and poor prognostic factors for immune tolerance induction treatment success

INTRODUCTION

Immune Tolerance Induction (ITI) is the first-choice therapy to eradicate Factor VIII (FVIII) neutralizing antibodies in patients with haemophilia A (HA). There is limited published data on ITI from East Mediterranean countries.

AIM

To assess the effectiveness of a low-dose ITI regimen to eradicate FVIII neutralizing antibodies in children with severe HA and high-titre inhibitors.

METHODS

A prospective, single-arm study was conducted in children with HA (FVIII < 1 IU/dl), high-titre inhibitors and poor prognostic factors for successful ITI. Patients were treated with ∼50 IU/kg plasma-derived FVIII containing von Willebrand factor (pdFVIII/VWF) concentrate (Koate-DVI, Grifols) three times a week. Time to achieve tolerance, total and partial success were analysed after ITI. Annual bleeding rate (ABR), number of target joints, FVIII recovery and school absence were compared before and after ITI.

RESULTS

Twenty patients with median (range) age of 6.2 (3-12) years and pre-ITI inhibitor titre of 36.5 (12-169) BU were enrolled. ITI lasted ≤12 months (early tolerization) in 45% of patients. Median follow-up was 12 months (3-22) and total response rate was 80% (60% total success; 20% partial success). Patients with two and three poor prognosis factors achieved overall success rate of 60% and 50%, respectively. ABR, target joints and school absence were reduced after ITI by 60%, 50% and 44.1%, respectively. In successful ITI tolerized patients, FVIII recovery was 90 (60-100)%.

CONCLUSION

A low-dose ITI therapy using a pdFVIII/VWF concentrate achieved at least partial tolerance in 80% of patients, and reduced annual bleeds in children with high inhibitor titres and at least one poor prognosis factor for ITI treatment success.

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

BACKGROUND

In developing countries, children with hemophilia A (HA) with high-titer inhibitor and poor immune tolerance induction (ITI) prognostic risk(s) cannot afford the recommended high- or intermediate-dose ITI.

OBJECTIVES

To determine the efficacy of low-dose ITI (plasma-derived factor VIII [FVIII]/von Willebrand factor at 50 FVIII IU/kg every other day) by itself (ITI-alone) or combined with immunosuppressants rituximab and prednisone (ITI-IS) in children with HA with high-titer inhibitor.

METHODS

All enrolled patients had pre-ITI inhibitor ≥10 BU. We used ITI-alone if inhibitor titer was <40 BU pre-ITI and during ITI, and ITI-IS if titer was ≥100 BU (historic) or ≥40 BU (pre- or during ITI) or if the patient was nonresponsive on ITI-alone.

RESULTS

Fifty-six children were analyzable, with median historic peak inhibitor titer 48.0 BU and followed for median 31.4 months. Overall, 35 (62.5%) achieved phase 2 success with negative inhibitor and normal FVIII recovery. The phase 2 success rate was 95% for the 20 patients receiving ITI-alone. For the 36 patients receiving ITI-IS, the phase 2 success rate was 44.4%, but would increase to 63.6% if the 14 patients with historic peak inhibitor titer ≥100 BU (and having phase 2 success rate of only 14.3%) were excluded. One patient developed repeated infection after IS treatment. Relapse occurred in 11.4% (4/35) patients with phase 2 success associated with rapid ITI dose reduction or irregular post-ITI FVIII prophylaxis. Our strategy reduced the cost from high-dose ITI by 74% to 90%.

CONCLUSION

The use of low-dose ITI with or without immunosuppressants according to ITI prognostic risk(s) is a clinically and economically feasible strategy for eradicating inhibitors in children with HA, particularly for those with historic peak inhibitor titer <100 BU.

Patients with haemophilia A with inhibitors in China: a national real-world analysis and follow-up

The development of alloantibodies (inhibitors) against coagulation factor VIII (FVIII) is the most serious complication of FVIII replacement therapy in patients with haemophilia A (HA). We carried out a nationwide study focussing on patients with HA with inhibitors in China to evaluate the condition and management of this population. The study retrospectively analysed patient characteristics, clinical history, manifestation, treatment strategy as well as individual haemophilia care of 493 patients with inhibitors (466 with severe HA and 27 with non-severe HA) registered all over China. The median (interquartile range) age at diagnosis of FVIII inhibitors was 13 (5-28) years in patients with severe HA and 24 (10·5-39·5) years in patients with non-severe HA. Most patients (85%) had high-titre inhibitors. Prothrombin complex concentrate and recombinant activated coagulation factor VII were used respectively in 76·2% and 29·2% of patients for acute bleeding. Only 22·3% of patients underwent immune tolerance induction (ITI) treatment, of whom 64·9% achieved negative inhibitor titre. In patients who did not undergo ITI, the inhibitors turned negative in 17·7%, and patients with low peak inhibitor titre were more likely to acquire negative titre spontaneously (odds ratio 11·524, 95% confidence interval 5·222-25·432; P = 0·000). We recorded that 3·2% of the patients died from haemophilia-related life-threatening bleeding.

Prevalence of FVIII Inhibitors Among Children with Hemophilia A: Experience at the Jordanian Royal Medical Services

Introduction:

Replacement therapy is constantly required by Hemophilia A (HA) patients lacking coagulation factor VIII (FVIII). The most serious complication of this treatment is the development of neutralizing antibodies (inhibitors).

Aim:

The aim of this study is to determine the frequency of FVIII inhibitors among children treated for HA at the Jordanian Royal Medical Services.

Methods:

A total of 165 diagnosed HA patients receiving on-demand treatment, were tested for FVIII inhibitors between 2003 and 2018. The age range was 6 months to 16 years. Coagulation and inhibitor screening assays were performed, followed by Bethesda assay for inhibitor-positive samples to quantify FVIII inhibitor titers.

Results:

Out of the 165 patients, 111 had severe hemophilia with FVIII level < 1%, 26 had moderate hemophilia with FVIII levels of 1–5% and 28 had mild hemophilia with FVIII levels of > 5%. Twenty patients had FVIII inhibitors, of whom 18 had high titers, 2 had low titers. The mean inhibitor level in low (titer) responders was 2.40 ± 0.85 BU, as opposed to 116.25 ±169.25 BU in high (titer) responders. In terms of disease severity, 18 of the 20 patients with FVIII inhibitors had severe HA, whereas two had moderate HA. No inhibitors were encountered in the mild HA group.

Conclusion:

Inhibitors only developed in moderate and severe cases of HA. The severity of the disease and age were the main contributing factors. The association between family history of inhibitors and the incidence of inhibitor formation warrants genetic evaluations to look for relevant mutations.

Corrigendum

[This corrects the article DOI: 10.1002/rth2.12248.].