Pharmacokinetics of eribulin mesylate in patients with solid tumors and hepatic impairment

Prospective Challenges for Patenting and Clinical Trials of Anticancer Compounds from Natural Products: Coherent Review

Cancer is a leading cause of morbidity and mortality worldwide. Each year, millions of people worldwide are diagnosed with cancer, and more than half of them die. Various conventional therapies for cancer, including chemotherapy and radiotherapy, have extreme side effects. Therefore, to minimize the global burden of lethal diseases like cancer, an effective and novel drug must be discovered. Its patent should be acquired to secure the novel medicament. The pharmacological potential of different natural products has made them popular in the healthcare and pharmaceutical industries. Various anticancer compounds are obtained from natural sources such as plants, microbes, and marine and terrestrial animals, including alkaloids, terpenoids, biophenols, enzymes, glycosides, etc. The term "natural products" is defined as the product of secondary or non-essential metabolic processes produced by living organisms (such as plants, invertebrates, and microorganisms). Although more precise definitions of NPs exist, they do not always meet consensus. Others define NPs as small molecules (excluding biomolecules) that emerge from the metabolic reaction. A handful of effective compounds are used currently from natural or analog moieties, and many more are in clinical studies. There is an excellent need for patenting molecules from natural products as the hit lead molecules are derived, isolated, and synthesized from natural products. However, these naturally occurring products may not be patentable under the law because they come from nature. This review highlights why natural products and compounds are hard to patent, under what patent law criteria we can patent these natural products and compounds, patent procedural guideline sources and why researchers prefer publication rather than a patent. Here, various patent scenarios of natural products and compounds for cancer have been given.

Optimization of G-CSF dosing schedule in patients treated with eribulin: a modeling approach

BACKGROUND

Granulocyte colony-stimulating factors (G-CSF) are commonly given to limit chemotherapy-induced neutropenia, but, in case of weekly chemotherapy such as eribulin, their administration schedules remain empirical.

OBJECTIVES

This pharmacokinetic/pharmacodynamic (PK/PD) study was conducted to establish the effect of different G-CSF regimens on neutropenia's incidence for patients treated by eribulin, to propose an optimal G-CSF dosing schedule.

METHODS

A population PK/PD model was developed to describe absolute neutrophil counts' (ANC) time course in 87 cancer patients receiving eribulin. The structural model considered ANC dynamics, neutropenic effect of eribulin and stimulating effect of G-CSF. Final model estimates were used to calculate neutropenia's incidence following different G-CSF dosing schedules for 1000 virtual subjects.

RESULTS

The final model successfully described most of the ANC time course for all patients. Simulations showed that a single G-CSF administration 48 h after each eribulin injection reduced the risk of severe neutropenia from 29.7 to 5.2%. Five days of G-CSF only after the second eribulin injection or no G-CSF administration induces similar incidence of neutropenia.

CONCLUSION

Simulations showed a single G-CSF administration 48 h after the end of each eribulin injection seems to be the optimal schedule to reduce eribulin-induced neutropenia. However, the new administration scheme should be tested in real life to evaluate its pertinence.

TRIAL REGISTRATION

Eudract 2015-001753-32, 2015/01/26.

Chemotherapy, targeted therapy and immunotherapy: Which drugs can be safely used in the solid organ transplant recipients?

In solid organ transplant recipients, cancer is associated with worse prognosis than in the general population. Among the causes of increased cancer‐associated mortality, are the limitations in selecting the optimal anticancer regimen in solid organ transplant recipients, because of the associated risks of graft toxicity and rejection, drug‐to‐drug interactions, reduced kidney or liver function, and patient frailty and comorbid conditions. The advent of immunotherapy has generated further challenges, mainly because checkpoint inhibitors increase the risk of rejection, which may have life‐threatening consequences in recipients of life‐saving organs. In general, there are no safe or unsafe anticancer drugs. Rather, the optimal choice of the anticancer regimen results from a careful risk/benefit assessment, from the awareness of potential pharmacokinetic and pharmacodynamic drug‐to‐drug interactions, and of the risk of drug overexposure in patients with kidney or liver dysfunction. In this review, we summarize general principles that may help the oncologists and transplant physicians in the multidisciplinary management of recipients of solid organ transplantation with cancer who are candidates for chemotherapy, targeted therapy, or immunotherapy.

