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Neurofibromatosis Type 1

Recent research efforts aimed at curing Neurofibromatosis Type 1.

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Neurofibromatosis Type 1

Overview

Neurofibromatosis Type 1 (NF1) is a lifelong genetic condition caused by a disease-causing change in one copy of the NF1 gene, which normally produces neurofibromin, a protein that helps restrain cell-growth signaling. It is inherited in an autosomal-dominant pattern, although about half of cases arise from a new genetic change rather than being inherited. NF1 can affect the skin, nerves, brain, bones, blood vessels, learning, and behavior; common features include café-au-lait skin spots, freckling, benign skin neurofibromas, and learning difficulties. Some people develop plexiform neurofibromas—complex tumors growing along nerves—which can cause pain, disfigurement, loss of function, and, rarely, transform into malignant peripheral nerve sheath tumors (MPNSTs). Severity is highly variable, including within families. GeneReviews: Neurofibromatosis 1 (ncbi.nlm.nih.gov)

There is no treatment that corrects the inherited NF1 change throughout the body. Current care is therefore individualized and includes lifelong clinical surveillance, eye examinations in childhood, blood-pressure monitoring, developmental and educational support, targeted imaging when symptoms warrant it, surgery when a tumor can be safely removed, and treatment of complications such as scoliosis, optic-pathway glioma, pain, or hypertension. In the United States, the MEK inhibitors selumetinib and mirdametinib are approved for symptomatic, inoperable plexiform neurofibromas; these drugs can shrink tumors and improve symptoms for many patients but do not eliminate NF1. GeneReviews: Neurofibromatosis 1 FDA: Mirdametinib approval (ncbi.nlm.nih.gov)

Scope of Recent Research (2020–present)

Research since 2020 has been especially active in three connected areas: improving tumor control with drugs that suppress overactive RAS–MAPK signaling, finding combinations for aggressive NF1-associated cancers, and developing mutation-directed approaches that might restore neurofibromin itself. The field has delivered major practical advances—particularly two approved MEK inhibitors and adult randomized evidence for selumetinib—but a body-wide genetic cure is not yet close: gene replacement, RNA repair, exon skipping, and gene-editing concepts remain preclinical or early translational research rather than human NF1 treatments. Development of an AAV vector for NF1 gene replacement Targeted NF1 exon 17 skipping (pubmed.ncbi.nlm.nih.gov)

Major Breakthroughs and Emerging Therapies

The largest clinical advance has been MEK inhibition. Loss of neurofibromin leaves RAS signaling excessively active; MEK inhibitors act downstream of that missing brake. In 2020, the phase 2 SPRINT study reported that 35 of 50 children with symptomatic, inoperable plexiform neurofibromas had a confirmed partial response to selumetinib, defined as at least 20% tumor-volume reduction, with accompanying improvements in pain, function, or quality of life in many participants. This established that a systemic drug could meaningfully reduce previously hard-to-treat plexiform neurofibromas, although it is disease control rather than a cure. Selumetinib in children with inoperable plexiform neurofibromas (pubmed.ncbi.nlm.nih.gov)

MEK inhibition has since broadened beyond pediatric care. Mirdametinib received U.S. Food and Drug Administration approval on February 11, 2025, for adults and children aged two years and older with symptomatic plexiform neurofibromas that cannot be completely removed. In its pivotal ReNeu study, independently reviewed responses occurred in 41% of adults and 52% of children. Selumetinib was then approved for adults with symptomatic, inoperable plexiform neurofibromas on November 19, 2025, following randomized evidence from the KOMET trial. FDA: Mirdametinib approval FDA: Adult selumetinib approval (fda.gov)

