351. INVESTIGATING THE IMPACT OF INDUCTION CHEMOTHERAPY FOR ESOPHAGEAL ADENOCARCINOMA ON THE GUT MICROBIOME
Niharikaa Aiyar, Jonathan Allen, Akhi Akhter, Thiaine Rispoli, Maria Kulikova, Premalatha Shathasivam, Gavin Wilson, Gail Darling, Bryan Coburn, Jonathan Yeung- Gastroenterology
- General Medicine
Abstract
Background
Esophageal adenocarcinoma (EAC) is a highly heterogeneous cancer with a current five-year survival rate of ~18%. To improve outcomes, understanding factors impacting treatment response is imperative. Gut microbiome signatures are one such factor and have been associated with response to immunotherapy and survival in several solid cancers. Thus, we aim to identify variations in gut microbiome signatures at different stages of treatment and elucidate the link of these signatures to treatment responses and patient outcomes.
Methods
Fecal samples were collected from 50 patients prior to induction and 18 during or post induction and stored at −20 ̊C before extracting DNA using the QIAamp DNA Mini Kit. Extracted DNA was quantified and 16S gene expression was confirmed by qPCR using primers targeting the V3-V4 region of the 16S gene, following which 16S rRNA sequencing was performed.
FastQC, MultiQC and Cut Adapt were used for quality control of sequence data before assembly with vsearch. The resulting data was processed following the deblur pipeline. Taxonomy was assigned using Qiime2 classift-hybrid-vsearch-sklean function. Statistical comparison of diversity was conducted in R.
Results
Species diversity within individual samples, the alpha diversity, showed no significant difference between baseline and post-induction samples. Likewise, the comparison of diversity between samples, the beta diversity, showed no significant clustering on baseline compared to post-induction.
On the genus level, there was no significant statistical difference between the normalized counts of individual genera shared between baseline and post-induction samples.
Conclusion
These preliminary results suggest that induction therapy has minimal impact upon species richness of the gut microbiome when compared to baseline as measured by fecal microbiome. Future directions of this project include examining the gut microbiome at further stages of treatment and investigating the microbiome of the tumour itself.