Daniel Argolo, Marissa Friedman, Neil Iyengar, Sujata Patil, Larry Norton, Jose Baselga, Clifford Hudis, Chau Dang
Institution: MSKCC, New York, NY; CLION-GRUPO CAM, Salvador, BA
Background/Objectives: Dual anti-HER2 blockade with trastuzumab and pertuzumab (HP) plus chemotherapy is an effective therapy (Rx) in the 1st-line setting for HER2-positive metastatic breast cancer (MBC). Our single arm phase II study included patients (pts) treated with HP plus paclitaxel in the 2nd-line setting with progression-free survival (PFS) benefit. Recently, we reported results from a retrospective study of pts treated at our institution, suggesting a longer PFS for those who received HP-based Rxs when compared to any other anti-HER2 based Rxs in the 2nd-line setting. To further assess the activity of this combination in later Rx lines, we conducted a retrospective analysis of pts with HER2-positive MBC who had progressive disease after 2nd-line and were treated with HP-based Rxs in the 3rd and later lines at MSKCC. Historically, the median (med) PFS in this setting with trastuzumab-based Rx is about 3-4 months. Methods: Pts diagnosed with HER2-positive MBC and treated with HP-based Rxs at MSKCC between 1-1-2011 and 03-30-2015 and who progressed on 2nd-line Rx were identified through an institutional database. Primary endpoint was PFS in 3rd and later treatment lines. Results: Seventy pts who received any HP-based Rx in the 3rd or later lines of treatment were eligible. The med number of prior anti-HER2 Rx was 3. The med PFS for the entire cohort was 5.7 months (95% CI, 5.2-7.1). Conclusion: In this retrospective analysis involving heavily pretreated patients, HP-based Rx appears to be an active regimen and compares favorably to historical data. This supports the NCCN endorsement of HP-based Rx in later lines if HP has not been delivered previously. Keywords: metastatic breast cancer, HER2, dual blockade, trastuzumab, pertuzumab.ND LATER LINE OF TREATMENT FOR HER2-POSITIVE METASTATIC BREAST CANCER: A RETROSPECTIVE STUDY FROM A SINGLE INSTITUTION