Prospective Evaluation of Circulating Tumor DNA using Next Generation Sequencing as a Biomarker during Neoadjuvant Chemotherapy in Localized Pancreatic Cancer.

OBJECTIVE: In this prospective study, we aim to characterize the prognostic value of circulating tumor DNA (ctDNA) by next-generation-sequencing (NGS) in patients undergoing neoadjuvant chemotherapy (NAC) for pancreatic ductal adenocarcinoma (PDAC). SUMMARY BACKGROUND DATA: Circulating tumor DNA is a promising blood-based biomarker that is prognostic in several malignancies. Detection of ctDNA by NGS may provide insights regarding the mutational profiles in PDAC to help guide clinical decisions for patients in a potentially curative setting. However, the utility of ctDNA as a biomarker in localized PDAC remains unclear. METHODS: Patients with localized PDAC were enrolled in a prospective study at Northwestern Medicine between October 2020 and October 2022. Blood samples were collected to perform targeted tumor agnostic NGS utilizing the Tempus x|F 105 gene panel at three timepoints: pre-therapy (at diagnosis), post-NAC, and after local therapy, including surgery. The relationship between ctDNA detection and CA19-9, and the prognostic significance of ctDNA detection were analyzed. RESULTS: 56 patients were included in the analysis. ctDNA was detectable in 48% at diagnosis, 33% post-NAC, and 41% after local therapy. After completion of NAC, patients with detectable ctDNA had higher CA19-9 levels versus those without (78.4 vs. 30.0, P=0.02). The presence of baseline ctDNA was associated with a CA19-9 response; those without ctDNA had a significant CA19-9 response following NAC (109.0 U/mL vs. 31.5 U/mL; P=0.01), while those with ctDNA present at diagnosis did not (198.1 U/mL vs. 113.8 U/mL; P=0.77). In patients treated with NAC, the presence of KRAS ctDNA at diagnosis was associated with and independently predicted worse progression-free-survival. CONCLUSION: This report demonstrates the prognostic value of ctDNA analysis with NGS in localized PDAC. NGS ctDNA is a biomarker of treatment response to NAC. KRAS ctDNA at diagnosis independently predicts worse survival in patients treated with NAC.

Circulating Tumor Cells Prediction in Hormone Receptor Positive HER2-Negative Advanced Breast Cancer: A Retrospective Analysis of the MONARCH 2 Trial.

BACKGROUND: The MONARCH 2 trial (NCT02107703) showed the efficacy of abemaciclib, a cyclin-dependent kinase 4 & 6 inhibitor (CDK4/6i), in combination with fulvestrant for hormone receptor-positive, HER2-negative metastatic breast cancer (MBC). The aim of this analysis was to explore the prediction of circulating tumor cells (CTCs) stratification using machine learning for hypothesis generation of biomarker-driven clinical trials. PATIENTS AND METHODS: Predicted CTCs were computed in the MONARCH 2 trial through a K nearest neighbor (KNN) classifier trained on a dataset comprising 2436 patients with MBC. Patients were categorized into predicted Stage IVaggressive (pStage IVaggressive, ≥5 predicted CTCs) or predicted Stage IVindolent (pStage IVindolent, <5 predicted CTCs). Prognosis was tested in terms of progression-free-survival (PFS) and overall survival (OS) through Cox regression. RESULTS: Patients classified as predicted pStage IVaggressive and predicted pStage Stage IVindolent were, respectively, 183 (28%) and 461 (72%). After multivariable Cox regression, predicted CTCs were confirmed as independently associated with prognosis in terms of OS, together with ECOG performance status, liver involvement, bone-only disease, and treatment arm. Patients in the pStage Stage IVindolent subgroup treated with abemaciclib experienced the best prognosis both in terms of PFS and OS. The treatment effect of abemaciclib on OS was then explored through subgroup analysis, showing a consistent benefit across all subgroups. CONCLUSION: This study is the first analysis of CTCs modeling for stage IV disease stratification. These results show the need to expand biomarker profiling in combination with CTCs stratification for improved biomarker-driven drug development.

Baseline Tumor Size as Prognostic Index in Patients With Advanced Solid Tumors Receiving Experimental Targeted Agents.

