Real-world study of overall survival with palbociclib plus aromatase inhibitor in HR+/HER2- metastatic breast cancer

Real-world progression-free survival and overall survival of palbociclib plus endocrine therapy (ET) in Japanese patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer in the first-line or second-line setting: an observational study

BACKGROUND

A recent large real-world study conducted in the United States reported the effectiveness of palbociclib plus aromatase inhibitor in HR+/HER2- advanced breast cancer (ABC). However, local clinical practice and available medical treatment can vary between Japan and Western countries. Thus, it is important to investigate Japanese real-world data. This observational, multicenter study (NCT05399329) reports the interim analysis of effectiveness of palbociclib plus ET as first-line or second-line treatment for HR+/HER2- ABC by estimating real-world progression-free survival (rwPFS) and overall survival (OS) in Japanese routine clinical practice.

METHODS

Real-world clinical outcomes and treatment patterns of palbociclib plus ET were captured using a medical record review of patients diagnosed with HR+/HER2- ABC who had received palbociclib plus ET in the first-line or second-line treatment across 20 sites in Japan. The primary endpoint was rwPFS; secondary endpoints were OS, real-world overall response rate, real-world clinical benefit rate, and chemotherapy-free survival.

RESULTS

Of the 677 eligible patients, 420 and 257 patients, respectively, had received palbociclib with ET as first-line and second-line treatments. Median rwPFS (95% confidence interval) was 24.5 months (19.9-29.4) for first-line and 14.5 months (10.2-19.0) for second-line treatment groups. Median OS was not reached in the first-line group and was 46.7 months (38.8-not estimated) for the second-line group. The 36-month OS rates for de novo metastasis, treatment-free interval (TFI) ≥ 12 months, and TFI < 12 months were 80.2% (69.1-87.7), 82.0% (70.7-89.3), and 66.0% (57.9-72.9), respectively.

CONCLUSION

The addition of palbociclib to ET was effective for treating HR+/HER2- ABC in Japanese routine clinical practice.

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.

PACE: A Randomized Phase II Study of Fulvestrant, Palbociclib, and Avelumab After Progression on Cyclin-Dependent Kinase 4/6 Inhibitor and Aromatase Inhibitor for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor-Negative Metastatic Breast Cancer

PURPOSE

Cyclin-dependent kinase (CDK) 4/6 inhibitors (CDK4/6is) are an important component of treatment for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HER2-) metastatic breast cancer (MBC), but it is not known if patients might derive benefit from continuation of CDK4/6i with endocrine therapy beyond initial tumor progression or if the addition of checkpoint inhibitor therapy has value in this setting.

METHODS

The randomized multicenter phase II PACE trial enrolled patients with hormone receptor-positive/HER2- MBC whose disease had progressed on previous CDK4/6i and aromatase inhibitor (AI) therapy. Patients were randomly assigned 1:2:1 to receive fulvestrant (F), fulvestrant plus palbociclib (F + P), or fulvestrant plus palbociclib and avelumab (F + P + A). The primary end point was investigator-assessed progression-free survival (PFS) in patients treated with F versus F + P.

RESULTS

Overall, 220 patients were randomly assigned between September 2017 and February 2022. The median age was 57 years (range, 25-83 years). Most patients were postmenopausal (80.9%), and 40% were originally diagnosed with de novo MBC. Palbociclib was the most common previous CDK4/6i (90.9%). The median PFS was 4.8 months on F and 4.6 months on F + P (hazard ratio [HR], 1.11 [90% CI, 0.79 to 1.55]; P = .62). The median PFS on F + P + A was 8.1 months (HR v F, 0.75 [90% CI, 0.50 to 1.12]; P = .23). The difference in PFS with F + P and F + P + A versus F was greater among patients with baseline ESR1 and PIK3CA alterations.

CONCLUSION

The addition of palbociclib to fulvestrant did not improve PFS versus fulvestrant alone among patients with hormone receptor-positive/HER2- MBC whose disease had progressed on a previous CDK4/6i plus AI. The increased PFS seen with the addition of avelumab warrants further investigation in this patient population.

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.

CDK4/6 inhibitors: The Devil is in the Detail

PURPOSE OF REVIEW

Update on the most recent clinical evidence on CDK4/6 inhibitors (CDK4/6i) in the treatment of hormone receptor (HR)-positive, human epidermal growth factor receptor (HER)2-negative breast cancer.

RECENT FINDINGS

Over the past decade, CDK4/6i have become part of the standard of care treatment of patients with both metastatic and high-risk early HR + /HER2- breast cancers. The three available CDK4/6i (palbociclib, ribociclib and abemaciclib) have been extensively studied in combination with endocrine therapy (ET) in metastatic breast cancer (mBC) with consistent prolongation of progression free survival; however, ribociclib has emerged as the preferred first line agent in mBC given overall survival benefit over endocrine monotherapy. In early BC, abemaciclib is the only currently approved agent while ribociclib has early positive clinical trial data. Toxicities and financial burden limit the use of CDK4/6i in all patients and resource-poor settings, and optimal timing of their use in mBC remains unclear. There is considerable evidence for the use of CDK4/6i in metastatic and early HR + /HER2- breast cancer, but knowledge gaps remain, and further research is necessary to better define their optimal use.

Real-world effectiveness of palbociclib in HR+/HER2- metastatic breast cancer: a literature review

Approximately 70% of newly diagnosed breast cancers are of the HR+/HER2- subtype. For the treatment of patients with HR+/HER2- metastatic breast cancer, current guidelines recommend the use of a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) in combination with endocrine therapy. In this review we assess existing literature concerning real-world effectiveness of palbociclib. Survival outcomes in terms of progression-free survival and overall survival are discussed and compared among the included real-world studies and in relation to the phase III PALOMA trials.

The Use of Cyclin-Dependent Kinase 4/6 Inhibitors in Elderly Breast Cancer Patients: What Do We Know?

BACKGROUND

Breast cancer (BC) incidence increases with age, particularly in HR-positive/HER2-negative subtypes. Cyclin-dependent kinase 4 and 6 inhibitors (CDK 4/6is) alongside endocrine therapy (ET) have emerged as promising treatments for HR-positive/HER2-negative advanced and early BC. However, their efficacy, safety, and impact on quality of life (QoL) in older and frail patients remain underexplored.

METHODS

This position paper assesses the existing literature from 2015 to 2024, focusing on CDK4/6is use in patients aged 65 years and older with HR-positive/HER2-negative BC.

