Patients with cancer were found to have an adequate immune response after 2 doses of the SARS-CoV-2 vaccine, although the response was weaker than that of healthy individuals, according to the results of a prospective, single-center cohort study published in JAMA Oncology.

Investigators included adult patients with solid tumors undergoing active intravenous cancer treatment — and had received at least 1 prior dose of anticancer treatment — and who received the second dose of the mRNA-BNT162b2 (Pfizer/BioNTech) vaccine at least 12 days prior to enrollment in the study. Patients were excluded if they had a history of a documented positive COVID-19 infection or symptoms of infection. The control group consisted of Individuals taken from a convenience sample of patients’ family or caregivers who accompanied them to their treatment. All study participants gave blood samples on the day they came in for neoplastic treatment between February and March of 2021. The blood samples were analyzed via microparticle immunoassay for anti-SARS-CoV-2 spike receptor-binding immunoglobulin G (IgG) antibodies using the Abbott architect i2000sr platform, with seropositivity defined as ≥50 AU/mL.

The study population comprised 102 cancer patients, 58 of whom were men, with a median age of 66 years (interquartile range [IQR], 56-72) and 78 healthy controls, 25 of whom were men, with a median age of 62 years (IQR, 49-70). The most common tumor type was gastrointestinal (28%).


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In the cancer patient group, 92 (90%) patients were seropositive for SARS-CoV-2 antispike IgG antibodies vs 100% of individuals in the control group. The median IgG titer level in cancer patients was 1931 AU/mL (IQR, 509-4386), which was significantly lower than the median titer level in the control group (7160 AU/mL [IQR 3129-11,241]; P <.001). Multivariable analysis showed that only treatment with chemotherapy plus immunotherapy was significantly associated with lower IgG titers (B, -3.5; 95% CI, -5.6 to -1.5). Other variables analyzed included age, sex, cancer type, and time elapsed since the second vaccine dose.

Of the 10 seronegative patients, 6 were men and diagnoses included gastrointestinal (n=4), lung (n=2), breast (n=3), and genitourinary (n=1) cancers; 4 patients were receiving chemotherapy plus immunotherapy.

Limitations of the study included the fact that it did not directly evaluate prior COVID-19 illness via prevaccination anti-spike antibody titers or serologic assays for nucleocapsid proteins. The sample size was small, preventing analysis of an association between treatment regimens and titer levels.

“The confidence of patients with cancer in their ability to be effectively vaccinated” may help reduce their avoidance of treatment in medical centers and enrollment in clinical trials for fear of contracting COVID-19, the study authors wrote.

The study authors also noted that this study would support a third booster dose or serology-based vaccine dosing in cancer patients undergoing active treatment, which was recently recommended for the general population in order to improve immunogenicity of the SARS-CoV-2 vaccine.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

Massarweh A, Eliakim-Raz N, Stemmer A, et al. Evaluation of seropositivity following BNT162b2 messenger RNA vaccination for SARS-CoV-2 in patients undergoing treatment for cancer. JAMA Oncol. Published online May 28, 2021. doi:10.1001/jamaoncol.2021.2155