Progression-Free Survival for Real-World Use of Palbociclib in Hormone Receptor-Positive Metastatic Breast Cancer

Patterns and outcomes in HR+/HER2- advanced/metastatic breast cancer patients in Brazil receiving palbociclib

Aim: To outline the demographic and clinical features, treatment approaches and clinical outcomes of patients treated with palbociclib as the initial therapy for HR+/HER2- advanced or metastatic breast cancer (aBC/mBC) in private healthcare facilities in Brazil.Materials & methods: This study involved a retrospective review conducted from June 2022 to May 2023.Results: The study included 121 patients, with an average age of 54.4 years, and 82 (67.7%) were menopausal at the time of diagnosis. Of these, 51 patients (42.1%) were treated with palbociclib and fulvestrant, while 67 patients (55.8%) received palbociclib and aromatase inhibitors. Most patients (65.3%) did not need to adjust their doses. The progression-free survival rates were 78% at 6 months and 60% at 12 months. Overall survival rates were 86% at 6 months and 70% at 12 months.Conclusion: Palbociclib combinations show promising effectiveness in managing HR+/HER2- advanced or metastatic breast cancer.

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.

The role of CDK4/6 inhibitors in older and younger patients with breast cancer: A systematic review and meta-analysis

INTRODUCTION

Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors have an extremely important impact on the treatment of hormone-sensitive breast cancer (BC) and have radically changed the first-line treatment for metastatic disease with increased rates of treatment response, overall survival (OS), and progression-free survival (PFS). We performed a pooled analysis of randomized trials to validate or refute the hypothesis that there is a significant survival benefit of adding anti-CDK4/6 inhibitors to standard endocrine therapy (ET) in older patients with advanced BC.

METHODS

We selected only English-language phase II/III randomized controlled trials that compared ET alone with ET with anti-CDK4/6 inhibitors in the treatment of advanced BC, with subgroups reporting the outcomes of elderly patients (usually at least 65 years). The primary endpoint was OS.

RESULTS

The review process led to the inclusion of 12 articles and two meeting abstracts, including a total of 10 trials. The addition of CDK4/6 inhibitors to ET (letrozole or fulvestrant) significantly reduced mortality risk by 20% in younger patients (fixed-effect model; HR 0.80; 95% CI 0.72-0.9; p < 0.01) and 21% in older BC patients (HR 0.79; 95% CI 0.69-0.91; p < 0.01). No OS data were available for patients ≥70 years.

CONCLUSION

This large, pooled analysis is the first to demonstrate that CDK4/6 inhibitors confer OS and PFS benefits in elderly patients (those aged ≥65 years) with advanced ER + BC and to indicate that it should be discussed with and offered to all patients after geriatric assessment and according to the toxicity profile.

Cyclin-dependent kinase 4/6 inhibitor treatment use in women treated for advanced breast cancer: Integrating ASCO/NCODA patient-centered standards in a community pharmacy

BACKGROUND

Outpatients treated with oral anti-cancer drugs, including selective cyclin-dependent kinase 4/6 inhibitors (CDK4/6i), may benefit from a pharmacy practice setting adapted to support proper oral anti-cancer drug monitoring. This real-world study aimed to characterize patient-centered pharmacy practice aligned with American Society of Clinical Oncology (ASCO)/National Community Oncology Dispensing Association (NCODA) standards and to describe its impact on CDK4/6i treatment use.

METHODS

This retrospective study included women with confirmed hormone receptor-positive/human epidermal growth factor 2 negative locally advanced or metastatic breast cancer treated with either palbociclib, abemaciclib or ribociclib combined with letrozole or fulvestrant. Pharmacists collected patient characteristics, clinical activities, and treatment patterns using data from the pharmacy chart. CDK4/6i treatment adherence rates were estimated based on medication claims data. Time-to-treatment discontinuation, a proxy for time-to-event, was assessed using the Kaplan-Meier estimate.

RESULTS

Of the 195 patients assessed for eligibility, 65 were included in this study. The median observation duration was 13.6 months. An average of seven pharmaceutical care activities (range 2.8-21.7) per patient was documented for each treatment cycle. The mean proportion of days covered was 89.6%. The median time-to-treatment discontinuation was estimated at 44.2 months in patients treated with CDK4/6i + letrozole and 17.0 months in patients treated with CDK4/6i + fulvestrant. The average relative dose intensity was 85%, and the benefits of treatment were maintained regardless of the relative dose intensity levels.

CONCLUSION

A structured patient-centered pharmacy practice model integrating the ASCO/NCODA patient-centered standards and ongoing communication with patients and healthcare providers ensure timely refills, close monitoring, and allows patients to achieve high adherence and persistence rates comparable to those reported in clinical trials.

Effectiveness of palbociclib with aromatase inhibitors for the treatment of advanced breast cancer in an exposure retrospective cohort study: implications for clinical practice

BACKGROUND

New drugs for locally advanced or metastatic breast cancer have led to clinical benefits, aside with increasing costs to healthcare systems. The current financing model for health technology assessment (HTA) privileges real-world data. As part of the ongoing HTA, this study aimed to evaluate the effectiveness of palbociclib with aromatase inhibitors (AI) and compare it with the efficacy reported in PALOMA-2.

