The effects of adding palbociclib to endocrine therapy to treat advanced breast cancer: a plain language summary of a study using the PALOMA-2 and PALOMA-3 trial results

WHAT IS THIS SUMMARY ABOUT?

This is a summary of an article that reported results of a study using data from two phase 3 clinical trials called "PALOMA-2" and "PALOMA-3." Both PALOMA-2 and PALOMA-3 trials included women with HR+/HER2- advanced breast cancer. HR+/HER2- breast cancer means the breast cancer cells of these women have receptors for female sex hormones and little or no HER2 receptors. Both PALOMA trials tested the effect of adding a medication called palbociclib (brand name, Ibrance®) to a hormone therapy. Hormone therapy, also known as endocrine therapy, is a treatment that blocks or removes hormones that cause cancer cells to grow and divide. In both trials, women took endocrine therapy with either palbociclib or a placebo.

WHAT WAS THE AIM OF THIS STUDY?

The researchers aimed to see if the results from the PALOMA trials were similar for subgroups of women in the 2 trials. The subgroups in the study included women who shared certain features about their cancer or treatment history, for example, women whose cancer had spread to the liver. For each subgroup, the study compared the results from the 2 treatment groups: (1) women who took palbociclib plus endocrine therapy, and (2) women who took placebo plus endocrine therapy.

WHAT WERE THE RESULTS & WHAT DO THEY MEAN?

The same effect was found in all subgroups. Compared with those who took placebo, women who took palbociclib lived longer without their cancer getting worse (growing or spreading). Also, among women who had chemotherapy after stopping the trial treatment, those who took palbociclib started chemotherapy later than those who took placebo. Because palbociclib slows cancer growth and leads to tumor shrinkage, this may have played a part in starting chemotherapy later. These results show that palbociclib plus endocrine therapy is better at slowing the progression of advanced HR+/HER2- breast cancer than endocrine therapy alone. This can be said for women with different advanced HR+/HER2- breast cancer features and treatment history. Overall, the results support women taking palbociclib with an endocrine therapy if they have advanced HR+/HER2- breast cancer.

HR+/HER2- Advanced Breast Cancer Treatment in the First-Line Setting: Expert Review

The approval of CDK4/6 inhibitors has dramatically improved care for the treatment of HR+/HER2- advanced breast cancer, but navigating the rapidly-expanding treatment evidence base is challenging. In this narrative review, we provide best-practice recommendations for the first-line treatment of HR+/HER2- advanced breast cancer in Canada based on relevant literature, clinical guidelines, and our own clinical experience. Due to statistically significant improvements in overall survival and progression-free survival, ribociclib + aromatase inhibitor is our preferred first-line treatment for de novo advanced disease or relapse ≥12 months after completion of adjuvant endocrine therapy and ribociclib or abemaciclib + fulvestrant is our preferred first-line treatment for patients experiencing early relapse. Abemaciclib or palbociclib may be used when alternatives to ribociclib are needed, and endocrine therapy can be used alone in the case of contraindication to CDK4/6 inhibitors or limited life expectancy. Considerations for special populations-including frail and fit elderly patients, as well as those with visceral disease, brain metastases, and oligometastatic disease-are also explored. For monitoring, we recommend an approach across CDK4/6 inhibitors. For mutational testing, we recommend routinely performing ER/PR/HER2 testing to confirm the subtype of advanced disease at the time of progression and to consider ESR1 and PIK3CA testing for select patients. Where possible, engage a multidisciplinary care team to apply evidence in a patient-centric manner.

Prolonging the life of people with metastatic breast cancer in routine clinical practice by adding palbociclib to an aromatase inhibitor from a real-world database analysis: a plain language summary

WHAT IS THIS SUMMARY ABOUT?

