Background Cancer patients are at higher risk of developing severe COVID-19. However, safety and efficacy of COVID-19 vaccination in cancer patients undergoing treatment is unclear. Patients and Methods In this interventional prospective multi-cohort study, priming and booster doses of the BNT162b2 COVID-19 vaccine were administered 21 days apart to solid tumor patients receiving chemotherapy, immunotherapy, targeted- or hormonal therapy, and patients with a hematologic malignancy receiving rituximab or after allogeneic hematopoietic stem cell transplantation. Vaccine safety and efficacy (until three months post-booster) were assessed. Anti-SARS-CoV-2 receptor binding domain (RBD) antibody levels were followed over time (until 28 days post-booster) and in vitro SARS-CoV-2 50% neutralization titers (NT50) towards the wild-type Wuhan strain were analyzed 28 days post-booster. Results Local and systemic adverse events (AEs) were mostly mild to moderate (only 1-3% of patients experiencing severe AEs). Local, but not systemic, AEs occurred more frequently after booster dose. 28 days post-booster vaccination of 197 cancer patients, RBD-binding antibody titers and NT50 were lower in the chemotherapy group (234.05IU/mL [95%CI 122.10-448.66] and NT50 of 24.54 [95% CI 14.50-41.52]) compared to healthy individuals (1844.93IU/mL [95% CI 1383.57-2460.14] and NT50 of 122.63 [95% CI 76.85-195.67]), irrespective of timing of vaccination during chemotherapy cycles. Extremely low antibody responses were seen in hematology patients receiving rituximab, only two patients had RBD-binding antibody titers necessary for 50% protection against symptomatic SARS-CoV-2 infection (<200IU/mL) and only one had NT50 above the limit of detection. During the study period, five cancer patients tested positive for SARS-CoV-2 infection, including a case of severe COVID-19 in a patient receiving rituximab, resulting in a 2-week hospital admission. conclusion The BNT162b2 vaccine is well-tolerated in cancer patients under active treatment. However, the antibody response of immunized cancer patients was delayed and diminished, mainly in patients receiving chemotherapy or rituximab, resulting in breakthrough infections.

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BackgroundPatients with cancer, especially hematological cancer, are at increased risk for breakthrough COVID-19 infection. So far, a predictive biomarker that can assess compromised vaccine-induced anti-SARS-CoV-2 immunity in cancer patients has not been proposed.MethodsWe employed machine learning approaches to identify a biomarker signature based on blood cytokines, chemokines, and immune- and non-immune-related growth factors linked to vaccine immunogenicity in 199 cancer patients receiving the BNT162b2 vaccine.ResultsC-reactive protein (general marker of inflammation), interleukin (IL)-15 (a pro-inflammatory cytokine), IL-18 (interferon-gamma inducing factor), and placental growth factor (an angiogenic cytokine) correctly classified patients with a diminished vaccine response assessed at day 49 with &gt;80% accuracy. Amongst these, CRP showed the highest predictive value for poor response to vaccine administration. Importantly, this unique signature of vaccine response was present at different studied timepoints both before and after vaccination and was not majorly affected by different anti-cancer treatments.ConclusionWe propose a blood-based signature of cytokines and growth factors that can be employed in identifying cancer patients at persistent high risk of COVID-19 despite vaccination with BNT162b2. Our data also suggest that such a signature may reflect the inherent immunological constitution of some cancer patients who are refractive to immunotherapy.

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