Immune tolerance induction for treating inhibitors in people with congenital haemophilia A or B

Inhibitors: A Need for Eradication?

The development of inhibitors against factor VIII (FVIII) concentrates represents a significant treatment complication for hemophilia. Immune tolerance induction (ITI) therapy eradicates inhibitors in 60-80% of patients, resulting in a normal FVIII response. This article, based on presentations at the 6th International Coagulation Meeting, held in Barcelona, Spain, in September 2017, provides an overview of management approaches for patients with inhibitors and briefly tabulates four cases of ITI therapy (first-line or rescue ITI therapy in pediatric and adult patients) with successful outcomes. Switching FVIII product from recombinant FVIII to plasma-derived FVIII/VWF concentrate may be helpful in eradicating inhibitors. The rate of decline of inhibitor titer in the initial stages of ITI therapy is a good indicator of the success or failure of therapy, although prognostic biomarkers are needed. The development of the bispecific monoclonal antibody emicizumab, which was recently shown to reduce bleeding in inhibitor patients, offers a potential alternative therapeutic option. However, the benefits of inhibitor eradication, including a wider choice of cheaper therapeutic products for preventing and treating bleeds, suggest that at least one attempt of ITI therapy should be offered to patients who develop inhibitors.

Economic analysis of not running tenders for recombinant Factor VIII procurement: a simplified analysis to estimate an otherwise unknown pharmacoeconomic index

Background

Two approaches to the procurement of recombinant Factor VIII products are used by health systems: (A) the most common approach where acquisition tenders are not carried out; (B) the approach tested in the UK in which procurement is based on tenders. The respective cost-effectiveness is not known.

Objective

To estimate the incremental cost-effectiveness ratio (ICER) for the comparison A vs B.

Methods

The analysis evaluated: (i) Factor VIII cost with/without tenders; (ii) inhibitor development caused by switching between products; (iii) clinical and economic consequences of inhibitors. Information on these items was obtained from a literature search. Because of the scarce evidence available on some items, our analysis considered the 'most favourable' scenario-that is, some extreme though reasonable assumptions were adopted that were intentionally biased towards improving the ICER of the no-tender option.

Results and discussion

We estimated an ICER for A vs B of £486 409 (€657 139; £1=€1.351) per quality-adjusted life year (QALY). Since pharmacoeconomic thresholds are ∼£30 000 per QALY, our results indicate that the cost-effectiveness of acquisition strategies that avoid tenders is prohibitive. Because of the simplified nature of our analysis, this estimate is preliminary.

Conclusions

The 'true' ICER of A vs B remains unknown, but its value is likely to be even worse than the unfavourable ICER of £486 409 (€657 139) per QALY.

Recombinant factor VIIa concentrate versus plasma-derived concentrates for treating acute bleeding episodes in people with haemophilia and inhibitors

BACKGROUND

In people with haemophilia, therapeutic clotting agents might be recognised as a foreign protein and induce anti-factor VIII antibodies, known as 'inhibitors'. Drugs insensitive to such antibodies, either recombinant or plasma-derived, are called factor VIII 'by-passing' agents and used for treatment of bleeding in people with inhibitors.

OBJECTIVES

To determine the clinical effectiveness of recombinant factor VIIa concentrate compared to plasma-derived concentrates for treating acute bleeding episodes in people with haemophilia and inhibitors.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Coagulopathies Trials Register which comprises references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search of the Group's Coagulopathies Trials Register: 23 September 2015.

SELECTION CRITERIA

Randomised and quasi-randomised controlled clinical trials comparing recombinant factor VIIa concentrate to human plasma-derived concentrates (high-dose human or recombinant factor VIII or factor IX concentrate; non-activated prothrombin complex concentrates; activated prothrombin complex concentrates) in people with haemophilia. Comparisons with animal-derived products were excluded.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the trials (eligibility and risk of bias) and extracted data. No combined meta-analyses were performed due to the unavailability of outcomes and comparisons common to the included trials.

MAIN RESULTS

A total of 15 trials were identified, two of which (with data for a total of 69 participants) were eligible for analysis. Both trials showed methodological flaws and did not show superiority of one treatment over the other. Both the treatments showed that recombinant factor VIIa and activated prothrombin complex concentrate appeared to have a similar haemostatic effect in both trials, without increasing thromboembolic risk.

AUTHORS' CONCLUSIONS

Based on the separate analysis of the two available randomised trials, recombinant factor VIIa and activated prothrombin complex concentrate were found to be similar in efficacy and safety. However, there is a need for further, well-designed, adequately-powered, randomised controlled trials to assess the relative benefits and risks of using recombinant factor VIIa compared to human plasma-derived concentrates in people with haemophilia with inhibitors. It is advisable that researchers in the field define commonly agreed objective outcome measures in order to enable the pooling of their results, thus increasing the power of comparisons. To date, data could not be combined in a formal meta-analysis. For the same reason reporting concordant and discordant pairs in cross-over trials is recommended.