BACKGROUND: Baseline tumor size (BTS) has been associated with outcomes in patients with cancer treated with immunotherapy. However, the prognostic impact of BTS on patients receiving targeted therapies (TTs) remains undetermined. METHODS: We reviewed data of patients with advanced solid tumors consecutively treated within early-phase clinical trials at our institution from 01/2014 to 04/2021. Treatments were categorized as immunotherapy-based or TT-based (biomarker-matched or not). BTS was calculated as the sum of RECIST1.1 baseline target lesions. RESULTS: A total of 444 patients were eligible; the median BTS was 69 mm (IQR 40-100). OS was significantly longer for patients with BTS lower versus higher than the median (16.6 vs. 8.2 months, P < .001), including among those receiving immunotherapy (12 vs. 7.5 months, P = .005). Among patients receiving TT, lower BTS was associated with longer PFS (4.7 vs. 3.1 months, P = .002) and OS (20.5 vs. 9.9 months, P < .001) as compared to high BTS. However, such association was only significant among patients receiving biomarker-matched TT, with longer PFS (6.2 vs. 3.3 months, P < .001) and OS (21.2 vs. 6.7 months, P < .001) in the low-BTS subgroup, despite a similar ORR (28% vs. 22%, P = .57). BTS was not prognostic among patients receiving unmatched TT, with similar PFS (3.7 vs. 4.4 months, P = .30), OS (19.3 vs. 11.8 months, P = .20), and ORR (33% vs. 28%, P = .78) in the 2 BTS groups. Multivariate analysis confirmed that BTS was independently associated with PFS (P = .03) and OS (P < .001) but not with ORR (P = .11). CONCLUSIONS: Higher BTS is associated with worse survival outcomes among patients receiving biomarker-matched, but not biomarker-unmatched TT.

Modeling the management of patients with human epidermal growth factor receptor 2-positive breast cancer with liquid biopsy: the future of precision medicine.

PURPOSE OF REVIEW: In the evolving landscape of human epidermal growth factor receptor 2 (HER2)-positive breast cancer (BC) management, liquid biopsy offers unprecedented opportunities for guiding clinical decisions. Here, we review the most recent findings on liquid biopsy applications in HER2-positive BC and its potential role in addressing challenges specific to this BC subtype. RECENT FINDINGS: Recent studies have highlighted the significance of liquid biopsy analytes, primarily circulating tumor DNA (ctDNA) and circulating tumor cells (CTCs), in stratifying patients' prognosis, predicting treatment response, and monitoring tumor evolution in both early and advanced stages of BC. Liquid biopsy holds promise in studying minimal residual disease to detect and potentially treat disease recurrence before it manifests clinically. Additionally, liquid biopsy may have significant implication in the management of brain metastasis, a major challenge in HER2-positive BC, and could redefine parameters for determining HER2 positivity. Combining ctDNA and CTCs is crucial for a comprehensive understanding of HER2-positive tumors, as they provide complementary insights. SUMMARY: Research efforts are needed to address analytical challenges, validate, and broaden the application of liquid biopsy in HER2-positive BC. This effort will ultimately facilitate its integration into clinical practice, optimizing the care of patients with HER2-positive tumors.

Interplay between ESR1/PIK3CA codon variants, oncogenic pathway alterations and clinical phenotype in patients with metastatic breast cancer (MBC): comprehensive circulating tumor DNA (ctDNA) analysis.

BACKGROUND: although being central for the biology and druggability of hormone-receptor positive, HER2 negative metastatic breast cancer (MBC), ESR1 and PIK3CA mutations are simplistically dichotomized as mutated or wild type in current clinical practice. METHODS: The study analyzed a multi-institutional cohort comprising 703 patients with luminal-like MBC characterized for circulating tumor DNA through next generation sequencing (NGS). Pathway classification was defined based on previous work (i.e., RTK, RAS, RAF, MEK, NRF2, ER, WNT, MYC, P53, cell cycle, notch, PI3K). Single nucleotide variations (SNVs) were annotated for their oncogenicity through OncoKB. Only pathogenic variants were included in the models. Associations among clinical characteristics, pathway classification, and ESR1/PIK3CA codon variants were explored. RESULTS: The results showed a differential pattern of associations for ESR1 and PIK3CA codon variants in terms of co-occurring pathway alterations patterns of metastatic dissemination, and prognosis. ESR1 537 was associated with SNVs in the ER and RAF pathways, CNVs in the MYC pathway and bone metastases, while ESR1 538 with SNVs in the cell cycle pathway and liver metastases. PIK3CA 1047 and 542 were associated with CNVs in the PI3K pathway and with bone metastases. CONCLUSIONS: The study demonstrated how ESR1 and PIK3CA codon variants, together with alterations in specific oncogenic pathways, can differentially impact the biology and clinical phenotype of luminal-like MBC. As novel endocrine therapy agents such as selective estrogen receptor degraders (SERDS) and PI3K inhibitors are being developed, these results highlight the pivotal role of ctDNA NGS to describe tumor evolution and optimize clinical decision making.

