This observation does not necessarily translate into reduced protection after ChAdOx1, however, as no correlate of protection has yet been defined. booster dose were administered with an interval of 21 days 2 days for 95% and 24-27 days for 5% of the subjects for BNT162b2 (2 30 g) and 12 weeks 10 days for 90% and 8-10 weeks for JK 184 10% of the subjects for ChAdOx1 vaccination (2 0.5 ml). Subjects with a solid tumor (77.7%) were divided into three treatment cohorts: chemotherapy, immunotherapy, and targeted/hormonal therapy. A differentiation for hematologic patients (19.7%) was made between patients receiving rituximab and patients who have undergone hematopoietic stem cell transplantation more than 1 year ago. Therapy cohorts were based on the type of antineoplastic treatment the patients received at the time of the priming dose. Anti-S1 antibody titers were tested using the Atellica IM SARS-CoV-2 IgG (sCOVG) assay (Siemens Healthineers, Erlangen, Germany) pre-priming and 28 days post-booster (Supplementary Table?S1, available at Log-transformed immunoglobulin G titers were compared using a 0.05] (Figure?1A, Supplementary JK 184 Table?S1, available at? The differences remained present after exclusion of 22 participants (6.4%) with detectable pre-priming antibody titers. Subanalysis showed significantly lower post-booster antibody titers after ChAdOx1 compared with BNT162b2 vaccination in patients receiving immunotherapy [5.28 U/ml (95% CI 2.58-10.82 U/ml) versus 35.0 4 U/ml (95% CI 13.82-88.86 U/ml), 0.05]. In?contrast, antibody titers were not significantly different between both vaccine types in patients receiving chemotherapy or in hematologic patients (Physique?1B). Open in a separate window Figure?1 Humoral immune response 28 days post-booster dose in cancer patients vaccinated with the BNT162b2 or ChAdOx1 Rabbit Polyclonal to PTRF vaccine. Violin plots of log-transformed SARS-CoV-2 anti-S1 IgG antibody titers 28 days after booster dose in the entire study population (panel A) and in different treatment cohorts (panel B). Inside each violin plot, the geometric mean titer (GMT) is usually depicted as a point. Anti-S1 IgG-class antibody titers were quantified using a SARS-CoV-2 immunoassay, Siemens Healthineers Atellica IM SARS-CoV-2 IgG (sCOVG) assay for the detection of antibodies (models/ml). The measuring interval is usually 1.00-750.00 U/ml; values below this interval JK 184 were imputed to 1 1.00 U/ml, values above this interval were imputed to 1000 U/ml with dotted lines indicating lower limit of quantitation (LLQ) and upper limit of quantitation (ULQ), respectively. HSCT, hematopoietic stem cell transplantation; IgG, immunoglobulin G. While both BNT126b2 and ChAdOx1 vaccines elicit a clear antibody response, dual-dose BNT162b2 elicits higher anti-S1 antibody levels compared with dual-dose ChAdOx1 vaccination in our cancer population. This observation does not necessarily translate into reduced protection after ChAdOx1, however, as no correlate of protection has yet been defined. Significant differences between antibody responses after dual dose BNT162b2 and ChAdOx1 vaccination were seen in patients receiving targeted/hormonal therapy and immunotherapy, but not in other treatment cohorts. Hence, it is unsure how these differences might affect cellular immunity and neutralizing antibody titers against the JK 184 Wuhan SARS-CoV-2 strain and the different occurring SARS-CoV-2 variants. Given the additional value of the administration of a third vaccination dose in cancer patients, however, as shown in recent studies, a third dose of BNT162b2 after full ChAdOx1 vaccination might be prioritized in cancer patients.4,5 Acknowledgements We are grateful JK 184 to the B-VOICE and Tri-VOICE plus study teams for patient inclusion and sample collection. They were not compensated for their contribution. We also want to thank all our patients for study participation. Funding None declared. Disclosure The authors have declared no conflicts of interest. Supplementary data Supplementary Table?S1:Click here to view.(14K, docx).