Advances in managing rare acquired bleeding disorders

Inhibitor eradication and treatment for acquired hemophilia A

INTRODUCTION

Acquired hemophilia A (AHA) is a rare hemorrhagic autoimmune disorder characterized by autoantibodies against coagulation factor VIII (FVIII). In approximately half of the cases AHA does not recognize any cause (idiopathic form), while in the other cases it may be triggered by autoimmune disorders, cancers, drugs, infections, or pregnancy. Besides treating the underlying disorder, specific AHA treatment includes management of bleeding, if necessary, and inhibitor eradication.

AREAS COVERED

This narrative review summarizes the main epidemiological, clinical, laboratory, and therapeutic characteristics of AHA. In particular, it is focused on the current therapeutic options for the inhibitor eradication, also showing the latest findings on the innovative therapies. A literature search strategy was performed, without temporal limits, through Medline and PubMed electronic databases.

EXPERT OPINION

Various first-line and second-line immunosuppressive agents are currently available for the management of AHA. Among the latter, the anti-CD20 monoclonal antibody rituximab has been the object of intense research during the last years from investigators as innovative promising eradicating therapy for AHA. Preliminary data from the studies support the use of this drug as a first-line option for newly diagnosed AHA cases.

Innovative Therapies for Acquired Hemophilia A

Acquired hemophilia A (AHA) is a rare autoimmune bleeding disorder which can be life-threatening. AHA is due to autoantibodies against coagulation factor VIII. Disease onset may be idiopathic (approximately half of the cases) or triggered by autoimmune disorders, cancers, drugs, infections, or pregnancy. Besides treating the underlying disorder, specific AHA treatments include management of bleeding and inhibitor eradication. Various first-line and second-line hemostatic and immunosuppressive agents are currently available for the management of AHA. Recently, the hemostatic drug emicizumab and the immunosuppressive drug rituximab have been the object of intense research from investigators as innovative promising therapies for AHA. This narrative review will be focused on the current status of the clinical use of these two off-label therapeutic agents in AHA.

Investigating a Signal of Acquired Hemophilia Associated with COVID-19 Vaccination: A Systematic Case Review

Acquired hemophilia A (AHA), a rare but life-threatening disorder, most commonly occurs in older people and during pregnancy. During the coronavirus disease 2019 (COVID-19) vaccination campaign, an unexpected number of newly diagnosed AHA patients have been identified in clinical practice that were temporally related to COVID-19 vaccination. We present the result of a signal detection analysis aimed at exploring a possible association between COVID-19 immunization and occurrence of AHA. A disproportionality analysis on the World Health Organization (WHO) database was performed to investigate the presence of a signal of risk for AHA associated with COVID-19 vaccines. Reports of AHA associated with any COVID-19 vaccine included in the WHO database were then integrated with those available on the Food and Drug Administration Vaccine Adverse Events Reporting System and those published in the medical literature. The WHO database included 146 reports of AHA. The information component (IC) was significant for the association of AHA with all COVID-19 vaccines (IC025: 1.1) and with the vaccine product BNT162b2 (IC025: 1.6). After duplicate exclusion, 96 unique cases of AHA following COVID-19 vaccines have been reviewed. Median time to diagnosis was 18 days and 40% of cases documented the occurrence after the second dose. Overall, in 57% of the investigated cases, a preexisting condition predisposing to AHA was excluded. About 22% of cases occurred in subjects with age ≤65 years and there was no case associated with pregnancy. Mortality was 11%. Although we cannot exclude that the unexpected frequency of AHA diagnosis can be explained by a detection bias, the signal for COVID-19 vaccine-related AHA is robust and deserves further investigations.

Hemostasis and Thrombosis: An Overview Focusing on Associated Laboratory Testing to Diagnose and Help Manage Related Disorders

Hemostasis is a complex but balanced process that permit normal blood flow, without adverse events. Disruption of the balance may lead to bleeding or thrombotic events, and clinical interventions may be required. Hemostasis laboratories typically offer an array of tests, including routine coagulation and specialized hemostasis assays used to guide clinicians for diagnosing and managing patients. Routine assays may be used to screen patients for hemostasis-related disturbances but may also be used for drug monitoring, measuring efficacy of replacement or adjunctive therapy, and other indications, which may then be used to guide further patient management. Similarly, "specialized" assays are used for diagnostic purposes or may be used to monitor or measure efficacy of a given therapy. This chapter provides an overview of hemostasis and thrombosis, with a focus on laboratory testing that may be used to diagnose and help manage patients suspected of hemostasis- and thrombosis-related disorders.