Abstract 150P
Background
Desmoid tumours (DT) are benign, although locally aggressive, monoclonal fibroblastic proliferations; despite their indolent pathology, their behaviour can be unpredictable and some cases can be very symptomatic. In those unresectable and symptomatic cases, sorafenib has shown some meaningful clinical activity compared to placebo in a phase III trial.
Methods
Retrospective cohort analysis of 19 patients with symptomatic DT treated with sorafenib as 1st-line treatment (2020-2023) until progression and/or unacceptable toxicity. Analysis of radiological response according to RECIST v1.1, toxicity rates according to CTCAE v5.0 and clinical response defined as radiological response and/or symptomatic improvement in pain after 4 months of treatment.
Results
19 patients, 62.5% female. Median age 37 years (range 18-80 years). Familiar adenomatous polyposis in 31.3%. Retroperitoneal in 25%, limbs in 18.8%, abdominal wall in 50%, head and neck region 6.3%, 50% de novo disease. All patients symptomatic and deemed unresectable without undue morbility. Overall response rate of 43.8% (37.5% partial response and 6.3% complete response), stable disease in 49.1%; only 1 progression (5.3%). 75% reported toxicity, 68.75% grade 1-2 and 18.75% grade 3. The most frequent toxicity seen was fatigue (50%) and palmo-plantar erythrodisestesia (31.25%). 2 patients required dose reduction and 1 patient treatment interruption due to toxicity. Clinical benefit was seen in 77.8% of patients, in most cases secondary to an improved analgesic control. 68.75% of patients reported clinical improvement in pain after four months of treatment, with less analgesic requirements or even suspension of all painkillers. No patients needed third-step opioid treatment after sorafenib introduction.
Conclusions
In our series, sorafenib is a useful and cost-effective treatment for patients with symptomatic DT. Most patients had a radiological response and symptomatic progression was very uncommon. Clinical benefit was seen in a higher percentage of patients compared to the radiological benefit; RECIST criteria may not be the best way to evaluate these responses. We observed a lower grade 3-4 toxicity rate compared to the pivotal phase III, which was easily manageable.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.