Single dose of BNT162b2 mRNA vaccine against SARS-CoV2 induces neutralizing antibody and polyfunctional T-cell responses in patients with CML

Harrington, P.; Doores, K.; Radia, D.; O'Reilly, A.; Lam, H. P. J.; Seow, J.; Graham, C.; Lechmere, T.; McLornan, D.; Dillon, R.; Shanmugharaj, Y.; Espehana, A.; Woodley, C.; Saunders, J.; Curto-Garcia, N.; O'Sullivan, J.; Kordasti, S.; Malim, M. H.; Harrison, C.; de Lavallade, H.

Patients receiving targeted cancer treatments such as tyrosine kinase inhibitors (TKIs) have been classified in the clinically extremely vulnerable group to develop severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), including patients with Chronic Myeloid Leukaemia (CML) taking TKIs. In addition, concerns that immunocompromised individuals with solid and haematological malignancies may not mount an adequate immune response to a single dose of SARS-CoV-2 BNT162b2 (Pfizer- BioNTech) vaccine have been raised. We evaluated humoral and cellular immune responses after a first injection of BNT162b2 vaccine in 16 CML patients. Seroconversion and cellular immune response prior and after vaccination were assessed. By day 21 post-vaccination, anti-Spike IgG were detected in 14/16 (87.5%) of CML patients and all developed a neutralizing antibody response (ID50>50), including medium (ID50 of 200-500) or high (501-2000) neutralising antibodies titres in 9/16 (56.25%) patients. T cell response was seen in 14/15 (93.3%) evaluable patients, with polyfunctional responses seen in 12/15 (80%) patients (polyfunctional CD4+ response 9/15, polyfunctional CD8+ T cell response 9/15). These data demonstrate the immunogenicity of a single dose of SARS-CoV-2 BNT162b2 vaccine in most CML patients with both neutralizing antibodies and polyfunctional T-cell responses seen, in contrast to patients with solid tumour or lymphoid haematological malignancies.