Abstract P4-12-16: Safety profile and costs of related adverse events of trastuzumab emtansine compared to other regimens in the Canadian health care system
Authors: Piwko C , Yunger S , Moser A , Peter L , Vicente C 
Published: August 2014

Abstract
Background
Trastuzumab Emtansine (T-DM1) is an antibody–drug conjugate (ADC) comprised of the microtubule inhibitory cytotoxic agent DM1 and trastuzumab which, in addition to its antitumor properties, targets T-DM1 to HER2–overexpressing cells. The phase III EMILIA study compared the safety and efficacy of T-DM1 (n = 496) versus capecitabine plus lapatinib (CAP+LAP, n = 495) in patients with HER2-positive locally advanced or MBC previously treated with trastuzumab and a taxane. The phase II TDM4450g study compared the safety and efficacy of T-DM1 (n = 67) versus trastuzumab plus docetaxel (TRAZ+DOCE, n = 70) in patients with previously untreated MBC. These trials demonstrated statistically and clinically meaningful differences between T-DM1 and its comparators. In the EMILIA trial, the proportion of patients who developed grade ≥3 treatment-related AEs that were deemed related to treatment by the investigators was lower in the T-DM1 arm (30.6%) compared to the CAP+LAP arm (48.8%) and 5.9% of patients on T-DM1 discontinued treatment due to an AE, compared with 10.7% of patients on CAP+LAP.
In the TDM4450g study, the proportion of patients who developed grade ≥3 AEs that were deemed related to treatment by the investigators was lower in the T-DM1 arm (33.3%) versus the TRAZ+DOCE arm (81.82%) and 7.2% of patients on T-DM1 discontinued treatment due to an AE, compared with 34.8% of patients on TRAZ+DOCE.
The objective of this analysis was to estimate and compare the Canadian costs of managing the treatment-related AEs of T-DM1 as reported in the EMILIA and TDM4450g trials, from the perspective of Canadian public payers.
Methods
An Excel based spreadsheet model was utilized to estimate the costs of managing the treatment-related AEs. Clinical data (number and severity of AEs) were obtained from the two trials. Resource utilization and costing information were obtained from the literature, clinical experts, and Canadian standard costing sources (minimum and maximum costs were used). Costs were reported as 2012 CAD. The AEs that were considered for costing in this analysis were all treatment-related grade ≥3 AEs as well as grade 2 AEs that occurred in ≥5% of patients in both arms of either study.
Results
The management of treatment-related AEs by using T-DM1 resulted in cost savings ranging from $1,684 - $8,036 versus CAP+LAP as reported in the EMILIA trial and from $4,326 - $25,402 versus TRAZ+DOCE as per the TDM4450g trial (see Table 1).
Table 1: Range of Costs of Managing Treatment-Related AEs as Reported in the EMILIA and TDM4450g trials EMILIATDM4450g T-DM1CAP + LAPT-DM1TRAZ+DOCECost per patient$1,376 - $2,463$3,060 - $10,499$798 - $2,215$5,124 - $27,617Cost savings$1,684 - $8,036$4,326 - $25,402
Conclusions
This analysis demonstrated that utilizing T-DM1 for the management of HER2-positive MBC results in significant cost savings of related AEs management due to the improved safety profile compared to CAP+LAP and TRAZ+DOCE.
Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-12-16.