Patients with chronic lymphocytic leukemia (CLL) have increased risk for severe COVID-19 disease as well as mortality.
Such patients are likely to have compromised immune systems, making them respond poorly to vaccines, as has been seen in studies involving pneumococcal, hepatitis B, and influenza A and B vaccination.
In order to determine if vaccination against COVID-19 disease will be effective among these patients, researchers performed a study to determine the efficacy of a single COVID-19 vaccine in patients with CLL. They found that the response rate of patients with CLL to vaccination was significantly lower than that of healthy controls, according to the study published in Blood Advances .
The study (NCT04746092) assessed the humoral immune responses to BNT162b2 mRNA COVID-19 (Pfizer) vaccination in adult patients with CLL and compared responses with those obtained in age-matched healthy controls. Patients received two vaccine doses, 21 days apart, and antibody titers were measured 2-3 weeks after administration of the second dose, according to Yair Herishanu, MD, of the Tel-Aviv Sourasky Medical Center, Tel Aviv University, and colleagues.
The researchers found an antibody-mediated response to the BNT162b2 mRNA COVID-19 vaccine in only 66 of 167 (39.5%) of all patients with CLL. The response rate of 52 of these responding patients with CLL to the vaccine was significantly lower than that occurring in 52 age- and sex-matched healthy controls (52% vs. 100%, respectively; adjusted odds ratio, 0.010; 95% confidence interval, 0.001-0.162; P < .001).
Among the patients with CLL, the response rate was highest in those who obtained clinical remission after treatment (79.2%), followed by 55.2% in treatment-naive patients, and it was only 16% in patients under treatment at the time of vaccination.
In patients treated with either BTK inhibitors or venetoclax with and without anti-CD20 antibody, response rates were low (16.0% and 13.6%, respectively). In particular, none of the patients exposed to anti-CD20 antibodies less than 12 months prior to vaccination responded, according to the researchers.
Multivariate analysis showed that the independent predictors of a vaccine response were age (65 years or younger; odds ratio, 3.17; P = .025), sex (women; OR, 3.66; P = .006), lack of active therapy (including treatment naive and previously treated patients; OR 6.59; P < .001), IgG levels 550 mg/dL or greater (OR, 3.70; P = .037), and IgM levels 40mg/dL or greater (OR, 2.92; P = .017).
Within a median follow-up period of 75 days since the first vaccine dose, none of the CLL patients developed COVID-19 infection, the researchers reported.
“Vaccinated patients with CLL should continue to adhere to masking, social distancing, and vaccination of their close contacts should be strongly recommended. Serological tests after the second injection of the COVID-19 vaccine can provide valuable information to the individual patient and perhaps, may be integrated in future clinical decisions,” the researchers concluded.
The study was sponsored by the Tel-Aviv Sourasky Medical Center. The authors reported that they had no conflicts of interest.