METHODS

A population-based retrospective exposure cohort study was conducted including all patients initiating treatment in Portugal with palbociclib under early access use and registered in the National Oncology Registry. The primary outcome was progression free survival (PFS). Secondary outcomes considered included time to palbociclib failure (TPF), overall survival (OS), time to next treatment (TTNT), and proportion of patients discontinuing treatment due to  adverse events (AEs). The Kaplan-Meier method was used and median, 1- and 2-year survival rates were computed, with two-sided 95% confidence intervals (95%CI). STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) guidelines for reporting observational studies were used.

RESULTS

There were 131 patients included. Median follow-up was 28.3 months (IQR: 22.7-35.2) and median duration of treatment was 17.5 months (IQR: 7.8-29.1). Median PFS was 19.5 months (95%CI 14.2-24.2), corresponding to a 1-year PFS rate of 67.9% (95%CI 59.2-75.2) and a 2-year PFS rate of 42.0% (95%CI 33.5-50.3). Sensitivity analysis showed median PFS would increase slightly when excluding those not initiating treatment with the recommended dose, raising to 19.8 months (95%CI 14.4-28.9). By considering only patients meeting PALOMA-2 criteria, we could observe a major difference in treatment outcomes, with a mean PFS of 28.8 months (95%CI 19.4-36.0). TPF was 19.8 months (95%CI 14.2-24.9). Median OS was not reached. Median TTNT was 22.5 months (95%CI 18.0-29.8). A total of 14 patients discontinued palbociclib because of AEs (10.7%).

CONCLUSIONS

Data suggest palbociclib with AI to have an effectiveness of 28.8 months, when used in patients with overlapping characteristics to those used in PALOMA-2. However, when used outside of these eligibility criteria, namely in patients with less favorable prognosis (e.g., presence of visceral disease), the benefits are inferior, even though still favorable.

Real-world palbociclib effectiveness in patients with metastatic breast cancer: Focus on neutropenia-related treatment modification strategies and clinical outcomes

INTRODUCTION

In addition to clinical trials, real-world data is needed to verify the effectiveness of the CDK 4/6 inhibitor palbociclib. The primary aim was to examine real-world variation in treatment modification strategies for neutropenia and its relation to progression-free survival (PFS). The secondary aim was to assess if there is a gap between real-world and clinical trial outcomes.

MATERIALS AND METHODS

In this multicenter, retrospective observational cohort study 229 patients were analyzed who started palbociclib and fulvestrant as second- or later-line therapy for HR-positive, HER2-negative metastatic breast cancer in the Santeon hospital group in the Netherlands between September 2016 and December 2019. Data were manually retrieved from patients' electronic medical records. PFS was examined using the Kaplan-Meier method to compare neutropenia-related treatment modification strategies within the first three months after neutropenia grade 3 - 4 occurred, as well as patients' eligibility to have participated in the PALOMA-3 clinical trial or not.

RESULTS

Even though treatment modification strategies differed from those in PALOMA-3 (dose interruptions: 26 vs 54%, cycle delays: 54 vs 36%, and dose reductions: 39 vs 34%), these did not influence PFS. Patients who were PALOMA-3 ineligible experienced a shorter median PFS than those who were eligible (10.2 vs. 14.1 months; HR 1.52; 95% CI 1.12 - 2.07). An overall longer median PFS was found compared to PALOMA-3 (11.6 vs. 9.5 months; HR 0.70; 95% CI 0.54 - 0.90).

CONCLUSION

This study suggests no impact of neutropenia-related treatment modifications on PFS and confirms inferior outcomes outside clinical trial eligibility.

Palbociclib plus endocrine therapy in hormone receptor-positive and HER2 negative metastatic breast cancer: a multicenter real-world study in the northwest of China

BACKGROUND

Real-world data of Palbociclib are insufficient in China. This study aimed to investigate the treatment pattern and real-world outcomes in hormone receptor positive and human epidermal growth factor 2 receptor negative (HR+/HER2-) metastatic breast cancer (MBC) patients treated with Palbociclib in the northwest of China.

METHODS

HR+/HER2- MBC patients who received Palbociclib in 8 centers from July 2017 to September 2019 were retrospectively included in this study. Real-world objective response rate (ORR), progression-free survival (PFS) and safety profiles were analyzed. The survival curves were plotted by the Kaplan-Meier method to analyze PFS, which was verified by the log-rank test.

RESULTS

In total, 211 women were eligible for the analysis. A total of 85 patients (40.3%), 78 (37.0%), and 48 (22.7%) received Palbociclib in the first-, second-, third- or later-line setting, respectively. 46 patients achieved partial response and 145 patients experienced stable disease, with an ORR of 21.8% and a disease control rate of 90.5%. Following a median follow-up period of 14.2 months, the median PFS was 12.2 months (95% confidence interval, 10.1-14.3 m), and the median overall survival was not reached. Early Palbociclib initiation, sensitivity or acquired resistance to endocrine therapy, estrogen receptor and progesterone receptor double positivity, less than 3 metastatic sites, without visceral metastasis, bone metastasis only, without prior chemotherapy or endocrine therapy were associated with a prolonged PFS in MBC (All P < 0.05). The most common grade 3 or 4 adverse events (AE) was neutropenia (36.5%), and the most common nonhematologic AE was fatigue (10.9%). No patient experienced AE leading to treatment discontinuation.

CONCLUSION

Palbociclib plus endocrine therapy exhibited favorable effectiveness and manageable toxicities in the real-world setting, supporting their use in Chinese patients with HR+/HER2 - MBC.

