What type of study is this?

This is a Pre-Registered Trial study.

What question did this study set out to answer?

This substudy investigates T-cell responses to mRNA-1345 in adult solid organ transplant recipients.

January 14, 2026Open Forum Infectious Diseases0 citationsOpen Access

P-1447. T-Cell Responses Following Two Doses of mRNA-1345 in Adult Solid Organ Transplant Recipients

EMErick F. MayerModerna Therapeutics (United States)CWCameron R WolfeDuke University AFAnn R. FalseyUniversity of Rochester

Key Points

This substudy investigates T-cell responses to mRNA-1345 in adult solid organ transplant recipients.
Participants included adults ≥18 years with kidney, liver, or lung transplants.
Two doses of mRNA-1345 50 µg were administered 57 days apart in a phase 3 trial.
T-cell responses were assessed using peripheral blood mononuclear cells and intracellular cytokine staining.
RSV-F–specific CD4+ Th1 responses increased after both doses of mRNA-1345.
Elevated responses persisted for 6 months post-vaccination.
CD8+ T-cell responses emerged by Day 57, while Th2 responses were minimal and transient.

Abstract

Abstract Background Solid organ transplant recipients (SOTRs) are at elevated risk for severe respiratory syncytial virus (RSV) disease due to chronic immunosuppression. Cell-mediated immune responses are likely an important component of long-lasting protection against RSV. This substudy evaluates RSV-F–specific T-cell responses following 1 and 2 doses of mRNA-1345 50 µg in adult SOTRs.Figure 1.RSV PreF-Specific CD4+ Th1 Responses (IFNγ+) Through 6 Months After Vaccination With mRNA-1345 (50 µg) on Day 1 and Day 57 in Adult SOTRs Methods Adults ≥18 years with a kidney, liver, or lung transplant received 2 doses of mRNA-1345 50 µg administered 57 days apart in an ongoing, phase 3 trial (NCT06067230). Peripheral blood mononuclear cells were optionally collected from a subset of participants at baseline (Day 1, pre-dose 1), Day 15, Day 57 (pre-dose 2), Day 71, and Day 181. RSV-F (prefusion conformation) T-cell responses were assessed; CD4+ and CD8+ cells were evaluated with intracellular cytokine staining for Th1 (IFN, TNF, IL2) or Th2 (IL4, IL5, IL13) responses, in addition to other functional markers (ie, CD40L, a marker of B cell co-stimulation). Results Among 42 SOTRs (24 kidney, 8 lung, 8 liver, and 2 combined liver-kidney), RSV-F–specific CD4+ Th1 responses increased following the first mRNA-1345 dose, with an additional increase observed after Dose 2. Responses remained elevated through Day 181 (Figure). Polyfunctional CD4+ Th1 cells (expressing ≥2 or ≥3 cytokines) followed a similar trajectory. CD8+ Th1 responses were observed by Day 57. CD4+ Th2 responses showed minimal increases after Dose 1 and Dose 2, with no evidence of polyfunctionality, and were trending downward by Day 181. These trends were observed consistently across transplant types. Conclusion mRNA-1345 50 µg elicited Th1-biased CD4+ T-cell responses with minimal and transient Th2 activation in adult SOTRs. CD8+ T-cell responses were also observed. T-cell responses persisted for 6 months post-vaccination. Findings demonstrate the ability of mRNA-1345 to induce cellular immunity in severely immunocompromised population, with durable responses which may be important for prevention of severe disease over time. Disclosures Erick F. Mayer, MD, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Ann R. Falsey, MD, ADMA Biologics: Advisor/Consultant|ADMA Biologics: Honoraria|AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|AstraZeneca: Honoraria|CynaVac: Grant/Research Support|GSK: Advisor/Consultant|GSK: Honoraria|Merck: Advisor/Consultant|Merck: Honoraria|Moderna, Inc.: Advisor/Consultant|Moderna, Inc.: Grant/Research Support|Moderna, Inc.: Honoraria|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant|Sanofi Pasteur: Honoraria Christina Grassi, MD, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Avi Collins, BScN, Moderna, Inc.: Former Moderna, Inc. Employee|Moderna, Inc.: Stocks/Bonds (Public Company) Md Hasan, PhD, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds (Public Company) Hsiaohsuan Kuo, PhD, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds (Public Company) Shannon McGrath, MS, Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds (Public Company) Archana Kapoor, PhD, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Xiaolin Chang, PhD, Moderna, Inc.: Moderna, Inc. employee|Moderna, Inc.: Stocks/Bonds (Public Company) Xing Chen, Sc.D., Moderna, Inc.: Moderna, Inc. employee|Moderna, Inc.: Stocks/Bonds (Public Company) Lan Lan, PhD, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Sonia K. Stoszek, PhD, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Eleanor Wilson, MD, MHS, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Jaya Gowami, MD, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Public Company) Rituparna Das, M.D., Moderna, Inc.: Employee|Moderna, Inc.: Stocks/Bonds (Public Company) Frances Priddy, MD, MPH, Moderna, Inc.: Employee of Moderna, Inc.|Moderna, Inc.: Stocks/Bonds (Private Company)

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