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.     

The safety and efficacy of palbociclib in the treatment of metastatic breast cancer

Introduction: Palbociclib (Ibrance®) is the first-in-class CDK4/6 inhibitor which has been introduced into clinical practice for the treatment of estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC). It is an orally administered drug, which acts by selectively inhibiting cyclin-dependant kinases CDK4 and CDK6. Given together with anti-estrogens like letrozole and fulvestrant it enhances the antiproliferative effect of these drugs without compromising the favorable toxicity profile of endocrine therapy.

Areas covered: This review gives a concise overview of the current available preclinical and clinical data about pabociclib including its chemistry, mechanism of action, pharmacokinetics and evidence of its substantial anti-tumor efficacy and safety profile when combined with endocrine therapy

Expert commentary: Palbociclib doubles treatment efficacy of letrozole and fulvestrant with a restricted and well manageable toxicity profile. Efficacy as well as safety results from the three registration trials are remarkably consistent. Patients’ quality of life is maintained on palbociclib treatment. The treatment landscape in ER+ HER2? MBC will be highly influenced by this compound and development of two other CDK4/6 inhibitors.     

哌柏西利联合内分泌治疗晚期激素受体阳性乳腺癌的真实世界研究

目的评价哌柏西利联合内分泌治疗HR+/HER2−晚期乳腺癌患者的疗效及安全性。方法回顾性分析2018年9月15日至2020年10月30日本中心83例采用哌柏西利联合内分泌治疗的HR+/HER2−晚期乳腺癌患者的临床资料,评估其临床疗效、无进展生存期(PFS)及不良反应。结果共纳入的83例HR+/HER2-晚期乳腺癌患者,中位随访时间为15.5个月,一线(n=25)和二线(n=38)采用哌柏西利联合内分泌治疗患者的ORR高于多线治疗患者(n=20),但差异无统计学意义(48.0%vs 44.7%vs 30.0%,P=0.466),3组患者的疾病控制率差异也无统计学意义(96.0%vs 89.5%vs 80.0%,P=0.337)。哌柏西利联合组全人群mPFS为13.0个月(95%CI:11.4~14.6个月),一线/二线治疗患者的mPFS较多线治疗患者延长(20.0个月vs 14.0个月vs 5.0个月,P<0.001),仅有骨转移的患者mPFS优于非骨转移患者(未达到vs 13.0个月;HR=0.42,95%CI:0.22~0.84,P=0.01);无内脏转移患者的mPFS优于存在内脏转移患者,但差异无统计学意义(20.0个月vs 13.0个月;HR=0.65,95%CI:0.35~1.22,P=0.38)。依维莫司联合内分泌治疗耐药患者应用哌柏西利治疗仍可获益(mPFS=5个月)。83例患者采用哌柏西利联合治疗后常见和严重的不良反应均为中性粒细胞减少,其中12例因不良反应下调剂量。结论哌柏西利联合内分泌治疗HR+/HER2-晚期乳腺癌患者的临床疗效显著,尤其是一/二线治疗取得较好疗效,安全性良好。     

Quality of life with palbociclib plus fulvestrant in previously treated hormone receptor-positive,HER2-negative metastatic breast cancer: patient-reported outcomes from the PALOMA-3 trial

BackgroundIn the PALOMA-3 study, palbociclib plus fulvestrant demonstrated improved progression-free survival compared with fulvestrant plus placebo in hormone receptor-positive, HER2- endocrine-resistant metastatic breast cancer (MBC). This analysis compared patient-reported outcomes (PROs) between the two treatment groups.Patients and methodsPatients were randomized 2: 1 to receive palbociclib 125 mg/day orally for 3 weeks followed by 1 week off (n = 347) plus fulvestrant (500 mg i.m. per standard of care) or placebo plus fulvestrant (n = 174). PROs were assessed on day 1 of cycles 1–4 and of every other subsequent cycle starting with cycle 6 using the EORTC QLQ-C30 and its breast cancer module, QLQ-BR23. High scores (range 0–100) could indicate better functioning/quality of life (QoL) or worse symptom severity. Repeated-measures mixed-effect analyses were carried out to compare on-treatment overall scores and changes from baseline between treatment groups while controlling for baseline. Between-group comparisons of time to deterioration in global QoL and pain were made using an unstratified log-rank test and Cox proportional hazards model.ResultsQuestionnaire completion rates were high at baseline and during treatment (from baseline to cycle 14, ≥95.8% in each group completed ≥1 question on the EORTC QLQ-C30). On treatment, estimated overall global QoL scores significantly favored the palbociclib plus fulvestrant group [66.1, 95% confidence interval (CI) 64.5–67.7 versus 63.0, 95% CI 60.6–65.3; P = 0.0313]. Significantly greater improvement from baseline in pain was also observed in this group (-3.3, 95% CI -5.1 to -1.5 versus 2.0, 95% CI -0.6 to 4.6; P = 0.0011). No significant differences were observed for other QLQ-BR23 functioning domains, breast or arm symptoms. Treatment with palbociclib plus fulvestrant significantly delayed deterioration in global QoL (P < 0.025) and pain (P < 0.001) compared with fulvestrant alone.ConclusionPalbociclib plus fulvestrant allowed patients to maintain good QoL in the endocrine resistance setting while experiencing substantially delayed disease progression.Clinical Trial RegistrationNCT01942135.     