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).

Design of SERENA-6, a phase III switching trial of camizestrant in ESR1-mutant breast cancer during first-line treatment.

ESR1 mutation (ESR1m) is a frequent cause of acquired resistance to aromatase inhibitor (AI) plus cyclin-dependent kinase 4 and 6 inhibitors (CDK4/6i), which is a first-line therapy for hormone-receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC). Camizestrant is a next-generation oral selective estrogen receptor degrader (SERD) that in a phase II study significantly improved progression-free survival (PFS) over fulvestrant (also a SERD) in ER+/HER2- ABC. SERENA-6 (NCT04964934) is a randomized, double-blind, phase III study evaluating the efficacy and safety of switching from an AI to camizestrant, while maintaining the same CDK4/6i, upon detection of ESR1m in circulating tumor DNA before clinical disease progression on first-line therapy for HR+/HER2- ABC. The aim is to treat ESR1m clones and extend the duration of control of ER-driven tumor growth, delaying the need for chemotherapy. The primary end point is PFS; secondary end points include chemotherapy-free survival, time to second progression event (PFS2), overall survival, patient-reported outcomes and safety.

Why will we perform this study? Patients with advanced breast cancer in which the cancer cells have the receptor for the hormone estrogen and/or progesterone are typically treated with an aromatase inhibitor, a hormone therapy that decreases estrogen being made in the body, together with an inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), a drug that blocks the growth of cancer cells. Although cancers usually respond to treatment initially, the cancer cells eventually change, so the drug combination no longer works. For example, mutation of the estrogen receptor (referred to as ESR1m) can stop aromatase inhibitors from working. Camizestrant is an investigational drug that blocks estrogen receptors, including mutated receptors, reducing the growth and spread of cancer. Here we describe the SERENA-6 clinical trial, which is testing camizestrant as a treatment for patients with breast cancer with ESR1m. How will we perform this research? The phase III SERENA-6 trial will use blood tests to monitor if patients with breast cancer develop ESR1m while being treated with an aromatase inhibitor and a CDK4/6 inhibitor. If ESR1m is detected, yet the disease is stable, participants will be randomly assigned to either continue with the same aromatase inhibitor or switch to camizestrant while continuing with the same CDK4/6 inhibitor. The study will assess whether switching to camizestrant prolongs the time before the cancer grows, spreads or worsens. It will also assess the length of time that participants live for versus those who continue with an aromatase inhibitor. Clinical Trial Registration: NCT04964934 (ClinicalTrials.gov).

CCR5 activation and endocytosis in circulating tumor-derived cells isolated from the blood of breast cancer patients provide information about clinical outcome.

