FDA Approval Summary: Ribociclib Indicated for Male Patients with Hormone Receptor-Positive, HER2-Negative Advanced or Metastatic Breast Cancer.

On December 10, 2021, the FDA expanded the indications for ribociclib to include male patients for the treatment of hormone receptor-positive, HER2-negative advanced or metastatic breast cancer. Ribociclib is now indicated in combination with an aromatase inhibitor (AI) as initial endocrine-based therapy in adult patients, or with fulvestrant as initial endocrine-based therapy or following disease progression on endocrine therapy (ET), in postmenopausal women or in men. The efficacy of ribociclib + AI for male patients was primarily based on previous favorable benefit-risk assessments of ribociclib from MONALEESA-2 and MONALEESA-7 trials, and supported by COMPLEEMENT-1, an open-label, single-arm, multicenter clinical trial, in which 39 male patients (n = 3,246 total patients) received ribociclib + letrozole + goserelin/leuprolide. The overall response rate (ORR) based on confirmed responses in male patients with measurable disease at baseline was 46.9% [95% confidence interval (CI), 29.1-65.3], consistent with an ORR of 43.6% (95% CI, 41.5-45.8) in the overall population. Overall, adverse reactions occurring in male patients were similar to those occurring in female patients treated with ribociclib + ET. The efficacy of ribociclib + fulvestrant for male patients was primarily based on the previous findings of a favorable benefit-risk assessment from the MONALEESA-3 trial, supported by FDA review of clinical data of a limited number of male patients treated in clinical practice receiving ribociclib + fulvestrant. The known mechanism of action, biologic rationale, and clinical information available adequately demonstrate that the efficacy and safety of ribociclib + AI/fulvestrant are similar in male and female patients. This article summarizes the FDA's decision-making and data supporting the approval of ribociclib in male patients with breast cancer, and discusses regulatory insights.

US Food and Drug Administration Analysis of Patient-Reported Diarrhea and Its Impact on Function and Quality of Life in Patients Receiving Treatment for Breast Cancer.

OBJECTIVES: Many trials conclude "no clinically meaningful detriment" to health-related quality of life (HRQL) or function between arms, even when notable differential toxicity is observed. Mean change from baseline analyses of function or HRQL can possibly obscure important change in subgroups experiencing symptomatic toxicity. We evaluate the impact of diarrhea, a key treatment arm toxicity, on patient-reported HRQL and functioning in clinical trials submitted to US Food and Drug Administration. METHODS: This study used 4 randomized, breast cancer trials (adjuvant to late-line metastatic) as case examples. Diarrhea, physical functioning (PF), and global health status and quality of life (GHS/QoL) from the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-C30 were analyzed at baseline and approximately 3 and 6 months. RESULTS: Generally, patients reporting very much diarrhea at months 3 and 6 had worse PF (9-19 points lower) and GHS/QoL (16-19 points lower) than patients reporting no diarrhea regardless of treatment arm. In the change from baseline analysis, patients reporting very much diarrhea also experienced a greater decrease in PF (6-13 points) and GHS/QoL (6-16 points) versus patients reporting no diarrhea in both arms. CONCLUSIONS: In trials with moderate to large differences in symptomatic toxicity by arm, reporting "no meaningful difference in functioning and HRQL between arms" based on mean change from baseline analysis is insufficient and may obscure important impacts on subgroups experiencing symptomatic adverse events. Additional exploratory analyses with simple data visualizations evaluating functioning or HRQL in patient subgroups experiencing expected symptomatic toxicities can further inform the safety and tolerability of an investigational agent.

U.S. FDA Drug Approvals for Gynecological Malignancies: A Decade in Review.

