SENEX-mediated CDK4/6 inhibition promotes senescence and confers apoptosis resistance in B-cell non-Hodgkin lymphoma

Background:The primary cause of treatment failure in patients with refractory or relapsed B-cell non-Hodgkin lymphoma(r/r B-NHL)is resistance to current therapies,and therapy-induced senescence(TIS)stands out as a crucial mechanism contributing to tumor drug resistance.Here,we analyzed SENEX/Rho GTPase Activating Protein 18(ARHGAP18)expression and prognostic significance in doxorubicin-induced B-NHL-TIS model and r/r B-NHL patients,investigating its target in B-NHL cell senescence and the effect of combining specific inhibitors on apoptosis resistance in B-NHL-TIS cells.Methods:Raji cells were transfected with the human SENEX shRNA recombinant lentiviral vector(Sh-SENEX)and the empty vector negative(NC)to construct a stable transfection cell line with knockdown of SENEX.Effect of SENEX-silencing on B-NHL-TIS formation,cell function and cell cycle-related pathways was analyzed.Using doxorubicin(DOX)-inducible senescent B-NHL cells combined with the specific cyclin dependent kinase 4/6(CDK4/6)inhibitor Palbociclib to observe that blocking CDK4/6 effects on TIS formation.SENEX expression of 21 B-NHL patients and 8 healthy controls were analyzed by qRT-PCR,and the correlation between its expression and clinical indicators were evaluated.Results:The downregulation of SENEX expression promotes G1-S phase transition and apoptosis while inhibiting cell proliferation,collectively suppressing the formation of TIS in B-NHL.Blockade of CDK4/6 promotes the DOX-induced G1 phase arrest to enhance TIS formation in B-NHL cells which can reverse the regulatory effect of silencing SENEX on B-NHL cell cycle regulation and senescence.The expression levels of SENEX were notably elevated in B-NHL patients compared to healthy controls,and Elevated expression levels of SENEX were associated with poor prognosis of B-NHL patients.Conclusions:SENEX enhances apoptosis resistance in B-NHL by inhibiting CDK4/6,thereby preventing G1-S phase transition and promoting TIS formation.

Clinical benefit and safety profile of cross-line therapy with CDK4/6 inhibitors:a retrospective study of HR+/HER2–advanced breast cancer

Objective:CDK4/6 inhibitors(CDK4/6is)in combination with endocrine therapy have secured a central role in the treatment of hormone receptor(HR)-positive advanced breast cancer(ABC)and have transformed the therapeutic landscape.Cross-line CDK4/6i therapy in which another CDK4/6i is continued after progression on a prior CDK4/6i may still offer advantageous therapeutic effects.Cross-line CDK4/6i therapy is an area of active investigation in the ongoing pursuit to improve outcomes for patients with HR+/human epidermal growth factor receptor 2(HER2)–ABC.Methods:This retrospective study enrolled 82 patients with HR+/HER2–ABC who were treated with cross-line CDK4/6is(abemaciclib,palbociclib,ribociclib,and dalpiciclib)after progression with another CDK4/6i.The primary endpoint was progression-free survival(PFS)according to version 1.1 of the Response Evaluation Criteria in Solid Tumors.Secondary endpoints included toxicity,objective response rate,disease control rate,and overall survival.Adverse events(AEs)were graded according to version 5.0 of the Common Terminology Criteria for Adverse Events,as promulgated by the U.S.Department of Health and Human Services.Results:Eighty-two HR+/HER2–ABC patients who received cross-line CDK4/6i therapy from January 2022 to February 2024 were enrolled.The median age of the patients was 60 years.The median PFS of all patients was 7.6 months(95%CI,5.9-9.2).Cox regression analysis identified lung metastasis and a switch to endocrine therapy following prior CDK4/6i therapy as independent predictive factors for PFS.Notably,patients who previously received abemaciclib and switched to palbociclib upon disease progression had a median PFS of 10.7 months.The strategy of transitioning to chemotherapy after progression on a prior CDK4/6i,then to a subsequent CDK4/6i merits further investigation.Hematologic toxicity was the most common grade≥3 AEs.No instances of fatal safety events were observed.Conclusions:Cross-line CDK4/6i therapy is associated with significant clinical benefits and manageable safety profiles in patients with HR+/HER2–ABC,which underscores cross-line CDK4/6i therapy potential as an effective treatment strategy.