The most directly curative experimental strategy is restoration of neurofibromin. In 2025, investigators reported an engineered adeno-associated virus (AAV) platform that delivers a shortened, membrane-targeted neurofibromin construct containing its RAS-regulating region. The construct suppressed RAS signaling and restored Schwann-cell differentiation in an NF1 patient-derived induced pluripotent stem-cell model; the engineered AAV showed reduced liver uptake, greater tumor targeting, and anti-tumor activity in mouse xenograft models of NF1-associated tumors. This is an important proof of principle, but it is not yet a human gene-therapy trial. Development of an AAV vector for NF1 gene replacement (pubmed.ncbi.nlm.nih.gov)

RNA-directed therapies offer another route to restoring some neurofibromin without replacing the entire large NF1 gene. A 2022 study used antisense phosphorodiamidate morpholino oligonucleotides—short synthetic molecules that alter RNA splicing—to skip NF1 exon 17 in cells carrying selected exon-17 mutations. The treatment restored functional neurofibromin in human cell models, while a mouse engineered to lack exon 17 remained viable with a normal lifespan, supporting further development for a limited subset of patients. However, the approach is mutation-specific and requires delivery to the relevant tissues. Targeted NF1 exon 17 skipping (pubmed.ncbi.nlm.nih.gov)

For individual plexiform neurofibromas, complete surgical removal remains the only intervention that can potentially cure that particular tumor. Surgery is often impossible or unsafe because these tumors intertwine with nerves, blood vessels, organs, or airways, which is why drug therapies and gene-restoration research are needed. ERN GENTURIS NF1 tumour-surveillance guideline (pmc.ncbi.nlm.nih.gov)

Clinical Trials and Experimental Approaches

The phase 2b ReNeu trial of mirdametinib enrolled 114 people with symptomatic, inoperable NF1-associated plexiform neurofibromas—58 adults and 56 children—and used blinded central review of volumetric magnetic resonance imaging (MRI). It reported confirmed objective responses in 24 adults and 29 children during the 24-cycle treatment period. The sponsor, SpringWorks Therapeutics, continues long-term follow-up, while the FDA approval makes mirdametinib an available treatment rather than solely an experimental approach. ReNeu phase 2b trial ReNeu trial record (pubmed.ncbi.nlm.nih.gov)

KOMET was a global, randomized, double-blind phase 3 trial sponsored by AstraZeneca that compared selumetinib with placebo in adults with symptomatic, inoperable plexiform neurofibromas. By cycle 16, confirmed response was 20% with selumetinib versus 5% with placebo, supporting the November 2025 U.S. adult approval. Earlier and parallel work continues to examine other pathway inhibitors: in a completed phase 2 trial led by the University of Alabama at Birmingham and the Neurofibromatosis Clinical Trials Consortium, cabozantinib produced partial responses in 8 of 19 evaluable adults with plexiform neurofibromas, but dose reductions or discontinuations due to adverse effects were common. KOMET phase 3 study Cabozantinib phase 2 trial (pubmed.ncbi.nlm.nih.gov)

For MPNST, the life-threatening cancer that can arise in a small minority of people with NF1, investigators are testing combination strategies rather than relying on MEK inhibition alone. One active phase 1/2 study evaluates selumetinib plus the bromodomain inhibitor ZEN-3694, with durvalumab, an immune-checkpoint inhibitor, added in later study parts; its phase 2 component is designed for unresectable or metastatic NF1-associated MPNST. No clinical results from this combination were available at the time of this report. Selumetinib, ZEN-3694, and durvalumab trial (clinicaltrials.gov)

Methodologies and Scientific Approaches

NF1 researchers increasingly use models that preserve the disease’s biological complexity. These include genetically engineered mice, patient-derived induced pluripotent stem cells differentiated into relevant cell types, tumor-cell cultures, and patient-derived xenografts. The recent AAV gene-replacement work combined induced pluripotent stem-cell-derived Schwann cells with in vivo capsid evolution—iteratively selecting viral shells that better reach NF1 tumors while avoiding the liver—to address delivery, one of the central barriers to gene therapy. Development of an AAV vector for NF1 gene replacement (pubmed.ncbi.nlm.nih.gov)

