Clover Biopharmaceuticals, Ltd., a global commercial-stage biotechnology company focused on developing innovative vaccines, has announced positive preliminary results from two ongoing phase I clinical trials evaluating its combination respiratory PreF vaccine candidates—SCB-1022 (RSV+hMPV) and SCB-1033 (RSV+hMPV+PIV3)—based on the company’s Trimer-Tag platform technology.
The trials aim to address key gaps in current respiratory syncytial virus (RSV) vaccination by expanding protection to additional respiratory viruses and enabling effective re-vaccination strategies in older adults.
Promising Results from Australian Phase I Trial
In the Australian trial, 144 older adults aged 60–85 were randomized to receive one of three vaccines: SCB-1022, SCB-1033, or the RSV-only comparator SCB-1019.
Key findings include:
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RSV immune responses: Both SCB-1022 and SCB-1033 generated approximately 6–8-fold increases in RSV-A and RSV-B neutralizing antibodies (nAbs), comparable to SCB-1019.
- No immune interference: The addition of hMPV and PIV3 antigens did not diminish RSV immune responses.
- hMPV responses: Participants receiving SCB-1022 and SCB-1033 showed 6–9-fold increases in hMPV-A and hMPV-B nAbs.
- PIV3 responses: SCB-1033 induced around 4-fold increases in total PIV3 nAbs, and up to 10-fold increases in PIV3 PreF-specific antibodies.
- Safety: Both combination vaccines were generally well-tolerated, with mild local and systemic adverse events comparable to SCB-1019. No vaccine-related serious adverse events were observed.
Clover plans to advance SCB-1022 and SCB-1033 into phase II clinical trials in the first half of 2026.
U.S. Re-Vaccination Study Shows Stronger Response Than GSK’s Arexvy
A separate U.S.-based phase I study is evaluating re-vaccination potential in older adults who previously received GSK’s Arexvy RSV vaccine at least two seasons earlier. Participants were randomized to receive SCB-1019, Arexvy, or placebo.
Interim results from 34 participants show:
- SCB-1019 induced 1.6–1.8× higher geometric mean fold rises (GMFRs) in RSV-A and RSV-B nAbs compared with Arexvy.
- 69–75% of participants receiving SCB-1019 achieved ≥2-fold increases in nAbs, compared with 33–40% for Arexvy.
- Baseline antibody levels and demographic characteristics were balanced between groups.
These results suggest SCB-1019 may restore and enhance waning RSV protection, offering potential advantages over existing re-vaccination strategies. Additional data from this trial are expected in the first half of 2026.
Addressing Unmet Needs in Respiratory Disease Prevention
Clover’s combination vaccine approach targets RSV, human metapneumovirus (hMPV), and parainfluenza virus type 3 (PIV3)—three major viral causes of respiratory illness in older adults. Currently approved RSV vaccines are not designed to prevent infections caused by hMPV or PIV3 and lack robust re-vaccination solutions as immunity wanes.
“While currently approved RSV vaccines are safe and effective, significant unmet needs remain,” said Joshua Liang, CEO of Clover Biopharmaceuticals. “Our combination vaccine candidates have the potential to broaden protection and restore waning immunity in older adults.”
Expanding the Trimer-Tag Platform
The company’s Trimer-Tag technology underpins its vaccine candidates, allowing precise stabilization of viral fusion proteins in their prefusion form to elicit strong and targeted immune responses.
The new data reinforce Clover’s plans to build a first-in-class and best-in-class respiratory vaccine franchise. The company expects to progress its combination vaccine candidates into phase II trials by mid-2026
