Overall Survival with Ribociclib plus Fulvestrant in Advanced Breast Cancer

Discovery of novel quinoline scaffold selective estrogen receptor degraders (SERDs) for treatment of ER positive breast cancer with enhanced antiproliferative bioactivity through immunogenic cell death (ICD) effects

Combination therapy proven to be an effective therapeutic approach for estrogen receptor (ER)-positive breast cancer. Currently, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors are combined with aromatase inhibitors (AIs) or selective estrogen receptor degraders (SERDs) as first-line therapy for advanced ER-positive breast cancer. Herein, a new family of quinoline scaffold SERDs was synthesized and evaluated in MCF-7 cells. Among them, compounds 18j and 24d exhibited remarkable MCF-7 inhibition, both alone and in combination with ribociclib (CDK4/6 inhibitor), in vitro and in vivo. Meanwhile, compounds 18j and 24d effectively degraded ER and inhibited ER downstream signaling pathways. Interestingly, compounds 18j and 24d induced endoplasmic reticulum stress (ERS) and triggered immunogenic cell death (ICD) via damage-associated molecular patterns (DAMPs) in MCF-7 cells. These findings highlight the immune-related and enhanced antiproliferative effects of oral SERDs in ER positive breast cancer treatment.

Therapeutic Monitoring of Palbociclib, Ribociclib, Abemaciclib, M2, M20, and Letrozole in Human Plasma: A Novel LC-MS/MS Method

BACKGROUND

Therapeutic drug monitoring (TDM) using cyclin-dependent kinase inhibitors (CDK4/6is) is a novel approach for optimizing treatment outcomes. Currently, palbociclib, ribociclib, and abemaciclib are the available CDK4/6is and are primarily coadministered with letrozole. This study aimed to develop and validate an LC-MS/MS method for the simultaneous analysis of CDK4/6is, 2 active metabolites of abemaciclib (M2 and M20), and letrozole in human plasma for use in TDM studies.

METHODS

Sample pretreatment comprised protein precipitation with methanol and dilution of the supernatant with an aqueous mobile phase. Chromatographic separation was achieved using a reversed-phase XBridge BEH C18 column (2.5 μm, 3.0 × 75 mm XP), with methanol serving as the organic mobile phase and pyrrolidine-pyrrolidinium formate (0.005:0.005 mol/L) buffer (pH 11.3) as the aqueous mobile phase. A triple quadrupole mass spectrometer was used for the detection, with the ESI source switched from negative to positive ionization mode and the acquisition performed in multiple reaction monitoring mode.

RESULTS

The complete validation procedure was successfully performed in accordance with the latest regulatory guidelines. The following analytical ranges (ng/mL) were established for the tested compounds: 6-300, palbociclib and letrozole; 120-6000, ribociclib; 40-800, abemaciclib; and 20-400, M2 and M20. All results met the acceptance criteria for linearity, accuracy, precision, selectivity, sensitivity, matrix effects, and carryover. A total of 85 patient samples were analyzed, and all measured concentrations were within the validated ranges. The percent difference for the reanalyzed samples ranged from -11.2% to 7.0%.

CONCLUSIONS

A simple and robust LC-MS/MS method was successfully validated for the simultaneous quantification of CDK4/6is, M2, M20, and letrozole in human plasma. The assay was found to be suitable for measuring steady-state trough concentrations of the analytes in patient samples.

The NEOLETRIB trial: neoadjuvant treatment with Letrozole and Ribociclib in ER-positive, HER2-negative breast cancer

Chemotherapy is used as neoadjuvant therapy for all subgroups of breast cancer, including ER-positive, and HER2-negative cases. However, studies have suggested that using aromatase inhibitors combined with CDK4/6-inhibitors might be an appropriate alternative in selected patients. Thus, the NEOLETRIB trial evaluates the response of ER-positive, HER2-negative luminal A/B breast cancer to the combination of letrozole and ribociclib in the neoadjuvant setting. Comprehensive molecular biology procedures, including sequential single-cell RNA-sequencing of tumor biopsies, are performed during 6 months of treatment with extensive biobanking of blood samples, tumor biopsies and gut microbiome specimens. Our findings will hopefully contribute to an improved selection of patients who may benefit from this drug combination and give new insights into the intra-tumoral changes during this treatment.Trial registration number: NCT05163106 (ClinicalTrials.gov).

The Impact of Previous Therapy on Overall-Survival in Registration Clinical Trials for 1st Line Metastatic Breast Cancer

AIM

To explore the impact of previous treatment on the efficacy of investigational new drugs in registration trials for 1st line metastatic breast cancer (MBC).

METHODS

Thirteen US Food and Drug Administration (FDA) approved indications for 1st line MBC between 1/2000-12/2023 were identified and their supporting publications were searched in the ClinicalTrials.gov and Google Scholar. Where available, hazard ratios (HRs) and 95% confidence intervals (CI) for overall-survival (OS) were pooled into meta-analysis and the difference in the magnitude of OS benefit between treatment naïve and previously treated patients was analyzed.

RESULTS

There was no difference in the magnitude of OS benefit between treatment-naïve and previously treated patients (HR=0.72 versus 0.80,p for difference=0.25). In indications for triple-negative BC, treatment-naïve patients had higher magnitude of OS benefit compared to previously treated patients (HR=0.53 versus 0.81,p=0.03). In indications for luminal disease, the magnitude of benefit was comparable between the subgroups.

CONCLUSIONS

In trials supporting 1st line therapy for TNBC the magnitude of benefit is significantly higher in treatment naïve compared to previously treated patients. Our findings may represent a previously unrecognized bias, potentially over-estimating the benefit of triple-negative BC new drugs.

Clinical impact of drug-drug interactions on abemaciclib in the real-world experience of AB-ITALY study

Abemaciclib demonstrated clinical benefit in women affected by HR+/HER2- advanced breast cancer (aBC). Drug-drug interactions (DDIs) can lead to reduced treatment efficacy or increased toxicity. This retro-prospective study aimed to evaluate outcomes, DDIs' impact, and toxicities of abemaciclib combined with endocrine therapy in a real-world setting. Patients from 12 referral Italian hospitals with HR+/HER2- aBC who received abemaciclib were included. Clinical data about comorbidities, concurrent medications, outcomes, and adverse events (AE) were collected. Drug-PIN® (Personalized Interactions Network) is a tool recognizing the role of multiple interactions between active and/or pro-drug forms combined with biochemical and demographic patient data. The software was used to define the Drug-PIN score and Drug-PIN tier (green, yellow, dark yellow, and red) for each patient. Univariate and multivariate analyses were performed to identify predictors of patients' PFS or toxicity. One hundred seventy-three patients were included. 13% of patients had >75years. The overall response rate (ORR) was 63%. The general population's median PFS (mPFS) was 22 months (mo), while mOS were not reached. Patients treated with abemaciclib in combination with AI and fulvestrant had a mPFS of 36 and 19 mo, respectively. The most common toxicities were diarrhea, asthenia, and neutropenia detected in 63%,49%, and 49% of patients. The number of concomitant medications and comorbidities were not associated with survival outcomes (22 vs 17 mo, p = 0.068, p = 0.99). Drug-PIN tier from dark yellow to red and Drug-PIN score >12 were associated with shorter PFS compared to no/low-risk DDIs and score <12 (15 vs 23, p = 0.005, p = 0.0017). Drug interaction was confirmed as an independent biomarker in a multivariate model (p = 0.02). No difference in any grade AE, severe toxicities, and diarrhea were detected among different age subgroups. No association was found between Drug-PIN score or Drug-PIN tier and overall toxicity (p = 0.44), severe AEs (p = 0.11), or drug reduction (p = 0.27). The efficacy and safety of abemaciclib plus ET were confirmed in a real-world setting, even in the elderly population and patients with comorbidities. Evaluation of DDIs with Drug-PIN appears to be an independent predictor of PFS.

Synergistic Enhancement of Antitumor Effects by Combining Abemaciclib with Desipramine

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, including abemaciclib, have been approved for the treatment of hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced, and metastatic breast cancer. Despite the high therapeutic efficacy of CDK4/6 inhibitors, they are associated with various adverse effects, including potentially fatal interstitial lung disease. Therefore, a combination of CDK4/6 inhibitors with letrozole or fulvestrant has been attempted but has demonstrated limitations in reducing adverse effects, highlighting the need to develop new combination therapies. This study proposes a combination strategy using CDK4/6 inhibitors and tricyclic antidepressants to enhance the therapeutic outcomes of these inhibitors while reducing their side effects. The therapeutic efficacies of abemaciclib and desipramine were tested in different cancer cell lines (H460, MCF7, and HCT-116). The antitumor effects of the combined abemaciclib and desipramine treatment were evaluated in a xenograft colon tumor model. In vitro cell studies have shown the synergistic anticancer effects of combination therapy in the HCT-116 cell line. The combination treatment significantly reduced tumor size compared with control or single treatment without causing apparent toxicity to normal tissues. Although additional in vivo studies are necessary, this study suggests that the combination therapy of abemaciclib and desipramine may represent a novel therapeutic approach for treating solid tumors.