RESULTS

Our analysis methodically addresses critical questions regarding the utilization of CDK4/6is in the elderly BC patient population, organizing findings from the metastatic and adjuvant settings. In the metastatic setting, CDK4/6is significantly improve progression-free survival (PFS), paralleling benefits observed in younger patients, and suggest potential overall survival (OS) benefits, warranting further investigation. Despite an increased incidence of grade ≥ 3 adverse events (AEs), such as neutropenia and asthenia, CDK4/6is present a markedly lower toxicity profile compared to traditional chemotherapy, with manageable side effects. QoL analysis indicates that integrating CDK4/6is into treatment regimens does not significantly impact elderly BC patients' daily life and symptom management. Special attention is given to frail subgroups, and personalized approaches are recommended to balance efficacy and adverse effects, such as starting with ET alone and introducing CDK4/6is upon progression in patients with a low disease burden. Transitioning to the adjuvant setting, early results, particularly with abemaciclib, indicate positive effects on disease-free survival (DFS), emphasizing the need for continued analysis to validate these findings and assess long-term implications. However, data on older patients are insufficient to conclude whether they truly benefit from this treatment.

CONCLUSION

Overall, CDK4/6is present a favorable benefit-risk profile in older BC patients, at least in advanced BC; however, further research is warranted to optimize treatment strategies and improve outcomes in this population.

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 Treatment Patterns and Clinical Outcomes among Patients Receiving CDK4/6 Inhibitors for Metastatic Breast Cancer in a Canadian Setting Using AI-Extracted Data

Cyclin-dependent kinase 4/6 inhibitors (CDK4/6i) are widely used in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) advanced/metastatic breast cancer (ABC/MBC) in first line (1L), but little is known about their real-world use and clinical outcomes long-term, in Canada. This study used Pentavere's previously validated artificial intelligence (AI) to extract real-world data on the treatment patterns and outcomes of patients receiving CDK4/6i+endocrine therapy (ET) for HR+/HER2- ABC/MBC at Sinai Health in Toronto, Canada. Between 1 January 2016 and 1 July 2021, 48 patients were diagnosed with HR+/HER2- ABC/MBC and received CDK4/6i + ET. A total of 38 out of 48 patients received CDK4/6i + ET in 1L, of which 34 of the 38 (89.5%) received palbociclib + ET. In 2L, 12 of the 21 (57.1%) patients received CDK4/6i + ET, of which 58.3% received abemaciclib. In 3L, most patients received chemotherapy (10/12, 83.3%). For the patients receiving CDK4/6i in 1L, the median (95% CI) time to the next treatment was 42.3 (41.2, NA) months. The median (95% CI) time to chemotherapy was 46.5 (41.4, NA) months. The two-year overall survival (95% CI) was 97.4% (92.4, 100.0), and the median (range) follow-up was 28.7 (3.4-67.6) months. Despite the limitations inherent in real-world studies and a limited number of patients, these AI-extracted data complement previous studies, demonstrating the effectiveness of CDK4/6i + ET in the Canadian real-world 1L, with most patients receiving palbociclib as CDK4/6i in 1L.

Clinical and Genotypic Insights Into Higher Prevalence of Palbociclib Associated Neutropenia in Asian Patients

BACKGROUND

CDK4/6 inhibitors (CDK4/6i) have shown great efficacy in prolonging progression-free survival and is the current standard of care for hormone positive (HR(+)) metastatic breast cancer (mBC). Despite well tolerability and ease of use, the most common side effect of CDK4/6i is myelosuppression, with neutropenia the most prevalent adverse effect. Studies show that the prevalence and severity of neutropenia are more marked in Asian patients, although details remain obscure.

METHODS

In this study, we retrospectively analyzed 105 Taiwanese patients who received palbociclib for HR(+) HER2(-) mBC at the Taipei Veterans General Hospital. To investigate a possible genetic association for high prevalence of neutropenia, we queried the Taiwan Biobank with publicly available germline databases (ALFA, gnomAD, ExAC, 1000 Genomes project, HapMap), for the allele frequencies of 4 neutropenia-related SNPs (ABCB1_rs1045642, ABCB1_rs1128503, ERCC1_rs3212986, ERCC1_rs11615) and compared between different ethnicities. In addition, one of the patients was a long-term patient with peritoneal dialysis. We quantified the levels of palbociclib in her serum and peritoneal fluid by liquid chromatography-mass spectrometry (LC-MS).

RESULTS

Interestingly, in our cohort, early neutropenia nadir (occurred within 56 days of start) was associated with worse treatment outcome, while occurrence of grade 3/4 neutropenia was associated with better outcome. We observed an extremely high incidence of neutropenia (96.2% any grade, 70.4% grade 3/4). In the analyzed germline databases, we discovered a higher SNP frequency of the T allele in ABCB1_rs1128503, a lower frequency of T allele in ABCB1_rs1045642, and a higher SNP frequency of G allele in ERCC1_rs11615. We observed that palbociclib levels in peritoneal dialysate ranged from around 20-50 ppb, and serum levels reached 100-110 ppb during drug administration and decreased to <10 ppb during discontinuation.

CONCLUSION

Our retrospective analysis of real world palbociclib use reveals an association with grade 3/4 neutropenia with better outcome and early neutropenia nadir with worse outcome. Our findings of Asian specific SNPs support a predisposition toward profound and prevalent neutropenia in Asian patients under CDK4/6i. We also report the first pharmacokinetics analysis on a patient with peritoneal dialysis receiving CDK4/6i. In summary, our study provides novel clinical and genotypic insights into CDK4/6i associated neutropenia.

Recommendations for cyclin‑dependent kinase 4/6 inhibitor treatments in the context of co‑morbidity and drug interactions (Review)

Breast cancer is most frequently diagnosed among women aged 65-74 years and the prevalence of comorbidities in elderly patients with breast cancer is 32.2%. In addition, polypharmacy is quite common in these patients. Understanding the interaction between breast cancer treatment modalities and comorbidities is important, particularly in elderly patients, as comorbidities affect the choice of appropriate treatment and are independent risk factors for survival. A total of three oral cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i), palbociclib, ribociclib and abemaciclib, notably prolonged progression-free survival when combined with endocrine therapy (ET), compared with ET alone in patients with advanced breast cancer (ABC). The present review article therefore addressed the safety, tolerability and toxicity of CDK4/6i treatment in ABC management, compiled real-world data on how multiple clinical and pharmacological features may affect the choice of these drugs and provided practical recommendations for clinical approaches. Before starting treatment with CDK4/6i drugs, all ongoing medical conditions should be inventorized and re-graded, and examination should be performed for any additional disease that the patient may not be aware of. It is also important to obtain a detailed history of concomitant drugs, including prescription and over-the-counter drugs, vitamins, supplements and herbal products. In addition, patients should be advised to consult their oncologist before starting any new medication.

