The cyclin D-cyclin-dependent kinase (CDK) 4/6-p16-retinoblastoma (Rb) pathway is commonly disrupted in cancer, leading to abnormal cell proliferation. Therapeutics targeting this pathway have ...demonstrated antitumor effects in preclinical and clinical studies. Ribociclib is a selective, orally bioavailable inhibitor of CDK4 and CDK6, which received FDA approval in March 2017 and is set to enter the treatment landscape alongside other CDK4/6 inhibitors, including palbociclib and abemaciclib. Here, we describe the mechanism of action of ribociclib and review preclinical and clinical data from phase I, II, and III trials of ribociclib across different tumor types, within the context of other selective CDK4/6 inhibitors. The pharmacokinetics, pharmacodynamics, safety, tolerability, and clinical responses with ribociclib as a single agent or in combination with other therapies are discussed, and an overview of the broad portfolio of ongoing clinical trials with ribociclib across a wide range of indications is presented. On the basis of the available data, ribociclib has a manageable tolerability profile and therapeutic potential for a variety of cancer types. Its high selectivity makes it an important partner drug for other targeted therapies, and it has been shown to enhance the clinical activity of existing anticancer therapies and delay the development of treatment resistance, without markedly increasing toxicity. Ongoing trials of doublet and triplet targeted therapies containing ribociclib seek to identify optimal CDK4/6-based targeted combination regimens for various tumor types and advance the field of precision therapeutics in oncology.
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Based on promising preclinical data, we conducted a single-arm phase II trial to assess the clinical benefit rate (CBR) of neratinib, defined as complete/partial response (CR/PR) or stable disease ...(SD) ≥24 weeks, in
nonamplified metastatic breast cancer (MBC). Secondary endpoints included progression-free survival (PFS), toxicity, and circulating tumor DNA (ctDNA)
detection.
Tumor tissue positive for
was required for eligibility. Neratinib was administered 240 mg daily with prophylactic loperamide. ctDNA sequencing was performed retrospectively for 54 patients (14 positive and 40 negative for tumor
).
Nine of 381 tumors (2.4%) sequenced centrally harbored
(lobular 7.8% vs. ductal 1.6%;
= 0.026). Thirteen additional
cases were identified locally. Twenty-one of these 22
cases were estrogen receptor positive. Sixteen patients median age 58 (31-74) years and three (2-10) prior metastatic regimens received neratinib. The CBR was 31% 90% confidence interval (CI), 13%-55%, including one CR, one PR, and three SD ≥24 weeks. Median PFS was 16 (90% CI, 8-31) weeks. Diarrhea (grade 2, 44%; grade 3, 25%) was the most common adverse event. Baseline ctDNA sequencing identified the same
in 11 of 14 tumor-positive cases (sensitivity, 79%; 90% CI, 53%-94%) and correctly assigned 32 of 32 informative negative cases (specificity, 100%; 90% CI, 91%-100%). In addition, ctDNA
variant allele frequency decreased in nine of 11 paired samples at week 4, followed by an increase upon progression.
Neratinib is active in
, nonamplified MBC. ctDNA sequencing offers a noninvasive strategy to identify patients with
cancers for clinical trial participation.
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An earlier analysis of this phase 3 trial showed that the addition of a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor to endocrine therapy provided a greater benefit with regard to ...progression-free survival than endocrine therapy alone in premenopausal or perimenopausal patients with advanced hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer. Here we report the results of a protocol-specified interim analysis of the key secondary end point of overall survival.
We randomly assigned patients to receive either ribociclib or placebo in addition to endocrine therapy (goserelin and either a nonsteroidal aromatase inhibitor or tamoxifen). Overall survival was evaluated with the use of a stratified log-rank test and summarized with the use of Kaplan-Meier methods.
A total of 672 patients were included in the intention-to-treat population. There were 83 deaths among 335 patients (24.8%) in the ribociclib group and 109 deaths among 337 patients (32.3%) in the placebo group. The addition of ribociclib to endocrine therapy resulted in significantly longer overall survival than endocrine therapy alone. The estimated overall survival at 42 months was 70.2% (95% confidence interval CI, 63.5 to 76.0) in the ribociclib group and 46.0% (95% CI, 32.0 to 58.9) in the placebo group (hazard ratio for death, 0.71; 95% CI, 0.54 to 0.95; P = 0.00973 by log-rank test). The survival benefit seen in the subgroup of 495 patients who received an aromatase inhibitor was consistent with that in the overall intention-to-treat population (hazard ratio for death, 0.70; 95% CI, 0.50 to 0.98). The percentage of patients who received subsequent antineoplastic therapy was balanced between the groups (68.9% in the ribociclib group and 73.2% in the placebo group). The time from randomization to disease progression during receipt of second-line therapy or to death was also longer in the ribociclib group than in the placebo group (hazard ratio for disease progression or death, 0.69; 95% CI, 0.55 to 0.87).