Efficacy and safety of neoadjuvant therapy for HR-positive/HER2-negative early breast cancer: a Bayesian network meta-analysis

BACKGROUND

Neoadjuvant treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) breast cancer is controversial and requires a comprehensive analysis for optimal therapy assessment. Therefore, a two-step Bayesian network meta-analysis (NMA) was performed to compare the efficacy and safety of different neoadjuvant regimens.

RESEARCH DESIGN AND METHODS

Phase II/III randomized clinical trials comparing various neoadjuvant therapies for HR+/HER2- breast cancer were included. NMA and pairwise meta-analyses were conducted using Stata (version 14), R (version 4.2.3), and Review Manager 5.4.

RESULTS

Twenty-eight studies (5,625 patients) were eligible. NMA of objective response rate (ORR) indicated the highest SUCRA for chemotherapy (CT) and chemotherapy with anthracycline (CT(A)). Pathologic complete response (PCR) NMA demonstrated significant PCR improvement with chemotherapy regimens containing programmed cell death protein-1 and programmed cell death ligand-1 inhibitors (PD-1i/PD-L1i) and poly ADP-ribose polymerase inhibitors (PARPi). Combined analysis considering both the ORR and safety highlighted CT(A)'s efficacy and toxicity balance.

CONCLUSIONS

CT(A) and CT showed improved ORR compared with alternative regimens. CT(A) combined with PD-1/PD-L1 or PARP inhibitors significantly increased PCR rates. Comprehensive assessment of both ORR and safety indicated that CT(A) represents an optimal neoadjuvant therapy for HR+/HER2- breast cancer, whereas AI + CDK4/6 inhibitors rank solely behind chemotherapy.

REGISTRATION

PROSPERO Registration: CRD42024538948. International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) registration number INPLASY202440092.

First-line therapy with palbociclib in patients with advanced HR+/HER2- breast cancer: The real-life study PALBOSPAIN

PURPOSE

To evaluate the efficacy and safety of first-line therapy with palbociclib in a Spanish cohort treated after palbociclib approval.

METHODS

PALBOSPAIN is an observational, retrospective, multicenter study evaluating real-world patterns and outcomes with 1 L palbociclib in men and women (any menopausal status) with advanced HR+/HER2- BC diagnosed between November 2017 and November 2019. The primary endpoint was real-world progression-free survival (rw-PFS). Secondary endpoints included overall survival (OS), the real-world response rate (rw-RR), the clinical benefit rate, palbociclib dose reduction, and safety.

RESULTS

A total of 762 patients were included. The median rw-PFS and OS were 24 months (95% CI 21-27) and 42 months (40-not estimable [NE]) in the whole population, respectively. By cohort, the median rw-PFS and OS were as follows: 28 (95% CI 23-39) and 44 (95% CI 38-NE) months in patients with de novo metastatic disease, 13 (95% CI 11-17) and 36 months (95% CI 31-41) in patients who experienced relapse < 12 months after the end of ET, and 31 months (95% CI 26-37) and not reached (NR) in patients who experienced relapse > 12 months after the end of ET. rw-PFS and OS were longer in patients with oligometastasis and only one metastatic site and those with non-visceral disease. The most frequent hematologic toxicity was neutropenia (72%; grade ≥ 3: 52.5%), and the most common non-hematologic adverse event was asthenia (38%).

CONCLUSION

These findings, consistent with those from clinical trials, support use of palbociclib plus ET as 1 L for advanced BC in the real-world setting, including pre-menopausal women and men.

TRIAL REGISTRATION NUMBER

NCT04874025 (PALBOSPAIN). Date of registration: 04/30/2021 retrospectively registered.

First- vs second-line CDK 4/6 inhibitor use for patients with hormone receptor positive, human epidermal growth-factor receptor-2 negative, metastatic breast cancer in the real world setting

PURPOSE

To compare CDK4/6 inhibitor (CDK4/6i) with endocrine therapy (ET) in the first- versus second-line setting for treatment of hormone receptor positive (HR+), HER2 negative, metastatic breast cancer (MBC) using real-world evidence.

METHODS

Patients with HR+, HER2 negative MBC, diagnosed between 2/3/2015 and 11/2/2021 and having ≥ 3 months follow-up were identified from the nationwide electronic health record-derived Flatiron Health de-identified database. Treatment cohorts included: (1) first-line ET with a CDK 4/6i (1st-line CDK4/6i) versus (2) first-line ET alone followed by second-line ET with a CDK4/6i (2nd-line CDK4/6i). Differences in baseline characteristics were tested using chi-square tests and two-sample t-tests. Time to third-line therapy, time to start of chemotherapy, and overall survival were compared using Kaplan-Maier method.

RESULTS

The analysis included 2771 patients (2170 1st-line CDK4/6i and 601 2nd-line CDK4/6i). Patients receiving 1st-line CDK4/6i were younger (75% vs 68% < 75 years old, p = 0.0001), less likely uninsured or not having insurance status documented (10% vs. 13%, p = 0.04), of better performance status (50% vs 43% with ECOG 0, p = 0.03), and more likely to have de novo MBC (36% vs. 24%, p < 0.001). Time to third-line therapy (49 vs 22 months, p < 0.001) and time to chemotherapy (68 vs 41 months, p < 0.001) were longer in those receiving first-line CDK4/6i. Overall survival (54 vs 49 months, p = 0.33) was similar between groups.

CONCLUSION

Use of CDK4/6i with first-, vs second-, line ET was associated with longer time to receipt of 3rd-line therapy and longer time to receipt of chemotherapy.

Who still needs surgical staging of the axilla for invasive breast cancer?

Sentinel lymphadenectomy may be safely omitted for postmenopausal patients with low-risk estrogen-receptor-positive cancers who have a negative pretreatment axillary ultrasound. Surgical staging should still be done for patients who are premenopausal or postmenopausal with high-risk estrogen receptor-positive cancers, for those having neoadjuvant chemotherapy, or those with estrogen-receptor-negative or human epidermal growth factor receptor-positive cancers.

Novel Treatment Strategies for Hormone Receptor (HR)-Positive, HER2-Negative Metastatic Breast Cancer

Estrogen receptor (ER)-positive breast cancer (BC) is the most common BC subtype. Endocrine therapy (ET) targeting ER signaling still remains the mainstay treatment option for hormone receptor (HR)-positive BC either in the early or in advanced setting, including different strategies, such as the suppression of estrogen production or directly blocking the ER pathway through SERMs-selective estrogen receptor modulators-or SERDs-selective estrogen receptor degraders. Nevertheless, the development of de novo or acquired endocrine resistance still remains challenging for oncologists. The use of novel ET combined with targeted drugs, such as cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, has significantly improved long-term outcome rates, thus changing the therapeutic algorithm for metastatic BC (MBC) and recently the therapeutic strategy in the adjuvant setting for early high-risk BC. Eluding the resistance to CDK4/6 inhibitors combined with ET is currently an unmet medical need, and there is disagreement concerning the best course of action for patients who continue to progress after this combination approach. Genetic changes in the tumor along its growth uncovered by genomic profiling of recurrent and/or metastatic lesions through tumor and/or liquid biopsies may predict the response or resistance to specific agents, suggesting the best therapeutic strategy for each patient by targeting the altered ER-dependent pathway (novel oral SERDs and a new generation of anti-estrogen agents) or alternative ER-independent signaling pathways such as PI3K/AKT/mTOR or tyrosine kinase receptors (HER2 mutations or HER2 low status) or by inhibiting pathways weakened through germline BRCA1/2 mutations. These agents are being investigated as single molecules and in combination with other target therapies, offering promising weapons to overcome or avoid treatment failure and propose increasingly more personalized treatment approaches. This review presents novel insights into ET and other targeted therapies for managing metastatic HR+/HER2- BC by exploring potential strategies based on clinical evidence and genomic profiling following the failure of the CDK4/6i and ET combination.

Quantitative evaluation of the efficacy and safety profiles of two types of targeted inhibitors combined with endocrine therapy in ER+/HER2- metastatic breast cancer

PURPOSE

The aim of this study was to quantitatively compare the efficacy and safety of CDK4/6 inhibitors and PI3K/AKT/mTOR inhibitors for ER+/HER2- metastatic breast cancer.

METHODS

A parametric survival function was used to analyze the time course of overall survival (OS) and progression-free survival (PFS). The objective response rate (ORR) and the incidence of any grade and grade 3-4 adverse events were summarized using the random-effects model of a single-arm meta-analysis.

RESULTS

This study included 44 arms from 48 publications, with a total sample size of 7881 patients. Our study revealed that CDK4/6 inhibitors had a median OS of 40.7 months, a median PFS of 14.8 months, and an ORR of 40%, whereas PI3K/AKT/mTOR inhibitors had a median OS of 29.8 months, a median PFS of 8.3 months, and an ORR of 20%. Additionally, this study also found that the proportion of patients with visceral metastases and specific endocrine therapy used in combination significantly impact OS and PFS. In terms of adverse events, CDK4/6 inhibitors exhibited a relatively high incidence of hematological adverse events.

CONCLUSION

Our study provides solid quantitative evidence for the first-line recommendation of CDK4/6 inhibitors combined with endocrine therapy for ER+/HER2- metastatic breast cancer in clinical guidelines.

