REGN 3051 is a fully human spike-protein blocking monoclonal antibody, under development by Regeneron Pharmaceuticals, for the treatment of Middle East respiratory syndrome coronavirus (MERS-CoV). This antibody has an ability to reduce virus titres as well as ameliorate virus induced lung pathology when given post infection. The company is using its VelociGene® and VelocImmune® rapid response technologies. VelocImmune® is used for the rapid generation of fully human monoclonal antibodies, allowing creation of a panel of antibodies that inhibit interaction between the MERS coronavirus spike protein and its receptor, DPP4, thereby preventing virus cell entry. VelociGene® is a large-scale mouse genomic modification platform and was utilised to create a genetically humanised disease model for the MERS infection. Phase I development is underway in the US.
Regeneron Pharmaceuticals is also developing REGN 3048, another spike protein blocking antibody that binds to different epitope of the protein, for the treatment of MERS-CoV [see AdisInsight drug profile 800042890].
Further work on the MERS antibodies is being undertaken by Regeneron in collaboration with the Biomedical Advanced Research and Development Authority. The University of Maryland School of Medicine provided access to an infectious MERS clone and conducted studies with the live virus  .
In August 2016, Regeneron entered into an agreement with the Biomedical Advanced Research and Development Authority (BARDA) of the US Department of Health and Human Services (HHS) to manufacture and study two antibody therapies for the potential prevention and treatment of Middle East Respiratory Syndrome (MERS). Under the terms of the agreement, HHS will provide initial funding of approximately $US8.9 million to support packaging and labelling of the antibodies for human use, the preparation and submission of an IND application with the US FDA and a National Institutes of Health-conducted clinical trial in healthy volunteers. 
Regeneron reported that the MERS antibodies have been discovered and developed pursuant to Regeneron's antibody discovery and preclinical development agreement with Sanofi and are subject to Sanofi's opt-in rights for development and commercialisation  .
Key Development Milestones
In February 2018, National Institute of Allergy and Infectious Diseases initiated a first-in-human phase I trial to assess the safety, tolerability, pharmacokinetics and immunogenicity of single ascending doses of REGN 3048 co-administered with REGN 3051, in healthy volunteers (15-0109; HHSN272201500005I; NCT03301090). The randomised, double-masking, placebo controlled trial will enrol approximately 48 patients in the US.
In February 2016, Regeneron Pharmaceuticals' patents EP(UK) 1 360 287 and EP(UK) 2 264 163 covering its VelocImmune® propriety technology were revoked by the English High Court upon invalidity claims filed by Kymab. The patents covered genetically modified mice containing human antibody variable region loci and humanised antibodies from such mice  .