Trimer-Tag™ Subunit Vaccines
SCB-2019 (CpG 1018/Alum), our COVID-19 vaccine candidate is anticipated to be one of the first commercialized protein-based COVID-19 vaccines globally through the COVAX Facility. It consists of two key components, an antigen and an adjuvant. Employing the Trimer-Tag™ technology platform, we have developed a SCB-2019 antigen, a stabilized trimeric form of the S-protein (S-Trimer) based on the original strain of SARS-CoV-2 virus. We created our COVID-19 vaccine candidate by combining SCB-2019 with Dynavax’s CpG 1018 advanced adjuvant and aluminum hydroxide (alum).
We are currently advancing SPECTRA, a global pivotal Phase 2/3 clinical trial evaluating the efficacy, safety, and immunogenicity of SCB-2019 (CpG 1018/Alum), and expect interim data for vaccine efficacy around the middle of 2021.
Second-generation COVID-19 vaccine candidates. Multiple variants of the SARS-CoV-2 virus have emerged and are circulating globally, including but not limited to the South Africa Variant, the U.K. Variant, and the Brazil/Japan Variant. We are actively advancing our research and development for our second-generation COVID-19 vaccine candidates. In early 2021, we initiated the production of vaccine antigens against the three aforementioned variants of concern. We expect to make a candidate selection in the first half of 2021 and initiate clinical trials thereafter.
Rabies vaccine candidate. Our rabies vaccine candidate (RABV G-Trimer) is currently in early-stage development. There is a high unmet need for rabies vaccines in developing countries, where animal immunization programs have been unsuccessful.
RSV vaccine candidate. Our RSV vaccine candidate (Fusion F Antigen-Trimer) induced a strong neutralizing antibody response in a rat immunization model. This candidate demonstrated high binding affinity (sub-picomolar) to palivizumab. Currently, there are no approved vaccines for RSV, therefore our RSV vaccine candidate could potentially address the significant unmet need worldwide if approved.
Influenza vaccine candidate.Our influenza accine candidate (Hemagglutinin (HA)-Trimer) demonstrated proof-of-concept immunogenicity and viral-challenge results in vivo in mice (pandemic and seasonal). This product could be significantly differentiated compared to existing vaccines that are comprised of toxic chemicals. We believe our influenza vaccine candidate could potentially be used in a pandemic situation or as a universal (HA-stem) flu vaccine.
HIV/AIDS vaccine candidate.Our HIV/AIDS vaccine candidate (gp120-Trimer) demonstrated strong binding affinity to broadly-neutralizing antibodies (bNAbs), suggesting preservation of important antigenic epitopes. Based on our current progress made in HIV/AIDS vaccine research, we believe our HIV/AIDS vaccine candidate is safe and effective and could hold promise for an effective prophylactic vaccine for the disease.
With the Trimer-Tag™ technology platform, we have successfully designed and developed SCB-313 as a covalently-linked, native-like trimeric fusion protein which is structurally and functionally differentiated from the dimeric antibody-based structures and other native ligand-based candidates targeting this pathway. We are developing SCB-313 for the treatment of malignant ascites (MA), malignant pleural effusions (MPE), and peritoneal carcinomatosis (PC) to address global unmet medical need of intracavitary malignancies. The indications that we are targeting for SCB-313 are diseases commonly observed in late-stage cancer patients.
We are conducting five Phase 1 clinical trials for SCB-313 in China and Australia for the treatment of intracavitary malignancies. We expect to further advance development of SCB-313 for the treatment of MA to Phase 1/2 clinical trial(s) in the second half of 2021. In addition, we plan to initiate additional Phase 1 clinical trials for SCB-313 to explore new indications, such as bladder cancer, and combination approaches in 2021.
4-1BB Agonist Candidate. We are conducting discovery programs evaluating trimeric fusion protein candidates targeting the 4-1BB pathway. It is an attractive candidate for applications in cancer immunotherapy and demonstrated potent cytotoxic immune cell activation and antitumor responses in multiple pre-clinical studies. We believe we will be able to design a native-like trimeric fusion protein to target the 4-1BB pathway. We expect to make a candidate selection and enter IND-enabling studies in the first half of 2021.
We are developing SCB-808 as a biosimilar to Enbrel (etanercept). Enbrel is a blockbuster TNF-inhibitor marketed by Amgen, Pfizer, and Takeda Pharmaceuticals with global sales of US$6.3 billion in 2020. In China, Enbrel was approved by the NMPA in February 2010 for the indications of rheumatoid arthritis (RA) and ankylosing spondylitis (AS). SCB-808 is expected to primarily compete with the reference drug Enbrel and other etanercept biosimilars that have been launched or currently under late-stage development in China. Based on the Phase 1 clinical trial results, we believe SCB-808 is the potential first-to-market, ready-for-injection, pre-filled syringe formulation of an Etanercept biosimilar in China.
We initiated a Phase 3 clinical trial in December 2019 to evaluate SCB-808’s efficacy, safety, and pharmacokinetics for the treatment of AS as compared with Enbrel which is expected to be completed in 2022.
SCB-420 is an aflibercept biosimilar currently in pre-clinical development for ophthalmologic diseases such as wAMD. Clinical trials are expected to initiate in 2021. We are also exploring SCB-219 as a novel TPOR agonist, currently in pre-clinical development for the treatment of CIT and ITP. Clinical trials are expected to initiate in 2021.