Pharmacokinetics and safety of rucaparib in patients with advanced solid tumors and hepatic impairment

PURPOSE

The poly(ADP-ribose) polymerase inhibitor rucaparib is approved for the treatment of patients with recurrent ovarian and metastatic castration-resistant prostate cancer; however, limited data are available on its use in patients with hepatic dysfunction. This study investigated whether hepatic impairment affects the pharmacokinetics, safety, and tolerability of rucaparib in patients with advanced solid tumors.

METHODS

Patients with normal hepatic function or moderate hepatic impairment according to the National Cancer Institute Organ Dysfunction Working Group (NCI-ODWG) criteria were enrolled and received a single oral dose of rucaparib 600 mg. Concentrations of rucaparib and its metabolite M324 in plasma and urine were measured. Pharmacokinetic parameters were compared between hepatic function groups, and safety and tolerability were assessed.

RESULTS

Sixteen patients were enrolled (n = 8 per group). Rucaparib maximum concentration (Cmax) was similar, while the area under the concentration-time curve from time 0 to infinity (AUC0-inf) was mildly higher in the moderate hepatic impairment group than in the normal control group (geometric mean ratio, 1.446 [90% CI 0.668-3.131]); similar trends were observed for M324. Eight (50%) patients experienced ≥ 1 treatment-emergent adverse event (TEAE); 2 had normal hepatic function and 6 had moderate hepatic impairment.

CONCLUSION

Patients with moderate hepatic impairment showed mildly increased AUC0-inf for rucaparib compared to patients with normal hepatic function. Although more patients with moderate hepatic impairment experienced TEAEs, only 2 TEAEs were considered treatment related. These results suggest no starting dose adjustment is necessary for patients with moderate hepatic impairment; however, close safety monitoring is warranted.

Eribulin, Child-Pugh score, and liver-function tests: lessons from pivotal breast cancer studies 301 and 305

Background

The recommended starting dose of eribulin in patients with hepatic impairment is based on the Child-Pugh score, largely informed by a pharmacokinetic study of 18 patients. In the pivotal studies of eribulin in metastatic breast cancer (Study 301 and Study 305 [EMBRACE]), entry criteria and dose modifications were based on liver-function test (LFT) results rather than Child-Pugh score. In populations such as patients with metastatic breast cancer, in which metastatic infiltration is the predominant cause of hepatic impairment, using Child-Pugh score may be problematic; in clinical practice, it has been more common for oncologists to make dosing decisions based on LFTs. To address this, the effects of abnormal baseline LFT results on eribulin efficacy and safety were investigated.

Methods

In this pooled post hoc analysis, 1062 patients who were randomized to receive eribulin in Studies 301 and 305 were divided into 4 groups: (A) no elevated LFT results (no liver impairment); (B) increased levels of aspartate aminotransferase and/or alanine aminotransferase; (C) decreased albumin and/or increased levels of aspartate aminotransferase and/or alanine aminotransferase but not increased bilirubin; and (D) increased bilirubin. Patients were subcategorized by presence of liver metastasis. Drug exposure, dose intensity, and treatment-emergent adverse events (TEAEs) were analyzed.

Results

Eribulin mesylate mean dosage was 0.82 (group A)–0.65 mg/m²/week (group D). Group D had shorter treatment, more dose reductions/delays, more TEAEs leading to dose modifications, and numerically lower objective response rates and clinical benefit rates versus groups A–C. TEAE rates leading to dose modification were similar between group D (45.5%) and groups A–C (range, 43.5–54.9%) in the absence of liver metastases, but higher in group D (91.3%) compared with groups A–C (range, 41.7–54.3%) if liver metastases were present.

Conclusions

Mild elevations in bilirubin levels were associated with increased toxicity and a greater requirement for dose modifications. Based both on these study data and existing recommendations, we propose a novel scheme to guide initial dose selection in patients with metastatic breast cancer and hepatic impairment that is based on LFTs rather than Child-Pugh score.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01407-w.

Effect of renal function on neutrophil decreases following eribulin administration

BACKGROUND

Eribulin therapy has recently attracted attention from various viewpoints, including quality of life, and is considered a standard therapy for inoperable or recurrent breast cancer. Although a reduction in renal function reportedly decreases total eribulin clearance, its association with dose-limiting toxicity and the reduction of neutrophils remain unclear.

AIM

This study was aimed at analyzing the association between decreased renal function prior to eribulin administration and the occurrence of neutrophil reduction and time to treatment failure in patients with breast cancer.

