Low Dose IL-2 for Ulcerative Colitis

Interleukin-2 (IL-2) is a T cell growth factor. IL-2 is currently licensed for the treatment of metastatic renal cell carcinoma and metastatic melanoma, where it promotes the expansion of anti-cancer cytotoxic T cells and natural killer (NK) cells. However at low doses (100-times lower than those used in cancer therapy), IL-2 promotes the selective expansion of regulatory T cells (Tregs): an immune modulating subset of CD4+ lymphocytes. A recent phase 1 clinical trial from our collaborators at the Dana Farber Cancer Institute showed that low-dose IL-2 selectively expands Tregs in patients with treatment-resistant Graft vs. Host Disease (GvHD), and that low-dose IL-2 is safe in this condition. A detailed immunological analysis of samples from this study showed that low-dose IL-2 treatment was associated with increased Treg proliferation, increased de novo thymic generation of Tregs, and a resolution of defects in intracellular signalling and apoptosis seen in Tregs in chronic GvHD. A recent phase 1 study from another group showed that low-dose IL-2 is safe in the treatment of HCV-associated vasculitis. Low-dose IL-2 has also been shown to be well-tolerated in subjects with HIV. Ulcerative colitis (UC) is a chronic inflammatory disease of the colon. Evidence from pre-clinical models of intestinal inflammation, and also from patients with monogenetic defects in Treg function, suggests that Tregs play a role in the prevention of inflammation in the intestine. The treatment (or intervention) in this study is a once-daily, subcutaneous injection of IL-2, for a total of 8 weeks. The first 2 doses of the study drug will be administered by research nurses at Boston Children's Hospital. Further doses will be self-administered, at home. Training will be provided for correct self-administration. This is a 3+3 dose escalation study of IL-2 in moderate-to-severe UC. This study design is powered to identify the MED of low-dose IL-2 in UC. Once the MED is identified, a further 10 subjects will receive IL-2 at that dose. Recruitment of between 2 and 28 patients is planned. The maximum tolerated dose (MED) is the highest tolerated dose level at which a minimum of 6 subjects have been evaluated, with fewer than 2 evaluable subjects in 6 experiencing a dose limiting toxicity (DLT); i.e. DLT in >1/6 evaluable subjects. In addition to the above at least 1 patient should meet the criteria for response or remission for it to be considered the MED. Dose levels are based on the experience of our collaborators in GvHD. In addition to determining the MED, this study will determine if low-dose IL-2 is safe and well-tolerated in patients with moderate-to-severe ulcerative colitis. A detailed immunological analysis of samples obtained from this study will determine if low-dose IL-2 expands Tregs in vivo, in patients with moderate-to-severe UC. Immunological changes will then be correlated with clinical response. The study will take place at Boston Children's Hospital. The study will involve 10 study visits. Most of the study visits involve blood tests. A flexible sigmoidoscopy or colonoscopy will be performed as part of the screening process. A flexible sigmoidoscopy will also be performed on completion of therapy, to determine clinical response. The first two subjects to receive the study drug will be admitted overnight following the first dose. Subsequent doses will be administered on an out-patient basis. All other subjects will receive IL-2 on an out-patient basis. Responders (with an acceptable side-effect profile) will be allowed to continue the study drug for at least 1 year. Compensation will be provided for participants.