COVID-19 vaccines in adult cancer patients with solid tumours undergoing active treatment: Seropositivity and safety. A prospective observational study in Italy

Introduction: Patients with cancer are presumed a frail group at high risk of contracting coronavirus disease (COVID-19), and vaccination represents a cornerstone in addressing the COVID-19 pandemic. However, data on COVID-19 vaccination in cancer patients are fragmentary and poor.

Methods: An observational study was conducted to evaluate the seropositivity rate and safety of a two-dose regimen of the BNT162b2 or messenger RNA-1273 vaccine in adult patients with solid cancer undergoing active anticancer treatment or whose treatment had been terminated within 6 months of the start of the study. The control group was composed of healthy volunteers. Serum samples were evaluated for SARS-COV-2 antibodies before vaccinations and 2-6 weeks after the administration of the second vaccine dose. Primary end-point: seropositivity rate. Secondary end-points: safety, factors influencing seroconversion, IgG titers of patients versus healthy volunteers, COVID-19 infection.

Results: Between 20th March 2021 and 12th June 2021, 293 consecutive patients with cancer-solid tumours underwent a program of COVID-19 vaccinations; of these, 2 patients refused vaccination, 13 patients did not receive the second dose of the vaccine because of cancer progression, and 21 patients had COVID-19 antibodies at baseline and were excluded. The 257 evaluable patients had a median age of 65 years (range 28-86), 66.15% with metastatic disease. Primary end-point: seropositivity rate in patients was 75.88% versus 100% in the control group. Secondary end-points: no Grade 3-4 side-effects, no COVID-19 infections were reported. Patients median IgG titer was significantly lower than in the control group; male sex and active anticancer therapy influenced negative seroconversion. BNT162b2 or messenger RNA-1273 vaccines were immunogenic in cancer patients, showing good safety profile.