Investigational RSV Vaccine Yields Positive Preliminary Data in Head-to-Head Comparison with Arexvy

Clover Biopharmaceuticals announced positive preliminary immunogenicity and safety data from its phase 1 trial evaluating the company’s RSV vaccine candidate, SCB-1019, head-to-head against GSK’s AS01E-adjuvanted RSV vaccine (Arexvy).

The ongoing phase 1 study includes 70 older adults and elderly participants who received either SCB-1019—a non-adjuvanted bivalent RSV prefusion-stabilized F-Trimer subunit vaccine candidate based on Clover's Trimer-Tag vaccine technology platform—Arexvy, or saline placebo.

Preliminary immunogenicity results included the following:

• SCB-1019 induced geometric mean titers (GMTs) in RSV-A and RSV-B neutralizing antibodies (nAbs) that were comparable to Arexvy at day 28, with no statistically significant differences observed.
  • RSV-A nAbs: SCB-1019 induced GMTs in RSV-A nAbs of approximately 30 500 IU/mL compared to approximately 26 700 IU/mL for Arexvy and 3300 IU/mL for placebo at day 28.
  • RSV-B nAbs: SCB-1019 induced GMTs in RSV-B nAbs of approximately 32 000 IU/mL compared to 37 700 IU/mL for Arexvy and 2900 IU/mL for placebo at day 28.
• SCB-1019 (bivalent RSV-A/B) included an approximately 1.5-fold higher trend in antibodies against a potent RSV-B specific neutralization epitope in site V compared to Arexvy (monovalent RSV-A), based on an exploratory competitive-ELISA assay, suggesting the potential for greater and more sustained immunological breadth upon revaccination if confirmed in subsequent clinical trials.

Regarding safety and reactogenicity, results showed significantly lower rates of local adverse events (AEs) for SCB-1019 (16.7%) compared to Arexvy (76.7%), according to the press release. SCB-1019 was generally well-tolerated, and local and systemic AEs were generally mild among people who received SCB-1019 and those who received saline placebo. Researchers did not report any vaccine-related serious AEs, AEs of special interest, or AEs leading to discontinuation.

Based on these positive phase 1 findings, Clover said it plans to start clinical trials in 2025 assessing the RSV vaccine candidate in an RSV revaccination setting and as part of a respiratory combination vaccine.

"We are pleased to announce positive head-to-head clinical data for our non-adjuvanted SCB-1019 RSV vaccine candidate compared to AS01E-adjuvanted AREXVY, indicating our potential best-in-class combined efficacy & safety profile," Joshua Liang, chief executive officer, board director, Clover, said in the press release. "While currently approved protein-based RSV vaccines are safe & effective when given as an initial dose, the ability to re-vaccinate effectively when protection against RSV disease wanes and the prevention of respiratory disease caused by other viruses related to RSV both remain unaddressed & high unmet needs globally. We look forward to evaluating SCB-1019 in an RSV re-vaccination setting and as part of a respiratory combination vaccine in clinical trials in 2025."

Reference: Clover announces positive clinical data for RSV vaccine candidate SCB-1019 compared head-to-head versus GSK's AREXVY. News release. Clover Biopharmaceuticals. October 28, 2024. Accessed October 29, 2024. https://www.prnewswire.com/news-releases/clover-announces-positive-clinical-data-for-rsv-vaccine-candidate-scb-1019-compared-head-to-head-versus-gsks-arexvy-302289224.html