Antibody Testing May Decrease Infection Risk in Blood Cancer Survivors

Patients with blood cancer who had frequent tests for a certain type of antibody tended to be less likely to get severe infections compared to those who were not frequently tested for it, according to a study recently published in Blood Advances.

The researchers analyzed data from 3,920 patients with chronic lymphocytic leukemia (CLL) and 13,232 patients with non-Hodgkin lymphoma who were treated between 2010 and 2023. The goal of the study was to see if there was a difference in outcomes depending on the protocol patients underwent regarding immunoglobulin G (IgG; an antibody that is important for fighting off infections) monitoring and replacement.

READ MORE: CLL and Its Treatment Can Heighten Patients’ Risk of Infections

In the CLL group, previous therapies were targeted therapy (30.4%), monoclonal antibody (29.2%) cytotoxic chemotherapy (19.9%), hematopoietic stem cell transplant (replacing damaged stem cells with healthy stem cells from the patient; 5.5%) and CAR-T cell therapy (2%). In the non-Hodgkin lymphoma group, previous therapies included: anti-CD20 monoclonal antibody (38.9%), hematopoietic stem cell transplant (15.2%), and CAR-T cell therapy (6.9%).

In the group of patients with non-Hodgkin lymphoma, 51.2% underwent IgG testing and 4.7% had IgG replacement therapy. In those with CLL, IgG testing and replacement therapy rates were 67% and 6.5%, respectively.

“Our most striking finding is that real-world practice is highly variable. We found that many patients are not tested for IgG deficiency, and IgG [replacement therapy] is often not given despite the development of recurrent infections,” study author Dr. Jacob D. Soumerai said in a press release about the findings.

Soumerai is an assistant professor of medicine at Massachusetts General Hospital Cancer Center and Harvard Medical School. After parsing out the patients who received IgG testing, he and colleagues then identified patients with low (500 milligrams/deciliter) IgG levels as well as the infection rate and associated antimicrobial use at multiple time points.

Study findings showed that increased IgG testing was significantly associated with a lower risk of developing a severe infection. Specifically, patients with CLL had a 92% decreased chance of severe infection, while those with non-Hodgkin lymphoma had an 86% decreased chance.

According to the release, clinical guidelines vary on how frequently patients should undergo IgG testing. There is also a wide discrepancy in testing among clinicians as well.

“This underlines the urgent need to establish clear consensus on best practices for IgG testing and IgG [replacement therapy] use in patients with CLL and NHL to reduce recurrent infections in our patients,” Soumerai said.

Additionally, these findings also underscore the importance for patients with these blood cancers to communicate with their health care team regarding infections that they experience, according to Soumerai.

“Within each disease cohort, patients with three or more IgG tests were more likely to have low IgG detected and also more likely to receive IgG [replacement therapy],” said Soumerai. “These findings suggest that patients known to have low levels of IgG might be more likely to communicate recurrent minor infections to their hematologists, leading to improved IgG [replacement therapy] use.”

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