BACKGROUND: CCR5 is a motility chemokine receptor implicated in tumor progression, whose activation and subsequent endocytosis may identify highly aggressive breast cancer cell subtypes likely to spread into the circulatory system. METHODS: The MDA-MB-231 cell line was used to model and visualize CCR5 activation by stimulation with RANTES, in an effort to quantify CCR5 endocytosis from the cell surface to the perinuclear space. CCR5 expression was then examined in tumor-associated cells (TACs), consisting of circulating tumor cells and circulating stromal cells, isolated from the peripheral blood of 54 metastatic breast cancer (mBC) patients to evaluate these CCR5 pooling patterns as they relate to progression and survival over 2 years. RESULTS: In MB231 experiments, it was observed that CCR5 formed ~ 1 micron clusters identified as "CCR5 pools" on the surface of the cell, which in the presence of RANTES were endocytosed and translocated to the cell cytoplasm. When TACs from patients were analyzed, CCR5 pools were observed on the cell surface and translocating to the nuclear area, with CCR5 also having a positive statistical correlation between increased numbers of TACs and increased CCR5 pools on the cells. Further, it was determined that patients with very high numbers of CCR5 (> 10 CCR5 pools), specifically in the circulating stromal cells, were associated with worse progression-free survival (hazard ratio = 4.5, p = 0.002) and worse overall survival (hazard ratio = 3.7, p = 0.014). CONCLUSIONS: Using a liquid biopsy approach, we evaluated two populations of tumor-associated cells emanating from primary tumors, with data suggesting that upregulation of the motility chemokine CCR5 in TACs provides clinically relevant opportunities for treating and tracking drug targetable receptors in mBC.

Circulating tumour cells in the -omics era: how far are we from achieving the 'singularity'?

Over the past decade, cancer diagnosis has expanded to include liquid biopsies in addition to tissue biopsies. Liquid biopsies can result in earlier and more accurate diagnosis and more effective monitoring of disease progression than tissue biopsies as samples can be collected frequently. Because of these advantages, liquid biopsies are now used extensively in clinical care. Liquid biopsy samples are analysed for circulating tumour cells (CTCs), cell-free DNA, RNA, proteins and exosomes. CTCs originate from the tumour, play crucial roles in metastasis and carry information on tumour heterogeneity. Multiple single-cell omics approaches allow the characterisation of the molecular makeup of CTCs. It has become evident that CTCs are robust biomarkers for predicting therapy response, clinical development of metastasis and disease progression. This review describes CTC biology, molecular heterogeneity within CTCs and the involvement of EMT in CTC dynamics. In addition, we describe the single-cell multi-omics technologies that have provided insights into the molecular features within therapy-resistant and metastasis-prone CTC populations. Functional studies coupled with integrated multi-omics analyses have the potential to identify therapies that can intervene the functions of CTCs.

Modeling the Prognostic Impact of Circulating Tumor Cells Enumeration in Metastatic Breast Cancer for Clinical Trial Design Simulation.

Despite the strong prognostic stratification of circulating tumor cells (CTCs) enumeration in metastatic breast cancer (MBC), current clinical trials usually do not include a baseline CTCs in their design. This study aimed to generate a classifier for CTCs prognostic simulation in existing datasets for hypothesis generation in patients with MBC. A K-nearest neighbor machine learning algorithm was trained on a pooled dataset comprising 2436 individual MBC patients from the European Pooled Analysis Consortium and the MD Anderson Cancer Center to identify patients likely to have CTCs ≥ 5/7 mL blood (StageIVaggressive vs StageIVindolent). The model had a 65.1% accuracy and its prognostic impact resulted in a hazard ratio (HR) of 1.89 (Simulatedaggressive vs SimulatedindolentP < .001), similar to patients with actual CTCs enumeration (HR 2.76; P < .001). The classifier's performance was then tested on an independent retrospective database comprising 446 consecutive hormone receptor (HR)-positive HER2-negative MBC patients. The model further stratified clinical subgroups usually considered prognostically homogeneous such as patients with bone-only or liver metastases. Bone-only disease classified as Simulatedaggressive had a significantly worse overall survival (OS; P < .0001), while patients with liver metastases classified as Simulatedindolent had a significantly better prognosis (P < .0001). Consistent results were observed for patients who had undergone CTCs enumeration in the pooled population. The differential prognostic impact of endocrine- (ET) and chemotherapy (CT) was explored across the simulated subgroups. No significant differences were observed between ET and CT in the overall population, both in terms of progression-free survival (PFS) and OS. In contrast, a statistically significant difference, favoring CT over ET was observed among Simulatedaggressive patients (HR: 0.62; P = .030 and HR: 0.60; P = .037, respectively, for PFS and OS).

Leptomeningeal metastases: the future is now.

