Clinical and Pharmacologic Differences of CDK4/6 Inhibitors in Breast Cancer.
TL;DR: In this paper, the authors explore the preclinical and pharmacological differences between the three approved agents and help understand the benefits seen with these agents in certain subgroups of patients with metastatic HR positive breast cancer.
Abstract: Targeted therapies such as Cyclin Dependent Kinase 4 and 6 (CDK 4/6) inhibitors have improved the prognosis of metastatic hormone receptor (HR) positive breast cancer by combating the resistance seen with traditional endocrine therapy. The three approved agents currently in the market are palbociclib, ribociclib and abemaciclib. Besides the overall similarities associated with CDK4/6 inhibition, there are differences between the three approved agents that may explain the differences noted in unique clinical scenarios- monotherapy, patients with brain metastases or use in the adjuvant setting. This review article will explore the preclinical and pharmacological differences between the three agents and help understand the benefits seen with these agents in certain subgroups of patients with metastatic HR positive breast cancer.
Citations
More filters
TL;DR: The PALLAS trial as mentioned in this paper showed that the addition of adjuvant palbociclib to standard endocrine therapy alone did not improve outcomes over endocrine treatment alone in patients with early hormone receptor-positive breast cancer.
Abstract: Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor approved for advanced breast cancer. In the adjuvant setting, the potential value of adding palbociclib to endocrine therapy for hormone receptor-positive breast cancer has not been confirmed.In the prospective, randomized, phase III PALLAS trial, patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative early breast cancer were randomly assigned to receive 2 years of palbociclib (125 mg orally once daily, days 1-21 of a 28-day cycle) with adjuvant endocrine therapy or adjuvant endocrine therapy alone (for at least 5 years). The primary end point of the study was invasive disease-free survival (iDFS); secondary end points were invasive breast cancer-free survival, distant recurrence-free survival, locoregional cancer-free survival, and overall survival.Among 5,796 patients enrolled at 406 centers in 21 countries worldwide over 3 years, 5,761 were included in the intention-to-treat population. At the final protocol-defined analysis, at a median follow-up of 31 months, iDFS events occurred in 253 of 2,884 (8.8%) patients who received palbociclib plus endocrine therapy and in 263 of 2,877 (9.1%) patients who received endocrine therapy alone, with similar results between the two treatment groups (iDFS at 4 years: 84.2% v 84.5%; hazard ratio, 0.96; CI, 0.81 to 1.14; P = .65). No significant differences were observed for secondary time-to-event end points, and subgroup analyses did not show any differences by subgroup. There were no new safety signals for palbociclib in this trial.At this final analysis of the PALLAS trial, the addition of adjuvant palbociclib to standard endocrine therapy did not improve outcomes over endocrine therapy alone in patients with early hormone receptor-positive breast cancer.
55 citations
TL;DR: In this article , an integrated in-silico approach followed by steered molecular dynamics (SMD) simulations to identify molecules that can be developed into novel CDK4/6 inhibitors was presented.
11 citations
TL;DR: The present studies were performed to define its biology in estrogen receptor positive breast cancer cells and to determine whether it interacted with palbociclib to enhance tumor cell killing and to enhance autophagosome formation and autophagic flux.
Abstract: GZ17-6.02 is presently undergoing clinical evaluation in solid tumors and lymphoma. The present studies were performed to define its biology in estrogen receptor positive breast cancer cells and to determine whether it interacted with palbociclib to enhance tumor cell killing. GZ17-6.02 interacted in an additive fashion with palbociclib to kill ER+ breast cancer cells. GZ17-6.02 and palbociclib cooperated to inactivate mTOR and AKT and to activate ULK1 and PERK. The drugs interacted to increase the expression of FAS-L and BAX, and to decrease the levels of MCL1, the estrogen receptor, and HDACs 1–3. Palbociclib activated ERBB3, an effect blocked by GZ17-6.02. GZ17-6.02 and palbociclib interacted to increase the expression of multiple toxic BH3 domain proteins and to reduce MCL1 and BCL-XL expression. Knock down of FAS-L reduced the lethality of [GZ17-6.02 + palbociclib]. GZ17-6.02 and palbociclib interacted to enhance autophagosome formation and autophagic flux. Knock down of Beclin1, ATG5, BAG3, eIF2α, toxic BH3 domain proteins or CD95 significantly reduced drug combination lethality. GZ17-6.02 and palbociclib increased the expression of Beclin1 and ATG5, effects blocked by knock down of eIF2α. The drugs also increased the phosphorylation of the AMPK and ATG13, effects blocked by knock down of ATM. Knock down of ATM or the AMPK, or expression of activated mTOR significantly reduced the abilities of GZ17-6.02 and palbociclib to enhance autophagosome formation and autophagic flux.