CDK4/6抑制剂在HR^(+)晚期乳腺癌治疗中的耐药机制及进展后治疗策略

细胞周期蛋白依赖性激酶4/6(CDK4/6)抑制剂联合内分泌治疗已成为激素受体阳性(HR^(+))、人类表皮生长因子受体-2阴性(HER2^(-))乳腺癌患者的晚期一线及二线标准治疗方案。尽管CDK4/6抑制剂可实现有效的疾病控制,但对于晚期乳腺癌患者最终仍会因耐药出现疾病进展。目前CDK4/6抑制剂相关耐药机制尚不完全清楚,同时治疗失败后的最佳治疗策略仍是一个亟待解决的问题。本文就CDK4/6抑制剂的潜在耐药机制和后续治疗策略的最新研究进展做一综述。

LA-D-B1,a novel Abemaciclib derivative,exerts anti-breast cancer effects through CDK4/6

Background:Regulatory proteins involved in human cellular division and proliferation,cyclin-dependent kinases 4 and 6(CDK4/6)are overexpressed in numerous cancers,including triple-negative breast cancer(TNBC).TNBC is a common pathological subtype of breast cancer that is prone to recurrence and metastasis,and has a single treatment method.As one of the CDK4/6 inhibitors,abemaciclib can effectively inhibit the growth of breast tumors.In this study,we synthesized LA-D-B1,a derivative of Abemaciclib,and investigated its anti-tumor effects in breast cancer.Methods:Cellular viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assay.Cell cloning and migration abilities were determined by colony formation assay and wound healing assay.Cell invasion abilities and adhesion were determined by cell invasion assay and cell adhesion assay.The impact of compound LA-D-B1 on cell proliferation and the cell cycle was analyzed through Western blotting,which quantified the levels of proteins associated with the cyclin-dependent kinase(CDK)4/6-cyclin D-Rb-E2F pathway.The in vivo anti-tumor activity of compound LA-D-B1 was investigated using a chick chorioallantoic membrane(CAM)model.Results:The study demonstrated that LA-D-B1 effectively suppressed breast cancer cell proliferation,induced apoptosis,and caused cell cycle arrest.Furthermore,LA-D-B1 reduced the expression of key proteins in the CDK4/6-cyclin D-Rb-E2F pathway,including CDK4,CDK6 and E2F1.The results also indicated significant antitumor activity of LA-D-B1 in a transplanted tumor model.Conclusion:In this study,LA-D-B1 demonstrated a potent anti-tumor effect by effectively suppressing cell proliferation and inhibiting cell cycle progression in breast cancer.These findings highlight the potential of LA-D-B1 as a valuable compound for enhancing therapeutic outcomes and controlling the progression of breast cancer.

CDK4/6 inhibitors in the treatment of hormone receptor-positive, HER2-negative advanced breast cancer

Endocrine therapy(ET)is the therapy backbone of hormone receptor(HR)-positive and human epidermal growth factor receptor 2(HER2)-negati ve advanced breast cancer.However,there are about 20%HR positive patients with no response to ET due to primary or acquired ET resistance.In this background,many agents have been studied to overcome ET resistance and of which the important agents are cyclin-dependent kinase 4/6(CDK4/6)inhibitors.The prognosis of advanced breast cancer has been improved by combing ET with CDK4/6 inhibitors.In this review,we mainly focused on the CDK4/6 inhibitors in the treatment of HR-positive,HER2-negative advanced breast cancer and discussed the action mechanisms of CDK4/6 inhibitors alone or combined with ET.We also summarized several molecular features that would predict response or resistance to CDK4/6 inhibitors.In addition,we put forward possible strategies to overcome CDK4/6 inhibitor resistance according to the latest research.

