Humoral Responses After SARS-CoV-2 mRNA Vaccination and Breakthrough Infection in Cancer Patients

Area of Science:

• Immunology
• Oncology
• Vaccinology

Background:

• Patients with cancer undergoing active therapies often have compromised immune systems, raising concerns about their response to vaccinations.
• Assessing the humoral immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines is crucial for this vulnerable population.

Purpose of the Study:

• To evaluate the magnitude of the antibody response to SARS-CoV-2 mRNA vaccines in cancer patients receiving active treatments.
• To compare the humoral response between immunocompetent individuals and those with hematologic or solid malignancies.

Main Methods:

• Included patients aged 18 years or older with measured SARS-CoV-2 spike antibody (anti-S Ab) levels after two mRNA vaccine doses.
• Excluded patients with prior COVID-19 infection or those on other immunosuppressive therapies.
• Categorized patients into immunocompetent, hematologic malignancy, and solid malignancy groups, analyzing antibody titers and seroconversion rates.

Main Results:

• Immunocompetent patients (96.7%) achieved high anti-S Ab titers (≥500 U/mL), significantly more than those with hematologic (7.7%) or solid (55.1%) malignancies.
• A substantial proportion of patients with hematologic (52.7%) and solid (8.2%) malignancies on cytopenic therapy showed no seroconversion (<0.8 U/mL) after two vaccine doses.
• Two vaccinated patients developed breakthrough COVID-19 infections.

Conclusions:

• Patients with hematologic and solid malignancies receiving chemotherapy or CDK4/6 inhibitors exhibit poor humoral responses to SARS-CoV-2 mRNA vaccines.
• This study confirms suboptimal antibody responses in immunosuppressed individuals, emphasizing the need for careful monitoring.
• Assessing antibody response post-vaccination is vital for managing COVID-19 risk in cancer patients.