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One vs Two Doses of the BNT162b2 COVID-19 Vaccine in Patients With Cancer: Immunogenicity and Efficacy


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In an interim analysis of a prospective observational study reported in The Lancet Oncology, Monin et al found that a single dose of the BNT162b2 Pfizer–BioNTech COVID-19 vaccine was poorly immunogenic in patients with cancer, with immunogenicity markedly improving at 2 weeks after a second dose given 21 days following the first.

Study Details

The study involved 151 patients with cancer, including 95 with solid cancers and 56 with hematologic cancers, and 54 healthy controls (primarily health-care workers) who were enrolled at 3 London hospitals between December 8, 2020, and February 18, 2021. Participants who were vaccinated between December 8 and 29, 2020, received two 30-μg doses of BNT162b2 21 days apart; those vaccinated after this date received one 30-μg dose with a planned follow-up boost at 12 weeks. The co-primary endpoints were seroconversion to SARS-CoV-2 spike (S) protein in patients with cancer following the first vaccine dose; and the effect of vaccine boosting after 21 days on seroconversion. Follow-up is ongoing for effects of the delayed 12-week vaccine boost.

A total of 17 patients were excluded from analysis after exposure to SARS-CoV-2 was detected by either antibody seroconversion or positive polymerase chain reaction COVID-19 swab test.

In patients with cancer, one dose of the BNT162b2 vaccine yields poor efficacy. Immunogenicity increased significantly in patients with solid cancer within 2 weeks of a vaccine boost at day 21 after the first dose. These data support prioritization of patients with cancer for an early (day 21) second dose of the BNT162b2 vaccine.
— Monin et al

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Up until day 21 after the first vaccine dose, COVID-19 infection was identified in six patients; two patients scheduled to receive the delayed 12-week boost died from COVID-19.

Key Findings

Positive anti-S IgG titers at approximately 21 days following the first vaccine dose were observed in 32 (94%, 95% confidence interval [CI] = 81%–98%) of 34 healthy controls, 21 (38%, 95% CI = 26%–51%) of 56 patients with solid cancers, and 8 (18%, 95% CI = 10%–32%) of 44 patients with hematologic cancers.

A total of 16 healthy controls, 25 patients with solid cancers, and 6 patients with hematologic cancers received a second dose 21 days after the first dose. Among those with available blood samples 2 weeks following the 21-day boost, positive anti-S IgG titers were found in 12 (100%, 95% CI = 76%–100%) of 12 healthy controls, 18 (95%, 95% CI = 75%–99%) of 19 patients with solid cancers, and 3 (60%, 95% CI = 23%–88%) of 5 patients with hematologic cancers. By comparison, among participants who did not receive a boost, 18 (86%, 95% CI = 65%–95%) of 21 healthy controls, 10 (30%, 95% CI = 17%–47%) of 33 patients with solid cancers, and 4 (11%, 95% CI = 4%–25%) of 36 patients with hematologic cancers were antibody seropositive.

Among 180 participants with toxicity data, no toxicities were reported in 75 (54%) of 140 patients with cancer or in 15 (38%) of healthy controls after the first vaccine dose; no toxicities were reported after the second dose in 22 (71%) of 31 patients with cancer or 5 (31%) of 16 healthy controls. Injection site pain within 7 days following the first dose was the most common local reaction, reported in 23 (35%) of 65 patients with cancer and in 12 (48%) of 25 healthy controls. Local and systemic adverse effects after the second dose were reported in 2 (7%) of 31 patients with cancer and 8 (50%) of 16 healthy controls. No vaccine-related deaths were reported.

The investigators concluded, “In patients with cancer, one dose of the BNT162b2 vaccine yields poor efficacy. Immunogenicity increased significantly in patients with solid cancer within 2 weeks of a vaccine boost at day 21 after the first dose. These data support prioritization of patients with cancer for an early (day 21) second dose of the BNT162b2 vaccine.”

Sheeba Irshad, PhD, of the Comprehensive Cancer Centre, School of Cancer & Pharmaceutical Sciences, King’s College London, is the corresponding author for The Lancet Oncology article.

Disclosure: The study was funded by King’s College London, Cancer Research UK, Wellcome Trust, Rosetrees Trust, and Francis Crick Institute. For full disclosures of the study authors, visit thelancet.com.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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