Ensovibep, a novel trispecific DARPin candidate that protects against SARS-CoV-2 variants

Abstract

The SARS-CoV-2 virus responsible for the COVID-19 pandemic has so far infected more than 100 million people globally, and continues to undergo genomic evolution. Emerging SARS-CoV-2 variants show increased infectivity and may lead to resistance against immune responses of previously immunized individuals or existing therapeutics, especially antibody-based therapies. Several monoclonal antibody therapeutics authorized for emergency use or in development start to lose potency against various SARS-CoV-2 variants. Cocktails of two different monoclonal antibodies constitute a promising approach to protect against such variants as long as both antibodies are potent, but come with increased development complexity and therefore cost. As an alternative, we developed two multi-specific DARPin® therapeutics, each combining three independent DARPin® domains binding the SARS-CoV-2 spike protein in one molecule, to potently neutralize the virus and overcome virus escape. Here, we show in a panel of in vitro studies that both multi-specific DARPin® therapeutics, ensovibep (MP0420) and MP0423, are highly potent against the new circulating SARS-CoV-2 variants B.1.1.7 (UK variant) and B.1.351 (South African variant) and the most frequent emerging mutations in the spike protein. Additionally, viral passaging experiments show potent protection by ensovibep and MP0423 against development of escape mutations. Furthermore, we demonstrate that the cooperative binding of the individual modules in a multi-specific DARPin® antiviral is key for potent virus inhibition and protection from escape variants. These results, combined with the relatively small size and high production yields of DARPin® molecules, suggests ensovibep and MP0423 as superior alternatives to monoclonal antibody cocktails for global supply and demonstrate the strength of the DARPin® platform for achieving potent and lasting virus inhibition for SARS-CoV-2 and possibly other viruses.

B.1.526 SARS-CoV-2 variants identified in New York City are neutralized by vaccine-elicited and therapeutic monoclonal antibodies

“…Our results showed that REGN10987, which binds to the side of the RBD [25,31], maintains potent neutralizing activity against both versions of B.1.526 but that REGN10933, which binds to the top face of the RBD that interacts with ACE2, loses 12fold of its potency against the E484K version. The decrease in neutralizing titer was caused by the E484K mutation and is similar to the previously reported loss of titer against B.1.351 which also bears the mutation [24][25][26][27][28][32][33][34]. Despite the partial loss of activity by REGN10933 against B.1.526, the neutralizing activity of the combined antibody cocktail remained high.…”

“…Previous studies have shown that the E484K in the B.1.351 spike protein leads to a degree of resistance to neutralization by both infection-and vaccine-elicited antibodies as well as to the REGN10933 therapeutic monoclonal antibody [24][25][26][27]. Moreover, the B.1.351 variant spike protein has been found to reduce the level of protection provided by vaccination in populations in which the variant has become prevalent [24,28].…”

Highly potent anti-SARS-CoV-2 multivalent DARPin therapeutic candidates

“…The multivalent DARPin molecules are expected to retain potency even if the spike protein of SARS-CoV-2 should mutate considerably in the future, especially when multiple modes of action are addressed. Evaluation of the impact of a panel of reported mutations in the SARS-CoV-2 spike protein revealed no loss of neutralizing capacity of our lead candidates in a PsV NA and a set of emerging variants and spike protein mutations were recently reported elsewhere( 42 ). Although it remains to be determined if additional mutations will impact the neutralization potencies of the multivalent DARPin molecules, we expect multivalent DARPin molecules to retain high potency in case the SARS-CoV-2 spike protein should mutate in the future.…”

An update on novel approaches for diagnosis and treatment of SARS-CoV-2 infection

“…have developed mono and multi-DARPins against spike protein of SARS-CoV-2 and in vivo studies on hamster showed significant reduction of virus pathogenesis [ 77 ]. Multi-DARPin molecules including MP0420 and MP0423, combining of three independent DARPin domains, binding specifically to SARS-CoV-2 RBD or other part of spike protein respectively, are designed of which the efficacy of ensovibep (MP0420) is under investigation in a clinical trial [ 63 , 70 , 78 ]. In vitro studies showed that these two multi-DARPins are highly potent against the new circulating SARS-CoV-2 variants including UK variant (B.1.1.7) and South African variant (B.1.351) [ 78 ].…”