Researchers at Cincinnati Children's have reported that a newer class of cancer drugs shrank the nerve tumors caused by neurofibromatosis type 1 at least as effectively as the MEK inhibitors currently approved for the condition, in a study conducted entirely in mice.
The findings were published on September 2, 2026, in the journal Science Advances by Nancy Ratner and nine co-authors. The full paper reports that KRAS is required for these tumors to form and that blocking it also reduced tumors that had already developed.
NF1 affects roughly one in every 2,500 to 3,000 newborns, and an estimated 100,000 to 120,000 people in the United States live with a neurofibromatosis diagnosis. For those families, the practical meaning is narrow but real. Existing MEK inhibitors work for many patients but not all, and side effects lead some children to stop treatment. A second drug target would matter for families who have run out of options within the current class.
It is also, at this stage, a mouse result. No person has received a KRAS inhibitor for NF1.
Tumors That Grow Along Nerves From Childhood
Neurofibromatosis type 1 is a genetic condition caused by changes in the NF1 gene, which normally produces a protein that keeps RAS signaling in check. When that brake fails, RAS signaling runs high, and Schwann cell tumors form within peripheral nerves. About half of cases are inherited from a parent, and the rest arise from new genetic changes.
Plexiform neurofibromas are the most consequential of these. They typically begin growing in childhood, can involve large nerve networks, and cause pain, disfigurement, loss of function, and airway or spinal compression depending on location. Roughly 8 to 13 percent of patients go on to develop malignant peripheral nerve sheath tumors, often during adolescence or young adulthood. Surgery is often impossible because the tumors thread through nerves rather than sitting beside them.
Until recently, there was no effective drug treatment. That changed with MEK inhibitors, which act further downstream in the same signaling pathway. Two are now approved for children with symptomatic inoperable plexiform neurofibromas, selumetinib in 2020 and mirdametinib in 2025, both approved in significant part because of Cincinnati Children's neurofibromatosis research. The benefits have limits: about 30 percent of patients show no response, tumor shrinkage rarely exceeds 20 percent, and keeping tumors in check requires continuous therapy with dose-limiting toxicities.
KRAS sits closer to the origin of the signal. The team tested an oral KRAS inhibitor called BI6674, given twice daily, in a mouse model closely related to the one that predicted MEK inhibitor benefit in humans.
Results Came From Mice, Not People
The study is preclinical. The animals were a genetically engineered mouse line that develops plexiform neurofibromas through the same genetic mechanism seen in people, and the same class of model that previously anticipated how MEK inhibitors would perform in patients.
The KRAS inhibitor reduced neurofibroma burden and changed how immune cells behaved inside the tumor. Examinations of nerve roots, dorsal root ganglia, and peripheral nerves in treated mice found no excess tissue growth or tumor formation, even in animals 25 to 30 months old.
Ratner described the results as "compelling preclinical evidence for KRAS inhibition as a novel treatment strategy."She noted that the translational value of the mouse system was demonstrated when these mice successfully predicted the clinical benefit of MEK inhibitors.
That track record is the strongest argument for taking the result seriously. It is not a guarantee. Drug candidates routinely perform well in animal models and fail in human trials, and NF1 tumor biology in children involves growth, development, and years of continuous treatment that a mouse study cannot replicate.
The researchers were explicit about what remains unresolved. Human clinical trials will be needed to verify any benefit. Optimal dosing schedules, particularly for growing children, have not been determined. How long any benefit would last in people compared with mice is unknown. And BI6674 may not be the best KRAS inhibitor for this purpose; the team plans to test others that have emerged in recent years.
Families Weighing Current Treatment Against Future Options
Nothing about this study changes treatment today, and that is the most important practical point for parents.
Children currently taking an approved MEK inhibitor should continue as prescribed. No one should stop, pause, or adjust a dose based on preclinical findings. KRAS inhibitors are not available for NF1 outside research settings, and no clinical trial in NF1 has been announced.
Families for whom this eventually matters most are those whose children have not responded adequately to MEK inhibitors, those who discontinued because of side effects, and those with tumors in locations where surgery is not an option. Because the two drugs act at different points in the same pathway, the researchers also raised the possibility of using them together in patients who can tolerate combined therapy, though that has not been tested in people either.
Parents who want to prepare can ask their child's neuro-oncology or NF1 clinic team whether the center participates in NF1 clinical trials and whether they should be notified when new studies open. The NF Clinical Trials Consortium runs multi-center studies, and the federal registry lists active NF1 trials by location. Being connected to a center that enrolls patients is the realistic route to early access if trials begin.
Cost and coverage questions do not arise yet, since no product exists for this use. When and if they do, MEK inhibitor experience suggests that specialty pharmacy access, prior authorization, and manufacturer patient assistance programs will be the relevant terrain.
Trials, Dosing Questions, and the Road to a Clinic
The next step the researchers named is testing additional KRAS inhibitors to identify which compound and schedule performs best in the animal model. That work precedes any human study.
A realistic sequence would move from expanded preclinical testing to a phase one trial establishing safety and dosing, then to phase two efficacy work, and only then toward regulatory review. For a pediatric population with a chronic condition requiring long-term treatment, safety requirements are demanding and timelines are measured in years rather than months.
Several KRAS inhibitors are already approved or in late-stage development for cancers driven by KRAS mutations, which means the safety profile of the class in adults is partially characterized. That could shorten early-phase work, though NF1 involves a different biological context and a younger population.
Families should watch for two specific signals: an announced phase one trial of a KRAS inhibitor in NF1, and publication of results from additional KRAS compounds in the same mouse model. Either would move this from a laboratory finding toward something a clinic could eventually offer. Neither has happened yet.
Key Questions Answered
What did the study actually find? In a mouse model of neurofibromatosis type 1, blocking KRAS prevented plexiform neurofibromas from forming and reduced tumors that had already developed, performing at least as well as MEK inhibitors. The findings were published in Science Advances on September 2, 2026.
Were any people treated in this study? No. The research was conducted entirely in mice. No human has received a KRAS inhibitor for NF1, and no clinical trial in NF1 has been announced.
Should a child currently on a MEK inhibitor change treatment? No. Approved MEK inhibitors remain the standard drug treatment for symptomatic inoperable plexiform neurofibromas. No one should stop or adjust a prescribed medication based on preclinical findings without speaking to their clinician.
What is a plexiform neurofibroma? It is a tumor that grows within peripheral nerves in people with NF1, typically beginning in childhood. These tumors can cause pain, disfigurement, and loss of function, and are often impossible to remove surgically because they thread through nerve networks.
Why might KRAS be a better target than MEK? KRAS sits closer to the start of the signaling pathway that drives these tumors, while MEK acts further downstream. Targeting a different point could help patients who do not respond to MEK inhibitors or cannot tolerate them, and the researchers suggested the two might eventually be combined.
How long before this could reach patients? There is no timeline. The researchers must first test additional KRAS inhibitors in animals, then establish safety and dosing in a phase one human trial. For a pediatric condition requiring long-term treatment, that process typically takes years.
How can a family find NF1 clinical trials? Ask the child's NF1 or neuro-oncology clinic whether the center enrolls in NF1 studies and whether the family can be notified when trials open. Active NF1 trials are also listed by location on the federal clinical trials registry.
