Periodic Reporting for period 2 - ATAC (Antibody therapy against coronavirus (COVID-19))
Période du rapport: 2021-04-01 au 2022-07-31
The emergence and spread of the novel human severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of the coronavirus disease 2019 (COVID-19), has led to a pandemic with major consequences on global health and world economy. Passive immunization with antibodies has proven to be highly efficient for treatment and prevention of infectious human diseases. The immunoglobulin preparation used for passive immunization is generally purified from human plasma with high titers against the microorganisms but may also include human monoclonal antibodies isolated from B cells. Passive immunization using plasma, polyclonal or monoclonal antibodies from convalescent blood of COVID-19 infected donors has therefore a strong potential to reduce the mortality rate in infected people.
The ATAC (Antibody Therapy Against Coronavirus) project is a 40 months project that falls into the topic “SC1-PHE-CORONAVIRUS-2020: Advancing knowledge for the clinical and public health response to the COVID-19 epidemic” of the Horizon 2020 Health work program. The project is coordinated by Karolinska Institutet (Stockholm, Sweden), and includes the Institute for Research in Biomedicine (Bellinzona, Switzerland), the Joint Research Centre of the European Commission (Brussels, Belgium), Technische Universitaet Braunschweig (Braunschweig, Germany) and Fondazione IRCCS Policlinico San Matteo (Pavia, Italy).
The project aims at developing a human antibody therapy against COVID-19. The specific objectives and achievements of ATAC includes:
• Rapid development of antibody therapy (passive immunization) based on human plasma containing high titers neutralizing antibodies derived from COVID-19 convalescent donors
• Discovery, characterization, pre-clinical and clinical development of human monoclonal antibodies against COVID-19
• Rapid dissemination of the results to help respond to the emergency
• Acquire an understanding of the neutralization of COVID-19 by human monoclonal and serum antibodies to counteract future epidemics
More specifically, the work of the ATAC consortium includes: obtain blood samples from coronavirus (CoV) convalescent human donors; isolate human antibodies with three independent strategies (hyperimmune plasma, monoclonal antibodies from B cells and phage library); select, characterize and optimize lead candidate monoclonal antibodies for preclinical and clinical development through a combination of high-throughput screening, rapid experimental work and computational analysis; consult with EMA to ensure that regulatory aspects are embedded right from the start.
The ATAC (Antibody Therapy Against Coronavirus) project is a 40 months project that falls into the topic “SC1-PHE-CORONAVIRUS-2020: Advancing knowledge for the clinical and public health response to the COVID-19 epidemic” of the Horizon 2020 Health work program. The project is coordinated by Karolinska Institutet (Stockholm, Sweden), and includes the Institute for Research in Biomedicine (Bellinzona, Switzerland), the Joint Research Centre of the European Commission (Brussels, Belgium), Technische Universitaet Braunschweig (Braunschweig, Germany) and Fondazione IRCCS Policlinico San Matteo (Pavia, Italy).
The project aims at developing a human antibody therapy against COVID-19. The specific objectives and achievements of ATAC includes:
• Rapid development of antibody therapy (passive immunization) based on human plasma containing high titers neutralizing antibodies derived from COVID-19 convalescent donors
• Discovery, characterization, pre-clinical and clinical development of human monoclonal antibodies against COVID-19
• Rapid dissemination of the results to help respond to the emergency
• Acquire an understanding of the neutralization of COVID-19 by human monoclonal and serum antibodies to counteract future epidemics
More specifically, the work of the ATAC consortium includes: obtain blood samples from coronavirus (CoV) convalescent human donors; isolate human antibodies with three independent strategies (hyperimmune plasma, monoclonal antibodies from B cells and phage library); select, characterize and optimize lead candidate monoclonal antibodies for preclinical and clinical development through a combination of high-throughput screening, rapid experimental work and computational analysis; consult with EMA to ensure that regulatory aspects are embedded right from the start.