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

BackgroundPalbociclib, 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.MethodsWe 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.Results8 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.ConclusionsPalbociclib, 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.     

Clinical considerations of the role of palbociclib in the management of advanced breast cancer patients with and without visceral metastases

BackgroundThis report assesses the efficacy and safety of palbociclib plus endocrine therapy (ET) in women with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced breast cancer (ABC) with or without visceral metastases.Patients and methodsPre- and postmenopausal women with disease progression following prior ET (PALOMA-3; N = 521) and postmenopausal women untreated for ABC (PALOMA-2; N = 666) were randomized 2 : 1 to ET (fulvestrant or letrozole, respectively) plus palbociclib or placebo. Progression-free survival (PFS), safety, and patient-reported quality of life (QoL) were evaluated by prior treatment and visceral involvement.ResultsVisceral metastases incidence was higher in patients with prior resistance to ET (58.3%, PALOMA-3) than in patients naive to ET in the ABC setting (48.6%, PALOMA-2). In patients with prior resistance to ET and visceral metastases, median PFS (mPFS) was 9.2 months with palbociclib plus fulvestrant versus 3.4 months with placebo plus fulvestrant [hazard ratio (HR), 0.47; 95% confidence interval (CI), 0.35–0.61], and objective response rate (ORR) was 28.0% versus 6.7%, respectively. In patients with nonvisceral metastases, mPFS was 16.6 versus 7.3 months, HR 0.53; 95% CI 0.36–0.77. In patients with visceral disease and naive to ET in the advanced disease setting, mPFS was 19.3 months with palbociclib plus letrozole versus 12.9 months with placebo plus letrozole (HR 0.63; 95% CI 0.47–0.85); ORR was 55.1% versus 40.0%; in patients with nonvisceral disease, mPFS was not reached with palbociclib plus letrozole versus 16.8 months with placebo plus letrozole (HR 0.50; 95% CI 0.36–0.70). In patients with prior resistance to ET with visceral metastases, palbociclib plus fulvestrant significantly delayed deterioration of QoL versus placebo plus fulvestrant, whereas patient-reported QoL was maintained with palbociclib plus letrozole in patients naive to endocrine-based therapy for ABC.ConclusionsPalbociclib plus ET prolonged mPFS in patients with visceral metastases, increased ORRs, and in patients previously treated for ABC, delayed QoL deterioration, presenting a standard treatment option among patients with visceral metastases amenable to endocrine-based therapy.Clinical trial registrationNCT01942135, NCT01740427     

Preclinical and clinical development of palbociclib and future perspectives

Cyclin-dependent kinases (CDKs) play a key role in cell cycle regulation, which makes them a clear therapeutic target to interfere with cell division and proliferation in cancer patients. Palbociclib, a specific inhibitor of CDK4/6 with outstanding clinical efficacy data and limited toxicity, has been recently approved for the treatment of hormone receptor (HR)-positive human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer, either in combination with an aromatase inhibitor or in combination with fulvestrant in women who have received prior endocrine therapy. This review describes the mechanism of action, preclinical experiences and clinical data of palbociclib, with a special focus on integrating this data with the positioning of palbociclib in the current clinical guidelines for advanced HR-positive/HER2-negative breast cancer. Aspects of the ongoing major studies are also presented, as well as future prospects in the development of palbociclib.     

