Palbociclib Combined with Fulvestrant in Premenopausal Women with Advanced Breast Cancer and Prior Progression on Endocrine Therapy: PALOMA-3 Results.
The efficacy and safety of palbociclib, a cyclin-dependent kinase 4/6 inhibitor, combined with fulvestrant and goserelin was assessed in premenopausal women with advanced breast cancer (ABC) who had progressed on prior endocrine therapy (ET).
One hundred eight premenopausal endocrine-refractory women ≥18 years with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) ABC were among 521 women randomized 2:1 (347:174) to fulvestrant (500 mg) ± goserelin with either palbociclib (125 mg/day orally, 3 weeks on, 1 week off) or placebo. This analysis assessed whether the overall tolerable safety profile and significant progression-free survival (PFS) improvement extended to premenopausal women. Potential drug-drug interactions (DDIs) and ovarian suppression with goserelin were assessed via plasma pharmacokinetics and biochemical analyses, respectively. (ClinicalTrials.gov identifier: NCT01942135) RESULTS: Median PFS for premenopausal women in the palbociclib (n = 72) versus placebo arm (n = 36) was 9.5 versus 5.6 months, respectively (hazard ratio, 0.50, 95% confidence interval: 0.29-0.87), and consistent with the significant PFS improvement in the same arms for postmenopausal women. Any-grade and grade ≤3 neutropenia, leukopenia, and infections were among the most frequent adverse events reported in the palbociclib arm with concurrent goserelin administration. Hormone concentrations were similar between treatment arms and confirmed sustained ovarian suppression. Clinically relevant DDIs were not observed.
Palbociclib combined with fulvestrant and goserelin was an effective and well-tolerated treatment for premenopausal women with prior endocrine-resistant HR+/HER2- ABC. Inclusion of both premenopausal and postmenopausal women in pivotal combination ET trials facilitates access to novel drugs for young women and should be considered as a new standard for clinical trial design.
PALOMA-3, the first registrational study to include premenopausal women in a trial investigating a CDK4/6 inhibitor combined with endocrine therapy, has the largest premenopausal cohort reported in an endocrine-resistant setting. In pretreated premenopausal women with hormone receptor-positive advanced breast cancer, palbociclib plus fulvestrant and goserelin (luteinizing hormone-releasing hormone [LHRH] agonist) treatment almost doubled median progression-free survival (PFS) and significantly increased the objective response rate versus endocrine monotherapy, achieving results comparable to those reported for chemotherapy without apparently interfering with LHRH agonist-induced ovarian suppression. The significant PFS gain and tolerable safety profile strongly support use of this regimen in premenopausal women with endocrine-resistant disease who could possibly delay chemotherapy.
Loibl S
，Turner NC
，Ro J
，Cristofanilli M
，Iwata H
，Im SA
，Masuda N
，Loi S
，André F
，Harbeck N
，Verma S
，Folkerd E
，Puyana Theall K
，Hoffman J
，Zhang K
，Bartlett CH
，Dowsett M
... -
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The cyclin-dependent kinase 4/6 inhibitor palbociclib in combination with letrozole versus letrozole alone as first-line treatment of oestrogen receptor-positive, HER2-negative, advanced breast cancer (PALOMA-1/TRIO-18): a randomised phase 2 study.
Palbociclib (PD-0332991) is an oral, small-molecule inhibitor of cyclin-dependent kinases (CDKs) 4 and 6 with preclinical evidence of growth-inhibitory activity in oestrogen receptor-positive breast cancer cells and synergy with anti-oestrogens. We aimed to assess the safety and efficacy of palbociclib in combination with letrozole as first-line treatment of patients with advanced, oestrogen receptor-positive, HER2-negative breast cancer.