METHODS AND RESULTS

We retrospectively assessed patients with breast cancer, who underwent eribulin therapy between July 2011 and March 2018. Multivariate analysis revealed creatinine clearance <70 mL/min and serum albumin levels <3.9 mg/dL as predictive factors for neutrophil reduction. Even on increasing the relative dose intensity by these factors, no difference in time to treatment failure was observed, suggesting that treatment efficacy is potentially unaffected.

CONCLUSIONS

For continuous eribulin therapy, eribulin may need to be administered to individual patients in accordance with renal function and albumin levels before treatment initiation.

Incidence of peripheral neuropathy associated with eribulin mesylate versus vinorelbine in patients with metastatic breast cancer: sub-group analysis of a randomized phase III study

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most significant neurologic complications of chemotherapy, impacting patient's behavior and quality of life. CIPN is mostly sensory, with rare incidences of autonomic dysfunction and other neuropathy.

METHODS

We conducted a single-center sub-group analysis of patients with metastatic breast cancer enrolled in a phase III study (NCT02225470) set up to compare eribulin mesylate (1.4 mg/m² on days 1 and 8 every 21 days) with vinorelbine (25 mg/m² on days 1, 8, and 15 every 21 days). The analysis investigated incidence of peripheral neuropathy, time to onset of neuropathy, and safety.

RESULTS

Our analysis included 110 women with a mean age of 50.7 (SD = 10.9). The median accumulated dose of eribulin was 11.2 mg/m² and 125.0 mg/m² for vinorelbine. Among patients in the eribulin group, a performance status (ECOG PS) of 2 was correlated with peripheral sensory neuropathy (p = 0.015), and accumulated eribulin dose (≥ 10 mg/m²) was associated with all neuropathy and peripheral sensory neuropathy (p = 0.003 and p = 0.007, respectively). In the vinorelbine group, patient age (≥ 65 years) was positively associated with all neuropathy (p = 0.043). The time to onset of neuropathy appeared to be longer for eribulin versus vinorelbine (35.3 vs. 34.6 weeks; p = 0.046), with a significantly higher incidence of autonomic neuropathy at weeks 2 and 10 observed among patients receiving vinorelbine (p = 0.008 and p = 0.043, respectively).

CONCLUSION

Vinorelbine is associated with a higher incidence of autonomic neuropathy than eribulin in patients with metastatic breast cancer. Furthermore, the onset of neurotoxicity appears to occur earlier with vinorelbine than eribulin.

The safety of eribulin for the treatment of metastatic breast cancer

Introduction: Eribulin mesylate is a highly potent anticancer agent approved for use in pretreated metastatic breast cancer (MBC). Clinical trials of eribulin in MBC have demonstrated activity against this tumor type, and a phase 3 study in patients with MBC previously treated with an anthracycline and a taxane showed a significant increase in overall survival (OS) with eribulin versus control regimens. Areas covered: This review presents overviews of the development of eribulin, its pharmacology, and its efficacy in MBC. A detailed review of its safety profile is presented, and the safety of eribulin is compared with other agents commonly used to treat MBC. Expert opinion: As eribulin is the only drug shown to improve OS in patients with pretreated MBC, it is an important treatment option for many patients. Eribulin is currently considered a second-line (Europe) or third-line (United States) therapy, and studies have been examining use in the first-line setting. The use of eribulin in combination with other therapies is beginning to be explored because its manageable safety profile makes it an ideal combination-treatment partner. Emerging eribulin combination-treatment data suggest a manageable toxicity profile, and eribulin is set to be a key drug for the treatment of MBC in the future.

Perspectives on the mechanism of action and clinical application of eribulin for metastatic breast cancer

Eribulin is a novel microtubule inhibitor with mitotic and nonmitotic mechanisms of action. Both pooled and subgroup analyses from large-scale Phase III clinical trials demonstrated that eribulin has substantial activity in patients with pretreated (anthracycline and a taxane) advanced or metastatic breast cancer. We review recent pharmacological and clinical findings pertaining to eribulin use in metastatic breast cancer – particularly highlighting eribulin in difficult-to-treat and aggressive disease, and safety data in specific patient populations. Additionally, recent advancements in our understanding of the mechanism of action of eribulin and potential future directions for its clinical development are discussed. Ongoing studies of eribulin in combination with immunotherapies and established cytotoxic agents may help shape the future landscape of breast cancer treatment.

