SARS-CoV-2 Antibody Response to 2 or 3 Doses of the BNT162b2 Vaccine in Patients Treated With Anticancer Agents

IMPORTANCE Patients with solid cancer are more susceptible to develop SARS-CoV-2 infection and severe complications; the immunogenicity in patients treated with anticancer agents remains unknown. OBJECTIVE To assess the immune humoral response to 2 or 3 doses of the BNT162b2 (BioNTech; Pfizer) vaccine in patients treated with anticancer agents. DESIGN, SETTING, AND PARTICIPANTS A prospective observational cohort study was conducted between February 1 and May 31, 2021. Adults treated with anticancer agents who received 2 or 3 doses of vaccine were included; of these, individuals with a weak humoral response 1 month after the second dose received a third injection. INTERVENTIONS Quantitative serologic testing of antibodies specific for SARS-CoV-2 was conducted before vaccination and during follow up. MAIN OUTCOMES AND MEASURES Humoral response was evaluated with a threshold of anti-SARS-CoV-2 spike protein antibody levels at 1000 arbitrary units (AU)/mL to neutralize less-sensitive COVID-19 variants. RESULTS Among 163 patients (median [range] age, 66 [27-89] years, 86 men [53%]) with solid tumors who received 2 or 3 doses of vaccine, 122 individuals (75%) were treated with chemotherapy, 15 with immunotherapy (9%), and 26 with targeted therapies (16%). The proportions of patients with an anti-S immunoglobulin G titer greater than 1000 AU/mL were 15% (22 of 145) at the time of the second vaccination and 65% (92 of 142) 28 days after the second vaccination. Humoral response decreased 3 months after the second dose. Treatment type was associated with humoral response; in particular, time between vaccine and chemotherapy did not interfere with the humoral response. Among 36 patients receiving a third dose of vaccine, a serologic response greater than 1000 AU/mL occurred in 27 individuals (75%). CONCLUSIONS AND RELEVANCE The results of this cohort study appear to support the use of a third vaccine dose among patients with active cancer treatment for solid tumors.

Automated summary

This study aimed to assess the immune humoral response to the BNT162b2 vaccine in patients treated with anticancer agents. The results showed that the majority of patients had a good humoral response 28 days after the second dose of vaccine, but it gradually decreased over time. The study also found that the time between vaccine and chemotherapy did not interfere with the humoral response.