Prognostic Factors for Overall Survival in Patients with Hormone Receptor-Positive Advanced Breast Cancer: Analyses From PALOMA-3

Background

This analysis investigated whether baseline characteristics affect the survival benefit derived from palbociclib-fulvestrant and the optimal timing of cyclin-dependent kinase 4/6 inhibitor therapy for advanced breast cancer (ABC) in patients from PALOMA-3.

Patients and Methods

In total, 521 patients were randomized 2:1 to receive palbociclib (125 mg/day, 3/1 schedule)–fulvestrant (500 mg, intramuscular injection, on days 1 and 15 of cycle 1, and then day 1 of each subsequent cycle) or matching placebo-fulvestrant. Median overall survival (OS) and progression-free survival were estimated using the Kaplan-Meier method.

Results

Multivariable analysis identified endocrine sensitivity, nonvisceral disease, no prior chemotherapy for ABC, and Eastern Cooperative Oncology Group performance status (ECOG PS) of 0 as significant prognostic factors for OS. Patients without chemotherapy for ABC had fewer prior lines of treatment in any setting and in the ABC setting versus patients with prior chemotherapy for ABC (two or fewer prior systemic therapies: 69% vs. 42%; no more than one prior line for ABC: 82% vs. 33%, respectively). Median OS was prolonged with palbociclib-fulvestrant in patients without prior chemotherapy for ABC (39.7 vs. 29.5 months; hazard ratio, 0.75; 95% confidence interval [CI]: 0.56–1.01) and was similar in patients with prior chemotherapy for ABC (25.6 vs. 26.2 months; hazard ratio, 0.91 [95% CI: 0.63–1.32]) versus placebo-fulvestrant.

Conclusion

Prognostic factors for OS included endocrine sensitivity, nonvisceral disease, ECOG PS of 0, and no prior chemotherapy for ABC. Exploratory analyses suggest improved OS with palbociclib-fulvestrant versus placebo-fulvestrant in patients with no prior chemotherapy for ABC, prior endocrine sensitivity, and fewer prior regimens of systemic therapy. (Clinical trial identification number: NCT01942135).

Implications for Practice

Prognostic factors for overall survival in HR+/HER2− advanced breast cancer (ABC) include the absence of prior chemotherapy in the advanced setting, endocrine sensitivity, nonvisceral disease, and an ECOG performance status of 0. Improved overall survival benefit was observed with palbociclib-fulvestrant versus placebo-fulvestrant in patients (regardless of menopausal status or visceral involvement) with no prior chemotherapy for ABC, with prior endocrine sensitivity, and fewer prior regimens of systemic therapy. Progression-free survival was prolonged with palbociclib across subgroups (regardless of chemotherapy exposure in ABC). These exploratory findings suggest that patients may receive greater clinical benefit from palbociclib-fulvestrant if they receive the combination before chemotherapy in the advanced setting.

     

Fulvestrant ('Faslodex') in pre-treated patients with advanced breast cancer: a single-centre experience

Fulvestrant ('Faslodex') is a new oestrogen receptor (ER) antagonist with no agonist effects. This report describes the experience of a single centre including 126 postmenopausal women with advanced breast cancer (ABC) in a fulvestrant Compassionate Use Programme. All patients had previously received endocrine treatment for early or ABC. Patients received fulvestrant as first- (n=7), second- (n=51), third- (n=50) or fourth-line endocrine therapy (n=18) for ABC (median duration of treatment: 4 months [range 3-27(+) months], follow-up: 13 months [range 1-38(+) months]). Twelve patients had partial responses (PR) and 43 patients experienced stable disease (SD) > or = 6 months (objective response rate: 9.5%; clinical benefit [CB] rate: 43.6%). Ten of 12 patients with a PR had HER2-negative tumours, and 9/12 had ER-positive and progesterone receptor (PgR)-positive disease (two patients had unknown HER2 status and one had unknown ER and PgR status). Nine of the 18 patients with HER2-positive tumours experienced CB with fulvestrant. Although CB rates were similar when fulvestrant was given as first- to fourth-line endocrine treatment, the proportion of those experiencing CB who had a PR appeared to decrease when fulvestrant was used later in the sequence. Fulvestrant was well tolerated; six patients experienced adverse events (all grade I/II). These data demonstrate that fulvestrant is an effective and well-tolerated therapy for patients with ABC progressing on prior therapies.     