Eribulin Treatment in Patients with Liver Metastatic Breast Cancer: Eight Italian Case Reports

Liver metastases are very common in metastatic breast cancer (MBC); current treatments for these lesions are based on systemic chemotherapy, endocrine- or human epidermal growth factor receptor 2 (HER2)-targeted therapy, and palliative therapy. However, no standard approach has been clearly identified for second and further chemotherapy lines in MBC patients. In the phase III clinical trial EMBRACE, eribulin was particularly effective in reducing liver lesions and improving both overall survival and progression-free survival in liver MBC patients. In this series, we collected 8 case reports of Italian clinical practice in which eribulin has shown significant efficacy in reducing liver metastases in MBC patients: complete response was reported in 2 patients, and 4 patients achieved partial response. The treatment was well tolerated, thus confirming that eribulin is a suitable therapeutic option for elderly patients and for those who have metastatic HER2-negative disease. In the setting of MBC, the sequencing of therapeutic agents should consider expected response, side effects, tumor characteristics, and patient's preferences, in order to successfully tailor the most appropriate therapy beyond earlier lines.

Experience with eribulin in patients with metastatic breast cancer and associated hepatic impairment: case studies

Hepatic impairment in breast cancer arises from metastatic spread of tumor cells to the liver and signals a poor prognosis. Systemic therapy is the mainstay of treatment. Three women with hepatic dysfunction secondary to breast cancer who were treated with eribulin are presented herein. In the first case, third-line eribulin at the time of acute liver failure due to metastases maintained response for up to 9 months with good tolerability. In the second case, a woman with secondary bone and liver disease had progression-free survival of 5 months to third-line eribulin and, upon rechallenge after a drug holiday, had almost four more months of stable disease. Last, a heavily pretreated patient with secondary bone and hepatic involvement showed a response to fourth-line eribulin.

Eribulin therapy for the treatment of patients with advanced soft tissue sarcoma

Eribulin is a structurally simplified, synthetic macrocyclic ketone analog of halichondrin B, which is a natural, polyether macrolide derived from marine sponges. Eribulin exerts its cytotoxicity by its unique microtubule dynamics inhibitory action. Eribulin was approved in 2010 by the US FDA as a third-line therapy for metastatic breast cancer patients previously treated with an anthracycline and a taxane. In 2016, it was approved for treatment of metastatic liposarcoma for patients who have progressed with anthracycline treatment. In this article, we review the pharmacokinetics, mechanism of action of eribulin with focus on preclinical and clinical data in sarcoma and also the role of miRNAs in soft tissue sarcomas.

Advances in the treatment of soft tissue sarcoma: focus on eribulin

Eribulin mesylate is a synthetic derivative of halichondrin B isolated from a marine sponge. Its mechanism of action is through microtubule inhibition, which is different from that of taxanes. Eribulin has been approved for the treatment of metastatic breast cancer and more recently for non-operable or metastatic liposarcoma in patients who have received prior anthracycline chemotherapy. The major side effects of eribulin are bone marrow suppression including neutropenia, leukopenia, anemia, and fatigue/weakness, which can be well managed. In this article, we reviewed evidence from the latest published data on eribulin and its use in the treatment of soft tissue sarcomas. We explored the drug’s mechanism of action, pharmacodynamics, pharmacokinetics, and metabolism. Lastly, we reviewed all preclinical studies as well as clinical trials that investigated eribulin.

Eribulin in advanced breast cancer: safety, efficacy and new perspectives

Eribulin is a synthetic analog of halichondrin B belonging to microtubule-targeted agents with a distinct mechanism of inhibition of microtubule dynamics. This molecule has multiple nonmitotic effects on tumor biology, exhibiting effects on epithelial-mesenchimal transition and tumor vasculature. We review here preclinical and clinical studies on eribulin. The mitotic and nonmitotic effects together with its favorable safety profile make eribulin a unique drug with high potential in the treatment of metastatic breast cancer. The new emphasis of eribulin mechanism of action on vascular remodeling, microenvironment modifications and reversal of epithelial-mesenchimal transition paves the way to rethinking the use of the drug in an immunological perspective.

