Blood cancers

Patients with chronic myeloid cancers may not be protected by COVID-19 vaccines

Haematologists in the UK have demonstrated impaired antibody response to COVID-19 vaccination in patients with chronic myeloid neoplasms.

Oxford University researchers measured anti-SARS-Cov2 IgG spike (S) antibody levels in 60 patients, more than two weeks following a single dose of either Pfizer (BNT162b2) or the AstraZeneca-Oxford (AZD1222) vaccines.

The study published in the British Journal of Haematology, comprised patients with CML, essential thrombocythemia, polycythaemia vera, myelofibrosis (MF) and MDS.

Compared to seroconversion rates of 98% for Pfizer and 92% for AstraZeneca in 232 health care workers >60 years, seroconversion in chronic myeloid blood cancer patients was a low 58%.

“The median anti-S antibody titre was also significantly lower (630 [IQR 284-1328] vs. 75 [IQR 19-328]; P<0.0001),” the study authors led by Dr Omina Chodhury said.

“When split into disease subgroups, seroconversion was highest in patients with CML (75%), and observed in 5/6 (83%) of CML patients receiving imatinib.”

“We observed here reasonably high seroconversion rates following a single vaccine dose in patients with CML and in patients with MPN patients receiving interferon, but humoral responses in certain MPN and MDS patients, especially those in patients receiving ruxolitinib and hydroxycarbamide, were found to be substantially impaired as compared to healthy adults of a similar age group.”

The researchers said the poor seroconversion rates in a group of patients with chronic blood cancers, including those who are not on cytoreductive treatments, those who are in complete haematological remission or major molecular response, suggests “a clear need for detailed study and careful interrogation of COVID-19 vaccination regimens in potentially vulnerable patient groups.”

“While it is expected that a higher proportion of patients will respond following booster vaccine doses, the suboptimal responses observed here to the 1st vaccine dose highlights an unexpected and potentially important immunocompromise in this patient group, which will be informative for planning our ongoing response to this evolving pandemic.”

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