{"title":"CDK4/6 inhibition to resensitize BRAF/EGFR inhibitor in patient-derived BRAF/PTEN-mutant colon cancer cells.","authors":"Sung Hee Lim, Song-Yi Lee, Jung Yong Hong, Jeeyun Lee, Seung Tae Kim","doi":"10.21037/tcr-24-20","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>In v-raf murine sarcoma viral oncogene homolog B1 (BRAF)-mutant colorectal cancer (CRC), encorafenib-cetuximab has been established as standard second-line therapy, but not all patients respond and the duration of response is relatively short. Overcoming intrinsic or acquired resistance to BRAF/EGFR inhibitors is crucial for enhancing treatment outcomes in metastatic BRAF-mutated CRC. The aim of the study is to investigate the resistance mechanisms in BRAF-mutant CRC patient refractory to BRAF/EGFR targeted therapy.</p><p><strong>Methods: </strong>We established patient-derived cells (PDCs) from a patient with BRAF/PTEN-mutant metastatic colon cancer who progressed rapidly on encorafenib plus cetuximab. To explore potential treatment options for inherent resistance caused by simultaneous PTEN mutation in BRAF-mutated CRC, we conducted cell viability assays using PDCs treated with encorafenib-cetuximab in combination with a cyclin-dependent kinase-4 and 6 (CDK4/6) inhibitor.</p><p><strong>Results: </strong>The patient's tumor had concurrent PTEN loss-of-function alteration at diagnosis and PDCs were generated from ascites after resistance to the BRAF/EGFR inhibitor. The PDCs were resistant to the encorafenib-cetuximab combination even at a high concentration of cetuximab (up to 500 µg/mL). Adding the CDK4/6 inhibitor, ribociclib, to encorafenib-cetuximab showed a synergistic effect in a proliferation assay. Ribociclib plus encorafenib-cetuximab represented a significantly lower expression of Ki-67 compared to the dual combination alone. An MTS assay showed that triplet therapy with ribociclib, encorafenib, and cetuximab suppressed cell viability more efficiently than the two-drug combinations. Investigating the combined effect of triplet therapy using the calculated combination index (CI) showed that ribociclib had a synergistic effect with encorafenib-cetuximab when applied to PDCs with a concurrent BRAF/PTEN mutation.</p><p><strong>Conclusions: </strong>Our results suggest that combining the CDK4/6 inhibitor with the BRAF/EGFR inhibitor might be a novel treatment strategy for concomitant BRAF and PTEN-mutant CRC.</p>","PeriodicalId":23216,"journal":{"name":"Translational cancer research","volume":null,"pages":null},"PeriodicalIF":1.5000,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11319972/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Translational cancer research","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.21037/tcr-24-20","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/7/12 0:00:00","PubModel":"Epub","JCR":"Q4","JCRName":"ONCOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background: In v-raf murine sarcoma viral oncogene homolog B1 (BRAF)-mutant colorectal cancer (CRC), encorafenib-cetuximab has been established as standard second-line therapy, but not all patients respond and the duration of response is relatively short. Overcoming intrinsic or acquired resistance to BRAF/EGFR inhibitors is crucial for enhancing treatment outcomes in metastatic BRAF-mutated CRC. The aim of the study is to investigate the resistance mechanisms in BRAF-mutant CRC patient refractory to BRAF/EGFR targeted therapy.
Methods: We established patient-derived cells (PDCs) from a patient with BRAF/PTEN-mutant metastatic colon cancer who progressed rapidly on encorafenib plus cetuximab. To explore potential treatment options for inherent resistance caused by simultaneous PTEN mutation in BRAF-mutated CRC, we conducted cell viability assays using PDCs treated with encorafenib-cetuximab in combination with a cyclin-dependent kinase-4 and 6 (CDK4/6) inhibitor.
Results: The patient's tumor had concurrent PTEN loss-of-function alteration at diagnosis and PDCs were generated from ascites after resistance to the BRAF/EGFR inhibitor. The PDCs were resistant to the encorafenib-cetuximab combination even at a high concentration of cetuximab (up to 500 µg/mL). Adding the CDK4/6 inhibitor, ribociclib, to encorafenib-cetuximab showed a synergistic effect in a proliferation assay. Ribociclib plus encorafenib-cetuximab represented a significantly lower expression of Ki-67 compared to the dual combination alone. An MTS assay showed that triplet therapy with ribociclib, encorafenib, and cetuximab suppressed cell viability more efficiently than the two-drug combinations. Investigating the combined effect of triplet therapy using the calculated combination index (CI) showed that ribociclib had a synergistic effect with encorafenib-cetuximab when applied to PDCs with a concurrent BRAF/PTEN mutation.
Conclusions: Our results suggest that combining the CDK4/6 inhibitor with the BRAF/EGFR inhibitor might be a novel treatment strategy for concomitant BRAF and PTEN-mutant CRC.
期刊介绍:
Translational Cancer Research (Transl Cancer Res TCR; Print ISSN: 2218-676X; Online ISSN 2219-6803; http://tcr.amegroups.com/) is an Open Access, peer-reviewed journal, indexed in Science Citation Index Expanded (SCIE). TCR publishes laboratory studies of novel therapeutic interventions as well as clinical trials which evaluate new treatment paradigms for cancer; results of novel research investigations which bridge the laboratory and clinical settings including risk assessment, cellular and molecular characterization, prevention, detection, diagnosis and treatment of human cancers with the overall goal of improving the clinical care of cancer patients. The focus of TCR is original, peer-reviewed, science-based research that successfully advances clinical medicine toward the goal of improving patients'' quality of life. The editors and an international advisory group of scientists and clinician-scientists as well as other experts will hold TCR articles to the high-quality standards. We accept Original Articles as well as Review Articles, Editorials and Brief Articles.