Plasma therapy for treatment of COVID-19 patients:
We have identified factors, including time after infection, age, severity of COVID-19, vaccination, that are positively associated with higher neutralizing antibody titers at the time of donation which may help to optimize the selection of hyperimmune convalescent plasma donors for plasma therapy. We have also assessed the early use of hyperimmune plasma for the treatment of COVID-19 patients needing non-invasive or invasive mechanical ventilation. Preliminary analyses of results showed that treatment with hyperimmune plasma reduced mortality in patients hospitalized in intensive care unit.
Isolation of monoclonal antibodies to SARS-CoV-2 using purification of B cells and phage display:
The consortium has identified the first lead monoclonal antibody candidates with exceptional neutralizing activity within less than 6 months. The antibody STE73-2E9 isolated from a naive phage library was neutralizing and showed an IC50 of 0,41nM in a plaque-reduction neutralization assay (Bertoglio et al. 2021, Nature Communication). Two reports on the discovery and characterization of human monoclonal antibodies (C121, C144 and C135) were published (Robbiani et al. 2020, Nature 2020; Gaebler et al. 2021, Nature). Three antibodies (C121, C144 and C135) binding to three distinct epitopes on the SARS-CoV-2 spike receptor binding domain (RBD) and neutralizing the virus with half-maximal inhibitory concentrations (IC50 values) as low as 2 ng ml−1 were isolated from convalescent patients (Robbiani et al. 2020, Nature). More recently broadly neutralizing antibodies targeting conserved region on the spike protein were isolated and were shown to neutralize Omicron subvariants.
Characterization and engineering of therapeutic antibodies:
Using recombinant protein antigens from SARS-CoV-2, the binding properties of monoclonal antibodies were extensively characterized including binding affinity, epitope mapping, and neutralization. Based on the lead antibody candidates C121 and C135 (Robbiani et al. 2020, Nature), a bispecific antibody, named CoV-X2, that simultaneously binds two independent sites on the RBD was engineered and neutralizes the G614 virus variant in cell culture assays and in animal models without detection of escape mutants (DeGasparo et al. 2021, Nature). More recently, a bispecific antibody, CoV-X4042, combining two antibody targeting conserved regions on the spike protein, was able to neutralize all variants of concern, from the original virus to the currently circulating Omicron BA.5. The bispecific antibody was shown to protect animals against SARS-CoV-2 challenge and will be tested in a phase I trial within one year.
Dissemination and exploitation of results:
Besides providing lead human antibody candidates for therapy, ATAC rapidly disseminated results to help respond to the current COVID-19 epidemic. More than 40 papers were published during the first 27 months of the project, including publications with a high impact factor. The project and results received important coverage on tv, radio, press, social media and were amply discussed by the general public in online blogs. The publications and related news were posted on the ATAC public-access website (https://covidantibodytherapy.info/) Twitter account (@atac76312929) and the LinkedIn profile (https://www.linkedin.com/in/atac-project-0aa1951aa/). Furthermore, a patent on the bispecific antibody was published (PCT/EP2020/085342).
We have identified factors, including time after infection, age, severity of COVID-19, vaccination, that are positively associated with higher neutralizing antibody titers at the time of donation which may help to optimize the selection of hyperimmune convalescent plasma donors for plasma therapy. We have also assessed the early use of hyperimmune plasma for the treatment of COVID-19 patients needing non-invasive or invasive mechanical ventilation. Preliminary analyses of results showed that treatment with hyperimmune plasma reduced mortality in patients hospitalized in intensive care unit.
