Do People Receiving Chemotherapy or Immunotherapy Have an Adequate Antibody Response to the COVID-19 Vaccine?

Among solid (organ) cancer patients receiving chemotherapy or immunotherapy, most, but not all, were found after two doses of mRNA-1273 (Moderna) vaccination, without new side effect concerns, to have an immune response at an adequate level.

ESMO 2021 Virtual Congress results presented on day 3 address chemotherapy and immunotherapy in relation to SARS-CoV-2 vaccination, providing important insight into their effects on whether vaccination generates an adequate immune response and on its safety.

This prospective study compared immune response and safety in 4 groups:

• people without cancer,
• people receiving immunotherapy,
• people receiving chemotherapy, and
• patients with solid tumors treated with chemotherapy and concurrent immunotherapy.

Of 791 enrolled participants, 743 were antibody-negative at baseline; patients received two doses of the Moderna vaccine 28 days apart. This vaccine has characteristics very similar to BioNTech. Assessments were completed on day 28 after the second vaccination.

The primary endpoint was the serum IgG antibody response specific to the SARS-CoV-2 virus's spike protein (Spike S1) (>10 binding antibody units (BAU)/mL). An adequate antibody response was achieved by 97.4–100% of participants 28 days after the second vaccination.

Figure. Non-inferior antibody response to the mRNA-1273 vaccine in patients with cancer receiving immunotherapy, chemotherapy or chemo-immunotherapy compared with controls without cancer

After the first vaccination, an adequate response was defined as a threshold of 300 BAU/mL based on the neutralizing capacity of vaccine-induced antibodies. This level was reached after the first vaccination by 66% of people without cancer, 37.1% of patients receiving immunotherapy, 32.5% of those receiving chemotherapy and 33.3% of those receiving chemo-immunotherapy. After the second vaccination, within 28 days, the proportion with an adequate response rose to 99.6% of people without cancer, 93.1% in immunotherapy, 83.8% in chemotherapy and 88.8% in chemo-immunotherapy. Spike protein-specific T-cell responses were detected in 46.8% of inadequate responders.

The authors concluded that a substantial minority — up to approximately 16% — did not have an adequate response, and these patients may need an additional vaccine dose. No new side effects were observed in patients with cancer.

Related topic: COVID Vaccination after the Fourth Wave of the Pandemic – Discussion of the 3rd and 4th Doses

Another important finding was that, in terms of antibody response in people receiving chemotherapy, vaccination on day 1 or day 11 of chemotherapy made no difference.

In conclusion, the main messages from this prospective study are that vaccination against SARS-CoV-2 is safe in patients with cancer and that patients with solid tumors develop a robust immune response similar to that of healthy controls, independently.