OUP accepted manuscript

Using prognostic signatures and machine learning to identify core features associated with response to CDK4/6 inhibitor-based therapy in metastatic breast cancer

CDK4/6 inhibitors in combination with endocrine therapy are widely used to treat HR+/HER2- metastatic breast cancer leading to improved progression-free survival (PFS) compared to single agent endocrine therapy. Over 300 patients receiving standard-of-care CDK4/6 inhibitor combination therapy for metastatic disease were enrolled at a single institution. Clinical, pathological, and gene expression data were employed to define determinants for PFS duration. Visceral disease (HR 1.55, p = 0.0013), prior endocrine therapy (HR 2.34, p < 0.001), and the type of endocrine therapy (HR 2.16, p < 0.001) were highly associated with PFS duration. Multiple pre-defined gene expression signatures were employed to determine association with response to CDK4/6 inhibitor-based therapy. Random survival forest was applied to define key gene expression and clinical features associated with PFS and develop a predictive model. The time to progression predicted by this model was related to the median PFS observed in PALOMA-2/3 and PEARL studies. Interrogating genes identified as highly significant across all studies indicated common enrichment of gene networks associated with cell cycle and estrogen receptor signaling. These findings indicate that there are common features from real-world use of CDK4/6 inhibitors that could be used to infer time to progression and better inform treatment.

An Overview of Invasive Ductal Carcinoma (IDC) in Women's Breast Cancer

Invasive ductal carcinoma (IDC) is the most common type of breast cancer, primarily affecting women in the United States and across the world. This review summarizes key concepts related to IDC causes, treatment approaches, and the identification of biological markers for specific prognoses. Furthermore, we reviewed many studies, including those involving patients with IDC and ductal carcinoma in situ (DCIS) that progressed to IDC. We reported various studies on the causes of IDC, including mutations on BRCA1 and BRCA2, different levels of expression of specific genes in signaling pathways, menopause status, alcohol consumption, aging, and hormone imbalances that cause IDC while p-SMAD4 expressions, DNA methylation, regulations of hub genes, and underestimation of IDC affecting prognoses. Prompt IDC diagnosis and early intervention have been reported to demonstrate a greater probability of eradicating IDC and preventing further recurrence in the future. It is crucial for physicians and researchers to equip patients with the best information possible to proactively manage their health, whether it be for IDC prevention or treatment. Overall, our review provided a comprehensive understanding of IDC that enables patients to grasp the nature of the disease with the hope of mitigating IDC risk, decrease the anxiety of a cancer diagnosis, and encourage patients to become more involved in making informed decisions for their healthcare.

Efficacy and Safety of Cyclin-Dependent Kinase 4/6 Inhibitors in Patients with Breast Cancer: A Systematic Review and Meta-analysis of Randomized Controlled Trials and Real-World Studies

BACKGROUND

The efficacy and safety of cyclin-dependent kinase (CDK)4/6 inhibitors in patients with breast cancer have been investigated by large-scale trials sponsored by drug companies. A lack of real-world evidence may lead to biases.

OBJECTIVE

We systematically reviewed the large-scale clinical trials and real-world data to investigate the efficacy and safety of CDK4/6 inhibitors in patients with breast cancer.

PATIENTS AND METHODS

We searched PubMed, Embase, and Cochrane Library from the inception of each database to January 2024. We included both prospective and retrospective studies reporting the survival outcomes or adverse effects of CDK4/6 inhibitors in patients with breast cancer.

RESULTS

We included 41 prospective trials and 80 retrospective studies involving a total of 69,535 patients. Our meta-analysis of double-arm studies revealed that all types of CDK4/6 inhibitors significantly improved overall survival and progression-free survival. The pooled estimates of the 1-year overall survival (OS) rates and 1-year progression-free survival (PFS) rates in single-arm real-world studies were 74.8% and 49.4% for abemaciclib, 84.1% and 55.7% for palbociclib, and 93.4% and 62.2% for ribobiclib, respectively. In terms of adverse effects, Asian patients were significantly more likely to experience neutropenia and increased alanine aminotransferase, whereas Western patients were significantly more likely to have grade 3 or 4 adverse effects and constipation.

CONCLUSIONS

CDK4/6 inhibitors can improve OS and PFS in patients with advanced breast cancer. The incidence of adverse effects may differ with drugs and with ethnicity. On the basis of our findings, clinicians can select suitable CDK4/6 inhibitors for patients by conducting thorough clinical evaluations.