Safety and effectiveness of eribulin in Japanese patients with locally advanced or metastatic breast cancer: a post-marketing observational study

Background This large-scale study was conducted to evaluate the safety and effectiveness of eribulin for the treatment of inoperable or recurrent breast cancer in real-world settings in Japan. Methods Between July and December 2011, eligible patients with inoperable or recurrent breast cancer receiving eribulin for the first time were centrally registered and observed for 1 year. Eribulin was administered intravenously (1.4 mg/m²) on days 1 and 8 of every 3-week cycle. The primary endpoint was the frequency and intensity of adverse drug reactions (ADRs). Secondary endpoints included overall response rate (ORR) and time to treatment failure (TTF). Results Of 968 patients registered at 325 institutions, 951 and 671 were included in the safety and effectiveness analyses, respectively. In the safety population, ADRs were observed in 841 patients (88.4%). The most common (≥15% incidence) were neutropenia (66.6%), leukopenia (62.4%), lymphopenia (18.4%), and peripheral neuropathy (16.8%). The most common grade ≥ 3 ADRs (>5% incidence) were neutropenia (59.8%), leukopenia (50.5%), lymphopenia (16.1%), and febrile neutropenia (7.7%). In the effectiveness population, ORR was 16.5% (95% confidence interval: 13.7, 19.4). The median TTF was 127 days (95% confidence interval: 120, 134). Conclusions The safety and effectiveness profile of eribulin was consistent with prior studies. Eribulin had a favorable risk-benefit balance when used in real-world clinical settings.

Eribulin in advanced liposarcoma and leiomyosarcoma

INTRODUCTION

The heterogeneity of soft tissue sarcomas (STS) presents a formidable management challenge. Consequently, one of the main research goals is to define specific tailored therapy for each histological subtype and to develop a more personalised approach to treatment. The standard first line chemotherapy for advanced STS is doxorubicin, with or without ifosfamide, however, a number of different drugs are emerging as active therapies beyond first-line. Areas covered: Eribulin has recently been approved for advanced liposarcoma, after an anthracycline-containing regimen, demonstrating an overall survival (OS) advantage in liposarcoma and leiomyosarcoma in a randomised Phase III clinical trial. In this manuscript, an overview of the efficacy and safety of eribulin in STS is presented, highlighting different clinical outcomes between histological subtypes and comparing data with other effective drugs used in the treatment of sarcomas. The potential mechanisms of action of eribulin are also described, including its activity as potent microtubule-destabilizing anticancer agent, which has other antitumor biological effects. Expert commentary: Eribulin is highly effective in some STS populations and also has an acceptable toxicity profile. Further studies are required to better understand the precise mechanism of action of this agent and potential role in combination schedules.

Efficacy of eribulin in breast cancer: a short report on the emerging new data

Eribulin is a novel microtubule-targeting agent that is approved for the treatment of patients with locally advanced or metastatic breast cancer who have previously received treatment with an anthracycline and a taxane in either the adjuvant or metastatic setting. Eribulin induces mitotic catastrophe leading to cell death but has other important antitumor effects, including reversal of epithelial–mesenchymal transition and remodeling of the tumor vasculature. Eribulin was licensed for the treatment of advanced breast cancer based on results from two large randomized Phase III clinical trials. Current clinical trials of eribulin for breast cancer are evaluating response to treatment earlier in the patient pathway and in combination with other therapeutic agents. This review provides a short overview of emerging new data on the mode of action of eribulin in breast cancer.

Drug-induced hepatotoxicity in cancer patients - implication for treatment

INTRODUCTION

All anticancer drugs can cause idiosyncratic liver injury. Therefore, hepatoprotective agents assume particular importance to preserve liver function. Hepatic injury represents 10% of cases of acute hepatitis in adults; drug-related damage is still misjudged because of relative clinical underestimation and difficult differential diagnosis. Chemotherapeutic agents can produce liver toxicity through different pathways, resulting in different categories of liver injuries, but these drugs are not homogeneously hepatotoxic. Frequently, anticancer-induced hepatotoxicity is idiosyncratic and influenced by multiple factors.

AREAS COVERED

The aim of this paper is to perform a review of the literature regarding anticancer-induced liver toxicity. We described hepatotoxicity mechanisms of principal anticancer agents and respective dose reductions. Furthermore, we reviewed studies on hepatoprotectors and their optimal use. Tiopronin, magnesium isoglycyrrhizinate and S-Adenosylmethionine (AdoMet) demonstrated, in some small studies, a potential hepatoprotective activity.

EXPERT OPINION

Actually, in the literature only small experiences are reported. Even though hepatoprotective agents seem to be useful in the oncologic setting, the lack of well-designed prospective Phase III randomized controlled trials is a major limit in the introduction of hepatoprotectors in cancer patients and these kind of studies are warranted to support their use and to give further recommendations for the clinical practice.

