Resumption of Trastuzumab in Patients With Disease Recurrence After (Neo-) Adjuvant Anti-HER2-therapy in Patients With HER2-positive Breast Cancer.

Background/Aim: HER2-positive breast cancers eventually relapse in about one third of patients. Is anti-HER2-directed therapy with Herceptin (R) (trastuzumab) effective in retreatment? Between 2008 and 2018, 216 patients with recurrent HER2-positive breast cancer (BC) were re-treated with Herceptin (HER) during first-line therapy. This study assessed the effectiveness and tolerability of re-treatment with HER. Patients and Methods: After approval from Ethical committee, the NIS was conducted according to German Drug Act. Retreatment with HER was documented at routine visits starting with a basic observational period of maximum 12 months and a follow-up period of maximum additional four years. Results: HER2-positive BC relapsed after a median of 36.5 months (mos). Patients were re-treated with HER +/- chemotherapy +/- endocrine therapy. HER-containing regimens resulted in median progression-free survival (mPFS) of 12.7 (95%CI=10.5-14.8) mos and overall survival (OS-2) of 31.6 mos (95%CI=28.8-38.4) since recurrence diagnosis. Differentiation of recurrence types (local, visceral, non-visceral) unfolded worst prognosis for patients with visceral metastases. Cardiac monitoring within this non-interventional study (NIS) did not result in new safety concerns. Conclusion: Re-therapy with HER in the first-line setting of advanced HER2-positive breast cancer is effective and without unexpected or intensified adverse events.