Leptomeningeal metastases (LM) constitute an involvement of cancer which is associated with marked morbidity and mortality. The contemporary diagnostic and therapeutic management of LM from solid tumors is reviewed. Therapeutic modalities including systemic therapies, cerebrospinal fluid (CSF)-directed therapies, and radiation therapy are discussed. This is to provide context for how the field of LM management may evolve in the near term. The future directions currently undergoing investigation for diagnostic, response assessment, and therapeutic purposes are highlighted. This is done within the context of the pathophysiology of the disease. Specifically the role of CSF circulating tumor cells and cell free circulating tumor DNA in diagnosis and response assement are reviewed. Novel therapeutic approaches across a range of modalities are discussed. Numerous ongoing studies which have the potential to alter the management of LM are referenced.

Beta 2-Adrenergic Receptor in Circulating Cancer-Associated Cells Predicts for Increases in Stromal Macrophages in Circulation and Patient Survival in Metastatic Breast Cancer.

The usage of beta blockers in breast cancer (BC) patients is implicated in the reduction in distant metastases, cancer recurrence, and cancer mortality. Studies suggest that the adrenergic pathway is directly involved in sympathetic-driven hematopoietic activation of pro-tumor microenvironmental proliferation and tumor cell trafficking into the circulation. Cancer-associated macrophage-like cells (CAMLs) are pro-tumor polynucleated monocytic cells of hematopoietic origin emanating from tumors which may aid in circulating tumor cell (CTC) dissemination into the circulation. We examined the linkage between Beta-2 adrenergic receptor (B2AR) signaling in CAMLs and CTCs by establishing expression profiles in a model BC cell line (MDA-MB-231). We compared the model to CAMLs and CTCs found in patents. Although internalization events were observed in patients, differences were found in the expression of B2AR between the tumor cell lines and the CAMLs found in patients. High B2AR expression on patients' CAMLs was correlated with significantly more CAMLs in the circulation (p = 0.0093), but CTCs had no numerical relationship (p = 0.1565). High B2AR CAML expression was also significantly associated with a larger size of CAMLs (p = 0.0073), as well as being significantly associated with shorter progression-free survival (p = 0.0097) and overall survival (p = 0.0265). These data suggest that B2AR expression on CAMLs is closely related to the activation, intravasation, and growth of CAMLs in the circulation.

The curious phenomenon of dual-positive circulating cells: Longtime overlooked tumor cells.

The presence in the blood of patients with solid tumors of circulating cells expressing both epithelial and leukocyte markers (dual-positive cells, DPcells), has often been reported, though it has never been investigated in detail. A recent study suggested that DPcells are hybrid cells derived from the fusion of tumor cells with macrophages. Such fusion hybrids acquire macrophage-associated features endowing them with accelerated growth, increased motility, enhanced invasion activity and thus, a higher efficiency in metastasis formation. However, no direct evidence proving the tumor origin of circulating DPcells was provided in patients. Here we contribute a review of literature data on DPcells and on the hybrid theory with the aim of putting the current evidence both in a biological and clinical perspective and to generate new hypotheses on the mechanisms underlying tumor progression. To add further biological and clinical context to our literature review, we also report some preliminary data from our laboratory on the identification of DPcells in several solid tumors and confirmation of their malignant genotype, thus classifying them as DP-CTCs.

Comparative effectiveness of first-line palbociclib plus letrozole versus letrozole alone for HR+/HER2- metastatic breast cancer in US real-world clinical practice.

BACKGROUND: Findings from randomized clinical trials may have limited generalizability to patients treated in routine clinical practice. This study examined the effectiveness of first-line palbociclib plus letrozole versus letrozole alone on survival outcomes in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor-negative (HER2-) metastatic breast cancer (MBC) treated in routine clinical practice in the USA. PATIENTS AND METHODS: This was a retrospective observational analysis of electronic health records within the Flatiron Health Analytic Database. A total of 1430 patients with ≥ 3 months of follow-up received palbociclib plus letrozole or letrozole alone in the first-line setting between February 3, 2015, and February 28, 2019. Stabilized inverse probability treatment weighting (sIPTW) was used to balance baseline demographic and clinical characteristics. Real-world progression-free survival (rwPFS) and overall survival (OS) were analyzed. RESULTS: After sIPTW adjustment, median follow-up was 24.2 months (interquartile range [IQR], 14.2-34.9) in the palbociclib group and 23.3 months (IQR, 12.7-34.3) in those taking letrozole alone. Palbociclib combination treatment was associated with significantly longer median rwPFS compared to letrozole alone (20.0 vs 11.9 months; hazard ratio [HR], 0.58; 95% CI, 0.49-0.69; P < 0.0001). Median OS was not reached in the palbociclib group and was 43.1 months with letrozole alone (HR, 0.66; 95% CI, 0.53-0.82; P = 0.0002). The 2-year OS rate was 78.3% in the palbociclib group and 68.0% with letrozole alone. A propensity score matching analysis showed similar results. CONCLUSIONS: In this "real-world" population of patients with HR+/HER2- MBC, palbociclib in combination with endocrine therapy was associated with improved survival outcomes compared with patients treated with letrozole alone in the first-line setting. TRIAL REGISTRATION: Clinicaltrials.gov; NCT04176354.

