Abstract P4-10-03: Immunogenicity of SARS-CoV-2 vaccination in subjects on active treatment for breast cancer

Background: Infection with SARS-CoV-2 has led to a global pandemic and has significantly impacted the care of cancer patients. Breast cancer patients receiving active systemic therapy need protection against COVID19 but the efficacy of vaccines in this population is unknown. Although specific biomarkers associated with protection from SARS-CoV-2 infection have yet to be identified, measurement of serum antibody activity is generally accepted as a surrogate of in vivo humoral response to vaccine. This study evaluates the efficiency and durability of binding antibodies to SARS-CoV-2 spike (S) protein in response to COVID19 vaccine in breast cancer patients receiving systemic treatment. Methods: Breast cancer patients, who were unvaccinated, partially or fully vaccinated with Pfizer-BioNTech BNT162b2 (PF), Moderna mRNA-1273 (Mod) or Johnson & Johnson AD26.COV2.S (J&J) were enrolled in this prospective longitudinal study. Eligible patients were on systemic treatment with cytotoxic chemotherapy, chemotherapy plus a checkpoint inhibitor (CPI), CPI alone or a CDK 4/6 inhibitor. Longitudinal blood samples are being collected at baseline, prior to vaccination in unvaccinated patients (T0), 2 weeks after the first vaccine dose and before the second dose for the mRNA vaccines (T1), 1 month (T2), 3 months (T3), 6 months (T4) and 12 month post vaccination. For J&J, there was no T1 timepoint. Roche Elecsys® Anti-SARS-CoV-2 S receptor binding domain (RBD) antibody immunoassay was used to measure antibody titers (range 0.4 to 250 U/mL). Cut points of N% Seropositive (>0.8 U/mL)Mean Antibody Levels (U/mL)T0T1T2T3T0T1T2T3All subjects7510789810012.6102.3204.4214.6Chemotherapy50577961003.3105.6200.0250CDK 4/6 inhibitors15257510010013.786.8234.7205.8CPI + Chemotherapy82583100NA*62.8121.4177.5NA*CPI therapy20100100NA*0.46.82250NA*CPI=Checkpoint Inhibitors; *Timepoint for longitudinal samples not reached Citation Format: Cory Bivona, Kevin Li, Priyanka Sharma, Jianghua He, Grace Martin, Andrew K Godwin, Anthony Rooney, Stephen Williamson, Gary Doolittle, Weijing Sun, Bruce F Kimler, Anne P O'Dea, Lauren E Nye, Joseph P McGuirk, Ziyan Pessetto, Lisa Haney, Nicole Balmaceda, Laura Mitchell, Karissa Finke, Maggie Nelson, Dinesh Pal Mudaranthakam, Natalie Streeter, Stephanie Lafaver, Jaimie Heldstab, Qamar J Khan. Immunogenicity of SARS-CoV-2 vaccination in subjects on active treatment for 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 P4-10-03.