Timing of Dose Reductions and Survival Outcomes in Metastatic Breast Cancer Patients Treated with Cyclin-Dependent Kinase 4/6 Inhibitors

BACKGROUND/OBJECTIVES

Dose reductions in CDK4/6 inhibitors, such as ribociclib and palbociclib, are often necessary due to treatment-related toxicities in patients with advanced breast cancer. This study aims to evaluate the impact of the timing of dose reductions on progression-free survival (PFS) and overall survival (OS) in a real-world cohort.

METHODS

This single-center, retrospective study included patients treated with ribociclib or palbociclib between 2019 and 2023 at a cancer center in Turkey. Dose reductions due to drug-related toxicities were recorded, and survival outcomes were analyzed. Patients were categorized based on the timing of dose reductions: within the first 3 months (early) and after 3 months (late).

RESULTS

Among 392 patients (mean age 57.13 years), 16.8% had dose reductions within 3 months, 21.7% had late dose reductions, and 61.5% had no dose reductions. The mPFS was 14.26 months for early dose reductions, 33.12 months for late dose reductions, and 20.6 months for no dose reductions (p < 0.001). The mOS was 37.12 months for early dose reductions, not reached for late dose reductions, and 57.76 months for no dose reductions (p < 0.001). Hematological toxicity, primarily neutropenia, was the most common cause of dose reductions. The ECOG performance status, line of therapy, and CDK4/6 inhibitor type were also significant predictors of PFS and OS.

CONCLUSIONS

Early dose reductions in CDK4/6 inhibitors negatively affect PFS and OS, highlighting the importance of maintaining treatment intensity in the first 3 months. However, late dose reductions do not negatively affect progression-free survival (PFS) or overall survival (OS), with late dose reductions associated with better outcomes. Prospective studies in larger patient populations will further clarify our knowledge on this subject.

The role of Aurora kinase A in hepatocellular carcinoma: Unveiling the intriguing functions of a key but still underexplored factor in liver cancer

Aurora Kinase A (AURKA) plays a central role as a serine/threonine kinase in regulating cell cycle progression and mitotic functions. Over the years, extensive research has revealed the multifaceted roles of AURKA in cancer development and progression. AURKA's dysregulation is frequently observed in various human cancers, including hepatocellular carcinoma (HCC). Its overexpression in HCC has been associated with aggressive phenotypes and poor clinical outcomes. This review comprehensively explores the molecular mechanisms underlying AURKA expression in HCC and its functional implications in cell migration, invasion, epithelial-to-mesenchymal transition, metastasis, stemness, and drug resistance. This work focuses on the clinical significance of AURKA as a diagnostic and prognostic biomarker for HCC. High levels of AURKA expression have been correlated with shorter overall and disease-free survival in various cohorts, highlighting its potential utility as a sensitive prognostic indicator. Recent insights into AURKA's role in modulating the tumour microenvironment, particularly immune cell recruitment, may provide valuable information for personalized treatment strategies. AURKA's critical involvement in modulating cellular pathways and its overexpression in cancer makes it an attractive target for anticancer therapies. This review discusses the evidence about novel and selective AURKA inhibitors for more effective treatments for HCC.

The Effect of C-Reactive Protein/Lymphocyte Ratio (CLR) on PFS in Metastatic Breast Cancer Patients Treated with CDK4/6 Inhibitors: A Novel Biomarker

Objective

Hormone positive breast cancer is a tumor with high mortality. Combining antihormonal therapy with cyclin dependent kinase 4/6 inhibitors (CDK4/6i) has resulted in longer survival. The effect of inflammatory parameters such as c-reactive protein and c-reactive protein/lymphocyte ratio (CLR) on efficacy and survival in CDK4/6i treatment is unknown. In our study, we aimed to investigate the role of CLR and some parameters in predicting progression-free survival (PFS) with CDK4/6i.

Methods

This retrospective cohort study included 78 patients with denovo and recurrent metastatic breast cancer treated with CDK4/6i. Cut off values for the prediction of mortality by various numerical parameter scores were performed by ROC Curve analysis. The effect of clinical variables, inflammatory and histopathological parameters on survival was analyzed by Kaplan-Meier method.

Results

Neutrophil/lymphocyte ratio (NLR) and CLR were statistically significant in predicting mortality (p < 0.05). Ki67 and CLR were correlated with PFS. Age and CLR were correlated with OS (p < 0.05). CLR was statistically significant for both PFS (p = 0.022) and OS (p = 0.006).