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.

Long-Term Pooled Safety Analysis of Palbociclib in Combination with Endocrine Therapy for Hormone Receptor-Positive/Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Updated Analysis with up to 5 Years of Follow-Up.

BACKGROUND: Previous studies demonstrated the tolerability of palbociclib plus endocrine therapy (ET). This analysis evaluated safety based on more recent cutoff dates and a longer palbociclib treatment exposure. PATIENTS AND METHODS: Data were pooled from three randomized studies of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC), including postmenopausal women who had not received prior systemic treatment for advanced disease (PALOMA-1/-2) and pre- and postmenopausal women who had progressed on prior ET (PALOMA-3). RESULTS: Updated cutoff dates were December 21, 2017 (PALOMA-1), May 31, 2017 (PALOMA-2), and April 13, 2018 (PALOMA-3). Total person-years of treatment exposure were 1,421.6 with palbociclib plus ET (n = 872) and 528.4 with ET (n = 471). Any-grade neutropenia and infections were more frequent with palbociclib plus ET (82.1% and 59.2%, respectively) than with ET (5.1% and 39.5%). The hazard ratios were 1.6 (p = .0995) for grade 3/4 infections, 1.8 (p = .4358) for grade 3/4 viral infections, 1.4 (p = .0001) for infections, and 30.8 (p < .0001) for neutropenia. Febrile neutropenia was reported in 1.4% of patients receiving palbociclib plus ET. Cumulative incidence of all-grade hematologic adverse events in both arms peaked during the first year of treatment and plateaued over the 5 subsequent years. Interstitial lung disease was reported in 13 patients receiving palbociclib plus ET and 3 receiving ET. CONCLUSION: This 5-year, long-term analysis demonstrated that palbociclib plus ET has a consistent and stable safety profile and is a safe treatment for patients with HR+/HER2- ABC. IMPLICATIONS FOR PRACTICE: Several treatments for patients with breast cancer are associated with long-term or latent adverse events. This long-term, 5-year analysis demonstrated that palbociclib plus endocrine therapy has a consistent and stable safety profile without cumulative or delayed toxicities. These results further support palbociclib plus endocrine therapy as a safe and manageable treatment in clinical practice for patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer.

Evaluation of the Association of Polymorphisms With Palbociclib-Induced Neutropenia: Pharmacogenetic Analysis of PALOMA-2/-3.

