COMMENTARY

Highlights From ASCO GI: Data That Will 'Advance Care'

Mark A. Lewis, MD

Disclosures

February 01, 2021

This transcript has been edited for clarity.

Hello. This is Dr Mark Lewis, coming to you the weekend after the 2021 American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium. Once again, we were unable to meet in person due to the understandable travel restrictions imposed by the pandemic. Hopefully, next year we will be back together with our colleagues. But for now, the most important thing — and this is always true — is the findings that are going to advance care for our patients who so desperately need them.

I saw several themes in this year's meeting. First of all, I think fibroblast growth factor receptor (FGFR) is emerging as a pan-genomic target in GI cancers. We saw very exciting data about another FGFR inhibitor, infigratinib, in biliary cancer and evidence that FGFR inhibition might hold promise in gastroesophageal junction cancers.

Second, I think immunotherapy continues to move forward in the lines of therapy for several different tumor types. There was a recent editorial by Dr Grothey in The New England Journal of Medicine addressing the role of pembrolizumab after the findings of KEYNOTE-177 in microsatellite-instability-high metastatic colorectal cancer. He made a fairly compelling argument for its promise to perhaps spare patients the burden of chemotherapy altogether. On the other hand, there is a pretty steep plunge in the pembrolizumab arm of KEYNOTE-177 that suggests that at least some patients will still need chemotherapy upfront. Selecting who needs chemotherapy vs immunotherapy remains to be seen, and the sequencing remains a matter of great debate.

Interesting data were presented regarding our understanding of the microbiome as it pertains to who will and won't respond best to immunotherapy. This is an exciting field and we are still very nascent in our understanding of the interplay between the gut microbiome, innate immune response, and then candidacy to exogenous stimulation of the immune system by drugs like pembrolizumab, nivolumab, and ipilimumab. Stay tuned on that.

Finally, I have been burdened my entire career with the ethical dilemma of adjuvant chemotherapy. I liken it to the trolley problem, whereby you have the opportunity to pull a lever by which you know that you will save multiple lives but will possibly hurt or take one life. I know it sounds dramatic, but I really think of adjuvant chemotherapy that way. We know that we are treating some people appropriately but are risking overtreatment and potentially harm. Circulating tumor DNA (ctDNA) holds some promise, at least in the adjuvant colon cancer space, to help us better select who will benefit most, if at all, from adjuvant chemotherapy. There is some very interesting work using a ctDNA assay from our colleagues in Denmark, looking at stage I-III colon cancer patients. While we have not yet proven that it is necessarily predictive of benefit (although it's looking like it might be), it seemed to demonstrate a very strong prediction of recurrence-free survival and certainly outclassed carcinoembryonic antigen in that particular setting. Stay tuned for ctDNA as a means for better selecting who will and won't benefit from adjuvant chemotherapy. Hopefully, the trolley problem will disappear.

For now, this is Mark Lewis, signing off for Medscape. Take care.

Mark A. Lewis, MD, is director of gastrointestinal oncology at Intermountain Healthcare in Salt Lake City, Utah. He has an interest in neuroendocrine tumors, hereditary cancer syndromes, and patient-physician communication.

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