Isolation of monoclonal antibodies to SARS-CoV-2 using purification of B cells and phage display:
The consortium has identified the first lead monoclonal antibody candidates with exceptional neutralizing activity within less than 6 months. The antibody STE73-2E9 isolated from a naive phage library was neutralizing and showed an IC50 of 0,41nM in a plaque-reduction neutralization assay (Bertoglio et al. 2021, Nature Communication). Two reports on the discovery and characterization of human monoclonal antibodies (C121, C144 and C135) were published (Robbiani et al. 2020, Nature 2020; Gaebler et al. 2021, Nature). Three antibodies (C121, C144 and C135) binding to three distinct epitopes on the SARS-CoV-2 spike receptor binding domain (RBD) and neutralizing the virus with half-maximal inhibitory concentrations (IC50 values) as low as 2 ng ml−1 were isolated from convalescent patients (Robbiani et al. 2020, Nature). More recently broadly neutralizing antibodies targeting conserved region on the spike protein were isolated and were shown to neutralize Omicron subvariants.
Characterization and engineering of therapeutic antibodies:
Using recombinant protein antigens from SARS-CoV-2, the binding properties of monoclonal antibodies were extensively characterized including binding affinity, epitope mapping, and neutralization. Based on the lead antibody candidates C121 and C135 (Robbiani et al. 2020, Nature), a bispecific antibody, named CoV-X2, that simultaneously binds two independent sites on the RBD was engineered and neutralizes the G614 virus variant in cell culture assays and in animal models without detection of escape mutants (DeGasparo et al. 2021, Nature). More recently, a bispecific antibody, CoV-X4042, combining two antibody targeting conserved regions on the spike protein, was able to neutralize all variants of concern, from the original virus to the currently circulating Omicron BA.5. The bispecific antibody was shown to protect animals against SARS-CoV-2 challenge and will be tested in a phase I trial within one year.
Dissemination and exploitation of results:
Besides providing lead human antibody candidates for therapy, ATAC rapidly disseminated results to help respond to the current COVID-19 epidemic. More than 40 papers were published during the first 27 months of the project, including publications with a high impact factor. The project and results received important coverage on tv, radio, press, social media and were amply discussed by the general public in online blogs. The publications and related news were posted on the ATAC public-access website (https://covidantibodytherapy.info/) Twitter account (@atac76312929) and the LinkedIn profile (https://www.linkedin.com/in/atac-project-0aa1951aa/). Furthermore, a patent on the bispecific antibody was published (PCT/EP2020/085342).
Our study contributed to set the basis for choosing the best timing and patients characteristics for the collection of plasma from hyperimmune convalescent patients for plasma therapy. Furthermore we showed that plasma therapy could be a promising approach for treatment of COVID-19 patients if administered at early stage of the disease.
The most potent neutralizing monoclonal antibodies discovered to date may lead to virus escape and work was performed to identify antibodies that in addition to being potent virus neutralizers are also capable to neutralize multiple variants of the virus, which are of great concern because of enhanced transmissibility. The engineered bispecific antibody, CoV-X4042, shown to be efficient in preclinical studies including against Omicron, is planned to be scaled-up under GMP conditions to obtain clinical-grade material. Once the toxicology studies confirm suitability, we will perform a phase I clinical trial. Such antibodies could be used individually or as a cocktail of multiple antibodies for passive protection in either prophylaxis for at-risk populations (patients under immunosuppressive therapy or immunocompromised) or for treatment against current or future outbreaks of COVID-19 or related coronavirus.
The most potent neutralizing monoclonal antibodies discovered to date may lead to virus escape and work was performed to identify antibodies that in addition to being potent virus neutralizers are also capable to neutralize multiple variants of the virus, which are of great concern because of enhanced transmissibility. The engineered bispecific antibody, CoV-X4042, shown to be efficient in preclinical studies including against Omicron, is planned to be scaled-up under GMP conditions to obtain clinical-grade material. Once the toxicology studies confirm suitability, we will perform a phase I clinical trial. Such antibodies could be used individually or as a cocktail of multiple antibodies for passive protection in either prophylaxis for at-risk populations (patients under immunosuppressive therapy or immunocompromised) or for treatment against current or future outbreaks of COVID-19 or related coronavirus.