Predictors of poor seroconversion and adverse events to SARS-CoV-2 mRNA BNT162b2 vaccine in cancer patients on active treatment.

Abstract Purpose Initial findings in patients with cancer suggest a lower seroconversion to SARS-COV-2 vaccination possibly related to myelo-immunosuppressive therapies. We conducted a prospective study to assess factors predicting poor seroconversion and adverse events following immunization (AEFI) to the BNT162b2 vaccine in patients on active treatment. Patients and methods Cancer patients candidate to two doses of BNT162b2 SARS-COV-2 vaccination were enrolled. Patients on active surveillance served as controls. The primary endpoint was poor seroconversion (anti S1/S2 IgG Results Between March and July 2021, 320 subjects were recruited and 291 were assessable. The lack of seroconversion at 21 days from the second dose was 1.6% (95% CI, 0.4-8.7) on active surveillance, 13.9% (8.2-21.6) on chemotherapy, 11.4% (5.1-21.3) on hormone therapy, 21.7% (7.5-43.7) on targeted therapy and 4.8% (0.12-23.8) on immune-checkpoint-inhibitors (ICI). Compared to controls, the risk of no IgG response was greater for chemotherapy (P=0.033), targeted therapy (0.005) and hormonotherapy (P=0.051). Lymphocyte count Conclusion Chemotherapy, targeted therapy, hormone therapy, lymphocyte count