This trial showed significantly longer overall survival with a CDK4/6 inhibitor plus endocrine therapy than with endocrine therapy alone among patients with advanced hormone-receptor-positive, HER2-negative breast cancer. No new concerns regarding toxic effects emerged with longer follow-up. (Funded by Novartis; MONALEESA-7 ClinicalTrials.gov number, NCT02278120.).
Purpose Metabolic syndrome is associated with an increased risk of cardiovascular disease, type 2 diabetes, and breast cancer recurrence in survivors of breast cancer. This randomized controlled ...trial assessed the effects of a 16-week combined aerobic and resistance exercise intervention on metabolic syndrome, sarcopenic obesity, and serum biomarkers among ethnically diverse, sedentary, overweight, or obese survivors of breast cancer. Methods Eligible survivors of breast cancer (N = 100) were randomly assigned to exercise (n = 50) or usual care (n = 50). The exercise group participated in supervised moderate-to-vigorous-65% to 85% of heart rate maximum-aerobic and resistance exercise three times per week for 16 weeks. Metabolic syndrome z-score (primary outcome), sarcopenic obesity, and serum biomarkers were measured at baseline, postintervention (4 months), and 3-month follow-up (exercise only). Results Participants were age 53 ± 10.4 years, 46% were obese, and 74% were ethnic minorities. Adherence to the intervention was 95%, and postintervention assessments were available in 91% of participants. Postintervention metabolic syndrome z-score was significantly improved in exercise versus usual care (between-group difference, -4.4; 95% CI, -5.9 to -2.7; P < .001). Sarcopenic obesity (appendicular skeletal mass index, P = .001; body mass index, P = .001) and circulating biomarkers, including insulin ( P = .002), IGF-1 ( P = .001), leptin ( P = .001), and adiponectin ( P = .001), were significantly improved postintervention compared with usual care. At 3-month follow-up, all metabolic syndrome variables remained significantly improved compared with baseline in the exercise group ( P < .01). Conclusion Combined resistance and aerobic exercise effectively attenuated metabolic syndrome, sarcopenic obesity, and relevant biomarkers in an ethnically diverse sample of sedentary, overweight, or obese survivors of breast cancer. Our findings suggest a targeted exercise prescription for improving metabolic syndrome in survivors of breast cancer and support the incorporation of supervised clinical exercise programs into breast cancer treatment and survivorship care plans.
Our aim was to examine the association of pretreatment tumor-infiltrating lymphocyte (TIL) count and PD-L1 levels with pathologic complete response (pCR) and assess immune marker changes following ...treatment in tumor specimens from the S0800 clinical trial, which randomized patients to bevacizumab + nab-paclitaxel, followed by doxorubicin/cyclophosphamide (AC) versus two control arms without bevacizumab (varying sequence of AC and nab-paclitaxel). TILs were assessed in 124 pre- and 62 posttreatment tissues (including 59 pairs). PD-L1 was assessed in 120 pre- and 43 posttreatment tissues (including 39 pairs) using the 22C3 antibody. Baseline and treatment-induced immune changes were correlated with pCR and survival using estrogen receptor (ER) and treatment-adjusted logistic and Cox regressions, respectively. At baseline, the mean TIL count was 17.4% (17% had zero TILs, 9% had ≥50% TILs). Posttreatment, mean TIL count decreased to 11% (5% had no TILs, 2% had >50% TILs). In paired samples, the mean TIL change was 15% decrease. Baseline PD-L1 was detected in 43% of cases (
= 5 in tumor cells,
= 29 stroma,
= 18 tumor + stroma). Posttreatment, PD-L1 expression was not significantly lower (33%). Higher baseline TIL count and PD-L1 positivity rate were associated with higher pCR rate even after adjustment for treatment and ER status (
= 0.018). There was no association between TIL counts, PD-L1 expression, and survival due to few events. In conclusion, TIL counts, but not PD-L1 expression, decreased significantly after treatment. Continued PD-L1 expression in some residual cancers raises the possibility that adjuvant immune checkpoint inhibitor therapy could improve survival in this patient population.
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Exercise is an effective strategy to improve quality of life and physical fitness in breast cancer survivors; however, few studies have focused on the early survivorship period, minorities, ...physically inactive and obese women, or tested a combined exercise program and measured bone health. Here, we report the effects of a 16-week aerobic and resistance exercise intervention on patient-reported outcomes, physical fitness, and bone health in ethnically diverse, physically inactive, overweight or obese breast cancer survivors.