Conclusion

In patients with metastatic hormone-positive breast cancer using CDK4/6i, low CLR and low Ki67 were correlated with longer PFS duration.

Palbociclib in Older Patients with Advanced/Metastatic Breast Cancer: A Systematic Review

BACKGROUND

Palbociclib in combination with endocrine therapy is approved for treatment of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer. In addition to clinical trials, several real-world studies have evaluated the effectiveness of palbociclib. With increased life expectancy in the general population, breast cancer in older women is also expected to increase.

OBJECTIVE

The aim was to systematically review evidence from both clinical trials and real-world studies for palbociclib treatment outcomes in older patients with HR+/HER2- advanced/metastatic breast cancer (a/mBC). Older patients are often underrepresented in clinical trials, and real-world evidence (RWE) will enrich the analysis of palbociclib outcomes in this subgroup of patients.

DESIGN

A systematic literature search in PubMed, EMBASE, and Cochrane Library through May 4, 2023, yielded 2355 unique articles. A total of 52 articles (13 and 39 articles reporting results from seven randomized controlled trials [RCTs] and 37 RWE studies, respectively) were included based on study eligibility criteria.

RESULTS

All RCTs used age cutoffs of ≥ 65 years to define older population (n = 722; 437 received palbociclib); all RWE studies, except one with an age cutoff of > 60 years, had age cutoffs of ≥ 65 years or higher to define older population (n = 9840; 7408 received palbociclib). Overall, in studies that compared efficacy (progression-free survival [seven RCTs, 20 RWE studies], overall survival [four RCTs, 11 RWE studies], tumor response [three RWE studies], and clinical benefit rate [one RCT, two RWE studies]) and safety outcomes (three RCTs, three RWE studies) between older and younger patients, palbociclib showed similar benefits, regardless of age. Results from two RCTs and two RWE studies showed that global quality of life (QoL) was maintained in older patients receiving palbociclib. Overall, palbociclib dose modifications (two RWE studies), dose reductions (one RCT, seven RWE studies), and treatment discontinuation rates (three RCTs, three RWE studies) were higher in older patients compared with younger patients; however, these differences did not appear to adversely impact efficacy outcomes.

CONCLUSIONS

In this systematic review, data from RCTs showed that palbociclib was effective, well tolerated, and maintained QoL in older patients with HR+/HER2- a/mBC. Palbociclib treatment in older patients in real-world settings was associated with similar clinical benefit as in RCTs.

PROSPERO REGISTRATION

CRD42023444195.

Real-World Experience among Elderly Metastatic Breast Cancer Patients Treated with CDK4/6 Inhibitor-Based Therapy

The largest portion of breast cancer patients diagnosed after 70 years of age present with hormone receptor-positive (HR+) breast cancer subtypes. Cyclin-dependent kinase (CDK) 4/6 inhibitor treatment, in conjunction with endocrine therapy, has become standard-of-care for metastatic HR+ breast cancer. In total, 320 patients with metastatic breast cancer receiving CDK4/6 inhibitor combined with fulvestrant or an aromatase inhibitor were enrolled in an ongoing observational study or were included in an IRB-approved retrospective study. All patients receiving CDK4/6 inhibitor-based therapy that were ≥70 years of age (n = 111) displayed prolonged progression-free survival (27.6 months) as compared to patients <70 years of age (n = 209, 21.1 months, HR = 1.38, p < 0.05). Specifically, patients receiving a CDK4/6 inhibitor with an aromatase inhibitor who were ≥70 years of age (n = 79) displayed exceptionally prolonged progression-free survival (46.0 months) as compared to patients receiving the same treatment who were <70 years of age (n = 161, 21.8 months, HR = 1.71, p < 0.01). However, patients ≥70 years of age also experienced more frequent adverse responses to CDK4/6 inhibitor-based treatment leading to dose reduction, hold, or discontinuation than the younger cohort (69% and 53%, respectively). Treatment strategies that may decrease toxicity without affecting efficacy (such as dose titration) are worth further exploration.

Treatment patterns of patients with HR+/HER2- metastatic breast cancer receiving CDK4/6 inhibitor-based regimens: a cohort study in the French nationwide healthcare database

PURPOSE

To assess real-world treatment patterns in patients diagnosed with hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) metastatic breast cancer (mBC) who received cyclin-dependent kinase 4/6 (CDK4/6) inhibitors in combination with an aromatase inhibitor (AI) or fulvestrant at first line.

