Crohn's Disease (CD) and Ulcerative Colitis (UC) are chronic inflammatory bowel diseases (IBD). Adalimumab is a human monoclonal antibody against TNF-alpha, a pro-inflammatory cytokine that mediates the inflammatory response in IBD upon binding to the TNF receptors. Primary non-response to adalimumab is high in both CD and UC. Currently, there are no predictors of response to adalimumab and the actual mechanism of action has not yet been elucidated. To gain better understanding of the drug targeting of adalimumab in IBD, the University Medical Center Groningen (UMCG) developed fluorescently labeled adalimumab (adalimumab-680LT). This study aims to assess the safety and the optimal dose of adalimumab-680LT to visualize and potentially quantify the local drug concentration and predict treatment response in IBD patients using in vivo and ex vivo fluorescence molecular imaging (FMI).

Inclusion Criteria:

• Established IBD diagnosis (UC or CD)
• Active disease (clinically defined as at least mild activity using dedicated scoring indices and biochemically defined by a fecal calprotectin > 60 µg/g, measured within the last 6 weeks before inclusion)
• Patients must be eligible for adalimumab therapy
• Clinical indication for an endoscopic procedure
• Age: 18 years or older
• Written informed consent
• For female patients of premenopausal age with intact reproductive organs or who are less than 2 years postmenopausal, a negative pregnancy test must be available.

Exclusion Criteria:

• Pregnancy or breast feeding
• Female patient of premenopausal age who does not use any reliable form of contraception at the time of adalimumab-680LT administration and the following 10 weeks.
• Medical or psychiatric conditions that compromise the patient's ability to give informed consent
• Prior anti-TNF therapy in the last 6 weeks before inclusion
• Active extra gastrointestinal manifestations of Crohn's disease
• Previous treatment with adalimumab and detectable anti-adalimumab antibodies levels