Background: Hemophilia concentrates’ pharmacokinetics (PKs) have important variability between patients, for this reason standard doses often result far from goal plasmatic concentrations. Prophylactic treatment efficacy, which has become the gold-standard in patients with moderate or severe hemophilia, is based on plasmatic concentrations which depends on several variables: genotype, fenotype, bleeding events (intensity, location, frequency), lifestyle, age, weight and physical activity, among others. PK-guided approach is necessary in these patients to personalize each treatment.

Aims: Clinical and pharmacokinetic assessment of hemophilia B patients with prophylactic treatment, who have been switched from standard recombinant products (SHL) to extend half-life recombinant factors (EHL).

Methods: PKs were assessed in four hemophilia B patients with prophylactic treatment based on SHL who were switched in December 2020 to EHL factors. Data was collected from medical records and PK software, results were compared to prior prophylaxis regimen.

Results:

The patients, all males, three diagnosed with severe and one with moderate hemophilia B had been receiving infusions of  SHL productos, mean doses of 40 UI/kg twice a week, and with trough levels from 2 to 5%. After switching to EHL factors through levels achieved were from 5 to 12% with doses of 35-50 UI/kg each week or each two weeks. However, all patients had joint bleeding and ache after switching.

Patient 1

Patient 2

Conclusions: Switch to EHL was associated with an improvement in PK profile and dosification without improving clinical outcome. These results raised questions about the convenience of PK-guided approaches in these treatments.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/clinical-and-pharmacokinetic-assessment-after-switching-to-an-extended-half-life-product-for-prophylaxis-in-haemophilia-b/