Summary: 131I-Omburtamab is a radiolabelled monoclonal antibody showing promising results in treating neuroblastoma, particularly in cases with central nervous system (CNS) and leptomeningeal metastasis. Granted Orphan Drug Designation by the European Medicines Agency and Breakthrough Therapy Status by the U.S. FDA, this novel treatment has demonstrated significant improvements in patient survival rates. This article explores the development, clinical trials, and future prospects of 131I-Omburtamab.
Introduction to Iodine-131 Omburtamab
Neuroblastoma is a malignant tumour arising from neural crest cells, predominantly affecting infants and young children. It is notorious for its aggressive nature and tendency to metastasise, particularly to the central nervous system (CNS) and leptomeninges. Traditional treatments often fall short in managing refractory cases, highlighting the need for innovative therapies. Enter 131I-Omburtamab, a radiolabelled monoclonal antibody targeting the B7-H3/CD276 antigen, offering new hope for patients with advanced neuroblastoma.
131I-Omburtamab: A Novel Therapeutic Approach
131I-Omburtamab, also known as 131I-Burtomab or 131I-8H9, is a murine monoclonal antibody labelled with iodine-131, a radioactive isotope emitting beta particles (β–). The antibody specifically targets B7-H3/CD276, a protein overexpressed in various tumours, including neuroblastoma. By binding to this antigen, 131I-Omburtamab delivers targeted radiation to cancer cells while sparing healthy tissue.
Regulatory Milestones
In March 2017, the European Medicines Agency (EMA) designated 131I-8H9 as an Orphan Drug for treating refractory leptomeningeal metastasis from neuroblastoma. This status facilitates the drug’s development by providing incentives such as market exclusivity and reduced regulatory fees.
Following this, in June 2017, the U.S. Food and Drug Administration (FDA) granted 131I-Omburtamab Breakthrough Therapy Status for second-line or greater therapy in metastatic neuroblastoma in neonates and children. This designation accelerates the development and review process, recognising the drug’s potential to address unmet medical needs.
Clinical Development and Trials
CNS/Leptomeningeal Metastasis from Neuroblastoma
131I-Omburtamab is currently in Phase II clinical trials for treating CNS and leptomeningeal metastasis from neuroblastoma. The trials focus on patients who have not responded to conventional therapies, assessing the drug’s efficacy and safety profile.
Desmoplastic Small Round Cell Tumour (DSRCT)
In addition to neuroblastoma, 131I-Omburtamab is undergoing Phase I trials for treating Desmoplastic Small Round Cell Tumour (DSRCT), a rare and aggressive malignancy occurring in the peritoneum. Early studies aim to determine the optimal dosing and evaluate preliminary efficacy.
Imaging Agent 124I-Omburtamab
An integral part of the treatment protocol is the use of 124I-Omburtamab, an imaging agent labelled with iodine-124. This diagnostic tool helps identify patients likely to respond positively to 131I-Omburtamab therapy. By imaging the distribution of the antibody within the body, clinicians can tailor treatment plans to maximise efficacy.
Clinical Outcomes and Efficacy
Results from pivotal studies are highly encouraging. Patients treated with 131I-Omburtamab for refractory leptomeningeal metastasis from neuroblastoma showed an average survival of 58 months, a stark contrast to the 4.7-month average survival in a contemporary cohort receiving standard care.
Moreover, long-term follow-up data over more than a decade indicate an overall survival rate exceeding 40% at 15 years, suggesting that a significant proportion of treated children may achieve a cure. These findings underscore the potential of 131I-Omburtamab to transform outcomes for patients with this challenging condition.
Future Directions
Expansion to Other Tumours
Recent studies have initiated the exploration of 131I-Omburtamab in other malignancies. Trials involving patients with recurrent medulloblastoma and ependymoma, as well as solid tumours in the peritoneum, are underway. These efforts aim to broaden the therapeutic applications of the drug beyond neuroblastoma.
Humanised 8H9 Antibody
To mitigate immune responses against the murine antibody, a humanised form of 8H9 is under development. Humanisation reduces the likelihood of immunogenicity, potentially improving the drug’s safety and effectiveness in long-term use.
Mechanism of Action
Targeting B7-H3/CD276
B7-H3/CD276 is an immune checkpoint molecule overexpressed in various cancers. It plays a role in tumour immune evasion, making it an attractive target for therapy. 131I-Omburtamab binds to this antigen, facilitating direct delivery of radioactive iodine to tumour cells.
Beta Radiation Therapy
The beta electrons (β–) emitted by iodine-131 cause DNA damage within cancer cells, leading to cell death. This form of radiation therapy is highly effective when precisely targeted, as it minimises exposure to surrounding healthy tissues.
Conclusion
Iodine-131 Omburtamab represents a significant advancement in the treatment of neuroblastoma, particularly for patients with CNS and leptomeningeal metastasis who have limited options. Its targeted approach and impressive clinical outcomes offer renewed hope for long-term survival and potential cure. Ongoing research and development, including trials in other cancers and the creation of a humanised antibody, may further enhance its therapeutic impact.
You are here: home »