St. Jude RT2CR Phase 2 Trial Demonstrates Proton Therapy Preserves Cognitive Function in Pediatric Craniopharyngioma
Study Background and Design
Craniopharyngioma is a rare pediatric brain tumor that occurs near the pituitary gland. Traditional gross total resection surgery carries a high risk of vision impairment and endocrine dysfunction. Researchers at the St. Jude Children's Research Hospital, led by Dr. Thomas E. Merchant from the Department of Radiation Oncology, designed the RT2CR (Radiation Therapy 2 for Craniopharyngioma) Phase 2 single-arm clinical trial (NCT01419067), combining limited surgery with proton therapy. From August 2011 to January 2016, 94 pediatric and adolescent patients (median age 9.39 years) were enrolled. They received a total of 30 fractions of proton therapy, five days a week, with weekly imaging monitoring. The study was supported by American Cancer Society, NCI (CA21765-23), and ALSAC.
Key Clinical Results
According to the results published in Lancet Oncology in April 2023, the 5-year progression-free survival (PFS) rate in the proton therapy group was 93.6%, and the 3-year overall survival (OS) rate was 100%. While there was no statistically significant difference in survival rates compared to the historical control group treated with photon therapy (5-year PFS ~90%), a key difference was observed in neurocognitive function. Patients treated with photon therapy experienced an additional annual decline of 1.09 IQ points and 1.48 points in adaptive behavior, whereas cognitive decline in the proton therapy group remained stable until the end of the study. Dr. Frederick Boop of St. Jude stated that these results are likely to become the 'gold standard' for the treatment of pediatric craniopharyngioma.
Treatment Paradigm and Competing Technologies
In the craniopharyngioma treatment market (estimated at USD 605 million in 2024 and USD 957.1 million in 2032, with a CAGR of 6%), proton therapy has secured a technological advantage by minimizing the dose to normal brain tissue due to its Bragg peak characteristic. Meanwhile, in papillary craniopharyngioma, the combination therapy of dabrafenib + trametinib, targeting BRAF V600E mutations, has achieved a tumor reduction rate of over 90%, emerging as a new competing treatment option. In the more common adamantinomatous type, WNT/Ξ²-catenin pathway inhibitors have entered early clinical stages in the United States and Europe.
Market Infrastructure and Equipment Industry Impact
The global proton therapy system market is projected to grow from USD 1.66 billion in 2025 to USD 4.09 billion in 2035, with an annual growth rate of 9.4%. IBA (IBAB.BR), Siemens Healthineers (SHL.DE, acquired Varian), Hitachi (6501.T), and Mevion Medical Systems are major equipment suppliers. Compact systems and AI-guided imaging technology are accelerating adoption. North America leads the market with a 43% share, and the Asia-Pacific region is the fastest-growing, with a CAGR of 12.5% in the CNS tumor segment.
The RT2CR trial demonstrated that proton therapy maintains a 5-year PFS of 93.6% and equivalent survival rates while significantly reducing annual IQ loss in pediatric craniopharyngioma, establishing a new standard for radiation therapy in pediatric brain tumors. The expansion of CNS tumor indications in the global proton therapy system market (USD 1.66 billion in 2025 to USD 4.09 billion in 2035, CAGR 9.4%) is expected to be a key driver of mid- to long-term revenue growth for equipment companies such as IBA and Siemens Healthineers. However, BRAF V600E targeted therapies (dabrafenib + trametinib) have achieved tumor reduction rates of over 90% in papillary craniopharyngioma, potentially partially replacing the demand for radiation therapy. From a researcher's perspective, a new evaluation criterion for neurocognitive preservation has been established, which will be a key precedent for transforming the overall paradigm of pediatric radiation oncology clinical trial design in the future.
Source: ClinicalTrials.gov (api_ct)