IgG tests reduce infections in CLL or NHL hypogammaglobulinaemia

Blood cancers

By Michael Woodhead

4 Jul 2024

Blood cancer patients with hypogammaglobulinaemia have fewer infections if they receive immunoglobulin replacement therapy (IgRT) guided by tests for IgG deficiency, new research findings suggest.

A US study of more than 17,000 patients with chronic lymphocytic leukaemia (CLL) and non-Hodgkin lymphomas (NHLs) showed that those who received frequent tests for IgG were more likely to have hypogammaglobulinaemia detected and treated, and less likely to experience severe infections compared with those who didn’t.

The findings, published in Blood Advances (link here) showed that patients who received IgRT also had higher blood levels of IgG following the administration of IgRT and required fewer antimicrobial medications.

However the results also showed that patterns of IgG testing and IgRT treatment were highly variable, with only half of patients undergoing such testing.

In the study led by Dr Jacob Soumerai, a haematologist at Massachusetts General Hospital Cancer Center, researchers analysed data for 17,192 adult patients treated for CLL (3,920) or NHL (13,232) between 2010 and 2023.

With a median follow up of four and a half years, 51.2% of patients with NHL underwent IgG testing and 4.7% received IgRT; among those with CLL, 67% received IgG testing and 6.5% were treated with IgRT.

In the CLL patient cohort, IgRT initiation was associated with significantly lower odds of infection and severe infection at three months (Odds Ratio [95% CI]=0.52 [0.38–0.71],  P<.0001).

Similarly, In NHL patients, IgRT initiation was associated with significantly lower odds of infection and severe infection at three months (OR [95% CI]= 0.60 [0.49–0.75], P<.0001).

The odds of sinopulmonary and skin or soft tissue infections, infection-associated antimicrobial use, and severe infection-associated antimicrobial use were also lower in the three months after IgRT initiation than before. The findings were consistent at the six and 12-month follow-up time points.

The analysis also showed that increased frequency of IgG testing was associated with a significantly lower likelihood of severe infection.

“Our most striking finding is that real-world practice is highly variable. We found that many patients are not tested for IgG deficiency, and IgRT is often not given despite the development of recurrent infections,” said Dr 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 IgRT,” he added.

“These findings suggest that patients known to have low levels of IgG might be more likely to communicate recurrent minor infections to their haematologists, leading to improved IgRT use.”

Dr Soumerai noted that in both patient cohorts, the number of IgG tests per patient spanned a wide range, with many patients not receiving any IgG testing during the study period.

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

The study was funded by Takeda Pharmaceuticals.

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