Insights into the Use of CDK 4/6 Inhibitors in Patients with HR-positive Advanced or Metastatic Breast Cancer

Hormone receptor(HR)-positive breast cancer(BC)is the most common subtype of BC and some patients with such tumors experience recurrences.Endocrine-based therapy(ET)(e.g.,tamoxifen,aromatase inhibitors(AIs),and fulvestrant)that has improved outcomes in such patients represents the initial therapy for women with HR-positive/human epidermal growth factor receptor 2(HER2)-negative BC(considering no evidence of visceral crisis).However,the resistance to ET can occur in almost 50%of HR-positive BCs.In order to improve outcomes of patients with HR-positive metastatic BC,new treatment strategies are required.One such therapy is the new class of medications,cyclin-dependent kinase(CDK)4/6 inhibitors,that have improved the outcomes in such patients(both endocrine-sensitive and endocrine-resistant).This article presents evidence from the main clinical trials,which led to the approval of palbociclib,ribociclib,and abemaciclib.These three CDK 4/6 inhibitors have shown a significant improvement of the progression-free survival(PFS)in patients with HR-positive/HER2-negative metastatic BC when used in combination with selected ETs.In addition,some important patient management considerations,when choosing a particular CDK 4/6 inhibitor for an individual patient are presented.Furthermore,a need to find biomarkers for CDK 4/6 inhibitor sensitivity,efficacy,and resistance,to be able to precisely select the best patientcandidates for this treatment is highlighted.

Progress of CDK4/6 inhibitors in the treatment of malignant tumors

CDK4/6 inhibitor acts on cell cycle.It can be used alone or in combination to treat lung cancer,liver cancer,pancreatic cancer and other cancers by restoring normal cell cycle,triggering anti-tumor immunity and changing the microenvironment of tumors.It has a certain therapeutic effect,and has a certain inhibitory effect on the proliferation and development of malignant tumors.The combination of other antineoplastic drugs can effectively reduce the emergence of drug resistance and synergistically enhance the clinical efficacy.This article reviews the related research results of CDK4/6 inhibitors,as well as the literature,and summarizes the mechanism and clinical application of CDK4/6 inhibitors.Cyclin dependent kinase(CDK)is a group of serine/threonine protein kinases.The chemical action of CDK on serine/threonine protein is the key to driving cell cycle.The typical biological feature of cancer is cell cycle disorder.As the engine of cell cycle,CDK and its regulators play an important role in tumorigenesis and development.In modern times,cancer has gained a deeper understanding at the level of biomolecule.For cell receptors,more and more drugs are used for key genes.The new generation of CDK4/6 inhibitors cut into the cell cycle to treat malignant tumors,prevent cells from G1 phase to S phase.They have good clinical efficacy for ER+breast cancer patients.They are also used in clinical trials of lung cancer,melanoma and other malignant tumors to treat malignant tumors.Therapy provides a new way.

Impact of Drug-Drug Interaction between CDK4/6 Inhibitors and Proton Pump Inhibitors on Survival Outcomes in the Treatment of Metastatic Breast Cancer—Real World Data from a Portuguese Center

Introduction: Proton pump inhibitors (PPi) are widely prescribed, including in patients undergoing treatment for advanced breast cancer (ABC). Due to the pharmacokinetic characteristics of the CDK4/6 inhibitor (Ci) palbociclib a drug interaction with PPi was hypothesized. It was shown in a retrospective study that this association was an independent predictive factor for worse progression-free survival (PFS). Objective: To verify the impact of concomitant administration of PPi with Ci on overall survival (OS) and PFS. Material and Methods: This is a retrospective cohort study of patients treated with Ci for HR+HER2-ABC in the period from Feb/2017 to Aug/2020. SPSS software was used for data processing. Univariate analysis was done by the Kaplan-Meier method and log-rank test, and multivariate analysis by COX regression. P-value < 0.05 was considered significant. Results: 80 patients were included. The median age at diagnosis of ABC was 56 years (25 - 75). Treatment with Ci was 1st line for ABC in 68.8%. Choice of Ci was palbociclib in 73.8% (n = 59) and ribociclib in 26.3% (n = 21). The hormone partner was a nonsteroidal aromatase inhibitor in 45.0%, and fulvestrant in 55.0% of cases. 37.5% of patients were on PPi, and 70.0% of them were during the entire treatment (23.3% omeprazole, 73.4% pantoprazole, 3.3% others). Patients taking concomitant PPi and Ci had lower OS (OS-3 years 42.6% vs. 63.4%, p = 0.254) and PFS (PFS med 15 m. vs. 21 m., p = 0.733), although with no statistically significant difference. Discussion: In the sample, there was a numerical difference, without the statistical significance in the use of PPi in the survival of patients under Ci. This difference could be more evident with a longer follow-up and a larger sample size. This study intends to alert to the growing importance of checking for drug interactions. Polymedication, advanced age and the presence of several comorbidities are real problems in patients with ABC. Conclusion: Real-world data from this center demonstrate a negative, non-statistically significant impact of PPi treatment on survival outcomes, in patients treated with Ci for HR+HER2-ABC.

