Monoclonal Antibodies Capable of Inhibiting Complement Downstream of C5 in Multiple Species

Abstract

Better understanding of roles of complement in pathology has fuelled an explosion of interest in complement-targeted therapeutics. The C5-blocking monoclonal antibody (mAb) eculizumab, the first of the new wave of complement blocking drugs, was FDA approved for treatment of Paroxysmal Nocturnal Hemoglobinuria in 2007; its expansion into other diseases has been slow and remains restricted to rare and ultra-rare diseases such as atypical hemolytic uremic syndrome. The success of eculizumab has provoked other Pharma to follow this well-trodden track and made C5 blockade the busiest area of complement drug development. C5 blockade inhibits generation of C5a and C5b, the former an anaphylatoxin, the latter the nidus for formation of the pro-inflammatory membrane attack complex. In order to use anti-complement drugs in common complement-driven diseases, more affordable and equally effective therapeutics are needed. To address this, we explored complement inhibition downstream of C5. Novel blocking mAbs targeting C7 and/or the C5b-7 complex were generated, identified using high throughput functional assays and specificity confirmed by immunochemical assays and surface plasmon resonance (SPR). Selected mAbs were tested in rodents to characterize pharmacokinetics, and therapeutic capacity. Administration of a mouse C7-selective mAb to wildtype mice, or a human C7 specific mAb to C7-deficient mice reconstituted with human C7, completely inhibited serum lytic activity for >48 h. The C5b-7 complex selective mAb 2H2, most active in rat serum, efficiently inhibited serum lytic activity in vivo for over a week from a single low dose (10 mg/kg); this mAb effectively blocked disease and protected muscle endplates from destruction in a rat myasthenia model. Targeting C7 and C7-containing terminal pathway intermediates is an innovative therapeutic approach, allowing lower drug dose and lower product cost, that will facilitate the expansion of complement therapeutics to common diseases.

Novel Selection Approaches to Identify Antibodies Targeting Neoepitopes on the C5b6 Intermediate Complex to Inhibit Membrane Attack Complex Formation

“…Previous examples of antibody discovery approaches for complement neoepitopes include phage display (S77) or mouse immunization (H17) [16,33]. More recently, a study by Zelek and Morgan (2020), provided validation of the lower dosing implications of targeting an epitope of an active intermediate terminal pathway complex (C5b7) with identification of an antibody using an in vivo approach [34].…”

Comparative efficacy of the original and biosimilar eculizumab in the treatment of obstetric atypical hemolytic-uremic syndrome

“…Клинико-лабораторные проявления ТМА также не различались между двумя группами в острый период заболевания, хотя у пациенток, получавших биоаналог экулизумаба, исходно отмечались несколько более выраженный гемолиз (активность ЛДГ, количество шизоцитов и содержание гаптоглобина) и большее число пораженных органов. В обеих группах более 80% пациенток достигли полного восстановления функции почек, при этом частота благоприятного почечного исхода у пациенток, получавших Элизарию, оказалась даже недостоверно выше, чем в группе женщин, которым проводилась терапия оригинальным экулизумабом (88,9% и 80,5%, соответственно), в то время как доля женщин, оставшихся на диализе, была сопоставимой в двух группах (11, Немаловажное значение имеет более низкая стоимость Элизарии (примерно на 20%) по сравнению с Солирисом, который сегодня остается одним из самых дорогих препаратов в мире [22].…”

Terminal complement pathway activation drives synaptic loss in Alzheimer’s disease models

“…The assay, like the widely used human TCC assays, measures both the fluid-phase product of terminal pathway activation, sC5b-9, and the membrane-inserted MAC; the term TCC encompasses both complexes. Plates were coated with rabbit anti-rat/mouse C9 (10 µg/ml) [ 39 , 40 ] and blocked in BSA (3% w/v) -PBS-T. Standard curves were generated starting at 1:3 activated mouse serum then double-diluting in BSA (0.3% w/v) -PBS-T-EDTA (Additional file 1 : Fig. S1c).…”