RT Journal Article SR Electronic T1 Safety and tolerability of subcutaneous trastuzumab and intravenous pertuzumab as adjuvant treatment for HER2 positive breast cancer: a pilot study JF Postgraduate Medical Journal JO Postgrad Med J FD The Fellowship of Postgraduate Medicine SP postgradmedj-2021-140319 DO 10.1136/postgradmedj-2021-140319 A1 Wong, Chi Yan A1 Leung, Roland A1 Kwok, Gin Wai A1 Tsang, Josephine A1 Li, Bryan A1 Yau, Thomas A1 Chiu, Joanne YR 2021 UL http://pmj.bmj.com/content/early/2021/05/26/postgradmedj-2021-140319.abstract AB Background Subcutaneous (SC) trastuzumab is similar to intravenous trastuzumab in terms of pharmacokinetics, efficacy and tolerability. The use of dual anti-HER2 agents trastuzumab and pertuzumab has become the new standard for node-positive HER2-positive breast cancers at adjuvant setting, but the safety and tolerability of combining SC trastuzumab and intravenous pertuzumab is not well studied.Methods This was a prospective single-arm pilot study with locally advanced HER2-positive breast cancer who received adjuvant SC trastuzumab and intravenous pertuzumab after standard anti-HER2 treatment with chemotherapy. Primary outcomes included adverse events (AEs), severe AEs and cardiac AEs. Secondary outcome was invasive disease-free survival (iDFS).Results With a median follow-up of 21.7 months, 20 patients were enrolled. One patient (5%) developed asymptomatic drop in left ventricular ejection fraction from 69% to 53%. Two patients (10%) developed grade 1 injection site reaction related to SC trastuzumab. There were no grade 2 or above AEs. All AEs were transient. No new AEs were observed. The 1-year iDFS was 90% (95% CI 0.656 to 0.974)Conclusions Combination of SC trastuzumab and intravenous pertuzumab for HER2-positive breast cancer is a safe and well-tolerated option in adjuvant setting.All data relevant to the study are included in the article or uploaded as supplementary information. The authors confirm that the data supporting the findings of this study are available within the article.