Abstract P4-16-03: Cardiovascular outcomes and long term survival with discontinuation of adjuvant trastuzumab
Authors: Sardesai S , Liu J , Palettas M , Stephens J , Stover D , Williams N , Reinbolt R , VanDeusen J , Wesolowski R , Lustberg M , Ramaswamy B 
Published: May 2019

Abstract
Background: Trastuzumab (T) induced cardiomyopathy remains a significant limitation to adjuvant HER2 directed therapy. Recent studies have aimed to reduce cardiotoxicity through combination with non-anthracycline (non-A) chemotherapy or shorter treatment duration. However there is limited data regarding cardiac outcomes and long-term survival with early discontinuation of adjuvant T.
Methods: An IRB-approved single-institution retrospective analysis was performed for 401 consecutive patients with non-metastatic HER2+ breast cancer treated at the Ohio State University Comprehensive Cancer Center from 2005-2015. Medical records were reviewed for clinicopathologic features, systemic treatment and survival information. Disease Free Survival (DFS) was defined as time from diagnosis to first recurrence (loco-regional or distant recurrence) including second primary breast cancer or death. Overall survival (OS) was defined as time from diagnosis to death or last known follow up. OS and DFS estimates were generated using Kaplan Meier methods and compared using Log-rank tests. Cox proportional hazard models were used to calculate univariate and multivariate hazard ratios for OS and DFS.
Results: A total of 371/401 (92.5%) patients received adjuvant T (n= 401, mean age: 59.4 years; stage 1: 120, 30%; stage II: 194, 48%; stage III: 87, 22%; ER+: 235, 58%); among whom 106/371 (28.6%) patients held adjuvant T for any reason. Median duration of therapy in patients with any interruption with T was 11.3 (0.5-16.9) months and 23/371 (6.9%) received less than 6 months of adjuvant T. Cardiomyopathy (measured as LVEF decline on 2D echocardiogram or MUGA &gt;= 15 points) was the most common reason for withholding T (66/106, 62.3%). The majority of these patients received a cardiology referral (77/ 106, 72.6%) with a 13 day mean time to evaluation in outpatient clinic. Patients receiving non-A chemotherapy and beta blockers or ACE inhibitors during treatment were significantly less likely to experience cardiomyopathy (A vs non-A: 49/190, 25.8% vs. 16/136, 11.8% p=0.002); (Med vs no Med: 7/148, 4.73% vs 59/184, 32.1%; p&lt;0.001). Log-rank tests indicate a significant worsening in OS and DFS for patients who discontinued T (p=0.021, 0.001 respectively). Multivariate analyses confirmed significant worsening in DFS after adjusting for age, stage, ER , node status, and cardiomyopathy (Adjusted HR: 4.0[2.02 – 7.92], p&lt; 0.001)
Table 1- Discontinuation of adjuvant trastuzumab Number of patients (%)Initial treatment371Completed therapy with no interruption265 (71.4)Interruption of therapy for minimum of 2 weeks64 (17.2)Permanently discontinued42 (11.3)
Conclusion: Discontinuation of adjuvant trastuzumab, most often from cardiomyopathy, is an independent prognostic marker for worse DFS in non-metastatic HER2 positive breast cancer. Non-anthracycline chemotherapy and use of cardio-protective medication is associated with significantly reduced incidence of cardiotoxicity in this population. Future prospective studies should consider optimizing cardiovascular function to avoid interruption in adjuvant HER 2 directed therapy.
Citation Format: Sardesai S, Liu J, Palettas M, Stephens J, Stover D, Williams N, Reinbolt R, VanDeusen J, Wesolowski R, Lustberg M, Ramaswamy B. Cardiovascular outcomes and long term survival with discontinuation of adjuvant trastuzumab [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-16-03.