Immunogenicity and safety of COVID-19 vaccine BNT162b2 for patients with solid cancer: a large cohort prospective study from a single institution.

Purpose We assessed the immunogenicity and safety of the BNT162b2 vaccine in a large cohort of patients with cancer (CP). Experimental design From March 1st-20th,2021, this prospective cohort study included 816 CP afferent to our Institution and eligible to the vaccination. A cohort of 274 healthcare workers (HCW) was used as age and sex-matched control-group. BNT162b2 was administered at two-dose regimen given 21-days apart. Blood samples to analyze anti-Spike (S) IgG antibodies (abs) were collected pre-vaccination (time-point [TP] 0), at 3 (TP1) and 7 week (TP2) after the first dose. Results Patients characteristics: median age 62 (range 21-97); breast/lung cancer/others (31/21/48%); active treatment/follow-up (90/10%). In the whole CP cohort, the serological response rate (RR) and the titre of anti-S IgG significantly increased across the TPs; at TP2, the responders (Ig-G >15 AU/ml) were 94.2%. Active chemotherapy and chronic use of steroids were independent predictors of lower RR. Adverse events (AE) after the booster predicted higher likelihood of response (odds ratio 4.04, 95%CI 1.63-9.99, p=0.003). Comparing the matched cohorts, the responders were significantly lower in CP than in HCW at TP1 (61.2% vs 93.2%) and TP2 (93.3% vs 100%), while the geometric mean concentration of IgG did not significantly differ at TP2 being significantly lower in CP (23.3) than in HCW (52.1) at TP1.BNT162b2 was well tolerated in CP: severe grade AE were 3.5% and 1.3% after the first and second doses, respectively. Conclusions BNT162b2 assures serological immunization without clinically significant toxicity in CP.The second dose is needed to reach a satisfactory humoral response.