Data suggest that most patients have positive serological results one month after vaccination with either the Moderna or Pfizer vaccine.
Patients with myeloproliferative neoplasms (MPNs) appear to respond well to SARS-CoV-2 vaccination, according to a new report in which patients show high serological and T-cell responses to the two most commonly administered vaccines.
The findings were reported in one letter to the editor of the journal Leukemia. Corresponding author Joan howMD, from Harvard Medical School and colleagues, said that while the SARS-CoV-2 vaccines developed by Moderna and Pfizer have had great success in producing neutralizing antibodies in most adults, the vaccines have produced less robust immunological responses in patients with haematological malignancies. .
Patients with MPNs “are immunocompromised due to impaired congenital and adaptive immunity, increased inflammation, and effects of ongoing treatment,” How and colleagues said. “As a result, patients are at high risk for complications related to SARS-CoV-2 infection.”
Given the novelty of the virus, the researchers wanted to gain a better understanding of how the vaccines worked in humans in the real world with MPNs. They noted that most previous vaccine protection reports in patients with haematological malignancies focused on quantifying anti-spike antibodies. But they said T cell responses are also a key measure of understanding the immune response to vaccination.
“In particular, neutralizing antibody activity is significantly reduced against SARS-CoV-2 variants after vaccination, although T cell responses still appear to be intact,” they wrote. “T cell responses are therefore particularly important in preventing severe COVID-19 caused by new variants such as Omicron.”
The investigators recruited 21 patients with MPN who had baseline blood samples taken, completed vaccination with either the Moderna or Pfizer vaccines, and had another blood sample taken one month after vaccination. A further seven patients were included in the analysis despite having only one blood sample after vaccination and not one sample before vaccination. The authors used data from 26 vaccinated patients with no history of active malignancy as their control group. At baseline, four of the 21 MPN patients had positive serological tests for SARS-CoV-2, and 3 patients had a known history of infection.
In both MPN groups (21 patients plus the additional seven patients), all but one vaccine recipient had evidence of positive serology one month after vaccination. The only patient who did not do so was given ruxolitinib (Jakafi). Similarly, 25 of the 26 patients in the control group had positive serology after one month.
“In the four MPN patients who had positive baseline serology, post-vaccination concentrations appeared to be similar to those of MPN patients without SARS-CoV-2 exposure,” the authors said.
How and colleagues also used two interferon γ release assays to assess T cell responses one month after vaccination.
On one of the assays, the ELISpot assay, positive responses of more than 90% were reported in both the MPN and control groups. However, investigators also found that patients with MPNs tended to have lower anti-Spike immunoglobulin G concentrations, “which may indicate a less robust serological response,” they said.
In addition, the authors said that there appeared to be a signal for lower immunological responses in T-cell assays of patients with myelofibrosis, although the authors noted that the sample size was small as only eight patients with myelofibrosis were included in the analysis. They added that age, but no other variables, appeared to have an effect on T cell response.
How and colleagues said there were other subtle differences between the two groups that may warrant further investigation. They concluded by noting that their samples do not necessarily reflect actual infection rates.
“Prospective studies with endpoints for clinical infection would be needed to understand how immune responses to vaccines translate to the reduction of COVID-19 cases,” they said.