Oncologists' Perspectives on Individualizing Dose Selection for Patients With Metastatic Cancer

PURPOSE

Treatment goals for patients with metastatic cancer include prolongation and maintenance of quality of life. Patients and oncologists have questioned the current paradigm of initial dose selection for systemic therapy; however, data on oncologists' dose selection strategies and beliefs are lacking.

METHODS

We conducted an electronic international survey of medical oncologists who treat patients with breast and/or gastrointestinal cancers. Survey questions addressed experiences with, and attitudes toward, dose reduction at initiation (DRI) of a new systemic therapy for patients with metastatic cancer.

RESULTS

Among 3,099 eligible oncologists, 367 responded (response rate 12%). Most (52%) reported using DRI at least 10% of the time to minimize toxicities. Gastrointestinal specialists were more likely to report DRI ≥ 10% of the time (72% v 50% of generalists and 51% of breast specialists, P < .005). Of those who dose reduced ≥ 10% of the time, 89% reported discussing potential tradeoffs between efficacy and toxicity with patients. Overall, 65% agreed it is acceptable to lower starting doses to reduce side effects even if it compromises efficacy; younger clinicians were more likely to agree (P < .005). There was strong support (89%) for future trials to determine optimal effective, rather than maximum tolerated, dose.

CONCLUSION

Oncology practice varies with regard to discussion and individualized selection of starting doses in the metastatic setting. This study demonstrates a need for consideration of shared decision making regarding initial dose selection and strong support among oncologists for clinical studies to define optimal dosing and best practices for individualizing care.

Population Pharmacokinetics of Palbociclib and Its Correlation with Clinical Efficacy and Safety in Patients with Advanced Breast Cancer

Neutropenia is the most frequent dose-limiting toxicity reported in patients with metastatic breast cancer receiving palbociclib. The objective of this study was to investigate the pharmacokinetic–pharmacodynamic (PK/PD) relationships for toxicity (i.e., absolute neutrophil count, ANC) and efficacy (i.e., progression-free survival, PFS). A semi-mechanistic PK/PD model was used to predict neutrophils’ time course using a population approach (NONMEM). Influence of demographic and clinical characteristics was evaluated. Cox proportional hazards models were developed to evaluate the influence of palbociclib PK on PFS. A two-compartment model with first-order absorption and a lag time adequately described the 255 palbociclib concentrations provided by 44 patients. The effect of the co-administration of proton-pump inhibitors in fasting conditions increased palbociclib clearance by 56%. None of the tested covariates affected the PD parameters. Model-based simulations confirmed the concentration-dependent and non-cumulative properties of palbociclib-induced neutropenia, reversible after treatment withdrawal. The ANC nadir occurred approximately at day 24 of each cycle. Cox analyses revealed a trend for better PFS with increasing palbociclib exposure in older patients. By characterizing palbociclib-induced neutropenia, this model offers support to clinicians to rationally optimize treatment management through patient-individualized strategies.

The Impact of Real-World Alternative Dosing Strategies of Palbociclib on Progression-Free Survival in Patients with Metastatic Breast Cancer

Background: Palbociclib, a cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitor, in combination with letrozole or fulvestrant has been demonstrated to prolong the progression-free survival (PFS) in patients with hormone receptor-positive (HR+), human epidermal growth factor 2-negative (HER2-) metastatic breast cancer. In efforts to mitigate neutropenic toxicities, oncologists in real-world practice have prescribed alternative dosing strategies with palbociclib, yet the implication on PFS is unknown. Methods: We conducted a retrospective, observational chart review of all female patients at our clinics with HR+, HER2- metastatic breast cancer receiving palbociclib in combination with either letrozole or fulvestrant with a first dose initiated between June 2016 and December 2018 and followed their disease course until 30 April 2020. Results: The median PFS for all clinic patients receiving palbociclib and letrozole (n = 63) was 40.8 months (95% confidence interval (CI) 25.6–not estimable) and 16.97 months (95% CI 8.57–not estimable) for patients receiving palbociclib and fulvestrant (n = 11). We identified seven alternative dosing strategies prescribed by oncologists, the most prevalent being prescribing palbociclib for three weeks on and two weeks off (n = 8). The Kaplan–Meier curves for PFS in patients receiving letrozole and palbociclib prescribed alternative dosing strategies appear to diverge from monograph dosing early in the treatment. Many patients prescribed palbociclib using alternative dosing strategies continued to be observed even by the 18-month timepoint. The prevalence of grade 4 neutropenia was lower for patients on palbociclib with letrozole, suggesting a possible mitigation of severe neutropenia with alternative dosing strategies. Conclusions: We conclude that alternative dosing strategies used by oncologists such as prescribing palbociclib for three weeks on, two weeks off may achieve comparable disease control while mitigating neutropenic toxicities when compared to standard monograph dosing recommendations, prolonging treatment tolerability and adherence. Further large-scale studies are needed to confirm these results for future clinical adoption.

Barriers and facilitators to taking CDK4/6 inhibitors among patients with metastatic breast cancer: a qualitative study

PURPOSE

Most studies of adherence to treatment for breast cancer have focused on early-stage patients. Findings from these studies may not generalize to patients with metastatic breast cancer (MBC). The objective of this study was to identify barriers and facilitators of adherence to cyclin-dependent kinase 4/6 (CDK4/6) inhibitors among patients with MBC, guided by the social ecologic model (SEM).

