John L. Marshall, MD


May 23, 2014

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Hey, everyone, this is John Marshall for Medscape. It is the end of May and that means only one thing: ASCO® is just around the corner. The ASCO (American Society of Clinical Oncology) meeting is our annual migration to Chicago where we run around from 6:00 AM until 11:00 PM, say hello to everyone, and frankly do not really learn all that much, but that is another matter altogether. This year, I am not going. I have an important family event. As it is our annual ritual, however, I do want to highlight the presentations that will have the biggest impact on gastrointestinal (GI) cancers. There are a few, particularly in colorectal cancer, that are worth noting.

The big paparazzi moment, a plenary paper, will be a Cancer and Leukemia Group B (CALGB) study presented by Alan Venook,[1] principal investigator of this study, which is on frontline treatment of colon cancer. In this study, patients received either FOLFOX or FOLFIRI and then were randomly assigned to either bevacizumab or cetuximab. At the start of the study, we did not understand about RAS and K-RAS, etc, so the study had to be expanded over time. This will be a big moment for a head-to-head, one biologic class vs another biologic class in frontline colon cancer comparison, so that is a presentation to watch for. The problem is that I do not think we will have the complete RAS testing for that study; we will have only K-RAS, so this may not be the final story even on that.

In the main colon cancer sessions, we will see refinements that will really drill down on the role of oxaliplatin in rectal cancers. I am confused. Some studies say maybe it helps and other studies say it does not help. A couple more studies[2,3] to be presented at ASCO are looking at that -- further studies on this maintenance concept, what is the right recipe in the maintenance window, is it a vascular endothelial growth factor (VEGF) alone, is it VEGF plus a fluoropyrimidine, or is it something else?[4,5] Those will be interesting studies.

Other studies will provide additional refinement of the RAS story; we started with EGFR receptors, then it became K-RAS, and now it is even further RAS testing. Only about 40% of patients with colon cancer are candidates for the EGFR targeted therapy now, but the benefit of these therapies is going up, so we will see further data on that.

One of the more exciting presentations will not be in the mainstream and it will not be clinically applicable right now. This is work by Sabine Tejpar's group[6] as well as a global consensus to define molecular subtypes for colorectal cancer. They have it drilled down to 4 or 5 subtypes. If this holds true, this will really make our work a lot easier -- where we start to divide colon cancer into its groups and treat them differently. This is going to change how we do business in colon cancer for the future. We will have to start sorting patients according to this. That is one issue to look out for in the future in colon cancer; that is from Sabine Tejpar's group.

Some new medicines look promising for other GI cancers and for pancreatic cancer (thank the Lord), so we see some progress there, and again, other refinements in some of the other diseases. But the major breakthrough study, CALGB/SWOG 80405, will be presented in the plenary session. Look for that: a head-to-head VEGF and EGF comparison.

This is John Marshall for Medscape. Have a great time in Chicago. I will be holding down the fort back home.


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