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

BackgroundAdditional use of cyclin-dependent kinase 4/6 inhibitors with endocrine therapy improves progression-free survival (PFS) in advanced hormone receptor (HR)-positive HER2-negative breast cancer. However, neutropenia is a common reason for dose reductions, leading to concerns about palbociclib efficacy at lower doses. A safety analysis confirmed no PFS differences between palbociclib doses in the second-line setting, but to our knowledge, this has not been evaluated for first-line treatment.Patients and MethodsIn this retrospective, single-center cohort study we evaluated real-world use of first-line palbociclib with aromatase inhibitor (AI) treatment in HR-positive, HER2-negative metastatic breast cancer patients who received treatment between February 2015 and July 2017. The primary objective was to determine PFS of treatment with palbociclib and an AI in a real-world first-line setting. Secondary objectives included determining the PFS for patients treated with palbociclib on the basis of final doses, time to first dose reduction, time to treatment failure (TTF), and safety.ResultsSeventy patients were included in the final analysis. Median PFS was 26.4 months. No significant differences in PFS were observed on the basis of final doses of palbociclib (P = .77). Time to first dose reduction was 2.3 months. Median TTF was 26.1 months. Dose delays, reductions, and Grade 3/4 neutropenia were common (63%, n = 44; 57%, n = 40; and 62%, n = 43, respectively).ConclusionReal-world first-line palbociclib treatment produced outcomes similar to those in PALOMA-2 (Palbociclib and Letrozole in Advanced Breast Cancer) (median PFS 26.4 months vs. 24.8 months) despite more dose reductions (57%, n = 40 vs. 36%, n = 160) and shorter time to first dose reduction (2.3 vs. 3.0 months). No significant differences in PFS were observed for the varying palbociclib doses. Palbociclib dose reductions might not significantly affect PFS in the first-line setting.     

A randomized trial to assess the biological activity of short-term (pre-surgical) fulvestrant 500 mg plus anastrozole versus fulvestrant 500 mg alone or anastrozole alone on primary breast cancer

Introduction

Fulvestrant shows dose-dependent biological activity. Greater estrogen-receptor (ER) blockade may feasibly be achieved by combining fulvestrant with anastrozole. This pre-surgical study compared fulvestrant plus anastrozole versus either agent alone in patients with ER-positive breast cancer.

Methods

In this double-blind, multicenter trial, 121 patients received fulvestrant 500 mg on Day 1 plus anastrozole 1 mg/day for 14 to 21 days (F + A); fulvestrant plus anastrozole placebo (F); or fulvestrant placebo plus anastrozole (A), 2 to 3 weeks before surgery. ER, progesterone-receptor (PgR) and Ki67 expression were determined from tumor biopsies before treatment and at surgery.

Results

A total of 103 paired samples were available (F, n = 35; F+A, n = 31; A, n = 37). All treatments significantly reduced mean ER expression from baseline (F: -41%, P = 0.0001; F + A: -39%, P = 0.0001; A: -13%, P = 0.0034). F and F + A led to greater reductions in ER versus A (both P = 0.0001); F + A did not lead to additional reductions versus F. PgR and Ki67 expression were significantly reduced with all treatments (means were -34% to -45%, and -75% to -85%, respectively; all P = 0.0001), with no differences between groups.

Conclusions

In this short-term study, all treatments reduced ER expression, although F and F + A showed greater reductions than A. No significant differences were detected between the treatment groups in terms of PgR and Ki67 expression. No additional reduction in tumor biomarkers with combination treatment was observed, suggesting that F + A is unlikely to have further clinical benefit over F alone.

Trial registration

Clinicaltrials.gov NCT00259090.     

