First Participants Dosed in Adjuvanted S-Trimer COVID-19 Vaccine Candidate Trial

Clover Biopharmaceuticals and Dynavax Technologies announced the first participants have been dosed in Clover's SPECTRA trial (Study Evaluating Protective-Efficacy and Safety of Clover's Trimeric Recombinant Protein-based and Adjuvanted COVID-19 Vaccine), a global Phase 2/3 clinical trial evaluating the efficacy, safety and immunogenicity of Clover's protein-based S-Trimer COVID-19 vaccine candidate adjuvanted with Dynavax's CpG 1018 plus alum.

The global Phase 2/3 trial is a double-blind, randomized, controlled study of the adjuvanted S-Trimer COVID-19 vaccine candidate in a two-dose regimen, given 21 days apart. The study is expected to enroll over 22,000 adult and elderly participants at multiple sites across Latin America, Asia, Europe and Africa. An independent external Data Safety Monitoring Board (DSMB) will provide safety oversight throughout the program by regular review of available efficacy and safety data. An interim analysis of the primary endpoint is expected in the middle of 2021, depending on trial enrollment and occurrence of COVID-19 cases in the study.

"Dosing the first participants in SPECTRA marks another significant milestone in our journey to develop a COVID-19 vaccine. There is still a significant need in many global communities for COVID-19 vaccines and should the Phase 2/3 interim analysis be favorable, we will work closely with regulatory authorities worldwide to make our S-Trimer COVID-19 vaccine candidate available as soon as possible," Joshua Liang, Chief Executive Officer of Clover Biopharmaceuticals, said.

"We are excited to see the first participants dosed in SPECTRA, providing an opportunity for Clover's protein subunit vaccine candidate adjuvanted with CpG 1018 to demonstrate safety and efficacy. Clover's adjuvanted vaccine candidate has the potential to be an important additional solution to address worldwide demand since it can be manufactured at large scale and stored at standard refrigeration temperature. We are proud to be collaborating with Clover on the development of this vaccine for COVID-19 and committed to supporting Clover in making the vaccine available globally," Ryan Spencer, Chief Executive Officer of Dynavax, said.

SPECTRA is fully funded by the Coalition for Epidemic Preparedness Innovations (CEPI). Through this collaboration, hundreds of millions of adjuvanted S-Trimer vaccine doses will potentially be made available for procurement and allocation through the COVAX Facility to protect the most at-risk populations in participating countries.

In December 2020, Clover reported positive clinical data from its Phase 1 trial demonstrating that its protein-based COVID-19 S-Trimer vaccine candidate in combination with Dynavax's CpG 1018 induces strong immune response, including neutralizing antibodies and cell-mediated immunity, as well as favorable safety and tolerability profiles in the adult and elderly participants. The vaccine candidate is expected to be stable long term under standard refrigeration conditions and has demonstrated stability at room temperature for at least two months, making it suitable for global distribution.

Utilizing Clover's proprietary Trimer-Tag© technology, S-Trimer is a trimeric SARS-CoV-2 spike (S)-protein subunit vaccine candidate. Similar to other enveloped RNA viruses such as HIV, RSV and Influenza, SARS-CoV-2 is also an RNA virus that has a trimeric spike (S) protein on its viral envelope. The trimeric S protein of SARS-CoV-2 is responsible for binding to host cell surface receptor ACE2 and subsequent viral entry, making it the primary target antigen for vaccine development. S-Trimer resembles the native trimeric viral spike protein and is produced via a rapid mammalian cell-culture based expression system. S-Trimer is intended to be adjuvanted.

Trimer-Tag© is an innovative drug development platform which allows the production of novel, covalently-trimerized fusion proteins. Many major disease targets are trimerization-dependent such as the tumor necrosis factor (TNF) superfamily (involved in extrinsic apoptosis, immune co-stimulation and inflammation) as well as enveloped RNA virus antigens responsible for entry into host cells. Clover is using its Trimer-Tag© technology with global IP position to develop recombinant trimerized fusion proteins that are able to effectively target these previously undruggable pathways.