Beyond the median: Estimating survival times for patients starting endocrine therapy for estrogen receptor-positive, metastatic breast cancer from recent randomized trials

AIM

To estimate scenarios for survival for patients with estrogen receptor (ER) positive, metastatic breast cancer (MBC) and to help communicate prognosis to patients starting endocrine therapy (ET) METHODS: We searched for randomized trials of ET for ER-positive MBC and extracted the following percentiles (representative survival scenarios) from each overall survival (OS) curve: 90th (worst-case), 75th (lower-typical), 50th (median), 25th (upper-typical), and 10th (best-case). We then assessed the accuracy of estimating these percentiles for each OS curve by multiplying the median OS by four simple multiples: 0.25 (to estimate the 90th percentile), 0.5 (75th), 2 (25th), and 3 (10th). Estimates were deemed accurate if it fell within 0.75-1.33 times the actual value.

RESULTS

We identified 25 trials with 10,566 patients. The median OS (interquartile range) was: 61.3 months (53.4-64.8) for first-line ET with cyclin-dependant kinase 4/6 inhibitors (four treatment groups); 42.6 months (40.9-50.4) for first-line ET alone (21 treatment groups) and 29.2 months (24.8-33.4) for subsequent line ET (19 treatment groups). Simple multiples of the median OS accurately estimated the 90th percentile in 80%; 75th percentile in 93%; and 25th percentile in 76% of curves. The 10th percentile was only available for four OS curves and could not be evaluated.

CONCLUSION

Simple multiples of the median OS are a helpful and accurate method to assist in estimating and discussing scenarios for survival for MBC patients starting ET. Longer follow-up of trials is required to help clinicians estimate the best-case scenario.

Comparative efficacy and safety of CDK4/6 inhibitors combined with endocrine therapies for HR+/HER2-breast cancer: Systematic review and network meta-analysis

Background

In recent years, the combination of targeted drugs, such as Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, with endocrine therapy (ET), has emerged as a new research focus in the treatment of hormone receptor-positive (HR+) human epidermal growth factor receptor 2 negative (HER2-) breast cancer. This network meta-analysis aimed to systematically evaluate the efficacy and safety of CDK4/6 inhibitors combined with ET for HR+/HER2-breast cancer.

Methods

A systematic search was conducted across PubMed, Web of Science, Cochrane Library, and GeenMedical databases to identify randomized controlled trials investigating the use of CDK4/6 inhibitors in combination with endocrine therapy for the treatment of HR+/HER2-breast cancer. The search period spanned from the inception of each database up to February 29, 2024. Data analysis was conducted using Stata 14.0 and R 4.1.0 software.

Results

A total of 20 randomized controlled trials (RCTs) were included in this study, investigating the effectiveness of four CDK4/6 inhibitors-Abemaciclib, Dalpiciclib, Ribociclib, and Palbociclib-when combined with ET for the treatment of HR+/HER2-breast cancer. The results indicated that Abemaciclib + ET, Dalpiciclib + ET, Palbociclib + ET, and Ribociclib + ET exhibited similar therapeutic effects in terms of improving objective response rate (ORR), disease control rate (DCR) and reducing the occurrence of fatigue, all of which were superior to ET alone. However, in terms of prolonging progression-free survival (PFS) and overall survival (OS), Dalpiciclib + ET significantly improved PFS compared to Ribociclib + ET, Palbociclib + ET, Abemaciclib and Palbociclib. Ribociclib + ET significantly improved OS compared to Palbociclib + ET. Regarding overall adverse reaction events (AREs), Dalpiciclib + ET had a higher incidence compared to Ribociclib + ET. The incidence of neutropenia caused by Dalpiciclib + ET was significantly higher compared to Palbociclib + ET, Ribociclib + ET, Abemaciclib, and Palbociclib. Abemaciclib + ET demonstrated the worst safety profile concerning diarrhea.

Conclusion

Abemaciclib + ET likely represents the most effective option in terms of therapeutic effects, but it is prone to causing diarrhea and fatigue. On the other hand, Dalpiciclib + ET likely demonstrates the best efficacy in terms of PFS but exhibits the poorest safety profile, particularly in relation to neutropenia. Therefore, clinicians should exercise increased vigilance in monitoring and managing adverse effects when prescribing Abemaciclib + ET and Dalpiciclib + ET.

A bibliometric and visualization analysis of research trends and hotspots on targeted therapy for breast cancer from 2003 to 2022

Background

Breast cancer is a significant public health issue, exhibiting the most pronounced occurrence and fatality rates among malignant neoplasms globally. Targeted therapy is a medical intervention that focuses on specific molecular markers. This study aims to investigate and evaluate the current research trends and directions in the field of targeted therapy for breast cancer using bibliometric analysis.

Method

The Web of Science database was utilized to retrieve relevant articles published between 2003 and 2022. The VOSviewer software and Bibliometrix package in the R language were employed to conduct co-occurrence and clustering analyses of authors, countries, institutions, journals, references, and the CiteSpace tool was utilized for keyword burst detection.

Results

A total of 2,258 articles were included and the annual number of publications increased rapidly. The most prolific country on this topic was the USA (n=898, 39.77%) and the University of Texas MD Anderson Cancer Center published most papers (n=93). Dennis J. Slamon and Gabriel N. Hortobagyi stood out in the field, with Dennis J. Slamon leading in terms of co-citations(n=653) and Gabriel N. Hortobagyi topping the list in terms of published articles(n=18). The most productive journal was Breast Cancer Research and Treatment and the most cited journal was Journal of Clinical Oncology. The clustering of keywords indicated that the primary focus of researches in the past two decades was on the development and clinical evaluation of tumor-targeted drugs associated with the epidermal growth factor receptor (EGFR) family signaling pathway, and explored mechanisms related to biological behavior of breast cancer. Keywords co-occurrence and burst analysis identified current research hotspots and potential research trends.

Conclusion

This study employed bibliometric analysis to examine research on targeted therapy for breast cancer over a span of 20 years, and identified development trends of research and elucidated potential research trajectories in the domain of this topic. This study helps in the identification of prospective collaborators and partner institutions for researchers.

A Signal-Finding Study of Abemaciclib in Heavily Pretreated Patients with Metastatic Castration-Resistant Prostate Cancer: Results from CYCLONE 1

PURPOSE

Cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors radically changed the treatment paradigm for breast cancer. Similar to estrogen receptor in breast cancer, androgen receptor signaling activates cyclin D-CDK4/6, driving proliferation and resistance to hormonal manipulation in prostate cancer. This study was designed to detect signals of clinical activity for abemaciclib in treatment-refractory metastatic castration-resistant prostate cancer (mCRPC).

PATIENTS AND METHODS

Eligible patients had progressive mCRPC, measurable disease, and previously received ≥1 novel hormonal agent(s) and 2 lines of taxane chemotherapy. Abemaciclib 200 mg twice daily was administered on a continuous dosing schedule. Primary endpoint was objective response rate (ORR) without concurrent bone progression. This study was designed to detect a minimum ORR of 12.5%.

RESULTS

At trial entry, 40 (90.9%) of 44 patients had objective radiographic disease progression, 4 (9.1%) had prostate-specific antigen (PSA)-only progression, and 20 (46.5%) had visceral metastases (of these, 60% had liver metastases). Efficacy analyses are as follows: ORR without concurrent bone progression: 6.8%; disease control rate: 45.5%; median time to PSA progression: 6.5 months [95% confidence interval (CI), 3.2-NA]; median radiographic PFS; 2.7 months (95% CI, 1.9-3.7); and median OS, 8.4 months (95% CI, 5.6-12.7). Most frequent grade ≥3 treatment-emergent adverse events (AE) were neutropenia (25.0%), anemia, and fatigue (11.4% each). No grade 4 or 5 AEs were related to abemaciclib.

CONCLUSIONS

Abemaciclib monotherapy was well tolerated and showed clinical activity in this heavily pretreated population, nearly half with visceral metastases. This study is considered preliminary proof-of-concept and designates CDK4/6 as a valid therapeutic target in prostate cancer.

Updated Austrian treatment algorithm for metastatic triple-negative breast cancer

Approximately 15% of newly diagnosed breast cancer patients have neither hormone receptors expression nor HER2 overexpression and/or HER2/neu gene amplification. This subtype of breast cancer is known as Triple Negative Breast Cancer (TNBC), and carries a significantly elevated risk of local and distant recurrence. In comparison with other breast cancer subtypes, there is a higher rate of visceral and brain metastases. The majority of metastases of TNBC are diagnosed within three years after initial breast cancer diagnosis. While there have been major advances in hormone-receptor- positive and in human epidermal growth factor receptor 2 (HER2)-positive disease over the past two decades, only limited improvements in outcomes for patients with triple negative breast cancer (TNBC) have been observed. A group of Austrian breast cancer specialists therefore convened an expert meeting to establish a comprehensive clinical risk-benefit profile of available mTNBC therapies and discuss the role sacituzumab govitecan may play in the treatment algorithm of the triple-negative breast cancer patients.

Navigating Breast Cancer Oligometastasis and Oligoprogression: Current Landscape and Future Directions

PURPOSE

We examine the potential for curative approaches among metastatic breast cancer (MBC) patients by exploring the recent literature on local ablative therapies like surgery and stereotactic body radiation therapy (SBRT) in patients with oligometastatic (OM) breast cancer. We also cover therapies for MBC patients with oligoprogressive (OP) disease.