Over the last decade, there has been tremendous progress in the treatment of patients with gynecologic cancers with a changing therapy landscape. This summary provides an overview of U.S. Food and Drug Administration (FDA) approvals for gynecologic cancers from 2010 to 2020, totaling 17 new indications. For each of the approved indications, endpoints, trial design, results, and regulatory considerations are outlined. Among these 17 indications, six received accelerated approval (AA) and 11 received regular approval (RA). As of September 2021, of the six AA, three have subsequently demonstrated clinical benefit resulting in conversion to RA and the remaining three have ongoing clinical trials that have not yet reported results. Approval decisions for these 17 indications were supported by primary efficacy endpoints of progression-free survival (n = 10), objective response rate (n = 6), and overall survival (n = 1) and showed a favorable benefit-risk profile. Among the 17 indications, 15 received priority review and three applications participated in one or more novel Oncology Center of Excellence initiatives, including Real Time Oncology Review, Assessment Aid, and Project Orbis. Current FDA thinking on drug development opportunities and regulatory initiatives currently under way will be discussed.

U.S. FDA Drug Approvals for Breast Cancer: A Decade in Review.

Over the last decade, the treatment of patients with breast cancer has been greatly impacted by the approval of multiple drugs and indications. This summary describes 30 FDA approvals of treatments for breast cancer from 2010 to 2020. The trial design endpoints, results, and regulatory considerations are described for each approved indication. Of the 30 indications, 23 (76.6%) received regular and 7 (23.3%) received accelerated approval. Twenty-six approvals were granted in metastatic breast cancer (MBC) and four in early breast cancer. Approval decisions for the 26 MBC indications were initially supported by progression-free survival (PFS) in 21 (80.8%), overall survival (OS) or a combination of OS and PFS in two (7.7%), and objective response rate (ORR) in three (11.5%). The four approvals in early breast cancer utilized pathologic complete response (pCR) in one (25%) and invasive disease-free survival (iDFS) in three (75%) trials. Among the 30 indications, 22 received priority review, seven were granted Breakthrough Therapy Designation, and 10 applications participated in one or more pilot Oncology Center of Excellence regulatory review initiatives, including Real Time Oncology Review, Assessment Aid, and Project Orbis. FDA initiatives to advance breast cancer drug development are also described.

Overall survival in patients with hormone receptor-positive, HER2-negative, advanced or metastatic breast cancer treated with a cyclin-dependent kinase 4/6 inhibitor plus fulvestrant: a US Food and Drug Administration pooled analysis.

BACKGROUND: Cyclin-dependent kinase 4/6 inhibitors (CDKIs) are oral targeted agents approved for use in combination with endocrine therapy as first-line or second-line treatment of patients with hormone receptor-positive, HER2-negative, advanced or metastatic breast cancer. We previously reported the pooled analyses of progression-free survival in patients in specific clinicopathological subgroups, all of whom received consistent benefit from the addition of a CDKI to hormonal therapy. Here, we report the pooled overall survival results in patients treated with a CDKI and fulvestrant. METHODS: In this exploratory analysis, we pooled individual patient data from three phase 3 randomised trials of CDKI or placebo in combination with fulvestrant in patients with breast cancer submitted to the US Food and Drug Administration and approved before Aug 1, 2020, in support of marketing applications. All analysed patients were aged at least 18 years, had an Eastern Cooperative Oncology Group performance status of 0-1, had hormone receptor-positive, HER2-negative advanced or metastatic breast cancer, and received at least one dose of CDKI or placebo in combination with fulvestrant. The median overall survival was estimated using Kaplan-Meier methods, and hazard ratios (HRs) with corresponding 95% CIs were estimated using Cox regression models. Patients were analysed collectively, by number of previous lines of systemic endocrine therapy in any disease setting (first-line or endocrine naive vs second-line and later), and in various clinicopathological subgroups of interest. The estimated median overall survival was not reported by group when the pooled population included patients treated across lines of therapy because of potential patient heterogeneity. All results presented are considered exploratory and hypothesis generating. FINDINGS: Across the three pooled trials, 1960 patients were randomly assigned between Oct 7, 2013, and June 10, 2016 (12 patients were not treated and 1296 [66%] patients were randomly assigned to CDKI and 652 [33%] to placebo). In all treated patients (n=1948), the estimated HR for overall survival was 0·77 (95% CI 0·68-0·88), with a median follow-up of 43·7 months (IQR 37·8-47·7) and deaths in 935 (48%) of the 1948 patients. The difference in estimated median overall survival was 7·1 months, favouring CDKIs. In patients who received CDKIs or placebo in combination with fulvestrant as first-line systemic endocrine therapy (two trials; n=396), the estimated HR for overall survival was 0·74 (95% CI 0·52-1·07), with a median follow-up of 39·4 months (IQR 37·0-42·2). 123 (31%) of these patients died. The difference in estimated median overall survival could not be calculated because median overall survival was not estimable (95% CI 50·9-not estimable) in the CDKI group and was 45·7 months (95% CI 41·7-not estimable) in the placebo group. In patients who received CDKIs or placebo in combination with fulvestrant as second-line or later systemic endocrine therapy (three trials; n=1552), the estimated HR for overall survival was 0·77 (95% CI 0·67-0·89), with a median follow-up of 45·1 months (95% CI 39·2-48·5). 812 (52%) of these patients died. The difference in estimated median overall survival was 7·0 months, favouring CDKIs. INTERPRETATION: The addition of CDKIs to fulvestrant resulted in a consistent overall survival benefit in all pooled patients and within most clinicopathological subgroups of interest. These findings support the existing standard of care of CDKIs plus fulvestrant for the treatment of patients with hormone receptor-positive, HER2-negative, advanced breast cancer. FUNDING: None.

