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

Cavanna, Luigi; Citterio, Chiara; Biasini, Claudia; Madaro, Serena; Bacchetta, Nicoletta; Lis, Anna; Cremona, Gabriele; Muroni, Monica; Bernuzzi, Patrizia; Lo Cascio, Giuliana; Schiavo, Roberta; Mutti, Martina; Tassi, Maristella; Mariano, Maria; Trubini, Serena; Bandieramonte, Giulia; Maestri, Raffaella; Mordenti, Patrizia; Marazzi, Elisabetta; Vallisa, Daniele

INTRODUCTION: Cancer patients 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 mRNA-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 study. The control group was composed of healthy volunteers. Serum samples were evaluated for SARS-COV-2 antibodies prior vaccinations and 2-6 weeks after the administration of the second vaccine dose. Primary endpoint: seropositivity rate. Secondary endpoints: safety, factors influencing seroconversion, IgG titers of patients versus healthy volunteers, COVID-19 infection. RESULTS: Between 20 March 2021 and 12 June 2021, 293 consecutive cancer patients with solid tumors underwent a program of COVID-19 vaccinations: of these, 2 patients refused vaccination, 13 did not receive the second dose of the vaccine due to cancer progression and 21 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 endpoint: seropositivity rate in patients was 75.88%, versus 100% in the control group. Secondary endpoints: 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 negatively seroconversion. BNT162b2 or mRNA-1273 vaccines were immunogenic in cancer patients, showing good safety profile.