METHODS

Patient characteristics, treatment history, and outcomes data were extracted from the French 'Système National des Données de Santé' (SNDS) database for patients diagnosed with HR+/HER2- mBC between January 2014 and June 2019 and who received combination therapy with a CDK4/6 inhibitor and endocrine therapy. Kaplan-Meier methodology was used to assess time to next treatment (TTNT) and time to treatment discontinuation (TTTD).

RESULTS

The cohort comprised 6061 patients including 4032 patients who received CDK4/6 inhibitors + AIs and 2029 patients who received CDK4/6 inhibitors + fulvestrant. Median follow-up was 13.5 months (IQR 9.5-18.1). The median TTTD of first line treatment with CDK4/6 inhibitors + AIs and CDK4/6 inhibitors + fulvestrant was 17.3 months (95% CI 16.8-17.9) and 9.7 months (95% CI 9.0-10.2), respectively. Chemotherapy was the most common second line therapy. Median TTTD of subsequent treatment lines was progressively shorter following first line treatment with CDK4/6 inhibitors + AIs (2nd line: 4.6 months (95% CI 4.4-4.9) and with CDK4/6 inhibitors + fulvestrant (2nd line: 4.7 months (95% CI 4.3-5.1). TTNT was longer than TTTD across lines of therapy.

CONCLUSION

This real-world analysis confirms the effectiveness of CDK4/6 inhibitor-based regimens in French patients and highlights the frequent use of chemotherapy as second line therapy.

Radiomic predicts early response to CDK4/6 inhibitors in hormone receptor positive metastatic breast cancer

The combination of Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) and endocrine therapy (ET) is the standard of care for hormone receptor-positive (HR + ), human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). Currently, there are no robust biomarkers that can predict response to CDK4/6i, and it is not clear which patients benefit from this therapy. Since MBC patients with liver metastases have a poorer prognosis, developing predictive biomarkers that could identify patients likely to respond to CDK4/6i is clinically important. Here we show the ability of imaging texture biomarkers before and a few cycles after CDK4/6i therapy, to predict early response and overall survival (OS) on 73 MBC patients with known liver metastases who received palbociclib plus ET from two sites. The delta radiomic model was associated with OS in validation set (HR: 2.4; 95% CI, 1.06-5.6; P = 0.035; C-index = 0.77). Compared to RECIST response, delta radiomic features predicted response with area under the curve (AUC) = 0.72, 95% confidence interval (CI) 0.67-0.88. Our study revealed that radiomics features can predict a lack of response earlier than standard anatomic/RECIST 1.1 assessment and warrants further study and clinical validation.

Clinical impact of body mass index on palbociclib treatment outcomes and effect on exposure

The impact of body mass index (BMI) on treatment outcomes in patients with cancer is gaining increasing attention given the limited data available. The aim of this study was to investigate the contribution of BMI on the safety and efficacy profile of palbociclib in 134 patients with metastatic luminal-like breast cancer treated with palbociclib and endocrine therapy (ET). Normal-weight and underweight patients (BMI<25) were compared with overweight and obese (BMI≥25). Detailed clinical and demographic data were collected. Patients with a BMI<25 had a higher incidence of relevant-hematologic toxicities (p = 0.001), dose reduction events (p = 0.003), and tolerated lower dose intensities (p = 0.023) compared to patients with a BMI≥25. In addition, patients with a BMI<25 had significantly shorter progression-free survival (log-rank p = 0.0332). A significant difference was observed in the subgroup of patients for whom systemic palbociclib concentrations were available: patients with a BMI<25 had a 25% higher median minimum plasma concentrations (C_min) compared to BMI≥25. This study provides compelling evidence for a clinically relevant contribution of BMI in discriminating a group of patients who experienced multiple toxicities that appeared to affect treatment adherence and lead to poorer survival. BMI could become a valuable tool for personalizing the starting dose of palbociclib to improve its safety and efficacy.

The Challenges of Treating Patients with Breast Cancer and Obesity

Obesity is defined as a body mass index (BMI) of 30 kg/m2 or more and is associated with worse outcomes in patients with breast cancer, resulting in an increased incidence of breast cancer, recurrence, and death. The incidence of obesity is increasing, with almost half of all individuals in the United States classified as obese. Patients with obesity present with unique pharmacokinetics and physiology and are at increased risk of developing diabetes mellitus and cardiovascular disease, which leads to specific challenges when treating these patients. The aim of this review is to summarize the impact of obesity on the efficacy and toxicity of systemic therapies used for breast cancer patients, describe the molecular mechanisms through which obesity can affect systemic therapies, outline the existing American Society of Clinical Oncology (ASCO) guidelines for treating patients with cancer and obesity, and highlight additional clinical considerations for treating patients with obesity and breast cancer. We conclude that further research on the biological mechanisms underlying the obesity-breast cancer link may offer new treatment strategies, and clinicals trials that focus on the treatment and outcomes of patients with obesity and all stages of breast cancer are needed to inform future treatment guidelines.