BACKGROUND: The most frequently reported treatment-related adverse event in clinical trials with the cyclin-dependent kinase 4/6 (CDK4/6) inhibitor palbociclib is neutropenia. Allelic variants in ABCB1 and ERCC1 might be associated with early occurrence (i.e., end of week 2 treatment) of grade 3/4 neutropenia. Pharmacogenetic analyses were performed to uncover associations between single nucleotide polymorphisms (SNPs) in these genes, patient baseline characteristics, and early occurrence of grade 3/4 neutropenia. MATERIALS AND METHODS: ABCB1 (rs1045642, rs1128503) and ERCC1 (rs3212986, rs11615) were analyzed in germline DNA from palbociclib-treated patients from PALOMA-2 (n = 584) and PALOMA-3 (n = 442). SNP, race, and cycle 1 day 15 (C1D15) absolute neutrophil count (ANC) data were available for 652 patients. Univariate and multivariable analyses evaluated associations between SNPs, patient baseline characteristics, and early occurrence of grade 3/4 neutropenia. Analyses were stratified by Asian (n = 122) and non-Asian (n = 530) ethnicity. Median progression-free survival (mPFS) was estimated using the Kaplan-Meier method. The effect of genetic variants on palbociclib pharmacokinetics was analyzed. RESULTS: ABCB1 and ERCC1_rs11615 SNP frequencies differed between Asian and non-Asian patients. Multivariable analysis showed that low baseline ANC was a strong independent risk factor for C1D15 grade 3/4 neutropenia regardless of race (Asians: odds ratio [OR], 6.033, 95% confidence interval [CI], 2.615-13.922, p < .0001; Non-Asians: OR, 6.884, 95% CI, 4.138-11.451, p < .0001). ABCB1_rs1128503 (C/C vs. T/T: OR, 0.57, 95% CI, 0.311-1.047, p = .070) and ERCC1_rs11615 (A/A vs. G/G: OR, 1.75, 95% CI, 0.901-3.397, p = .098) were potential independent risk factors for C1D15 grade 3/4 neutropenia in non-Asian patients. Palbociclib mPFS was consistent across genetic variants; exposure was not associated with ABCB1 genotype. CONCLUSION: This is the first comprehensive assessment of pharmacogenetic data in relationship to exposure to a CDK4/6 inhibitor. Pharmacogenetic testing may inform about potentially increased likelihood of patients developing severe neutropenia (NCT01740427, NCT01942135). IMPLICATIONS FOR PRACTICE: Palbociclib plus endocrine therapy improves hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer outcomes, but is commonly associated with neutropenia. Genetic variants in ABCB1 may influence palbociclib exposure, and in ERCC1 are associated with chemotherapy-induced severe neutropenia. Here, the associations of single nucleotide polymorphisms in these genes and baseline characteristics with neutropenia were assessed. Low baseline absolute neutrophil count was a strong risk factor (p < .0001) for grade 3/4 neutropenia. There was a trend indicating that ABCB1_rs1128503 and ERCC1_rs11615 were potential risk factors (p < .10) for grade 3/4 neutropenia in non-Asian patients. Pharmacogenetic testing could inform clinicians about the likelihood of severe neutropenia with palbociclib.

Overall Survival with Palbociclib and Fulvestrant in Advanced Breast Cancer.

BACKGROUND: The cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor palbociclib, in combination with fulvestrant therapy, prolongs progression-free survival among patients with hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. We report the results of a prespecified analysis of overall survival. METHODS: We randomly assigned patients with hormone-receptor-positive, HER2-negative advanced breast cancer who had progression or relapse during previous endocrine therapy to receive palbociclib plus fulvestrant or placebo plus fulvestrant. We analyzed overall survival; the effect of palbociclib according to the prespecified stratification factors of presence or absence of sensitivity to endocrine therapy, presence or absence of visceral metastatic disease, and menopausal status; the efficacy of subsequent therapies after disease progression; and safety. RESULTS: Among 521 patients who underwent randomization, the median overall survival was 34.9 months (95% confidence interval [CI], 28.8 to 40.0) in the palbociclib-fulvestrant group and 28.0 months (95% CI, 23.6 to 34.6) in the placebo-fulvestrant group (hazard ratio for death, 0.81; 95% CI, 0.64 to 1.03; P=0.09; absolute difference, 6.9 months). CDK4/6 inhibitor treatment after the completion of the trial regimen occurred in 16% of the patients in the placebo-fulvestrant group. Among 410 patients with sensitivity to previous endocrine therapy, the median overall survival was 39.7 months (95% CI, 34.8 to 45.7) in the palbociclib-fulvestrant group and 29.7 months (95% CI, 23.8 to 37.9) in the placebo-fulvestrant group (hazard ratio, 0.72; 95% CI, 0.55 to 0.94; absolute difference, 10.0 months). The median duration of subsequent therapy was similar in the two groups, and the median time to the receipt of chemotherapy was 17.6 months in the palbociclib-fulvestrant group, as compared with 8.8 months in the placebo-fulvestrant group (hazard ratio, 0.58; 95% CI, 0.47 to 0.73; P<0.001). No new safety signals were observed with 44.8 months of follow-up. CONCLUSIONS: Among patients with hormone-receptor-positive, HER2-negative advanced breast cancer who had sensitivity to previous endocrine therapy, treatment with palbociclib-fulvestrant resulted in longer overall survival than treatment with placebo-fulvestrant. The differences in overall survival in the entire trial group were not significant. (Funded by Pfizer; PALOMA-3 ClinicalTrials.gov number, NCT01942135 .).