A Systematic Review of Economic Evaluation of CDK4/6 Inhibitors in HR+/HER2-Advanced Breast Cancer

Objective To review the domestic and foreign economic studies on CDK4/6 inhibitors in first-line or second-line treatment of HR+/HER2-advanced breast cancer,and to analyze the main methodologies and research results.Methods Systematic literature review was used to search PubMed,EMBASE,Cochrane Library,CNKI,CBM,and Wanfang database.The incremental cost-effectiveness ratio was taken as the main outcome index,and all pharmacoeconomic evaluations with CDK4/6 inhibitors as intervention measures were included,such as Palbociclib,Ribociclib,and Abemaciclib.According to the Quality of Health Economic Studies Instrument,the quality of the included articles was evaluated,and then the included literature was analyzed.Results and Conclusion A total of 16 pharmacoeconomic evaluation studies were included,mainly from the perspective of national healthcare systems or third-party payers.Only 2 studies focused on second-line treatment,and the remaining treatment levels were first-line treatment.In terms of model structure,7 studies adopted the Markov model,6 studies adopted the PSM model,and 3 studies adopted the DES model.The basic analysis results showed that CDK4/6 inhibitor combined with endocrine regimen was not economical compared with endocrine alone regimen when the threshold was the conventional willingness to pay(WTP)value of each country.The uncertainty analysis included deterministic sensitivity analysis and probability sensitivity analysis.The included studies are all Cost-Utility Analysis with high-quality evaluation,which can provide evidence support for health-related decision-makers in decision-making.It can also provide methodological reference for the economic evaluation of other targeted drugs.

CDK4/6抑制剂耐药机制的研究进展

细胞周期依赖性激酶4/6(cyclin-dependent kinase 4/6,CDK4/6)抑制剂能作用于过度活化的CDK4/6,恢复正常细胞周期,并通过触发免疫,改变肿瘤微环境等发挥抗肿瘤作用。目前,CDK4/6抑制剂的问世极大地改善了激素受体阳性(hormone receptor-positive,HR^(+))、人表皮生长因子受体2阴性(human epidermal growth factor receptor 2-negative,HER2^(-))晚期乳腺癌患者的预后,使无进展生存期(progression-free-survival,PFS)增加近一倍,且不良反应可控。尽管如此,这类患者最终仍会因CDK4/6抑制剂耐药而出现疾病进展。CDK4/6抑制剂的耐药机制十分复杂,尚未完全明确。预测其早期耐药或治疗敏感的生物标记物也有待确定。本文对CDK4/6抑制剂治疗的作用机制及耐药机制进行梳理和总结,并对疾病进展后的治疗策略作简要讨论。

Inhibition of Eukaryotic Initiating Factor eIF4E Overcomes Abemaciclib Resistance in Gastric Cancer

Objective Aberrant activating mutations in cyclin-dependent kinases 4 and 6(CDK4/6)are common in various cancers,including gastroesophageal malignancies.Although CDK4/6 inhibitors,such as abemaciclib and palbociclib,have been approved for breast cancer treatment,their effectiveness as a monotherapy remains limited for gastroesophageal tumors.The present study explored the underlying mechanism of abemaciclib resistance.Methods Abemaciclib-resistant gastric cancer cell lines were generated,and the phospho-eukaryotic translation initiation factor 4E(p-eIF4E)and eIF4E expression was compared between resistant and parental cell lines.In order to analyze the role of eIF4E in cell resistance,siRNA knockdown was employed.The effectiveness of ribavirin alone and its combination with abemaciclib was evaluated in the gastric cancer xenograft mouse model.Results The upregulation of eIF4E was a common feature in gastric cancer cells exposed to prolonged abemaciclib treatment.Gastric cancer cells with increased eIF4E levels exhibited a better response to eIF4E inhibition,especially those that were resistant to abemaciclib.Ribavirin,which is an approved anti-viral drug,significantly improved the efficacy of abemaciclib,both in vitro and in vivo,by inhibiting eIF4E.Importantly,ribavirin effectively suppressed the abemaciclib-resistant gastric cancer growth in mice without causing toxicity.Conclusion These findings suggest that targeting eIF4E can enhance the abemaciclib treatment for gastric cancer,proposing the potential combination therapy of CDK4/6 inhibitors with ribavirin for advanced gastric cancer.