One hundred breast cancer survivors within 6 months of completing adjuvant treatment were assessed at baseline, post-intervention, and 3-month follow-up (exercise group only) for physical fitness, bone mineral density, serum concentrations of bone biomarkers, and quality of life. The exercise intervention consisted of moderate-vigorous (65-85% heart rate maximum) aerobic and resistance exercise thrice weekly for 16 weeks. Differences in mean changes for outcomes were evaluated using mixed-model repeated measure analysis.
At post-intervention, the exercise group was superior to usual care for quality of life (between group difference: 14.7, 95% CI: 18.2, 9.7; p < 0.001), fatigue (p < 0.001), depression (p < 0.001), estimated VO
(p < 0.001), muscular strength (p < 0.001), osteocalcin (p = 0.01), and BSAP (p = 0.001). At 3-month follow-up, all patient-reported outcomes and physical fitness variables remained significantly improved compared to baseline in the exercise group (p < 0.01).
A 16-week combined aerobic and resistance exercise program designed to address metabolic syndrome in ethnically-diverse overweight or obese breast cancer survivors also significantly improved quality of life and physical fitness. Our findings further support the inclusion of supervised clinical exercise programs into breast cancer treatment and care.
This trial is registered on ClinicalTrials.gov: NCT01140282 as of June 9, 2010.
Deregulation of the cell cycle machinery is a hallmark of cancer. While CDK4/6 inhibitors are FDA approved (palbociclib) for treating advanced estrogen receptor-positive breast cancer, two major ...clinical challenges remain: (i) adverse events leading to therapy discontinuation and (ii) lack of reliable biomarkers. Here we report that breast cancer cells activate autophagy in response to palbociclib, and that the combination of autophagy and CDK4/6 inhibitors induces irreversible growth inhibition and senescence in vitro, and diminishes growth of cell line and patient-derived xenograft tumours in vivo. Furthermore, intact G1/S transition (Rb-positive and low-molecular-weight isoform of cyclin E (cytoplasmic)-negative) is a reliable prognostic biomarker in ER positive breast cancer patients, and predictive of preclinical sensitivity to this drug combination. Inhibition of CDK4/6 and autophagy is also synergistic in other solid cancers with an intact G1/S checkpoint, providing a novel and promising biomarker-driven combination therapeutic strategy to treat breast and other solid tumours.
Inflammatory breast cancer (IBC), diagnosed clinically, and triple-negative breast cancer (TNBC), diagnosed by molecular receptor status, are the two most aggressive forms of breast cancer, and both ...lack effective targeted therapies. We previously demonstrated involvement of histone deacetylase (HDAC) inhibitor entinostat in regulating apoptosis in IBC and TNBC cells; here, we aimed to identify novel combination therapy candidates.
Potential therapeutic targets were identified by mRNA expression profiling of TNBC and IBC cells treated with entinostat. Drug action and synergism were assessed by
proliferation assays, tumor growth
, and proteomic analyses. Gain/loss-of-expression studies were utilized to functionally validate the role of identified targets in sensitivity of TNBC and IBC cells to combination therapy.
Entinostat induced activity of the oncogenic ERK pathway and expression of proapoptotic NOXA. These are known to stabilize and degrade, respectively, MCL1, an antiapoptotic Bcl-2 protein. In breast cancer patients, high-MCL1/low-NOXA tumor expression correlated significantly with poor survival outcomes. Combination treatment of entinostat with MEK inhibitor pimasertib reduced the growth of TNBC and IBC cells
and inhibited tumor growth
The synergistic action of combination therapy was observed in TNBC and IBC cell lines in which NOXA expression was induced following entinostat treatment. The therapeutic activity depended on induction of mitochondrial cell death pathways initiated by NOXA-mediated MCL1 degradation.
Our preclinical findings provide a rationale for the clinical testing of combination HDAC and MEK pathway inhibition for TNBC and IBC that exhibit elevated baseline tumor MCL1 expression.
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Genomic changes observed across treatment may result from either clonal evolution or geographically disparate sampling of heterogeneous tumors. Here we use computational modeling based on analysis of ...fifteen primary breast tumors and find that apparent clonal change between two tumor samples can frequently be explained by pre-treatment heterogeneity, such that at least two regions are necessary to detect treatment-induced clonal shifts. To assess for clonal replacement, we devise a summary statistic based on whole-exome sequencing of a pre-treatment biopsy and multi-region sampling of the post-treatment surgical specimen and apply this measure to five breast tumors treated with neoadjuvant HER2-targeted therapy. Two tumors underwent clonal replacement with treatment, and mathematical modeling indicates these two tumors had resistant subclones prior to treatment and rates of resistance-related genomic changes that were substantially larger than previous estimates. Our results provide a needed framework to incorporate primary tumor heterogeneity in investigating the evolution of resistance.
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