Desmoid tumors in familial adenomatous polyposis: A pilot project evaluating efficacy of treatment with pirfenidone

OBJECTIVE: Pirfenidone (Deskar, Marnac Inc., Dallas, TX), 5-methyl-1-phenyl-2-(1H)-pyridone, is a broad-spectrum, noncytotoxic, oral antifibrotic agent that is reported to inhibit or block the action of cytokine growth factors: transforming growth factor β1, platelet-derived growth factor, epidermal growth factor, and fibroblast growth factor, and to prevent formation of new fibrotic lesions. METHODS: We enrolled 10 women and four men with extensive familial adenomatous polyposis (FAP)-associated desmoid disease in a 2-yr open-label treatment trial with oral pirfenidone. Imaging of desmoids was conducted at baseline and 6, 12, and 24 months. RESULTS: No drug toxicity or drug intolerance was encountered. Seven patients dropped out (three because of progressive disease), and seven continued for at least 18 months. Of those that continued, two had partial but significant reduction in the size of all desmoids beginning in the first 6 months of treatment, and two others experienced relief of symptoms without change in desmoid size. Three patients experienced no change in tumor size or symptoms. CONCLUSION: Pirfenidone is well tolerated by patients with FAP-associated desmoid tumors. Some patients with FAP/desmoid tumors treated with pirfenidone had regression of tumors, some had progression, and some had no response. Patients with rapidly growing tumors did not respond to pirfenidone. A placebo-controlled trial is needed to determine whether there is a subset of patients for whom pirfenidone may result in partial shrinkage of desmoid tumors, because the natural history of desmoid tumors is not predictable or understood.