PO62 FIRST LINE TRASTUZUMAB-BASED THERAPY IN HER2-POSITIVE METASTATIC BREAST CANCER PATIENTS PRESENTING WITH DE NOVO OR RECURRENT DISEASE: A MULTICENTER RETROSPECTIVE COHORT STUDY

Abstract

s / The Breast 24 S3 (2015) S21–S75 S43 this setting. In order to improve pts’ comfort using the oral form of V, we conducted a multicenter phase II study to investigate efficacy and safety of the oral V-T (OVT) combination. Methods: Main eligibility criteria: HER-2Neu positive disease (3+ IHC or FISH+), no adjuvant CT within the last 6 months and no prior CT for MBC. Pts were treated with oral V (oV) 80 mg/m2 D1, D8, D15 (following first 3 administrations at 60 mg/m2 during the first cycle) for a total of 8 cycles (1 cycle = 3 weeks); in combination with (T) 6 mg/ kg on D1 (loading dose, 8 mg/kg) every 3 weeks or 4 mg/kg (loading dose, 6 mg/kg) weekly. Continuation and schedule of (T) were at investigator’s discretion. Response was evaluated every 2 cycles using RECIST 1.0.Primary endpoint: Objective response rate (ORR); secondary EPs: Duration of response (DOR), progression free survival (PFS), overall survival (OS), safety. Results: In the full population (n=26), median age was 50.7 years (range 31.3-80.7); median WHO PS 0 (range 0-1). 69% of pts were postmenopausal and 65% took prior (neo)adjuvant CT. Early stage treatment consisted of a combination of anthracyclines (AC) and taxanes (TX) in 27% of pts. Overall 46% of the pts were pretreated by AC, 38.5% by TX. Median disease free interval was 50.7 (95% CI [43.6-57.9]) months (m). Most frequent metastatic sites were bone (61.5%), liver (50%) and lymph nodes (42%). 73% of pts had 2 or more metastatic sites. A median of 8 oVT cycles were given (range: 3-12): 19% of oV doses were not escalated to 80mg/m2 starting cycle 2. 92% of pts administered T every 3 weeks. In the evaluable pts population, ORR was 56% (95% CI [34.9-75.6]), including 3 complete responses (12%) and 11 partial (44%), 8 pts (32%) had stable disease resulting in a clinical benefit [or disease control] rate of 88 % (95% CI [68.8-97.5]). Median DOR was 7.1m (95% CI [3.9-10.2]). At the time of the analysis, median PFS was 6.7m (95% CI [3.5-10]) and median OS 27.9m (95% CI [17.4-38.3]). Treatment was generally well tolerated with main observed grade 3-4 hematological toxicities being neutropenia (46%) and anemia (4%). Grade 3-4 nausea-vomiting were observed in 11.5% of pts. Conclusion: Our results confirm the efficacy of OVT combination as a first line treatment in Her2 Neu+ LA or MBC pts with an acceptable safety profile. OVT optimizes the convenience of this CT regimen, especially for the pts receiving T every 3 weeks.