METHODS

Patients with MBC (N = 25), their caregivers (N = 9), and oncology providers (N = 13) completed semi-structured qualitative interviews exploring their experiences with CDK4/6 inhibitors. Interviews were audio-recorded, transcribed verbatim, and analyzed by three raters using a combined deductive and inductive approach.

RESULTS

Qualitative analysis identified barriers and facilitators of adherence at each SEM level. Intrapersonal and interpersonal factors were most frequently discussed. Intrapersonal factors included knowledge/beliefs about CDK4/6 inhibitors, side effects, and establishing a routine. Interpersonal factors included effective communication with/coordination by the care team, support from family and friends, and information from other patients with MBC. Although less frequently discussed, policy factors (i.e., cost of CDK4/6 inhibitors) were of great concern to patients, caregivers, and providers.

CONCLUSION

Barriers to adherence to CDK4/6 inhibitors exist at multiple levels. Our results underscore the potential value of a multilevel intervention (e.g., patient education, evidence-based strategies for symptom management, tips for open and assertive communication with providers, information about financial resources/support available, and so on) to support adherence in this population.

Real-world effectiveness and sensitivity of palbociclib plus endocrine therapy in HR+/HER2- patients with metastatic breast cancer

Palbociclib has shown satisfactory outcomes when combined with endocrine therapy (ET) in hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (MBC). However, data in Asia are currently scarce.This retrospective study aimed to evaluate the real-world effectiveness, sensitivity, and toxicity of palbociclib plus ET in HR+/HER2- MBC in North China. We recruited patients with HR+/HER2- MBC from August 2018 to July 2020 across 7 hospitals in North China. The primary endpoint was to evaluate progression-free survival (PFS) after initial progress on palbociclib therapy. The secondary endpoints included determining predictive biomarkers of palbociclib sensitivity and toxicity of palbociclib.A total of 54 patients were analyzed in this cohort with an estimated median follow-up time of 14.3 months. Patients who received palbociclib as a first-line treatment showed significantly prolonged PFS compared with those who received palbociclib as a second-line or beyond treatment (21.8 months vs 15.9 months vs 6.8 months) (P < .001). Besides, patients with Ki67 <30% (P = .024) and PR ≥20% (P = .041) in metastatic tumors had significantly longer PFS. The Cox proportional-hazards regression analyses proved that different lines (P = .001 in multivariate analysis), Ki67 <30% (P = .035 in multivariate analysis), and PR ≥20% (P = .045 in univariate analysis) in metastatic tumors affected PFS significantly. The most common adverse events were hematologic, with 31.48% of patients having neutropenia.Palbociclib plus ET significantly prolonged PFS for patients with HR+/HER2- MBC who received first-line therapy, with manageable toxicity. The values of Ki67 and PR in metastatic tumors may be potential predictive biomarkers of palbociclib sensitivity.

Real-world benefit of combination palbociclib and endocrine therapy for metastatic breast cancer and correlation with neutropenia

BACKGROUND

Combination CDK4/6 inhibitor and endocrine therapy has been shown to significantly improve progression-free survival (PFS) in patients with hormone receptor (HR)-positive, HER2-negative metastatic breast cancer (mBC). The aim of this retrospective study was to evaluate the real-world benefit of first-line combination therapy in this cohort and to correlate treatment efficacy with neutropenia, a common toxicity of CDK4/6 inhibitors.

METHODS

This study included HR-positive, HER2-negative advanced or mBC patients who were treated with palbociclib plus endocrine therapy, mainly letrozole, between 1 January 2015 and 1 March 2018. Progression-free survival (PFS) was determined using Kaplan-Meier analysis. The predictive value of absolute neutrophil count (ANC) and neutrophil-to-lymphocyte ratio (NLR) for PFS were explored using Cox regression models. Both ANC and NLR were used as a time-dependent variable.

RESULTS

In total, 165 patients were included with median PFS of 24.19 months (95% CI 18.93-NR). Median PFS for patients with bone-only metastases (n = 54) was not reached (95% CI 18.21-NR). Among patients with all other metastases (n = 111), median PFS was 24.19 months (95% CI 16.33-33.82). Lower ANC was correlated with decreased risk of progression (HR 0.84, 95% CI 0.71-0.97, p = 0.008). There was no significant association between NLR and the risk of disease progression (HR 1.07, 95% CI 0.97-1.18, p = 0.203).

CONCLUSION

The effectiveness of palbociclib and endocrine therapy in the treatment of HR-positive, HER2-negative mBC in the real-world setting is similar to the efficacy reported in the PALOMA-2 trial. Patients with lower neutrophil count may have a lower risk of early disease progression.

Palbociclib as an early-line treatment for Japanese patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer: a review of clinical trial and real-world data

Breast cancer is the most common type of cancer among women worldwide and in Japan. The majority of breast cancers are hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2‒), and endocrine therapy is an effective therapy for this type of breast cancer. However, recent substantial advances have been made in the management of HR+/HER2‒ advanced breast cancer (ABC) with the advent of targeted therapies, such as cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, resulting in significant improvements in survival outcomes versus endocrine therapy alone. To evaluate the optimal use of palbociclib, a CDK4/6 inhibitor, in HR+/HER2- ABC, this review summarizes clinical trial and real-world data for palbociclib. In addition, current biomarker studies in palbociclib clinical research are reviewed. In Japanese patients, palbociclib was shown to be effective with a manageable safety profile, although differences were observed in the frequency of adverse event and dosing parameters. Current evidence supporting palbociclib as a first-line treatment strategy for patients with HR+/HER2‒ ABC in Asia, and specifically japan, is also discussed.

