Background: Standard of care for HER2+ early/first-line metastatic BC (EBC/MBC) is P + H and concurrent chemotherapy (CT); PH FDC SC offers faster, more convenient admin vs intravenous (IV) P + H. COVID-19 has caused unprecedented strain on healthcare systems and disruption to cancer care; treatment (Tx) at home may: enable pts to continue cancer Tx; reduce exposure to COVID-19; free up hospital resources. This study’s main objectives: to enable continuity of care during COVID-19; to assess safety of PH FDC SC given at home. Methods: This is an ongoing single-arm, hybrid, decentralized clinical trial (NCT04395508). Pts with HER2+ EBC/MBC who completed concurrent CT with P + H IV and are receiving/about to receive maintenance P + H IV, PH FDC SC, or H SC are switched to PH FDC SC given at home by a home health nursing provider (HHNP) until disease progression, unacceptable toxicity, pt withdrawal, or physician recommendation (pts with EBC will complete ≤18 cycles). The study endpoint is safety. A subset of pts took part in HARRIET, a substudy of at-home cardiac surveillance with artificial intelligence-guided cardiac ultrasound and optional 6L ECG acquired by an HHNP. Results: Data for 114 pts (1 male) were available at cutoff (Jan 19, 2022): 18 (16%) completed Tx; 20 (18%) discontinued; 76 (67%) remain on study; 79 (69%) had a COVID-19 vaccine while on study. Median age was 49 years; pts were balanced between EBC (n = 55, 48%) and MBC (n = 59, 52%); received a median of 6 (EBC) and 8 (MBC) cycles; and were from metropolitan (n = 109), urban (n = 4), and rural (n = 1) areas. 11 pts tested COVID-19-positive during the Tx phase: 8 continued Tx after appropriate COVID-19 Tx and/or quarantine. Safety is summarized in the table. No new adverse events (AEs) emerged due to home admin. AEs of special interest were grade (gr) 1–2: admin-related reactions (n = 76, 67%), hypersensitivity (n = 5, 4%), cardiac dysfunction (n = 4, 4%), except 1 case of gr ≥3 diarrhea. AEs leading to study Tx discontinuation or interruption/dose reduction occurred in 3 (3%) and 15 (13%) pts. A subset of 7 pts completed at-home cardiac surveillance testing; quantitative assessment of left ventricular ejection fraction was feasible in 3 (43%); 5 (71%) preferred at-home surveillance to clinic. Conclusions: In this preliminary analysis, safety of PH FDC SC at home was consistent with the established P + H safety profile, indicating that PH FDC SC at home is a viable option for continuing BC care during and beyond COVID-19. Clinical trial information: NCT04395508.

*Not Tx-related: COVID-19 pneumonia, cystitis, acute kidney injury, diarrhea, seizure, sepsis, transient ischemic attack (gr 2).