Immune Response to COVID-19 Infection and Vaccination in Patients With CML

Take-aways

• Recent research suggests that patients with chronic myeloid leukemia (CML) experience milder COVID-19 infection than patients with other hematologic malignancies.
• Seropositivity and persistence of antibodies after COVID-19 infection and vaccination in patients with CML was similar to rates observed within the general population.
• Most seropositive patients with CML experienced mild COVID-19 symptoms or were asymptomatic.

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In a letter to the editor of Leukemia & Lymphoma, researchers led by Simone Claudiani, MD, of Imperial College London in the UK, shared additional data on the immune response of patients with chronic myeloid leukemia (CML) to COVID-19 infection and anti-SARS-CoV-2 vaccines.

Immune impairment associated with certain hematologic malignancies and their treatments is believed to be responsible for more severe COVID-19 infection and lower response rate to vaccination. However, recent studies suggest that COVID-19 infection is milder in patients with CML compared with other blood cancers. Additionally, patients with CML who are treated with tyrosine kinase inhibitors (TKIs) may mount early immune response after a single COVID-19 vaccine dose.

Dr. Claudiani and colleagues determined the seroprevalence of SARS-CoV-2 in patients with CML who had not yet been immunized against COVID-19 between June 2020 and February 2021. The investigators also monitored the persistence of seropositivity prior to and following the administration of vaccines. They performed a total of 481 serological tests on 312 patients with CML over 9 months.

At the end of July 2020, the cumulative SARS-CoV-2 antibody prevalence in this population was similar to that observed in London’s general population, at 10.7%. Among 30 seropositive patients, 18 experienced mild symptoms and 12 were asymptomatic. In 33 seropositive patients who received COVID-19 vaccines, binding ratio values increased and seropositivity persisted at last follow-up.

According to these findings, natural anti-SARS-CoV-2 receptor binding domain antibodies can persist for up to 8 to 12 months after COVID-19 infection in patients with CML—similar to what is observed within the general population. The researchers also found evidence of seropositivity up to 3 to 6 months following the second vaccine dose in previously infected patients.

“Our data suggest that CML and treatment with TKI do not affect the risk of SARS-CoV-2 infection, the severity of symptoms nor the ability to mount durable antibody responses,” the authors concluded. “However, robust evidence is still lacking on whether the same conclusions might be applied also to CML patients in advanced disease stages or worse response status.”

Reference

Claudiani S, Parker EL, Milojkovic D, et al. Long-term persistence of natural anti-SARS-CoV-2 antibodies and mild impact of SARS-CoV-2 infection in CML patients: results from a seroprevalence study. Leuk Lymphoma. 2022 Jan 24;1-4.