KEY FINDINGS

Surgery and SBRT have been studied for OM and OP breast cancer, mainly in retrospective or non-randomized trials. While many studies demonstrated favorable results, a cooperative study and single-institution trial found no support for surgery/SBRT in OM and OP cases, respectively.

CONCLUSION

While there is interest in applying local therapies to OM and OP breast cancer, the current randomized data does not back the routine use of surgery or SBRT, particularly when considering the potential for treatment-related toxicities. Future research should refine patient selection through advanced imaging and possibly explore these therapies specifically in patients with hormone receptor-positive or HER2-positive disease.

Overexpression of COL11A1 confers tamoxifen resistance in breast cancer

Breast cancer is the most commonly diagnosed malignancy and benefits from endocrine agents such as tamoxifen. However, the development of drug resistance in cancerous cells often leads to recurrence, thus limiting the therapeutic benefit. Identification of potential biomarkers that can predict response to tamoxifen and recognize patients who will clinically benefit from this therapy is urgently needed. In this study, we report that high collagen type XI alpha 1 (COL11A1) expression was associated with poor therapeutic response and prognosis in breast cancer patients treated with tamoxifen. To confirm the role of COL11A1 in the development of tamoxifen resistance, we established MCF-7/COL11A1 and T47D/COL11A1 cell lines, which stably expressed COL11A1. Compared with parental MCF-7 and T47D, MCF-7/COL11A1 and T47D/COL11A1 cells were more resistant to 4-OHT-induced growth inhibition. Moreover, the level of COL11A1 expression was upregulated in tamoxifen-resistant MCF-7/TamR and T47D/TamR cell lines, and depletion of COL11A1 markedly sensitized the cells to 4-OHT in vitro and in vivo. Interestingly, the level of estrogen receptor α (ERα) expression was elevated, probably due to the increased COL11A1 in TamR cells. In addition, knockdown of COL11A1 decreased the expression of ERα and its downstream target genes. Overall, our findings suggest that overexpressed COL11A1 contributes to tamoxifen resistance, and targeting COL11A1 holds great promise for reversing endocrine resistance.

The therapeutic effect of traditional Chinese medicine on breast cancer through modulation of the Wnt/β-catenin signaling pathway

Breast cancer, the most prevalent malignant tumor among women globally, is significantly influenced by the Wnt/β-catenin signaling pathway, which plays a crucial role in its initiation and progression. While conventional chemotherapy, the standard clinical treatment, suffers from significant drawbacks like severe side effects, high toxicity, and limited prognostic efficacy, Traditional Chinese Medicine (TCM) provides a promising alternative. TCM employs a multi-targeted therapeutic approach, which results in fewer side effects and offers a high potential for effective treatment. This paper presents a detailed analysis of the therapeutic impacts of TCM on various subtypes of breast cancer, focusing on its interaction with the Wnt/β-catenin signaling pathway. Additionally, it explores the effectiveness of both monomeric and compound forms of TCM in the management of breast cancer. We also discuss the potential of establishing biomarkers for breast cancer treatment based on key proteins within the Wnt/β-catenin signaling pathway. Our aim is to offer new insights into the prevention and treatment of breast cancer and to contribute to the standardization of TCM.

Attrition in the First Three Therapy Lines in Patients with Advanced Breast Cancer in the German Real-World PRAEGNANT Registry

Background With more effective therapies for patients with advanced breast cancer (aBC), therapy sequences are becoming increasingly important. However, some patients might drop out of the treatment sequence due to deterioration of their life status. Since little is known about attrition in the real-world setting, this study assessed attrition in the first three therapy lines using a real-world registry. Methods Patients with information available on the first three therapy lines were selected from the German PRAEGNANT registry (NCT02338167). Attrition was determined for each therapy line using competing risk analyses, with the start of the next therapy line or death as endpoints. Additionally, a simple attrition rate was calculated based on the proportion of patients who completed therapy but did not start the next therapy line. Results Competitive risk analyses were performed on 3988 1st line, 2651 2nd line and 1866 3rd line patients. The probabilities of not starting the next therapy line within 5 years after initiation of 1st, 2nd and 3rd line therapy were 30%, 24% and 24% respectively. Patients with HER2-positive disease had the highest risk for attrition, while patients with HRpos/HER2neg disease had the lowest risk. Attrition rates remained similar across molecular subgroups in the different therapy lines. Conclusion Attrition affects a large proportion of patients with aBC, which should be considered when planning novel therapy concepts that specifically address the sequencing of therapies. Taking attrition into account could help understand treatment effects resulting from sequential therapies and might help develop treatment strategies that specifically aim at maintaining quality of life.

Abemaciclib plus endocrine therapy versus chemotherapy after progression on prior palbociclib in HR+/HER2- metastatic breast cancer: A single center real-world study in China

BACKGROUND

Cyclin-dependent kinase (CDK) 4/6 inhibitor plus endocrine therapy (ET) become standard-of-care for patients with hormone receptor-positive, human epidermal growth factor receptor-2 negative (HR+/HER2-) metastatic breast cancer (MBC). However, the optimal therapeutic paradigm after progression on CDK4/6 inhibitor remains unclear. This study aimed to evaluate the efficacy and safety of abemaciclib with switching ET versus chemotherapy after progression on prior palbociclib-based ET in Chinese patients with HR+/HER2- MBC.

METHODS

From 414 consecutive patients with HR+/HER2- MBC who had been treated with palbociclib plus ET from September 2018 to May 2022 in Peking University Cancer Hospital, we identified 80 patients who received abemaciclib plus switching ET or chemotherapy after progression on palbociclib, matched for age, original stage at diagnosis, disease-free interval, and tumor burden at 1:1 ratio. The primary endpoint was progression-free survival (PFS) compared using the Kaplan-Meier method. A Cox proportional hazard model was performed to identify clinical factors associated with PFS in the abemaciclib group.

RESULTS

The median PFS was 6.0 months (95% confidence interval [CI]: 3.94-8.06) in abemaciclib group and 4.0 months (95% CI, 2.52-5.49) in chemotherapy group (p = 0.667). And, there was no difference in median PFS between the sequential and nonsequential arm (6.0 vs. 6.0 months) in the abemaciclib group though fewer lines of prior systemic therapy and longer PFS from prior palbociclib in the sequential arm. However, patients with prior palbociclib as the first-line therapy had a significantly longer median PFS versus prior palbociclib as ≥2nd-line therapy (11.0 vs. 5.0 months, p = 0.043). Based on multivariable analysis, ER+/PR+ was an independent factor associated with longer PFS. There was no significant difference in overall survival between the abemaciclib and chemotherapy groups (p = 0.069).

CONCLUSION

Our findings indicate that abemaciclib plus switching ET might be one of feasible treatment options for Chinese patients with HR+/HER2- MBC after progression on prior palbociclib-based therapy in addition to chemotherapy.

CDK4/6 Inhibition - Therapy Sequences and the Quest to Find the Best Biomarkers - an Overview of Current Programs

In recent years, new targeted therapies have been developed to treat patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer. Some of these therapies have not just become the new therapy standard but also led to significantly longer overall survival rates. The cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i) have become the therapeutic standard for first-line therapy. Around 70 - 80% of patients are treated with a CDK4/6i. In recent years, a number of biomarkers associated with progression, clonal selection or evolution have been reported for CDK4/6i and their endocrine combination partners. Understanding the mechanisms behind treatment efficacy and resistance is important. A better understanding could contribute to planning the most effective therapeutic sequences and utilizing basic molecular information to overcome endocrine resistance. One study with large numbers of patients which aims to elucidate these mechanisms is the Comprehensive Analysis of sPatial, TempORal and molecular patterns of ribociclib efficacy and resistance in advanced Breast Cancer patients (CAPTOR BC) trial. This overview summarizes the latest clinical research on resistance to endocrine therapies, focusing on CDK4/6 inhibitors and discussing current study concepts.

From standard therapies to monoclonal antibodies and immune checkpoint inhibitors - an update for reconstructive surgeons on common oncological cases

Malignancies represent a persisting worldwide health burden. Tumor treatment is commonly based on surgical and/or non-surgical therapies. In the recent decade, novel non-surgical treatment strategies involving monoclonal antibodies (mAB) and immune checkpoint inhibitors (ICI) have been successfully incorporated into standard treatment algorithms. Such emerging therapy concepts have demonstrated improved complete remission rates and prolonged progression-free survival compared to conventional chemotherapies. However, the in-toto surgical tumor resection followed by reconstructive surgery oftentimes remains the only curative therapy. Breast cancer (BC), skin cancer (SC), head and neck cancer (HNC), and sarcoma amongst other cancer entities commonly require reconstructive surgery to restore form, aesthetics, and functionality. Understanding the basic principles, strengths, and limitations of mAB and ICI as (neo-) adjuvant therapies and treatment alternatives for resectable or unresectable tumors is paramount for optimized surgical therapy planning. Yet, there is a scarcity of studies that condense the current body of literature on mAB and ICI for BC, SC, HNC, and sarcoma. This knowledge gap may result in suboptimal treatment planning, ultimately impairing patient outcomes. Herein, we aim to summarize the current translational endeavors focusing on mAB and ICI. This line of research may serve as an evidence-based fundament to guide targeted therapy and optimize interdisciplinary anti-cancer strategies.

