Authors: Rachel Wuerstlein, Paul Ellis, Filippo Montemurro, Antonio Antón Torres, Suzette Delaloge, Qingyuan Zhang, Xiaojia Wang, Shusen Wang, Shao Zhimin, Huiping Li, Andhika Rachman, Mawin Vongsaisuwon, Haiying Liu, Simon Fear, Claudia Pena-Murillo, Carlos H. Barrios
Published: 2021-06-02
DOI: 10.1200/jco.2021.39.15_suppl.1039
Source: Full article
1039 Background: KAMILLA is an open-label, single-arm, phase 3b safety study of T-DM1 in pts with HER2-positive advanced BC (NCT01702571). The treated (safety) population of KAMILLA comprises 2 cohorts: a larger global Cohort 1 (n=2002) and a smaller Asia Cohort 2 (n=181 [China, n=154; Thailand, n=15; Indonesia, n=12]). Here we report results from Cohort 2 in the context of those previously reported for Cohort 1. Methods: Pts had HER2-positive, locally advanced or mBC with progression after chemotherapy and anti-HER2 therapy or ≤6 months (mo) of completing adjuvant therapy. T-DM1 3.6 mg/kg was given intravenously every 3 weeks until disease progression, consent withdrawal, or unacceptable toxicity. Primary endpoints were grade ≥3 (G≥3) adverse events of primary interest (AEPIs), specifically hepatic events, allergic reactions, thrombocytopenia (TCP), and hemorrhage events; all other G≥3 treatment-related AEs (TRAEs); and all-grade pneumonitis. Results: As of 31 July 2019,KAMILLA enrolled 2185 pts (Cohort 1, n=2003; Cohort 2, n=182), of which 2002 and 181 in each cohort, respectively, received ≥1 study dose and were included in the safety population. Baseline characteristics were generally similar between cohorts. Median (range) T-DM1 exposure was 5.6 mo (0–46) for Cohort 1 and 5.0 mo (0–31) for Cohort 2. The overall G≥3 AEPI rate was higher in Cohort 2 vs Cohort 1 (Table), mostly driven by a higher G≥3 TCP rate in Cohort 2. In Cohort 2, G≥3 TCP (the most frequently reported G≥3 AEPI) did not appear to be associated with G≥3 hemorrhagic events — the majority of G≥3 TCP events (128/138) fully resolved, with a duration of ≤15 days for 98/138 of these events. G≥3 TRAE rates were 18.4% in Cohort 1 and 48.6% in Cohort 2, the latter mainly due to TCP and platelet count decreased; any-grade pneumonitis rates were 1.0% and 2.2%, respectively. No other safety signals were identified. Median progression-free survival and overall survival were similar for both cohorts (Table). Conclusions: These data confirm prior observations in an Asian subgroup of the phase 3 EMILIA trial of T-DM1 in pts with previously treated mBC. Although the G≥3 TCP rate was higher in the Asia cohort, the majority of these events resolved fully. OS and PFS were similar in both cohorts. These data reinforce the favorable T-DM1 benefit-risk profile in mBC. Clinical trial information: NCT01702571 .[Table: see text]