Breakthrough progress and global practice analysis of selumetinib in the treatment of neurofibromatosis type 1

In recent years, with the rapid development of precision medicine around the world, the treatment of rare diseases in children is ushering in major breakthroughs. Selumetinib hydrogen sulfate capsules (KOSELUGO, trade name: Kesaiyou), as the first targeted MEK inhibitor for the treatment of neurofibromatosis type 1 (NF1) plexiform neurofibromas (PN), have been officially launched in China and entered medical insurance, which has greatly improved the accessibility of treatment for patients. In 2025, as updated overseas NF1 research and MEK inhibitor strategies continue to be announced, selumetinib is at the forefront of the treatment of children's genetic diseases.

1. After selumetinib entered the medical insurance:Fundamental changes in the treatment pattern of NF1

The biggest development after selumetinib was launched in China is its inclusion in the national medical insurance directory. NF1 is a rare genetic disease. In the past, there was a lack of effective drugs, and patients often needed to rely on surgery, observation and waiting, and symptomatic treatment. After being covered by medical insurance, the financial burden on families has been significantly reduced, which has also promoted more domestic medical institutions to establish NF1 standardized outpatient clinics.

At the same time, the liberalization of medical insurance has enabled more children to receive interventional treatment at an early stage of the disease, which is of key significance for inhibiting the continued growth ofPN, reducing pain, and protecting important nerve and organ functions. Clinical trends show that the earlier the treatment is started, the more stable the intervention effect will be. Especially for PN with rapidly growing symptoms, timely medication may reduce irreversible functional damage in the later period.

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II, The scientific logic of MEK inhibitors: Why can selumetinib become a breakthrough in NF1 treatment?

The core of the pathogenesis of NF1 plexiform neurofibromas lies in the sustained activation of the RAS/MAPK pathway. The tumor is not a typical malignant tumor, but a genetic defect that causes cell proliferation signals to go out of control, forming a large mass with diffuse borders that is difficult to surgically remove.

Key points of selumetinib’s mechanism of action:

It directly inhibits MEK1/2 enzyme, reducing abnormally active signaling pathways.

Reduce the growth motivation of tumor cells from the source, rather than simply killing the cells.

Because the mechanism targets pressure regulatory signals rather than chemotherapy-like toxicity mechanisms, it is more suitable for long-term use.

In recent years, international studies have also pointed out that selumetinib may affect the tumor stromal microenvironment, including reducing inflammatory activity and reducing the number of tumor stromal cells. This may be the reason why some patients find pain relief. Exploration at these mechanistic levels provides an important scientific research foundation for the next generation of NF1-targeted drugs.

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III. Indications of selumetinib——"Core treatment plan for NF1 plexiform neurofibromas"

On September 10, 2025, the US FDA approved selumetinib granules and capsules for use in pediatric NF1 patients 1 year old and above. These patients need to have the following characteristics:

A clear diagnosis Neurofibromatosis type 1 (NF1);

Presence of symptomatic, inoperable plexiform neurofibroma (PN);

The tumor has affected daily life, such as pain, limited activities, facial changes, etc.;

The tumor is located in areas with extremely high surgical risks or that cannot be completely removed, such as the brain, neck, and paraspinal areas.

Judging from the latest clinical practice, many centers no longer only use "inoperable" as the only criterion, but also include "tumor growth too fast" as an early indication for initiating treatment. This means that more children in the future can be intervened before the risk of disease increases to reduce functional damage.

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IV. Usage and dosage of selumetinib: precise dosing mode based on body surface area (BSA)

Although selumetinib is an oral drug, its administration method needs to be adjusted according to the child's**Body Surface Area (BSA)**, so its medication strategy reflects the characteristics of "precision dose management".