Real-World Treatment Patterns and Outcomes of Palbociclib Plus an Aromatase Inhibitor for Metastatic Breast Cancer: Flatiron Database Analysis

IntroductionTo describe real-world treatment patterns and effectiveness of first-line palbociclib plus an aromatase inhibitor (PAL+AI) and examine the association between PAL initial dose and effectiveness among patients with hormone receptor–positive/human epidermal growth factor receptor 2–negative metastatic/advanced breast cancer (HR+/HER2– MBC) in routine clinical practice.Patients and MethodsThis retrospective analysis used Flatiron Health's database of electronic health records from >280 cancer clinics representing >2.4 million actively treated cancer patients in the United States. Women with HR+/HER2− MBC who received first-line PAL+AI were included. Real-world progression-free survival (rwPFS) was defined as the time from starting PAL+AI to death or disease progression. Real-world best tumor response (rwBTR) was assessed based on the treating clinician's assessment of radiologic evidence for change in disease burden.ResultsOf 813 eligible patients, median age was 65.0 years, and median follow-up was 21.0 months. PAL was initiated at 125 mg/d and 75/100 mg/d in 86.5% and 13.5% of patients, respectively. Median duration of PAL+AI was 16.3 months. 43.0% of patients discontinued PAL+ AI; 11.0% discontinued because of toxicity. Median time to subsequent therapy and chemotherapy was 24.6 and 36.6 months, respectively. Median rwPFS was 20.0 months, and best rwBTR rate was 51.9%. Patients starting PAL at 125 versus 75/100 mg/d had longer median rwPFS (27.8 vs. 18.6 months) and higher rwBTR rate (54.0% vs. 40.4%).ConclusionThese data demonstrate the benefit of PAL+AI in routine clinical practice and may support the initiation of palbociclib at the recommended dose of 125 mg/d for HR+/HER2− MBC.Trial Registration Number and Date of RegistrationNCT04176354, November 25, 2019     

Efficacy of Palbociclib Combinations in Hormone Receptor–Positive Metastatic Breast Cancer Patients After Prior Everolimus Treatment

Purpose

Outcome data on hormone receptor positive (HR⁺), human epidermal growth factor receptor 2 (HER2) nonamplified (HER2^?) metastatic breast cancer (MBC) treated with palbociclib after treatment with everolimus are lacking. The PALOMA-3 trial, showing benefit of palbociclib plus fulvestrant compared to fulvestrant alone in HR⁺HER2^? MBC after progression while receiving endocrine therapy excluded women previously treated with everolimus. The objective of this study was to examine outcomes of HR⁺HER2^? MBC with prior exposure to everolimus while receiving palbociclib-based therapy.

Progression-free Survival Outcome Is Independent of Objective Response in Patients With Estrogen Receptor-positive,Human Epidermal Growth Factor Receptor 2-negative Advanced Breast Cancer Treated With Palbociclib Plus Letrozole Compared With Letrozole: Analysis From PALOMA-2

BackgroundIn PALOMA-2, palbociclib + letrozole significantly prolonged progression-free survival (PFS) versus placebo + letrozole in patients with estrogen receptor-positive/human epidermal growth factor receptor 2-negative (ER⁺/HER2⁻) advanced breast cancer (ABC). We investigated clinical outcomes of patients who achieved or did not achieve a confirmed objective response (OR) according to Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 (data cutoff: May 31, 2017).Patients and MethodsPostmenopausal patients untreated for ER⁺/HER2⁻ ABC were randomized 2:1 to palbociclib + letrozole or placebo + letrozole. Median PFS, median duration of OR, baseline characteristics, and palbociclib exposure were compared in patients with or without OR by treatment arm.ResultsIn the intent-to-treat population, OR was achieved by 194 (44%) of 444 and 77 (35%) of 222 patients in the palbociclib and placebo arms, respectively (odds ratio, 1.5; 95% confidence interval [CI], 1.0-2.1; P = .0156). Regardless of treatment, more OR than non-OR patients had de novo metastatic disease (47%-50% and 28%-31%, respectively) and no prior endocrine therapy (55% and 35%-37%, respectively). Rates of palbociclib dose reduction owing to adverse events were similar regardless of OR (41% and 38%, respectively). Among the patients with OR during the study, approximately 50% achieved OR within the first 3 months regardless of treatment. The median PFS was significantly prolonged with palbociclib + letrozole versus placebo + letrozole in patients with measurable disease in both OR (37.2 months; 95% CI, 28.1 months to not estimable vs. 27.4 months; 95% CI, 22.2-31.1 months; hazard ratio, 0.66; 95% CI, 0.47-0.94; P = .009) and non-OR groups (10.9 months; 95% CI, 8.2-11.2 months vs. 5.6 months; 95% CI, 5.3-8.3 months; hazard ratio, 0.72; 95% CI, 0.54-0.97; P = .016).ConclusionsPalbociclib + letrozole provided significant clinical benefit versus placebo + letrozole to patients with ER⁺/HER2⁻ ABC regardless of achieving RECIST-defined OR.Pfizer; ClinicalTrials.gov: NCT01740427     

