PB0240 - The role of anti-emicizumab antibodies and their clinical relevance

Sunday, June 23, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Co-Author(s)

CV

Carla Valsecchi

Researcher
Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
Milan, Lombardia, Italy
LS

Lucia Schiavone

Researcher
Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
Roberta Gualtierotti, PhD

Associate Professor
Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy; Università degli Studi di Milano, Department of Pathophysiology and Transplantation, Milan, Italy
Milan, Lombardia, Italy

Presenting Author(s)

Sara Arcudi, MD, PhD

Clinician
Foundation I.R.C.C.S. Ca’ Granda, Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy

Co-Author(s)

Alessandro Ciavarella

Clinician
Fondazione IRCCS Ca’Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
SS

Simona Maria Siboni

Physician
Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center
Milan, Lombardia, Italy
CN

Cristina Novembrino

Biologist
Fondazione IRCCS Ca’Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Milan, Italy
Milan, Lombardia, Italy
Flora Peyvandi, MD, PhD

Full Professor
Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Università degli Studi di Milano, Department of Pathophysiology and Transplantation
Milan, Lombardia, Italy

Background: The development of anti-drug antibodies (ADAs) in patients treated with emicizumab is a rare event. ADAs can be transient, without clinical significance, or can dramatically influence the therapeutic response. Their clinical implications are not fully clarified. ADAs detection is complicated by the presence of circulating drug.

Aims: To describe the prevalence of anti-emicizumab antibodies and their clinical relevance in the Milan cohort.

Methods: 70 children and adults affected with haemophilia A, with and without FVIII inhibitor, have been switched to emicizumab at the Haemophilia and Thrombosis Center in Milan.
Clinical information including events of spontaneous bleeding were collected; laboratory evaluation such as aPTT, emicizumab levels, and ADAs detection were performed at several time points and when patient had bleeding symptoms.

Results: Four out of seventy (5.7%) studied patients, developed ADAs with reduced emicizumab levels (Table 1 and Figure 1).
ADAs have been developed at different exposure days, from 4 to >200. No correlation was observed between ADAs and bleeding symptoms.
The minimum level of emicizumab reported was 17µg/mL with no bleeding symptoms. No correlation between emicizumab level and bleeding events was found.

Conclusion(s): Our experience confirms that there is no need of a regular detection of the anti-emicizumab antibodies in patients with no bleeding. Moreover, in our cohort we found no correlation between clinical manifestations and emicizumab levels, at least with emicizumab concentration >17µg/mL.
Further investigation, as aPTT, emicizumab concentration and anti-drug antibodies, should be reserved only in patients with loss of drug efficacy or bleeding symptoms.