The study covered in this summary was published on medRxiv.org as a preprint and has not yet been peer reviewed.
Key Takeaways
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The seropositivity rate after a second COVID-19 vaccine dose was 95% among patients with acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (HR-MDS), compared with 79% among patients with acute lymphocytic leukemia (ALL).
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Certain treatments, such as venetoclax-based regimens, appeared to weaken the efficacy of COVID-19 vaccines.
Why This Matters
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COVID-19 vaccine efficacy and the effects anticancer treatments may have on that efficacy are not fully understood for people with blood cancers.
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Understanding factors influencing vaccine effectiveness in this patient population can help guide management decisions.
Study Design
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Investigators assessed antibody responses to two doses of the Pfizer or AstraZeneca vaccine in 53 patients with either ALL (26%), AML (62%), or HR-MDS (11%).
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Patients were receiving or had recently completed systemic anticancer therapy.
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Almost 40% of patients received intensive chemotherapy; 37.7% received venetoclax-combination therapy, 16.9% received nonintensive chemotherapy, and 5.6% received B-cell directed immunotherapy.
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Vaccine doses were administered 8 to 12 weeks apart, in keeping with UK guidelines; 72% of patients received the Pfizer shot.
Key Results
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Among patients with AML or HR-MDS, seroconversion rates and median anti-S antibody titers were higher than among patients with ALL (median, 291 U/mL, vs 5.06 U/mL).
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Patients with AML or HR-MDS also showed significant increases in anti-S titers with two vaccine doses, which was not seen among those with ALL.
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There was no difference in serologic response in patients receiving intensive or nonintensive chemotherapy, but titers were significantly reduced in patients with AML or HR-MDS who received venetoclax-based regimens compared to other therapies.
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Patients with ALL who underwent intensive chemotherapy displayed almost uniformly low antibody titers (<10U/mL) after two vaccine doses, regardless of additional B-cell therapy.
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Patients with acute leukemia can generate robust serologic responses to natural infection but not always to vaccination.
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It’s not known whether the weaker vaccine response in ALL translates to less protection.
Limitations
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No study limitations were reported.
Disclosures
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The authors have disclosed no relevant financial relationships.
This is a summary of a preprint research study, “Antibody Responses to SARS-CoV-2 Vaccination in Patients With Acute Leukaemia and High Risk MDS on Active Anti-Cancer Therapies,” led by W. Y. Chan of University College London. The study has not been peer reviewed. The full text can be found at medRxiv.org.
M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who has worked for several major news outlets before joining Medscape and also an MIT Knight Science Journalism fellow. Email: [email protected].
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