Abstract P3-11-15: Patterns of Care and Outcomes of HER2 Positive Metastatic Breast Cancer Patients Receiving 3rd Line Therapy in an Outpatient Community Setting

Abstract

Abstract Introduction Treatment patterns and outcomes are not well known in later lines of therapy for patients (pts) with HER2+ metastatic breast cancer (MBC). The goal of this study was to evaluate commonly used regimens and outcomes in pts receiving active third line therapy for HER2+ MBC. Methods This retrospective study used data from US Oncology's iKnowMed electronic medical record system. Female pts with HER2+ MBC initiating a 1st line regimen containing trastuzumab from 1/1/2006 — 7/31/2007 were identified. Pts on clinical trials and those receiving concurrent treatment for other primary cancers were excluded. Pts were followed through 4/30/2010 to observe progression to 3rd line therapy and subsequent clinical outcomes. The Kaplan Meier method was used to estimate time to progression from 1st to 3rd line and subsequent overall survival in the 3rd line setting. Results We identified 139 pts who initiated a 1st line regimen containing trastuzumab between 1/1/2006 — 7/31/2007. A total of 92 pts (66%) progressed to 2nd line therapy and 48 patients (35%) experienced progression on 2nd line treatment and received active 3rd line therapy during the follow-up period. Median time to progression from 1st to 3rd line therapy of 35.0 months (95% CI: 30.7 — 39.3 months). Twenty-three pts (17%) died prior to progression to 3rd line (median time to death = 11.9 months; range = 1 — 40 months), while 68 pts (49%) were alive without progression to 3rd line at the end of the follow-up period. Of 48 pts who progressed during 2nd line and received 3rd line therapy, 29 (60%) pts received anti-HER2 targeted therapy in 3rd line (17 pts received trastuzumab and 12, lapatinib). Overall, the 5 most common 3rd line regimens included: lapatinib + capecitabine (N=12); trastuzumab + vinorelbine (N=8); trastuzumab + taxane (N=6); liposomal doxorubicin (N=4); and capecitabine (N=3). Following progression on 2nd line therapy, median overall survival was 11.2 months (95% CI: 7.7 — 14.7 months). Of the 48 pts who received active third line treatment, 27 (56%) subsequently progressed and received 4th line therapy. The most common 4th line regimens received included: nab-paclitaxel (N=4); lapatinib + capecitabine (N=3); gemcitabine (N=3); ixabepilone (N=3); trastuzumab monotherapy (N=2); and capecitabine (N=2). Of pts who progressed during 3rd line, only 7 (26%) pts who received active 4th line therapy received anti-HER2 targeted therapy (4 patients received trastuzumab and 3 received lapatinib). Conclusion Little is known regarding 3rd line or greater patterns of care and outcomes among HER2+ MBC pts receiving care in the outpatient community setting. In this retrospective study, about a third (35%) of pts received 3rd line therapy, with another 49% alive without progression to 3rd line during the observation period. 3rd and 4th line therapy utilization varied widely, suggesting that a standard of care has not emerged in this community-based setting. A majority of pts who progress during 2nd line continue to receive anti-HER2 targeted therapy in the 3rd line. Continued active therapy past 3rd line appears common in this setting; however results suggest that use of anti-HER2 targeted therapy may decrease in the 4th line setting. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-11-15.