In this open-label, randomised phase 2 study, postmenopausal women with advanced oestrogen receptor-positive and HER2-negative breast cancer who had not received any systemic treatment for their advanced disease were eligible to participate. Patients were enrolled in two separate cohorts that accrued sequentially: in cohort 1, patients were enrolled on the basis of their oestrogen receptor-positive and HER2-negative biomarker status alone, whereas in cohort 2 they were also required to have cancers with amplification of cyclin D1 (CCND1), loss of p16 (INK4A or CDKN2A), or both. In both cohorts, patients were randomly assigned 1:1 via an interactive web-based randomisation system, stratified by disease site and disease-free interval, to receive continuous oral letrozole 2.5 mg daily or continuous oral letrozole 2.5 mg daily plus oral palbociclib 125 mg, given once daily for 3 weeks followed by 1 week off over 28-day cycles. The primary endpoint was investigator-assessed progression-free survival in the intention-to-treat population. Accrual to cohort 2 was stopped after an unplanned interim analysis of cohort 1 and the statistical analysis plan for the primary endpoint was amended to a combined analysis of cohorts 1 and 2 (instead of cohort 2 alone). The study is ongoing but closed to accrual; these are the results of the final analysis of progression-free survival. The study is registered with the ClinicalTrials.gov, number NCT00721409.
Between Dec 22, 2009, and May 12, 2012, we randomly assigned 165 patients, 84 to palbociclib plus letrozole and 81 to letrozole alone. At the time of the final analysis for progression-free survival (median follow-up 29.6 months [95% CI 27.9-36.0] for the palbociclib plus letrozole group and 27.9 months [25.5-31.1] for the letrozole group), 41 progression-free survival events had occurred in the palbociclib plus letrozole group and 59 in the letrozole group. Median progression-free survival was 10.2 months (95% CI 5.7-12.6) for the letrozole group and 20.2 months (13.8-27.5) for the palbociclib plus letrozole group (HR 0.488, 95% CI 0.319-0.748; one-sided p=0.0004). In cohort 1 (n=66), median progression-free survival was 5.7 months (2.6-10.5) for the letrozole group and 26.1 months (11.2-not estimable) for the palbociclib plus letrozole group (HR 0.299, 0.156-0.572; one-sided p<0.0001); in cohort 2 (n=99), median progression-free survival was 11.1 months (7.1-16.4) for the letrozole group and 18.1 months (13.1-27.5) for the palbociclib plus letrozole group (HR 0.508, 0.303-0.853; one-sided p=0.0046). Grade 3-4 neutropenia was reported in 45 (54%) of 83 patients in the palbociclib plus letrozole group versus one (1%) of 77 patients in the letrozole group, leucopenia in 16 (19%) versus none, and fatigue in four (4%) versus one (1%). Serious adverse events that occurred in more than one patient in the palbociclib plus letrozole group were pulmonary embolism (three [4%] patients), back pain (two [2%]), and diarrhoea (two [2%]). No cases of febrile neutropenia or neutropenia-related infections were reported during the study. 11 (13%) patients in the palbociclib plus letrozole group and two (2%) in the letrozole group discontinued the study because of adverse events.
The addition of palbociclib to letrozole in this phase 2 study significantly improved progression-free survival in women with advanced oestrogen receptor-positive and HER2-negative breast cancer. A phase 3 trial is currently underway.
Pfizer.
Finn RS
，Crown JP
，Lang I
，Boer K
，Bondarenko IM
，Kulyk SO
，Ettl J
，Patel R
，Pinter T
，Schmidt M
，Shparyk Y
，Thummala AR
，Voytko NL
，Fowst C
，Huang X
，Kim ST
，Randolph S
，Slamon DJ
... -
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Fulvestrant plus palbociclib versus fulvestrant plus placebo for treatment of hormone-receptor-positive, HER2-negative metastatic breast cancer that progressed on previous endocrine therapy (PALOMA-3): final analysis of the multicentre, double-blind, phas
In the PALOMA-3 study, the combination of the CDK4 and CDK6 inhibitor palbociclib and fulvestrant was associated with significant improvements in progression-free survival compared with fulvestrant plus placebo in patients with metastatic breast cancer. Identification of patients most suitable for the addition of palbociclib to endocrine therapy after tumour recurrence is crucial for treatment optimisation in metastatic breast cancer. We aimed to confirm our earlier findings with this extended follow-up and show our results for subgroup and biomarker analyses.