Therapeutic Strategies for RB1-Deficient Cancers: Intersecting Gene Regulation and Targeted Therapy

The retinoblastoma (RB) transcriptional corepressor 1 (RB1) is a critical tumor suppressor gene, governing diverse cellular processes implicated in cancer biology. Dysregulation or deletion in RB1 contributes to the development and progression of various cancers, making it a prime target for therapeutic intervention. RB1's canonical function in cell cycle control and DNA repair mechanisms underscores its significance in restraining aberrant cell growth and maintaining genomic stability. Understanding the complex interplay between RB1 and cellular pathways is beneficial to fully elucidate its tumor-suppressive role across different cancer types and for therapeutic development. As a result, investigating vulnerabilities arising from RB1 deletion-associated mechanisms offers promising avenues for targeted therapy. Recently, several findings highlighted multiple methods as a promising strategy for combating tumor growth driven by RB1 loss, offering potential clinical benefits in various cancer types. This review summarizes the multifaceted role of RB1 in cancer biology and its implications for targeted therapy.

CDK Inhibitors and FDA: Approved and Orphan

The protein kinases are a large family of enzymes which catalyze protein phosphorylation at certain amino acids [...].

Real-world study of palbociclib combined with endocrine therapy for patients with metastatic breast cancer: A comparison of subsequent treatment patterns and HER2 expression analysis

BACKGROUND

Cyclin-dependent kinase 4/6 inhibitors combined with endocrine therapy (ET) comprise the standard treatment for patients with hormone receptor-positive and human epidermal growth factor 2 (HER2)-negative metastatic breast cancer. The optimal systematic treatment after progression on palbociclib and the role of HER2 expression among these patients remain unclear.

METHODS

The authors retrospectively identified 361 patients who received palbociclib combined with ET. Progression-free survival (PFS) and overall survival (OS) were analyzed based on subsequent treatments and HER2 status (PFSsub and OSsub, respectively). PFS1 and OS1 were calculated from palbociclib administration to disease progression/death and death from any cause, respectively. PFSsub and OSsub were calculated from subsequent treatment initiation.

RESULTS

The median PFS1 and OS1 were 10.2 and 39.9 months, respectively. The median PFSsub and OSsub of 111 patients (54.7%) who received chemotherapy were 4.9 months and 20.0 months, respectively, whereas those of 89 patients (43.8%) who received endocrine backbone therapy were 5.9 months and 29.3 months, respectively. Among them, 31 patients (15.3%) who received abemaciclib combined with new ET showed better PFSsub and OSsub (12.2 months and not reached, respectively). The median PFS1 was significantly shorter in the HER2-low subgroup than in the HER2-zero subgroup among patients who received second-line or later palbociclib (6.1 vs. 7.8 months; p = .040) but did not differ among patients who received first-line palbociclib.

CONCLUSIONS

Various regimens after palbociclib use were received. An improvement was noted in PFS among patients who received endocrine backbone therapy relative to chemotherapy, which may have been secondary to the receipt of chemotherapy by patients with more aggressive disease. HER2 status was not related to the effect of first-line palbociclib, but it may play a role in later lines.

Real-World Evidence of Ribociclib Plus Aromatase Inhibitors as First-Line Treatment in Advanced Breast Cancer: The BrasiLEEira Study

PURPOSE

Cyclin inhibitors plus endocrine therapy represent the reference standard for hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) locally advanced or metastatic breast cancer (ABC). Efficacy results on hard end points such as overall survival come from well-designed randomized clinical trials (RCTs). However, a limitation of RCTs is the low external results validity, and their extrapolation to a broader population may not be appropriate. Real-world studies can overcome these limitations, also increasing the reliability of RCTs.

MATERIALS AND METHODS

The BrasiLEEira was an observational, longitudinal, retrospective, multicenter study to evaluate the effectiveness and safety of ribociclib plus nonsteroidal aromatase inhibitors in Brazilian women age 18 years or older with HR+/HER2- ABC. The study was approved by the institutional review boards of all 11 hospitals. Data were collected anonymously from medical records using an electronic case report form designed by an independent academic research organization, which conducted the study considering all recommendations of international guidelines. The primary end point was 1-year progression-free survival (PFS) rate. Secondary end points included mortality, dose reduction, and safety.

RESULTS

The mean age of 76 patients was 57 years, and 28.9% were Black/Brown. The most prevalent comorbidity was arterial hypertension (34.7%). About 26.0% had endocrine-resistant disease, and 54.1% had more than three metastatic sites. The PFS rate was 77.6%. Three patients died (3.9%). Dose reductions occurred in 37.7% of patients. The most common adverse event was neutropenia (68.4%).

CONCLUSION

The high-quality evidence from the BrasiLEEira study corroborates the RCTs' findings, expanding its validity to a broader spectrum and underrepresented population who may benefit from ribociclib treatment.

Predicting drug-drug interactions in breast cancer patients treated with CDK4/6 inhibitors and forward planning

INTRODUCTION

Cyclin-dependent kinase (CDK) 4/6 inhibitors are cornerstones in the treatment of Hormone Receptor (HR) positive and Human Epidermal Growth factor (HER2) negative metastatic breast cancer. Given their widespread use in the metastatic setting and emerging use in the adjuvant setting, studying drug-drug interactions (DDI) of these medications is of utmost importance.

AREAS COVERED

This review provides key background information on the CDK4/6 inhibitors, palbociclib, ribociclib, and abemaciclib. We discuss drug-drug interactions including those with proton pump inhibitors as well as CYP3A substrates, inhibitors, and inducers. We describe the effect of these drugs on membrane transporters and their substrates as well as those drugs that increase risk of CDK4/6 toxicities. Finally, we explore future directions for strategies to minimize drug-drug interactions.

EXPERT OPINION

It is crucial to be mindful of medications that may interfere with drug absorption, such as proton pump inhibitors, as well as those that interfere with drug metabolism, such as CYP3A4 inhibitors and inducers. Additionally, special consideration should be given to populations at higher risk for polypharmacy, such as older patients with greater comorbidities. These interactions and patient characteristics should be considered when developing individual treatment plans with CDK4/6 inhibitors.

Ribociclib plus Endocrine Therapy in Early Breast Cancer

BACKGROUND

Ribociclib has been shown to have a significant overall survival benefit in patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Whether this benefit in advanced breast cancer extends to early breast cancer is unclear.

METHODS

In this international, open-label, randomized, phase 3 trial, we randomly assigned patients with HR-positive, HER2-negative early breast cancer in a 1:1 ratio to receive ribociclib (at a dose of 400 mg per day for 3 weeks, followed by 1 week off, for 3 years) plus a nonsteroidal aromatase inhibitor (NSAI; letrozole at a dose of 2.5 mg per day or anastrozole at a dose of 1 mg per day for ≥5 years) or an NSAI alone. Premenopausal women and men also received goserelin every 28 days. Eligible patients had anatomical stage II or III breast cancer. Here we report the results of a prespecified interim analysis of invasive disease-free survival, the primary end point; other efficacy and safety results are also reported. Invasive disease-free survival was evaluated with the use of the Kaplan-Meier method. The statistical comparison was made with the use of a stratified log-rank test, with a protocol-specified stopping boundary of a one-sided P-value threshold of 0.0128 for superior efficacy.

RESULTS

As of the data-cutoff date for this prespecified interim analysis (January 11, 2023), a total of 426 patients had had invasive disease, recurrence, or death. A significant invasive disease-free survival benefit was seen with ribociclib plus an NSAI as compared with an NSAI alone. At 3 years, invasive disease-free survival was 90.4% with ribociclib plus an NSAI and 87.1% with an NSAI alone (hazard ratio for invasive disease, recurrence, or death, 0.75; 95% confidence interval, 0.62 to 0.91; P = 0.003). Secondary end points - distant disease-free survival and recurrence-free survival - also favored ribociclib plus an NSAI. The 3-year regimen of ribociclib at a 400-mg starting dose plus an NSAI was not associated with any new safety signals.

CONCLUSIONS

Ribociclib plus an NSAI significantly improved invasive disease-free survival among patients with HR-positive, HER2-negative stage II or III early breast cancer. (Funded by Novartis; NATALEE ClinicalTrials.gov number, NCT03701334.).

Efficacy of first-line CDK 4-6 inhibitors in premenopausal patients with metastatic breast cancer and the effect of dose reduction due to treatment-related neutropenia on efficacy: a Turkish Oncology Group (TOG) study

The only phase 3 study on the effectiveness of CDK 4-6 inhibitors in first-line treatment in premenopausal patients with hormone receptor (HR) positive, HER2 negative metastatic breast cancer is the MONALEESA-7 study, and data on the effectiveness of palbociclib is limited. Data are also limited regarding the effectiveness of CDK 4-6 inhibitors in patients whose dose was reduced due to neutropenia, the most common side effect of CDK 4-6 inhibitors. In our study, we aimed to evaluate the effectiveness of palbociclib and ribociclib in first-line treatment in patients with premenopausal metastatic breast cancer and the effect of dose reduction due to neutropenia on progression-free survival. Our study is a multicenter, retrospective study, and factors affecting progression-free survival (PFS) were examined in patients diagnosed with metastatic premenopausal breast cancer from 29 different centers and receiving combination therapy containing palbociclib or ribociclib in the metastatic stage. 319 patients were included in the study. The mPFS for patients treated with palbociclib was 26.83 months, and for those receiving ribociclib, the mPFS was 29.86 months (p = 0.924). mPFS was 32.00 months in patients who received a reduced dose, and mPFS was 25.96 months in patients who could take the initial dose, and there was no statistical difference (p = 0.238). Liver metastasis, using a fulvestrant together with a CDK 4-6 inhibitor, ECOG PS 1 was found to be a negative prognostic factor. No new adverse events were observed. In our study, we found PFS over 27 months in patients diagnosed with premenopausal breast cancer with CDK 4-6 inhibitors used in first-line treatment, similar to post-menopausal patients. We did not detect any difference between the effectiveness of the two CDK 4-6 inhibitors, and we showed that there was no decrease in the effectiveness of the CDK 4-6 inhibitor in patients whose dose was reduced due to neutropenia.

