Dr. Rachel Freedman and Dr. Sharon Giordano share the latest rapid guideline update from ASCO on the adjuvant use of the CDK4/6 inhibitors abemaciclib and ribociclib in patients with stage II and III breast cancer. They share details on the impetus for the update, supporting evidence, and considerations of benefits and harms for individuals. Additionally, Drs. Freedman and Giordano discuss what these options mean for clinicians and patients, and outstanding questions regarding optimal adjuvant chemotherapy and targeted therapy for patients with early breast cancer. Read the full rapid update, “Optimal Adjuvant Chemotherapy and Targeted Therapy for Early Breast Cancer – CDK4/6 Inhibitors: ASCO Rapid Guideline Update” at www.asco.org/breast-cancer-guidelines." TRANSCRIPT This guideline, clinical tools, and resources are available at www.asco.org/breast-cancer-guidelines. Read the full text of the guideline and review authors’ disclosures of potential conflicts of interest in the Journal of Clinical Oncology, https://ascopubs.org/doi/10.1200/JCO.24.00886  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. Rachel Freedman from Dana Farber Cancer Institute and Dr. Sharon Giordano from MD Anderson Cancer Center, co-chairs on “Optimal Adjuvant Chemotherapy and Targeted Therapy for Early Breast Cancer – CDK 4/6 Inhibitors: ASCO Rapid Guideline Update.” Thank you for being here, Dr. Freedman and Dr. Giordano. Dr. Rachel Freedman: Hi. It's great to be here, thank you. Dr. Sharon Giordano: Yeah, thank you for having us. Brittany Harvey: Great. Then, before we discuss this guideline, 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. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Freedman and Dr. Giordano, who have joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes. So then, to dive into the content here. First, Dr. Freedman, what prompted this update to the “Optimal Adjuvant Chemotherapy and Targeted Therapy for Early Breast Cancer Guideline”, which was previously updated in 2021? Dr. Rachel Freedman: Yeah, at that time, we published guidelines which were part of an amendment to the previously published 2020 early breast cancer guidelines to include consideration of adjuvant CDK4/6 inhibitor use, because the first data for adjuvant abemaciclib became available from the monarchE trial, and because the FDA had acted to grant approval for the use of abemaciclib in those with node positive disease and a Ki-67 score of at least 20%. Our recommendation at that time was to apply abemaciclib in the greater context of the intention-to-treat population included on the monarchE study. But since that time, the FDA in 2023 expanded its approval for adjuvant abemaciclib for a broader population, removing that Ki-67 requirement that was a part of their initial approval. With this change, the recently published longer term data from the monarchE study and the recently published data from the NATALEE trial and adjuvant ribociclib study, we felt that it was time to update our guidelines to be more relevant to the most current data available. Brittany Harvey: I appreciate you providing that background information on the impetus for this latest update. So then, Dr. Giordano, based on this new data, what are the updated recommendations in the latest version of this guideline? Dr. Sharon Giordano: So we really have two updated recommendations and then two qualifying statements that go with the new recommendations. S