Real-world comparative effectiveness of palbociclib plus aromatase inhibitor in HR+/HER2- metastatic breast cancer

Aim: Provide real-world data on palbociclib as evidence of effectiveness in patient populations from routine clinical practice. Methods: This was a retrospective, observational cohort study of patients with HR+/HER2- metastatic breast cancer treated with palbociclib plus aromatase inhibitor (AI) or AI alone as first-line therapy within the US Oncology Network. Results: Patients treated with palbociclib plus AI (n = 838) versus AI alone (n = 450) had a numerically longer median overall survival (42.1 vs 35.7 months; hazard ratio [HR] = 0.90 [95% CI: 0.75-1.07]; p = 0.117) and a significantly extended real-world progression-free survival (21.0 vs 15.7 months; HR = 0.75 [95% CI: 0.64-0.88]; p = 0.0002) after normalized inverse probability treatment weighting. Conclusion: These real-world results support the use of palbociclib plus AI as first-line treatment in routine clinical practice for patients with HR+/HER2- metastatic breast cancer.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

The efficacy of palbociclib and ribociclib in the first-line treatment of metastatic hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer in male patients: a Turkish oncology group (TOG) study

INTRODUCTION

Male breast cancer, comprising approximately 1% of all breast cancer cases, often leads to the exclusion of male patients as a criterion in clinical trials. While the efficacy of Cyclin-dependent kinases 4 and 6 (CDK 4/6) inhibitors has been established in metastatic hormone receptor-positive (HR +) and human epidermal growth factor receptor 2-negative (HER2 -) breast cancer in women, limited data exist on their effectiveness in male patients. We aimed to evaluate the efficacy and safety of palbociclib or ribociclib in male patients with breast cancer.

METHODS

This study is a multicenter, retrospective study. We included male patients with HR + and HER2-metastatic breast cancer who received palbociclib or ribociclib as first-line treatment. Our primary endpoints were progression-free survival (PFS), overall response rates (ORR), and drug-related adverse effects.

RESULTS

A total of 46 male patients from 27 institutions were enrolled. The median age at initiation of CDK 4/6 inhibitors was 63.64 ± 13.69 years, with a median follow-up of 21.33 (95% CI 14.92-27.74) months. The ORR were 84% for palbociclib and 76.2% for ribociclib. The mPFS for the entire cohort was 28.06 months (95% CI 18.70-37.42). No significant difference in PFS was observed between palbociclib and ribociclib (mPFS: 24.46 months (95% CI 11.51-37.42) vs 28.33 months (95% CI 14.77-41.88), respectively, p = 0.211). No new adverse events were reported.

DISCUSSION

This study demonstrates that palbociclib and ribociclib are effective and safe options for first-line treatment in male patients with HR + /HER2 - metastatic breast cancer. However, further prospective studies are warranted to establish their efficacy in this population.

Real-world treatment patterns for palbociclib plus an aromatase inhibitor, or an aromatase inhibitor alone, for patients with metastatic breast cancer in the Flatiron Database

There are limited real-world comparative effectiveness data for palbociclib plus an aromatase inhibitor (AI) as a first-line (1L) treatment examining endpoints that require long term follow-up and post 1L progression. The Flatiron Health Analytic Database was used to characterize treatment and dosing patterns in patients with hormone receptor-positive/human epidermal growth factor 2-negative (HR+/HER2-) metastatic breast cancer (mBC) receiving palbociclib plus an AI vs an AI alone in routine US clinical practice. In addition, time to chemotherapy (TTC) and real-world progression-free survival (rwPFS) when combining 1L and second-line of therapy (rwPFS2) were assessed. Of 1324 patients who received palbociclib plus an AI between February 3, 2015 and March 31, 2020, 1110 (83.8%) started palbociclib at the recommended 125 mg/day dose. After stabilized inverse probability treatment-weighting (sIPTW), median TTC in patients treated with palbociclib plus an AI and AI alone was 37.4 months (95% confidence interval [CI], 33.7-40.7) and 29.2 months (95% CI, 26.8-33.5), respectively (hazard ratio [HR] = 0.77 [95% CI, 0.69-0.86], P < .0001); median rwPFS2 was 32.6 months (95% CI, 29.4-35.2) and 20.7 months (95% CI, 18.9-22.6), respectively (HR = 0.62 [95% CI, 0.54-0.70], P < .0001). Sensitivity analyses with propensity score matching showed similar results to sIPTW analyses. Results from this large real-world study examining additional effectiveness outcomes beyond 1L rwPFS and overall survival support the use of palbociclib plus an AI as a 1L treatment for patients with HR+/HER2- mBC.

Outcomes of male patients with HR+/HER2- advanced breast cancer receiving palbociclib in the real-world POLARIS study

PURPOSE

Data on treatments for male breast cancer patients are limited owing to rarity and underrepresentation in clinical trials. The real-world POLARIS study gathers data on palbociclib use for the treatment of hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC) in female and male patients. This sub-analysis describes real-world palbociclib treatment patterns, clinical outcomes, and quality of life (QoL) in male patients.

METHODS

POLARIS is a prospective, noninterventional, multicenter, real-world study of patients with HR+/HER2- ABC receiving palbociclib. Assessments included medical record reviews, patient QoL questionnaires (European Organisation for Research and Treatment of Cancer Quality-of-Life Questionnaire-Core 30), site characteristics questionnaires, and physician treatment selection surveys. Variables included demographics, disease history, global health status/QoL, clinical assessments and adverse events. Analyses were descriptive in nature. For clinical outcomes, real-world tumor responses and progression were determined by physician assessment in routine clinical practice. Real-world progression-free survival (rwPFS) was described using the Kaplan-Meier method.

RESULTS

At data cutoff, 15 male patients were enrolled (median age, 66 years). Nine patients received palbociclib as a first-line treatment and 6 as a second-line or later treatment. Patients received a median of 20 cycles of palbociclib. Neutropenia was experienced by 2 patients and grade ≥ 3 adverse events were reported in 11 patients. Global health status/QoL scores remained generally consistent during the study. One patient (6.7%) achieved a complete tumor response, 4 (26.7%) a partial response, and 8 (53.3%) stable disease. Median rwPFS was 19.8 months (95% CI, 7.4-38.0). Median follow-up duration was 24.7 months (95% CI, 20.0-35.7).

CONCLUSION

This real-world analysis showed that palbociclib was well tolerated and provides preliminary data on treatment patterns and outcomes with palbociclib in male patients with HR+/HER2- ABC, helping inform the use of palbociclib in this patient subgroup.

TRIAL IDENTIFIER

NCT03280303.

Overall survival in Japanese patients with ER+/HER2- advanced breast cancer treated with first-line palbociclib plus letrozole

BACKGROUND

An open-label, single-arm, Japanese phase 2 study (J-Ph2) investigated the efficacy and safety of first-line (1L) palbociclib (PAL) + letrozole (LET) in postmenopausal Japanese women with ER+/HER2- advanced breast cancer (ABC). In the final analysis, median progression-free survival was 35.7 months (95% CI 21.7-46.7); but overall survival (OS) data were immature. Here, we report the findings from a follow-up study of J-Ph2 (NCT04735367) evaluating OS and subsequent therapy in these Japanese women.

METHODS

Patients (N = 42) who participated in J-Ph2 were enrolled in the OS follow-up study. The primary endpoint was OS and secondary endpoints included type and duration of subsequent therapy.

