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Eosinophil count tied to immunotherapy’s efficacy, adverse effects in lung cancer

Lung Cancer
Reuters Health - 08/09/2020 - In patients with advanced non-small-cell lung cancer receiving immune-checkpoint inhibitors (ICIs), baseline peripheral-blood absolute eosinophil count (AEC) is tied to both ICI-related pneumonitis and better clinical outcome, according to researchers in China.

As Dr. Chunxia Su explained in an email to Reuters Health, "Predictive markers of efficacy of immunotherapy are often closely related to the occurrence of adverse reactions."

In a paper in Lung Cancer, Dr. Su of Tongji University School of Medicine, in Shanghai, and colleagues note that treatment with ICIs is accompanied by a wide range of immune-related adverse events (irAEs). Among the most worrisome of these is ICI-pneumonitis.

ICI-pneumonitis presents as the development of respiratory signs and symptoms, including cough, dyspnea and hypoxia, along with the presence of new pulmonary infiltrates on chest CT scans after initiation of ICI treatment.

To help establish risk factors, the researchers retrospectively examined data on 300 of their patients and identified 54 (18%) who had experienced ICI-pneumonitis.

Those with ICI-pneumonitis had a significantly higher level of baseline peripheral-blood AEC than those without the condition. The optimum threshold of baseline peripheral-blood AEC to predict ICI-pneumonitis was 125 million cells/L. The incidence of ICI-pneumonitis was 27.7% in those at or above this value and 9.8% in those with a lower value (P<0.001).

In addition, patients with high AEC had a significantly higher objective response rate (40.9%) than did those with a low AEC (28.8%). This was also true of median progression-free survival (8.93 vs. 5.87 months).

The AEC threshold they found, say the researchers, "might be helpful for risk stratification of ICI-pneumonitis and identification of patients who (would) probably benefit from ICIs-based therapy."

And, added Dr Su, "we found that absolute value of eosinophils can predict immune-related side effects as well as the efficacy of immunotherapy." Further exploration of the mechanism is required "to deal with the side effects without weakening the impact on efficacy."

By David Douglas

SOURCE: https://bit.ly/3gWOiBB Lung Cancer, online August 23, 2020.

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