Abstract PO1-28-08: The Efficacy and Safety Results of Neoadjuvant Phase II study of Anlotinib plus Sintilimab Combined with Chemotherapy in Triple-negative Breast Cancer (NeoSACT)

Abstract Background: In triple-negative breast cancer (TNBC), the co-administration of programmed mortality 1 (PD-1) inhibitors and chemotherapy has demonstrated enhanced pathological complete response (pCR) rates and improved event-free survival (EFS). Previous research has suggested that antiangiogenic agents possess the ability to normalize aberrant tumor vasculature, thereby converting the immune-suppressive tumor microenvironment into an immune-supportive one. This study aims to assess the effectiveness and safety of combining the neoadjuvant small-molecule antiangiogenic drug Antilotinib with the PD-1 inhibitor Sintilimab and chemotherapy. Methods: In this study, a single-arm, open-label, phase II trial was conducted to evaluate the effectiveness of Anlotinib plus Sintilimab, in conjunction with nab-paclitaxel and carboplatin, followed by epirubicin and cyclophosphamide, in eligible patients with stage II-III TNBC. The treatment regimen consisted of four cycles of nab-paclitaxel (100 mg/m² on day 1, 8 and 15) plus carboplatin (AUC 5) every 21 days, followed by four cycles of epirubicin (90 mg/m2) plus cyclophosphamide (600 mg/m2) every 21 days. Additionally, patients received Sintilimab (200mg) every 21 days and Antilotinib (12mg, po on day 1-14, every 21 days) for eight cycles. Patient enrollment was conducted according to a Simon two-stage design. The primary endpoint was the rate of pCR based on the definition of ypT0/Tis ypN0. Secondary endpoints included residual cancer burden (RCB), EFS, overall survival (OS), adverse events (AE), and immune response biomarkers. Results: Between September 2021 and August 2023, a cohort of 31 patients was enrolled, with a median age of 48 years (range: 30-70 years). Among the participants, 21 out of 31 (67.8%) presented with clinical stage II disease, 23 out of 31 (74.2%) had T2 tumors, and 19 out of 31 (61.3%) exhibited clinically positive lymph nodes. In the initial phase of the study, a total of 11 patients were evaluated, out of which 7 patients achieved a pathological complete response (pCR) after surgery. Consequently, 20 patients were included in the subsequent stage, and among the 19 patients who were evaluable, 13 achieved pCR. One participant withdrew from the study prematurely following the third cycle due to grade 3 liver impairment, resulting in the discontinuation of study therapy as well as subsequent surgery. In the intention-to-treat (ITT) population, the overall pCR rate was determined to be 64.5% (20/31, 95% CI 45.4% - 80.8%). Additionally, 80.6% (25/31, 95%CI 62.5% - 92.5%) of the patients were assessed as having a RCB score of 0 or 1. A total of 31 patients were subjected to adverse event assessment. Among them, 12 patients (38.7%) experienced one or more grade 3/4 adverse events (AEs) according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. The grade 3/4 AEs encompassed rash (7 patients, 22.6%), anemia (4 patients, 12.9%), thrombocytopenia (3 patients, 9.7%), neutropenia (2 patients, 6.4%), leukopenia (2 patients, 6.4%), hypothyroidism (2 patients, 6.4%), and elevated AST/ALT (1 patient, 3.2%). Conclusions: The neoadjuvant regimen comprising the combination of Anlotinib and Sintilimab alongside chemotherapy demonstrated a pCR rate of 64.5%, with no observed emergence of novel toxicity signals. Ongoing investigations encompass biomarker assessments and survival analyses. Pertinent clinical trial details can be found under the identifier NCT04877821. Citation Format: Liulu Zhang, Mei Yang, Ciqiu Yang, Teng Zhu, Hong-Fei Gao, Kun Wang. The Efficacy and Safety Results of Neoadjuvant Phase II study of Anlotinib plus Sintilimab Combined with Chemotherapy in Triple-negative Breast Cancer (NeoSACT) abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-28-08.