Clover Biopharmaceuticals, Ltd. (Clover; HKEX: 02197), a global commercial-stage biotechnology company committed to unleashing the power of innovative vaccines to save lives and improve health around the world,  announced positive preliminary immunogenicity and safety data in the initial young adult cohort from its Phase I trial evaluating SCB-1019 – the company's bivalent RSV prefusion-stabilized F (PreF)-Trimer subunit vaccine candidate – which is based on Clover's Trimer-Tag vaccine technology platform. 

"We are encouraged by the progress and positive preliminary Phase I results for our bivalent RSV PreF vaccine candidate utilizing our validated Trimer-Tag platform, demonstrating broad and significant neutralizing antibody responses against both RSV-A and RSV-B," said Joshua Liang, Chief Executive Officer & Board Director of Clover. "As the first RSV PreF vaccine candidate developed in China to enter the clinical trial stage and now the first to generate clinical data, we look forward to the additional Phase I clinical data in our initial target older adult population in the second half of 2024 as planned."

In the initial cohort enrolling young adults (aged 18-59) in the Phase I trial receiving either SCB-1019 or saline placebo, the preliminary results for geometric mean titers (GMTs) and geometric fold rises (GMFRs) for neutralizing antibodies on Day 0 (pre-vaccination) and Day 28 (post-vaccination) were as follows:

The RSV-A and RSV-B neutralization assays in this study were conducted at a third-party testing laboratory utilizing validated clinical assays and the NIBSC 16/284 reference standard sera, with assay values expressed as international units per milliliter (IU/mL).

Clover's preliminary immunogenicity data across both RSV-A and RSV-B neutralization appear to be in-line or potentially favorable compared to other protein subunit RSV PreF vaccines^{[1, 2, 3]} and are supportive of Clover's bivalent RSV-A/B approach, given that other monovalent RSV-A vaccines have previously observed lower immune responses and/or efficacy against RSV-B ^{[1, 4, 5]}. The results also confirm that Clover's PreF antigens in SCB-1019 are in the stabilized prefusion and trimeric form, further supported by exploratory immunogenicity results demonstrating significant increases in Site Ø neutralizing antibody-competitive titers. Additionally, SCB-1019 vaccination did not observe any notable safety or reactogenicity issues in this initial young adult cohort, enabling the planned enrollment of older adults to proceed in the Phase I clinical trial.

The Phase I clinical trial in Australia is a randomized, placebo-controlled study to assess the safety, reactogenicity and immunogenicity of SCB-1019 at multiple dose levels and in different formulations in young and older adults. Additional safety and immunogenicity results in older adults are expected by the second half of 2024.