Both international guidelines and the latest domestic consensus point out:

The recommended dose is 25mg/m², taken orally twice a day (about once every 12 hours); it needs to be taken on an empty stomach to avoid fluctuations in absorption caused by eating: avoid eating 2 hours before administration; After administration No eating within 1 hour

The following is based on Common clinical dosage intervals of BSA:

BSA<0.55 m²: No standard dose recommendation; 0.55-0.69 m²: 20 mg in the morning, 10 mg in the evening; 0.70-0.89 m²: 20 mg, twice a day; 0.90-1.09 m²: 25 mg, twice a day; 1.10-1.29 m²: 30 mg, twice a day; 1.30-1.49 m²: 35 mg twice daily; 1.50-1.69 m²: 40 mg twice daily; ≥1.70 m²: 45-50 mg twice daily.

Some studies have pointed out that not all patients need to be maintained at the maximum dose, and some people with sensitive constitutions can still achieve tumor shrinkage or stabilization after dose reduction, which provides ideas for future dose optimization.

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5. Global price differences of selumetinib and the influence of generic drugs

Original drug:

The specifications of the drugs sold in China include 10mg*60 pills and 25mg*60 pills. The price of each box may be around 20,000 yuan. China's medical insurance policy is reimbursed through the Category B Catalog, which significantly reduces the patient's out-of-pocket ratio, but the specific reimbursement ratio is subject to the regulations of the local medical insurance bureau;

The price of the original drug in the European Union fluctuates due to the exchange rate. 10mg*60 tablets is about more than 50,000 yuan.

Generic drugs: Laos Lucius Pharmaceuticals10mg 60 tablets is about 2,000 yuan, 25mg 60 tablets is about 3,000 yuan. The popularity of generic drugs provides an economic choice for self-pay patients, but they need to be purchased through formal channels and the batch number verified to avoid the risks of illegal channels.

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6. Medication management trends of selumetinib: Children’s families pay more attention to standardized dosing and compliance

Although the instructions recommend adjusting the dose according to body surface area (BSA), in clinical practice more attention is paid to:

How to Reduce Gastrointestinal Discomfort

How to take medicine regularly on an empty stomach

How to reasonably arrange medication time in school life

How to deal with mild skin symptoms to avoid affecting your quality of life

Some overseas children's hospitals have even launched Family support programs, including reminder systems, dietary management suggestions, and regular remote follow-up to improve long-term compliance. Similar models have also begun to be built in China, especially in large children's hospitals.

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7.GlobalNew trends in NF1 research: More people are paying attention to safety solutions that can be used for a long time

In the past year, several research directions on selumetinib have received particular attention:

1. “Is it safe for long-term use?” has become the focus of international research

NF1 is a chronic, lifelong disease, so long-term intervention strategies are critical. Data from multiple overseas centers show that children who use selumetinib for a long time need continuous attention in terms of weight gain, heart function, and ophthalmological monitoring. International guidelines increasingly recommend the development of an annual systematic monitoring program, with particular emphasis on:

Left ventricular function monitoring

Intraocular pressure and lens examination

changes in liver function

Growth and Development Tracking

These trends have pushed domestic hospitals to incorporate NF1 into the "long-term follow-up system for rare childhood diseases".

2. Researchers are concerned about “whether the tumor will grow again after stopping the drug”

Some studies have found that PN may increase at an accelerated rate after stopping treatment, so the decision to discontinue treatment requires individualized assessment. The global trend is to maintain tumor stability through retreatment, which is of great significance to medical insurance coverage.

3. Exploration of the latest combination treatments

Starting in 2025, multinational research teams will try the combination of selumetinib:

Novel anti-inflammatory modulator

OthersMAPK pathway inhibitors

Immune pathway related drugs

These combination options are still in the research stage, but they provide more possibilities for long-term management of NF1.

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References:

https://www.fda.gov/drugs/resources-information-approved-drugs

https://www.thelancet.com/journals

https://www.ema.europa.eu/en/medicines

https://www.ncbi.nlm.nih.gov/pmc/articles

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