Nearly 1 in 30 clinical trials were interrupted by funding cuts to the National Institutes of Health, affecting more than 74,000 patients and research into cancer, infectious disease and more, according to a newly published paper.
Clinical trials are the best way for researchers to study how medical interventions affect a patient population, doctors say.
“The types of trials that are affected are among the most rigorous way that we generate scientific evidence: randomized clinical trials,” said Dr. Anupam B. Jena, a study author and professor at Harvard Medical School. “It would be one thing if studies affected by terminated grants focused on less rigorous or important forms of research, but clinical trials are important, gold-standard in terms of evidence generation, time-intensive, and costly. Those are the last types of studies we would want to stop mid-stream.”
The paper, published Monday in JAMA Internal Medicine, found that 383 clinical trials were interrupted by the funding cuts, which Jena said was “surprisingly high” to the research team. To calculate that number, the researchers looked at all clinical trials that received NIH funding between Feb. 28, 2025, the day of the first reported grant termination, and Aug. 15, 2025. There were about 11,008 clinical trials funded by NIH grants during that time period.
More than 36% of the interrupted trials have since been completed. Another 35% were recruiting patients. About 11% of the trials were active and not recruiting patients, while 14% were active but not yet recruiting. The remaining trials were enrolling patients by invitation. Trials that had their funding interrupted had more expected participants enrolled than trials that were not affected, the researchers found.
Trials that were active and not recruiting, where participants may have been receiving interventions, had a total of 74,311 patients enrolled in them, the researchers said.
The researchers looked at the trial details to learn more about what kind of research was being interrupted. Trials conducted outside the U.S. were disproportionately affected, and within the United States, the Northeast had the highest rate of interrupted trials. More than 115 trials studying cancer were interrupted, as well as 97 trials that looked at infectious diseases. Trials studying cardiovascular diseases, mental health and reproductive health were also affected.
Jena warned that the interruptions could lead to “avoidable waste” and “impact the future willingness of patients to participate in trials.”
Jena said there is no systemic data on how often clinical trials are paused for funding lapses. Termination of federal grant funding was “exceedingly rare” before 2025, he said.
“Clinical trials aren’t light switches,” said CBS News medical contributor Dr. Céline Gounder, an editor-at-large for public health at KFF Health News. “You can’t just flip them off without consequences. Cutting off funding mid-trial wastes research dollars and puts patients at risk. This is a breach of trust with every person who volunteers for research.”
The NIH said it strongly rejected the “intentionally misleading portrayal of our grant management process” in the letter and accused the researchers of having conflicts of interest, though it did not specify what those were. The NIH highlighted the “more than 42,500 active, recruiting, or planned clinical trials across every major disease area” that it currently funds and oversees, and said the paper had a “selective focus on a handful of appropriately paused studies.”
“What they fail to mention is that NIH is undergoing a strategic realignment. We are prioritizing high-impact, high-urgency science … The biomedical research enterprise is being refocused and that’s what will keep America at the forefront of global science, safety, and innovation,” the NIH said. The agency also said the terminated or interrupted studies “likely happened because this research prioritized ideological agendas over scientific rigor and meaningful outcomes for the American people.”
The NIH is the largest funder of biomedical research. More than $2 billion in federal research grants were canceled by the NIH earlier this year as part of President Trump and the Department of Government Efficiency’s efforts to downsize the federal government. Agency spending has also been slowed, and 1,300 employees have been fired. Thousands of universities and U.S. institutions rely on NIH funding for their research.
Former NIH head Dr. Francis Collins, who led the agency for 12 years across three administrations, told CBS News in April that “every dollar that NIH gave out in 2024 to a grant is estimated to have returned $2.46 just in a year.”
“When you’re talking about medical research, when you’re talking about people’s lives, when you’re talking about clinical trials for Alzheimer’s disease or cancer that may take three or four years, you can’t just go in and decide, ‘I’m going to shut those down and maybe I’ll try something else.’ Those are people’s lives at risk,” Collins told CBS News.