Kids with Rare Thyroid Cancers: Selpercatinib's Accelerated Approval

Introduction to Selpercatinib

The FDA has given the green light for accelerated approval of selpercatinib, also known as Retevmo. This drug is designed to treat children aged 2 and older who have advanced forms of thyroid cancer or other solid tumors characterized by a specific genetic mutation in the RET gene.

Why This Approval is Significant

This approval is particularly important because it provides a new treatment option for children who have limited alternatives. Traditional treatments may not always be effective, making it crucial to have new medications available. Selpercatinib is filling that gap, offering hope for families dealing with challenging cancer diagnoses.

Clinical Trials and Success Rates

The efficacy of selpercatinib was tested in a clinical study called LIBRETTO-121. During this trial, researchers found that the drug had a success rate of 48% in terms of overall response, meaning that about half of the patients had a significant reduction in tumor size.

Among children with RET-mutated medullary thyroid cancer, the drug showed a response rate of 43%. Even more impressive, 67% of these patients experienced a duration of response lasting at least 18 months.

Focus on RET Fusion-Positive Thyroid Cancer

The study also involved children with RET fusion-positive thyroid cancer. Here, the success rate was even higher at 60%. Specifically, 83% of these patients had a response that lasted for over a year, and 50% had responses lasting 18 months or more.

Enrollment Criteria for the Study

For the LIBRETTO-121 study, children and young adults with advanced or metastatic solid tumors were eligible if they had a specific genetic alteration in the RET gene. They also needed to have a good performance score and various acceptable health indicators to participate.

Exclusion Criteria and Safety Measures

There were strict criteria excluding children with recent surgeries or specific unmanaged health conditions, such as serious heart diseases or infections. This was to ensure safety and reliable results from the study.

Dosing and Administration

Participants took an oral dose of 92 mg/m² of selpercatinib twice a day. Treatment continued until the disease progressed, side effects became intolerable, or other stopping criteria were met.

Phase 1 and Phase 2 Objectives

The first phase aimed to check the safety and determine any dose-limiting side effects. The second phase focused on evaluating the success of the treatment using specific clinical criteria.

Common Side Effects

Common side effects included muscle pain, diarrhea, headache, nausea, and vomiting. Some patients also experienced serious lab abnormalities, such as low calcium or neutrophil levels.

Conclusion

The accelerated approval of selpercatinib marks an encouraging development in pediatric oncology. It provides a promising treatment option for young patients with rare thyroid cancers and other solid tumors that have specific genetic mutations.