Researchers are also improving human tumor models and outcome measurements. Patient-derived cutaneous-neurofibroma organoids retain important features of the original tumors and have been used for multi-drug screening, while clinical trials use three-dimensional volumetric MRI rather than simple diameter measurements to quantify plexiform-neurofibroma response. Some trials pair imaging with tumor biopsies and blood-based measures of pathway activity, including ERK phosphorylation, to identify why tumors respond, resist treatment, or regrow after therapy ends. Patient-derived cutaneous-neurofibroma organoids NCI adult selumetinib phase 2 trial (pubmed.ncbi.nlm.nih.gov)

Leading Institutions and Funding

The U.S. National Cancer Institute, University of Alabama at Birmingham, Children’s Hospital of Philadelphia, Johns Hopkins University, Cincinnati Children’s Hospital Medical Center, and other sites in the Neurofibromatosis Clinical Trials Consortium have been central to NF1 drug development. NCI-led work has produced important selumetinib studies, while the Johns Hopkins-led AAV project illustrates the expansion of the field toward targeted gene replacement. NCI adult selumetinib phase 2 trial Development of an AAV vector for NF1 gene replacement (clinicaltrials.gov)

Public and philanthropic funding remain essential because NF1 spans rare-disease, cancer, neurological, and developmental research. The U.S. Department of Defense Congressionally Directed Medical Research Programs’ Neurofibromatosis Research Program reports a Fiscal Year 2026 appropriation of $25 million and $452.9 million in appropriations from Fiscal Years 1996 through 2024. The Children’s Tumor Foundation announced nearly $2 million in 2025 Drug Discovery Initiative awards for new NF1, NF2-related schwannomatosis, and schwannomatosis treatment projects. Department of Defense Neurofibromatosis Research Program Children’s Tumor Foundation Drug Discovery Initiative awards (cdmrp.health.mil)

Strengths, Limitations, and Challenges

A major strength of recent NF1 research is that it has translated disease biology into effective tumor-directed medicines. MEK inhibitors can reduce plexiform-neurofibroma volume and pain in both children and adults, and the availability of two U.S.-approved options is a substantial improvement over the pre-2020 landscape. The strongest evidence is for symptomatic, inoperable plexiform neurofibromas; it does not establish that these medicines prevent every NF1 manifestation, eradicate tumor-initiating cells, or correct the inherited mutation. FDA: Mirdametinib approval FDA: Adult selumetinib approval (fda.gov)

Important limitations remain. MEK inhibitors can cause rash, diarrhea, nausea, muscle-enzyme elevations, heart dysfunction, and eye toxicity, requiring monitoring and sometimes dose modification or discontinuation. Tumor response is incomplete and variable, and the ideal treatment duration is uncertain; in a recent pediatric and young-adult trametinib study, some participants required further therapy after stopping treatment because of tumor growth or symptoms. Gene replacement faces particularly difficult delivery challenges because NF1 is large, disease-relevant cells are distributed throughout the body, and a therapy must achieve adequate long-term activity without harmful immune responses or off-target effects. FDA: Mirdametinib approval TRAM-01 phase 2 study Development of an AAV vector for NF1 gene replacement (fda.gov)

Outlook and Future Directions

As of October 25, 2026, NF1 research is closer to durable control of important complications than to a whole-body cure. Near-term milestones include determining how long MEK inhibition should continue, identifying biomarkers that predict durable response or resistance, improving therapies for MPNST, and testing whether gene-restoration platforms can safely reach Schwann cells and other relevant tissues in large-animal and then human studies. A true cure will likely require safe, durable correction or functional replacement of neurofibromin in enough disease-relevant cells to prevent tumors and other manifestations—not merely shrinking existing tumors—so the promising AAV and RNA approaches should be viewed as foundational preclinical steps rather than imminent clinical cures. Development of an AAV vector for NF1 gene replacement Targeted NF1 exon 17 skipping (pubmed.ncbi.nlm.nih.gov)

References

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