TDM-1 efficacy in trastuzumab-pertuzumab pre-treated HER2 positive metastatic breast cancer patients: A meta-analysis.

person Claudia Omarini University Hospital of Modena, Modena, Italy info_outline Claudia Omarini, Federico Piacentini, Isabella Sperduti, Krisida Cerma, Monica Barbolini, Fabio Canino, Cecilia Nasso, Massimo Dominici, Luca Moscetti

Authors person Claudia Omarini University Hospital of Modena, Modena, Italy info_outline Claudia Omarini, Federico Piacentini, Isabella Sperduti, Krisida Cerma, Monica Barbolini, Fabio Canino, Cecilia Nasso, Massimo Dominici, Luca Moscetti Organizations University Hospital of Modena, Modena, Italy, Regina Elena National Cancer Institute IRCCS, Biostatistics, Rome, Italy, Department of Oncology, University of Modena and Reggio Emilia, Modena, Italy, University of Modena and Reggio Emilia, Modena, Italy Abstract Disclosures Research Funding No funding received None Background: Based on the results reported in Emilia trial population, current guidelines consider TDM-1 the standard second-line therapy for HER2 positive metastatic breast cancer (MBC) patients. Despite that, there are no prospective studies supporting the efficacy of TDM-1 following trastuzumab (T) + pertuzumab (P) and taxane first-line treatment. Currently, only real-world data have investigated this sequence with controversial results Methods: We performed a meta-analysis of the available real world data to determine the efficacy of TDM-1 after first-line TP in HER2 positive MBC patients. We used a random-effect model to find differences in the rate of 1-year progression free survival (PFS) between TP pre-treated population and the phase III Emilia trial (T pre-treated population). Results: Seven studies were eligible, in three of them data were from sub-group population analysis. The meta-analysis showed a combined 1-years PFS risk difference for TDM-1 efficacy after TP in second or more lines of -0.122, with lower and upper limits of -0.253 and 0.010, respectively (p=0.07) , with low heterogeneity among studies (I 2 < 0.0001, p =0.836). Considering the four studies on TDM-1 in second-line setting, 1-years PFS risk was -0.034 (95% CI -0.207 – 0,139; p=0.701) (I 2 < 0.0001, p =0.91). Conclusions: Results from the meta-analysis show that the efficacy of TDM-1 after TP double-block seems to be similar to the previously reported in Emilia trial. In the second line setting, available data are not mature enough to confirm TDM-1 efficacy in TP pre-treated population. Currently, TP pretreated patients should receive TDM-1 as indicated in the guidelines.