Model Development of CDK4/6 Predicted Efficacy in Patients With Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced or Metastatic Breast Cancer.

PURPOSE: Three cyclin-dependent kinase 4/6 inhibitors (CDKIs) are approved by the US Food and Drug Administration for the treatment of patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced or metastatic breast cancer in combination with hormonal therapy (HT). We hypothesized that on an individual basis, efficacy outcomes and adverse event (AE) development can be predicted using baseline patient and tumor characteristics. METHODS: Individual-level data from seven randomized controlled trials submitted to the US Food and Drug Administration for new or supplemental marketing applications of CDKIs were pooled. Progression-free survival (PFS), overall survival (OS), and AE prediction models were developed for specific treatment regimens (HT v HT plus CDKI). An individual's characteristics were used in all models simultaneously to create a group of predicted outcomes that are comparable across treatment settings. RESULTS: Accuracy of the PFS and OS prediction models for HT were 66% and 64%, respectively, with the strongest predictors being menopausal status and therapy line. The corresponding AE prediction models resulted in an average area under the curve of 0.613. Accuracy of the PFS and OS prediction models for HT plus CDKI were 62% and 63%, respectively, with the strongest predictors being histologic grade for both. The corresponding AE prediction models resulted in an average area under the curve of 0.639. CONCLUSION: This exploratory analysis demonstrated that models of efficacy outcomes and AE development can be developed using baseline patient and tumor characteristics. Comparison of paired models can inform treatment selection for individuals on the basis of the patient's personalized goals and concerns. Although use of CDKIs is standard of care in the first- or second-line setting, this model provides prognostic information that may inform individual treatment decisions.

FDA Approval Summary: Pertuzumab, Trastuzumab, and Hyaluronidase-zzxf Injection for Subcutaneous Use in Patients with HER2-positive Breast Cancer.

On June 29, 2020, the FDA approved pertuzumab, trastuzumab, and hyaluronidase-zzxf subcutaneous injection (Phesgo) for the treatment of patients with HER2-positive early-stage and metastatic breast cancer. Patients should be selected for therapy based on an FDA-approved companion diagnostic test. Approval was primarily based on the FeDeriCa trial, a randomized, open-label, multicenter comparability study of pertuzumab, trastuzumab, and hyaluronidase-zzxf subcutaneous injection compared with intravenous pertuzumab and intravenous trastuzumab administered in the neoadjuvant and adjuvant settings with chemotherapy for the treatment of patients with early breast cancer. The pharmacokinetic endpoints were, first, to demonstrate that the exposure of subcutaneous pertuzumab was not inferior to that of intravenous pertuzumab, and then to demonstrate that the exposure of subcutaneous trastuzumab was not inferior to that of intravenous trastuzumab. The primary endpoints were met with the observed lower limit of the two-sided 90% confidence intervals above the prespecified noninferiority margins. The most common adverse reactions were alopecia, nausea, diarrhea, anemia, and asthenia. The totality of the evidence demonstrated comparability of the subcutaneous product to intravenous, allowing for extrapolation and approval of all breast cancer indications for which intravenous trastuzumab and pertuzumab are approved.