Racial disparities in overall survival after the introduction of cyclin-dependent kinase 4/6 inhibitors for patients with hormone receptor-positive, HER2-negative metastatic breast cancer

PURPOSE

CDK4/6 inhibitors (CDK4/6i) combined with endocrine therapy have improved HR + /HER2- metastatic breast cancer (MBC) outcomes. However, it is still unclear whether the response to CDK4/6i is similar for all races. Therefore, we aimed to assess overall survival (OS) trends stratified by race in patients with HR + /HER2- MBC after the approval of CDK4/6i, as part of the standard of care, in 2015.

METHODS

We performed a population-based study using the SEER database. Patients with HR + /HER2- MBC were divided into two time-based cohorts: 1) pre-CDK4/6i era (diagnosed in 2011-2013) and 2) post-CDK4/6i era (diagnosed in 2015-2017). We used propensity score matching and identified 2,684 patients in each cohort that matched in several characteristics. Kaplan-Meier methods were used to estimate 2-year OS. Association between cohort and OS was evaluated using marginal Cox proportional hazards models with robust sandwich variance estimator. We conducted competing risk analysis to estimate the risk of breast cancer death in both cohorts.

RESULTS

The 2-year OS rate was 65% for the post-CDK4/6i era and 62% for the pre-CDK4/6i era (stratified log-rank p = 0.025). The 2-year OS for non-Hispanic White (NHW) patients improved in the post-CDK4/6i era compared to the pre-CDK4/6i era (67% vs. 63%, p = 0.033). However, OS did not improve for non-Hispanic Black (NHB) (54% vs. 54%, p = 0.876) or Hispanic (67% vs. 65%, p = 0.617) groups. The risk of breast cancer death decreased in the post-CDK4/6i era as compared to the pre-CDK4/6i era (2-year risk of breast cancer death: 33% vs. 30%, p = 0.015); however, this effect was observed only in NHW (sHR 0.84, p = 0.005) women, but not in NHB (sHR 0.94, p = 0.630) or Hispanic (sHR 0.91, p = 0.550) women.

CONCLUSIONS

Our study confirms that outcomes for HR + /HER2- MBC have improved after CDK4/6i were introduced in 2015. However, this effect is primarily driven by the improved OS in NHW patients, without significant improvement in OS in NHB or Hispanics.

HR+/HER2- de novo metastatic breast cancer: a true peculiar entity?

De novo metastatic breast cancer (dnMBC) accounts for ~6-10% of all breast cancers and for ~30% of MBC with increasing incidence over time. Hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR⁺/HER2^-) tumours are the most frequent subtype with a similar incidence to that observed amongst recurrent MBC (rMBC). Higher frequency of PI3KCA and ARID2 mutations and a lower frequency of ESR1 mutations and of genes involved in DNA damage, as compared with rMBC, have been reported in HR⁺/HER2^- dnMBC; however, these are not correlating with prognosis, whilst tumour mutational burden is inversely correlated with outcome. Bone represents the most frequent metastatic site, being the single site in up to 60% of patients with dnMBC. HR⁺/HER2^- dnMBC has been generally reported to have better outcomes than rMBC, with a median overall survival ranging from 26 months to nearly 5 years in patients with favourable features such as age <40 years and bone-only disease, but not when compared with patients with late recurring disease (≥2-5 years). Analyses of the de novo cohorts within randomized clinical trials and large real-world series report a better outcome after treatment with CDK4/6 inhibitors and endocrine agents as compared to rMBC. Despite the limitations of retrospective studies and controversial results of the randomized trials, locoregional treatment of the primary tumour after response to systemic therapy appears to confer a survival benefit, particularly in patients with favourable prognostic factors. Altogether genomic, biological and clinical findings highlight HR⁺/HER2^- dnMBC as a peculiar entity as compared with rMBC and deserve a dedicated treatment algorithm. This article is part of the Tackling clinical complexity in breast cancer Special Issue: https://www.drugsincontext.com/special_issues/tackling-clinical-complexity-in-breast-cancer/.