First-Line Treatment with a Cyclin-Dependent Kinase 4/6 Inhibitor Plus an Aromatase Inhibitor for Metastatic Breast Cancer in Alberta

In this analysis, we describe population-based outcomes for first-line treatment with a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) combined with an aromatase inhibitor (AI). All patients who were prescribed CDK4/6i + AI from January 2016 through June 2019 were included. Patient demographics, tumour and treatment characteristics were collected and described. Survival distributions were estimated using the Kaplan–Meier method. Multivariate analysis (MVA) was constructed to examine associations between potentially prognostic clinical variables and progression-free survival (PFS). In total, 316 patients were included. The median age was 61 years. After a median follow-up of 28.1 months, the median PFS was 37.9 months (95% CI, 26.7–NR). In the MVA, PR-negative tumour (HR, 2.37; 95% CI, 1.45–3.88; p = 0.001) and CDK4/6i dose reduction (HR, 1.51; 95% CI, 1.06–2.16; p = 0.022) predicted worse PFS. Median overall survival (OS) was not reached. The 30-month and 36-month OS rates were 74% and 68%, respectively. Of patients who progressed, 89% received second-line treatment. Median time to progression on second-line chemotherapy was 9.0 (5.8–17.6) months, and median time to progression on second-line hormonal therapy +/− targeted agent was 4.0 (3.4–8.6) months (p = 0.012). CDK4/6i + AI as first-line treatment for HR-positive, HER2-negative MBC in Alberta is justified based on favourable PFS and early OS outcomes.

Dose modifications of ribociclib and endocrine therapy for treatment of ER+ HER2- metastatic breast cancer

PURPOSE

Treatment for estrogen receptor positive (ER+), human epidermal receptor 2 negative (HER2-) metastatic breast cancer (MBC) has improved with the approval of CDK 4/6 inhibitors. Clinical trials with the CDK4/6 inhibitor ribociclib, suggest that 35% to 57.5% of the patients require a dose reduction during ribociclib treatment. Data on the possible consequences of dose reduction concerning efficacy is needed.

METHODS

A retrospective cohort study on patients with ER+ HER2- MBC from three Danish oncology departments. Data on tolerability and progression-free survival were collected from electronic health records.

RESULTS

One hundred and twenty-eight patients with ER+ HER2- MBC who initiated ribociclib treatment between 1st of January 2018 to 31st of March 2020 were included in our analysis. Of these patients, 48.4% required one or more dose reductions. Overall median PFS was 19.2 months (CI-95% 14.3-NR). Patients with one or more dose reductions did not have decreased median PFS (19.2 months, CI-95% 14.3-NR compared to 12.2 months, CI-95% 7.3-NR, p = 0.078). Frequency of adverse events were as previously reported, with grade III and IV neutropenia occurring in 45.3% and 7% of patients, respectively. Patients treated with fulvestrant versus an aromatase inhibitor and patients with lymph node involvement at baseline had lower odds of requiring a dose reduction (OR_a = 0.30, CI-95% 0.12-0.73 & OR_a = 0.41, CI-95% 0.18-0.89, respectively).

CONCLUSION

Our results indicate that dose reduction of ribociclib is safe and do not compromise the efficacy of the treatment. Furthermore, the study supports translation of results from the MONALEESA trials to patients treated in real-world clinical settings.

Ki67 and progesterone receptor status predicts sensitivity to palbociclib: a real-world study

Background

Palbociclib combined with endocrine therapy has been approved as a front-line treatment for hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer (ABC). A key challenge remains to uncover biomarkers to identify those patients who may benefit from palbociclib treatment.

Methods

We retrospectively analyzed the values of Ki67 and progesterone receptor (PR) as detected by immunohistochemistry in 81 ABC patients with palbociclib and hormone therapy treatment, and evaluated the impact on progression-free survival (PFS).

Results

In the total population, women with Ki67 ≥14% had marginally significantly shorter PFS than those with Ki67 <14% (P=0.062). Patients with Ki67 ≥30% had significantly shorter PFS than those with Ki67 <30% (P=0.048). Meanwhile, PR ≥20% was associated with longer PFS. Moreover, the change of Ki67 or PR from primary tissue to metastatic lesions was related to PFS. As for the hormone therapy subgroup, there were significant associations between Ki67 and PR levels and PFS in the aromatase inhibitors (AIs) subgroup. Patients with Ki67 ≥14% or Ki67 ≥30% had shorter PFS than those with Ki67 <14% or Ki67 <30%, respectively (P=0.024, P<0.001). Additionally, the change of Ki67 or PR from primary tissue to metastatic lesions was related to PFS. When both Ki67 and PR were considered, there were significant differences between the different cohorts. Compared with patients with Ki67 ≥14% and PR <20%, those with Ki67 <14% and PR ≥20% had significantly longer PFS. In addition, patients with Ki67 <30% and PR ≥20% had significantly longer PFS than those with Ki67 ≥30% and PR <20%. Furthermore, in the AI cohort, patients with Ki67 <14% and PR ≥20% had significantly longer PFS than those with Ki67 ≥14% and PR <20%. Women with Ki67 <30% and PR ≥20% had significantly longer PFS than those with Ki67 ≥30% and PR <20%.

