Trastuzumab/Hyaluronidase-oysk: A New Option for Patients With HER2-Positive Breast Cancer

Objective: To assess the use of subcutaneous trastuzumab/hyaluronidase-oysk (SQ trastuzumab) in comparison to intravenous (IV) trastuzumab. Data Sources: A comprehensive PubMed literature search was performed from August 2012 to August 2019 using search terms Herceptin Hylecta, trastuzumab, hyaluronidase, subcutaneous, preference, safety, efficacy, and cost. Study Selection & Data Extraction: English-language clinical trials focusing on SQ trastuzumab were evaluated. Data Synthesis: In phase III trials, adverse event (AE) rates ranged from 64% to 97.6% of patients receiving SQ trastuzumab in 3 studies compared to 94.6% of patients receiving IV trastuzumab. In the phase III trial comparing SQ trastuzumab to IV trastuzumab, six-year overall survival (OS) was 84% in both groups. In pharmacokinetic analyses, trough concentrations and AUC0-21 were slightly higher in patients receiving SQ trastuzumab and differences were larger at the extremes of body weight. Two pharmacoeconomic analyses reported cost-savings associated with a 52-week treatment cycle of trastuzumab of $2,090 USD and $4,600 USD. Relevance to Patient Care and Clinical Practice: Food and Drug Administration (FDA)-approved in February 2019, SQ trastuzumab, a monoclonal antibody that binds to human epidermal growth factor receptor 2 (HER2) protein in combination with hyaluronidase, offers an alternative dosage form for patients with breast tumors overexpressing HER2. Conclusions: SQ trastuzumab has a similar safety profile to IV trastuzumab. Although it may be slightly more cost-effective, its role in the treatment of HER2-overexpressing tumors requires further study in those at the extremes of body weight due to differences in drug exposure compared to IV trastuzumab.