THURSDAY, Oct. 6, 2022 (HealthDay News) — For patients with hematologic malignant neoplasms undergoing B cell-targeted therapy and for those with solid malignant neoplasms, antibody levels against the receptor-binding domain (RBD) of the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) increased after receipt of a fourth vaccination, according to a research letter published online Sept. 22 in JAMA Oncology.

Maximilian J. Mair, M.D., from the Medical University of Vienna, and colleagues analyzed variant-specific humoral immunity after active and passive SARS-CoV-2 immunization in patients with hemato-oncologic diseases. Antibody levels against the RBD of the spike protein of SARS-CoV-2 hu-1 and omicron sublineages BA.1 or BA.4 were compared after the third and fourth vaccinations or administration of tixagevimab and cilgavimab in 72 patients with cancer. Seventy-five percent of the patients received a fourth vaccination and 25.0 percent received passive immunization with tixagevimab and cilgavimab.

The researchers found that the median anti-RBD levels increased after versus before the fourth vaccination in patients with hematologic malignant neoplasms undergoing B cell-targeted therapy, especially against omicron BA.1 and BA.4. For patients with other hematologic diseases, no differences were seen in antibody levels. For all investigated variants of concern, including hu-1, BA.1, and BA.4, a pronounced increase in median anti-RBD levels was seen in patients with solid malignant neoplasms after versus before the fourth vaccination.

“Our results suggest that immunization with tixagevimab/cilgavimab does not effectively block the most recently dominant BA.4 variant,” Mair said in a statement.

Several authors disclosed financial ties to the pharmaceutical industry.

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