Switching between intravenous and subcutaneous trastuzumab: Safety results from the PrefHer trial

AIM: To assess the safety and tolerability of switching between subcutaneous (SC) and intravenous (IV) trastuzumab in the PrefHer study (NCT01401166). PATIENTS AND METHODS: Patients with HER2-positive early breast cancer completed (neo)adjuvant chemotherapy and were randomised to receive four cycles of SC trastuzumab, via single-use injection device (SID; Cohort 1) or hand-held syringe (Cohort 2), followed by four cycles of IV, or vice versa (the crossover period presented here) as part of their 18 standard cycles of adjuvant trastuzumab treatment. Adverse events (AEs) were reported using standard criteria. RESULTS: Overall, fewer AEs were reported during the IV treatment periods, regardless of administration sequence (IV→SC or SC→IV). Differences in AEs between the SC and IV periods were partly due to variances in grade 1 and 2 local injection site reactions (ISRs) and systemic administration-related reactions (ARRs) and these occurred mainly during SC treatment, as expected. When ISRs and ARRs were excluded, rates of AEs were higher during the first treatment period, compared with the second, in both treatment sequences; otherwise there was no clear pattern in the type of AEs reported. Rates of clinically important events, including grade ≥3 AEs, serious AEs, AEs leading to study drug discontinuation and cardiac AEs, were low and similar between treatment arms (<5%). There were no grade 4 or 5 AEs. No new safety signals for trastuzumab were observed. CONCLUSIONS: PrefHer revealed that switching from IV to SC trastuzumab (hand-held syringe or SID) or vice versa did not impact the known safety profile of trastuzumab.