7 citations
20 Apr 2022
TL;DR: In this article , the authors discuss what the most recent insights mean for clinical trial design, and propose clinical considerations and strategies that may exploit the full immunotherapeutic potential of CDK4/6 inhibitors.
Abstract: CDK4/6 inhibitors (CDK4/6i) were developed as a cancer therapeutic on the basis of their tumor-intrinsic cytostatic potential, but have since demonstrated profound activity as immunomodulatory agents. While currently approved to treat hormone receptor-positive breast cancer, these inhibitors are under investigation in clinical trials as treatments for a range of cancer types, including melanoma. Melanoma is a highly immunogenic cancer, and has always been situated at the forefront of cancer immunotherapy development. Recent revelations into the immunotherapeutic activity of CDK4/6i, therefore, have significant implications for the utility of these agents as melanoma therapies. In recent studies, we and others have proven the immunomodulatory effects of CDK4/6i to be multifaceted and complex. Among the most notable effects, CDK4/6 inhibition induces transcriptional reprogramming in both tumor cells and immune cells to enhance tumor cell immunogenicity, promote an immune-rich tumor microenvironment, and skew T cell differentiation into a stem-like phenotype that is more amenable to immune checkpoint inhibition. However, in some contexts, the specific immunomodulatory effects of CDK4/6i may impinge on anti-tumor immunity. For example, CDK4/6 inhibition restricts optimal T cells expansion, and when used in combination with BRAF/MEK-targeted therapies, depletes immune-potentiating myeloid subsets from the tumor microenvironment. We propose that such effects, both positive and negative, may be mitigated or exacerbated by altering the CDK4/6i dosing regimen. Here, we discuss what the most recent insights mean for clinical trial design, and propose clinical considerations and strategies that may exploit the full immunotherapeutic potential of CDK4/6 inhibitors.
7 citations
TL;DR: In this article , the authors evaluated the treatment-emergent adverse events (TEAEs) of abemaciclib/placebo in combination with fulvestrant (MONARCH 2; M2) or non-steroidal aromatase inhibitors (M3).
Abstract: Our objective was to gain a better understanding of the safety of abemaciclib in Japanese patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer.Treatment-emergent adverse events (TEAEs) were assessed in pooled Japanese subpopulation data from two phase 3 studies assessing abemaciclib/placebo in combination with fulvestrant (MONARCH 2; M2) or non-steroidal aromatase inhibitors (MONARCH 3; M3). For common, clinically relevant TEAEs, event characteristics and management were summarized by study.In the Japanese safety subpopulation (abemaciclib: N=101; placebo: N=46), all patients experienced ≥1 TEAE (Grade ≥ 3: abemaciclib, 71.3%; placebo, 23.9%; no Grade 5). Clinically relevant TEAEs that were more frequent in abemaciclib-treated Japanese patients compared to the overall safety populations included diarrhea (any grade, 95.0%; Grade ≥ 3, 12.9%), neutropenia (any grade, 75.2%; Grade 3-4, 35.6%), increased alanine aminotransferase (ALT; any grade, 39.6%; Grade 3-4, 14.9%), and increased aspartate aminotransferase (AST; any grade, 37.6%; Grade 3-4, 8.9%). Diarrhea was Grade ≤3 and successfully managed with medications (≥87%) and dose reductions (≤25%) and/or omissions (≤23.3%). Most Grade ≥2 diarrhea occurred in the first treatment cycle, declining thereafter. Neutropenia, the most common Grade ≥3 TEAE in abemaciclib-treated Japanese patients, was generally manageable with dose omissions (M2: 42.0%; M3: 23.1%) and/or reductions (M2: 16%; M3: 15.4%). Neutrophil counts plateaued after Cycle 2, recovering to pretreatment levels after discontinuation of abemaciclib. Hepatic events were managed with medication (≤21%) and dose adjustments (≤33.3%), with most Grade ≥2 events occurring in early treatment cycles. Discontinuation of any study treatment in Japanese patients occurred more frequently due to increased ALT/AST (M2: 9.1%/10.5%; M3: 16.7%/10.5%) compared with diarrhea (M2: 0%; M3: 2.8%) or neutropenia (M2: 0%; M3: 3.8%).Abemaciclib was well tolerated in Japanese patients in MONARCH 2 and MONARCH 3, with common, clinically relevant TEAEs manageable with appropriate interventions.
