Switching to a Fixed-dose Combined Pertuzumab and Trastuzumab With Recombinant Human Hyaluronidase Subcutaneous Injection to Treat Human Epidermal Growth Factor Receptor 2-positive Breast Cancer in Real-world UK Clinical Practice.

Unlabelled: Current standard of care for human epidermal growth factor receptor 2 (HER2)-positive breast cancer is first-line treatment with chemotherapy in combination with the HER2-targeting monoclonal antibodies, trastuzumab and pertuzumab. While this treatment approach is associated with improved clinical outcomes, there is a treatment burden associated with the invasive and time-consuming nature of separate intravenous (IV) administration of pertuzumab and trastuzumab. In 2020, a novel subcutaneous (SC) formulation of pertuzumab plus trastuzumab with recombinant human hyaluronidase, available as a fixed-dose combination vial that can be administered in 5-8 minutes, was approved for use by the US Food and Drug Administration and the European Medicines Agency.

Aim: A UK cancer centre set out to switch all patients currently receiving IV infusion of pertuzumab and trastuzumab over to the combined SC injection in a safe and timely manner and to initiate all future patients on the combined SC injection.

Materials And Methods: Organisational governance approval was obtained before a novel project model approach was used to implement the treatment switch which incorporated aspects such as education and multidisciplinary team collaboration.

Results: Of the 97 eligible patients, 99% were switched to the combined SC injection safely and effectively over a 4-week period. Between 1st April 2021 and 30th September 2022, 3062 hours of pharmacy aseptic preparation time and 6764 hours of day unit chair time were saved. The number of aseptic unit operation days above the maximum capacity was reduced post-switch.

Conclusion: This initiative demonstrated the ability to rapidly and effectively transition >95% of eligible breast cancer patients from separate IV trastuzumab and pertuzumab to a fixed combined SC formulation. Patient benefits included shorter administration appointments and a less invasive form of treatment, whereas healthcare system benefits included substantial savings in aseptic preparation time and chair time, and a meaningful increase in clinic capacity. The reported treatment-switch process provides a model that can be adopted by other centres wishing to implement similar treatment switches.