FDA Oncology Center of Excellence Project Renewal: Engaging the Oncology Community to Update Product Labeling for Older Oncology Drugs.

The FDA conducts independent reviews of scientific data obtained with investigational drug products to ensure that they are safe and effective. As a result of this process, FDA-approved product labeling is generated that is considered one of the most trusted sources of information for use of an approved drug. But FDA approval is only the beginning of the life cycle of a new drug; the first oncology drugs now have more than 7 decades of clinical experience in the postmarketing setting. Due, in part, to lack of incentives, some companies may not seek inclusion of new data, other than new safety information, in FDA-approved product labeling. Ensuring that product labeling provides adequate directions for use is important for all drugs, including older therapies that may form the backbone of many standard combination regimens for pediatric and adult cancers. Project Renewal is an FDA Oncology Center of Excellence pilot program that leverages expertise from the clinical and scientific oncology communities to review published literature and generate a drug-specific product report summarizing data that may support updates to FDA-approved product labeling. This article provides a broad overview of Project Renewal's collaborative pilot process for identifying and assessing literature supporting potential labeling updates, while engaging the oncology community to increase awareness of FDA's evidentiary standards and deliberative processes used when considering the addition of new indications and dosing regimens to product labeling.

FDA Approval Summary: Alpelisib Plus Fulvestrant for Patients with HR-positive, HER2-negative, PIK3CA-mutated, Advanced or Metastatic Breast Cancer.

On May 24, 2019, the FDA granted regular approval to alpelisib in combination with fulvestrant for postmenopausal women, and men, with hormone receptor (HR)-positive, HER2-negative, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-mutated, advanced or metastatic breast cancer as detected by an FDA-approved test following progression on or after an endocrine-based regimen. Approval was based on the SOLAR-1 study, a randomized, double-blind, placebo-controlled trial of alpelisib plus fulvestrant versus placebo plus fulvestrant. The primary endpoint was investigator-assessed progression-free survival (PFS) per RECIST v1.1 in the cohort of trial participants whose tumors had a PIK3CA mutation. The estimated median PFS by investigator assessment in the alpelisib plus fulvestrant arm was 11 months [95% confidence interval (CI), 7.5-14.5] compared with 5.7 months (95% CI, 3.7-7.4) in the placebo plus fulvestrant arm (HR, 0.65; 95% CI, 0.50-0.85; two-sided P = 0.001). The median overall survival was not yet reached for the alpelisib plus fulvestrant arm (95% CI, 28.1-NE) and was 26.9 months (95% CI, 21.9-NE) for the fulvestrant control arm. No PFS benefit was observed in trial participants whose tumors did not have a PIK3CA mutation (HR, 0.85; 95% CI, 0.58-1.25). The most common adverse reactions, including laboratory abnormalities, on the alpelisib plus fulvestrant arm were increased glucose, increased creatinine, diarrhea, rash, decreased lymphocyte count, increased gamma glutamyl transferase, nausea, increased alanine aminotransferase, fatigue, decreased hemoglobin, increased lipase, decreased appetite, stomatitis, vomiting, decreased weight, decreased calcium, decreased glucose, prolonged activated partial thromboplastin time, and alopecia.

FDA Approval Summary: Olaparib Monotherapy or in Combination with Bevacizumab for the Maintenance Treatment of Patients with Advanced Ovarian Cancer.

