Schmid S, Klingbiel D, Aebi S, et al. - In the SAKK 22/99 trial, HER2-targeted therapy alone followed by the addition of chemotherapy vs upfront combination were examined for their influence on the disease progression. Researchers sought to characterize the specific subset of patients deriving long-term benefit from trastuzumab monotherapy alone, in addition to identifying potential predictive factors of long-term response via conducting an exploratory analysis of the SAKK 22/99 trial. Eighty-six patients were randomized to trastuzumab monotherapy. Of these, 24 patients (28%) were long-term responders and 62 (72%) were short-term responders with a 5y-overall survival of 54% and of 18%, respectively. Negative predictive factors for durable clinical benefit were an absence of ER expression, absence of PgR expression and presence of visceral disease. These findings suggest that a subgroup of HER2-positive patients with advanced disease could achieve durable clinical benefit with trastuzumab monotherapy.