A review of mRNA COVID-19 vaccines in patients with chronic lymphocytic leukemia

This review aimed to assess the strength of previous evidence and to better understand the current role of SARS-CoV-2 vaccination in patients with chronic lymphocytic leukemia (CLL). 

This review concluded that there is an overall lower seroconversion rate for SARS-CoV-2 vaccination in these patients as compared with the general population. This review also concluded that CLL treatment worsened the defective response to vaccination observed in these patients.

Since the COVID-19 pandemic, there is a lot of debate regarding the effectiveness and safety of mRNA vaccines, particularly in people with cancer. In immunocompetent (people with a normal immune response) persons, the mRNA vaccines BNT162b2 and mRNA-1273 have been shown to be safe and effective against SARS-CoV-2 infection. 

However, patients with B-cell blood cancers, such as chronic lymphocytic leukemia (CLL) commonly fail to develop a strong antibody response following vaccination. This is thought to be due to the defects in immunity in CLL. CLL treatment may also worsen immune system dysfunction. Patients with CLL are considered to have a lower response to SARS-CoV-2 mRNA vaccines. However, more information is needed regarding the effectiveness of SARS-CoV-2 vaccines in patients with CLL.  

This study review 13 previous studies in which 2082 patients with CLL participated. The studies reviewed the seroconversion rate (rate of antibodies after vaccination) in patients with CLL after two doses of SARS-CoV-2 vaccination.  

The seroconversion rate in the general population of patients CLL was 52%. 

Treatment status was available for 71.1% of patients. Among them, 35.9% were treatment naïve (did not receive any CLL treatments). The seroconversion rate for the treatment naïve group was 73%.  

64% of patients were receiving treatment at the time of anti-COVID-19 vaccination. Patients were assigned to different groups, according to which CLL treatments they were receiving. Group 1 included patients who had been given an anti-CD20 monoclonal antibody such as rituximab (Rituxan) at any time before vaccination. Group 2 included patients vaccinated within 12 months from the last infusion of anti-CD20 antibody. Group 3 included patients on therapy with Bruton Tyrosine kinase inhibitors (BTKi) such as ibrutinib (Imbruvica). Group 4 was patients on therapy with venetoclax (Venclexta).

The seroconversion rate for group 1 was 41%. The seroconversion rate for group 2 was 4%. The seroconversion rate for group 3 was 29% and for group 4 was 32%.  

In CLL patients with asymptomatic disease who did not require therapy, almost two-thirds experienced an optimal response to vaccination.  

This review concluded that there is an overall lower seroconversion rate for SARS-CoV-2 vaccination in patients with CLL as compared with the general population. This review also concluded that CLL treatment worsened the lower response to vaccination observed in these patients.  

The studies analyzed were very different. The overall number of participants was very small.