SUMMARY Rationale: Due to the presence of numerous colorectal polyps, nearly all patients with familial adenomatous polyposis (FAP) develop colorectal cancer (CRC) at an average age of 45 years, if left untreated. Therefore, a prophylactic colectomy is recommended. After surgery, adenomas are likely to reappear in the pouch or rectum. Recently, studies in APC-deficient mice have shown that the mTOR inhibitor sirolimus can cause intestinal tumour cells to undergo growth arrest and differentiation and could even lead to regression of polyps. In current practice, sirolimus is used as an immunomodulator for patients after renal transplantation. Sirolimus has never been investigated in patients with FAP. The hypothesis of the study is that sirolimus could lead to regression of intestinal polyps in patients with FAP.~Objective: The aim of the study is to investigate the effect of sirolimus on the progression of intestinal adenomas in patients with FAP and to assess the safety of this treatment.~Study design: A prospective phase II pilot study with a follow-up of 6 months. Study population: Five patients with FAP will be selected and invited for study participation. Patients need to be 18 years or older, have a genetically confirmed APC mutation with a classical FAP phenotype and a subtotal colectomy with an ileo-rectal anastomosis (IRA) or a total colectomy with an ileo-anal pouch anastomosis (IPAA) with severe polyposis.~Intervention: All patients will receive sirolimus for the duration of the study, with a trough level target range of 5-8 ng/ml.~Main study parameters/endpoints: The main study parameters are the effect of sirolimus on the size of 5 marked polyps and safety of this treatment. Safety outcomes will be assessed by summary analysis of adverse events, clinical laboratory abnormalities and regular physical examination. Additional parameters are the effect on the number of polyps, global polyp burden, histopathology and patient-reported quality of life. Cell proliferation and immunohistochemistry of mTOR targets in healthy intestinal mucosa and adenomatous tissue will be assessed.~Nature and extent of the burden and risks associated with participation, benefit and group relatedness: At baseline and at three monthly visits a medical history will be taken and physical examinations will be performed, as well as laboratory tests and HRQoL questionnaires. Trough level testing of sirolimus will be measured at day 7 after start of the study drug and weekly until the therapeutic range has been achieved, after which the next trough level will be measured at 3 and 6 months follow-up. Finally, monthly telephone check-ups will be carried out. LGI endoscopies will be done at baseline and at 6 months. For this study, patients are included with severe rectal or pouch polyposis as they are expected to have an indication for invasive surgery on a short-term base and no other less invasive alternative therapy is available.
The aim of the study is to investigate the effect of sirolimus on the progression of intestinal adenomas in patients with FAP and to assess the safety of this treatment.