On December 19, 2018, the U.S. Food and Drug Administration (FDA) granted approval to olaparib monotherapy for first-line maintenance treatment of BRCA-mutated (BRCAm) advanced ovarian cancer and, on May 8, 2020, expanded the indication of olaparib to include its use in combination with bevacizumab for first-line maintenance treatment of homologous recombination deficient (HRD)-positive advanced ovarian cancer. Both these approvals were based on randomized, double-blind, placebo-controlled trials. Approval for olaparib monotherapy was based on the SOLO-1 trial, comparing the efficacy of olaparib versus placebo in patients with BRCAm advanced ovarian, fallopian tube, or primary peritoneal cancer after surgical cytoreduction and first-line platinum-based chemotherapy. Two companion diagnostic (CDx) tests were approved with this indication: BRACAnalysis CDx, for germline BRCA1/2 alterations, and FoundationOne CDx, for BRCA1/2 alterations in tissue specimens. Approval for olaparib in combination with bevacizumab was based on the results of the PAOLA-1 trial that compared olaparib with bevacizumab versus placebo plus bevacizumab in patients with advanced high-grade epithelial ovarian cancer, fallopian tube, or primary peritoneal cancer after first-line platinum-based chemotherapy and bevacizumab. Myriad myChoice CDx was designated as a companion diagnostic device for use of olaparib plus bevacizumab combination for ovarian cancer associated with HRD-positive status. Both trials demonstrated clinically meaningful improvements in progression-free survival and favorable benefit-risk profiles for the indicated populations. This article summarizes the FDA thought process and data supporting the approval of olaparib as monotherapy and in combination with bevacizumab for maintenance therapy in this setting. IMPLICATIONS FOR PRACTICE: These approvals represent the first poly (ADP-ribose) polymerase inhibitor, alone or in combination with bevacizumab, approved in first-line maintenance treatment of women with advanced ovarian cancer after cytoreductive surgery and chemotherapy. In patients with BRCA-mutated tumors, olaparib monotherapy demonstrated a 70% reduction in the risk of disease progression or death compared with placebo, and olaparib in combination with bevacizumab demonstrated a 67% reduction in the risk of disease progression or death compared with bevacizumab alone in homologous recombination deficient-positive tumors. These approvals represent a major advance for the treatment of women with advanced ovarian cancer who are in complete or partial response after their initial platinum-based chemotherapy.

U.S. Food and Drug Administration: Initial Experience with the Real-Time Oncology Review Program.

The FDA Oncology Center of Excellence commenced the Real-Time Oncology Review (RTOR) pilot project in February 2018 to facilitate earlier submission of topline results and datasets to support an earlier start to the FDA application review. RTOR was initially begun to support supplemental drug applications to add new indications, dosing regimens, or other clinical information to the prescribing information, but was later expanded to include original new drug applications and biological license applications for new molecular entities (NME). From February 2018 to April 2020, RTOR was used to support the submission and review of drug approvals for 20 oncology applications (11 for solid tumor and nine for hematologic malignancy indications). Two were NME drug approvals and 18 were supplemental approvals. All of the applications received priority review and nine (45%) applications had received breakthrough therapy designation status. FDA received the RTOR submissions a median of 5.7 weeks (range 1.7-16.2 weeks) prior to the full application submission. The median time from application submission to FDA approval was 3.3 months (range 0.4-5.9 months). RTOR was also integrated with other review programs including the Assessment Aid and Project Orbis programs. Innovative regulatory processes are critical to expedite the rigorous review of impactful products across the FDA.

FDA Approval Summary: Atezolizumab Plus Paclitaxel Protein-bound for the Treatment of Patients with Advanced or Metastatic TNBC Whose Tumors Express PD-L1.

