bims-cyhorp Biomed News
on Cyclin-dependent kinases in hormone receptor positive breast cancer
Issue of 2023‒04‒02
eight papers selected by
Piotr Okupski,



  1. Cancers (Basel). 2023 Mar 14. pii: 1763. [Epub ahead of print]15(6):
      PURPOSE OF REVIEW: Tamoxifen and aromatase inhibitors can be considered as some of the first targeted therapies. For the past 30 years, they were the endocrine treatment standard in the advanced and early breast cancer setting. CDK4/6 inhibitors, however, are the first substances in almost two decades to broadly improve the therapeutic landscape of hormone receptor-positive breast cancer patients for the upcoming years. This review is designed to discuss the recent history, current role, future directions and opportunities of this substance class.RECENT FINDINGS: The CDK4/6 inhibitors abemaciclib, dalpiciclib, palbociclib and ribociclib have all demonstrated a statistically significant improvement in progression-free survival in advanced disease. However, to date, abemaciclib and ribociclib are the only CDK4/6 inhibitors to have shown an improvement in overall survival in patients with metastatic breast cancer. Moreover, abemaciclib is the first CDK4/6 inhibitor to also reduce the risk of recurrence in those with early-stage disease. Further CDK inhibitors, treatment combinations with other drugs and different therapy sequences are in development.
    SUMMARY: Achieving significant improvements in survival rates in the advanced and early breast cancer treatment setting, CDK4/6 inhibitors have set a new standard of care for patients with advanced breast cancer. It remains important to better understand resistance mechanisms to be able to develop novel substances and treatment sequences.
    Keywords:  CDK4/6 inhibitor; abemaciclib; breast cancer; dalpiciclib; endocrine treatment; palbociclib; ribociclib
    DOI:  https://doi.org/10.3390/cancers15061763
  2. Front Oncol. 2023 ;13 1067264
      Cancer treatment-related adverse events (AEs) are sometimes associated with outcomes for cancer patients, especially with the newest therapies such as target therapy and immunotherapy. A few years ago, the first-line therapy for hormone-receptor-positive metastatic breast cancer (mBC) patients has been deeply changed by the introduction of cyclin-dependent kinase (CDK) 4/6 inhibitors, and now, we are improving our knowledge about their AEs and significance in clinical practice. Here, we report our experience with two cases of vitiligo-like lesions that occur early during treatment with ribociclib. We tried to change the CDK4/6 inhibitor for one patient, but the skin reaction persisted. Both patients retained only the endocrine therapy alone and had an unexpected durable progression-free survival (PFS). Some data on skin toxicities, including vitiligo-like lesions by CDK4/6 inhibitors, have recently been reported in the literature, but for the first time, we highlight a possible correlation with improved survival outcomes of patients. Uncovering the etiology of this toxicity, verifying the involvement of the immune system, and demonstrating a possible positive impact in survival represent an intriguing research objective for the near future.
    Keywords:  CDK4/6 inhibitor; breast cancer; lymphocytic infiltration; skin adverse event; vitiligo
    DOI:  https://doi.org/10.3389/fonc.2023.1067264
  3. Adv Ther. 2023 Mar 30.
      INTRODUCTION: Breast cancer in males constitutes approximately 1% of all breast cancer cases globally. Despite extensive treatment experience with abemaciclib in women with metastatic breast cancer (MBC), real-world evidence in male MBC is lacking.METHODS: This analysis was a part of a broader, retrospective study that analyzed electronic medical records and charts of 448 men and women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) MBC who initiated an abemaciclib-containing regimen from January 2017 through September 2019. Data were collected from the Florida Cancer Specialists & Research Institute and the Electronic Medical Office Logistics Health Oncology Warehouse Language™ databases and summarized descriptively. Real-world best response was described: complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD).
    RESULTS: Data for six male patients with MBC who were treated with abemaciclib in combination with an aromatase inhibitor (AI) or fulvestrant are presented. Four patients were aged ≥ 75 years, and four patients had ≥ 3 metastatic sites, including visceral involvement. Abemaciclib was initiated in/after third-line (≥ 3L) in four patients, and patients had history of treatment with AI (n = 4), chemotherapy (n = 3), and/or prior cyclin-dependent kinase 4 and 6 inhibitors (n = 2) in the metastatic setting. Abemaciclib + fulvestrant was the most common abemaciclib-containing regimen (n = 4). Best response was documented in four patients: 1 each with CR, PR, SD, and PD.
    CONCLUSION: Prevalence of male MBC in this dataset was consistent with expected prevalence in the broader population. Most male patients received an abemaciclib-containing regimen in ≥ 3L, with anti-cancer activity observed despite heavy metastatic burden and prior treatments in a metastatic setting.