PRMT5 is an actionable therapeutic target in CDK4/6 inhibitor-resistant ER+/RB-deficient breast cancer

CDK4/6 inhibitors (CDK4/6i) have improved survival of patients with estrogen receptor-positive (ER+) breast cancer. However, patients treated with CDK4/6i eventually develop drug resistance and progress. RB1 loss-of-function alterations confer resistance to CDK4/6i, but the optimal therapy for these patients is unclear. Through a genome-wide CRISPR screen, we identify protein arginine methyltransferase 5 (PRMT5) as a molecular vulnerability in ER+/RB1-knockout breast cancer cells. Inhibition of PRMT5 blocks the G1-to-S transition in the cell cycle independent of RB, leading to growth arrest in RB1-knockout cells. Proteomics analysis uncovers fused in sarcoma (FUS) as a downstream effector of PRMT5. Inhibition of PRMT5 results in dissociation of FUS from RNA polymerase II, leading to hyperphosphorylation of serine 2 in RNA polymerase II, intron retention, and subsequent downregulation of proteins involved in DNA synthesis. Furthermore, treatment with the PRMT5 inhibitor pemrametostat and a selective ER degrader fulvestrant synergistically inhibits growth of ER+/RB-deficient cell-derived and patient-derived xenografts. These findings highlight dual ER and PRMT5 blockade as a potential therapeutic strategy to overcome resistance to CDK4/6i in ER+/RB-deficient breast cancer.

Case report: Cutaneous metastases as a first manifestation from breast cancer with concurrent gastric metastases

Background: Breast cancer represents a leading cause of malignancy among Chinese women, posing a significant health burden. The diagnosis of metastatic breast cancer, particularly to uncommon sites like the skin and stomach, presents distinct challenges. Case introduction: This case report describes a 71-year-old Chinese women with a persistent back rash lasting more than 6 months. Physical examination revealed red papules on her back. Immunohistochemistry confirmed positive for cytokeratin 7(CK7), GATA-3 and GCDFP15, as well as negative staining of cytokeratin 20 (CK20), suggesting breast cancer metastasis. Further evaluation revealed a breast nodule and axillary lymph node enlargement, with biopsies confirming invasive lobular carcinoma (ILC). Abdominal computed tomography (CT) revealed thickening of the gastric and ascending colon walls. Gastroscopy revealed chronic superficial atrophic gastritis. However, gastric metastasis was further confirmed by pathology. The patient initiated endocrine therapy with fulvestrant and exemestane, resulting in rash resolution and stable breast and stomach lesions after 3 months. Overall, the patient is experiencing an improvement in her condition and remains stable while continuing treatment. Conclusion: This case highlights the importance of considering atypical metastatic patterns in breast cancer and the potential efficacy of endocrine therapies in managing such cases. Moreover, it emphasizes the need for vigilance in breast cancer patients, especially those with ILC, as gastrointestinal symptoms may indicate gastric metastasis (GMs). Ultimately, early detection and appropriate treatment strategies, such as endocrine therapy, can contribute to improved outcomes in these challenging cases.

First-line CDK4/6 inhibitor-based combinations for HR+/HER2- advanced breast cancer: A Bayesian network meta-analysis

BACKGROUND

International guidelines recommend cyclin-dependent kinase 4/6 inhibitor (CDK4/6i)-based first-line therapy for hormone receptor-positive, human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC). However, direct drug comparisons are lacking. We aimed to identify the most effective and safe therapy through network meta-analysis (NMA).

METHODS

We searched PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and OpenGrey up to September 30, 2023. Eligible studies included randomized controlled trials (RCTs) assessing endocrine therapy alone or in combination with CDK4/6i as first-line endocrine treatment for HR+/HER2- ABC patients. The hazard ratios for progression-free survival (PFS) and overall survival (OS) and relative risks for objective response rate and adverse events (AEs) were available in selected trials. We performed a Bayesian NMA following PRISMA guidelines.

RESULTS

Thirteen RCTs, involving 10 treatments, were included. Most studies were at low risk of bias. Regarding PFS, ribociclib+fulvestrant ranked first with a surface under the cumulative ranking curve (SUCRA) of 85.0%, followed by dalpiciclib+nonsteroidal aromatase inhibitor (NSAI) (SUCRA = 78.9%). Considering OS, the top three ranked treatments were ribociclib+fulvestrant (SUCRA = 94.1%), abemaciclib+NSAI (SUCRA = 69.9%), and ribociclib+NSAI (SUCRA = 68.5%). Out of four CDK4/6is, ribociclib minimized the grade 3/4 AEs, while dalpiciclib demonstrated the worst safety. Publication bias could not be ignored in our analyses, and the certainty of evidence was downgraded primarily due to imprecision.

CONCLUSIONS

Ribociclib+fulvestrant probably represents the best option in a first-line setting. When combined with NSAI, dalpiciclib likely showed the best efficacy but the worst safety. Abemaciclib+NSAI and ribociclib+NSAI could also be promising treatments, while palbociclib presented inferiority. (PROSPERO Registration No. CRD42022370271).

TROPION-Breast01: Datopotamab deruxtecan vs chemotherapy in pre-treated inoperable or metastatic HR+/HER2- breast cancer

Improving the prognosis for patients with metastatic HR+/HER2- breast cancer remains an unmet need. Patients with tumors that have progressed on endocrine therapy and/or are not eligible for endocrine therapy had limited treatment options beyond chemotherapy. Antibody-drug conjugates are a novel and promising treatment class in this setting. Datopotamab deruxtecan (Dato-DXd) consists of a TROP2-directed humanized IgG1 monoclonal antibody attached via a serum-stable cleavable linker to a topoisomerase I inhibitor payload. TROPION-Breast01 is an ongoing phase III study that is evaluating the efficacy and safety of Dato-DXd compared with investigator's choice of standard-of-care chemotherapy in patients with inoperable or metastatic HR+/HER2- breast cancer who have received one or two prior lines of systemic chemotherapy in the inoperable or metastatic setting. Clinical Trial Registration: NCT05104866 (ClinicalTrials.gov).

INX-315, a Selective CDK2 Inhibitor, Induces Cell Cycle Arrest and Senescence in Solid Tumors

Cyclin-dependent kinase 2 (CDK2) is thought to play an important role in driving proliferation of certain cancers, including those harboring CCNE1 amplification and breast cancers that have acquired resistance to CDK4/6 inhibitors (CDK4/6i). The precise impact of pharmacologic inhibition of CDK2 is not known due to the lack of selective CDK2 inhibitors. Here we describe INX-315, a novel and potent CDK2 inhibitor with high selectivity over other CDK family members. Using cell-based assays, patient-derived xenografts (PDX), and transgenic mouse models, we show that INX-315 (i) promotes retinoblastoma protein hypophosphorylation and therapy-induced senescence (TIS) in CCNE1-amplified tumors, leading to durable control of tumor growth; (ii) overcomes breast cancer resistance to CDK4/6i, restoring cell cycle control while reinstating the chromatin architecture of CDK4/6i-induced TIS; and (iii) delays the onset of CDK4/6i resistance in breast cancer by driving deeper suppression of E2F targets. Our results support the clinical development of selective CDK2 inhibitors.

SIGNIFICANCE

INX-315 is a novel, selective inhibitor of CDK2. Our preclinical studies demonstrate activity for INX-315 in both CCNE1-amplified cancers and CDK4/6i-resistant breast cancer. In each case, CDK2 inhibition induces cell cycle arrest and a phenotype resembling cellular senescence. Our data support the development of selective CDK2 inhibitors in clinical trials. See related commentary by Watts and Spencer, p. 386. This article is featured in Selected Articles from This Issue, p. 384.

Recent progress of CDK4/6 inhibitors' current practice in breast cancer

Dysregulated cellular proliferation represents a hallmark feature across all cancers. Aberrant activation of the cyclin-dependent kinase 4 and 6 (CDK4/6) pathway, independent of mitogenic signaling, engenders uncontrolled breast cancer cell proliferation. Consequently, the advent of CDK4/6 inhibition has constituted a pivotal milestone in the realm of targeted breast cancer therapy. The combination of CDK4/6 inhibitors (CDK4/6i) with endocrine therapy (ET) has emerged as the foremost therapeutic modality for patients afflicted with hormone receptor-positive (HR + )/HER2-negative (HER2-) advanced breast cancer. At present, the Food and Drug Administration (FDA) has sanctioned various CDK4/6i for employment as the primary treatment regimen in HR + /HER2- breast cancer. This therapeutic approach has demonstrated a substantial extension of progression-free survival (PFS), often amounting to several months, when administered alongside endocrine therapy. Within this comprehensive review, we systematically evaluate the utilization strategies of CDK4/6i across various subpopulations of breast cancer and explore potential therapeutic avenues following disease progression during application of CDK4/6i therapy.

