Golimumab Dried Blood Spot Analysis

This retrospective multi-centric Belgian prospective trial will involve 10 patients initiating or under maintenance subcutaneous golimumab therapy for moderate-to-severe colitis at the University Hospitals Leuven (Leuven, Belgium) or AZ Groeninge (Kortrijk, Belgium)

Patients will (have) receive(d) standard induction therapy with golimumab 200mg at week 0, and golimumab 100mg at week 2. Maintenance therapy will (have) start(ed) at week 6, with 50 or 100mg of golimumab every 4 weeks, depending on body weight (50mg every 4 weeks for patients with a body weight of less than 80kg, and 100mg for the others)

Patients will come to the hospital for clinical evaluation, blood sampling and golimumab administration following daily clinical practice. The patients will be requested to perform several dry blood spot analyses at home.

BLOOD SAMPLING:

Blood samples are collected using two sampling methods at different time points (indicated on the timeline above); DBS sampling (max 39 samples/patient) and venous blood sampling (max 13 samples/patient). Venous blood sampling will be performed during a standard outpatient clinic in one of the participating centres, and forwarded to the Laboratory for Therapeutic and Diagnostic Antibodies in Leuven for further analyses. DBS samples will be send directly to the Laboratory for Therapeutic and Diagnostic Antibodies in Leuven through classical mailing.

DBS sampling will be performed by the patient during the outpatient clinic (at same moment as venous punctures, max 13 samples/patient) and at home for the intermediate values (max 26 samples/patient). Patients will be taught how to perform a finger prick during the outpatient clinic. A conversion factor will be defined. Determination of concentration-time profile and exposure of golimumab in the individual patients will be performed by intensive sampling for 3 to 4.5 months. Time point of max concentration, intermediate concentration, and trough concentration will be determined in each patient.

Note: A similar procedure will be adopted to measure free anti-golimumab antibody concentrations on the DBS using a drug sensitive assay. Free anti-golimumab antibody concentrations will be measured when the serum golimumab concentration is below limit of quantification.

MEASUREMENT OF GOLIMUMAB AND ANTI-GOLIMUMAB ANTIBODY CONCENTRATIONS:

Golimumab concentrations will be measured using a sandwich type ELISA, in which golimumab is captured between an immobilized monoclonal antibody towards golimumab (MA-GLM) 171D8 and an added horseradish peroxidase (HRP)-labeled MA-GLM159B8. The assay was developed and validated, analytically (external and internal) and clinically, as described by Detrez et al. Golimumab concentrations will be measured on every sample.

Free anti-golimumab antibody concentrations will be measured using a drug sensitive assay. Total anti-golimumab antibody concentrations will be measured using a drug tolerant assay. Development and validation (analytical + clinical) of these assays is described by Detrez et al. Total anti-golimumab antibody concentrations will be measured on every venous sample. Free anti-golimumab antibody concentrations will be measured when the serum golimumab concentration is below limit of quantification on both venous sample and DBS sample (based on adalimumab serum concentrations measured in by our laboratory, we expect that 11% of samples measured within the first year of treatment have an undetectable golimumab concentration).

BASELINE CHARACTERISTICS:

* Baseline characteristics will include: sex, age at diagnosis, weight, body mass index, disease extent, smoking status (never, ex, active), primary sclerosing cholangitis, haemoglobin, serum albumin, and C-reactive protein
* Previous medical characteristics will include previous use of mesalamine, steroids, immunosuppressive agents, ciclosporin, infliximab, adalimumab, vedolizumab, ...
* Current medical characteristics will include use of mesalamine, use of steroids (dosing, duration since initiation), use of immunosuppressive agents (dosing, duration since initiation), use of golimumab (dosing, duration since initiation, last dose), ...

QUESTIONNAIRE REGARDING PATIENT FRIENDLINESS:

• At the end of the study the participants will be requested to fill out a questionnaire regarding the patient friendliness of the dried blood spot (DBS) methodology

Eligibility Criteria:
Inclusion Criteria:

* Age at least 18 at moment of inclusion
* Established diagnosis of ulcerative colitis (UC)
* Patients under golimumab therapy for moderate-to-severe colitis, including minimally 3 patients who will initiate golimumab therapy

Exclusion Criteria:

* Subjects with Crohn's disease, or IBD type unclassified
* Subjects who underwent a subtotal colectomy or proctocolectomy