P013 Resolution of Infliximab Associated Infusion Hypersensitivity After Switching to Biosimilar Infliximab-dyyb

CASE: Background: Administration of infliximab for the treatment of inflammatory bowel disease has a well-recognized risk of infusion-related (IR) adverse events. The recent introduction of the biosimilar infliximab-dyyb (Inflectra®) has been shown to have similar efficacy with comparable safety profile when compared to infliximab; however, although the active ingredients are similar, the inactive ingredients are different. We present a case of a 26-year-old female with ulcerative colitis who had resolution of her IR hypersensitivity when switched from infliximab to infliximab-dyyb. CASE DESCRIPTION: A 26-year-old female with a past medical history of ulcerative pancolitis presented to our clinic with the chief complaint of rash associated with her infliximab infusions. She described pruritic raised lesions which would occur on her upper and lower extremities during her infusions. She denied any shortness of breath or wheezing, and her symptoms were well controlled with methylprednisolone 40mg IV prior to her infusions. Previously, she had been treated for her UC with oral mesalamine, azathioprine and intermittent prednisone and did not have any adverse reactions to these medications. She has no known allergies to other medications and her peripheral eosinophil count was 1.6%. She was initially started on infliximab 5mg/kg every 8 weeks since 2013 and had achieved clinical as well as endoscopic remission with her most recent colonoscopy graded as Mayo 0. On account of her infusion reaction, drug antibodies were checked but were not detected. Infliximab level was 8.8 μg/ml. Due to insurance she was required to switch to infliximab-dyyb. After switching to the biosimilar, she has not had any infusion related reactions and no longer requires premedication with methylprednisolone with her infusions. DISCUSSION: Immediate IR reactions have been reported in 5-23% of IBD patients receiving infliximab and those who develop antibodies towards infliximab have a 2-fold risk of acute IR events. Side effects have been reported to be the primary reason for discontinuation of infliximab, and studies have shown that discontinuation can lead to an increased risk of relapse of inflammatory bowel disease. Although infliximab and infliximab-dyyb have analogous active ingredients, the inactive ingredients differ. Specifically, infliximab-dyyb lacks monobasic sodium phosphate and dibasic sodium phosphate, which acts as an emulsifier which we believe contributed to her IR with originator biologic infliximab. It is important to recognize these differences as IR hypersensitivities may be attributed to inactive ingredients; especially when antibodies are negative. Our case report suggests that a switch to biosimilar infliximab in patients may provide added benefit especially in those that have reactions occurring from inactive ingredients in the originator biologic.