For most newly diagnosed desmoid tumors, the standard of care has shifted to active surveillance. This is because approximately 50% remain stable and up to 25% may regress spontaneously, avoiding the need for immediate active treatment.
Treatment algorithms for desmoid tumors are highly dependent on tumor location. While medical therapy is preferred for mesenteric or head and neck tumors to avoid morbidity, surgery remains a viable first-line option for the specific case of abdominal wall tumors.
Long-term data from the DEFI trial shows continuing niragasestat beyond one year increases overall response rates from 34% to 46%. Counterintuitively, the incidence and severity of common side effects like diarrhea and nausea tend to diminish after the first year of treatment.
A key disconnect exists between clinical and radiological response to niragasestat. Patients often experience rapid symptomatic relief, such as pain reduction, within days or weeks. Clinicians should expect a significant delay before seeing tumor shrinkage on imaging, with a median time to response of 5.6 months.
While ovarian toxicity affects approximately 75% of premenopausal women taking niragasestat, the effect is largely reversible. Clinical trial data shows a 100% resolution rate upon drug discontinuation and, surprisingly, a two-thirds resolution rate even among patients who continue treatment.