GAIN-2: Neo-/adjuvant phase III trial to compare intense dose-dense chemotherapy (CT) to tailored dose-dense CT in patients (pts) with high risk early breast cancer (EBC): Results on safety and interim invasive disease-free survival (iDFS).

Abstract

516 Background: GAIN-2 (NCT01690702) compared efficacy and safety of intense, dose-dense epirubicin, nab-paclitaxel, and cyclophosphamide (iddEnPC) vs dose-dense, dose-tailored epirubicin/ cyclophosphamide followed by dose-dense, dose-tailored docetaxel (dtEC-dtD) as adjuvant or neoadjuvant CT for node-positive or high risk node-negative EBC. Here, we report safety results and interim analysis (IA) of the primary endpoint iDFS. Methods: Pts (luminal A ≥N2; luminal B N+; HER2+ and TNBC) were randomized between iddEnPC (E 150 mg/m2, nP 330 mg/m2, C 2000 mg/m2, all q2w x 3) or dtEC-dtD (dtEC q2w x 4 followed after 1 week rest by dtD q2w x 4). Primary objective was to compare iDFS. 797 events are needed to detect a hazard ratio of 0.819 with a 2-sided log-rank-test with 80% power and α=0.05. The IA of iDFS was planned after 50% of the events have occurred. Safety and compliance were secondary objectives. Results: Between 10/2012 and 09/2018, 2887 pts were randomized and 2857 started treatment (iddEnPC 1429; dtEC-dtD 1428). Median age was 51 (range 18-75) years. Overall, 18.1% were luminal A, 31.5% luminal B/HER2-, 18.8% hormone-receptor (HR)+/HER2+, 8.5% HR-/HER2+ and 23.2% TNBC. Overall, 88.1% of pts completed all treatment in both arms. 66.8% with iddEnPC vs 58.8% with dtEC-dtD delayed CT dose (p<0.001). Grade 3-4 non-hematological adverse events (AEs) were more frequent with iddEnPC (iddEnPC 50.8% vs dtEC-dtD 45.1%, p=0.002). Grade 3-4 leukopenia, neutropenia, febrile neutropenia, arthralgia, and peripheral sensory neuropathy were significantly higher with iddEnPC. There were 1464 serious AEs (iddEnPC 870 vs dtEC-dtD 594) and 26 (9 vs 17) predefined AEs of special interest (anaphylaxis, any AE affecting cranial nerves, macula edema). Two deaths occurred during dtEC-dtD. After a median follow-up of 45.8 months, there was no difference in iDFS between arms (log-rank p=0.9102, hazard ratio iddEnPC vs dtEC-dtD 1.01, 95% CI 0.83-1.23). Conclusions: No new safety concerns were observed. Use of both iddEnPC and dtEC-dtD appears feasible in the (neo)adjuvant treatment of high risk EBC. Clinical trial information: NCT01690702 .