Abstract Background Miridesap depletes circulating serum amyloid P (SAP) and dezamizumab (anti-SAP monoclonal antibody) targets SAP on amyloid deposits, triggering amyloid removal. In a phase 1, first-in-human study (FIHS), progressive amyloid removal was observed in some patients after ≤ 3 cycles of miridesap/dezamizumab. Methods This observational, non-interventional study in patients who received miridesap/dezamizumab during the FIHS (planned follow-up: 5 years) evaluated response to treatment based on routine assessments of disease status and key organ function. In a post hoc analysis, patients responding to treatment in the FIHS during follow-up were identified as responders and further categorized as sustained or declining responders. Results In the FIHS, 17/23 patients were treatment responders. Of these patients, seven (immunoglobulin light chain [AL], n = 6; serum amyloid A, n = 1) were considered sustained responders and ten (fibrinogen-a alpha chain [AFib], n = 5; AL, n = 4; apolipoprotein A-I, n = 1) were considered declining responders. We primarily present responder patient-level data for functional, cardiac, laboratory and imaging assessments conducted during the follow-up period, with non-responder data presented as supplementary. Conclusion No further development of miridesap/dezamizumab is planned in amyloidosis. However, long-term follow-up of these patients may provide insight into whether active removal of amyloid deposits has an impact on disease progression. Trial registration ClinicalTrials.gov, NCT01777243. Registered 28 January 2013, https://clinicaltrials.gov/ct2/show/study/NCT01777243.
Orphanet journal of rare diseases
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