Quality-Adjusted Survival with Ribociclib Plus Fulvestrant Versus Placebo Plus Fulvestrant in Postmenopausal Women with HR±HER2− Advanced Breast Cancer in the MONALEESA-3 Trial

BackgroundMONALEESA-3 demonstrated an overall survival (OS) benefit for ribociclib plus fulvestrant (R+F) in postmenopausal women with hormone receptor (HR) positive, HER2 negative advanced breast cancer (ABC). This study estimated quality-adjusted (QA) survival outcomes for patients receiving R+F vs. placebo (P)+F in MONALEESA-3.MethodsKaplan-Meier OS was partitioned into health states: (1) toxicity (TOX)=time spent with grade 3 –4 adverse events before progression (DP); (2) progression (PROG)=time between DP and death; and (3) time without symptoms or toxicity (TWiST)=time not in TOX or PROG. QA time was calculated by combining estimated mean time in each health state with treatment-group specific health-state utility values estimated using EQ-5D-5L questionnaire. Outcomes included QA progression-free survival (QAPFS), QAOS, and QA TWiST (Q-TWiST). Q-TWiST was calculated with health-state utility values for TOX and PROG defined relative to TWiST.ResultsMean PFS and OS were significantly greater with R+F vs. P+F (difference 0.56 and 0.19 years). Mean time in TOX and TWiST were greater with R+F; mean time in PROG was greater with P+F. QAPFS was 0.45 years (95% CI 0.27 –0.63) greater with R+F than P+F (P <.001). QAOS was numerically greater with R+F vs. P+F (0.16 years, 95% CI 0.07 –0.45, P = .0569). Q-TWiST was 0.23 years greater with R+F (95% CI 0.07 –0.45, P = .0069). In a sensitivity analysis using an estimate of disutility for PROG, the difference in QAOS was 0.23 years (95% CI 0.08 –0.41, P = .0022).ConclusionR+F in postmenopausal women with HR+/HER2- ABC improves QAPFS, resulting in clinically important improvements in Q-TWiST and may improve QAOS.     

Real-world Outcomes of Cyclin-dependent Kinase Inhibitors Continued Beyond First Disease Progression in Hormone Receptor-positive Metastatic Breast Cancer

BackgroundCDK4/6 inhibitors (CDK4/6i), in combination with aromatase inhibitors, are United States Food and Drug Administration-approved for the treatment of hormone receptor-positive (HR⁺)/human epidermal growth factor receptor 2-negative (HER2^?) metastatic breast cancer (MBC). The effectiveness of continuing them beyond first disease progression (PD) is currently unknown. This retrospective study evaluated the impact of the continuation of CDK4/6i beyond first PD in HR⁺/HER2^? MBC using real-world experience.Patients and MethodsA single-institution retrospective review of patients with HR⁺ MBC who received CDK4/6is from 2015 to 2018 and where CDK4/6is were continued beyond first PD. The primary outcome was progression-free survival (PFS) after initial PD on CDK4/6i therapy.ResultsThirty women with HR⁺/HER2^? MBC met eligibility criteria. Patients were identified from a prospective database of patients at the Cleveland Clinic Foundation who were prescribed CDK4/6is. The median age and follow-up duration were 47.5 years and 27 months, respectively. Most patients received palbociclib (PA)/letrozole as initial therapy (67%), followed by PA/fulvestrant (23%), and PA/other aromatase inhibitor (20%), and abemaciclib with either fulvestrant or letrozole (6%). As of January 31, 2019, 25 (83.3%) patients were still alive, and 19 (63%) patients had progressed. The estimated median PFS for continued CDK4/6i use beyond the first PD was 11.8 months (95% confidence interval, 5.34-13.13 months).ConclusionsAmong a small cohort of patients with HR⁺ MBC in a non-clinical trial setting, continuation of CDK4/6i-endocrine treatment post initial PD was associated with a median PFS of about 12 months. Formal randomized clinical trials evaluating the continuation of CDK4/6is beyond the first PD are currently ongoing and will provide more answers to this important clinical question.     