6 citations
References
More filters
TL;DR: Among patients with previously untreated ER-positive, HER2-negative advanced breast cancer, palbociclib combined with letrozole resulted in significantly longer progression-free survival than that with let rozole alone, although the rates of myelotoxic effects were higher with palbokiclib-letrozoles.
Abstract: BackgroundA phase 2 study showed that progression-free survival was longer with palbociclib plus letrozole than with letrozole alone in the initial treatment of postmenopausal women with estrogen-receptor (ER)–positive, human epidermal growth factor receptor 2 (HER2)–negative advanced breast cancer. We performed a phase 3 study that was designed to confirm and expand the efficacy and safety data for palbociclib plus letrozole for this indication. MethodsIn this double-blind study, we randomly assigned, in a 2:1 ratio, 666 postmenopausal women with ER-positive, HER2-negative breast cancer, who had not had prior treatment for advanced disease, to receive palbociclib plus letrozole or placebo plus letrozole. The primary end point was progression-free survival, as assessed by the investigators; secondary end points were overall survival, objective response, clinical benefit response, patient-reported outcomes, pharmacokinetic effects, and safety. ResultsThe median progression-free survival was 24.8 months (95...
1,737 citations
TL;DR: Palbociclib (PD-0332991) is an oral, small-molecule inhibitor of cyclin-dependent kinases (CDKs) 4 and 6 with preclinical evidence of growth-inhibitory activity in oestrogen receptor-positive breast cancer cells and synergy with anti-oestrogens as mentioned in this paper.
Abstract: Summary Background Palbociclib (PD-0332991) is an oral, small-molecule inhibitor of cyclin-dependent kinases (CDKs) 4 and 6 with preclinical evidence of growth-inhibitory activity in oestrogen receptor-positive breast cancer cells and synergy with anti-oestrogens. We aimed to assess the safety and efficacy of palbociclib in combination with letrozole as first-line treatment of patients with advanced, oestrogen receptor-positive, HER2-negative breast cancer. Methods In this open-label, randomised phase 2 study, postmenopausal women with advanced oestrogen receptor-positive and HER2-negative breast cancer who had not received any systemic treatment for their advanced disease were eligible to participate. Patients were enrolled in two separate cohorts that accrued sequentially: in cohort 1, patients were enrolled on the basis of their oestrogen receptor-positive and HER2-negative biomarker status alone, whereas in cohort 2 they were also required to have cancers with amplification of cyclin D1 ( CCND1 ), loss of p16 (INK4A or CDKN2A), or both. In both cohorts, patients were randomly assigned 1:1 via an interactive web-based randomisation system, stratified by disease site and disease-free interval, to receive continuous oral letrozole 2·5 mg daily or continuous oral letrozole 2·5 mg daily plus oral palbociclib 125 mg, given once daily for 3 weeks followed by 1 week off over 28-day cycles. The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. Accrual to cohort 2 was stopped after an unplanned interim analysis of cohort 1 and the statistical analysis plan for the primary endpoint was amended to a combined analysis of cohorts 1 and 2 (instead of cohort 2 alone). The study is ongoing but closed to accrual; these are the results of the final analysis of progression-free survival. The study is registered with the ClinicalTrials.gov, number NCT00721409. Findings Between Dec 22, 2009, and May 12, 2012, we randomly assigned 165 patients, 84 to palbociclib plus letrozole and 81 to letrozole alone. At the time of the final analysis for progression-free survival (median follow-up 29·6 months [95% CI 27·9–36·0] for the palbociclib plus letrozole group and 27·9 months [25·5–31·1] for the letrozole group), 41 progression-free survival events had occurred in the palbociclib plus letrozole group and 59 in the letrozole group. Median progression-free survival was 10·2 months (95% CI 5·7–12·6) for the letrozole group and 20·2 months (13·8–27·5) for the palbociclib plus letrozole group (HR 0·488, 95% CI 0·319–0·748; one-sided p=0·0004). In cohort 1 (n=66), median progression-free survival was 5·7 months (2·6–10·5) for the letrozole group and 26·1 months (11·2–not estimable) for the palbociclib plus letrozole group (HR 0·299, 0·156–0·572; one-sided p Interpretation The addition of palbociclib to letrozole in this phase 2 study significantly improved progression-free survival in women with advanced oestrogen receptor-positive and HER2-negative breast cancer. A phase 3 trial is currently underway. Funding Pfizer.
