149P Treatment landscape for desmoid tumors: Desmoid Tumor Research Foundation Natural History Study

Patients with desmoid tumors (aggressive fibromatosis) have several treatment options, and individual experiences are vast and varied. This analysis describes the treatment landscape for patients with desmoid tumors after diagnosis. This is a descriptive analysis of the global, survey-based Desmoid Tumor Research Foundation (DTRF) Natural History Study using data collected from Sept 2017 to Aug 2023. Participants and/or their caregivers reported desmoid tumor diagnosis and treatment. The N values vary for these analyses due to incomplete data. Of the 383 participants who completed the treatment survey (median age, 39 years), 58% (223/383) reported having a current tumor. Among the 43% (163/383) of participants who received surgery to treat desmoid tumors, 63% (103/163) reported subsequent continued tumor growth or recurrence. Among those who responded to surgical questions, 43% (50/115) reported receiving surgery both before and after a confirmed diagnosis. Surgery was reported as the 1st-line treatment for 59% (74/126) of participants who received multiple lines of treatment. 76% (281/369) of participants received systemic therapy after diagnosis, including NSAIDS (40%), tyrosine kinase inhibitors (32%), chemotherapeutics (31%), and hormone antagonists (17%) (Table). Participants reported continued tumor growth whether they received prior treatment (43%; 92/216) or not (54%; 70/129). Table: 149PSystemic therapies (any line; N = 281)N (%)Chemotherapeutics87 (31)Methotrexate32 (37)Vinblastine26 (30)Doxorubicin (or loxorubicin)25 (29)Liposomal doxorubicin (or Doxil)25 (29)Dacarbazine7 (8)Vinorelbine6 (7)Hydroxyurea2 (2)Ifosfamide2 (2)NSAIDs (inc. sulindac and celecoxib)112 (40)NSAIDs (not otherwise specified)51 (46)Sulindac46 (41)Celecoxib23 (21)Tyrosine kinase inhibitors91 (32)Sorafenib64 (70)Imatinib26 (29)Pazopanib9 (10)Sunitinib1 (1)Hormone antagonists47 (17)Antihormonal agent (eg, tamoxifen)41 (87)Toremifene4 (9)Anastrozole2 (4)Gamma secretase inhibitor3 (1)Other (eg, rituximab)57 (20) Open table in a new tab Surgery was the most prevalent 1st-line therapy for participants with multiple treatments, with a high rate of recurrence after surgery. No trends were reportedfor use of systemic treatments. With the FDA approval of nirogacestat for the treatment of desmoid tumors, clear guidelines for sequencing surgery and systemic therapies are needed for optimum patient care.