A de-escalated, chemotherapy-free neoadjuvant regimen of letrozole plus dual HER2 blockade showed promise in patients with HER2+/HR+ breast cancer who first achieved a molecular response to 2 weeks of letrozole, according to findings from the phase II PerElisa study presented at the 2018 ASCO Annual Meeting.
Between January 2014 and July 2017 64 patients across 8 institutions were enrolled in PerElisa. Patients received 2 weeks of letrozole followed by a core biopsy for molecular response assessment. The study defined molecular response as Ki67 reduction of >20% from baseline. Among evaluable patients, there were 44 patients with a molecular response and 17 patients who did not reach a molecular response.
Nine (20.5%) of the 44 molecular responders then achieved a pathologic complete response (pCR) to the de-escalated, chemotherapy-free regimen of letrozole plus trastuzumab (Herceptin) and pertuzumab (Perjeta), meeting the primary endpoint of the study. Also in these patients, the breast objective response rate was 74%. Additionally, the rate of breast conserving surgery (BCS) was 65.9% and the rate of conversion from mastectomy to BCS was 54.5%.
... to read the full story