    Keywords:  Abemaciclib; Male patients; Metastatic breast cancer; Outcome; Treatment pattern
    DOI:  https://doi.org/10.1007/s12325-023-02471-8
  4. Breast Cancer Res Treat. 2023 Mar 31.
      PURPOSE: The combination of cyclin-dependent kinase 4/6 inhibitors and endocrine therapy is a standard treatment for hormone receptor (HR)-positive/human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC); however, their toxicities and financial burden are major issues, especially for prolonged treatment. We investigated fulvestrant plus palbociclib in patients with HR-positive MBC resistant to fulvestrant monotherapy.METHODS: Patients who initially received fulvestrant as their first- or second-line endocrine therapy were assigned to group A. Patients with disease progression during fulvestrant monotherapy who subsequently received fulvestrant plus palbociclib were assigned to group B. The primary endpoint was progression-free survival (PFS1) in group B. We set the threshold median PFS of 5 months (null hypothesis).
    RESULTS: Between January 2018 and February 2020 we enrolled 167 patients in group A (January 2018-February 2020) from 55 institutions, of whom 72 subsequently received fulvestrant plus palbociclib and were enrolled in group B. The median follow-up was 23.8 and 8.9 months in groups A and B, respectively. The median PFS in group B (combination therapy) was 9.4 (90% confidence interval [CI]: 6.9-11.2) months (p < 0.001). This was 25.7 (90% CI: 21.2-30.3) months in group A (fulvestrant monotherapy). The TTF in group B was 7.2 (90% CI: 5.5-10.4) months. In the post-hoc analysis, the median PFS1 in group B among patients with longer-duration fulvestrant monotherapy (> 1 year) was longer than that of patients with shorter-duration monotherapy (≤ 1 year) (11.3 vs. 7.6 months). No new toxicities were observed.
    CONCLUSION: Our findings suggest that palbociclib plus fulvestrant after disease progression despite fulvestrant monotherapy is potentially safe and effective in patients with HR-positive/HER2-negative advanced MBC.
    Keywords:  Advanced breast cancer; Breast neoplasms; CDK 4/6 inhibitors; Selective estrogen receptor modulators
    DOI:  https://doi.org/10.1007/s10549-023-06911-5
  5. Medicina (Kaunas). 2023 Mar 12. pii: 557. [Epub ahead of print]59(3):
      Background and Objectives: This investigation aimed to determine the impacts of concurrent proton pump inhibitors (PPIs) on progression-free survival (PFS) in patients with hormone receptor-positive and HER2-negative metastatic breast cancer managed with palbociclib or ribociclib as either the initial or subsequent line of therapy option. Materials and Methods: In this retrospective study, patients were classified as "concurrent PPIs" if PPIs were given for at least two-thirds of the palbociclib or ribociclib therapy period, and "no concurrent PPIs" if no PPIs were given during the period of palbociclib or ribociclib therapy. Each patient was also classified as endocrine-sensitive or endocrine-resistant according to the duration of previous endocrine responses. "Concurrent PPIs" and "no concurrent PPIs" groups were compared with each other in terms of PFS. This comparison was performed for both ribociclib and palbociclib groups. Results: The research included 220 patients in total. The PFS of 57 patients on palbociclib using concomitant PPIs was 14.4 months. Among 63 patients using palbociclib without concomitant PPIs, the PFS was 15.8 months. No statistically significant difference was found with PPI use (p = 0.82). Among 29 patients using ribociclib concurrently with PPIs, the PFS was 22.4 months. Among 71 patients using ribociclib without PPIs, the PFS was 20.2 months. No statistically significant difference was found with PPI use (p = 0.40). Conclusion: The results of our investigation showed that concomitant use of the most commonly used PPIs in the study (lansoprazole, pantoprazole, and esomeprazole) with palbociclib or ribociclib did not have any detrimental effects on PFS. Where appropriate, PPIs can be used concurrently with palbociclib and ribociclib. However, the effect of PPIs on cycling-dependent kinase 4/6 inhibitors deserves further investigation.
    Keywords:  drug-drug interactions; metastatic breast cancer; palbociclib; proton pump inhibitors; ribociclib
    DOI:  https://doi.org/10.3390/medicina59030557
  6. Cancers (Basel). 2023 Mar 22. pii: 1908. [Epub ahead of print]15(6):
      BACKGROUND: CDK4/6 inhibitors (CDKi) have improved disease control in hormone-receptor-positive, HER2-negative metastatic breast cancer, but most patients develop progressive disease.METHODS: We asked whether host stromal senescence after CDK4/6 inhibition affects metastatic seeding and growth of CDKi-resistant mammary cancer cells by using the p16-INK-ATTAC mouse model of inducible senolysis.
