Harvard Medical School researchers have quantified the potential human cost of National Institutes of Health (NIH) grant cancellations in 2025: the termination of 383 clinical trials in which more than 74,000 patients may have been receiving an active treatment.

Their research, published in JAMA Internal Medicine, appears to be the first to determine how many trial enrollees have been affected, said lead author Vishal Patel, MD, MPH, physician at Brigham and Women’s Hospital, Boston.

Many studies and databases have tracked the status of NIH grants this year, as the Trump administration has sought to end research it says does not align with its priorities. Even the Department of Health and Human Services (HHS) published an ongoing list of federal funding terminations.

But evaluating the impact on patients proved elusive.

“We weren’t able to easily find that information,” Patel told Medscape Medical News. “We felt like people should know,” he said.

“Unanticipated funding disruptions raise concerns about avoidable waste, data quality, and compromised ethical obligations to participants,” Patel and colleagues wrote.

Of 11,008 trials funded by NIH between February and August 15, nearly 400 lost funding during that period. For trials classified as “active and not recruiting” at the time of grant termination, 74,311 individuals were enrolled in studies in which they may have been in the process of receiving interventions, Patel and colleagues found.

They reported that studies conducted in the Northeast or outside the US, that employed behavioral health interventions, that were aimed at prevention or were in health services research, and that were in phase 1 or 1/2 were more likely to be terminated. Some 14% of grants for infectious diseases were terminated (97 of 675 funded during the period). Around 6% of grants for respiratory diseases and 5% of those for cardiovascular diseases were cancelled.

About 4% (79) of funded grants involving children younger than 18 years were terminated.

“We strongly reject the intentionally misleading portrayal of our grant management process in the JAMA Internal Medicine letter,” said Andrew Nixon, communications director at the HHS, which oversees NIH. “NIH’s portfolio improves and saves millions of lives every year through disciplined, transparent, peer-reviewed science. Selective focus on a handful of appropriately paused studies does not change that fact, and it should not be used to cast doubt on the overwhelming majority of trials that meet or exceed the gold standard of clinical research.” 

Decades-Old Trial Networks Defunded

Among those is the Adolescent Medicine Trials Network for HIV Interventions, a collaborative established in 2001 that conducts behavioral, therapeutic, microbicide, and vaccine trials in people aged 12-24 years. Its trials were forced to halt when $17 million in grants was terminated, said Sybil Hosek, PhD, one of the network’s co-principal investigators and director of the Center for Dissemination and Implementation Science at the University of Illinois College of Medicine in Chicago.

One trial was examining whether counseling can help prevent depression and decrease transmission of HIV in young people who use stimulants. Participants had to be taken off the trial. The study just restarted this month, Hosek said.

The network was also due to start a study that would have tested whether DoxyPEP (an antibiotic proven to prevent sexually transmitted infections in men) could do the same for young women. Hosek hopes that can restart.

“The harms to the communities we serve — being cut off from trials, from relationships with research teams and institutions — and the increased mistrust in research that abrupt terminations caused is the most palpable damage, and the hardest piece to rebuild,” Hosek said.

Hosek and co-leader Lisa Hightow-Weidman, MD, MPH, wrote about the termination in a new paper in the Journal of Adolescent Health. They noted that it came at a time when NIH had called for accelerating progress toward ending HIV.

The Pediatric Brain Tumor Consortium (PBTC), formed by the National Cancer Institute (NCI) in 1999, also saw its funding eliminated.

PBTC chair Ira Dunkel, MD, told Medscape Medical News that the group was due for a 5-year renewal of NIH funding in 2026. When he met with NCI officials in August, he was told that the PBTC would not be invited to apply for funding.

No reason was given. The official HHS account on X posted that it was “streamlining” the consortium’s work and “expanding support” to the Children’s Oncology Group (COG), which would result in “more capacity, faster trials, and stronger research.”

“I hope that’s true,” said Dunkel, a pediatric hematologist/oncologist at Memorial Sloan Kettering Cancer Center, New York City, who said he spoke solely on his own behalf. The PBTC has been meeting with the leadership of COG’s Pediatric Early Phase-Clinical Trial Network to forge new collaborations, he said.

Trials Come to a ‘Grinding Halt’

But, meanwhile, “everything came to a grinding halt,” said Dunkel. 

That included eight studies that were open and still enrolling, including a phase 1 trial of autologous HER2-specific CAR T cells in children with ependymoma, a cancer that often does not respond to chemotherapy.

Two due to start — one a neurosurgical intervention and one testing a vaccine as treatment for diffuse midline glioma, a very lethal cancer — may never get off the ground. Patients already in the eight trials underway were allowed to continue treatment, and PBTC is still collecting data.

But the consortium “very quickly closed all the trials to new patient(s),” said Dunkel, noting that it was concerned it would not have enough staff to meet the demands of a study.

The PBTC has funding through March 31, 2026, but it’s unclear what happens after that.

Patients who were in trials were allowed to continue treatment, and PBTC is still collecting data. One of the studies that is now closed is a phase 1 trial of autologous HER2-specific CAR T cells in children with ependymoma, a brain or spinal tumor that often does not respond to chemotherapy.

Brain cancer is the second most common type of cancer in children. Certain types still don’t have good treatments, and it’s one of the major causes of death in children, said Dunkel.

“I don’t think anybody would argue that pediatric brain tumors are not an important unmet need,” he said.

Patel, Dunkel, and Hosek reported having no relevant disclosures.

Alicia Ault is a St. Petersburg, Florida-based freelance journalist whose work has appeared in many health and science publications, including Smithsonian.com. You can find her on X at @aliciaault and on Bluesky at @aliciaault.bsky.social.