Clover Reports Positive Early Phase Ⅰ Results for Bivalent RSV Vaccine SCB-1019 in Seniors

Clover Biopharmaceuticals, Ltd. has unveiled promising preliminary data from its Phase I trial of the bivalent RSV prefusion-stabilized F (PreF)-Trimer subunit vaccine candidate, SCB-1019. The vaccine, based on Clover's Trimer-Tag platform, targets respiratory syncytial virus (RSV) and aims to address both RSV-A and RSV-B strains. The study focused on an older adult and elderly cohort (aged 60-85), marking the first RSV PreF vaccine candidate developed in China to reach the clinical trial stage and produce clinical data.

According to Clover, the Phase I trial has shown that SCB-1019 considerably boosts neutralizing antibody levels. Specifically, the vaccine increased RSV-A neutralizing antibody titers up to approximately 7,900 IU/mL, which is up to an eight-fold rise. In the case of RSV-B, antibody titers surged to roughly 46,700 IU/mL, an eleven-fold increase. These figures contrast sharply with the much lower antibody levels observed in the saline placebo group.

The trial involved 48 participants in the older adult and elderly cohort, divided into groups receiving either the SCB-1019 vaccine or a saline placebo. The results showed that SCB-1019 induced significant geometric mean titers (GMTs) for RSV-A and RSV-B neutralizing antibodies by Day 28. Importantly, no substantial increase in antibody levels was noted in the placebo group.

When the data was further scrutinized, particularly among subjects with already high baseline antibody levels likely due to recent RSV outbreaks, the geometric mean fold rise (GMFR) was especially pronounced. For subjects with the lowest quartile baseline nAb titers, the GMFRs for RSV-A and RSV-B neutralizing antibodies were up to eight-fold and eleven-fold, respectively, by Day 28 compared to pre-vaccination levels. This substantiates the vaccine's potential efficacy against both strains of RSV.

On the safety front, SCB-1019 exhibited a favorable profile. The vaccine was generally well-tolerated, with reported adverse events (AEs) mostly mild and comparable to those observed in the saline placebo group. There were no serious adverse events (SAEs), adverse events of special interest (AESIs), or any events leading to discontinuation, indicating a promising safety and reactogenicity profile. This safety data suggests that SCB-1019 might offer a better safety profile compared to some existing oil-in-water adjuvanted or mRNA-based RSV vaccines.

"The promising results in the older adult cohort demonstrate the broad and significant antibody responses elicited by SCB-1019," said Joshua Liang, Chief Executive Officer and Board Director of Clover. "We eagerly await the full Phase I data by the end of 2024, which will support the ongoing development and potentially offer a differentiated profile globally."

The Phase I trial, conducted in Australia, is a randomized, placebo-controlled study that assesses the safety, reactogenicity, and immunogenicity of SCB-1019 at various dose levels and formulations in both young and older adults. The comprehensive safety and immunogenicity results expected by year-end 2024 will be pivotal in driving further development and positioning the vaccine in global markets.

Clover Biopharmaceuticals is a global commercial-stage biotechnology firm focused on developing innovative vaccines to combat vaccine-preventable diseases. With robust research, development, and commercial capabilities, Clover is well-positioned to make significant strides in reducing the burden of such diseases worldwide. The company boasts a diverse pipeline with the potential to address numerous health challenges, aiming to make more diseases preventable through cutting-edge vaccine technology.