Letermovir prophylaxis,
does it really help with Prevention of clinically significant CMV infection through week 24 after allogeneic HSCT?
research showsGrade C. Week-24 failure was 122/325 (37.5%) versus 103/170 (60.6%), adjusted difference -23.5 points (95% CI -32.5 to -14.6). Documented clinically significant CMV infection was 57/325 (17.5%) versus 71/170 (41.8%).
ads claimKorean HIRA coverage includes Prevymis tablets and injection under criteria for CMV-seropositive adult allogeneic-HSCT recipients, extending to day 200 for high-risk patients under the June 2025 rule.
Useful facts when choosing a product
- Merck funded the trial and several authors were Merck employees.
- The efficacy population was 495 of 565 treated patients with undetectable baseline CMV DNA.
Chamgap Semantic Classification Code
Candidate index · review held
UNK.letermovir-prophylaxis.UNK.clinically-significant-cmv-infection-through-week-24-after-allogeneic-hsct.prevent.placeboUnknown > Letermovir prophylaxis > Unknown > clinically significant CMV infection through week 24 after allogeneic HSCT > Occurrence-prevention claim > Placebo
An automated migration candidate, not an issued permanent code; exact claim scope remains under review. This machine-generated migration candidate helps retrieval but is not a permanent assignment. The original verdict ID and URL remain authoritative.
What the research actually shows
Axis 6 B0 evidence ① Allocation concealment: "randomization was performed centrally with the use of an interactive voice-response system." ② Blinding: "double-blind" placebo-controlled trial. ③ Analysis set and missingness: "Patients who discontinued the trial or had missing end-point data at week 24 were imputed as having a primary end-point event." Missing outcomes were 9/325 versus 5/170; discontinuations 56/325 versus 27/170. ④ Prespecified primary endpoint: clinically significant CMV infection through week 24 - consistent with NCT02137772
Four gates: ① Defect: none. ② Listed item: none. ③ Evidence: central allocation, double blinding, failure imputation, registered endpoint. ④ Avoidability: no confirmed avoidable defect.
Why this is classified as C (54)
A large positive effect with strong design is limited by a treatment-decision endpoint and one manufacturer trial, giving C 54.
Counterpoint. End-organ disease and initiation of preemptive therapy should be separated.
Rejudgment record. Source verified — Single manufacturer confirmatory trial using a composite that includes a treatment decision
| Endpoint | P | Symptom or function itself is the target - including patient reports and performance tests |
| Replication | R1 | Single confirmatory trial |
| Independence | I0 | Evidence comes only from manufacturer studies |
| Effect size | E+ | Meets the clinically important threshold |
Stored derived and displayed grades match; this is not a current recalculation or validity check (C).
Sub-claim grades by effect
This ingredient is marketed for several effects. A single overall grade blends strong and weak claims together, so each effect is graded separately here. The overall grade reflects the strongest disconfirming or core claim.
| Effect (sub-claim) | Grade | Basis |
|---|---|---|
| Reduced clinically significant CMV infection composite through week 24 | C | The absolute difference was -23.5 points. |
Cross-check — AI research and Codex final gate
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Marty FM et al. 2017 letermovir phase 3 | Multicenter double-blind placebo-controlled phase 3 randomized trial | 565 treated; efficacy population 495 with undetectable baseline CMV DNA (325/170) | Funded by Merck with company authors | CMV disease or viremia leading to preemptive therapy through week 24, with discontinuation/missingness imputed as failure | 122/325 (37.5%) versus 103/170 (60.6%), adjusted difference -23.5 points (95% CI -32.5 to -14.6); documented infection 57/325 versus 71/170 | Pivotal manufacturer confirmatory trial |
Receipt — 1 References
All 1 cited sources were verified for existence at the original page (as of 2026-08-26).
Final verification and publication gate: Codex · Evidence date: 2026-08-26 · Corrections: none
Cite this verdict
[Chamgap] Benefit of Letermovir for Preventing Clinically Significant Cytomegalovirus Infection after Allogeneic Stem-Cell Transplantation — Evidence Grade C·54. 1 cited sources checked. Source: https://chamgap.com/en/verdicts/immunity/letermovir-prevention-clinically-significant-cmv-allogeneic-hsct/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
What this document does and does not do
Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.