SK’s COVID-19 vaccine candidate has secured promising interim data from a Phase I/II clinical trial. A Phase III clinical trial will begin in tandem with the vaccine candidate’s heightened chances of success and the establishment of global collaboration.

SK bioscience has announced on the 10th that positive immunogenic response and safety data were shown from the stage 1 portion of a Phase I/II study of GBP510, a vaccine candidate co-developed with the Institute for Protein Design (IPD) at the University of Washington and adjuvanted with GlaxoSmithKline’s (GSK) pandemic adjuvant system.

According to SK bioscience, 80 healthy adults participated in the stage 1 portion of Phase I/II, conducted across institutions including Korea University Guro Hospital. The generation of the neutralizing antibodies against the COVID-19 virus has been confirmed in all participants receiving the adjuvanted vaccine, demonstrating a 100% seroconversion rate.

Furthermore, the observed neutralizing antibody titer was 5 to maximum 8 times higher compared to human sera from recovered COVID-19 patients. The result has been acquired by standardized analysis using international standard material and analytic method established by the World Health Organization (WHO) and the UK’s National Institute for Biological Standards and Control (NIBSC). The convalescent sera control is inclusive of the lowest to the highest levels of neutralizing antibody formation rates.

In terms of safety, no serious adverse events following immunization (AEFIs) were detected in relation to GBP510 injection, demonstrating sufficient tolerability. SK bioscience has also completed second dosing for 247 stage 2 participants including the elderly and continues a follow-up study, demonstrating no notable safety issues so far.

Based on the positive interim data from Phase I/II clinical trial, SK bioscience has received an approval from South Korea’s Ministry of Food and Drug Safety (MFDS) for its Phase III investigational new drug (IND) application. This is the first ever MFDS Phase III IND approval for a domestically developed COVID-19 vaccine and SK bioscience is initiating the final stage of the clinical study with the goal of making it available in the first half of 2022.

■ Phase III Clinical Trials for GBP510 Through Transnational and Global Cooperation

GBP510, a next generation COVID-19 vaccine candidate designated as the first Wave 2 vaccine by Coalition for Epidemic Preparedness Innovations (CEPI), will enter the Phase III clinical trial stage with the support of unprecedented global initiatives. The cross-border cooperation around GBP510, underway across financial, technological, and procedural dimensions, has elevated positive expectations towards the development of a vaccine that is expected to further contribute to overcoming the pandemic.

Development costs of GBP510 are being supported by the Bill & Melinda Gates Foundation and CEPI. The two organizations have been behind GBP510 since the initial development stage and have committed as much as 213.70 million USD (approx. 245 billion KRW), among which about 173 million USD will be utilized for Phase III trial and other program activities. SK bioscience expects to utilize said funds for the Phase III clinical trial and approval process, the development of commercial processes geared for delivering hundreds of millions of doses yearly, the acquisition of relevant raw materials, and additional research and development against virus variants.

The IPD at UW, a world-class institution for antigen design, has contributed to maximizing GBP510’s immunogenic effects. Both SK bioscience’s DNA recombination technology and IPD’s self-assembly nanoparticle design technology have been applied to GBP510’s receptor binding domain (RBD) protein. It has been confirmed that this RBD nanoparticle with its stable structure induces a high level of neutralizing antibody titer and prohibit the replication of the virus.

GSK, a global pharmaceutical company, has also joined in cooperation for strengthening the efficacy of GBP510. In the Phase III trial, SK bioscience is combining GBP510 with GSK’s pandemic adjuvant system, which is designed to enhance the vaccine’s immunological profile and potential immune response versus when the vaccine is administered on its own. GSK’s pandemic adjuvant does this by a broad stimulation of the immune response to the spike protein antigen, leading to a pronounced and sustained immune reaction ? and thus protection.

The global Phase III clinical operation will be conducted by the International Vaccine Institute (IVI). IVI will operate multinational Phase III trials across regions like Europe and Southeast Asia, and SK bioscience will proceed with preparations to receive WHO Pre-qualification (PQ) certification and emergency use authorization (EUA) by individual countries. SK bioscience expects IVI’s network, formed through IVI’s preexisting international engagement with various global companies for COVID-19 vaccine development, to further accelerate the progress of the clinical trial and approval.

In South Korea, 14 clinical institutions including Korea University Guro Hospital are set to conduct Phase III clinical trials for GBP510. SK bioscience and the 14 clinical institutions will take a comparative clinical approach to evaluate the immunogenicity and safety of GBP510. South Korean public health authorities, including the Ministry of Health and Welfare (MOHW) and MFDS, will support administrative and institutional processes to expedite the domestic portion of Phase III trial and to secure globally acceptable study data.

SK bioscience, the Korea Disease Control and Prevention Agency (KDCA), and IVI have also recently signed a Joint Analysis Agreement for global Phase III trial. In accordance with the agreement, the three entities will participate in the analysis of neutralizing antibodies across Phase III test subjects together to secure accurate results within a shortened timeframe.

Such transnational and global cooperation for the development of GBP510 is a step forward to the goal of developing South Korea into a global vaccine hub.

■ Securing Global Common Access to Vaccines Upon Completion of Development

GBP510 was the first COVID-19 vaccine candidate to beed as part of Wave 2, a project initiated by CEPI in 2020 to support distinguished vaccine candidates. Once marketed, hundreds of millions of GBP510 doses are planned to be supplied across the world, including developing nations, through the COVAX facility.

The recombinant protein antigen vaccine platform applied to GBP510 offers advantages in terms of storage conditions and shelf life compared to COVID-19 vaccines based on other platforms, which will help the developing world secure common access to vaccines.

GBP510 is also expected to provide relief to South Korea’s domestic vaccine supply situation, which has been reliant on imported vaccines so far. Since it will be a domestic vaccine developed with SK bioscience’s technology, SK bioscience will be able to plan production and supply on its own and contribute to secure vaccine sovereignty in the long-term as its platform will allow quicker response to variant versions of the virus.

Another advantage is that hundreds of millions of vaccine doses can be produced immediately at large, commercial scale and supplied from the L HOUSE in Andong. The SK bioscience vaccine production facility has 9 separate suites that enable simultaneous production of different vaccine products. The COVID-19 vaccine manufacturing facility at L HOUSE has received Good Manufacturing Practice (GMP) certification from the EU, demonstrating a global technological standard that will serve as a springboard towards entering the global market, including those of advanced countries.

SK bioscience also continues its research on COVID-19 variants. With the technology behind GBP510, clinical trials for variant antigens are scheduled to be initiated within this year. Furthermore, plans are in place to secure GBP510 as a vaccine platform upon completion of its development to respond quickly against any type of variant.