RESULTS

Patients were a median age of 62.5 years; 48% had visceral metastases. At a median follow-up of 89.7 months, the median OS was 85.4 months (95% CI 64.3-not estimable). Median OS was longer in patients with nonvisceral versus visceral metastases (not reached vs 67.3 months), or with treatment-free interval > 12 months versus ≤ 12 months (85.4 vs 45.4 months), or with treatment duration ≥ 24 months versus < 24 months (not reached vs 47.5 months). Of patients who received a first subsequent therapy (81%), most (67%) continued endocrine-based therapy, while 7% received chemotherapy. The median duration of the first subsequent therapy was 8.3 months (95% CI 3.9-12.2), and the median chemotherapy-free survival was 69.1 months (95% CI 24.2-85.4).

CONCLUSIONS

In this population of Japanese women with ER+/HER2- ABC, median OS was over 7 years with 1L PAL + LET, supporting the use of 1L PAL + endocrine therapy.

TRIAL NUMBER

NCT04735367.

Disparities with influenza vaccine use in long-term survivors of metastatic breast cancer

PURPOSE

Elderly women diagnosed with metastatic breast cancer (MBC) are living longer, however their primary care management may be sub-optimal. Influenza results in preventable hospitalizations and deaths. Guidelines recommend the influenza vaccine for those > 65 years and those with cancer but use is unknown.

METHODS

A retrospective analysis was conducted using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked data. Patients were included if they were diagnosed with MBC from 1/1/2008-12/31/2017 and were ≥ 65 years of age. The primary outcome was influenza vaccine use among patients surviving ≥ 3-years. We conducted multivariable analyses using demographic and clinical factors to identify associations with vaccine use. We compared utilization to cancer-free controls.

RESULTS

We identified 1,970 patients with MBC that survived for ≥ 3 years. The median age at diagnosis was 73 years. Furthermore, 1,742 (88%) patients were White, and 153 (8%) patients were Black. Only 1,264 (64%) received an influenza vaccine at least one time and 51% received the vaccine at least two times. A multivariable model found lower odds of vaccine receipt for Black patients (OR = 0.48; 95% CI 0.34-0.68, p < 0.001) and higher odds for patients that saw primary care in the year prior to diagnosis (OR = 1.91, 95% CI 1.57-2.33, p < 0.001). Patients with MBC had lower odds of vaccine use compared to cancer free controls (OR = 0.85, 95% CI 0.74-0.97, p < 0.001).

CONCLUSION

Over 1/3 of long-term MBC survivors in our cohort did not receive the influenza vaccine. Black patients are about half as likely to be vaccinated. Given the known benefit of the vaccine, improving uptake could be an important strategy to improve outcomes.

Key Considerations for the Treatment of Advanced Breast Cancer in Older Adults: An Expert Consensus of the Canadian Treatment Landscape

The prevalence of breast cancer amongst older adults in Canada is increasing. This patient population faces unique challenges in the management of breast cancer, as older adults often have distinct biological, psychosocial, and treatment-related considerations. This paper presents an expert consensus of the Canadian treatment landscape, focusing on key considerations for optimizing selection of systemic therapy for advanced breast cancer in older adults. This paper aims to provide evidence-based recommendations and practical guidance for healthcare professionals involved in the care of older adults with breast cancer. By recognizing and addressing the specific needs of older adults, healthcare providers can optimize treatment outcomes and improve the overall quality of care for this population.

The effectiveness and safety of palbociclib and ribociclib in stage IV HR+/HER-2 negative breast cancer: a nationwide real world comparative retrospective cohort study

Introduction

Palbociclib and ribociclib are indicated in the first-line treatment of hormonal receptor-positive HER-2 negative (HR+/HER2- negative) advanced breast cancer. Although randomized-controlled trials (RCTs) proved their clinical efficacy, there are no observational studies yet to validate the clinical findings in the real-world. Therefore, this study aimed to evaluate and compare the clinical effectiveness and safety profiles of palbociclib and ribociclib in Qatar.

Materials and methods

A retrospective observational study was conducted on HR+/HER-2-negative stage-IV breast cancer patients receiving palbociclib or ribociclib in the state of Qatar. Clinical data were collected from the National Center for Cancer Care and Research (NCCCR) in Qatar using Cerner®. Primary outcomes were progression-free-survival (PFS) and overall-survival (OS) generated by Kaplan-Meier curves. Moreover, safety profiles of both two treatments were evaluated.

Results

The data from 108 patients were included in the final analysis. There was no statistically significant difference in PFS between the palbociclib and ribociclib groups; PFS was 17.85 versus 13.55 months, respectively(p> 0.05). Similarly, there was no statistically significant difference in OS between the two medications, 29.82 versus 31.72 months, respectively(p>0.05). Adverse events were similar between the two groups. Neutropenia was the most common side effect in the study population accounting for 59.3% of the patients.

Conclusions

Therefore, both treatments have similar efficacy and safety profiles. Further research on a larger-scale population and longer follow-up period is recommeneded.

Palbociclib in advanced stage hormone receptor-positive breast cancer: real-world data from a Chilean multicentre registry

Background

The addition of cyclin-dependent kinases inhibitors (CDKi) to endocrine therapy (ET) as the first- or second line treatment improves progression-free and overall survival (OS) in hormone receptor-positive, HER2 negative (HR+/HER2-) advanced stage breast cancer (ABC). Our study compared survival rates and prognostic factors in Chilean patients that used palbociclib as first or subsequent (≥second) lines of treatment in a real-world setting.

Methods

Our retrospective population-cohort study included HR+/HER2- ABC patients. We calculated 5-year OS and performed a multivariate analysis to determine prognostic factors.

Results

A total of 106 patients were included. Median age was 49 years (19-86), 28.3% (30) had de novo stage IV disease; 63% received palbociclib with ET as first line, 54% of them with aromatase inhibitor over fulvestrant. Median OS for the entire cohort was 99 months and 5-year OS was 69%. Patients that received first line palbociclib had a 5-year OS of 89% versus 43% for ET monotherapy or ≥second line palbociclib (p = 0.0062). Multivariate analysis showed that the year at diagnosis and CDKi timing (first line versus ≥second line) were significantly associated with OS.

Conclusion

Our real-world data show that first-line CDKi + ET provides a statistically significant benefit in OS versus ≥second line in HR+/HER2- ABC patients.