CDK4/6抑制剂所致药物不良反应文献分析及思考

目的分析CDK4/6抑制剂在临床应用中所致不良反应(ADR)的特点,为临床安全用药提供参考。方法检索维普、中国知网、万方、Web of Science、PubMed等数据库中关于CDK4/6抑制剂致ADRs的文献并进行分析。结果CDK4/6抑制剂致ADRs的个案报道共34例;患者平均年龄约63.5岁,ADRs多发生在用药4个月内(29例,85.29%);CDK4/6抑制剂致ADRs主要以皮肤及其附件损害(14例,41.18%)、呼吸系统损害(6例,17.65%)、肝胆系统损害(4例,11.76%)为主;经停药和/或对症治疗后达到症状好转或治愈的有31例;3例最终死亡。结论临床使用CDK4/6抑制剂时应加强用药监测,开展多学科患者管理,而CDK4/6抑制剂的ADR发生机制尚需进一步研究。

细胞周期依赖性激酶4/6抑制剂在恶性肿瘤治疗中的应用及耐药机制

增殖失控是恶性肿瘤的重要特征之一。细胞周期依赖性激酶4/6(cyclin-dependentkinase 4/6,CDK4/6)抑制剂能作用于各种原因导致的过度活化的CDK4/6,恢复正常细胞周期,并可通过增强免疫、改变肿瘤微环境等发挥抗肿瘤作用。目前,CDK4/6抑制剂在激素受体阳性乳腺癌治疗中取得了良好疗效,已被批准联合内分泌治疗作为此类肿瘤的一线治疗方案,在其他肿瘤中的应用亦逐渐开展,疗效有待验证。对CDK4/6抑制剂天然或获得性耐药是影响其疗效的重要因素,目前激素受体阳性(主要为雌激素受体阳性)能较为准确预测内分泌联合CDK4/6抑制剂治疗的反应性,其他标志物需进一步探索和验证。本文对CDK4/6抑制剂治疗恶性肿瘤的作用机制、应用现状及耐药机制进行梳理和总结,并对当前CDK4/6抑制剂治疗乳腺癌尚存争议的临床决策问题作简要讨论。

Overexpressed Cyclin D1 and CDK4 proteins are responsible for the resistance to CDK4/6 inhibitor in breast cancer that can be reversed by PI3K/mTOR inhibitors

CDK4/6 inhibitors are the standard treatment in advanced HR+/HER2-breast cancer patients.Nevertheless,the resistance to CDK4/6 inhibitors is inevitable and the strategies to overcome resistance are of great interest.Here,we show that the palbociclibresistant breast cancer cells expressed significantly higher levels of Cyclin D1 and CDK4 proteins because of upregulated protein synthesis.Silencing Cyclin D1 or CDK4 led to cell cycle arrest while silencing Cyclin E1 or CDK2 restored the sensitivity to palbociclib.Furthermore,PI3K/mTOR pathway was hyper-activated in palbociclib-resistant cells,leading to more phosphorylated 4E-BP1 and higher levels of Cyclin D1 and CDK4 translation.Targeting PI3K/mTOR pathway with a specific PI3Kαinhibitor(BYL719)or an mTOR inhibitor(everolimus)reduced the protein levels of Cyclin D1 and CDK4,and restored the sensitivity to palbociclib.The tumor samples expressed significantly higher levels of Cyclin D1,CDK4,p-AKT and p-4E-BP1 after progression on palbociclib treatment.In conclusion,our findings suggest that overexpressed Cyclin D1 and CDK4 proteins lead to the resistance to CDK4/6 inhibitor and PI3K/mTOR inhibitors are able to restore the sensitivity to CDK4/6 inhibitors,which provides the biomarker and rationale for the combinational use of CDK4/6 inhibitors and PI3K/mTOR inhibitors after CDK4/6 inhibitor resistance in breast cancer.

