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A transient low-dose MEKi treatment in a pre-clinical model prevents NF1-OPG formation

Using targeted signaling pathway therapy to prevent pediatric glioma formation

Researchers at Children’s National Hospital identified a vulnerability in a developmental signaling pathway that can be hijacked to drive pediatric low-grade glioma (pLGG) formation, according to a pre-clinical study published in Developmental Cell. The study demonstrated that targeted treatment prevents tumor formation, long before irreversible damage to the optic nerve can cause permanent loss of vision. This finding will inform chemo-prevention therapeutic trials in the future.

Brain tumors are the most common solid tumors in children, the most prevalent of which are pLGGs. Approximately 10% to 15% of pLGGs arise in patients with the familial cancer predisposition syndrome known as neurofibromatosis type 1 (NF1). This is a genetic condition that increases risks of developing tumors along the nerves and in the brain.

Nearly 20% of children with NF1 develop pLGGs along the optic pathway, also known as NF1-associated optic pathway glioma (NF1-OPG). Despite many advances in cancer therapy, there are no definitive therapies available that prevent or alleviate the neurological deficits (i.e. vision loss) and that could improve the quality of life.

“The evidence presented can inform chemoprevention therapeutic trials for children with NF1-OPG,” said Yuan Zhu, Ph.D., scientific director and Gilbert Family Endowed professor at the Gilbert Family Neurofibromatosis Institute and associate director of the Center for Cancer and Immunology Research, both part of Children’s National. “This therapeutic strategy may also be applicable to children with the developmental disorders that are at high risk of developing pediatric tumors, such as other RASopathies.”

The mechanism of vulnerability to pLGGs during development is not fully understood. It has been implied that the cell population of origin for this debilitating tumor is transiently proliferative during development. The NF1 gene produces a protein that helps regulate normal cell proliferation, survival and differentiation by inhibiting MEK/ERK signaling. When there is loss of function in NF1, it abnormally activates the MEK/ERK signaling pathway and leads to tumor formation.

Certain cells that exist transiently during the normal development of the brain and optic nerve are vulnerable to tumor formation because they depend on the MEK/ERK signaling. In this study, researchers in Zhu’s lab identified cells that were MEK/ERK pathway dependent and grew during a transient developmental window as the lineage-of-origin for NF1-OPG in the optic nerve. The researchers used a genetically engineered pre-clinical model to design a transient, low-dose chemo-preventative strategy, which prevented these tumors entirely.

“When we provided a dose-dependent inhibition of MEK/ERK signaling, it rescued the emergence and increase of brain lipid binding protein-expressing (BLBP+) migrating GPs glial progenitors, preventing NF1-OPG formation,” wrote Jecrois et al. “Equally importantly, the degree of ERK inhibition required for preventing NF1-OPG formation also greatly improved the health and survival of the NF1-deficient model.”

Ongoing clinical trials using MEK inhibitors (MEKi) are being performed for children as young as 1 month old. Thus, it becomes increasingly feasible to design a chemo-preventative trial using a MEKi to treat children with NF1. These treatment paradigms may have the potential to not only prevent OPG formation, but also other NF1-associated and RASopathies-associated developmental defects and tumors.

A transient low-dose MEKi treatment in a pre-clinical model prevents NF1-OPG formation

A transient low-dose MEKi treatment in a pre-clinical model prevents NF1-OPG formation. The middle panels highlighted by a red dashed box show an OPG in the optic nerve (arrows, top), exhibiting abnormal triply-labeled tumor cells, inflammation and nerve damage (the bottom three panels), which are absent in the normal (left panels) or MEKi-treated Nf1-deficient optic nerves (right panels). [Credit: Jecrois et al., Developmental Cell, (2021)]

Maddox and family

Family love and the right care for neurofibromatosis type 1 give Maddox a fresh start

Maddox and family

Maddox and his family in early 2020.

13-year-old Maddox Gibson is learning to cook. He says he wants to be a chef and wants to make meals for people who need it most — the homeless and the hungry.

It makes sense that he’s eager to help people who need it. As a young child growing up in a group home in his native country of China, he knows firsthand how important that support can be. In 2017 at age 10, he found his own endless supply of love and support when he met and was adopted by the Gibson family.

