A retrospective, multicenter study of the efficacy of lapatinib plus trastuzumab in HER2-positive metastatic breast cancer patients previously treated with trastuzumab, lapatinib, or both: the Trastyvere study
J Gavilá 1 , J De La Haba 2 , B Bermejo 3 , Á Rodríguez-Lescure 4 , A Antón 5 , E Ciruelos 6 , J Brunet 7 , E Muñoz-Couselo 8 , M Santisteban 9 , C A Rodríguez Sánchez 10 , A Santaballa 11 , P Sánchez Rovira 12 , J Á García Sáenz 13 , M Ruiz-Borrego 14 , A L Guerrero-Zotano 1 , M Huerta 3 , A Cotes-Sanchís 4 , J Lao Romera 5 , E Aguirre 15 , J Cortés 16 17 18 , A Llombart-Cussac 19 20
Purpose: To evaluate the efficacy and safety of lapatinib (L) and trastuzumab (T) combination in HER2-positive metastatic breast cancer (MBC) patients previously treated with T and/or L.
Materials and methods: We conducted a retrospective, post-authorized, multicenter study including patients with HER2-positive MBC or locally advanced breast cancer (ABC) treated with the combination of L-T. Concomitant endocrine therapy, as well as brain metastasis and/or prior exposure to L, were allowed.
Results: One hundred and fifteen patients from 14 institutions were included. The median age was 59.8 years. The median number of prior T regimens in the advanced setting was 3 and 73 patients had received a prior L regimen. The clinical benefit rate (CBR) was 34.8% (95% CI 26.1-43.5). Among other efficacy endpoints, the overall response rate was 21.7%, and median progression-free survival (PFS) and overall survival were 3.9 and 21.6 months, respectively. Heavily pretreated and ≥ 3 metastatic organ patients showed lower CBR and PFS than patients with a low number of previous regimens and < 3 metastatic organs. Moreover, CBR did not significantly change in L-pretreated compared with L-naïve patients (31.5% versus 40.5% for L-pretreated versus L-naïve). Grade 3/4 adverse events were reported in 19 patients (16.5%).
Conclusion: The combination of L-T is an effective and well-tolerated regimen in heavily pretreated patients and remains active among patients progressing on prior L-based therapy. Our study suggests that the L-T regimen is a safe and active chemotherapy-free option for MBC patients previously treated with T and/or L.