On March 8, 2019, the FDA granted accelerated approval to atezolizumab in combination with paclitaxel protein-bound for the treatment of adult patients with unresectable locally advanced or metastatic triple-negative breast cancer (TNBC) whose tumors express PD-L1 [PD-L1 stained tumor-infiltrating immune cells (IC) of any intensity covering ≥1% of the tumor area], as determined by an FDA-approved test. Approval was based on data from IMpassion130, which randomized patients to receive atezolizumab or placebo in combination with paclitaxel protein-bound. Investigator-assessed progression-free survival (PFS) in the intent-to-treat (ITT) and PD-L1-positive populations were coprimary endpoints. After 13-month median follow-up, the estimated median PFS in the PD-L1-positive population was 7.4 months in the atezolizumab arm and 4.8 months in the placebo arm [HR = 0.60; 95% confidence interval (CI), 0.48-0.77]. Overall survival (OS) results were immature with 43% deaths in the ITT population, representing 59% of the OS events required to perform the final OS analysis. Adverse reactions occurring in ≥20% of patients receiving atezolizumab with paclitaxel protein-bound were alopecia, peripheral neuropathies, fatigue, nausea, diarrhea, anemia, constipation, cough, headache, neutropenia, vomiting, and decreased appetite. Accelerated approval was appropriate taking into account the unmet medical need along with the immaturity of the OS results and potential for PFS in the PD-L1-expressing population to predict clinical benefit.

CDK4/6 inhibitor treatment for patients with hormone receptor-positive, HER2-negative, advanced or metastatic breast cancer: a US Food and Drug Administration pooled analysis.

BACKGROUND: Cyclin-dependent kinase 4/6 inhibitors (CDKIs) are indicated with endocrine therapy as first-line or second-line treatment for hormone receptor-positive, HER2-negative, advanced or metastatic breast cancer. We aimed to investigate the benefit of adding CDKIs to endocrine therapy in patients whose tumours might have differing degrees of endocrine sensitivity. METHODS: We pooled individual patient data from all phase 3 randomised breast cancer trials of CDKIs plus endocrine therapy submitted to the US Food and Drug Administration before Jan 1, 2019, in support of marketing applications. Our pooled analysis included all randomly assigned patients in these trials who received at least one dose of CDKI or placebo with endocrine therapy (an aromatase inhibitor [letrozole or anastrazole] or fulvestrant). We did prespecified subgroup analyses in patients with progesterone receptor-negative disease; patients with a disease-free interval of 12 months or less; patients with de-novo metastases, lobular histology, and bone-only disease; patients with visceral metastases; and patients aged up to 40 years. Patients who were not treated, who received tamoxifen as endocrine therapy, or who were treated with an aromatase inhibitor but who had received previous chemotherapy in the metastatic setting (not first-line) were excluded from our pooled analyses. All studies had a primary endpoint of investigator-assessed progression-free survival, defined as time from date of randomisation to the initial date of documented cancer progression or death, whichever occurred first. Median progression-free survival was estimated with Kaplan-Meier methods. Hazard ratios (HR) with 95% CIs for progression-free survival were estimated by means of Cox regression models. FINDINGS: The seven studies meeting this study's inclusion criteria were done between Feb 22, 2013, and Nov 3, 2017, with a median duration of follow-up of 19·7 months (IQR 15·9-25·9). 4200 patients were included in the pooled analysis, of whom 1320 received an aromatase inhibitor plus a CDKI, 932 received placebo plus an aromatase inhibitor, 1296 received fulvestrant plus a CDKI, and 652 received fulvestrant plus placebo. Across all seven pooled trials, the difference in estimated median progression-free survival was 8·8 months in favour of CDKI plus endocrine therapy over placebo plus endocrine therapy (range across the trials 6·8-13·3 months; HR 0·59, 95% CI 0·54-0·64). Progression-free survival results favoured the CDKI group in all prespecified clinicopathological subgroups analysed, with similar HRs to that for the broader intended-use population. In first-line aromatase inhibitor-treated patients (n=2252), the median progression-free survival in the CDKI plus aromatase inhibitor group was 28·0 months (95% CI 25·3-29·1) versus 14·9 months (14·0-16·7) in the placebo plus aromatase inhibitor group (difference 13·1 months; range across the trials 13·0-13·3 months; HR 0·55, 95% CI 0·49-0·62). In first-line fulvestrant-treated patients (n=396), the median progression-free survival was 18·6 months (95% CI 14·8-23·5) in the placebo plus fulvestrant group and not estimable (22·4 to not estimable) in the CDKI plus fulvestrant group (difference not estimable; HR 0·58, 95% CI 0·42-0·80). In the patients treated with fulvestrant in the second-line setting and beyond (n=1552), the difference in estimated median progression-free survival between the CDKI plus fulvestrant group and the placebo plus fulvestrant group was 6·9 months in favour of the CDKI group (range across the trials 5·5-7·3 months; HR 0·56, 95% CI 0·49-0·64). INTERPRETATION: Since the addition of CDKI to endocrine therapy seemed to benefit all clinicopathological subgroups of interest in this pooled analysis, further research is needed to identify patient subgroups for whom endocrine therapy alone might be appropriate for first-line or second-line treatment of hormone receptor-positive, HER2-negative metastatic breast cancer. FUNDING: None.

