Researchers tested a medicine called denosumab on five children with rare bone tumors that are hard to remove with surgery. Denosumab is a type of drug that helps stop tumor growth by blocking certain signals in the body. The children received injections of this medicine over several months, and doctors found that four out of five kids had their tumors shrink significantly, while one child’s tumor stayed the same size. The treatment was safe and didn’t cause serious side effects. This small study suggests denosumab might be a helpful option for children with these difficult-to-treat bone tumors, though more research with more patients is needed to confirm these promising results.

The Quick Take

  • What they studied: Whether a medicine called denosumab could safely shrink rare bone tumors in children when surgery wasn’t possible
  • Who participated: Five children between ages 8 and 17 (two girls and three boys) with rare giant cell bone tumors that couldn’t be easily removed with surgery
  • Key finding: Four out of five children had their tumors shrink noticeably after receiving denosumab injections over several months, and one child’s tumor stayed stable. No serious side effects were observed.
  • What it means for you: If a child has a rare bone tumor that can’t be removed surgically, denosumab may be an option worth discussing with their doctor. However, this is based on a very small group of patients, so more research is needed before doctors can be fully confident about recommending it widely.

The Research Details

This was a case series study, which means doctors carefully tracked and reported what happened to five individual children who received denosumab treatment. The children were treated at one hospital in Italy between February 2022 and December 2023. Before starting the medicine, all children had blood tests to check calcium and vitamin D levels, and dental scans to look for any existing problems. This was important because denosumab can sometimes cause low calcium levels and jaw problems. The children received injections of denosumab under the skin at regular intervals—on days 1, 8, 15, and 28, then once a month for 3 to 5 months. Doctors then took imaging scans to see if the tumors had changed in size.

This research approach is important because these bone tumors are very rare in children, making it difficult to study large groups of patients. By carefully documenting what happened to each child, doctors can learn whether this medicine is worth testing in larger studies. The detailed tracking of side effects and tumor changes helps other doctors understand what to expect if they use this treatment.

This study is small (only five patients), which is a limitation. The results are promising but not definitive. The study was conducted at a single hospital, so the results may not apply to all children everywhere. The researchers acknowledge that longer follow-up (3-5 years) and studies with more patients from different hospitals are needed to confirm these findings. The fact that no serious side effects were seen is encouraging, but larger studies would give doctors more confidence about safety.

What the Results Show

Four of the five children showed significant shrinking of their bone tumors after receiving denosumab treatment. One child’s tumor remained stable (didn’t grow or shrink). The amount of tumor reduction was substantial enough that in one case, surgery became possible after the tumor had shrunk—something that wasn’t possible before treatment. The children received between 9 and 21 injections of the medicine over several months, and all tolerated the treatment well. No child experienced disease progression (worsening of the tumor) during the study period. The treatment was continued safely for up to 22 months in some cases, suggesting that long-term use doesn’t cause problems.

All children received supportive treatment with calcium carbonate and vitamin D supplements to prevent low calcium levels, which is a known possible side effect of denosumab. No cases of low calcium levels were actually observed in this group. No jaw problems (osteonecrosis) were detected in any of the children, despite this being a known risk. The dental scans performed before and during treatment showed no concerning changes. These secondary findings suggest that with proper monitoring and supportive care, denosumab can be used safely in children.

This study confirms what has been reported in smaller case reports and limited research about using denosumab in children with these rare bone tumors. Denosumab was originally approved by the FDA in 2013 for adults with giant cell bone tumors, but using it in children is considered ‘off-label’ (meaning it’s not officially approved for that age group, though doctors can still prescribe it). This research adds to the growing body of evidence suggesting that denosumab may be effective in pediatric cases, though the evidence is still limited.

The biggest limitation is the very small number of patients (only five). Results from five children cannot be confidently applied to all children with these tumors. The study only followed patients for about two years, but doctors recommend longer follow-up of 3-5 years to ensure the benefits last and no delayed side effects appear. The study was conducted at only one hospital, so results might differ in other settings or populations. Different children received different numbers of doses (ranging from 9 to 21), making it harder to determine the ideal treatment schedule. Without a comparison group of children who didn’t receive the medicine, it’s impossible to know if the tumor shrinkage was due to denosumab or other factors.

The Bottom Line

Based on this small study, denosumab appears to be a reasonable option for children with rare giant cell bone tumors that cannot be removed surgically. However, confidence in this recommendation is moderate because the study is very small. Parents and doctors should discuss whether denosumab is appropriate for their specific situation. Children receiving this treatment should have regular blood tests to monitor calcium and vitamin D levels, and dental check-ups to watch for any jaw problems. This medicine should only be used under the care of experienced pediatric oncologists (cancer doctors for children).

This research is most relevant to children diagnosed with giant cell bone tumors or giant cell granulomas that cannot be safely removed with surgery. Parents of children with these rare conditions should discuss this treatment option with their medical team. Pediatric oncologists and orthopedic surgeons treating children with bone tumors should be aware of this emerging treatment option. This research is not relevant to children without these specific bone tumors or to adults, who have different treatment options available.

Based on this study, tumor shrinkage was observed over several months of treatment (3-5 months of regular injections). However, the longest benefit was tracked over 22 months in one patient. Realistic expectations would be to see imaging changes within 3-6 months of starting treatment. The full long-term benefits and durability of response are not yet known and would require 3-5 years of follow-up to determine.

Want to Apply This Research?

  • If a child is receiving denosumab treatment, track monthly calcium and vitamin D blood test results, dental check-up dates, and imaging scan results (CT or MRI) to monitor tumor size changes. Record any side effects or symptoms, even minor ones, to discuss with the medical team.
  • Parents can use the app to set reminders for regular blood tests, dental appointments, and follow-up imaging scans. The app could help maintain a symptom diary to track any changes in pain, swelling, or other symptoms related to the tumor or treatment.
  • Establish a long-term tracking system that monitors calcium and vitamin D levels every 1-3 months, dental health every 3-6 months, and tumor imaging every 3-6 months initially, then potentially less frequently if stable. Track treatment adherence (whether injections are given on schedule) and any side effects over years, not just months, since the full safety profile requires longer follow-up.

This research describes a very small study (five patients) of an off-label medication use in children. These results are preliminary and should not be considered definitive evidence. Denosumab is not officially approved by the FDA for use in children, and using it in pediatric patients is considered off-label. Any decision to use denosumab in a child should only be made by experienced pediatric oncologists and orthopedic surgeons after careful evaluation of the individual child’s condition, risks, and benefits. Parents should discuss this treatment option thoroughly with their medical team, including potential side effects and the need for regular monitoring. This information is for educational purposes and should not replace professional medical advice.