Conclusions

The present study indicates that both Ki67 and PR have great impacts on palbociclib and hormone therapy and may contribute to selecting more effective partners for palbociclib.

6 versus 12 months of adjuvant trastuzumab in HER2+ early breast cancer: A systematic review and meta-analysis

BACKGROUND

Adjuvant trastuzumab improves survival outcomes of human epidermal receptor 2 positive early breast cancer patients. Currently, administration of 12 months adjuvant trastuzumab is the standard therapy. However, whether 6 months treatment is non-inferior to the standard 12 months treatment remains controversial.

METHODS

Relevant records were searched in PubMed, Cochrane Library, Web of Science, and EMBASE through Jan 14, 2020. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) for disease-free survival (DFS) and overall survival (OS) were meta-analyzed. The primary endpoint was DFS with a non-inferiority hazard margin of 1.2 and the second was OS with 1.43.

RESULTS

Three randomized clinical studies met the inclusion criteria, including 3974 patients in 6 months group and 3976 in 12 months group. HR for DFS was 1.18 (95% CI 0.97-1.44, P = .09), with the non-inferiority margin comprised in the 95% CI. HR for OS was 1.14 (95% CI 0.98-1.32, P= .08), whereas the upper limit of 95% CI did not exceed the non-inferiority hazard margin.

CONCLUSION

Our analysis failed to show that 6 months treatment was non-inferior to 12 months treatment in improving the DFS. Although the non-inferiority of the 6-month adjuvant trastuzumab treatment was found for OS, considering that breast cancer patients should receive additional systematic therapies when disease progression or relapse happens, we suggest that 12 months adjuvant trastuzumab treatment should remain the standard therapeutic strategy for patients with early human epidermal receptor 2 positive breast cancer.

Patterns of treatment and outcome of palbociclib plus endocrine therapy in hormone receptor-positive/HER2 receptor-negative metastatic breast cancer: a real-world multicentre Italian study

Background

The CDK4/6 inhibitor palbociclib combined with endocrine therapy (ET) has proven to prolong progression-free survival (PFS) in women with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC). Few data are available regarding the efficacy of such a regimen outside the clinical trials.

Patients and methods

This is a multicentre prospective real-world experience aimed at verifying the outcome of palbociclib plus ET in an unselected population of MBC patients. The primary aim was the clinical benefit rate (CBR); secondary aims were the median PFS, overall survival (OS) and safety. Patients received palbociclib plus letrozole 2.5 mg (cohort A) or fulvestrant 500 mg (cohort B).

Results

In total, 191 patients (92 in cohort A, 99 in cohort B) were enrolled and treated, and 182 were evaluable for the analysis. Median age was 62 years (range 47-79); 54% had visceral involvement; 28% of patients had previously performed one treatment line (including chemotherapy and ET), 22.6% two lines and 15.9% three. An overall response rate of 34.6% was observed with 11 (6.0%) complete responses and 52 (28.6%) partial responses. Stable disease was achieved by 78 patients (42.9%) with an overall CBR of 59.8%. At a median follow-up of 24 months (range 6-32), median PFS was 13 months without significant differences between the cohorts. When analysed according to treatment line, PFS values were significantly prolonged when palbociclib-based therapy was administered as first-line treatment (14.0 months), to decrease progressively in second and subsequent lines (11.7 and 6.7 months, respectively). Median OS was 25 months, ranging from 28.0 months in 1st line to 18.0 and 13.0 months in 2nd and subsequent lines, respectively.

Conclusions

Our data indicate that palbociclib plus ET is active and safe in HR+/HER2- MBC, also suggesting a better performance of the combinations in earlier treatment lines.

Palbociclib Plus Fulvestrant in Korean Patients from PALOMA-3 With Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer

In the PALOMA-3 trial, the median progression-free survival (PFS) was longer among patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC) treated with palbociclib plus fulvestrant than those treated with placebo plus fulvestrant. This subgroup analysis examined the efficacy and safety of palbociclib among Korean patients enrolled in PALOMA-3 (n = 43 [palbociclib group, n = 24; placebo group, n = 19]). In both groups, > 40% of patients were pre/perimenopausal at enrollment. The median PFS was significantly prolonged with palbociclib vs. placebo (12.3 [95% confidence interval (CI), 9.1-not estimable] vs. 5.4 months [95% CI, 1.9-9.2]; hazard ratio, 0.40 [95% CI, 0.19-0.83]; one-sided p =0.005), and the confirmed objective response was 21.1% and 11.8%, respectively (odds ratio, 2.0 [95% CI, 0.24-24.8]). Neutropenia was the most common adverse event associated with palbociclib. Overall, palbociclib plus fulvestrant was effective and generally safe among Korean patients with HR+/HER2- ABC, regardless of menopausal status.

Real-World Outcomes of Treating Advanced Breast Cancer Patients With Palbociclib: A Multicenter Retrospective Cohort Study in Japan-The KBCOG-14 Study

Background

Clinical studies have shown that palbociclib improves progression-free survival in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) patients with advanced breast cancer (ABC). However, there are insufficient data on its use in a real-world setting in Japan. The aim of this study was to investigate the effectiveness, predictive factors, and safety of palbociclib among Japanese patients in routine clinical practice.