Palbociclib Combined with an Aromatase Inhibitor in Patients with Breast Cancer with Lung or Liver Metastases in US Clinical Practice

A cyclin-dependent kinase 4/6 inhibitor combined with endocrine therapy is the standard of care for patients with hormone receptor-positive/human epidermal growth factor 2-negative (HR+/HER2-) metastatic breast cancer (mBC), but real-world effectiveness data for patients with lung or liver metastases are limited. This retrospective study included data from the US Flatiron Health database of patients with HR+/HER2- mBC and lung or liver metastases treated with first-line palbociclib (PAL) plus an aromatase inhibitor (AI) or an AI alone in routine clinical practice. Overall survival (OS) and real-world progression-free survival (rwPFS) were assessed. A total of 891 patients were included (622 with lung metastasis, 376 with liver metastasis, and 107 with both lung and liver metastasis). After stabilized inverse probability of treatment weighting to balance patient characteristics, PAL + AI versus AI alone was associated with significantly prolonged OS (HR = 0.62; p < 0.001) and rwPFS (HR = 0.55; p < 0.001) in patients with lung metastases and numerically longer OS (HR = 0.73; p = 0.056) and significantly longer rwPFS (HR = 0.57, p < 0.001) for those with liver metastases. Overall, PAL + AI versus AI alone was associated with prolonged OS and rwPFS in routine clinical practice, supporting the use of first-line PAL + AI for patients with HR+/HER2- mBC with lung and/or liver metastases.

Clinical Impact of CDK4/6 Inhibitors in De Novo or PR- or Very Elderly Post-Menopausal ER+/HER2- Advanced Breast Cancers

The CDK4/6 inhibitors significantly increase progression-free survival (PFS) in ER+/HER2- advanced breast cancer patients. In clinical trials, overall survival (OS) improvement has been demonstrated for ribociclib and abemaciclib but not for palbociclib. We undertook a real-world evaluation of PFS and OS in 227 post-menopausal patients who received first-line CDK4/6 inhibitors. There is no significant difference in median PFS (27.5 months vs. 25.7 months, p = 0.3) or median OS (49.5 months vs. 50.2 months, p = 0.67) in patients who received either palbociclib or ribociclib, respectively. De novo disease is significantly associated with prolonged median PFS and median OS compared with recurrence disease (47.1 months vs. 20.3 months (p = 0.0002) and 77.4 months vs. 37.3 months (p = 0.0003), respectively). PR- tumours have significantly reduced median PFS and OS compared with PR+ disease (19.2 months vs. 38 months (p = 0.003) and 34.3 months vs. 62.6 months (p = 0.02), respectively). In the very elderly (>80 years), median PFS and OS are significantly shorter compared with patients who are 65 years or below (14.5 months vs. 30.2 months (p = 0.01), and 77.4 months vs. 29.6 months (p = 0.009), respectively) in the palbociclib group. Our data suggest that the benefit in the very elderly is limited, and PR+/de novo disease obtains the maximum survival benefit.

Late onset toxicities associated with the use of CDK 4/6 inhibitors in hormone receptor positive (HR+), human epidermal growth factor receptor-2 negative (HER2-) metastatic breast cancer patients: a multidisciplinary, pan-EU position paper regarding their optimal management. The GIOCONDA project

The personalization of therapies in breast cancer has favoured the introduction of new molecular-targeted therapies into clinical practice. Among them, cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors have acquired increasing importance, with the approval in recent years of palbociclib, ribociclib, and abemaciclib in combination with endocrine therapy. Currently, no guidelines are available to monitor and manage potential long-term toxicities associated with the use of these drugs. A multidisciplinary panel of European oncologists, was supported by a pharmacologist, a hematologist, a hepatologist and a pulmonologist to discuss the management of long-term toxicities, based on the literature review and their clinical experience. The panel provided detailed roadmaps to manage long-term toxicities associated with the use of CDK4/6 inhibitors in clinical practice. Knowing the frequency and characteristics of the toxicity profile associated with each CDK4/6 inhibitor is important in the decision-making process to match the right drug to the right patient.

Treatment options for patients with hormone receptor-positive, HER2-negative advanced-stage breast cancer: maintaining cyclin-dependent kinase 4/6 inhibitors beyond progression

Breast cancer is the most commonly diagnosed cancer in women worldwide. Over the past decade, the treatment paradigm for patients with metastatic breast cancer (MBC) has taken an important shift towards better survival and improved quality of life (QOL), especially for those with hormone receptor (HR)-positive diseases which represent the majority of breast cancer subtypes. The introduction of cyclin-dependent kinase 4/6 (CDK4/6) inhibitors in the upfront therapy of such patients has resulted in dramatic improvement in progression-free survival (PFS) and overall survival (OS), too. However, almost all patients would, sooner or later, develop disease progression and necessitate transition to different lines of treatment that may include chemotherapy. The idea of maintaining CDK4/6 inhibitors beyond disease progression seems attractive, as this approach has the potential to improve outcome in this setting despite the fact that the true benefit, in terms of survival, might not carry the same weight as it initially does. Researchers have been investigating potential mechanisms of resistance and identify possible biological markers for response after disease progression. Much of the available data is retrospective; however, few randomized clinical trials were recently published and few more are ongoing, addressing this point. In this paper, we intend to review the available published studies investigating the potential role for keeping CDK4/6 inhibitors in play beyond disease progression.

Real-World Effectiveness of Palbociclib Plus Aromatase Inhibitors in African American Patients With Metastatic Breast Cancer

BACKGROUND

Disparities in survival and clinical outcomes between African American and White patients with breast cancer (BC) are well documented, but African American patients have not been well represented in randomized clinical trials of CDK4/6 inhibitors. Real-world studies can provide evidence for effective treatment strategies for underreported patient populations.

PATIENTS AND METHODS

This retrospective analysis of African American patients with HR+/HER2- metastatic breast cancer (mBC) from the Flatiron Health longitudinal database evaluated treatments for patients with BC in routine clinical practice in the US. Patients initiated first-line therapy with palbociclib plus an aromatase inhibitor (AI) or AI alone between February 2015 and March 2020. Outcomes assessed included overall survival (OS) and real-world progression-free survival (rwPFS) until September 2020.

RESULTS

Of 270 eligible patients, 127 (median age 64 years) were treated with palbociclib + AI, and 143 (median age 68 years) were treated with an AI. Median follow-up was 24.0 months for palbociclib + AI and 18.2 months for AI-treated patients. Median OS was not reached (NR; 95% CI, 38.2-NR) in the palbociclib + AI group versus 28.2 months (95% CI, 19.2-52.8) in the AI group (adjusted HR, 0.56; 95% CI, 0.36-0.89; P = .013). Median rwPFS was 18.0 months (95% CI, 12.4-26.7) in the palbociclib + AI group and 10.5 months (95% CI, 7.0-13.4) in the AI group (adjusted HR, 0.74; 95% CI, 0.47-1.17; P = .199).

CONCLUSION

This comparative analysis of palbociclib + AI versus AI alone indicates that palbociclib combined with endocrine therapy in the first line is associated with improved effectiveness for African American patients with HR+/HER2- mBC in real-world settings.

TRIAL NUMBER

NCT05361655.