1,466 citations
TL;DR: Tumour cells undergo uncontrolled proliferation, yet tumours most often originate from adult tissues, in which most cells are quiescent, so the proliferative advantage of tumour cells arises from their ability to bypass quiescence.
Abstract: Tumour cells undergo uncontrolled proliferation, yet tumours most often originate from adult tissues, in which most cells are quiescent. So, the proliferative advantage of tumour cells arises from their ability to bypass quiescence. This can be due to increased mitogenic signalling and/or alterations that lower the threshold required for cell-cycle commitment. Understanding the molecular mechanisms that underlie this commitment should provide important insights into how normal cells become tumorigenic and how new anticancer strategies can be devised.
1,429 citations
TL;DR: How CDK inhibitors with high selectivity (particularly for both CDK4 and CDK6), in combination with patient stratification, have resulted in more substantial clinical activity is discussed.
Abstract: Cancer represents a pathological manifestation of uncontrolled cell division; therefore, it has long been anticipated that our understanding of the basic principles of cell cycle control would result in effective cancer therapies. In particular, cyclin-dependent kinases (CDKs) that promote transition through the cell cycle were expected to be key therapeutic targets because many tumorigenic events ultimately drive proliferation by impinging on CDK4 or CDK6 complexes in the G1 phase of the cell cycle. Moreover, perturbations in chromosomal stability and aspects of S phase and G2/M control mediated by CDK2 and CDK1 are pivotal tumorigenic events. Translating this knowledge into successful clinical development of CDK inhibitors has historically been challenging, and numerous CDK inhibitors have demonstrated disappointing results in clinical trials. Here, we review the biology of CDKs, the rationale for therapeutically targeting discrete kinase complexes and historical clinical results of CDK inhibitors. We also discuss how CDK inhibitors with high selectivity (particularly for both CDK4 and CDK6), in combination with patient stratification, have resulted in more substantial clinical activity.
1,276 citations
University of Texas MD Anderson Cancer Center1, Tel Aviv University2, Sarah Cannon Research Institute3, Netherlands Cancer Institute4, Sheba Medical Center5, Duke University6, University of Paris-Sud7, Harvard University8, University of Ulm9, Tom Baker Cancer Centre10, Vanderbilt University11, University of Edinburgh12, University of Franche-Comté13, Curtin University14, University of Southern Denmark15, Praxis16, University of Tübingen17, University of Oslo18, National Yang-Ming University19, Novartis20
TL;DR: Among patients receiving initial systemic treatment for HR-positive, HER2-negative advanced breast cancer, the duration of progression-free survival was significantly longer among those receiving ribociclib plus letrozole than among those received placebo plus let rozole, with a higher rate of myelosuppression in the ribocIClib group.
Abstract: BackgroundThe inhibition of cyclin-dependent kinases 4 and 6 (CDK4/6) could potentially overcome or delay resistance to endocrine therapy in advanced breast cancer that is positive for hormone receptor (HR) and negative for human epidermal growth factor receptor 2 (HER2). MethodsIn this randomized, placebo-controlled, phase 3 trial, we evaluated the efficacy and safety of the selective CDK4/6 inhibitor ribociclib combined with letrozole for first-line treatment in 668 postmenopausal women with HR-positive, HER2-negative recurrent or metastatic breast cancer who had not received previous systemic therapy for advanced disease. We randomly assigned the patients to receive either ribociclib (600 mg per day on a 3-weeks-on, 1-week-off schedule) plus letrozole (2.5 mg per day) or placebo plus letrozole. The primary end point was investigator-assessed progression-free survival. Secondary end points included overall survival, overall response rate, and safety. A preplanned interim analysis was performed on Januar...
1,232 citations