Zhen Chao, now called Maddox, was born in China with a genetic condition called neurofibromatosis type 1 that can cause painful or disfiguring tumors called plexiform neurofibromas. Zhen Chao had two on his head when he arrived — on his scalp and on his left optic nerve — which had been largely untreated for most of his life in China. On top of that, his right leg had been fractured and not fixed properly years before, causing him pain and weakness that left him wheelchair bound.

Adoptive mom Lindsey, a registered nurse, knew he would need special care to meet all the unique challenges he faced, and she’d done her homework — he needed the expertise of Miriam Bornhorst, M.D.,  and the Gilbert Family Neurofibromatosis Institute at Children’s National Hospital to help him thrive in his new life in the U.S. Since shortly after he came to the U.S., Lindsey has been driving Maddox the 6-plus hours from their home in North Carolina to Washington, D.C., regularly, to get care for all of his health challenges.

Maddox’s optic neurofibroma was too large when he arrived at Children’s National for a simple surgical removal. Due to her role as the lead investigator on a cutting edge clinical trial for the orphan drug selumetinib — a so-called MEK inhibitor that has shown early promise at reducing the cell growth of tumors like plexiform neurofibromas, Dr. Bornhorst enrolled Maddox in a compassionate use program for the drug, an opportunity that is not widely available. The drug was initially developed for something completely different — treatment of melanoma and non-small cell lung cancer in adults–but has been adapted through its FDA orphan drug designation for pediatric clinical trials in NF1. In the time since Maddox started taking it, it was approved for use in NF1 patients by the FDA.

The trial drug did its job — in late 2019, Maddox’s tumor had shrunk enough that chief neurosurgeon Robert Keating, M.D., and plastic surgeon Michael Boyajian, M.D., were able to successfully remove it. Follow-up procedures led by that team have also worked to repair the tissue that was impacted by the optic neurofibroma.

In addition to treatment of his neurofibromas, Maddox and his mom are able to see every service they need during one stay in D.C. The Neurofibromatosis Institute works closely across specialties, so his corrective surgery for his leg from Children’s chief of orthopaedics, Matthew Oetgen, M.D., MBA, in September 2019. He was assessed and prescribed physical therapy early in the process and even before surgery, so now he’s stronger than ever and walking. Learning difficulties, including autism and ADHD are common in NF1 patients, and so the NF Institute’s neuropsychology team has evaluated him and worked with the family to find resources and strategies near home that will support him. It should be noted, those learning difficulties only became apparent after Maddox taught himself English from scratch in only two years’ time with the help of his school’s ESOL program.

This kind of full spectrum care, from clinical assessment to surgical treatment and psychological supports, is crucial to the lives of patients with neurofibromatosis type 1 and is only available at a pediatric specialty care institution like Children’s National. The hospital has gathered some of the preeminent researchers, surgeons, and physicians within the NF Institute to make sure that the care families will travel hundreds of miles to receive is the best possible, using the latest evidence-based treatments for every challenge they face.

Though his care and follow-ups will continue at Children’s National Hospital and his condition may pose  new challenges in the future, for now, Maddox is able to focus on exploring new things and doing what he loves — playing outdoors with his family, learning to cook and building with Legos.

$1M grant funds research on quantitative imaging for tumors

“For children who are at risk of losing their vision, this project will bring a window of opportunity for physicians to start treatment earlier and save their vision,” says Marius George Linguraru, DPhil, MA, MSc.

A team from Children’s National Hospital is part of a project receiving a two-year grant of nearly $1,000,000 from the National Institutes of Health (NIH) for the first pediatric project in the Quantitative Imaging Network (QIN) of the National Cancer Institute (NCI). Marius George Linguraru, DPhil, MA, MSc, principal investigator from the Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National Hospital in Washington, D.C., is one of two principal investigators on the project, which focuses on developing quantitative imaging (QI) tools to improve pediatric tumor measurement, risk predictions and treatment response. Roger Packer, M.D., Senior Vice President of the Center for Neuroscience & Behavioral Health, Director of the Gilbert Neurofibromatosis Institute and Director of the Brain Tumor Institute, is co-investigator.

The project, in collaboration with Children’s Hospital of Philadelphia and Children’s Hospital Colorado, centers on the most common type of brain tumor in children, called a low-grade glioma. This project focuses on a clinically challenging group of children with neurofibromatosis type 1 (NF1), the most common inherited tumor predisposition syndrome. Nearly 20% of children with NF1 will develop a low-grade glioma called optic pathway glioma (OPG). In children with this type of brain tumor, the growth occurs around the optic nerve, chiasm and tracts, also called the optic pathway, which connects the eye to the brain. OPGs can cause vision loss and even blindness. Permanent vision loss usually occurs between one and eight years of age with doctors closely monitoring the tumor with magnetic resonance imaging (MRI) to assess the disease progression.

