ESMO Congress 2024 | OncologyPRO

Abstract 1354P

Background

To determine the effect of antibiotic therapy within 30 days of initiation of immune checkpoint inhibitors in patients with stage IV non-small cell lung cancer (NSCLC).

Methods

A deidentified database platform, TriNetX, was queried for patients with stage IV NSCLC who received any of Pembrolizumab, Nivolumab, Durvalumab and Atezolizumab and who received antibiotics in a period within 30 days of initiation of ICI therapy; compared to those who didn’t. These patients were 1:1 matched for age, age at index event and sex to resulting in two groups of 893 patients each. The primary end point was overall survival.

Results

1796 patients were included, 893 In each group. All had stage IV disease. The mean age was 71 years (25 – 90 years). 54% were male, 36% were female and 10% had unknown sex. The group with antibiotic use had 657 deaths amongst 893 with a risk % of 73.6% compared to 541 deaths in the no antibiotic use group with a risk % of 60.6%. The risk difference was 13% (8.7 – 17.3) with a risk ratio of 1.21 (1.14-1.30) with a p value of <0.0001. The antibiotic group had a median survival of 236 days, and no antibiotic group had a median survival of 529 days (p value < 0.0001).

Conclusions

The use of antibiotics within a period of 30 days after the initiation of ICI in patients with stage IV NSCLC conferred a poorer outcome. This may be due to the effect of the GI tract and gut microbiome on immunomodulation and efficacy of ICIs which is disrupted by the use of antibiotics. There could be several confounding factors like variations in the burden of the disease, combination therapies with ICI, performance status and comorbidities of the patients that are not accounted for in this database-based study.