Clinico-pathological predictors of radiologic complete response to first-line anti-HER2 therapy in metastatic breast cancer

This study aimed to identify the clinico-pathological variables predictive of radiologic complete response (rCR) to first-line anti-HER2 therapy in patients with HER2-positive metastatic breast cancer. Patients were selected from the database of the GIM14 study and classified according to the best radiologic response obtained to first-line anti-HER2 therapy and upon time-to-treatment-discontinuation (TTD). A total of 545 patients were included in the analysis. Eighty patients experienced a rCR to first-line anti-HER2 therapy with a TTD > 3 months and HER2 Immunohistochemistry score 3+, presence of non-visceral metastases and 1 metastatic site were significantly associated with higher odds of obtaining a CR. Of the 80 patients achieving a rCR, 56 experienced a CR with a TTD > 18 months, with anti-HER2 therapy being the only variable significantly associated with a higher probability of achieving such sustained CR.