Patient Management with Eribulin in Metastatic Breast Cancer: A Clinical Practice Guide

Eribulin, an antimicrotubule chemotherapeutic agent, is approved for the treatment of pretreated metastatic breast cancer (mBC) based on the positive outcomes of phase II and phase III clinical trials, which enrolled mainly Western patients. Eribulin has recently been approved in an increasing number of Asian countries; however, there is limited clinical experience in using the drug in certain countries. Therefore, we established an Asian working group to provide practical guidance for eribulin use based on our clinical experience. This paper summarizes the key clinical trials, and the management recommendations for the reported adverse events (AEs) of eribulin in mBC treatment, with an emphasis on those that are relevant to Asian patients, followed by further elaboration of our eribulin clinical experience. It is anticipated that this clinical practice guide will improve the management of AEs resulting from eribulin treatment, which will ensure that patients receive the maximum treatment benefit.

Pharmacokinetics of eribulin mesylate in cancer patients with normal and impaired renal function

Purpose

To evaluate the effect of renal impairment on eribulin mesylate pharmacokinetics following a single dose in adults with advanced solid tumors.

Methods

Patients were grouped by renal function: moderate impairment (creatinine clearance [CrCl] 30–50 mL/min), severe impairment (CrCl 15–29 mL/min), or normal (CrCl ≥80 mL/min). During each 21-day cycle, eribulin mesylate doses (days 1 and 8) were administered intravenously: moderate, 1.1 mg/m² (except cycle 1 day 1, 1.4 mg/m²); severe, 0.7 mg/m²; normal, 1.4 mg/m².

Results

Nineteen patients were enrolled (normal, n = 6; moderate, n = 7; severe, n = 6). Renal impairment was associated with an increased mean dose-normalized area under the concentration–time curve (ratios for moderate/normal and severe/normal: 1.49; 90 % confidence interval [CI] 0.9, 2.45). CrCl and renal function correlated positively, with a numerically small slope (0.0184; 90 % CI −0.00254, 0.0394). A simulated dose reduction to eribulin 1.1 mg/m² in patients with moderate or severe renal impairment achieved the same exposure as 1.4 mg/m² in those with normal renal function. All groups had similar toxicity profiles, with no unexpected adverse events.

Conclusions

Renal impairment decreased eribulin clearance and increased exposure. Pharmacokinetic evaluation supports an eribulin dose reduction to 1.1 mg/m² in patients with moderate or severe renal impairment.

ClinicalTrials.gov Identifier

NCT01418677.

Eribulin in Cancer Treatment

Halichondrin B is a complex, natural, polyether macrolide derived from marine sponges. Eribulin is a structurally-simplified, synthetic, macrocyclic ketone analogue of Halichondrin B. Eribulin was approved by United States Food and Drug Administration in 2010 as a third-line therapy for metastatic breast cancer patients who have previously been treated with an anthracycline and a taxane. It has a unique microtubule dynamics inhibitory action. Phase III studies have either been completed or are currently ongoing in breast cancer, soft tissue sarcoma, and non-small cell lung cancer. Phase I and II studies in multiple cancers and various combinations are currently ongoing. This article reviews the available information on eribulin with respect to its clinical pharmacology, pharmacokinetics, pharmacodynamics, mechanism of action, metabolism, preclinical studies, and with special focus on clinical trials.

Eribulin for the treatment of metastatic breast cancer: an update on its safety and efficacy

Breast cancer remains a leading cause of cancer-related death internationally. Treatment approaches for metastatic breast cancer have evolved in recent years; however chemotherapy remains a core component for the majority of patients. Agents such as anthracyclines and taxanes have been extensively studied and form standard treatment. Eribulin mesylate is a novel synthetic microtubule-directed chemotherapy, based on a naturally-occurring compound. Through phase I studies, eribulin was found to be tolerable and activity was seen in patients with metastatic breast cancer. Phase II studies in metastatic breast cancer further demonstrated its efficacy, with responses and survival which compare favorably with other studied chemotherapy agents. The phase III EMBRACE study showed superior survival for patients treated with eribulin compared with those who received a physician's choice control. This led to its approval for use in many countries in this setting. Its toxicity profile is well established and manageable for the most part, with the commonest reported toxicities being alopecia, fatigue, neutropenia and peripheral neuropathy. A second reported phase III study comparing eribulin to capecitabine failed to show an improvement in survival in pretreated patients. This article reviews the clinical pharmacology and mechanism of action of eribulin, and summarizes the results of the major preclinical and clinical studies of eribulin in metastatic breast cancer.