Digging in real-word electronic database for assessing CDK 4/6 inhibitors adherence in breast cancer patients from Romania

Introduction: It is imperative for patients to respect the prescribed treatments to achieve the anticipated clinical outcomes, including the outpatients receiving oral anti-cancer drugs such as selective cyclin-dependent kinase 4/6 inhibitors (CDK 4/6i). With the introduction of three CDK 4/6i drugs in the Romanian pharmaceutical market in 2018, our study aimed to evaluate medication adherence and the influencing factors among patients undergoing treatment with palbociclib, ribociclib, or abemaciclib for advanced or metastatic breast cancer. Methods: Medication adherence was assessed using the Proportion of Days Covered (PDC) method, and Spearman correlation analysis was conducted to explore the relationships between adherence, age, gender, and follow-up duration. Results: The study enrolled 330 breast cancer patients, with an average follow-up period of 14.6 ± 12.5 months for palbociclib, 10.6 ± 7.1 months for ribociclib, and 8.6 ± 6.4 months for abemaciclib-treated patients. A small proportion of patients demonstrated non-adherence: 12.8% for palbociclib, 14.6% for ribociclib, and 14.7% for abemaciclib. Among patients receiving palbociclib, there was no significant correlation between adherence, age (rho = 0.07, p = 0.35), or gender (rho = -0.144, p = 0.054). However, a significant correlation was found with the duration of follow-up (rho = -0.304, p < 0.0001). Similar results were observed for patients receiving ribociclib or abemaciclib. Most patients received combination therapy with letrozole (46%) and exemestane (13%) for palbociclib, letrozole (48%) and fulvestrant (19%) for ribociclib, and fulvestrant (39%) and letrozole (27%) for abemaciclib, Discussion: High adherence rates were observed among patients treated with CDK 4/6i drugs, with no significant differences noted among the three drugs in this class. However, the collected patient data was limited, lacking information on adverse reactions that could potentially lead to treatment discontinuation, as determined by the oncologist's decision not to prescribe. Consequently, a comprehensive understanding of all factors contributing to the low adherence levels is hindered.

Cerebral venous sinus thrombosis in a patient treated with ribociclib for metastatic breast cancer. Case reports and literature review

Breast cancer is the most diagnosed cancer among women worldwide. Cyclin dependent kinase 4/6 inhibitors (ribociclib, palbociclib, and abemaciclib) modulate endocrine resistance and are widely used treatment for patients with advanced-stage hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer. Reports of both venous and arterial thromboembolic events, as a complication of cyclin dependent kinase 4/6 inhibitors, are increasingly recognized, but none involved cerebral venous sinus. We herein report on a 44-year-old female patient who initially presented with an early-stage breast cancer treated with surgery, chemotherapy, radiation therapy and finished 5 years of tamoxifen uneventfully. Eight years after her initial diagnosis, she relapsed with a solitary brain lesion which was resected and treated with radiation therapy, and was then started on aromatase inhibitors. Few months later, she progressed with biopsy-proven cervical and mediastinal lymph node metastasis. She was then switched to fulvestrant and ribociclib; both were well-tolerated. However, few weeks later she presented with increasing headache and mild dizziness. Imaging studies showed right lateral sinus acute non-occlusive thrombosis with no parenchymal changes. Patient was anticoagulated with low molecular weight heparin and follow-up visits showed stable disease with no bleeding.

Intrinsic Subtype and Overall Survival of Patients with Advanced HR+/HER2- Breast Cancer Treated with Ribociclib and ET: Correlative Analysis of MONALEESA-2, -3, -7

PURPOSE

The MONALEESA-2, -3, -7 trials demonstrated statistically significant and clinically meaningful progression-free survival and overall survival (OS) benefits with ribociclib plus endocrine therapy (ET) versus ET alone in hormone receptor-positive, HER2-negative (HR+/HER2-) advanced breast cancer (ABC). Understanding the association of intrinsic subtypes with survival outcomes could potentially guide treatment decisions. Here, we evaluated the association of intrinsic subtypes with OS in MONALEESA-2, -3, -7.

EXPERIMENTAL DESIGN

Tumor samples from MONALEESA-2, -3, -7 underwent PAM50-based subtyping. The relationship between subtypes and OS was assessed using univariable and multivariable Cox proportional hazards models. Multivariable models were adjusted for clinical prognostic factors.

RESULTS

Overall, 990 tumors (among 2,066 patients) from ribociclib (n = 580) and placebo (n = 410) arms were profiled. Subtype distribution was luminal A, 54.5%; luminal B, 28.0%; HER2-enriched (HER2E) 14.6%; and basal-like, 2.8%; and was consistent across treatment arms. The luminal A subtype had the best OS outcomes in both arms, while basal-like had the worst. Patients with HER2E (HR, 0.60; P = 0.018), luminal B (HR, 0.69; P = 0.023), and luminal A (HR, 0.75; P = 0.021) subtypes derived OS benefit with ribociclib. Patients with basal-like subtype did not derive benefit from ribociclib (HR, 1.92; P = 0.137); however, patient numbers were small (n = 28).

CONCLUSIONS

The prognostic value of intrinsic subtypes for OS was confirmed in this pooled analysis of the MONALEESA trials (largest dataset in HR+/HER2- ABC). While basal-like subtype did not benefit, a consistent OS benefit was observed with ribociclib added to ET across luminal and HER2E subtypes.

Advanced Breast Cancer Care: The Current Situation and Global Disparities

OBJECTIVES

Advanced breast cancer (ABC) is an incurable disease. The number of people living with ABC has increased globally. Disparities in ABC care exist at both individual and system levels. ABC cases in most low- and middle-income countries (LMICs) are underreported due to a lack of national cancer registries. Harmonized guidelines for resource stratification and capacity building in LMICs are under way.

DATA SOURCES

MEDLINE, Cochrane, and Google Scholar databases were used.

CONCLUSION

To improve ABC outcomes and resolve disparities, more robust health systems or pathways need to be developed across the cancer continuum in addition to social education.

IMPLICATIONS FOR NURSING PRACTICE

So far, the ABC specialist nurse role has been variable globally, and to conquer such variability, an international online nurse education and training program is in practice.

The CDK4/6 inhibitor revolution - a game-changing era for breast cancer treatment

Cyclin-dependent kinase (CDK) 4/6 inhibition in combination with endocrine therapy is the standard-of-care treatment for patients with advanced-stage hormone receptor-positive, HER2 non-amplified (HR+HER2-) breast cancer. These agents can also be administered as adjuvant therapy to patients with higher-risk early stage disease. Nonetheless, the clinical success of these agents has created several challenges, such as how to address acquired resistance, identifying which patients are most likely to benefit from therapy prior to treatment, and understanding the optimal timing of administration and sequencing of these agents. In this Review, we describe the rationale for targeting CDK4/6 in patients with breast cancer, including a summary of updated clinical evidence and how this should inform clinical practice. We also discuss ongoing research efforts that are attempting to address the various challenges created by the widespread implementation of these agents.

Treatment patterns and clinical outcomes of chidamide combined with endocrine therapy in hormone receptor-positive, HER2-negative metastatic breast cancer: A real-world multicenter study

BACKGROUND

Chidamide is a selective histone deacetylase inhibitor approved for patients with hormone receptor (HoR)-positive and HER2-negative metastatic breast cancer (MBC). We aimed to investigate the efficacy, safety, and treatment patterns of chidamide and identify clinicopathological factors that predict the efficacy of chidamide in real-world scenarios.

METHODS

Consecutive MBC patients treated with chidamide from January 2020 to August 2021 across 11 institutions were enrolled in this multicenter, retrospective study. Eligible patients were pre- and postmenopausal women who had clinically or histologically confirmed ER-positive, HER2-negative MBC, and Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Patients with multiple primary malignancies or missing baseline characteristics were excluded. Patients received 30 mg chidamide orally twice a week, combined with aromatase inhibitors (AIs) or non-AIs. Efficacy analyses included progression-free survival (PFS), objective response rate (ORR), and clinical benefit rate (CBR). Univariate and multivariate Cox regression analyses were performed to identify the potential efficacy predictors.

RESULTS

A total of 157 patients were finally included for analysis. The median number of lines prior to chidamide was four. In the whole cohort, the median PFS was 4.2 months (95% confidence interval [CI] 3.8-4.5). The ORR was 7.5% and the CBR was 31.3%. The efficacy of chidamide was consistent in patients pretreated with CDK4/6 inhibitors and patients treated with different endocrine combinations. Multivariate analysis indicated that patients who had liver metastases (adjusted HR = 1.66, 95% CI 1.14-2.43, adjusted p = 0.008) or ≥3 prior lines of treatment (adjusted HR = 1.80, 95% CI 1.17-2.77, adjusted p = 0.008) had significantly worse PFS. The most common AEs with chidamide were thrombocytopenia, leucopenia, neutropenia, and anemia.

