Abstract PD3-10: Safety results from a randomized, double-blind, phase 3 study of ABP 980 compared with trastuzumab in patients with breast cancer

• Published in: Cancer research (Chicago, Ill.) Ill.), 2018-02, Vol.78 (4_Supplement), p.PD3-10-PD3-10
• Main Authors: Kolberg, H-C, Demetriou, GS, Zhang, N, Tomasevic, Z, Hanes, V
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS17-PD3-10

Background: Analytical, functional, and pharmacokinetic similarity between the proposed biosimilar ABP 980 and trastuzumab (TRAS) has been shown. Similar efficacy and safety have also been demonstrated in the neoadjuvant phase of the phase 3 comparative clinical study. Here we focus on the safety and immunogenicity results from the adjuvant phase of this study. Methods: The objective of this study was to compare ABP 980 with TRAS in women with HER2 positive early breast cancer. After run-in anthracycline-based chemotherapy, patients were randomized 1:1 to intravenous ABP 980 or TRAS plus paclitaxel Q3W for 4 cycles. Surgery was completed 3-7 weeks after the last dose of neoadjuvant study drug. After surgery, patients who initially received TRAS were allocated to either continue TRAS (TRAS/TRAS arm) or undergo a single switch to receive ABP 980 (TRAS/980 arm) and patient who initially received ABP 980 continued to receive ABP 980 (980/980 arm) Q3W for up to 1 year. This report is based on safety data collected at the time of primary analysis, when all patients had completed the first post-surgery clinical visit or had withdrawn. The majority of patients had completed the study at the time of this analysis. Results: 725 patients were randomized; 364 and 361 patients were randomized to ABP 980 and TRAS, respectively, in the neoadjuvant phase. Following surgery, 349 patients in the 980/980 arm, 171 patients in the TRAS/TRAS arm, and 171 patients in the TRAS/980 arm entered the adjuvant phase. Adverse events (AEs) during the adjuvant phase are shown in Table 1; data from the neoadjuvant safety phase have been previously reported. Table 1 980/980 (N = 349)TRAS/TRAS (N = 171)TRAS/980 (N = 171)AE category, n (%)   Any AE201 (57.6)89 (52.0)98 (57.3)Any grade ≥3 AE27 (7.7)10 (5.8)10 (5.8)Any fatal AE001 (0.6)Any serious AE14 (4.0)4 (2.3)4 (2.3)AEs of Interest, n (%)   Infections and infestations46 (13.2)14 (8.2)21 (12.3)Neutropenia37 (10.6)16 (9.4)13 (7.6)Infusion reactions27 (7.7)10 (5.8)15 (8.8)Hypersensitivity11 (3.2)3 (1.8)7 (4.1)Pulmonary toxicity3 (0.9)2 (1.2)1 (0.6)Cardiac failure01 (0.6)1 (0.6)LVEF decline by ≥10% and to below 50%, n/N* (%)9/313 (2.9)3/154 (1.9)3/153 (2.0)LVEF = left ventricular ejection fraction; N* = Number of patients with data available One patient in the TRAS/980 arm developed binding antibodies during the adjuvant phase; this patient tested negative for neutralizing antibodies. In the neoadjuvant phase, 2 patients in the ABP 980 arm an