Approximately 1 in 30 clinical trials funded by the National Institutes of Health (NIH) were disrupted by grant terminations earlier this year, affecting more than 74,000 trial participants across multiple disease areas, according to a research letter published in JAMA Internal Medicine.
The analysis examined 11,008 NIH-funded interventional clinical trials that were active between February 28 and August 15, 2025, finding that 383 trials (3.5%) subsequently lost grant funding. The disruptions stemmed from the termination of 694 NIH grants across 24 of the 26 institutes and centers, representing a cumulative value of $1.81 billion in terminated awards.
Widespread Impact Across Trial Phases and Disease Areas
At the time of termination, the affected trials were at various stages: 36.1% (140 trials) were completed, 34.5% (134 trials) were actively recruiting participants, 13.7% (53 trials) were not yet recruiting, 11.1% (43 trials) were active but not recruiting, and 3.4% (13 trials) were enrolling by invitation only.
The 43 trials classified as active but not recruiting had enrolled 74,311 individuals who may have still been receiving interventions when funding was terminated. These trials also had higher median anticipated enrollment compared to trials that retained funding (105 participants versus 72 participants).
Infectious disease studies bore the heaviest burden, with 14.4% of trials in this area losing funding. Respiratory disease trials followed at 5.8%, and cardiovascular disease studies at 5%. Cancer research, representing more than 4,400 of the NIH-funded trials, saw 118 studies (2.7%) lose their grants.
Geographic and Institutional Distribution
The impact varied significantly by geographic region and trial location. Trials conducted outside the United States were more likely to lose funding than US-based trials (5.8% versus 3.4%). Among US-based trials, the Northeast region experienced the highest proportion of terminations at 6.3%, while multiregional trials saw no terminations.
Columbia University experienced the highest number of grant terminations among the 210 affected recipient institutions, with 157 terminated grants. The National Institute of Mental Health and the National Institute on Minority Health and Health Disparities had the largest number of terminated grants (128 and 77, respectively).
Trial Characteristics and Funding Patterns
Grant terminations differed significantly by trial purpose and intervention type. Prevention trials were disproportionately affected, with 8.4% losing funding compared to only 2.0% of basic science trials. Behavioral intervention trials experienced the highest disruption rate at 5.0%, while genetic intervention trials remained unaffected.
By trial phase, disruptions ranged from 3.7% of phase 1 and phase 1/2 trials to 0% for phase 2/3 studies. The National Institute of Allergy and Infectious Diseases and the National Institute on Minority Health and Health Disparities accounted for the most terminated funding, losing $505,968,126 and $223,566,041, respectively.
Implications for Research Integrity and Participant Safety
The researchers emphasized the critical nature of sustained funding for clinical trial operations and participant safety. "Because trials require sustained financial support to ensure operations and participant safety, unanticipated funding disruptions raise concerns about avoidable waste, data quality, and compromised ethical obligations to participants," the authors wrote.
Of the $1.81 billion in terminated awards, 30% ($544,024,077) had not yet been expended at the time of termination. The researchers noted that clinical trials serve as "the principal mechanism for evaluating medical interventions" and are resource-intensive endeavors often dependent on external funding.
The study authors acknowledged limitations including the lack of data on specific reasons for termination and reliance on investigator-reported trial information. However, they stressed the importance of ongoing surveillance, stating that "monitoring the trajectory of clinical trials associated with terminated NIH grants is critical for determining how these disruptions will ultimately affect future trials, reliance on nonexperimental study designs, data integrity, and health care research."
