Real-world treatment patterns and effectiveness of palbociclib plus an aromatase inhibitor in patients with metastatic breast cancer aged 75 years or older

Overall Survival With Palbociclib and Aromatase Inhibitor Versus Aromatase Inhibitor Alone in Older Patients With HR+/HER2- Metastatic Breast Cancer

INTRODUCTION

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6is) in combination with endocrine therapy are the current standard of care for first-line (1L) treatment of hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (mBC). To investigate the effectiveness of palbociclib, the first-in-class CDK4/6i, plus an aromatase inhibitor (AI) in older patients, we compared overall survival (OS) in a Medicare population treated with 1L palbociclib + AI versus an AI alone.

METHODS

Patients aged ≥ 65 years who were diagnosed with de novo HR+/HER2- mBC from 2015 to 2019 were identified from the Surveillance, Epidemiology, and End Results (SEER)-linked Medicare database and were eligible if they initiated 1L palbociclib + AI or an AI alone. The primary endpoint was OS. Stabilized inverse probability of treatment weighting (sIPTW) was used to balance baseline patient characteristics.

RESULTS

Of 779 eligible patients, 296 received palbociclib + AI and 483 received AI alone as 1L treatment. After sIPTW, the median follow-up was 23.1 months with palbociclib + AI and 18.2 months with AI alone. Adjusted median OS was longer with palbociclib + AI versus AI alone (sIPTW: 37.6 vs. 25.5 months, HR = 0.73 [95% CI, 0.59-0.91]). In multivariable Cox proportional hazards regression, patients treated with palbociclib + AI versus AI alone had a 39% lower risk of death (HR = 0.61 [95% CI, 0.48-0.77]).

CONCLUSION

In routine US clinical practice, palbociclib + AI was associated with significantly prolonged OS versus AI alone in 1L treatment of patients aged ≥ 65 years with de novo HR+/HER2- mBC, adding to the growing body of evidence on the survival benefit of palbociclib + AI in this patient population.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT06086340.

Real-world effectiveness of CDK4/6i in first-line treatment of HR+/HER2- advanced/metastatic breast cancer: updated systematic review

Aim

Since 2021, additional real-world evidence (RWE) has emerged on the effectiveness of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) as first-line treatment of HR-positive/HER2-negative (HR+/HER2-) advanced/metastatic breast cancer (A/MBC), necessitating this updated review.

Methods

MEDLINE®, Embase®, and Cochrane Databases (07/06/2019-01/09/2024), and key congresses (2020-2024) were searched. Studies reporting first-line CDK4/6i use, over 100 participants, and progression-free survival (PFS) and/or overall survival (OS) data were included.

Results

This update included 82 unique studies, 42.7% for palbociclib, 7.3% for ribociclib, and 3.7% for abemaciclib; 46.3% assessed multiple CDK4/6i. In studies including multiple CDK4/6is, median PFS was 23.4-31.0 months for palbociclib, 19.8-44.0 for ribociclib, and 14.0-39.5 for abemaciclib. When reached, median OS was 38.0-58.0 months, 40.4-52.0 months, and 34.4 months, respectively. These real-world PFS and OS results were within the range of single-arm and CDK4/6i versus endocrine therapy (ET) studies, where CDK4/6i demonstrated greater benefits than ET alone.

Conclusion

First-line CDK4/6i RWE demonstrates significant clinical benefits in HR+/HER2- A/MBC. These data are important to guide clinical decision-making, as they include patients who are not adequately represented in clinical trials. Studies with longer follow-up are needed to assess long-term benefits of all three CDK4/6i therapies in HR+/HER2- A/MBC.

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.

Retrospective registry of patients with locally advanced/metastatic HR+/HER2- breast cancer treated in clinical practice in Andalusia

BACKGROUND

Limited data are available regarding the real-world effectiveness and safety of Cyclin Dependent Kinase 4/6 inhibitor (CDK4/6i) (palbociclib/ribociclib) just as a first-line treatment for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR + /HER2‒) metastatic breast cancer (MBC).

OBJECTIVE

To assess whether clinical or demographic characteristics limit access to first-line CDK4/6i treatment in clinical practice in the Autonomous Community of Andalusia (Spain) between November 2017 and April 2020. In addition, effectiveness will be described in an exploratory analysis.

METHODS

Physicians from 12 centers participated in selecting demographic and clinical characteristics, treatment, and outcome data from women with HR + /HER2- MBC treated with or without CDK4/6i in addition to hormonal in the first-line setting, in a 3:1 proportion. Kaplan-Meier analysis estimated progression-free rates (PFRs) and survival rates (SRs).

RESULTS

A total of 212 patients were included, of whom 175 (82.5%) were in the CDK4/6i treatment group and 37 (17.5%) were in the non-CDK4/6i treatment group (control group). Patients in the CDK 4/6i treatment group were younger (p = 0.0011), the biopsies of the metastatic site at the moment of the relapse were most commonly performed (p = 0.0454), and had multiple metastatic sites (p = 0.0025). The clinical benefit rate (CBR) was 82.3% in the CDK4/6i group and 67.8% in the control group. Median time to a progression event or death (PFS) was 20.4 months (95%CI 15.6-28) in the CDK4/6i group and 12.1 months (95%CI 7.9-not reached) in the control group.

CONCLUSIONS

Younger patients, biopsies of metastatic disease and with multiple metastatic sites were more frequently treated with CDK4/6i in our daily clinical practice.

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.

