Clover Announces Positive Phase 2 Clinical Data for RSV + hMPV ± PIV3 Respiratory Combination Vaccine Candidates in Older Adults

-- Positive Phase 2 (Australia) results strengthen potential best-in-class profile of RSV+hMPV±PIV3 combination vaccines, with the potential differentiated ability to re-vaccinate individuals previously receiving approved RSV vaccines to restore and broaden protection --

-- Robust neutralizing antibody responses across RSV, hMPV and PIV3 in Phase 2 recapitulates Phase 1 results demonstrating best-in-class breadth (with no immune interference) and no drop-off in responses in the oldest participants (75+ years) --

-- Favorable safety & tolerability profile and successful 2,000L commercial-scale production further de-risk late-stage development and commercialization --

SHANGHAI, Sept. 6, 2026 /PRNewswire/ -- 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, today announced positive preliminary data from a Phase 2 clinical trial in older adults in Australia evaluating SCB-1022 (RSV + hMPV) and SCB-1033 (RSV + hMPV + PIV3) protein-based vaccine candidates based on prefusion-stabilized F (PreF)-Trimer subunit vaccine antigens utilizing Clover's validated Trimer-Tag vaccine technology platform.

"We are pleased to announce positive Phase 2 clinical data strengthening the potential first-in-class and best-in-class profile for our RSV+hMPV±PIV3 combination vaccine candidates, with the potential differentiated ability to re-vaccinate individuals previously receiving approved RSV vaccines to restore and broaden protection," said Joshua Liang, Chief Executive Officer & Board Director of Clover. "The positive Phase 2 results significantly de-risk future late-stage development. Importantly, the results also continue to validate our differentiated Trimer-Tag platform for the development of multi-valent protein-based respiratory vaccines that have the potential to make an impact on public health and on chronic diseases caused by respiratory viruses^[1]." 

The ongoing Phase 2 trial for Clover's combination vaccine candidates is a randomized, observer-blinded, multi-center study with 420 older adults (60-85 years) enrolled in Australia, and the participants have been randomized to receive either SCB-1022 (RSV + hMPV), SCB-1033 (RSV + hMPV + PIV3) or placebo.

Immunogenicity

• Antibody titers (geometric mean titers [GMTs]) at 28 days post-vaccination in the Phase 2 were generally in-line with or trended higher than the prior Phase 1 trial.
• Geometric mean fold rises (GMFRs) in neutralizing antibodies (nAbs) at 28 days post-vaccination compared to pre-vaccination:
  • RSV nAbs: Approximately 6-9 fold increases
  • hMPV nAbs: Approximately 6-8 fold increases
  • PIV3 nAbs: Greater than 3 fold increase (approximately 5 fold increase in participants with baseline PIV3 nAbs in the bottom tertile), driven by up to approximately 20 fold increases in PIV3 PreF-specific antibodies^[2]
• No drop-off in antibody responses observed in the oldest participants (75+ years) compared to younger participants (60-74 years).
• No signs of immune interference on RSV and hMPV nAbs from the addition of PIV3 PreF antigen in SCB-1033 (RSV+hMPV+PIV3) compared to SCB-1022 (RSV+hMPV).

Respiratory Tract Infections (Based on AE Reporting)

• Approximately 62% lower rate of respiratory tract infection was observed in the vaccine groups (SCB-1022 and SCB-1033) versus the placebo group within 28 days of vaccination based on AE reporting of any respiratory tract infections (no PCR sequencing of infection cases was conducted in the study).
• Significant RSV outbreak^[3] with co-circulation^[4] of hMPV and PIV in Australia occurred during the study enrollment and follow-up period.

Safety and Reactogenicity

• SCB-1022 and SCB-1033 were generally well-tolerated; solicited local and systemic adverse events (AEs) within 7 days of vaccination were mostly mild and all transient.
  • The most common solicited AEs were fatigue, headache and injection site pain, with mean durations of approximately 2 days for the vaccine groups (SCB-1022 and SCB-1033) and the placebo group. 
• The frequency of unsolicited AEs within 28 days of vaccination was similar across the vaccine and placebo groups.
• There were no vaccine-related serious adverse events (SAEs), AEs of special interest (AESIs), or AEs leading to discontinuation.

Commercial-Scale Manufacturing Scale-Up

• In parallel with the Phase 2 trial, Clover conducted commercial-scale 2,000L bioreactor scale-up production of multiple batches of Trimer-Tagged RSV, hMPV and PIV3 PreF antigen components of SCB-1022/1033.
• The successful 2,000L production process scale-up further de-risk future late-stage development and commercialization.

Based on these positive Phase 2 results for the RSV + hMPV ± PIV3 combination vaccine candidates further validating the Trimer-Tag platform, Clover will continue to evaluate continued mid- and late-stage development plans as well as potential global collaboration opportunities for value maximization.   

About Clover 

Clover Biopharmaceuticals is a global commercial-stage biotechnology company committed to unleashing the power of innovative vaccines to save lives and improve health around the world. With integrated research and development, manufacturing and commercial capabilities as well as strong partnerships with organizations globally, Clover has a diverse pipeline of candidates that have the potential to meaningfully reduce the burden of vaccine-preventable diseases—and to make more diseases preventable.   

Clover Forward-looking Statements  

This press release contains certain forward-looking statements and information relating to us and our subsidiaries that are based on the beliefs of our management as well as assumptions made by and information currently available to our management. When used, the words "aim," "anticipate," "believe," "could," "estimate," "expect," "going forward," "intend," "may," "might," "ought to," "plan," "potential," "predict," "project," "seek," "should," "will," "would" and the negative of these words and other similar expressions, as they relate to us or our management, are intended to identify forward-looking statements.   Forward-looking statements are based on our current expectations and assumptions regarding our business, the economy and other future conditions. We give no assurance that these expectations and assumptions will prove to have been correct. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict. Our results may differ materially from those contemplated by the forward-looking statements. They are neither statements of historical fact nor guarantees or assurances of future performance. We caution you therefore against placing undue reliance on any of these forward-looking statements. Any forward-looking statement made by us in this document speaks only as of the date on which it is made. Factors or events that could cause our actual results to differ may emerge from time to time.

SOURCE Clover Biopharma