Abemaciclib Is Effective in Palbociclib-Resistant Hormone Receptor-Positive Metastatic Breast Cancers

Cyclin-dependent kinases 4/6 inhibitor (CDK4/6i) plus endocrine therapy (ET) is standard of care for patients with hormone receptor (HR)-positive, HER2-negative metastatic breast cancer (MBC). However, resistance to CDK4/6is plus ET remains a clinical problem with limited therapeutic options following disease progression. Different CDK4/6is might have distinct mechanisms of resistance, and therefore using them sequentially or targeting their differentially altered pathways could delay disease progression. To understand pathways leading to resistance to the CDK4/6is palbociclib and abemaciclib, we generated multiple in vitro models of palbociclib-resistant (PR) and abemaciclib-resistant (AR) cell lines as well as in vivo patient-derived xenografts (PDX) and ex vivo PDX-derived organoids (PDxO) from patients who progressed on CDK4/6i. PR and AR breast cancer cells exhibited distinct transcriptomic and proteomic profiles that sensitized them to different classes of inhibitors; PR cells upregulated G2-M pathways and responded to abemaciclib, while AR cells upregulated mediators of the oxidative phosphorylation pathway (OXPHOS) and responded to OXPHOS inhibitors. PDX and organoid models derived from patients with PR breast cancer remained responsive to abemaciclib. Resistance to palbociclib while maintaining sensitivity to abemaciclib was associated with pathway-specific transcriptional activity but was not associated with any individual genetic alterations. Finally, data from a cohort of 52 patients indicated that patients with HR-positive/HER2-negative MBC who progressed on palbociclib-containing regimens can exhibit a meaningful overall clinical benefit from abemaciclib-based therapy when administered after palbociclib. These findings provide the rationale for clinical trials evaluating the benefit of abemaciclib treatment following progression on a prior CDK4/6i.

SIGNIFICANCE

Palbociclib-resistant breast cancers respond to abemaciclib and express pathway-specific signatures of sensitivity, providing a biomarker-driven therapeutic option for patients with metastatic breast cancer following disease progression on cyclin-dependent kinases 4/6 inhibitors.

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

Background

Elderly patients are generally underrepresented in oncology clinical trials; therefore, real-world data are needed to inform clinical management of elderly patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer (mBC). This subanalysis of the P-REALITY X study (NCT05361655) evaluated palbociclib treatment patterns and comparative effectiveness of palbociclib plus an aromatase inhibitor (AI) versus an AI alone among patients with HR+/HER2- mBC aged ≥ 75 years treated in routine clinical practice in the United States.

Methods

This retrospective observational cohort study used electronic health records from the Flatiron Health Analytic Database. Palbociclib treatment patterns, overall survival (OS), real-world progression-free survival (rwPFS), and time to chemotherapy (TTC) were evaluated. Three methods were used for comparative analyses: (1) an unadjusted analysis, (2) stabilized inverse probability treatment weighting (sIPTW; primary analysis), and (3) propensity score matching (PSM; sensitivity analysis).

Results

A total of 961 patients aged ≥ 75 years with HR+/HER2- mBC were identified who started palbociclib plus an AI (n = 313) or an AI alone (n = 648) as first-line (1L) therapy between February 2015 and March 2020 (data cut-off: September 30, 2020). Among patients in the palbociclib plus an AI group with a documented palbociclib starting dose (n = 306), approximately 75% started palbociclib at 125 mg/day, and approximately 40% experienced dose adjustment. After sIPTW, patients treated with palbociclib plus an AI versus an AI alone had significantly improved OS (median of 43.0 vs. 32.4 months; hazard ratio [HR], 0.66 [95% confidence interval (CI), 0.51-0.84]; P = 0.0007), rwPFS (median of 20.0 vs. 15.0 months; HR, 0.72 (0.59-0.89); P = 0.0021), and TTC (median of 40.2 vs. 27.4 months; HR, 0.69 [0.55-0.87]; P = 0.0014). These significant improvements in OS, rwPFS, and TTC remained consistent in the unadjusted analysis and after PSM.

Conclusion

This real-world comparative analysis demonstrated that 1L palbociclib plus an AI is associated with improved effectiveness compared with an AI alone among patients with HR+/HER2- mBC aged ≥ 75 years. These findings support palbociclib plus an AI as a standard-of-care 1L treatment for elderly patients with HR+/HER2- mBC.

Indirect Treatment Comparison of First-Line CDK4/6-Inhibitors in Post-Menopausal Patients with HR+/HER2- Metastatic Breast Cancer

Background: CDK4/6-inhibitors have demonstrated similar efficacy and are considered an effective first-line endocrine treatment of patients with hormone-receptor positive (HR+)/human-epidermal-growth-factor-receptor-2 negative (HER2-) metastatic breast cancer (MBC) in the endpoint of progression-free survival (PFS). Amongst these, palbociclib was first to achieve regulatory approval, followed subsequently by ribociclib and abemaciclib. However, recent updates of overall survival (OS) showed inconsistencies in the OS benefit for palbociclib compared with the other two CDK4/6-inhibitors. With the lack of head-to-head comparison studies, our study sought to compare indirect survival outcomes between CDK4/6-inhibitors in this setting using a novel reconstructive algorithm. Methods: Phase III randomized trials comparing first-line aromatase inhibitor with/without a CDK4/6-inhibitor in post-menopausal patients with HR+/HER2- MBC were identified through systemic review and literature search of online archives of published manuscripts and conference proceedings. A graphical reconstructive algorithm was utilized to retrieve time-to-event data from reported Kaplan-Meier OS and PFS plots to allow for comparison of survival outcomes. Survival analyses were conducted with Cox proportional-hazards model with a shared-frailty term. Results: Three randomized phase III trials-PALOMA-2, MONALEESA-2 and MONARCH-3-comprising 1827 patients were included. Indirect pairwise comparisons of all CDK4/6-inhibitors showed no significant PFS differences (all p > 0.05). Likewise, indirect treatment comparison between ribociclib vs. palbociclib (one-stage: HR = 0.903, 95%-CI: 0.746-1.094, p = 0.297), abemaciclib vs. palbociclib (one-stage: HR = 0.843, 95%-CI: 0.690-1.030, p = 0.094) and abemaciclib vs. ribociclib (one-stage: HR = 0.933, 95%-CI: 0.753-1.157, p = 0.528) failed to demonstrate a significant OS difference. Conclusions: Findings from this indirect treatment comparison suggest no significant PFS or OS differences between CDK4/6-inhibitors in post-menopausal patients with HR+/HER2- MBC.

A real-world study of the first use of palbociclib for the treatment of advanced breast cancer within the UK National Health Service as part of the novel Ibrance® Patient Program

BACKGROUND

The Ibrance® Patient Program was established to provide access to palbociclib for UK National Health Service (NHS) patients with metastatic breast cancer (MBC), pending a funding decision.

METHODS

Non-interventional cohort study involving a retrospective medical record review of patients commenced on palbociclib between April and December 2017 at eight UK centres. Primary outcomes included clinicopathological characteristics, treatment patterns, clinical outcomes and selected adverse events.