Palbociclib: Randomized Studies and Real-world Evidence as the Basis for Therapeutic Planning in Metastatic Breast Cancer

Endocrine-based combination therapy with an inhibitor of the cyclin-dependent kinases 4 and 6 (CDK4/6 inhibitors) is currently the first-line therapy of choice for patients with hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-), locally advanced or metastatic breast cancer (mBC). The efficacy and safety of the treatment with palbociclib, the first CDK4/6 inhibitor approved for this indication, have been confirmed in large randomized controlled clinical trials (RCTs) with strictly defined patient cohorts. Since then, many relevant questions about CDK4/6 inhibition with palbociclib for mBC have been investigated in RCTs and real-world studies. Based on this evidence, palbociclib is widely used in clinical practice since many years because of its efficacy and good tolerability. The aim of this review is to summarize findings from RCTs and RWE considering clinically relevant aspects such as safety, tolerability, quality of life and efficacy with a focus on specific questions and patient characteristics. A critical discussion and review of the overall evidence for endocrine-based therapy with the CDK4/6 inhibitor palbociclib can contribute to support therapy decisions in daily clinical practice.

Rationale for the Initiation, Outcomes, and Characteristics of Chemotherapy Following CDK4/6 Inhibitors in Breast Cancer: A Real-World Cohort Study

The standard therapy for hormone-receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer includes the use of cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) with endocrine therapy. The optimal post-CDK4/6i treatment sequence is unclear. This cohort study evaluated the initiation, characteristics, and outcomes of chemotherapy following CDK4/6i-based treatment. Among the 227 patients who began CDK4/6i therapy, 114 completed it. Seventy-nine female patients received further treatment, including 55 receiving chemotherapy. The average age was 60.1 years. Post-CDK4/6i chemotherapy was typically (69.1%) first-line due to an impending visceral crisis. The median progression-free survival (mPFS) was 3.0 months (range 0.5-18.9), and the median overall survival (mOS) was 8.3 months (0.5-26.1). The median OS from the end of CDK4/6i treatment was 12.4 months (1.5-26.8). In univariate analysis, neither mPFS nor mOS was associated with age, tumor grade, receptor status, Ki67 status, time from diagnosis to CDK4/6i cessation, therapy line, or CDK4/6i type. Dose reduction occurred in 12 patients (21.8%), and chemotherapy was ceased due to adverse events in 8 patients (14.6%). Chemotherapy showed limited benefit regardless of the regimen. The role of chemotherapy may evolve with broader CDK4/6i use in adjuvant treatment.

The treatment pattern of advanced HR-positive and HER2-negative breast cancer in central southern China: a hospital-based cross-sectional study

AIMS

This investigation aims to elucidate the treatment status of advanced HR+/HER2- breast cancer patients in Hunan Province of Central Southern China from November 2021 to December 2022.

METHODS

Data from 301 patients with advanced HR+/HER2- breast cancer were collected from the breast cancer investigation project in Hunan under the guidance of the Chinese Society of Clinical Oncolfogy (CSCO). The data included the clinical characteristics of patients and the status of first-line and second-line rescue treatment.

RESULTS

First-line chemotherapy and endocrine therapy for mBC accounted for 40% (121/301) and 60% (180/301) of treatments, respectively. AI (21%), AI plus CDK4/6 inhibitor (28%), and fulvestrant (24%) or fulvestrant plus CDK4/6 inhibitor (18%) were the most common first-line endocrine therapies. Taxane-based chemotherapy was the most common first-line chemotherapy (59%). Second-line chemotherapy and endocrine therapy for mBC accounted for 43% (72/166) and 57% (94/166) of treatments, respectively. Fulvestrant (23%) or fulvestrant plus CDK4/6 inhibitor (29%) were the most common second-line endocrine therapies. The prevalences of AI and AI plus CDK4/6 inhibitor decreased to 19% and 11%, respectively. T (taxane)-based chemotherapy was still the most common chemotherapy regimen (46%). Third-line chemotherapy was more prevalent than endocrine therapy (57% vs. 41%). T (taxane)-based chemotherapy was still the most common chemotherapy regimen (46%). Fulvestrant plus CDK4/6 inhibitor was the most common endocrine therapy (33%). AI, AI plus CDK4/6 inhibitor, and fulvestrant accounted for 21%, 12% and 18% of third-line endocrine therapies, respectively.

CONCLUSIONS

Compared to chemotherapy, endocrine therapy was a more favorable choice for first-line and second-line treatment for HR+/HER2- advanced breast cancer patients in Hunan Province.

Real-world experience with CDK4-6 inhibition in the old and oldest old with a diagnosis of breast cancer

This study describes characteristics, toxicity and survival in old patients with HR+/HER2-breast cancer (BC) treated with CDK4/6 inhibitors. Retrospective observational study that included patients ≥ 75 years with HR+/HER2-BC treated with CDK4/6 inhibitors between 2017 and 2021. Patients' general and cancer-related data were collected. Comprehensive Geriatric Assessment scales were gathered. Adverse events reported before each cycle were included. At the end of the follow-up period, mortality was retrospectively registered from medical records. All 19 patients (94.7% women, median age 77.9 ± 10.1) were at risk of frailty (G8 ≤ 14) and malnutrition (MNA-SF ≤ 11). Most were independent (52.7% Lawton ≥ 6), had no cognitive impairment (89.5%, MMSE ≥ 24), poor physical performance (70%, SPPB < 8; 62.5% TUG ≥ 12'') and polypharmacy (72.2%). Almost half had stage IV disease (47.1%). Palbociclib+letrozole was the most frequently prescribed treatment (36.8%). All patients developed some toxicity (94.7% hematologic, 36.8% renal) but except one, grade ≤ 2. Over the 42-month follow-up period, 10 reported progression and 8 died. The median survival time was 19.9 ± 3.4 months. Five months after starting treatment, the probability of survival was 73%. At 30 months, 53% of patients survived. We found a high risk of frailty and drug toxicity in this small sample. Most patients presented hematologic toxicity but to a low degree. The probability of survival increases with treatment.

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.