Bioequivalence of recombinant factor VIII products: a position paper from the Italian Association of Hemophilia Centers

Over the last three decades, the continuous evolution of recombinant factor VIII (rFVIII) concentrates for replacement treatment of hemophilia A, including recent extended half-life products, implies that patients may switch from one product to another, technologically more advanced, with the aim of improving treatment efficacy, safety, management and, ultimately, quality of life. In this scenario, the issues of bioequivalence of rFVIII products and the clinical implications of their interchangeability are keenly debated, in particular when economic reasons or purchasing systems influence product availability and choices. Although sharing the same Anatomical Therapeutic Chemical (ATC) level, rFVIII concentrates, as other biological products, show relevant differences in terms of molecular structure, source and manufacturing process, which make them unique products, recognized as new active substances by regulatory agencies. Moreover, data from clinical trials with both standard and extended half-life products clearly document the large inter-patient variability of pharmacokinetic profiles after administering the same dose of the same product; in cross-over evaluations, even when mean values are comparable, some patients show better patterns with one product or with the comparator one. Pharmacokinetic assessment thus reflects the response to a specific product in the individual patient, with his genetic determinants, only partially identified, affecting the behavior of exogenous FVIII. These concepts, consistent with the currently recommended approach of personalization of prophylaxis, are discussed in this position paper endorsed by the Italian Association of Hemophilia Centers (AICE), highlighting that ATC or other available classifications do not completely consider differences between drugs and innovations and that substitutions of rFVIII products will not invariably ensure the previously achieved clinical outcomes or generate benefits for all patients.

Acquired haemophilia A: Italian Consensus Recommendations on diagnosis, general management and treatment of bleeding

BACKGROUND

Acquired haemophilia A (AHA) is a rare bleeding disorder due to autoantibodies to coagulation factor VIII that may be secondary to autoimmune diseases, cancer, drugs, pregnancy, infections, or be idiopathic. Recurrent bleeding, often severe, mostly in muscles and soft tissues, and isolated prolonged activated partial thromboplastin time (aPTT), in the absence of personal and family history of bleeding, are typical features that should raise the suspicion of AHA. Poor awareness of the disease results in diagnostic delays and inappropriate treatment.

MATERIALS AND METHODS

The Italian Association of Haemophilia Centres (AICE) developed consensus recommendations in cooperation with the Italian Society on Thrombosis and Haemostasis (SISET). The document was shared with scientific societies of specialist physicians, laboratory professionals and pharmacists to spread knowledge about AHA and promote appropriate diagnosis/treatment.

RESULTS

Ready availability of the aPTT mixing test is crucial, although diagnostic confirmation and optimal management require prompt referral of patients to specialised centres with rapidly available diagnostic and therapeutic facilities. If immediate referral is unfeasible, treatment must be undertaken early, under guidance of specialised centres or based on shared protocols. Recommendations about diagnosis, general management and, in bleeding patients, haemostatic therapy using bypassing agents or replacement treatment, including the recently available recombinant porcine factor VIII, are provided, considering the different clinical settings and laboratory facilities.

DISCUSSION

This consensus document aims to improve the overall healthcare pathways for AHA, harmonise the management and therapeutic approaches to newly diagnosed patients and reduce the still relevant complications and mortality in this setting.

Apixaban and eftrenonacog alfa treatment in a patient with moderate hemophilia B and cardiovascular disease

In developed countries, the life expectancy of patients with hemophilia (PwH) is now close to that of the unaffected male population. This means that these patients are at risk of developing age-related comorbidities, including cardiovascular disease. Managing cardiovascular disease in PwH patients can be particularly challenging, due to their high bleeding risk. To our knowledge, this is the first report of a male patient with moderate hemophilia B and hypertensive ischemic heart disease complicated by arrhythmia due to nonvalvular atrial fibrillation, who was treated with apixaban and left atrial appendage closure while receiving concomitant anti-hemorrhagic prophylaxis with eftrenonacog alfa.

Management of patients with severe haemophilia a without inhibitors on prophylaxis with emicizumab: AICE recommendations with focus on emergency in collaboration with SIBioC, SIMEU, SIMEUP, SIPMeL and SISET

INTRODUCTION

The factor VIII (FVIII)-mimetic bispecific monoclonal antibody, emicizumab, previously approved for prophylaxis in haemophilia A with inhibitors, has been recently licensed in several countries also in patients with severe haemophilia A (PWSHA) without inhibitors. The introduction of this innovative agent requires the development of specific pathways at Haemophilia Treatment Centres (HTC), particularly regarding laboratory testing and treatment of breakthrough bleeds and invasive procedures/surgeries, even more critical when patients are managed by non-specialist professionals. Limited literature data and clinical experience in PWSHA without inhibitors on emicizumab are currently available.

AIM

To promote awareness and overcome these challenges, the Italian Association of Haemophilia Centres (AICE) issued a guidance on the management of PWSHA without inhibitors on emicizumab prophylaxis, focused on emergency and shared with other National Scientific Societies in the field.

METHODS

The document, drafted by an AICE expert panel and approved through online consultation, was further revised by a multidisciplinary working group, including members of 5 haemostasis, laboratory and emergency scientific societies. The final version was approved by the Council of each society.

RESULTS

General recommendations about use of FVIII concentrates for the treatment of bleeding or haemostatic coverage of invasive procedures/surgeries and laboratory monitoring in PWSHA without inhibitors on emicizumab are provided. Specific issues of the management in the emergency room are focused, highlighting the need for direct involvement or formalized supervision by specialist HTC physicians.

CONCLUSIONS

This guidance provides a reference pathway to be implemented in the different healthcare organizations, especially for the challenging emergency management in this setting.

Effect of chronic ethanol administration on production of and response to erythropoietin in the mouse

Male adult mice were allowed to drink only a solution of 32% ethyl alcohol for 3 months. Hematocrit and hemoglobin concentration were lower in ethanol-treated than in control mice at the end of the experimental period. Red cell volume was not significantly different between both groups. Plasma volume was higher in experimental than in control mice. Therefore, the anemia found in ethanol-treated mice can be regarded as a dilution anemia. When ethanol-treated and control mice, both made polycythemic by hypertransfusion to suppress their endogenous erythropoietin formation, were injected with doses of erythropoietin in the range of 0.2 to 3.2 IRP units, the derived dose-response curves were markedly different because of a reduced response to the hormone by the treated mice. This finding suggests that the number of "erythropoietin-responsive cells" may be reduced as the result of ethanol, or that their response to the hormone may be delayed or inhibited. Plasma erythropoietin concentration in alcohol- treated mice, as determined in the posthypoxic polycythemic mouse bioassay, was higher than normal in both normoxic and hypoxic conditions, probably as the result of the impaired responsiveness to the hormone mentioned above.