“Our traditional two-dimensional measures of tumor size are not appropriate to assess the changes in these amorphous tumors over time or how the tumor responds to treatment,” says Linguraru. “This means physicians have difficulty determining the size of the tumor as well as when treatment is working. Research such as this can lead to innovative medical technologies that can improve and possibly change the fate of children’s lives.”

Dr. Linguraru is leading the technical trials on this project, which take place in the first two years, or phase one, starting in June 2020. Phase one focuses on improving the often inaccurate human measurements of tumor size by developing QI tools to make precise and automated measures of tumor volume and shape using machine learning. In this phase, the project will use and homogenize MRI data from multiple centers to develop predictive models of the treatment response based on the tumor volume that are agnostic to the differences in imaging protocols. By doing this, it will allow physicians to make more informed decisions about the treatment’s success and whether the child will recover their vision.

When phase one is complete, Linguraru and the project’s other principal investigator Robert A. Avery, DO, MSCE, neuro-ophthalmologist in the Division of Ophthalmology at Children’s Hospital of Philadelphia, will initiate the second phase, which includes validating the QI application on data from the first ever phase III clinical trial comparing two treatments for NF1-OPGs. Phase two is scheduled to start in the Summer 2022 and continue through Summer 2025.

“For children who are at risk of losing their vision, this project will bring a window of opportunity for physicians to start treatment earlier and save their vision,” says Linguraru. “For those children who won’t benefit from chemotherapy because the tumor poses no threat to their sight, this project will save them from having to go through that difficult treatment unnecessarily. It will be life-changing for the children and their families, which is what excites me about this QI application.”

This project is a collaboration between Children’s Hospital of Philadelphia and Children’s National Hospital in Washington, D.C., in partnership with Children’s Hospital of Colorado and University of Pennsylvania. Upon project completion, the QI application will provide a precision-medicine approach for NF1-OPGs and improve clinical outcomes for pediatric tumors.

Malignant peripheral nerve sheath tumors

Clinical Trial Spotlight: Searching for effective therapies for malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas and the most common malignancy associated with neurofibromatosis type 1 (NF1).

Malignant peripheral nerve sheath tumors (MPNST) are aggressive soft tissue sarcomas and the most common malignancy associated with neurofibromatosis type 1 (NF1). Half of all MPNST are seen in NF1 patients, and MPNST is a leading cause of mortality in young patients with NF1. Researchers led by AeRang Kim, M.D., Ph.D., a pediatric oncologist at Children’s National Hospital, are now searching for a medical treatment for this rare disease that currently has dismal survival rates.

“Through consortia efforts, we’ve been able to open and accrue in single histology trials of really rare diseases such as MPNST for which there are no known curative therapies other than surgery, and surgery is very difficult or not feasible in many patients,” says Dr. Kim, the principal investigator for the SARC031 trial sponsored by the Sarcoma Alliance for Research through Collaboration. “In this trial in particular, our hope is to find a new therapy that will benefit patients with MPNST for which we have no known effective medical therapies.”

Using a combination of drugs that target specific pathways involved in MPNST growth, Dr. Kim and colleagues at four other institutions offering the SARC031 trial will monitor patients to see if the drugs shrink, slow down or stop the growth of MPNSTs. Based on preclinical data demonstrating substantial MPNST shrinkage in mice treated with a combination of MEK and mTOR inhibitors, SARC031 is a trial of the MEK inhibitor selumetinib in combination with the mTOR inhibitor sirolimus for patients with unresectable or metastatic MPNST. The primary objective is to determine the clinical benefit of the combination.

SARC031: A Phase 2 Trial of the MEK Inhibitor Selumetinib (AZD6244 Hydrogen Sulfate) in Combination with the mTOR Inhibitor Sirolimus for Patients with Unresectable or Metastatic Malignant Peripheral Nerve Sheath Tumors

  • PI: AeRang Kim, M.D., Ph.D.
  • Title: SARC031: A Phase 2 Trial of the MEK Inhibitor Selumetinib (AZD6244 Hydrogen Sulfate) in Combination with the mTOR Inhibitor Sirolimus for Patients with Unresectable or Metastatic Malignant Peripheral Nerve Sheath Tumors
  • Status: Recruiting

For more information about this trial, contact:

AeRang Kim, M.D., Ph.D.
202-476-2800
AeKim@childrensnational.org

Click here to view Open Phase 1 and 2 Cancer Clinical Trials at Children’s National.

