Efficacy of pertuzumab in combination with trastuzumab and a taxane in first-line treatment for metastatic breast cancer (MBC): A multicenter, retrospective, observational study.

Abstract

e12504 Background: Pertuzumab (P) , Trastuzumab (T) and Docetaxel (D) is standard first-line treatment in patients (pts) with HER2 + metastatic breast cancer (MBC). This multicenter retrospetive observational study was performed to evaluate the activity of P and T in combination with D or Paclitaxel (Tx) in real world HER2 + MBC pts. Methods: We identified HER2 + MBC pts treated with P, T and D or Ptx optionally followed by P, T and endocrine therapy (ET) maintenance in hormone positive (HR+) BC, in 17 Italian cancer centres between 09/2012 and 08/2016. Overall Survival (OS) and Progression Free Survival (PFS) were calculated by the Kaplan-Meier product-limit method. Log-rank test was used to assess differences between subgroups. Results: 191 pts were included in our analysis. Pts characteristics: median age 54 years (range 29-80); PS 0 in 127 (67%) pts and PS 1 in 54 (28%); 107 (56%) had visceral metastases (mts), 23 (12%) only bone mts and 28 (15%) brain mts, 130 (68%) were ER/PgR +. 76 pts (40%) were metastatic at diagnosis; 148 (78) were treated with D while 43 (22%) with Tx. The ORR was 78% (CI 95% 72-84), RC 18% and RP 60%, only 10 (5%) had PD. To date, of the 54 pts treated with ET maintenance, 26% had a further improvement of response (7 pts had RC). At median follow-up of 17 months (mo) (range 6- 52), median PFS was 20 mo (95% CI 14-26) and median OS at 2 years was 80%. No differences in PFS were found for age (p = 0.92), PS (p = 0.18), receptor status (p = 0.57), visceral mts (p = 0.54) and chemotherapy (cht) type (p = 0.47), whereas number of mts site (1 vs > 1) affected PFS (28 vs 16 mo, p = 0.002). Moreover median PFS in naïve pts and in pts pretreated with only cht was 28 mo (95% CI, 20-36) and 27 mo (95% CI, 16-38) respectively, whereas in pts pretreated with T it was 12 mo (95% CI 16-38 p 0.002). In HR+ pts ET maintenance together with P and T had an impact on PFS (28 vs 15 mo, p = 0.01). Conclusions: Our analysis confirms, in real world HER2 MBC pts, the efficacy of P, T and a taxane combination in first line treatment; in this population PFS was shorter in pts pretreated with T. ET maintenance in association with P and T in HR+ pts improved PFS. Data collection is ongoing and update results will be presented.