Effects of palbociclib on oral squamous cell carcinoma and the role of PIK3CA in conferring resistance

Objective: Lack of effective therapies remains a problem in the treatment of oral squamous cell carcinoma(OSCC), especially in patients with advanced tumors. OSCC development is driven by multiple aberrancies within the cell cycle pathway, including amplification of cyclin D1 and loss of p16. Hence, cell cycle inhibitors of the CDK4/6-cyclin D axis are appealing targets for OSCC treatment. Here, we determined the potency of palbociclib and identified genetic features that are associated with the response of palbociclib in OSCC.Methods: The effect of palbociclib was evaluated in a panel of well-characterized OSCC cell lines by cell proliferation assays and further confirmed by in vivo evaluation in xenograft models. PIK3CA-mutant isogenic cell lines were used to investigate the effect of PIK3CA mutation towards palbociclib response.Results: We demonstrated that 80% of OSCC cell lines are sensitive to palbociclib at sub-micromolar concentrations.Consistently, palbociclib was effective in controlling tumor growth in mice. We identified that palbociclib-resistant cells harbored mutations in PIK3CA. Using isogenic cell lines, we showed that PIK3CA mutant cells are less responsive to palbociclib as compared to wild-type cells with concurrent upregulation of CDK2 and cyclin E1 protein levels. We further demonstrated that the combination of a PI3 K/mTOR inhibitor(PF-04691502) and palbociclib completely controlled tumor growth in mice.Conclusions: This study demonstrated the potency of palbociclib in OSCC models and provides a rationale for the inclusion of PIK3CA testing in the clinical evaluation of CDK4/6 inhibitors and suggests combination approaches for further clinical studies.

Palbociclib:周期蛋白依赖性激酶4/6抑制剂治疗乳腺癌

乳腺癌在我国发病率位居女性恶性肿瘤的第1位。针对雌激素受体(Estrogen receptor,ER)、孕激素受体(Progesterone receptor,PR)的内分泌治疗可延长激素受体(Hormone receptor,HR)阳性乳腺癌患者的生存,是乳腺癌治疗方案的重要组成部分。研究发现HR阳性的乳腺癌生长依赖细胞周期蛋白依赖性激酶(cyclin-dependent kinase,CDK),尤其是CDK4和CDK6,它们可以加快细胞从细胞周期的G1期进入S期的进程,导致细胞的增殖失控。Palbociclib(PD-0332991,lbrance)是一种口服CDK4/6小分子抑制剂。在体外实验和临床试验中,都显示出对于HR阳性乳腺癌生长的抑制,并且与内分泌治疗有协同作用。2015年2月美国FDA批准其联合来曲唑(Letrozole)用于HR阳性和HER2阴性的绝经后晚期(转移性)乳腺癌患者的一线治疗。也有临床试验支持其联合氟维司群应用。本文综述了Palboeiclib的作用机制,体外实验及临床试验。

Liquid biopsies to predict CDK4/6 inhibitor efficacy and resistance in breast cancer

Cyclin-dependent kinase 4 and 6(CDK4/6)inhibitors combined with endocrine therapy have transformed the treatment of estrogen receptor-positive(ER+)and human epidermal growth factor receptor 2 negative(HER2-)metastatic breast cancer.However,some patients do not respond to this treatment,and patients inevitably develop resistance,such that novel biomarkers are needed to predict primary resistance,monitor treatment response for acquired resistance,and personalize treatment strategies.Circumventing the spatial and temporal limitations of tissue biopsy,newly developed liquid biopsy approaches have the potential to uncover biomarkers that can predict CDK4/6 inhibitor efficacy and resistance in breast cancer patients through a simple blood test.Studies on circulating tumor DNA(ctDNA)-based liquid biopsy biomarkers of CDK4/6 inhibitor resistance have focused primarily on genomic alterations and have failed thus far to identify clear and clinically validated predictive biomarkers,but emerging epigenetic ctDNA methodologies hold promise for further discovery.The present review outlines recent advances and future directions in ctDNA-based biomarkers of CDK4/6 inhibitor treatment response.

