Efficacy of SARS-CoV-2 vaccination in cancer patients during treatment: A prospective observational study (ANTICOV trial)

ABSTRACT

Background: Cancer patients (pts) have higher risk of serious COVID-19 symptoms, morbidity and mortality than general population. SARS-CoV-2 vaccine trials excluded patients with metastatic cancer or undergoing immunosuppressive therapies;therefore, the effectiveness of vaccines are unknown in this population. Hence, there is an urgent need to understand the correlation between cancer type, its treatment and vaccine efficacy. Material and Methods: This is a prospective study conducted by the Oncology Unit of Cremona Hospital, enrolling pts from Oncology, Hematology, Radiotherapy and Palliative Care divisions. The trial aims to evaluate effectiveness of mRNA vaccines [BNT162b2 (Pfizer) and mRNA-1273 (Moderna)], incidence of symptomatic COVID-19 infection, antibodies (Abs) response in a consecutive population of 300 cancer pts, undergoing antiblastic therapies, starting from March 2021. Primary endpoint Number of symptomatic pts affected by COVID-19, diagnosed 7-60 days after the 2nddose of vaccines. Secondary endpoints Abs variation at different timepoints;duration of abs;correlation between effectiveness of vaccines and antiblastic treatments. Statistical Analysis: The primary objective will be tested by non-inferiority one-single proportion test, compared with the value of 95% observed in the vaccine registration trials. The hypothesis of vaccine inferiority in the trial population is rejected if a rate of protection conferred by the vaccine is observed in 89% of the sample size. Results: 356 patients received mRNA anti-COVID-19 vaccines. None of them reported symptomatic COVID-19 infection after vaccination. Whereas almost all patients (95.6%) with solid tumors developed an antibody response, only 77% of patients with hematological malignancy demonstrated anti-COVID-19 antibody production after vaccination. The different antiblastic treatments didn't have a significant impact on the antibody response. In particular, patients treated with immunotherapies and with chemotherapy developed antibodies against COVID-19 in 98% and 92% of cases, respectively. Conclusions: Vaccination against COVID-19 demonstrated to be effective and to prevent symptomatic COVID- 19 infection in patients with solid and hematological tumors during antiblastic treatment. The depth of antibody response resulted different between patients with solid and hematological malignancies. Different antiblastic therapies didn't significantly impact on the development of the antibody response.