Dr. Praveen Vikas, Dr. Tyler Johnson, and Dr. Russell Broaddus present the ASCO endorsement of the Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: Guideline From the College of American Pathologists in Collaboration With the Association for Molecular Pathology and Fight Colorectal Cancer. They discuss key evidence-based recommendations, focusing on the appropriate modality of testing (immunohistochemistry, polymerase chain reaction, or next generation sequencing) across multiple cancer types. Additionally, they cover the ASCO endorsement process, points of emphasis raised by the ASCO expert panel, and implications for clinicians and patients. Read the full guideline endorsement, Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: ASCO Endorsement of CAP Guideline at www.asco.org/molecular-testing-and-biomarkers-guidelines.   TRANSCRIPT Brittany Harvey: Hello, and welcome, to the ASCO Guidelines podcast; one of ASCO's podcasts, delivering timely information to keep you up to date on the latest changes, challenges, and advances in oncology. You can find all the shows, including this one, at: asco.org/podcasts. My name is Brittany Harvey, and today, I'm interviewing Dr. Praveen Vikas from the University of Iowa, Dr. Tyler Johnson from Stanford University, and Dr. Russell Broaddus from the University of North Carolina; authors on, 'Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: ASCO Endorsement of CAP Guideline'. Thank you for being here, Dr. Vikas, Dr. Johnson, and Dr. Broaddus. Dr. Praveen Vikas: Sure. Dr. Tyler Johnson: Thanks for having us. Dr. Russell Broaddus: Thank you. Brittany Harvey: First, I'd like to note that ASCO takes great care in the development of its guidelines, and ensuring that the ASCO Conflict of Interest policy is followed for each guideline product. The full conflict of interest information for this guideline endorsement panel is available online with the publication of the guideline endorsement in the Journal of Clinical Oncology. To start, Dr. Vikas, do you have any relevant disclosures that are directly related to this guideline topic? Dr. Praveen Vikas: I don't. Brittany Harvey: And Dr. Johnson, do you have any relevant disclosures that are directly related to this guideline? Dr. Tyler Johnson: I do not. Brittany Harvey: And finally, Dr. Broaddus, do you have any relevant disclosures that are directly related to this guideline topic? Dr. Russell Broaddus: I do not. Brittany Harvey: Great. Thank you all for providing that information. So, starting us off on the content of this endorsement, Dr. Vikas, what is the scope of this guideline endorsement? Dr. Praveen Vikas: So, as you can see from the topic and headline, the guideline endorsement was focused on mismatch repair and microsatellite instability testing for immune checkpoint inhibitor therapy, and this is basically an endorsement by ASCO, of a guideline that was developed jointly by CAP, and others. Brittany Harvey: Great. And then you just mentioned that this is an endorsement of the guideline developed by CAP and other organizations. Can you provide us an overview of how this guideline endorsement process works? Dr. Praveen Vikas: ASCO definitely takes great pride in endorsing some of the guidelines that are relevant to our cancer community, and of course, mismatch repair and microsatellite instability testing has been one of those areas where there is a lack of clear guidance. So, when we were approached from CAP about endorsing this guideline, we definitely realized that there's not much published from most of our oncology community, so we were very excited about looking into this guideline and endorsing it. So, this was very much for a topic that we thought is very useful and very timely. Brittany Harvey: And that's great to hear. So then, Dr. Broaddus, as an author both on the guideline endorsement and a