The scientific objective of the project is to evaluate if the topical administration of Fluoresceinisothiocyanate (FITC)-Adalimumab during the endomicroscopic examination of the gut in Crohn's disease (CD) patients shows an acceptable safety profile. Another objective is to explore whether the use of FITC-Adalimumab as a predictive biomarker might reliably predict patient response to Adalimumab therapy and hence enable optimized utilization of this treatment option.

Inclusion Criteria:

Trial subjects must meet all of the following inclusion criteria:

• Male and female subjects from 18 to 70 years of age who are capable of giving informed consent without any restrictions
• Endoscopically and histologically confirmed diagnosis of Crohn's disease (CD)
• Manifestation of CD in the colon and/or in the terminal ileum
• Currently active CD with a CDAI score >150
• Clinically inadequate response of CD to systemic glucocorticoids and/or immunosuppressants (azathioprine, 6-mercaptopurine, methotrexate) or glucocorticoid-dependent CD or any contraindication to glucocorticoids
• Indication for treatment with Adalimumab
• Indication for intestinal confocal laser endomicroscopy prior to institution of adalimumab therapy
• Subject is mentally capable of understanding the nature and purpose/conduct of the clinical trial and of following the study staff's instructions
• Subject has given written informed consent after being informed by an investigator

Female subjects additionally must meet at least one of the following criteria:

• Must be menopausal (at least 12 months' natural amenorrhea or 6 months' amenorrhea with serum FSH >40 mU/mL) or
• Must have undergone bilateral oophorectomy or hysterectomy or
• Must be a regular, correct, and reliable user of a contraceptive method with a failure rate of <1% per year (such as oral contraceptives, implants, depot shots, intrauterine device, hormone coil)
• Must have a vasectomized partner

Exclusion Criteria:

• Subjects must not meet any of the following exclusion criteria:
• Impaired blood clotting (prothrombin rate <50% and/or PTT >55 sec and/or a platelet count of <50,000/μL)
• Pregnancy and lactation

Contraindications to treatment with adalimumab:

• Moderate to severe heart failure (NYHA Class III/IV)

• Active tuberculosis

• Severe acute infections, e.g. sepsis

• Opportunistic infections including invasive fungal infections

  • Known hypersensitivity to any of the ingredients of the study product or to any drug with a similar chemical structure
  • Treatment with beta-receptor blocking agents (because of altered symptoms in case of possible anaphylactic reactions to IV fluorescein)
  • Any other condition or medical treatment that, in the investigator's judgment, is not compatible with participation in the trial
  • Individuals who are in a relationship of dependence on or employed by the sponsor or any of the investigators
  • Planned prolonged stay outside the region of the study site, preventing the subject from returning for scheduled visits
  • Participation in any other clinical trial or administration of any investigational drug within the last four weeks prior to the screening visit