Outcomes of Older Women With Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor-Negative Metastatic Breast Cancer Treated With a CDK4/6 Inhibitor and an Aromatase Inhibitor: An FDA Pooled Analysis.

PURPOSE: Many older women will be treated with a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor and an aromatase inhibitor (AI), given US Food and Drug Administration approval of three agents in this class. The current pooled analysis examines the efficacy and safety of this combination in older women. PATIENTS AND METHODS: We pooled data from three randomized controlled studies (N = 1,827) of different CDK4/6 inhibitors in combination with an AI for initial treatment of postmenopausal women with hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer. The effect of age on progression-free survival was evaluated using Kaplan-Meier estimates and a Cox proportional hazards regression model. RESULTS: For patients age 75 years or older (n = 198) who were treated with a CDK4/6 inhibitor and an AI, hazard ratio was 0.49 (95% CI, 0.31 to 0.76) with an estimated median progression-free survival of 31.1 months (95% CI, 20.2 months to not reached) versus 13.7 months (95% CI, 10.9 months to 24.9 months) for those treated with an AI. Incidence of grade 3 to 4 adverse events was 88.8% in patients age 75 years and older and 73.4% in patients younger than age 75 years. Patients age 75 years or older reported a decline in quality-of-life measures using the EQ-5D regardless of treatment with AI alone or with the addition of a CDK4/6 inhibitor. CONCLUSION: There was similar efficacy with a CDK4/6 inhibitor in combination with an AI compared with AI alone for first-line treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer in older women compared with younger patients. Patients older than age 75 years experienced higher rates of toxicity, dose modifications, and a decrease from baseline in quality-of-life measures.

Luminal A Breast Cancer and Molecular Assays: A Review.

PURPOSE: Chemotherapy has been the historical mainstay of treatment for patients with breast cancer, with immunohistochemical markers and tumor characteristics driving treatment decisions. The discovery of different intrinsic subtypes of breast cancer has advanced the understanding of breast cancer, with gene-based assays shedding further light on tumor behavior and response to treatment. DESIGN: This review focuses on the landscape of the luminal A subtype, its definition based on immunohistochemistry (IHC) and gene assays, the prognostic and predictive value of these assays, guideline recommendations, and treatment implications. RESULTS: Clinical studies of the prognostic value of gene-based and IHC-based assays in patients with luminal A-subtype breast cancers suggest a better prognosis for these patients compared with those with breast cancers of other subtypes. CONCLUSION: In today's era of precision medicine, the best treatment regimen for patients with luminal A-subtype tumors is still undetermined, but available data raise the question whether chemotherapy can be omitted and endocrine therapy alone is sufficient for this patient population. IMPLICATIONS FOR PRACTICE: Immunohistochemical markers have traditionally guided treatment decisions in breast cancer. However, advances in gene-expression profiling and availability of gene-based assays have launched these newer tests into everyday clinical practice. Luminal A-subtype tumors are a unique subset that may have favorable tumor biology. Properly defining this tumor subtype is important and may identify a subset of patients for whom endocrine therapy alone is sufficient.