This is a summary of an article about a study called "P-REALITY X" that was published in the medical journal npj Breast Cancer in October 2022. "P-REALITY X" stands for Palbociclib REAl-world first-LIne comparaTive effectiveness studY eXtended. This study used information from a database to look at whether adding a second treatment (palbociclib) to an aromatase inhibitor (AI) helped people with a certain type of breast cancer to live longer. The type of breast cancer is metastatic hormone receptor-positive/human epidermal growth factor-negative breast cancer, also called HR-positive (or HR+)/HER2-negative (or HER2-) breast cancer. The study used information from the Flatiron Database. This database contains unidentified health care information collected from people seen by doctors in the USA. Only data from people who did not participate in a clinical trial were used. When people are treated outside of a clinical trial, this is called the real-world setting, or routine clinical practice. In clinical trials, people lived longer without their disease worsening if they were treated with palbociclib plus an AI versus being treated with an AI only. Based on the results of clinical trials, treatment with palbociclib plus an AI is already approved and recommended for people with HR+/HER2- breast cancer. This study looked at whether people lived longer if they were treated with palbociclib plus an AI versus being treated with an AI only in routine clinical practice as well.

WHAT WERE THE RESULTS?

This study showed that, in routine clinical practice, people treated with the medicine palbociclib plus an AI lived longer than people treated with only an AI.

WHAT DO THE RESULTS MEAN?

These results support the continued use of palbociclib plus an AI as the standard first medicine to be given to people with metastatic HR+/HER2- breast cancer. Clinical Trial Registration: NCT05361655 (ClinicalTrials.gov).

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

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

Health-Related Quality of Life Among Patients With HR+/HER2- Early Breast Cancer

PURPOSE

The goal of this study was to characterize health-related quality of life (HRQOL) among patients diagnosed with early-stage, hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) breast cancer.

METHODS

A multinational (United States, Japan, France, Germany, Italy, Spain, and United Kingdom) study of patients diagnosed with stage I to III HR+/HER2- breast cancer, either receiving adjuvant treatment or under postadjuvant surveillance, was conducted between June and October 2019. Patients were identified by their consulting physician and invited to complete the Functional Assessment of Cancer Therapy-Breast (FACT-B) and the EQ-5D-5L pen and paper questionnaires. EQ-5D-5L index scores were derived by using available country-specific health state value sets, where available, and numerically compared with general population scores derived from published normative and population data. Descriptive summary statistics were reported for FACT-B, Functional Assessment of Cancer Therapy-General (FACT-G) (total and specific subscales), the EQ-5D index scores, and the EQ-VAS scores for each country. Results were stratified according to disease-free treatment status (active adjuvant treatment or postadjuvant surveillance), age (25-44, 45-54, 55-64, or ≥65 years), stage (I, II, or III), and menopausal status at the time of questionnaire completion (pre-/peri-menopausal or postmenopausal).

FINDINGS

Overall, 1110 patients completed the HRQOL questionnaires (mean age, 59 years; 79% active adjuvant treatment, and 21% under surveillance postadjuvant treatment at time of questionnaire administration; 31% stage I, 48% stage II, and 20% stage III at diagnosis). Of these, 1102 completed the FACT-B and 1083 completed the EQ-5D-5L questionnaires. The mean (SD) FACT-B total score was 99.0 (21.9). The mean FACT-G total score was 72.5 (17.8), which was comparable to the published normative score. The mean EQ-5D index and EQ-VAS scores for each country were similar to corresponding population means; EQ-5D index scores ranged from 0.842 (0.098) in Japan to 0.916 (0.109) in France, and EQ-VAS scores from 68.0 (18.4) in Germany to 78.6 (16.4) in the United States. In addition, mean scores were comparable between the active adjuvant treatment and postadjuvant surveillance groups for the FACT-B total (99.4 [22.5] and 97.7 [19.7], respectively), FACT-G total (72.8 [18.3] and 71.3 [16.0]), EQ-5D index score (0.868 [0.135] and 0.869 [0.142]), and EQ-VAS (74.9 [17.2] and 74.4 [16.1]).

