OBJECTIVES: In the UK, biosimilar rituximab and trastuzumab have lower prices than originators but are available only in intravenous (IV) formulations. We assessed the budget impact of adopting IV biosimilar rituximab and IV biosimilar trastuzumab compared with subcutaneous (SC) and IV originators from the perspective of the UK National Health Service (NHS).

METHODS: Patients were included if they had received rituximab for rheumatoid arthritis, chronic lymphocytic leukaemia, Non-Hodgkin’s lymphoma (NHL), granulomatosis with polyangiitis and microscopic polyangiitis (MPA), and trastuzumab for early breast cancer, metastatic breast cancer and metastatic gastric cancer. Drug acquisition and administration costs were obtained from national tariffs. Projected biosimilar uptake ranged from 19–90% over five years.

RESULTS: Compared with sc originators, administration costs for IV biosimilars were higher but drug costs were reduced, leading to lower total cost for IV biosimilars. Per-patient savings with IV biosimilar rituximab ranged from £328 (MPA) to £774 (NHL). Per-patient savings with IV biosimilar trastuzumab ranged from £4,623 (gastric) to £4,824 (breast). At maximum uptake, 76% of patients switched to biosimilar rituximab, resulting in annual savings of £8.2m. If 67% of patients switched to biosimilar trastuzumab, the annual saving was £49.2m. The larger saving with trastuzumab was due to higher originator price and greater cost difference between originator and biosimilar. Scenario analysis found cost savings to be sensitive to IV biosimilar price but not sensitive to plausible variation in administration costs. Further scenario analysis estimated a positive budget impact for a hospital provider, with increased reimbursement revenue outweighing additional IV administration costs.

CONCLUSIONS: Increasing biosimilar rituximab and trastuzumab uptake can deliver substantial cost savings for the NHS. Increased administration cost should not act as a barrier to IV biosimilar uptake. The ability to realise these benefits will depend on price agreed and capacity to deliver larger numbers of IV infusions.