Abstract 238P
Background
Gut microbiota can become a prognostic or even predictive factor for response to aPD1 treatment in patients (pts) with different cancers.To describe the gut microbiota in pts with locally advanced cutaneous melanoma (CM), gastric cancer (GC), and esophageal squamous cell carcinoma (ESCC).
Methods
The study included adult pts with histologically proven GC, ESCC and locally advanced CM. All patients have no evidence of intestinal infection and no antibiotic use within 28 days prior to study entry. The quantitative and qualitative composition of microorganisms of 136 taxonomic groups were evaluated. Species identification of microbial isolates was obtained by MALDI-TOF and MALDI Biotyper v.3.0 software. Shannon's (H) diversity index was used to quantity the species diversity and uniformity of distribution.
Results
Between Jan 2020 – 2022 60 pts (Table) were enrolled and 129 species of 17 taxonomic group were isolated. Table: 238P
| CM (n=20) | GC (n=21) | ESCC (n=19) | |
| Sex, male | 45% | 62% | 73,7% |
| Age, mean | 63 | 63 | 68 |
| Stage at study entry | |||
| in situ | 2 (10,5%) | ||
| I | 2 (9,5%) | 1 (5,3%) | |
| II | 13 (65,0%) | 5 (23,8%) | 7 (36,8%) |
| III | 6 (30,0%) | 11 (52,4%) | 7 (36,8%) |
| IV | 1 (5,0%) | 3 (14,3%) | 2 (10,5%) |
No significant differences in bacterial taxonomic subunits' diversity were found (H index was 1.04 [95%CI from 0.76 to 1.13], 0.97 [95%CI from 0.73 to 1.21], and 1.11 [95%CI from 0.85 to 1.37] for CM, GC, and ESCC respectively (p=0.731). All patients exhibited an imbalance between anaerobic and aerobic microbiota. Specifically, reductions in Bifidobacteria spp. and Lactobacillius spp. were significant. Notably, normal microbiota and E.coli levels decreased (<10ˆ6 per 1 g feces) in some patients, whereas E.coli levels increased (>10ˆ9 per 1 g feces) in 34.9% of subjects. Lactose-negative E.coli was higher in GC (21.7%), ESCC (15.0%), with none in CM. Additionally, K. pneumoniae and others were notably elevated in GC (52.2%), ESCC (40.0%), and CM (25.0%). GC showed the highest abundance indices with low species diversity.
Conclusions
Further research is needed to precisely analyze the intestinal microbiota's composition and activity using molecular methods, aiming to explore its relationship with cancer treatment efficacy.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.