Dr. Vamsi Velcheti and Dr. Benjamin Neel, of the NYU Langone Perlmutter Cancer Center, and Dr. John Heymach, of MD Anderson Cancer Center, discuss new therapeutic approaches for KRAS-mutant lung cancers and therapy options for RAS-altered tumors.   TRANSCRIPT Dr. Vamsidhar Velcheti: Hello, I'm Dr. Vamsidhar Velcheti, your guest host for the ASCO Daily News podcast today. I'm the medical director of the Thoracic Oncology Program at Perlmutter Cancer Center at NYU Langone Health. I'm delighted to welcome two internationally renowned physician-scientists, Dr. John Heymach, the chair of Thoracic-Head & Neck Medical Oncology at the MD Anderson Cancer Center, and my colleague, Dr. Benjamin Neel, the director of the Perlmutter Cancer Center at NYU Langone Health, and professor of Medicine at NYU Grossman School of Medicine. So, we'll be discussing new therapeutic approaches today for KRAS-mutant lung cancers, and we will talk about emerging new targeted therapy options for RAS-altered tumors. Our full disclosures are available in the show notes, and the disclosures of all the guests of the podcast can be found on our transcript at: asco.org/podcast. Dr. Heymach and Dr. Neel, it's such a great pleasure to have you here for the podcast today. Dr. John Heymach: My pleasure to be here. Dr. Benjamin Neel: Same here. Dr. Vamsidhar Velcheti: Dr. Neel, let's start off with you. As you know, RAS oncogenes were first discovered nearly four decades ago. Why is RAS such a challenging therapeutic target? Why has it taken so long to develop therapeutic options for these patients? Dr. Benjamin Neel: Well, I think a good analogy is the difference between kinase inhibitors and RAS inhibitors. So, kinase inhibitors basically took advantage of an ATP-binding pocket that's present in all kinases, but is different from kinase to kinase, and can be accessed by small molecule inhibitors. So, the standard approach that one would've thought of taking, would be to go after the GTP-binding pocket. The only problem is that the affinity for binding GTP by KRAS is three to four orders of magnitude higher. So, actually getting inhibitors that are GTP-binding inhibitors is pretty much very difficult. And then, until recently, it was felt that RAS was a very flat molecule and there weren't any surfaces that you could stick a small molecule inhibitor in. So, from a variety of biochemical and medicinal-pharmacological reasons, RAS was thought to be impervious to small molecule development. But as is often the case, a singular and seminal insight from a scientist, Kevan Shokat, really broke the field open, and now there's a whole host of new approaches to trying to drug RAS. Dr. Vamsidhar Velcheti: So, Dr. Neel, can you describe those recent advances in drug design that have enabled these novel new treatments for KRAS-targeted therapies? Dr. Benjamin Neel: So, it starts actually with the recognition that for many years, people were going after the wrong RAS. And by the wrong RAS, the overwhelming majority of the earlier studies on the structure, and for that matter, the function of RAS centered on HRAS or Harvey RAS. We just mutated in some cancers, most prominently, bladder cancer, and head & neck cancer, but not on KRAS, which is the really major player in terms of oncogenes in human cancer. So, first of all, we were studying the wrong RAS. The second thing is that we were sort of thinking that all RAS mutants were the same. And even from the earliest days, back in the late eighties, it was pretty clear that there were different biochemical properties in all different RAS mutants. But this sort of got lost in the cause and in the intervening time, and as a result, people thought all RASes were the same and they were just studying mainly G12V and G12D, which are more difficult to drug. And then, the third and most fundamental insight was the idea of trying to take advantage of a particular mutation in KRAS, which is present in a large fraction of lung cancer patients,