Innovative Targeted Radiation Therapy Achieves Near-Complete Response in Rare Sarcoma Cases

Recent advancements in targeted radiation therapy have demonstrated promising results in treating a rare type of malignant tumor known as solitary fibrous tumor (SFT). In a small study involving three patients, this novel approach resulted in near-complete tumor responses, significantly reducing cancer activity and alleviating symptoms such as fatigue and abdominal pain. The therapy involved delivering radiation directly to the tumor’s fibroblast activation protein (FAP), which is highly expressed on tumor cells and surrounding fibroblasts.

The patients had previously undergone multiple standard treatments without success. Advanced FAPI-46 PET imaging confirmed high levels of FAP expression in their tumors. They then received four cycles of radioligand therapy using Yttrium-90 FAPI-46, and their responses were monitored through PET/CT scans with FAPI-46 and FDG tracers. All three patients experienced tumor shrinkage or stabilization, along with notable symptom relief, and importantly, no serious side effects were reported.

SFT is a rare soft tissue tumor with limited treatment options. While most are benign with low recurrence risk, 15-20% are malignant, and those classified as benign can potentially transform malignantly. For malignant cases, prognosis is often poor due to scarce effective therapies.

Helena Lanzafame, MD, from the Department of Nuclear Medicine at University Hospital Essen, explained that FAP is highly expressed in several sarcomas, including SFT, and delivering targeted radiation via radioligands like Y-90 FAPI-46 represents a promising therapeutic strategy. The study's early results suggest that screening patients for FAP expression could help identify those most likely to benefit from this precise treatment.

While these initial findings are encouraging, researchers emphasize that larger clinical trials are necessary to verify safety and efficacy, and to determine how best to incorporate this therapy into existing treatment protocols. This breakthrough offers hope for patients with limited options and highlights the potential of precision radioligand therapy for rare sarcomas.

Source: https://medicalxpress.com/news/2025-09-therapy-response-rare-sarcoma-patients.html