Systemic treatments for desmoid tumours (also known as aggressive fibromatosis) include hormonal blockade, cytotoxic chemotherapy and tyrosine-kinase inhibitors, although response rates to these treatments are varied and no standard-of-care therapy has been defined. A prospective study now shows that sorafenib can slow the progression of this disease.

In a double-blind phase III trial, 87 patients with progressive, symptomatic or recurrent desmoid tumours were randomly assigned to treatment with sorafenib (n = 50) or matched placebo (n = 37). The primary end point was investigator-assessed progression-free survival (PFS) according to the Response Evaluation Criteria in Solid Tumors (RECIST).

At a median follow-up duration of 27.1 months, the median PFS was not reached in the sorafenib group versus 11.3 months in the placebo group; the estimated 2-year PFS was 81% versus 36% (HR 0.13; 95% CI 0.05–0.31; P < 0.001). These data indicate an 87% reduction in the risk of progression or death with sorafenib.

Notably, the benefit of sorafenib did not seem to be dependent on achieving an objective response (objective response rate of 33% compared with 20% in the placebo group). Interestingly, 167 MRI scans from 11 patients were analysed to compare changes in tumour dimensions (according to RECIST) with changes in total tumour volume and in MRI T2-weighted signal intensity (which indicates a change from a cellular tumour to a collagenous scar). The results indicate that the latter measures might be more efficient than RECIST in assessing treatment efficacy in patients with desmoid tumours.

Grade 3–4 adverse events occurred in 47% of patients in the sorafenib group and in 25% of patients in the placebo group. With sorafenib, the most frequent adverse events were grade 1–2 rash (73%), fatigue (67%), hypertension (55%) and diarrhoea (51%). In summary, sorafenib seems to effectively slow the progression of desmoid tumours.