Palbociclib in highly pretreated metastatic ER-positive HER2-negative breast cancer

Purpose

We aimed to investigate the role of palbociclib, a first-in-class cyclin-dependent kinase 4 and 6 inhibitor, in postmenopausal women with highly pretreated endocrine therapy-resistant metastatic breast cancer (MBC).

Methods

Between 28 September 2015 and 14 March 2017, a compassionate use program was established in the University Hospitals Leuven in which 82 postmenopausal women with estrogen receptor-positive, HER2-negative MBC were included after at least four lines of systemic treatment. The efficacy and safety analysis was performed in 82 patients who had received at least one dose of palbociclib and who had at least 6-month follow-up at the data cut-off point. The primary objective was the evaluation of efficacy of the combination of palbociclib and endocrine therapy with clinical benefit as primary endpoint, defined as the absence of progressive disease and being on treatment for at least 6 months. Secondary objectives were the evaluation of toxicity and the identification of potential predictors for clinical benefit.

Results

The median age of the patients was 67.1 years (range 34.8–85.9) at the time of inclusion. The average duration of treatment was 5.6 months (range 1–19), with a median progression-free survival of 3.17 (95% CI 2.76–4.70) months. At the data cut-off point, 10 patients were still on treatment with palbociclib. In this highly pretreated setting, 34 patients experienced no progressive disease within 6 months, resulting in an overall clinical benefit rate (CBR) of 41.5%. 20.7% (17/82) showed stable disease for ≥?9 months and 13.4% for ≥?12 months. None of the investigated predicting factors were significantly associated with clinical benefit at 6 months. For 43.9% of the patients, treatment delay or dose reduction was indicated.

Conclusions

Palbociclib in combination with endocrine therapy shows an unexpectedly high CBR and favorable safety profile in heavily pretreated endocrine-resistant estrogen receptor-positive, HER2-negative MBC patients.

     

Palbociclib as single agent or in combination with the endocrine therapy received before disease progression for estrogen receptor-positive,HER2-negative metastatic breast cancer: TREnd trial

BackgroundThe activity of palbociclib as a single agent in advanced breast cancer has not been extensively studied, with the only available clinical data limited to heavily pretreated patients. Preclinical data suggests palbociclib may partially reverse endocrine resistance, though this hypothesis has not been evaluated in previous clinical studies. This phase II, open-label, multicenter study examined the activity of palbociclib monotherapy, as well as palbociclib given in combination with the same endocrine therapy (ET) that was received prior to disease progression, in postmenopausal women with moderately pretreated, estrogen receptor-positive, HER2 negative advanced breast cancer.Patients and methodsEligible women with advanced disease which had progressed on one or two prior ETs were randomized 1 : 1 to receive either palbociclib alone, or palbociclib in combination with the ET as previously received. Primary end point was clinical benefit rate (CBR); secondary end points included progression-free survival (PFS).ResultsBetween October 2012 and July 2016, a total of 115 patients were randomized. The CBR was 54% [95% confidence interval (CI): 41.5–63.7] for combination therapy, and 60% (95% CI: 47.8–72.9) for monotherapy. Median PFS was 10.8 months (95% CI: 5.6–12.7) for combination therapy, and 6.5 months (95% CI: 5.4–8.5) for monotherapy [hazard ratio (HR) 0.69; 95% CI: 0.4–1.1, exploratory P-value = 0.12]. Exploratory analyses revealed the PFS advantage for combination therapy was seen in the subgroup of patients who received prior ET for >6 months (HR 0.53; 95% CI: 0.3–0.9, exploratory P-value = 0.02), but not in those who received prior ET for ≤6 months.ConclusionPalbociclib has clinical activity as a single agent in women with moderately pretreated, oestrogen receptor-positive, HER2-negative advanced breast cancer. Palbociclib may have potential to reverse endocrine resistance in patients with a history of previous durable response to ET.Clinical trial informationNCT02549430     

Palbociclib plus letrozole as first-line treatment for ER-positive and HER2-negative advanced breast cancer in Chinese women: a phase 1 study