Abemaciclib, a Recent Novel FDA-Approved Small Molecule Inhibiting Cyclin-Dependant Kinase 4/6 for the Treatment of Metastatic Breast Cancer: A Mini-Review

Abemaciclib (Verzerio®) is a cell cycle inhibitor of both CDK4 and CDK6. In 2017, abemaciclib was approved by the Food and Drug Administration (FDA) and, in 2018 by the European Medicines Agency (EMA) for the treatment of postmenopausal women with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2−) advanced breast cancer. In this mini-review, we provide a series of information for respectively their targets and its selectivity, results on preclinical trial, clinical phase I, II and III trials, and some perspectives. We also describe the batch and flow steps used for the synthesis of this cancer drug.

Beyond clinical trials:CDK4/6 inhibitor efficacy predictors and nomogram model from real‐world evidence in metastatic breast cancer

Background:CDK4/6 inhibitors(CDK4/6i)have shown promising results in the treatment of hormone receptor‐positive(HR+)metastatic breast cancer(MBC)when combined with endocrine therapy(ET).It is crucial to evaluate the actual effectiveness and safety of CDK4/6i in clinical practice,as well as to analyze the factors that can predict their outcomes.Methods:Patients with HR+MBC who received CDK4/6i‐based therapy between May 2016 and May 2023 at Hunan Cancer Hospital were evaluated for progression‐free survival(PFS).Adverse reactions were assessed based on the National Cancer Institute Common Toxicity Criteria(version 5.0).Results:This study included 344 patients,with a median PFS(mPFS)of 12.8 months(range:10.4–15.2 months).After adjustment,Cox multivariate regression analysis revealed that visceral metastasis(specifically liver and brain metastases),Eastern Cooperative Oncology Group Performance Status(ECOG PS)≥1,estrogen receptor≤80%,progesterone receptor≤10%,Ki‐67>30%,and treatment in later stages were significant factors associated with reduced PFS.Based on this,we created a prognostic nomogram and validated its performance,obtaining a C‐index of 0.714(95%confidence interval:0.640–0.787)as well as reliable calibration and clinical impact.The mPFS of CDK4/6i rechallenge was 7.7 months;for patients who initially discontinued CDK4/6i for reasons other than disease progression,CDK4/6i rechallenge still provided a mPFS of 11.4 months.The tolerability and safety of combining CDK4/6is with ET were manageable.Adverse events led to treatment discontinuation in 3.8%of patients.Neutropenia(29.1%),leukopenia(13.7%),and anemia(4.1%)were the primary grade 3/4 adverse reactions.Conclusions:This real‐world study highlights the ample efficacy and reasonable safety of combined CDK4/6i and ET in patients with HR+MBC.Individualized treatment decisions and ongoing safety monitoring are important to optimize the therapeutic benefit of CDK4/6i treatment.

FSIP1 enhances the therapeutic sensitivity to CDK4/6 inhibitors in triple-negative breast cancer patients by activating the Nanog pathway

CDK4/6 inhibitors are routinely recommended agents for the treatment of advanced HR+HER2-breast cancer.However,their therapeutic effectiveness in triple-negative breast cancer(TNBC)remains controversial.Here,we observed that the expression level of fibrous sheath interacting protein 1(FSIP1)could predict the treatment response of TNBC to CDK4/6 inhibitors.High FSIP1 expression level was related to a poor prognosis in TNBC,which was associated with the ability of FSIP1 to promote tumor cell proliferation.FSIP1 downregulation led to slowed tumor growth and reduced lung metastasis in TNBC.FSIP1knockout caused cell cycle arrest at the G0/G1 phase and reduced treatment sensitivity to CDK4/6 inhibitors by inactivating the Nanog/CCND1/CDK4/6 pathway.FSIP1 could form a complex with Nanog,protecting it from ubiquitination and degradation,which may facilitate the rapid cell cycle transition from G0/G1 to S phase and exhibit enhanced sensitivity to CDK4/6 inhibitors.Our findings suggest that TNBC patients with high FSIP1 expression levels may be suitable candidates for CDK4/6 inhibitor treatment.