P705 Switching from intravenous to subcutaneous infliximab: clinical and patient experience outcomes

Abstract

Background Intravenous (IV) infliximab (IFX) monotherapy is associated with significant loss of response. Therapeutic drug monitoring shows an association with low serum trough drug levels and development of anti-IFX antibodies. Combination therapy with immunomodulators is not always possible, and IFX dose escalation leads to higher drug costs and time pressure on infusion units. Both approaches have raised heightened patient safety concerns due to the Covid-19 pandemic. Subcutaneous (SC) IFX pharmacokinetics lead to improved drug trough levels, which could lead to better clinical outcomes. Methods The NHS Greater Glasgow and Clyde biologics database was used to identify selected patients currently treated with IV IFX for IBD for suitability for SC switch. Patients were contacted to allow informed choice to opt in or out of switch. Baseline clinical data was collected, and patients were reviewed at week 8 and week 24 for assessment of clinical disease activity scores, IFX trough levels/anti-drug antibody levels, and faecal calprotectin. Patient experience outcomes were assessed using a quality of life questionnaire (CUCQ-8). Results 31 patients consented to switch; F:M = 17:14. The majority of patients (16) had Crohn’s disease, with 13 with UC and 2 IBDU. Mean duration of disease was 9.1 years and duration of prior IV therapy was 3.3 years. 28 patients were reviewed at week 8 and 24 at week 24. At week 24, 71% of patients were in clinical remission (Harvey-Bradshaw index score <5 or partial Mayo score <2), 96% had CRP <5 mg/Land 87% had FCP <250µg/g. 21% of patients had subtherapeutic IFX trough levels at baseline, all had increased by week 8 and there were no subtherapeutic levels measured by week 24. One patient had detectable antibodies at week 24, compared with 9 patients at baseline. Three patients required oral steroid therapy during the 24-week follow up period. There were no hospital admissions, significant infections or adverse reactions within the cohort. 15 patients submitted CUCQ-8 scores, of these 7 patients’ scores had worsened at week 8 but by week 24 13/15 were stable or improved compared to baseline. Conclusion Switching from IV to SC infliximab is welcomed by most patients. The efficacy, tolerability, increased drug level and safety which has previously been demonstrated is reproduced in our cohort. This study is the first to explore patient experience outcomes. The finding of initial worsening of the CUCQ-8 score, but overall improvement by week 24 opens further opportunity for engaging patient involvement in switch programmes.