In this multicentre, double-blind, randomised phase 3 study, women aged 18 years or older with hormone-receptor-positive, HER2-negative metastatic breast cancer that had progressed on previous endocrine therapy were stratified by sensitivity to previous hormonal therapy, menopausal status, and presence of visceral metastasis at 144 centres in 17 countries. Eligible patients-ie, any menopausal status, Eastern Cooperative Oncology Group performance status 0-1, measurable disease or bone disease only, and disease relapse or progression after previous endocrine therapy for advanced disease during treatment or within 12 months of completion of adjuvant therapy-were randomly assigned (2:1) via a centralised interactive web-based and voice-based randomisation system to receive oral palbociclib (125 mg daily for 3 weeks followed by a week off over 28-day cycles) plus 500 mg fulvestrant (intramuscular injection on days 1 and 15 of cycle 1; then on day 1 of subsequent 28-day cycles) or placebo plus fulvestrant. The primary endpoint was investigator-assessed progression-free survival. Analysis was by intention to treat. We also assessed endocrine therapy resistance by clinical parameters, quantitative hormone-receptor expression, and tumour PIK3CA mutational status in circulating DNA at baseline. This study is registered with ClinicalTrials.gov, NCT01942135.
Between Oct 7, 2013, and Aug 26, 2014, 521 patients were randomly assigned, 347 to fulvestrant plus palbociclib and 174 to fulvestrant plus placebo. Study enrolment is closed and overall survival follow-up is in progress. By March 16, 2015, 259 progression-free-survival events had occurred (145 in the fulvestrant plus palbociclib group and 114 in the fulvestrant plus placebo group); median follow-up was 8·9 months (IQR 8·7-9·2). Median progression-free survival was 9·5 months (95% CI 9·2-11·0) in the fulvestrant plus palbociclib group and 4·6 months (3·5-5·6) in the fulvestrant plus placebo group (hazard ratio 0·46, 95% CI 0·36-0·59, p<0·0001). Grade 3 or 4 adverse events occurred in 251 (73%) of 345 patients in the fulvestrant plus palbociclib group and 38 (22%) of 172 patients in the fulvestrant plus placebo group. The most common grade 3 or 4 adverse events were neutropenia (223 [65%] in the fulvestrant plus palbociclib group and one [1%] in the fulvestrant plus placebo group), anaemia (ten [3%] and three [2%]), and leucopenia (95 [28%] and two [1%]). Serious adverse events (all causalities) occurred in 44 patients (13%) of 345 in the fulvestrant plus palbociclib group and 30 (17%) of 172 patients in the fulvestrant plus placebo group. PIK3CA mutation was detected in the plasma DNA of 129 (33%) of 395 patients for whom these data were available. Neither PIK3CA status nor hormone-receptor expression level significantly affected treatment response.
Fulvestrant plus palbociclib was associated with significant and consistent improvement in progression-free survival compared with fulvestrant plus placebo, irrespective of the degree of endocrine resistance, hormone-receptor expression level, and PIK3CA mutational status. The combination could be considered as a therapeutic option for patients with recurrent hormone-receptor-positive, HER2-negative metastatic breast cancer that has progressed on previous endocrine therapy.
Pfizer.
Cristofanilli M
，Turner NC
，Bondarenko I
，Ro J
，Im SA
，Masuda N
，Colleoni M
，DeMichele A
，Loi S
，Verma S
，Iwata H
，Harbeck N
，Zhang K
，Theall KP
，Jiang Y
，Bartlett CH
，Koehler M
，Slamon D
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