Circulating tumor cells, circulating tumor DNA, and disease characteristics in young women with metastatic breast cancer.

BACKGROUND: Clinical and genomic data from patients with early-stage breast cancer suggest more aggressive disease in premenopausal women. However, the association between age, disease course, and molecular profile from liquid biopsy in metastatic breast cancer (MBC) is not well characterized. METHODS: Patients were classified as premenopausal (< 45 years), perimenopausal (45-55 years), or postmenopausal (> 55 years). Cohort 1 consisted of patients with MBC who consented for prospective serial evaluation of circulating tumor cells (CTCs) using CellSearch™. Cohort 2 included patients who, as part of routine care, had circulating tumor DNA (ctDNA) sequenced by the Guardant360™ assay. Clinicopathologic data were collected from retrospective review to compare disease features between premenopausal and postmenopausal women. RESULTS: Premenopausal women represented 26% of 138 patients in Cohort 1 and 21% of 253 patients in Cohort 2. In Cohort 1, younger patients had a shorter time to metastases and a higher prevalence of lung and brain metastases. Overall, there were similar rates of ≥ 5 CTCs/7.5 mL, HER2 + CTC expression, and CTC clusters between pre- and postmenopausal women. However, for those with triple negative breast cancer, premenopausal women had a higher proportion of ≥ 5 CTCs/7.5 mL. In Cohort 2, premenopausal women had a higher incidence of FGFR1 (OR 2.75, p = 0.022) and CCND2 (OR 6.91, p = 0.024) alterations. There was no difference in the ctDNA mutant allele frequency or the number of detected alterations between these age groups. CONCLUSIONS: Our data reveal that premenopausal women diagnosed with MBC have unique clinical, pathologic, and molecular features when compared to their postmenopausal counterparts. Our results highlight FGFR1 inhibitors as potential therapeutics of particular interest among premenopausal women.

Cell-free DNA comparative analysis of the genomic landscape of first-line hormone receptor-positive metastatic breast cancer from the US and China.

PURPOSE: Meaningful comparison of mutational landscapes across ethnic groups requires the use of standardized platform technology. We have used a harmonized NGS-based liquid biopsy assay to explore the differential genomic landscape of patients with initially hormone receptor-positive (HR+), HER2-negative MBC of first line metastasis or primary Stage IV at diagnosis from the United States (US) and China (CN). METHODS: Plasma circulating tumor DNA (ctDNA) from 27 US patients and 65 CN patients was sequenced using the harmonized CLIA-certified, 152-gene PredicineCare™ liquid biopsy assay. Kaplan-Meier survival analysis was performed to analyze the correlation between genomic alterations and progression-free survival (PFS), and p-values were calculated using the log-rank test. RESULTS: All patients in the CN cohort received chemotherapy and/or hormonal therapy, while 85.2% (23/27) patients in the US cohort received hormonal therapy plus CDK4/6 inhibitors. Mutations were detected in 23 of 27 (85%) US patients and 54 of 65 (83%) CN patients. The prevalence of AKT1 (P = 0.008) and CDH1 (P = 0.021) alterations were both higher in the US vs. CN cohort. In addition, FGFR1 amplification were more frequent in the CN vs. US cohort (P = 0.048). PTEN deletions (P = 0.03) and ESR1 alterations (P = 0.02) were associated with shorter PFS in the CN cohort, neither of these associations were observed in the US cohort. Interestingly, a reduced association between PTEN deletion and PFS was observed in patients receiving CDK4/6 inhibitor treatment. CONCLUSION: The differential prevalence of ctDNA-based alterations such as FGFR1, AKT1, and CDH1 was observed in initially HR+/HER2- MBC patients in the US vs. CN. In addition, the association of PTEN deletions with shorter PFS was found in the CN but not the US cohort. The differential genomic landscapes across the two ethnic groups may reflect biologic differences and clinical implications.