    RESULTS: Palbociclib pretreatment of naïve mice increased lung seeding of CDKi-resistant syngeneic mammary cancer cells, and this effect was reversed by depletion of host senescent cells. RNA sequencing analyses of lungs from non-tumor-bearing p16-INK-ATTAC mice identified that palbociclib downregulates immune-related gene sets and gene expression related to leukocyte migration. Concomitant senolysis reversed a portion of these effects, including pathway-level enrichment of TGF-β- and senescence-related signaling. CIBERSORTx analysis revealed that palbociclib alters intra-lung macrophage/monocyte populations. Notably, lung metastases from palbociclib-pretreated mice revealed senescent endothelial cells. Palbociclib-treated endothelial cells exhibit hallmark senescent features in vitro, upregulate genes involved with the senescence-associated secretory phenotype, leukocyte migration, and TGF-β-mediated paracrine senescence and induce tumor cell migration and monocyte trans-endothelial invasion in co-culture.
    CONCLUSIONS: These studies shed light on how stromal senescence induced by palbociclib affects lung metastasis, and they describe palbociclib-induced gene expression changes in the normal lung and endothelial cell models that correlate with changes in the tumor microenvironment in the lung metastatic niche.
    Keywords:  CDK4/6 inhibitors; TGF-β; abemaciclib; endothelium; lung metastasis; macrophage; mammary cancer; monocyte; p16-INK-ATTAC; p16INK4A; p21CIP1; palbociclib; senescence; senolytic
    DOI:  https://doi.org/10.3390/cancers15061908
  7. Cancers (Basel). 2023 Mar 20. pii: 1855. [Epub ahead of print]15(6):
      Front-line therapy for advanced and metastatic hormone receptor positive (HR+), HER2 negative (HER-) advanced or metastatic breast cancer (mBC) is endocrine therapy with a CDK4/6 inhibitor (CDK4/6i). The introduction of CDK4/6i has dramatically improved progression-free survival and, in some cases, overall survival. The optimal sequencing of post-front-line therapy must be personalized to patients' overall health and tumor biology. This paper reviews approved next lines of therapy for mBC and available data on efficacy post-progression on CDK4/6i. Given the success of endocrine front-line therapy, there has been an expansion in therapies under clinical investigation targeting the estrogen receptor in novel ways. There are also clinical trials ongoing attempting to overcome CDK4/6i resistance. This paper will review these drugs under investigation, review efficacy data when possible, and provide descriptions of the adverse events reported.
    Keywords:  CDK4/6 inhibitor; HER2 low; SERD; hormone receptor positive; metastatic breast cancer; second line
    DOI:  https://doi.org/10.3390/cancers15061855
  8. Molecules. 2023 Mar 08. pii: 2490. [Epub ahead of print]28(6):
      CDK4/6 and aromatase are prominent targets for breast cancer drug discovery and are involved in abnormal cell proliferation and growth. Although aromatase inhibitors have proven to be effective (for example exemestane, anastrozole, letrozole), resistance to treatment eventually occurs through the activation of alternative signaling pathways, thus evading the antiproliferative effects of aromatase inhibitors. One of the evasion pathways is Cylin D-CDK4/6-Rb signaling that promotes tumor proliferation and resistance to aromatase inhibitors. There is significant evidence that the sequential inhibition of both proteins provides therapeutic benefits over the inhibition of one target. The basis of this study objective is the identification of molecules that are likely to inhibit both CDK4/6 and aromatase by computational chemistry techniques, which need further biochemical studies to confirm. Initially, a structure-based pharmacophore model was constructed for each target to screen the sc-PDB database. Consequently, pharmacophore screening and molecular docking were performed to evaluate the potential lead candidates that effectively mapped both of the target pharmacophore models. Considering abemaciclib (CDK4/6 inhibitor) and exemestane (aromatase inhibitor) as reference drugs, four potential virtual hit candidates (1, 2, 3, and 4) were selected based on their fit values and binding interaction after screening a sc-PDB database. Further, molecular dynamics simulation studies solidify the stability of the lead candidate complexes. In addition, ADMET and DFT calculations bolster the lead candidates. Hence, these combined computational approaches will provide a better therapeutic potential for developing CDK4/6-aromatase dual inhibitors for HR+ breast cancer therapy.
    Keywords:  CDK4/6; MD simulations; anti-breast cancer drug; aromatase; dual inhibitor; molecular docking; structure-based pharmacophore
    DOI:  https://doi.org/10.3390/molecules28062490