Eribulin in the Management of Advanced Breast Cancer: Implications of Current Research Findings

The search for cytotoxic agents from marine natural products ultimately led to the production of eribulin, which is a synthetic macrocyclic ketone analog of halichondrin B. Eribulin binds to tubulin to induce mitotic arrest and gained approval in Japan in May 2010; it was approved by the US Food and Drug Administration in November 2010 and the European Medicines Agency in March 2011 and was reimbursed by the Taiwan National Health Insurance in December 2014 for patients with metastatic breast cancer who had received at least one anthracycline and one taxane. The recommended regimen for eribulin mesylate comprises intravenous administration of 1.4 mg/m(2) (equivalent to 1.23 mg/m(2) eribulin) over two to five minutes on days 1 and 8 of a three-week cycle. Since 2011, various clinical investigations of eribulin monotherapy with dose or schedule modifications, combined use with other antineoplastic therapeutics, or head-to-head comparisons with specific agents have been performed in the management of advanced breast cancer. Ethnic-specific data from Japan and Korea indicate higher rates (>85%) of grade 3 or 4 neutropenia. Some anecdotal evidence suggests that eribulin can shrink brain and retinal metastases, which warrants further detailed studies. In this review, current observations of the effects of eribulin monotherapy are summarized and eribulin-backbone combination (bio-) chemotherapy is investigated.

Eribulin mesylate in breast cancer

Eribulin mesylate is a synthetic analog of halichondrin B (a polyether macrolide isolated from a marine sponge). It is a nontaxane microtubule dynamics inhibitor with a novel mechanism of action. It is the first drug that has demonstrated an improvement in overall survival as a single agent compared with the physician's choice of currently available treatments in locally advanced or metastatic breast cancer, previously treated with anthracyclines and taxanes. It has shown a good manageable tolerability profile. This drug has been approved by the US FDA and by the EMA for patients with locally advanced or metastatic breast cancer who have received at least two chemotherapeutic regimens for advanced/metastatic disease. Prior therapy should have included an anthracycline and a taxane in either the adjuvant or metastatic setting unless patients were not suitable for these treatments. The aim of this article is to describe the mechanism of action, pharmacokinetics, pharmacodynamics and the most relevant clinical trials in the development of this drug.

Population pharmacometric analyses of eribulin in patients with locally advanced or metastatic breast cancer previously treated with anthracyclines and taxanes

Pharmacometric investigation of eribulin was undertaken in patients with metastatic breast cancer (MBC) and other advanced solid tumors. A population pharmacokinetic (PK) model used data combined from seven phase 1 studies (advanced solid tumors; n = 129), and one phase 2 (MBC; n = 211), and one phase 3 study (MBC; n = 173). Phase 3 data were also used in a PK/pharmacodynamic (PD) model of efficacy and tumor response (sum of longest diameters of target lesions). All analyses used NONMEM 7.2. Eribulin PK, described by a dose-independent, three-compartment model with allometric relationship for body weight, was similar for all tumor types. Inter-individual variability (IIV) was 52% for both exposure and clearance. Liver function markers (albumin, alkaline phosphatase, bilirubin) significantly influenced eribulin PK (7.3% of IIV in clearance). Tumor shrinkage correlated with eribulin exposure; a 36% decrease in tumor size from baseline was modeled at week 36. No patient/disease factors significantly predicted eribulin's effect on tumor size. At week 6, a decrease in tumor size was associated with longer survival than an increase (P = .0055), suggesting survival may relate indirectly to eribulin exposure. These pharmacometric analyses provide a detailed overview of eribulin exposure-efficacy relationships to inform physicians treating patients with MBC.

Population pharmacokinetic-pharmacodynamic analysis for eribulin mesilate-associated neutropenia

AIMS

Eribulin mesilate is an inhibitor of microtubule dynamics that is approved for the treatment of late-stage metastatic breast cancer. Neutropenia is one of the major dose-limiting adverse effects of eribulin. The objective of this analysis was to develop a population pharmacokinetic-pharmacodynamic model for eribulin-associated neutropenia.

METHODS

A combined data set of 12 phase I, II and III studies for eribulin mesilate was analysed. The population pharmacokinetics of eribulin was described using a previously developed model. The relationship between eribulin pharmacokinetic and neutropenia was described using a semi-physiological lifespan model for haematological toxicity. Patient characteristics predictive of increased sensitivity to develop neutropenia were evaluated using a simulation framework.

