Metronomic chemotherapy (MC): Results of two feasibility trials in patients (pts) with HER2 positive (HER2+) and negative (HER2-) locally advanced breast cancer (LABC).

Abstract

e11513 Background: In SWOG0012, MC improved pathologic complete response (pCR) compared to standard neoadjuvant chemotherapy (NC). We evaluated the feasibility of MC with a taxane→anthracycline schedule, which has also been shown potentially superior to the inverse sequence. We also evaluated the feasibility of MC in combination with trastuzumab. Methods: The primary objective was feasibility (defined as a febrile neutropenia (FN) rate ≤10%). Secondary objectives were cardiac safety, tolerability and efficacy as measured by objective response and pCR. The original accrual goal was 25 Her2+ pts and 40 Her2- pts. Her2- pts received paclitaxel (100mg/m2) x8 weeks followed by doxorubicin (24mg/m2) x9 weeks combined with oral cyclophosphamide (100mg/day), without G-CSF. Her2+ pts also received weekly trastuzumab (4 mg/kg followed by 2mg/kg) concurrently with the entire CT. Results: Most pts were stage III (Her+: 8/9; Her-: 4/11). The Her2+ cohort was prematurely closed after 2(22%) pts developed G3 pneumonitis (both during the MC phase). Both recovered completely. There was 1 case of asymptomatic LVEF drop to below 50% (during the taxane phase); 1 pt had G2 hand-foot skin reaction (HFS) and another had G2 mucositis. The Her2- cohort was also prematurely closed with only 11 pts due to high rates of mucocutaneous toxicity (G3 HFS in 36%, G3 rash in 9%) and also because of SWOG0221 negative results. There were 2(18%) cases of FN, but no cases of pneumonitis. 1/11(9%) Her2- and 5/9(55%) Her2 + pts had a pCR. VEGF-related biomarkers were collected and will be presented at a later date. Conclusions: The proposed MC schedules proved too toxic to be considered for further clinical development. In addition, MC resulted in unexpectedly high rates of severe pulmonary toxicity when given in combination with trastuzumab. Her2+ but not Her2- pts had an impressively high pCR rate.