1. CLOVER (CLOstridium difficile Vaccine Efficacy tRial) Study: A Phase 3, Randomized Trial Investigating the Efficacy and Safety of a Detoxified Toxin A/B Vaccine in Adults 50 Years and Older at Increased Risk of Clostridioides difficile Infection.
- Author
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Donskey CJ, Dubberke ER, Klein NP, Liles EG, Szymkowiak K, Wilcox MH, Lawrence J, Bouguermouh S, Zhang H, Koury K, Bailey R, Smith HM, Lockhart S, Lamberth E, Kalina WV, Pride MW, Webber C, Anderson AS, Jansen KU, Gruber WC, and Kitchin N
- Subjects
- Humans, Male, Female, Middle Aged, Aged, Aged, 80 and over, Enterotoxins, Bacterial Proteins immunology, Clostridium Infections prevention & control, Clostridioides difficile, Bacterial Vaccines adverse effects, Bacterial Vaccines administration & dosage, Bacterial Toxins
- Abstract
Background: Clostridioides difficile infection (CDI) causes substantial mortality and healthcare burden. We assessed the detoxified toxin-A/B PF-06425090 vaccine for primary CDI prevention., Methods: This phase 3 observer-blinded study randomized (1:1) ≥50-year-olds at increased CDI risk (N = 17 535) to receive 3 PF-06425090 or placebo doses (0, 1, and 6 months). Primary end points were first CDI episode (≥3 unformed stools within 24 hours; central laboratory-confirmed toxin A/B positive) ≥14 days post-dose 3 (PD3; first primary) and post-dose 2 (PD2; second primary). CDI duration, need for CDI-related medical attention (secondary end points), and antibiotic use (post hoc analysis) PD3 were evaluated. Tolerability and safety were assessed., Results: The primary end point was not met (17 PF-06425090 and 25 placebo recipients had first CDI episode ≥14 days PD3 [vaccine efficacy (VE) = 31.0% (96.4% confidence interval [CI], -38.7% to 66.6%)]; 24 PF-06425090 and 34 placebo recipients had first CDI episode ≥14 days PD2 [VE = 28.6% (96.4% CI, -28.4% to 61.0%)]. Median CDI duration was lower with PF-06425090 (1 day) versus placebo (4 days; 2-sided nominal P = .02). Of participants with first CDI episode, 0 PF-06425090 and 11 placebo recipients sought CDI-related medical attention (post hoc analysis estimated VE = 100%; 95% CI, 59.6% to 100.0%) and 0 PF-06425090 and 10 placebo recipients required antibiotic treatment (VE = 100%; 95% CI, 54.8% to 100.0%). Local reactions were more frequent in PF-06425090 recipients, and systemic events were generally similar between groups; most were mild to moderate. Adverse event rates were similar between groups., Conclusions: Three PF-06425090 doses were safe and well tolerated. Although the primary end point was not met, PF-06425090 reduced symptom duration, CDI that required medical attention, and CDI-directed antibiotic treatment, highlighting its potential to reduce CDI-associated healthcare burden., Clinical Trials Registration: NCT03090191., Competing Interests: Potential conflicts of interest. C. J. D. receives research support from Pfizer, Clorox, and Ecolab. E. R. D. receives research support from Theriva Biologics, Ferring, and Pfizer and is a consultant for Merck, Pfizer, Seres, Ferring, AstraZeneca, Abbott, Summit, and GSK. N. P. K. receives research support from Pfizer, Merck, Sanofi Pasteur, and GSK. E. G. L. receives research support from Pfizer. K. S. reports no conflicts of interest. M. H. W. has received consulting fees from Ferring, GSK, Nestlé, Paion, Pfizer, Phico Therapeutics, Qpex Biopharma, Seres, Summit, Tillotts, and Vedanta; lecture fees from GSK, Pfizer, Seres, and Tillotts; and grant support from GSK, Pfizer, Seres, Summit, the European Tissue Symposium, and Tillotts. J. L., S. B., H. Z., K. K., R. B., H. M. S., S. L., E. L., W. V. K., M. W. P. C. W., A. S. A., K. U. J., W. C. G., and N. K. are current or former employees of Pfizer and may hold stock or stock options. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2024
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