The Children’s National Center for Cancer and Blood Disorders is committed to providing the best care for pediatric patients. Our experts play an active role in innovative clinical trials to advance pediatric cancer care. We offer access to novel trials and therapies, some of which are only available here at Children’s National. With research interests covering nearly aspect of pediatric cancer care, our work is making great advancements in childhood cancer.

How technology can predict vision loss in neurofibromatosis patients

Roger Packer and patient

For the first time, scientists have been able to definitively connect tumor volume and vision loss for children with neurofibromatosis type 1 (NF1). The first study to use quantitative imaging technology to accurately assess the total volume of individual optic nerve glioma (OPG) in NF1 was published in the November 4, 2016 issue of Neurology.

NF1 is a genetic condition that occurs in one in 3,500 births. Children with NF1 develop tumors in multiple locations across the nervous system. About 20 percent of children with NF1 will develop optic pathway gliomas, or tumors that occur in the visual system. Half of those with OPG will have irreversible vision loss, which occurs at a very young age, usually before age 3.

“Neuroradiologists typically assess these tumors through a measurement of the tumor’s radii using magnetic resonance images (MRI) of the patient,” said Marius George Linguraru, D.Phil., M.A., M.S., Principal Investigator in the Sheikh Zayed Institute for Pediatric Surgical Innovation at Children’s National Health System, who is senior author on the study.

“These measurements aren’t detailed enough to serve as a good indicator of whether an OPG will cause vision loss for a child. Through automated computerized analysis, however, we’ve taken the MRI data and systematically analyzed the size and shape, as well as documented changes over time, all in 3-D, to pinpoint the volume of each tumor.”

A look inside the study

The study included children with NF1-related OPGs who are currently cared for at the Gilbert Family Neurofibromatosis Institute at Children’s National. Investigators compared the MRI analysis to the patients’ retinal nerve fiber layer (RNFL), a measure of the health of the visual system. The analysis showed a quantifiable negative relationship between increasing tumor volume within the structures of the anterior visual pathway (the optic nerve, chiasm, and tract) and decreasing thickness of the RNFL, indicating damage to the visual system and vision loss.

“Measuring the tumors in a precise, systematic manner, along with knowing how they grow, is the first step in recognizing which children are at highest risk for vision loss and to potentially identifying them before they suffer any visual symptoms,” added Dr. Linguraru. “If we know which children will probably lose vision, we can treat earlier, and perhaps improve how patients respond to treatment.”

A multicenter collaborative study to validate the findings will begin in 2017.

Cancer update: tumor targeting, neurofibromatosis type 1 symptoms

June 6, 2016Targeting tumors more precisely, with fewer lasting side effects for kids
Pediatric patients with cancer are often treated with a cocktail of therapies to attack the disease through a variety of mechanisms. While this approach has been instrumental in saving children’s lives, the life-saving therapies can be accompanied by acute side effects, and the treatments may have lingering impacts as cancer survivors enter adulthood. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) holds the promise of surgically removing large tumors without exacting the same array of harsh side effects. Ultrasound relies on high-frequency sound waves to make diagnostic images, and those same sound waves can be used therapeutically to destroy tumors. Layering on MR imaging gives clinicians the ability to precisely guide the ultrasound therapy in real time. A study led by Children’s National Health System researchers and clinicians is using MR-HIFU for the first time in children to examine its safety and feasibility.

May 11, 2016 – Quantitative MRI criteria for optic pathway enlargement in neurofibromatosis type 1
Symptoms of neurofibromatosis type 1 (NF1) vary widely, but the condition is characterized by changes in skin pigmentation and growth of tumors along nerves. The research team sought to determine quantitative size thresholds for enlargement of the optic nerve, chiasm, and tract in children aged 0.5 to 18.6 years with NF1. The study, published in Neurology, found that quantitative reference values for anterior visual pathway enlargement will enhance development of objective diagnostic criteria for optic pathway gliomas secondary to NF1.