RESULTS

Absolute neutrophil counts were available from 1579 patients. In the final covariate model, the baseline neutrophil count (ANC0) was estimated to be 4.03 × 10(9) neutrophils l(-1) [relative standard error (RSE) 1.2%], with interindividual variability (IIV, 37.3 coefficient of variation % [CV%]). The mean transition time was estimated to be 109 h (RSE 1.8%, IIV 13.9CV%), the feedback constant (γ) was estimated to be 0.216 (RSE 1.4%, IIV 12.2CV%), and the linear drug effect coefficient (SLOPE) was estimated to be 0.0451 μg l(-1) (RSE 3.2%, IIV 54CV%). Albumin, aspartate transaminase and receival of granulocyte colony-stimulating factor (G-CSF) were identified as significant covariates on SLOPE, and albumin, bilirubin, G-CSF, alkaline phosphatase and lactate dehydrogenase were identified as significant covariates on mean transition time.

CONCLUSIONS

The developed model can be applied to investigate optimal treatment strategies quantitatively across different patient groups with respect to neutropenia. Albumin was identified as the most clinically important covariate predictive of interindividual variability in the neutropenia time course.

Activity of eribulin mesylate in heavily pretreated breast cancer granted access via the Cancer Drugs Fund

AIM

Eribulin mesylate is a synthetic analog of halichondrin B and is licensed for the treatment of patients with locally advanced or metastatic breast cancer that has progressed following treatment with anthracyclines and taxanes. It was not deemed to be cost effective based on a cost analysis by the National Institute for Health and Care Excellence in England and therefore it is not funded routinely by the National Health Service. The establishment of the Cancer Drugs Fund in England subsequently enabled access. As with any new chemotherapy drug that enters clinical practice for metastatic breast cancer (MBC) it is often used in heavily pretreated patients and the experience in a routine clinical setting can differ from that in a clinical study. We therefore present the experience of the first 25 cases treated at our institution via the Cancer Drugs Fund.

MATERIALS & METHODS

A total of 25 patients were treated and in the 22 assessable cases the objective response rate was 18% (four out of 22), with a clinical benefit rate of 41.0% (9 out of 22).

RESULTS

The median time-to-progression and overall survival were 4.08 months and 5.89 months, respectively. There was a significant difference in clinical benefit rate (odds ratio: 0.065; 95% CI: 0-0.529; p = 0.0055), as well as time-to-progression (hazard ratio: 9.18; 95% CI: 2.26-37.38; p = 0.002 adjusted for age at diagnosis and interval between initial MBC diagnosis and commencing eribulin) favoring those patients who had not been rechallenged. There was no significant difference in overall survival (hazard ratio: 1.16; 95% CI: 0.44-3.05; p = 0.770 adjusted for age at diagnosis and interval between initial diagnosis of MBC and commencing eribulin).

CONCLUSION

Eribulin mesylate shows clinical activity; however, there appears to be differences in terms of benefit in patients based on whether patients have been rechallenged with an anthracycline and/or a taxane. These data require confirmation in larger patient groups.

Initial testing (stage 1) of eribulin, a novel tubulin binding agent, by the pediatric preclinical testing program

BACKGROUND

Antimitotic agents are essential components for curative therapy of pediatric acute leukemias and many solid tumors. Eribulin is a novel agent that differs from both Vinca alkaloids and taxanes in its mode of binding to tubulin polymers.

PROCEDURES

Eribulin was tested against the PPTP in vitro cell line panel at concentrations from 0.1 nM to 1.0 μM and against the PPTP in vivo xenograft panels at a dose of 1 mg/kg (solid tumors) or 1.5 mg/kg (ALL models) using a q4dx3 schedule repeated at Day 21.

RESULTS

In vitro eribulin demonstrated cytotoxic activity, with a median relative IC50 value of 0.27 nM, (range <0.1-14.8 nM). Eribulin was well tolerated in vivo, and all 43 xenograft models were considered evaluable for efficacy. Eribulin induced significant differences in event-free survival (EFS) distribution compared to control in 29 of 35 (83%) of the solid tumors and in 8 of 8 (100%) of the ALL xenografts. Objective responses were observed in 18 of 35 (51%) solid tumor xenografts. Complete responses (CR) or maintained CR were observed in panels of Wilms tumor, Ewing sarcoma, rhabdomyosarcoma, glioblastoma, and osteosarcoma xenografts. All eight ALL xenografts achieved CR or MCR.

CONCLUSIONS

The high level of activity observed for eribulin against the PPTP preclinical models makes this an interesting agent to consider for pediatric evaluation. The activity pattern observed for eribulin in the solid tumor panels is equal or superior to that observed previously for vincristine.