IMPLICATIONS

Patient-reported HRQOL among patients with HR+/HER2- early breast cancer who were disease-free was high, with reported scores comparable to normative scores. These results improve our understanding of HRQOL among patients with early disease and may facilitate future studies examining the potential impact of adjuvant treatment and disease recurrence, including metastasis.

Predictors of prolonged benefit from palbociclib plus fulvestrant in women with endocrine-resistant hormone receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer in PALOMA-3

BACKGROUND

The addition of palbociclib to fulvestrant improved clinical outcomes over placebo-fulvestrant in endocrine-pretreated metastatic breast cancer (MBC) patients in PALOMA-3. Here, we examined factors predictive of long-term benefit.

METHODS

Premenopausal-peri/postmenopausal patients with endocrine-resistant, hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative MBC were randomised 2:1 to fulvestrant (500 mg) and either palbociclib (125 mg/d; 3/1 schedule; n = 347) or placebo (n = 174). Baseline characteristics, mutation status and HR expression levels were compared in patients with and without prolonged benefit (treatment duration ≥18 months).

RESULTS

By August 2016, 100 patients (29%) on palbociclib-fulvestrant and 26 (15%) on placebo-fulvestrant demonstrated prolonged benefit, with long-term responders in both arms sharing common clinical characteristics. They usually had less disease burden at baseline versus those treated <18 months, such as having one disease site (40% vs 29% on palbociclib-fulvestrant and 69% vs 29% on placebo-fulvestrant), bone-only disease (32% vs 22% and 46% vs 17%) and were less heavily pretreated (69% vs 56% and 73% vs 60% had ≤2 prior therapies). Baseline tumour ESR1 and PIK3CA mutation rates were lower among long-term responders in both arms; median oestrogen receptor H-scores were similar, whereas progesterone receptor H-scores were higher among long-term responders.

CONCLUSIONS

This exploratory analysis demonstrates that some patients with endocrine-resistant MBC derive significant and prolonged benefit when treated with palbociclib-fulvestrant, with fewer patients experiencing similar efficacy with placebo-fulvestrant. The current analysis did not identify specific molecular or clinical factors prognostic of long-term benefit with palbociclib-fulvestrant (ClinicalTrials.gov, NCT01942135).

First-line treatment disruption among post-menopausal women with HR+/HER2- metastatic breast cancer: a retrospective US claims study

OBJECTIVE

This study assessed disruption of first-line treatments initiated after the approval of the first CDK 4/6 inhibitor, palbociclib, among post-menopausal women with HR+/HER2- metastatic breast cancer (mBC) in the US.

METHODS

Post-menopausal women with HR+/HER2- mBC who initiated first-line endocrine therapy or chemotherapy (index therapy) between February 3, 2015 (palbociclib approval date) and February 29, 2016 (end of data) were identified from the Symphony Source Lx database. Patients were required to have continuous quarterly activity (defined as ≥1 pharmacy or medical claim) for 12 months prior to and 1 month after the initiation of the index therapy (index date). Treatment disruption was defined as a treatment gap of ≥60 days or adding an agent after the original therapy. Kaplan-Meier analyses were conducted to estimate treatment disruption rates during the 6 months following the index date. Patients without treatment disruption were censored at the end of continuous quarterly activity or end of data.

RESULTS

A total of 8,160 and 2,153 eligible patients initiated endocrine therapy or chemotherapy as their first-line mBC treatment, with a median follow-up of 6.7 and 7.6 months, respectively. The three most prevalent metastatic sites were bone (28.1-42.2%), liver (8.8-17.3%), and lung (8.6-9.5%). Overall, 37.7% (n = 3,074) of patients receiving endocrine therapy and 86.1% (n = 1,852) of patients receiving chemotherapy encountered treatment disruption at 6 months (log-rank test p < .05).

CONCLUSIONS

Treatment disruption rates of first-line therapies were sub-optimal among post-menopausal women with HR+/HER2- mBC, primarily driven by chemotherapy users. New therapies or interventions are needed to reduce treatment disruption in this patient population.