BackgroundPalbociclib, a cyclin-dependent kinase 4 and 6 inhibitor, is approved in many countries for the treatment of ER-positive and HER2-negative advanced breast cancer in combination with endocrine therapy. We aimed to evaluate the pharmacokinetics, safety, and efficacy of palbociclib combined with letrozole as first-line treatment for ER-positive and HER2-negative advanced breast cancer.MethodsThis is a phase 1, open-label, single-arm study in Chinese women with ER-positive and HER2-negative advanced breast cancer. From cycle 1 day 1, patients received letrozole 2·5 mg orally once daily continuously plus palbociclib 125 mg orally once daily for 3 weeks followed by 1 week off treatment. Blood samples for pharmacokinetic evaluation of palbociclib were collected up to 120 h after a single dose of palbociclib in a lead-in phase and after palbociclib dose on cycle 1 day 21 for multiple dose pharmacokinetic evaluation. Predose blood samples for pharmacokinetic evaluation of palbociclib and letrozole were collected on days 19–21 of cycle 1 and cycle 2 day 1 (letrozole only). Disease assessments were done every 12 weeks from cycle 1 day 1. Safety was assessed per Common Terminology Criteria for Adverse Events, version 4.0. This study is registered with ClinicalTrials, number NCT02499146, and is ongoing but not recruiting.FindingsAs of March 16, 2016, the cutoff date, the study completed enrolment with 26 patients. All patients completed single dose pharmacokinetic evaluation and 13 completed multiple dose pharmacokinetic evaluation. After multiple doses, the steady-state palbociclib geometric mean area under the concentration–time curve from 0 to 24 h was 2005 ng × h/mL and maximum observed concentration was 112·3 ng/mL, similar to those obtained in Caucasian patients following the same dosing regimen. Comparisons of single dose and multiple dose pharmacokinetic data indicated linear pharmacokinetics of palbociclib. The geometric mean accumulation ratio of palbociclib exposure after multiple dose compared with single dose was 2·1, consistent with a terminal half-life of 23·4–27·5 h. Trough concentrations of letrozole were similar to concentrations obtained in Caucasian patients. No deaths or permanent discontinuations due to adverse events were reported. One serious adverse event occurred but was not considered to be treatment-related. The most common clustered adverse events were neutropaenia (n=20, 77%), leukopaenia (n=19, 73%), and anemia (n=11, 42%), with neutropaenia (n=15, 58%) and leukopaenia (n=8, 31%) the most common grade 3–4 adverse events.InterpretationNo dose adjustment for palbociclib is needed based on the Chinese population. The toxicity of palbociclib in combination with letrozole treatment was tolerable and manageable.FundingPfizer Inc.     

A phase II feasibility study of palbociclib in combination with adjuvant endocrine therapy for hormone receptor-positive invasive breast carcinoma

BackgroundThe CDK4/6 inhibitor palbociclib prolongs progression-free survival in hormone receptor-positive/HER2-negative (HR+/HER2−) metastatic breast cancer when combined with endocrine therapy. This phase II trial was designed to determine the feasibility of adjuvant palbociclib and endocrine therapy for early breast cancer.Patients and methodsEligible patients with HR+/HER2− stage II–III breast cancer received 2 years of palbociclib at 125 mg daily, 3 weeks on/1 week off, with endocrine therapy. The primary end point was discontinuation from palbociclib due to toxicity, non-adherence, or events related to tolerability. A discontinuation rate of 48% or higher would indicate the treatment duration of 2 years was not feasible, and was evaluated under a binomial test using a one-sided α = 0.025.ResultsOverall, 162 patients initiated palbociclib; over half had stage III disease (52%) and most received prior chemotherapy (80%). A total of 102 patients (63%) completed 2 years of palbociclib; 50 patients discontinued early for protocol-related reasons (31%, 95% CI 24% to 39%, P = 0.001), and 10 discontinued due to protocol-unrelated reasons. The cumulative incidence of protocol-related discontinuation was 21% (95% CI 14% to 27%) at 12 months from start of treatment. Rates of palbociclib-related toxicity were congruent with the metastatic experience, and there were no cases of febrile neutropenia. Ninety-one patients (56%) required at least one dose reduction.ConclusionAdjuvant palbociclib is feasible in early breast cancer, with a high proportion of patients able to complete 2 years of therapy. The safety profile in the adjuvant setting mirrors that observed in metastatic disease, with approximately half of the patients requiring dose-modification. As extended duration adjuvant palbociclib appears feasible and tolerable for most patients, randomized phase III trials are evaluating clinical benefit in this population.Clinicaltrials.gov registrationNCT02040857.