Abstract OT1-16-01: A multicenter phase II study of vaccines to prevent recurrence in patients with HER-2 positive breast cancer

Background: HER2-positive breast cancer patients are commonly treated with neoadjuvant therapy including HER2-targeted therapy. Patients who have residual invasive disease have less favorable outcomes with an increased risk of recurrent disease than patients with complete pathologic response (pCR). It has also been observed that these non-pCR patients have low or absent anti-HER-2 CD4 Th1 responses. We hypothesized that correcting the anti-HER-2 CD4 Th1 response using vaccines will increase interferon gamma production which we have shown is a potent inducer of apoptosis and senescence in HER2-positive breast cancer. This study will be evaluating safety and immunogenicity of two vaccines (multivalent anti-oncodriver DNA vaccine (WOKVAC) or HER-2-pulsed dendritic cell vaccine (DC1)). Methods: This is a multi-center, phase 2, randomized study to determine the safety and tolerability of HER2 vaccines (DC1 and WOKVAC), assess immunogenicity, and evaluate recurrence free survival. Patients with HER2-positive early breast cancer (stage I-III) are eligible if they have residual invasive disease in the breast or axilla at surgery after receiving neoadjuvant chemotherapy plus HER2 -targeted therapy. Patients are randomly assigned in a 1:1 ratio to receive 1 of 2 adjuvant HER2 vaccines, either DC1 or WOKVAC for 1 year. A permuted-block randomization scheme was used with stratification according to residual cancer burden (RCB) (1+2 vs 3). The primary end points are safety and immunogenicity (immune response rate measured by ELISPOT). Each treatment arm will be assessed separately. Any statistical comparison between arms is purely exploratory, as this study is neither designed nor powered for comparative hypotheses. Secondary endpoints include recurrence-free survival. Exploratory analyses include the assessment of prognostic and predictive biomarkers including circulating tumor cells, serum HER2 levels, and other immune markers. The enrollment began in 2018 and we plan to accrue the total of 110 patients. ClinicalTrials.gov Identifier: NCT03384914 Citation Format: Hyo S Han, Mary Disis, Robert Wesolowski, Carla Fisher, Shipra Gandhi, Nancy Chan, William Gwin, Keerthi Gogineni, Rosemarie Mick, Christina Sierra Rodriguez, Deanna Hogue, Hien Liu, Ricardo Costa, Brian Czerniecki. A multicenter phase II study of vaccines to prevent recurrence in patients with HER-2 positive breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr OT1-16-01.