RESULTS

Overall, 191 patients were identified, median age of 57.0 years (range 24.3-90.9); 30% were diagnosed with de novo MBC; 72% received first-line and 10% as ≥ second-line treatment. Median progression-free survival (95% CI) was 22.8 months (16.5-not reached [NR]) in first-line; NR in patients with de novo MBC; 7.8 months (6.8-NR) in ≥ second-line (median follow-up: 24 months). Median overall survival (OS) was NR in the overall cohort; OS rate (95% CI) at 24 months was 74.2% (67.1-81.9%) in first-line; 82.1% (72.6-92.8%) in patients with de novo MBC; 55.0% (37.0-81.8%) in ≥ second-line. Forty-seven per cent of patients developed grade 3-4 neutropenia; 3% febrile neutropenia.

CONCLUSION

This study supports the effectiveness of palbociclib and demonstrates the benefit to patients of early access schemes that bridge the gap between regulatory approval and NHS funding for new medicines.

CLINICAL TRIAL REGISTRATION

Clinical trial: ClinicalTrial.gov:NCT03921866.

Real-world outcomes of patients with metastatic endocrine-responsive breast cancer receiving palbociclib-based combinations

Aim: To describe treatment journey and clinical outcomes after palbociclib initiation in HR+/HER2- breast cancer patients across multiple lines. Materials & methods: Adult patients (n = 559) were identified in a population-based study between January 2018 and June 2020. Results: Median follow-up time was 41.2 months. The starting dose was 125 mg for more than 85% of patients, and a third had dose reduction. Median time on treatment was 30.5 months for palbociclib + aromatase inhibitors for patients that received first-line treatment after metastatic diagnosis, and 12.6 months for palbociclib + fulvestrant across multiple lines, and longer for patients that had a dose reduction during treatment. At 48 months, 59.3 and 27.3% of patients were still alive, respectively. Subsequent lines resulted in median time on treatment of 4.4-7.7 months in both groups. Conclusion: Time on treatment for palbociclib was comparable to data from clinical trials, and follow-up allowed us to examine subsequent treatment after initial treatment failure. Dose reduction was common in the real-world setting and did not adversely affect efficacy.

Real World Experience of Second-Line Treatment Strategies after Palbociclib and Letrozole: Overall Survival in Metastatic Hormone Receptor-Positive Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer

BACKGROUND

We analyzed real-world practice of second-line treatment in hormone receptor (HR)+ human epidermal growth factor receptor-2 (HER2)- metastatic breast cancer (MBC) following the first-line CDK4/6 inhibitor with letrozole. In addition, we evaluated the relationship between second-line treatment strategies and survival outcome.

METHODS

Using the clinical data warehouse, clinical information including MBC diagnosis, treatment and survival outcomes were collected.

RESULTS

In total, 305 patients were treated with the first-line palbociclib plus letrozole, and we evaluated 166 patients who were treated with second-line treatment. Of the 166 patients, 28.5% were treated with capecitabine (C), followed by exemestane with everolimus (EE) (27.3%) or cytotoxic chemotherapy other than capecitabine (T) (18.8%) and fulvestrant-based treatment or endocrine monotherapy (F) (12.7%). Eighteen patients (10.9%) were enrolled in clinical trials (CT). With regard to treatment strategies, and the median progression-free survival of second-line treatment in a metastatic setting (PFS2) was 7.4 months with C, 5.2 months with EE, 4.8 months with T, 3.6 months with F, and 3.6 months with CT (p = 0.066). In patients with visceral organ disease progression, C (31.3%) or T(31.3%) was the most common second-line treatment followed by EE (21.9%). Most of the 47 patients with bone metastasis alone were treated with EE (38.2%), followed by C (23.4%) and F (21.3%) (p = 0.008). The median overall survival of second-line treatment in a metastatic setting (OS2) was 42.3 months with C, 35.7 months with F, 30.7 months with EE, and 23.1 months with T. The median OS2 for those in CT was not reached (p = 0.064). ER driven BC, disease progression site and PFS2 were associated with OS and OS2 in HR+HER2- MBC (ps < 0.05).

CONCLUSIONS

We suggested the second line treatment strategy was important to improve prognosis in patients with HR+/HER2- MBC, especially given the recent standardization of first-line treatment and the many available second-line options.

CDK4/6 Inhibitors in the First-Line Treatment of Postmenopausal Women with HR+/HER2- Advanced or Metastatic Breast Cancer: An Updated Network Meta-Analysis and Cost-Effectiveness Analysis

(1) Background: This study aimed to conduct a NMA and CEA combined study to compare the effectiveness and cost-effectiveness of different CDK4/6 inhibitors (Abem, Palbo, and Ribo) plus NSAI with placebo plus NSAI in the first-line treatment of postmenopausal women with HR+/HER2- ABC from the perspective of payers in China. (2) Methods: Studies which evaluated CDK4/6 inhibitors plus NSAI for HR+/HER2- ABC were searched. A Bayesian NMA was carried out and the main outcomes were the hazard ratios (HRs) of overall survival (OS) and progression-free survival (PFS). The costs and efficacy of first-line therapies for HR+/HER2- ABC were evaluated using the Markov model. The main outcomes in the CEA were incremental cost-utility ratios (ICURs), incremental monetary benefit (INMB), and incremental net-health benefit (INHB). The robustness of the model was assessed by one-way, three-way, and probabilistic sensitivity analyses. Then, we further simulated the impact of different prices of CDK4/6 inhibitors on the results. (3) Results: Seven studies involving 5347 patients were included in the NMA. The three first-line CDK4/6 inhibitors plus NSAI groups provided significant PFS and OS superiority to NSAI alone. Abem + NSAI represented a significant statistical advantage onPFS (HR 0.74, 95% CI 0.61-0.90, p = 0.009) and indicated a trend of being the best OS benefit compared to the placebo + NSAI group (HR 0.89, 95% CI 0.72-1.08). The Abem + NSAI, Palbo + NSAI, and Ribo + NSAI groups resulted in additional costs of $12,602, $20,391, and $81,258, with additional effects of 0.38, 0.31, and 0.30 QALYs, respectively, leading to an ICUR of $33,163/QALY, $65,777/QALY, and $270,860/QALY. Additional pairwise comparisons showed that Abem + NSAI was the only cost-effective option in three CDK4/6 inhibitors plus NSAI groups at a willingness-to-pay (WTP) of $38,029/QALY. The sensitivity analyses showed that the proportion of receiving subsequent CDK4/6 inhibitors and the cost of Abem significantly influenced the results of Abem + NSAI compared with placebo + NSAI. (4) Conclusion: From the perspective of Chinese payers, Abem + NSAI was a cost-effective treatment option compared with placebo + NSAI at the WTP of $38,029/QALY, since only the ICUR of $33,163/QALY of Abem + NSAI was lower than the WTP of $38,029/QALY in China (2022). The Palbo + NSAI and Ribo + NSAI groups were not cost-effective unless drug prices were adjusted to 50% or 10% of current prices ($320.67 per cycle or $264.60 per cycle). (5) Others: We have prospectively registered the study with the PROSPERO, and the PROSPERO registration number is CRD42023399342.

