{"entity":{"id":"abemaciclib","kind":"drug","name":"Abemaciclib","aka":[],"tldr":"Abemaciclib was the first CDK4/6 inhibitor approved after surgery for high-risk hormone-positive breast cancer.","summary":"Abemaciclib is a CDK4-biased CDK4/6 inhibitor potent enough for continuous dosing, at 150 mg twice daily with endocrine therapy or 200 mg twice daily alone. MONARCH 2 and 3 established it in HR-positive, HER2-negative advanced breast cancer (overall survival benefit in MONARCH 2), and monarchE made it the first CDK4/6 inhibitor approved after surgery for high-risk node-positive disease (2021, label broadened 2023): 2 years of treatment gave an invasive disease-free survival HR of 0.68 at 5 years (83.6% versus 76.0%), with a favourable but not yet significant overall survival trend. Eli Lilly markets it. Diarrhoea is the defining toxicity (85%, 8% grade 3 or higher). Whether the recurrence benefit becomes a survival benefit is open. For a newcomer: the CDK4/6 pill that first proved it could stop early breast cancer coming back.","status":"approved","asOf":"2026-09-04","wikipedia":"https://en.wikipedia.org/wiki/Abemaciclib","links":[{"label":"FDA label (DailyMed)","url":"https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=Abemaciclib"}],"tags":[],"related":[],"cancers":["breast-hr-positive","hr-positive-early-high-risk","hr-positive-metastatic-post-cdk46"],"sections":[],"technologies":["cdk46-inhibitor"],"targets":["cdk4-6"],"drugs":[],"companies":["eli-lilly"],"institutions":[],"pathways":[],"terms":[],"trials":["monarche","nct02152631","nct03706365","nct05735080","nct06810544","nct05867251","nct05768139","nct07100106","nct06413706","nct06065748","nct05440786","nct02763566","nct05999994","nct05696626","nct07002177","nct02107703","nct05548127","nct02747004","nct05288166","nct04862663","nct06380751","nct06760637","nct05386108","nct05573126","nct07605728"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"brand":"Verzenio","modality":"Small-molecule CDK4/6 inhibitor","mechanism":"CDK4-biased inhibitor with continuous dosing.","approvals":[{"region":"US","year":2017,"indication":"HR+/HER2- advanced breast cancer"},{"region":"US","year":2021,"indication":"Adjuvant high-risk node-positive HR+/HER2- early breast cancer"}],"mechanismSteps":["Oral drug is absorbed and reaches the tumour","Binds the ATP pocket (or allosteric site) of CDK4 (and CDK6)","Phosphorylation of downstream substrates stops","Continuous dosing keeps RB unphosphorylated; less neutropenia, more diarrhoea than the 3-weeks-on drugs","Oncogene-addicted cells arrest and undergo apoptosis"],"dosing":{"route":"Oral, continuous","schedule":"150 mg twice daily with endocrine therapy (2 years adjuvant); 200 mg twice daily as monotherapy","modifications":"Reduce to 100 then 50 mg BID for grade 3 diarrhoea, neutropenia, hepatotoxicity; loperamide at first loose stool","monitoring":"Blood counts and LFTs every 2 weeks for 2 months then monthly; VTE and ILD symptoms","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06"},"toxicity":[{"event":"Diarrhoea","anyGradePct":85,"grade3PlusPct":8,"source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"81-90% any grade; 8-20% grade 3 across trials"},{"event":"Neutropenia","anyGradePct":42,"grade3PlusPct":19,"source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"37-46% any grade; 19-32% grade 3-4"},{"event":"Infections","grade3PlusPct":3,"source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"monarchE / MONARCH 2"},{"event":"Venous thromboembolism","grade3PlusPct":2,"source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"2-5% across trials"},{"event":"Interstitial lung disease","grade3PlusPct":0.5,"source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"monarchE / MONARCH 2"},{"event":"Fatigue","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"monarchE / MONARCH 2"},{"event":"Nausea","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"monarchE / MONARCH 2"},{"event":"Anaemia","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"monarchE / MONARCH 2"},{"event":"ALT increased","source":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=be4bc0de-0fdc-4d46-8d25-be43c79e6a06","note":"monarchE / MONARCH 2"}],"access":[{"country":"US","reimbursement":"Medicare Part D (oral); commercial plans per formulary, often with prior authorisation","assistance":"https://www.lillycares.com","source":"https://www.cms.gov/medicare/payment/part-b-drugs/asp-pricing-files","asOf":"2026-09-06"},{"country":"UK","reimbursement":"NICE: recommended with fulvestrant (TA579), aromatase inhibitor (TA563), and adjuvant (TA810)","source":"https://www.nice.org.uk/guidance/published?ngt=Technology%20appraisal%20guidance","asOf":"2026-09-06"}],"regulatoryEvents":[{"date":"2017-09-28","type":"approval","region":"US","note":"With fulvestrant after endocrine therapy, and as monotherapy after chemotherapy (MONARCH 2/1)","source":"https://www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications"},{"date":"2026-09-18","type":"approval","region":"US","note":"With imlunestrant, for ER-positive, HER2-negative, ESR1-mutated advanced or metastatic breast cancer","source":"https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-imlunestrant-combination-abemaciclib-er-positive-her2-negative-esr1-mutated-advanced-or"},{"date":"2018-02-26","type":"approval","region":"US","note":"With aromatase inhibitor first line (MONARCH 3)","source":"https://www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications"},{"date":"2021-10-12","type":"approval","region":"US","note":"Adjuvant high-risk node-positive HR+/HER2- early breast cancer, Ki-67 ≥20% (monarchE)","source":"https://www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications"},{"date":"2023-03-03","type":"label-change","region":"US","note":"Adjuvant indication broadened to remove Ki-67 requirement","source":"https://www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications"}]},"route":"/drugs/abemaciclib/","neighbours":{"cancer":[{"id":"advanced-recurrent-endometrial-cancer","kind":"cancer","name":"Advanced or recurrent endometrial cancer","route":"/cancers/advanced-recurrent-endometrial-cancer/"},{"id":"endometrial","kind":"cancer","name":"Endometrial cancer","route":"/cancers/endometrial/"},{"id":"endometrial-nsmp","kind":"cancer","name":"Endometrial cancer with no specific molecular profile","route":"/cancers/endometrial-nsmp/"},{"id":"hr-positive-early-high-risk","kind":"cancer","name":"High-risk early HR-positive breast cancer","route":"/cancers/hr-positive-early-high-risk/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"},{"id":"hr-positive-metastatic-post-cdk46","kind":"cancer","name":"HR-positive metastatic breast cancer after CDK4/6 inhibitors","route":"/cancers/hr-positive-metastatic-post-cdk46/"},{"id":"invasive-lobular-carcinoma","kind":"cancer","name":"Invasive lobular carcinoma of the breast","route":"/cancers/invasive-lobular-carcinoma/"},{"id":"male-breast-cancer","kind":"cancer","name":"Male breast cancer","route":"/cancers/male-breast-cancer/"}],"technology":[{"id":"cdk46-inhibitor","kind":"technology","name":"CDK4/6 inhibitors","route":"/technologies/cdk46-inhibitor/"}],"target":[{"id":"cdk4-6","kind":"target","name":"CDK4/6","route":"/targets/cdk4-6/"}],"company":[{"id":"eli-lilly","kind":"company","name":"Eli Lilly (incl. 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