CONCLUSION

This study provided real-world data for the use of chidamide in patients with HoR-positive and HER2-negative MBC. Our data endorsed the use of chidamide in patients pretreated with CDK4/6 inhibitors and patients treated with different endocrine combinations.

Targeted delivery of liposomal Ribociclib to SLC7A5 transporters in breast cancer cells

This study aimed to prepare SLC7A5 transporters targeted liposomes of Ribociclib (RB) by stear(o)yl conjugation of Phe, Asp, Glu amino acids to liposomes as targeting moieties. The liposomes were optimized for their formulations. Cell analysis on two cell lines of MCF-7 and NIH-3T3 were done including; cell viability test by MTT assay, cellular uptake, and cell cycle arrest by flow cytometry. The optimal liposomes showed the particle size of 123.6 ± 1.3 nm, drug loading efficiency and release efficiency of 83.87% ± 1.33% and 60.55% ± 0.46%, respectively. The RB loaded liposomes showed no hemolysis activity. Targeted liposomes increased cytotoxicity on MCF-7 cells more significantly than NIH-3T3 cells. Cell flow cytometry indicated that targeted liposomes uptake was superior to plain (non-targted) liposomes and free drug. Free drug and RB-loaded liposomes interrupted cell cycle in G1. However, amino acid-targeted liposomes arrested cells more than the free drug at this stage. Targeted liposomes reduced cell cycle with more interruption in the G2/M phase compared to the negative control.

Current and emerging treatment approaches for hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer

In the past decade, significant progress was made in treating hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (mBC), but many clinical questions remain. Cyclin-dependent kinase 4/6 inhibitors are now widely used in combination with endocrine therapy (ET) as standard of care, having demonstrated significant progression-free survival versus ET, and also significant overall survival benefits in the metastatic setting. Inhibition of the PI3K/AKT/mTOR intracellular signaling pathway coupled with ET typically follows first-line therapies. Novel endocrine options including oral selective estrogen receptor down-regulators (SERDs) are in late phases of development, with elacestrant being the first oral SERD to be approved for ESR1-mutant mBC. However, endocrine-refractory disease is inevitable in most patients and represents an area of unmet need, with current recommended options offering poor efficacy, undesirable toxicity, and reduced quality of life. Breakthrough advances in the metastatic setting came via the development of antibody-drug conjugates, which have the advantage of delivering cytotoxic payloads to tumor cells with higher tumor selectivity. Trastuzumab deruxtecan offers a novel therapeutic option for patients with HR+/HER2-low mBC and sacituzumab govitecan is a novel therapeutic option for patients with HR+/HER2- mBC, including those with unmet treatment need in the later-line endocrine-refractory setting. Data gaps still exist regarding optimal sequencing of these novel agents; additional studies into mechanisms of resistance in the metastatic setting would provide further insights. Herein, we describe the current treatment options for HR+/HER2- mBC, including the latest practice-impacting data, and provide commentary on future directions.

Efficacy, safety, and prognosis prediction in patients treated with ribociclib in combination with letrozole: Final results of phase 3b RIBECCA study in hormone receptor positive, human epidermal growth factor receptor-2 negative, locally advanced or metastatic breast cancer

BACKGROUND

In MONALEESA-2, addition of ribociclib to letrozole resulted in significantly longer progression-free survival (PFS) in postmenopausal women with HR+HER2- advanced breast cancer (ABC). RIBociclib for the treatment of advanCed breast CAncer (RIBECCA) study investigated ribociclib plus letrozole in a patient population reflecting routine clinical practice.

PATIENTS AND METHODS

In this multicenter, open-label, single-arm, phase 3b study, patients with HR+HER2- ABC not amenable to curative therapy and ECOG performance status ≤ 2 received ribociclib plus letrozole (cohort A: postmenopausal women and men in first-line; cohort B: pre-/perimenopausal women in first-line [B1], patients pretreated for advanced disease [B2]). The primary endpoint was clinical benefit rate (CBR) by week 24; secondary endpoints included overall response rate (ORR), PFS, overall survival (OS), and safety. Association of patient and tumor characteristics with PFS was analyzed by multivariable Cox regression analysis.

RESULTS

Overall, 487 patients were evaluable for efficacy, 502 for safety. By week 24, CBR was 60.8 % (95 % CI, 56.3-65.1), ORR was 19.3 % (95 % CI, 15.9-23.1). Median PFS was 21.8 months (95 % CI, 13.9-25.3) in first-line postmenopausal patients and 11.0 months (95 % CI, 8.2-16.4) in premenopausal and pretreated patients. Median OS was not reached. Higher baseline ECOG performance status, higher histological grade, and negative progesterone receptor status showed an unfavorable effect on PFS. Most common adverse events were neutropenia (50.0 %), nausea (42.0 %), and fatigue (39.2 %).

CONCLUSION

In this broad population of patients with HR+HER2- ABC, efficacy and safety results of ribociclib plus letrozole were similar to those observed in pivotal trials.

Analysis of data from the PALOMA-3 trial confirms the efficacy of palbociclib and offers alternatives for novel assessment of clinical trials

PURPOSE

There remains a need for novel therapies for patients with metastatic breast cancer (MBC). We explore the use of a novel biomarker of survival that could potentially expedite the testing of novel therapies.

METHODS

We applied a tumor regression-growth model to radiographic measurement data from 393 women with MBC enrolled in PALOMA-3 examining efficacy of palbociclib in disease that had progressed on previous endocrine therapy. 261 and 132 women were randomized to fulvestrant plus palbociclib or placebo, respectively. We estimated rates of regression (d) and growth (g) of the sensitive and resistant fractions of tumors, respectively. We compared the median g of both arms. We examined the relationship between g and progression-free and overall survival (OS).

RESULTS

As in other tumors, g is a biomarker of OS. In PALOMA-3, we found significant differences in g among patients with tumors sensitive to endocrine therapy but not amongst resistant tumors, emulating clinical trial results. Subgroup analysis found favorable g values in visceral metastases treated with palbociclib. Palbociclib efficacy demonstrated by slower g values was evident early in the trial, twelve weeks after the first 28 patients had been enrolled.

CONCLUSION

Values of g, estimated using data collected while a patient is enrolled in a clinical trial is an excellent biomarker of OS. Our results correlate with the survival outcomes of PALOMA-3 and argue strongly for using g as a clinical trial endpoint to help inform go/no-go decisions, improve trial efficiency, and deliver novel therapies to patients sooner.

Current Management and Future Perspectives of Hormone Receptor-Positive HER2-Negative Advanced Breast Cancer

OBJECTIVES

An overview of the best therapeutic approaches for the management of hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer is provided, and emerging treatment advances are discussed. Key nursing considerations and the role of the nurse in the provision of optimal care are explored.

DATA SOURCES

Data sources include peer-reviewed articles sourced in electronic databases.

CONCLUSION

With a multitude of current and emerging treatments for the management of hormone receptor-positive, HER2-negative advanced breast cancer, patients with this subtype have improved overall survival. It is essential that specialist nurses holistically support patients; this will ensure treatment adherence, leading to enhanced longevity and quality of life.

IMPLICATIONS FOR NURSING PRACTICE

Nurses play an important role in patient education and the early identification and management of treatment toxicities. Nurses also need to monitor and facilitate adherence by identifying barriers and implementing strategies to overcome them, ultimately improving patient outcomes.

Use of Pharmacokinetic and Pharmacodynamic Data to Develop the CDK4/6 Inhibitor Ribociclib for Patients with Advanced Breast Cancer

Ribociclib is an orally bioavailable, selective cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor. CDK4/6 inhibition by ribociclib leads to retinoblastoma tumor suppressor protein (Rb) reactivation, thereby restoring Rb-mediated cell cycle arrest. Ribociclib is approved for the treatment of patients with hormone receptor-positive/human epidermal growth factor receptor-2-negative (HR+/HER2-) advanced breast cancer (ABC), at the dose of 600 mg once daily (QD) during cycles of 21 days on/7 days off, with optional dose reduction to 400 mg and 200 mg. Ribociclib is rapidly absorbed with a median time to reach maximum plasma concentration of 2.4 h, mean half-life of 32.0 h and oral bioavailability of 65.8% at 600 mg. It is eliminated mainly by hepatic metabolism (~ 84% of total elimination), mostly by cytochrome P450 (CYP) 3A4. Age, body weight, race, baseline Eastern Cooperative Oncology Group status, food, mild hepatic impairment, mild-to-moderate renal impairment, proton pump inhibitors, and combination partners (non-steroidal aromatase inhibitors or fulvestrant) have no clinically relevant impact on ribociclib exposure. Ribociclib inhibits CYP3A at 600 mg leading to increased exposure of CYP3A substrates. Strong CYP3A inhibitors or inducers increase or decrease, respectively, ribociclib exposure. Exposure-safety and exposure-efficacy analyses support the clinical benefit of the 600 mg QD starting dose, with potential individualized dose reductions to 400 mg and 200 mg for effective management of the adverse events neutropenia and QTcF interval prolongation, while maintaining efficacy, in patients with HR+/HER2- ABC. Overall, these clinical pharmacology data informed ribociclib dose justification and clinical development, as well as its prescribing information for clinical use in advanced breast cancer patients.