Real-world treatment patterns of subsequent therapy after palbociclib in patients with advanced breast cancer in Japan

PURPOSE

The optimal treatment following endocrine therapy (ET) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) has not been established. We aimed to investigate treatment patterns and time to treatment failure (TTF) of subsequent therapy after palbociclib in a Japanese real-world setting.

METHDS

This retrospective observational study used de-identified data of patients with advanced breast cancer treated with palbociclib, using a nationwide claims database (April 2008 to June 2021). Measures included the type of subsequent therapies after palbociclib (endocrine-based therapy: ET alone, ET + CDK4/6i, and ET + mammalian target of rapamycin inhibitor [mTORi]; chemotherapy; chemotherapy + ET; and others) and their TTFs. The median TTF and 95% confidence interval (CI) were estimated using the Kaplan-Meier method.

RESULTS

Of 1170 patients treated with palbociclib, 224 and 235 received subsequent therapies after first- and second-line palbociclib treatment, respectively. Among them, 60.7% and 52.8% were treated with endocrine-based therapies as first subsequent therapy, including ET + CDK4/6i (31.2% and 29.8%, respectively). The median TTF (95% CI) of ET alone, ET + CDK4/6i, and ET + mTORi as first subsequent therapy after first-line palbociclib were 4.4 (2.8-13.7), 10.9 (6.5-15.6), and 6.1 (5.1-7.2) months, respectively. No apparent relationship between the treatment duration of prior ET + palbociclib and subsequent abemaciclib was observed.

CONCLUSION

This real-world study revealed that one-third of the patients received sequential CDK4/6i after ET + palbociclib, and treatment duration of ET + CDK4/6i following ET + palbociclib was the longest among the treatment options. Further data are awaited to determine whether ET + targeted therapy with CDK4/6i and mTORi provides acceptable treatment options following ET + palbociclib.

P-REALITY X: A Real-World Analysis of Palbociclib Plus an Aromatase Inhibitor in HR+/HER2- Metastatic Breast Cancer-A Podcast

Stringent enrollment criteria can limit the diversity of patient populations in clinical trials and, consequently, the generalizability of clinical trial data to real-world clinical practice. In this podcast, we discuss how real-world data in heterogeneous patient populations can complement clinical trial data in informing treatment decision making for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) metastatic breast cancer. Specifically, our focus is on P-REALITY X, an observational retrospective analysis that was recently published in npj Breast Cancer. P-REALITY X used real-world data from the Flatiron database to compare the effectiveness of palbociclib plus an aromatase inhibitor versus an aromatase inhibitor alone as first-line treatment for patients with HR+/HER2- metastatic breast cancer. After stabilized inverse probability treatment weighting to control for observed confounders, both overall survival and real-world progression-free survival were significantly prolonged with palbociclib plus an aromatase inhibitor versus an aromatase inhibitor alone. Furthermore, overall survival and real-world progression-free survival benefits were observed across most subgroups examined. We discuss the clinical implications of P-REALITY X data, including how these results add to data from prior randomized clinical trials and real-world studies in supporting the use of first-line palbociclib plus an aromatase inhibitor as a standard-of-care treatment for patients with HR+/HER2- metastatic breast cancer. We also provide an example of how to integrate and describe key information about the P-REALITY X study in plain language when discussing palbociclib as a therapeutic option with patients.

Long-Term Results with Everolimus in Advanced Hormone Receptor Positive Breast Cancer in a Multicenter National Real-World Observational Study

Everolimus is the first oral targeted therapy widely used in advanced HR+/HER2- breast cancer. We sought to evaluate the impact of everolimus-based therapy on overall survival in the ESME-MBC database, a national metastatic breast cancer cohort that collects retrospective data using clinical trial-like methodology including quality assessments. We compared 1693 patients having received everolimus to 5928 patients not exposed to everolimus in the same period. Overall survival was evaluated according to treatment line, and a propensity score with the inverse probability of treatment weighting method was built to adjust for differences between groups. Crude and landmark overall survival analyses were all compatible with a benefit from everolimus-based therapy. Adjusted hazard ratios for overall survival were 0.34 (95% CI: 0.16-0.72, p = 0.0054), 0.34 (95% CI: 0.22-0.52, p < 0.0001), and 0.23 (95% CI: 0.14-0.36, p < 0.0001) for patients treated with everolimus in line 1, 2, and 3 and beyond, respectively. No clinically relevant benefit on progression-free survival was observed. Causes for everolimus discontinuation were progressive disease (56.2%), adverse events (27.7%), and other miscellaneous reasons. Despite the limitations inherent to such retrospective studies, these results suggest that adding everolimus-based therapy to the therapeutic sequences in patients with advanced HR+/HER2- breast cancer may favorably affect overall survival.

Palbociclib Adherence and Persistence in Patients with Hormone Receptor Positive/Human Epidermal Growth Factor Receptor 2 Negative (HR+/HER2-) Metastatic Breast Cancer

Purpose

To assess adherence and persistence with palbociclib therapy in patients with HR+/HER2- metastatic breast cancer (mBC) in a US real-world setting.

Methods

This retrospective study evaluated palbociclib dosing, adherence, and persistence using commercial and Medicare Advantage with Part D claims data from the Optum Research Database. Adult patients with mBC who had continuous enrollment 12 months prior to mBC diagnosis and initiated first-line palbociclib with aromatase inhibitor (AI) or fulvestrant between 02/03/2015 and 12/31/2019 were included. Demographic and clinical characteristics, palbociclib dosing and dose changes, adherence (medication possession ratio [MPR]), and persistence were measured. Adjusted logistic and Cox regression models were used to examine demographic and clinical factors associated with adherence and discontinuation.

Results

Patients (n = 1066) with a mean age of 66 years were included; 76.1% received first-line palbociclib+AI and 23.9% palbociclib+fulvestrant. Most patients (85.7%) initiated palbociclib at 125 mg/day. Of the 34.0% of patients with a dose reduction, 82.6% reduced from 125 to 100 mg/day. Overall, 80.0% of patients were adherent (MPR), and 38.3% discontinued palbociclib during a mean (SD) follow-up of 16.0 (11.2) and 17.4 (13.4) months, for palbociclib+fulvestrant and palbociclib+AI, respectively. Annual income below $75,000 was significantly associated with poor adherence. Older age (age 65-74 years (hazard ratio [HR] 1.57, 95% CI, 1.06, 2.33), age ≥75 years (HR 1.61, 95% CI: 1.08, 2.41)) and bone-only metastatic disease (HR 1.37, 95% CI, 1.06, 1.76) were significantly associated with palbociclib discontinuation.

Conclusion

In this real-world study, >85% of patients started palbociclib at 125 mg/day and 1 in 3 had dose reductions during the follow-up. Patients were generally adherent and persistent with palbociclib. Older age, bone-only disease, and low-income levels were associated with early discontinuation or non-adherence. Further studies are needed to understand the associations of clinical and economic outcomes with palbociclib adherence and persistence.

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/.