SK Bioscience said it has begun conducting clinical studies on two Covid-19 vaccine candidates.

The company is taking a dual-track strategy, focusing on contract manufacturing of a global pharmaceutical firm’s vaccine and the other developing its vaccine with its platform technology.

Especially after SK Bioscience teamed up with GSK, a global leader in vaccines, industry officials’ anticipation for a locally developed Covid-19 vaccine grew even more.

On Thursday, SK Bioscience announced that it has started a domestic phase-1/2 trial of the combination therapy, using its Covid-19 vaccine candidate GBP510 with GSK’s immunologic adjuvant AS03 (ingredient: aluminum hydroxide).

The study will evaluate the safety, tolerability, and immunogenicity of GBP510, a recombinant protein vaccine against Covid-19, in combination with the GSK’s adjuvant, in healthy adults and the elderly. According to the company’s plan submitted to the Ministry of Food and Drug safety, the trial is expected to end in April 2022.

The company recruited 260 subjects for the trial – 60 people aged between 19 and 55 for the phase-1 and 200 aged between 19 and 85 for the phase-2 study. It will conduct the trial at Inha University Hospital, Ajou University Hospital, Korea University Ansan Hospital, and Korea University Guro Hospital.

An immunologic adjuvant enhances a vaccine's effectiveness by promoting the movement of vaccine antigens in the body and extending the antigen stimulation time. The adjuvant technology allows of producing more vaccines because it reduces the number of antigens required per dose.

SK Bioscience said its Covid-19 vaccine candidate GBP510 showed more neutralizing antibodies and increased T cell activity when used with GSK’s adjuvant in an animal test.

The company’s phase-1/2 trial will receive full funding from the Bill & Melinda Gates Foundation (BMGF) and the Coalition for Epidemic Preparedness Innovations (CEPI).

SK Bioscience received a grant from BMGF in May last year and developed GBP510 jointly with the University of Washington’s Institute of Protein Design (IPD). In December, CEPI selected GBP510 as the first candidate for CEPI’s “Wave2” vaccine project, aiming to support candidates for the next-generation Covid-19 vaccines.

If GBP510 development is completed under the Wave 2 project, the company will supply the vaccine worldwide through the global vaccine-sharing scheme COVAX, led by international bodies such as CEPI, the global vaccine alliance GAVI, and the WHO.

Separately, SK Bioscience received the regulatory nod on Jan. 26 to conduct a phase-1/2 study of GBP510 with or without GSK’s AS03. The study will recruit 320 patients.

SK Bioscience is also working on another Covid-19 vaccine candidate, NBP2001.

After winning the green light for the phase-1 study plan in November, the company has completed trial participants' enrollment.

The phase-1 trial will assess NBP2001’s safety, tolerability, and immunogenicity in 50 healthy adults aged between 19 and 55 at Seoul National University Hospital and SNU Bundang Hospital.

While SK Bioscience developed GBP510 with IPD with the financial backup from international civilian organizations such as BMGF and CEPI, it worked on NBP2001 with the support of the Korea Disease Control and Prevention Agency (KCDA)’s as part of the project for synthetic antigen-based Covid-19 subunit vaccine candidates.

Although SK Bioscience is developing two Covid-19 vaccine candidates simultaneously, the company will choose only one to push for commercialization.

“It is good enough to have the single best vaccine. We will make just one kind of vaccine in the end,” an official at SK Bioscience said. “We will have to see the results, but it is unlikely that we will immediately exclude one of the two candidates after seeing the results of the phase-1 study of NBP2001 and the phase-1/2 trial of GBP510.”

At a National Assembly debate on how to develop Korean made Covid-19 vaccines on Tuesday, SK Bioscience Strategy and Planning Director Lee Sang-mok said that the company would check the interim results of the trials of the two vaccine candidates in the third quarter this year.