The study covered in this summary was published on medRxiv.org as a preprint and has not yet been peer reviewed.
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).
Certain treatments, such as venetoclax-based regimens, appeared to weaken the efficacy of COVID-19 vaccines.
Why This Matters
COVID-19 vaccine efficacy and the effects anticancer treatments may have on that efficacy are not fully understood for people with blood cancers.
Understanding factors influencing vaccine effectiveness in this patient population can help guide management decisions.
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%).
Patients were receiving or had recently completed systemic anticancer therapy.
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.
Vaccine doses were administered 8 to 12 weeks apart, in keeping with UK guidelines; 72% of patients received the Pfizer shot.
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).
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.
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.
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.
Patients with acute leukemia can generate robust serologic responses to natural infection but not always to vaccination.
It's not known whether the weaker vaccine response in ALL translates to less protection.
No study limitations were reported.
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: firstname.lastname@example.org.
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Cite this: M. Alexander Otto. COVID Vaccine Response Varies by Blood Cancer Type, Treatment - Medscape - Apr 20, 2022.