Outcomes of neoadjuvant combination chemotherapy with and without targeted therapy in HER2-positive breast cancer: A real-world experience from tertiary care center in North India.

Abstract

e12601 Background: Neoadjuvant chemotherapy (NACT) with HER2 blockade is preferred approach for treatment of early and locally advanced HER2 positive breast cancer. However, there is a lack of survival data with respect to pathological complete response (pCR) from India. Methods: We retrospectively evaluated 211 HER2 positive female breast cancer patients registered between years 2014 and 2021, who received three different NACT regimens (i) Anthracycline free TCH (n=116) [docetaxel (75mg/m2), carboplatin (AUC = 6) and trastuzumab (8mg/kg loading followed by 6mg/kg) with G-CSF q 21 days], (ii) EC-TH (n=52) [epirubicin (90 mg/m2) and cyclophosphamide (600 mg/m2) for 4 cycles followed by 4 cycles of docetaxel (85mg/m2)] and (iii) EC-T (n=43, without trastuzumab due to financial constraints). Primary end point was pCR. Secondary end points were disease free survival (DFS), Overall Survival (OS) and safety profile. Results: Median age was 45 years (24-71), 88 (41.7%) were postmenopausal and 104 (49.3%) were ER/PR positive. Twenty-two (10.4%) patients were stage II, 164 (77.7.%) were stage III and 25 (11.9%) were oligometastatic stage IV. Distribution of age, performance status, tumor size and nodal positivity were comparable across the study groups. Pathological CR in trastuzumab containing groups, was higher compared to non-trastuzumab containing group (35.8% vs 20%, p=0.045) and was similar between, TCH and EC-TH groups. Median follow-up was 32.9 months (5.7-108), 3-year DFS and OS were 54.8% and 92.1% respectively. Pathological CR rates and survival outcomes of the three groups are given in table 1. When stratified by pCR status, in the trastuzumab containing groups, achievement of pCR translated to improved DFS (log rank p=0.01). This survival advantage of pCR was not seen in non-trastuzumab containing group. The outcome of trastuzumab containing both regimens were similar. Grade 3/4 toxicities were recorded in 21.6% of TCH, 26.7% of EC-TH and in 25.2% of EC-T groups. Most common toxicities were anemia (16.3%), thrombocytopenia (14.2%) and vomiting (10.2%). Conclusions: Trastuzumab containing regimens impact pCR rates and in turn the survival outcomes among Indian women with HER2 positive breast cancer. Safety and efficacy of anthracycline free TCH regimen is comparable with EC-TH.[Table: see text]