The following article features coverage from the IASLC North America Conference on Lung Cancer 2019 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

The composition of the gut microbiome — the population of microorganisms in the gastrointestinal tract that is increasingly thought to play complex and wide-ranging roles in human health — is different in patients with lung cancer who are treated with immunotherapy compared with healthy people. According to data presented at the International Association for the Study of Lung Cancer (IASLC) 2019 North America Conference on Lung Cancer (NACLC 2019) in Chicago, Illinois, patients with lung cancer had significantly different microbiome composition compared with healthy subjects.

In the study, which was led by Jun Zhang, MD, of the University of Iowa Hospitals and Clinics in Iowa City, researchers took swabs of patients’ noses and mouths and stool samples to study their microbiome composition. Sixteen patients with lung cancer who had been previously treated with various anti-PD-1/PD-L1 immunotherapy agents including pembrolizumab, nivolumab, atezolizumab, and durvalumab, both with and without chemotherapy, were included in the study. The researchers compared their microbiota to that of 8 healthy subjects.

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“[Lung cancer] patients exhibited drastically different baseline microbiota composition at both the phylum level, including dramatic increases in Firmicutes, Actinobacteria and Verrucomicrobia, and significant decreases in Bacteroidetes, Proteobacteria and Cyanobacteria.” the authors wrote. This included a “clear inversion of Firmicutes/Bacteroidetes ratio between [healthy subjects] and [lung cancer] patients.” 

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The Firmicutes and Bacteroidetes are two phyla of bacteria that together make up the vast majority of microorganisms in the gut microbiome, and increased or inverted ratios have been previously linked to various disease profiles. 

Interestingly, patients with lung cancer who reported immunotherapy-related toxicities were found to have at baseline markedly more Anaerostipes and Eggerthella and fewer Lachnospira compared with other lung cancer patients who did not report treatment-related toxicity.

“Our project marks an important first step in a long-term study that could shed new light on the microbiome’s influence on immunotherapy treatment outcomes,” the authors concluded.

Read more of Cancer Therapy Advisor‘s coverage of the IASLC NACLC 2019 meeting by visiting the conference page.


  1. Chau J, Yadav M, Furqan M, et al. Analysis of patient microbiome and its correlation to immunotherapy response and toxicity in lung cancer. Presented at: International Association for the Study of Lung Cancer (IASLC) 2019 North America Conference on Lung Cancer (NACLC 2019); October 10-12, 2019: Chicago, Illinois. Abstract OA03.04