Methods

Between December 1, 2017, and April 30, 2019, we recruited patients from 9 hospitals and retrospectively evaluated the data on HR+/HER2- patients with ABC who received palbociclib for at least 1 week. The correlation between time-to-treatment discontinuation (TTD) and clinical background was investigated via univariate and multivariate analyses using Cox hazards models.

Results

A total of 177 women were available for analysis. Of these patients, 58 (33%) patients were treated with palbociclib with an aromatase inhibitor and 117 (66%) patients were treated with palbociclib and a selective estrogen receptor degrader. Approximately three-fourths of the patients (n = 130, 73%) received palbociclib as third- or later-line therapy. One-third of the patients had 3 or more metastatic sites (n = 59, 33%), and one-third of the patients had liver metastasis (n = 59, 33%). The median follow-up duration at the time of data cutoff was 8.9 months, the median TTD was 6.3 months, and the median overall survival was not reached. Liver metastasis (hazard ratio [HR]: 1.54 [95% confidence interval {CI}: 1.03-2.27]), high serum lactate dehydrogenase (LDH) level (>300 U/L) (HR: 2.58 [95% CI: 1.49-4.26]), and high neutrophil-to-lymphocyte ratio (NLR) (⩾3.0) (HR: 1.76 [95% CI: 1.13-2.69]) were significantly associated with shorter TTD. The most common hematologic adverse event was neutropenia, which occurred in 93% of the patients.

Conclusion

Based on the results of the pivotal phase 3 trials, the median TTD recorded in this study was shorter than expected. Our results suggest that liver metastasis, serum LDH level, and NLR may be predictive factors for HR+/HER2- ABC treatment outcomes.

Clinical Outcomes of 130 Patients with Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer Treated with Palbociclib plus Endocrine Therapy and Subsequent Therapy: A Real-World Single-Center Retrospective Study in China

BACKGROUND This retrospective single-center study conducted in China aimed to investigate the clinical outcomes of patients with hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC) treated with palbociclib plus endocrine therapy (ET) and subsequent therapy. MATERIAL AND METHODS Eligible patients were women with HR+ and HER2- MBC who initiated palbociclib plus ET between September 2016 and August 2019 at Fudan University Shanghai Cancer Center. Clinical characteristics and efficacy data were retrospectively recorded from the electronic medical record system. RESULTS In total, 130 patients were included in the study, of whom 87.0% of patients started palbociclib on 125 mg/day, 8.5% of patients had dose reduction, and 2.3% of patients discontinued the treatment because of toxicity. Overall, the disease control rate was 77.4% and clinical benefit rate was 63.4%. After a median follow-up period of 10.6 months, the median progression-free survival was 9.2 months. There was limited efficacy in patients who received palbociclib as no less than a fourth line of ET, except for patients who added palbociclib to the ET, which they had acquired resistance to. After disease progression on palbociclib, further treatment with chemotherapy and ET had similar efficacy (P=0.571). CONCLUSIONS The findings from this real-world single-center study in China showed that treatment with palbociclib plus ET exhibited favorable efficacy and good tolerance in patients with HR+ and HER2- MBC, even in patients who were initially resistant to endocrine therapy, and there was no difference in outcomes between subsequent treatment with chemotherapy and ET.

Real-World Clinical Data of Palbociclib in Asian Metastatic Breast Cancer Patients: Experiences from Eight Institutions

Purpose

Use of cyclin-dependent kinase 4/6 inhibitors improved survival outcome of hormone receptor (HR) positive metastatic breast cancer (MBC) patients, including Asian population. However, Asian real-world data of palbociclib is limited. We analyzed the real-world clinical practice patterns and outcome in HR-positive, MBC Asian patients treated with palbociclib.

Materials and Methods

Between April 2017 to November 2019, 169 HR-positive, human epidermal growth factor-2–negative MBC patients treated with letrozole or fulvestrant plus palbocilib were enrolled from eight institutions. Survival outcome (progression-free survival [PFS]), treatment response and toxicity profiles were analyzed.

Results

Median age of letrozole plus palbociclib (145 patients, 85.8%) and fulvestrant plus palbociclib (24 patients, 14.2%) was 58 and 53.5 years, with median follow-up duration of 14.63 months (range 0.2 to 33.9 months). Median PFS (mPFS) of letrozole plus palbociclib and fulvestrant plus palbociclib was 25.6 (95% confidence interval [CI], 19.1 to not reached) and 6.37 months (95% CI, 5.33 to not reached), comparable to previous phase 3 trials. In letrozole plus palbociclib arm, luminal A (hazard ratio, 2.86; 95% CI, 1.20 to 6.80; p=0.017) and patients with good performance (Eastern Cooperative Oncology Group 0–1 [hazard ratio, 3.68; 95% CI, 1.70 to 7.96]) showed better mPFS. In fulvestrant plus palbociclib group, chemotherapy naïve patients showed better mPFS (hazard ratio, 12.51, 95% CI, 1.59 to 99.17; p=0.017). The most common grade 3 or 4 adverse event was neutropenia (letrozole 86.3%, fulvestrant 88.3%).

Conclusion

To our knowledge, this is the first real-world data of palbociclib reported in Asia. Palbociclib showed comparable benefit to previous phase 3 trials in Asian patients during daily clinical practice.

