(P 344) REAL-WORLD EXPERIENCE OF SORAFENIB IN DESMOID TUMOURS: A SINGLE-CENTRE AUSTRALIAN STUDY

Objective: Sorafenib (SFN) has demonstrated clinical efficacy in desmoid tumours (DT) per Gounder et al (NEJM 2018). This study aimed to evaluate the real-world efficacy and safety of SFN in DT within the Australian context.

Methods: We conducted a retrospective single-centre study to assess the real-world outcomes of SFN in DT. Response was evaluated using RECIST 1.1. An exploratory imaging endpoint using MRI T2-weighted signal intensity (T2SI) was also investigated as a response measurement, with a change of at least 30% in T2SI over time arbitrarily defined as significant.

Results: Between Jan 2022 and Feb 2025, 13 patients (pts) received SFN. Median age was 35 (range 23-53) years and 12 (92%) were female. 11 (85%) pts received SFN as first line systemic therapy. All pts commenced SFN at 400mg. At analysis cutoff with a median follow-up of 11.8 months, 8 (62%) pts remained on SFN, 5 pts had ceased due to completion of 12-month treatment (15%), toxicities (15%) or disease progression (8%). Median duration of treatment was 8.9 months (range 3.1-NR). Best overall response as per RECIST was 1 (8%) partial response, 9 (69%) stable disease and 3 (23%) progressive disease. Median progression-free survival (PFS) was 17.7 months (95% CI 3.7-NA) and estimated 1-year PFS rate was 75% (95% CI 50-99%). Based on T2SI, 6 (46%) pts had a significant reduction by 32% (median, range 30-84%), 5 (38%) had a non-significant reduction by 27% (median, range19-28%), 2 (15%) had a significant increase by 43% and 69% respectively in T2SI. Median PFS was 17.7 months (95% CI 3.7-NA) and estimated 1-year PFS rate was 84% (95% CI 63-100%). Most common adverse events were hand-foot syndrome (HFS, 54%, G1/2), mucositis (31%, G1/2), diarrhoea (31%, G1) and rash (31%, G1). Most common toxicities resulting in dose reduction were HFS (15%, G2), rash (15%, G2) and hypertension (8%, G2). Treatment cessations were due to multiple concurrent toxicities (G1/2 rash, fatigue, diarrhoea).

Conclusion: Our real-world data showed that SFN has clinically meaningful activity in DT with acceptable toxicities, though ongoing follow-up is required to determine longer term survival. T2SI may be a complementary response measurement to RECIST, further evaluation and correlation with clinical symptoms in a larger cohort is warranted.