Patients with tumors had low seropositivity rates after one vaccine dose but high rates after both doses.

  • Major Finding: Patients with tumors had low seropositivity rates after one vaccine dose but high rates after both doses.

  • Concept: Age, sex, and disease stage did not appear to affect seroconversion rates in patients with cancer.

  • Impact: BNT162b2 seems effective in patients with cancer but may require two doses to provide protection.

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Some recent studies have concluded that cancer is a risk factor for severe or fatal COVID-19, and patients with cancer have been defined by many organizations as comprising a high-risk group to be prioritized for vaccination. Several SARS-CoV-2 vaccines have now shown safety and efficacy in phase III clinical trials; however, these studies did not assess the impact of cancer or anticancer treatment on these outcomes. To address this, Goshen-Lago and colleagues conducted a cohort study of the two-dose Pfizer–BioNTech SARS-CoV-2 mRNA vaccine (BNT162b2) enrolling 232 patients with solid tumors undergoing active anticancer treatment along with 261 healthcare workers, who served as control participants. Following the first vaccine dose, 29% of patients with cancer were seropositive for SARS-CoV-2 IgG, whereas 84% of control participants were seropositive at the same timepoint. Age was a factor affecting seropositivity after the first dose in control participants, with those under age 60 having a seropositivity rate of 94% compared with 80% for those aged 60 or older, but it was not a major factor among patients with cancer. Along with age, sex and disease stage were not found to be correlated with seropositivity after vaccination. Interestingly, IgG titers among those who were seropositive after the first dose did not differ between patients with cancer and control participants. Importantly, after the second vaccine dose, 86% of patients with cancer were seropositive, nearly reaching the seropositivity rate in the control participant group. The safety and tolerability profile for the vaccine was favorable in both groups, and adverse events (mainly injection site pain) were as expected based on previous studies. In summary, this work demonstrates that patients with solid tumors seroconvert following administration of the recommended two doses of the BNT162b2 vaccine despite having lower rates of seropositivity than control participants after a single dose; additionally, the vaccine appeared to be safe in this vulnerable group. Further research to determine whether these findings also apply to hematologic malignancies is warranted.

Goshen-Lago T, Waldhorn I, Holland R, Szwarcwort-Cohen M, Reiner-Benaim A, Shachor-Meyouhas Y, et al. Serologic status and toxic effects of the SARS-CoV-2 BNT162b2 vaccine in patients undergoing treatment for cancer. JAMA Oncol 2021 Jul 8 [Epub ahead of print].

Note:Research Watch is written by Cancer Discovery editorial staff. Readers are encouraged to consult the original articles for full details. For more Research Watch, visit Cancer Discovery online at http://cancerdiscovery.aacrjournals.org/CDNews.