Immune response against the SARS-CoV-2 spike protein in cancer patients after COVID-19 vaccination during the Omicron wave: a prospective study.

BACKGROUND

Cancer patients often have weakened immune systems, resulting in a lower response to vaccines, especially those receiving immunosuppressive oncological treatment (OT). We aimed to assess the impact of OT on the humoral and T-cell response to the B.1 lineage and Omicron variant following COVID-19 vaccination in patients with solid and hematological neoplasms.

METHODS

We conducted a prospective study on cancer patients, stratified into OT and non-OT groups, who received a two-dose series of the COVID-19 mRNA vaccine and a booster six months later. The outcomes measured were the humoral (anti-SARS-CoV-2 S IgG titers and ACE2-S interaction inhibition capacity) and cellular (SARS-CoV-2 S-specific T-cell spots per million PBMCs) responses against the B.1 lineage and Omicron variant. These responses were evaluated four weeks after the second dose (n = 98) and eight weeks after the booster dose (n = 71).

RESULTS

The humoral response after the second vaccine dose against the B.1 lineage and Omicron variant was significantly weaker in the OT group compared to the non-OT group (q-value<0.05). A booster dose of the mRNA-1273 vaccine significantly improved the humoral response in the OT group, making it comparable to the non-OT group. The mRNA-1273 vaccine, designed for the original Wuhan strain, elicited a weaker humoral response against the Omicron variant compared to the B.1 lineage, regardless of oncological treatment or vaccine dose. In contrast, T-cell responses against SARS-CoV-2, including the Omicron variant, were already present after the second vaccine dose and were not significantly affected by oncological treatments.

CONCLUSIONS

Cancer patients, particularly those receiving immunosuppressive oncological treatments, should require booster doses and adapted COVID-19 vaccines for new SARS-CoV-2 variants like Omicron. Future studies should evaluate the durability of the immune response and the efficacy of individualized regimens.