1048. Double-Blind, Randomized, Placebo-Controlled Phase 2b Multicenter Trial of V160, a Replication-Defective Human Cytomegalovirus (CMV) Vaccine
Bibliographic record
Abstract
Abstract Background Preventing congenital cytomegalovirus infection (CMVi) is an important unmet need. Natural maternal immunity to CMV acquired prior to pregnancy appears to reduce fetal transmission. In a Phase 1 trial, V160, a replication-defective CMV vaccine expressing the pentameric complex, induced humoral and cell-mediated immune (CMI) responses comparable to natural immunity. Methods Healthy, CMV-seronegative women aged 16–35 years were randomized 1:1:1 to receive double-blind V160 in a 3- or 2-dose regimen or placebo. Primary and secondary endpoints were efficacy in reducing the incidence of CMVi with 3-dose or 2-dose regimens of V160 vs placebo, respectively, using a fixed-event design. Monthly urine and saliva samples were collected to identify CMVi by polymerase chain reaction (PCR) with a single positive sample considered evidence of infection. Immunoglobulin G (IgG) binding to glycoprotein B (gB) and CMV-specific neutralizing antibody (NAb) were measured in all participants, and CMI responses were measured in a subset. Injection-site and systemic adverse events (AEs) were collected for 5 days and 14 days, respectively, after each vaccination and serious AEs were collected for the trial duration. Results 2200 women from 7 countries were enrolled (of 7458 screened). Over 80% of participants received all doses, and compliance with saliva and urine samples was > 95%. Vaccine efficacy (VE) of 42.4% (95% CI -13.5, 71.1%) was demonstrated in the 3-dose group vs placebo. In the 2-dose group, VE was -32.0% (95% CI -135.0, 25.0%). Both the quantity and duration of CMV shedding in urine and saliva among cases of CMVi decreased in the 3-dose, but not the 2-dose group vs placebo. Both V160 regimens elicited humoral and CMI responses detected by CMV-specific NAb, gB IgG, and ELISpot, which peaked at Month 7 and continued to be detectable at Month 24. Mild to moderate AEs were more frequently reported in V160 vs placebo recipients, but no vaccine-related serious AEs or deaths were reported. Conclusion V160 was well tolerated and immunogenic, but neither the 3-dose nor 2-dose regimen demonstrated significant efficacy against CMVi as defined in this trial. The quantity and duration of CMV shedding was reduced in the 3-dose group, suggesting V160 may improve immune control of viral replication after CMVi. Disclosures Rituparna Das, MD, Merck & Co, Inc. (Employee) Daniel Blazquez-Gamero, MD, MSD (Other Financial or Material Support, Fees for lectures in educational activities) Soren Gantt, MD, Altona Diagnostics (Research Grant or Support)Merck (Consultant, Grant/Research Support)Meridian Biosciences (Research Grant or Support)Moderna (Consultant, Research Grant or Support)VBI Vaccines Inc (Research Grant or Support) Oliver Bautista, PhD, Merck & Co, Inc. (Employee) Karen Beck, RN, BSN, Merck & Co, Inc. (Employee) Anthony Conlon, PhD, Merck & Co, Inc. (Employee) Daniel Rosenbloom, PhD, Merck & Co, Inc. (Employee) Dai Wang, PhD, Merck & Co, Inc. (Employee) Michael Ritter, BA, Merck & Co, Inc. (Employee) Beth Arnold, MS, Merck & Co, Inc. (Employee, Shareholder) Paula Annunziato, MD, Merck & Co, Inc. (Employee) Kevin Russell, MD, MTM&H, Merck & Co., Inc. (Employee, Shareholder)
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.003 | 0.003 |
| Insufficient payload (model declined to judge) | 0.016 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".