Abstract GS3-04: A randomized phase III study of adjuvant trastuzumab for a duration of 9 weeks versus 1 year, combined with adjuvant taxane-anthracycline chemotherapy, for early HER2-positive breast cancer (the SOLD study)

Background: The optimal duration of trastuzumab (T), when given together with chemotherapy and after chemotherapy as adjuvant treatment in patients with HER2+ breast cancer (BC), is unknown. Whilst the international standard is 12 months of T, the benefits and harms of T treatment continued beyond the chemotherapy are unclear. Methods: Women with histologically confirmed node-negative or node-positive HER2+ BC were eligible for the trial (NCT00593697). The primary tumor diameter was required to be u003e5 mm in node-negative cancer. Patients with distant metastases, inflammatory cancer, clinically significant cardiac disease, left ventricular ejection fraction (LVEF) 1, and those who had received neoadjuvant systemic cancer therapy were excluded. Patients were randomly assigned to 2 groups prior to starting systemic cancer therapy. The initial systemic treatment was identical in the groups consisting of 3 cycles of 3-weekly docetaxel plus T followed by 3 cycles of fluorouracil, epirubicin, and cyclophosphamide (FE75C). Thereafter, no further T or chemotherapy was administered in Arm A, whereas in Arm B single-agent T was administered 3-weekly for 14 cycles to complete 1 year of T treatment. The docetaxel dose was either 80 mg/m2 or 100 mg/m2 (prespecified for each center). Radiation therapy and endocrine therapy (for patients with ER+ cancer) were given according to the institutional practice; the minimum scheduled duration of endocrine therapy was 5 years. The LVEF was measured pretreatment, and on study weeks 18, 31, 43, and 61 and month 36. The primary endpoint was disease-free survival (DFS) compared between the groups using a Cox model and the non-inferiority approach. Results: A total of 2,176 patients were entered into the study from 63 centers in 7 countries from Jan. 3, 2008 to Dec.16, 2014. The median follow-up time was 5.2 years at data collection closure (Dec. 31, 2016). The efficacy and safety data will be presented at the meeting. Citation Format: Joensuu H, Fraser J, Wildiers H, Huovinen R, Auvinen P, Utriainen M, Nyandoto P, Villman KK, Halonen P, Granstam-Bjorneklett H, Lundgren L, Yachnin J, Turpeenniemi-Hujanen T, Ritchie D, Huttunen T, Neven P, Canney P, Harvey VJ, Kellokumpu-Lehtinen P-L, Lindman H. A randomized phase III study of adjuvant trastuzumab for a duration of 9 weeks versus 1 year, combined with adjuvant taxane-anthracycline chemotherapy, for early HER2-positive breast cancer (the SOLD study) [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS3-04.