The CHAMP-study: The CHemopreventive Effect of Lithium in Familial AdenoMatous Polyposis

Rationale: Familial adenomatous polyposis (FAP) syndrome is characterized by the development of numerous colorectal polyps. If left untreated, these patients have a chance of nearly 100% of developing colorectal cancer (CRC) at a young age. Therefore, guidelines recommend a prophylactic colectomy during early adulthood. Even after colectomy, most patients will develop adenomas in the retained rectum or ileoanal pouch requiring further endoscopic surveillance. In a recent study in mouse models, a chemopreventive effect of Lithium was observed on the spread of Apc mutated cells within the crypts of normal intestinal mucosa, suggesting polyp formation can be prevented. Lithium is used to treat patients with bipolar disorders but has never been investigated in patients with FAP aiming to reduce polyp burden. We hypothesize that Lithium could reduce the spread of APC mutated cells within the crypt of normal intestinal mucosa potentially reducing polyp burden in patients with FAP. Objective: The aim of this study is to investigate the effect of low-dose Lithium on stem cell dynamics, the number and size of polyps and, to assess safety outcomes of this drug in FAP patients. Study design: A prospective phase II, single arm pilot trial, with a duration of 18 months. The drug will be administered between month 6 and 12. Study population: Twelve patients with FAP between the age of 18 and 35 not having undergone a colectomy (yet), having a genetically confirmed APC mutation and a family history with a classical FAP phenotype. Intervention: All patients will be treated with Lithium with an oral dose of 300mg a day for six months, achieving a therapeutic serum level between 0.2-0.4 mmol/L. Main study parameters/endpoints: The main outcome parameter is the effect of Lithium on the spread of APC mutant cells within intestinal crypts over time by using an APC specific marker NOTUM (a significance reduce of fixed crypts and reduction of fixed clone size of 50%). Nature and ext