The immunogenicity and safety of the BNT162b2 (Pfizer-BioNTech COVID-19) vaccine against SARS-CoV-2 were recently evaluated in an interim analysis of a study including patients with cancer. A single dose of the vaccine showed reduced efficacy in these patients relative to healthy control group participants, but a second vaccine dose administered 21 days after the first dose provided increased immunogenicity. The study results were reported in Lancet Oncology.
“To the best of our knowledge, this is the first report of the safety and immunogenicity of any COVID-19 vaccine in immunocompromised patient populations, specifically those with an active cancer diagnosis,” the study investigators explained in their report.
Patients with cancer and healthy persons were recruited at hospitals in London, UK, from December 8, 2020, to February 18, 2021, to receive the BNT162b2 vaccine at 30 μg per dose in this study. For some participants, vaccinations were given with a second dose administered on day 21 after the first dose, while another group instead received the second vaccine dose 12 weeks after the first dose. Immunogenicity analyses occur at multiple time points throughout this ongoing prospective study, with suspected SARS-CoV-2-exposed participants excluded from analysis.
Study participants included 151 patients with cancer, with solid cancer in 95 participants and hematologic cancer in 56, and 54 healthy control group participants. Immunogenicity analysis of evaluable participants showed positivity for IgG antibodies to SARS-CoV-2 spike protein at week 3 after the first vaccine dose in 94% (32/34) of healthy control group participants, 38% (21/56) of patients with solid cancer, and 18% (8/44) of patients with hematologic cancer.
Among the participants who received a second vaccine dose on day 21, when assessed 2 weeks after this day-21 dose, the rates of IgG seropositivity were 100% (12/12) of healthy control group participants, 95% (18/19) of patients with solid cancer, and 60% (3/5) of those with hematologic cancer. At the same time point, seropositivity rates among participants who did not receive a day-21 vaccine dose were 86% (18/21), 30% (10/33), and 11% (4/36), respectively.
The vaccine was reportedly well tolerated. Evaluable patients with cancer reported no toxicities at a rate of 54% after the first dose and 71% after the second dose, compared with rates of 38% and 31%, respectively, in the healthy control group.
“In sum, a single dose of 30 μg BNT162b2 failed to induce seroconversion in most patients with cancer,” the study investigators wrote in their report. They noted a strong boosting effect of the second vaccine dose on day 21 in patients with solid cancer and indicated that the boosting effect for patients with hematologic cancers will be evaluated with continued follow-up.
Monin L, Laing AG, Muñoz-Ruiz M, et al. Safety and immunogenicity of one versus two doses of the COVID-19 vaccine BNT162b2 for patients with cancer: interim analysis of a prospective observational study. Lancet Oncol. Published online April 27, 2021. doi:10.1016/S1470-2045(21)00213-8