Dr. Shaalan Beg highlights practice-changing studies in GI cancers featured at the 2024 ASCO Annual Meeting, including the ESOPEC trial in esophageal adenocarcinoma and durable responses to PD-1 blockade alone in mismatch repair-deficient locally advanced rectal cancer. TRANSCRIPT Geraldine Carroll: Welcome to the ASCO Daily News Podcast. I'm Geraldine Carroll, a reporter for the ASCO Daily News. My guest today is Dr. Shaalan Beg, an adjunct associate professor at UT Southwestern Simmons Comprehensive Cancer Center. Dr. Beg will be discussing practice- changing abstracts and other key advances in GI oncology that were presented at the 2024 ASCO Annual Meeting. His full disclosures are available in the transcript of this episode.  Dr. Beg, thanks for being on the podcast today.  Dr. Shaalan Beg: Thank you for having me. Geraldine Carroll: Let's begin with LBA1, the ESOPEC trial. This was featured in the Plenary Session, and this study compared two treatment strategies for locally advanced esophageal adenocarcinoma that could be treated with surgery. The strategies include the CROSS protocol, which consisted of chemoradiotherapy before surgery, and the FLOT protocol of chemotherapy before and after surgery. Can you tell us about this practice-changing study, Dr. Beg? Dr. Shaalan Beg: Yes. According to this study, perioperative chemotherapy with FLOT was better than neoadjuvant therapy with chemoradiation and carbo-taxol for people with adenocarcinoma of the esophagus. There were 438 patients enrolled on this phase 3 study. R0 resection rates were fairly similar across both groups. The PCR rates were a little higher on the FLOT group. But when you look at the median overall survival difference, 66 months in the FLOT group versus 37 months in the CROSS group, 3-year survival was 57% versus 50% favoring FLOT therapy as well.  So a couple of caveats on this clinical trial, because the first thing to note is that the standard treatment for this disease has evolved because we now don't only give CROSS chemoradiation, we also give immunotherapy after the completion of chemoradiation for this group of patients. And in this study, since it predated that standard of care, patients did not receive immunotherapy. But having said that, the take home for me here is that chemotherapy is better than chemoradiation for this group of patients, recognizing the fact that 1) they only enrolled adenocarcinoma patients, and 2) patients with high T stage were not included. So the folks with high T stage would be those who we would expect would benefit from the radiation aspect. So my take home here is that more chemotherapy is better in the perioperative space. Radiation should be considered for individuals who need more local control. But in general, I think we're going to see us moving more towards chemotherapy-based regimens with FLOT for this group of patients. Geraldine Carroll: Great. So moving on to rectal cancer, in LBA3512, investigators reported durable, complete responses to PD-1 blockade alone in mismatch repair deficient locally advanced rectal cancer. Can you tell us more about the promising durable responses that occurred in this trial?  Dr. Shaalan Beg: On first glance, seeing that immunotherapy has good activity in patients with mismatched repair deficient rectal cancer isn't really headline breaking news anymore. We've known about this activity for this group of patients for many years. Earlier at ASCO, the investigators presented early results of this compound for people receiving six months of dostarlimab therapy for people with mismatched repair deficient, locally advanced rectal cancer, and showed that they had a very high complete response rate. At that time, it generated a lot of interest and there was a lot of curiosity on whether these outcomes will be sustained. We don't know other characteristics of their biologic status and whether this was some sort of reflection of the patients who are selected or not.   So here