Neutralising antibody titers and COVID outcomes in cancer patients

Abstract

Background: Cancer patients are at high risk of severe COVID infection and recommended at least three doses of SARS-CoV2 mRNA vaccines. Various anti-neoplastic treatments may affect long-term vaccine immunogenicity. Methods: Patients with solid or haematological cancer were recruited from two Singapore hospitals between July 2021 and March 2022. GenScript cPASS surrogate virus neutralisation assays measured antibody responses, which were correlated with clinical outcomes obtained from medical records and national mandatory-reporting databases. Results: In total, 273 patients were recruited (40 with haematological malignancies and the rest solid tumours). Two-hundred and four patients (74.7%) were receiving active cancer therapy: 98 (35.9%) receiving systemic chemotherapy and the rest targeted or immunotherapy. All patients were seronegative at baseline. After receiving one, two and three doses of SARS-CoV-2-mRNA vaccination, seroconversion rate was 35.2%, 79.4% and 92.4% respectively. After three doses, patients on active treatment for haematological malignancies had lower antibodies (57.3%±46.2) as compared to patients on immunotherapy (94.1%±9.56, p<0.05) and chemotherapy (92.8%±18.1, p<0.05). SARS-CoV-2 infection was reported in 77 (28.2%) patients of which 18 were severe. Conclusion: This study demonstrates high immunogenicity of three doses of vaccines and protection against severe infection in cancer patients.