Safety of Rituximab biosimilar (Riximyo®) following a single switch from the reference product in patients with Non-Hodgkin's lymphoma: a retrospective study.

Unlike small molecule drugs and generic products, the active component of biologics and biosimilars are not identical chemical entities. Despite bioequivalence, there is limited evidence in clinical practice (i.e. Phase IV post-marketing surveillance) regarding the safety of biosimilar rituximab and even less so for "switching therapy" with respect to safety. Drug substitution by switching aims to realise cost savings by changing therapy involving a reference (biologic) product to a biosimilar. A retrospective analysis of safety outcomes including treatment-emergent adverse effects (TEAEs), rates of death and discontinuation of therapy, for all patients that received switching therapy (from reference to biosimilar rituximab, n = 33) was compared to patients who did not did not switch therapy (received biosimilar rituximab only, n = 18) at an Australian metropolitan cancer centre, over a six-month period. There was no statistical significant differences for any safety outcomes examined. Switching therapy for patients receiving rituximab does not lead to poorer safety outcomes.