Efficacy and safety of selective cyclin-dependent kinases 4/6 inhibitors in hormone-receptor-positive, HER2-negative advanced breast cancer - results from a real-world setting

BACKGROUND

Selective cyclin-dependent kinases 4/6 inhibitors (CDKi) have become the standard of care in patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer (ABC). We performed retrospective analysis in patients treated with CDKi in the first year of their routine clinical use in Slovenia.

METHODS

The primary goals were time-to-treatment failure (TTF) and overall survival (OS), analysed via Kaplan-Meier method, the secondary goals were clinical benefit rate (CBR) and safety.

RESULTS

Overall, 218 patients' data were evaluated. The median age was 61.8 years (30.6-84.6). The median number of previous ET lines for ABC was 2 (range 0-5). At the time of inclusion, 128 patients (58.7%) had visceral metastases, 45 patients (20.6%) had bone-only disease. At the median follow-up of 15.2 months, disease progressed in 74 patients and 60 patients died. The median TTF was 8.3 months for the whole group, 19.3, 10.3 and 5.5 months for patients treated in the first-, second- and further lines of systemic therapy, respectively. The median OS from the start of CDKi treatment was not reached in any of the groups. CBR was 59.6% for the whole group, 42.7% for further lines of therapy. The most common grade 3/4 adverse event was neutropaenia in 108 patients (49.5%), followed by an increase of hepatic aminotransferases in 13 patients (6.0%).

CONCLUSIONS

Even in the diverse real-world population treatment with CDKi in combination with ET showed clinical benefit, most prominently in the first- and second lines of systemic therapy.

Comparison of treatment-related adverse events of different Cyclin-dependent kinase 4/6 inhibitors in metastatic breast cancer: A network meta-analysis

BACKGROUND

Palbociclib, ribociclib and abemaciclib have all been approved in combination with endocrine therapy in hormone-receptor positive, HER2 negative metastatic breast cancer. While the efficacy of these drugs appears similar, differences in safety and tolerability are apparent.

METHODS

We searched PubMed and ASCO, ESMO and SABCS proceedings to identify randomized trials of palbociclib, ribociclib and abemaciclib. Data on common and serious adverse events (AE) were extracted for each approved drug. The odds ratio for each AE and the hazard ratio for progression-free survival were calculated relative to endocrine therapy alone. A network meta-analysis was then performed for each endocrine therapy backbone (aromatase inhibitor (AI) or fulvestrant) to compare ribociclib and abemaciclib to palbociclib.

RESULTS

8 trials were included in the analysis and comprised 2799 patients receiving cyclin-dependent kinase 4/6 inhibitors palbociclib: 873 patients; ribociclib: 1153 patients; abemaciclib: 773 patients. In 5 trials (1524 patients), the endocrine therapy backbone was an AI and in 3 trials (1275 patients) it was fulvestrant. Compared to palbociclib, ribociclib and abemaciclib showed significantly lower grade 3-4 neutropenia, but significantly higher GI toxicity. Treatment discontinuation was higher with abemaciclib than other drugs. Efficacy of the 3 drugs was similar. Compared to palbociclib, for AI backbone, the HR for PFS for ribociclib was 0.98 and for abemaciclib 1.02. For fulvestrant backbone, the HR were 0.88 and 0.93 respectively.

CONCLUSIONS

Palbociclib, ribociclib and abemaciclib have comparable efficacy, but differences in safety and tolerability. Abemaciclib has worse tolerability with significantly higher treatment discontinuation likely due to GI toxicity.

Impact of early dose intensity reduction of Palbociclib on clinical outcomes in patients with hormone-receptor-positive metastatic breast cancer

BACKGROUND

Palbociclib is commonly added to an aromatase inhibitor (AI) as first-line therapy in ER + HER2- metastatic breast cancer (MBC). There are no data on the effect of the relative dose intensity (RDI) of palbociclib in first-line setting on clinical outcomes. The objective of this study is to explore the association of RDI and dose reduction of palbociclib in the first-line setting with PFS.

METHODS

This is a retrospective study of ER + HER2- MBC patients who received palbociclib plus AI in first-line setting. Subjects ≥ 18 years old with MBC, who were started on palbociclib 125 mg daily, had completed ≥ 1 cycle of palbociclib, and did not progress within the first 12 weeks were eligible. Analyses were performed at 12- and 36-week landmarks (LM). RDI was defined as the total amount of palbociclib taken per the total amount planned. RDI-high-12 and RDI-low-12 cohorts were defined as patients receiving palbociclib with RDI ≥ 80% and RDI < 80% during the first 12 weeks, respectively. Reduction-12 and No-reduction-12 cohorts were defined as patients who had any dose reduction and patients who had no reduction during the first 12 weeks, respectively.

RESULTS

56 patients were eligible. Kaplan-Meier analysis from 12-week LM showed a median PFS of 17.1 months in RDI-high-12 versus 6.8 months in RDI-low-12 cohort (p = 0.0006). There was a 7.0-month improvement in median PFS in No-reduction-12 versus Reduction-12 cohort (p = 0.0638). Median PFS at 36-week LM was not reached in RDI-high-36 versus 8.6 months in RDI-low-36 cohort (p = 0.0703).

CONCLUSIONS

RDI < 80% of palbociclib during the first 12 weeks, when used in combination with an AI in first-line setting in ER + HER2- MBC, is associated with significantly shorter PFS compared to RDI ≥ 80%. There is a trend towards shorter PFS among patients with RDI < 80% versus RDI ≥ 80% at 36 weeks. A larger study is needed to validate these findings.