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

Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) methods for the therapeutic drug monitoring of cytotoxic anticancer drugs: An update

In the era of precision medicine, there is increasing evidence that conventional cytotoxic agents may be suitable candidates for therapeutic drug monitoring (TDM)- guided drug dosage adjustments and patient's tailored personalization of non-selective chemotherapies. To that end, many liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) assays have been developed for the quantification of conventional cytotoxic anticancer chemotherapies, that have been comprehensively and critically reviewed. The use of stable isotopically labelled internal standards (IS) of cytotoxic drugs was strikingly uncommon, accounting for only 48 % of the methods found, although their use could possible to suitably circumvent patients' samples matrix effects variability. Furthermore, this approach would increase the reliability of cytotoxic drug quantification in highly multi-mediated cancer patients with complex fluctuating pathophysiological and clinical conditions. LC-MS/MS assays can accommodate multiplexed analyses of cytotoxic drugs with optimal selectivity and specificity as well as short analytical times and, when using stable-isotopically labelled IS for quantification, provide concentrations measurements with a high degree of certainty. However, there are still organisational, pharmacological, and medical constraints to tackle before TDM of cytotoxic drugs can be more largely adopted in the clinics for contributing to our ever-lasting quest to improve cancer treatment outcomes.

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.

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.

Antibody-drug conjugates as targeted therapies: Are we there yet? A critical review of the current clinical landscape

Antibody-drug conjugates (ADCs) are targeted therapies with the expectation of broadened therapeutic window due to tumor-specific drug delivery. Recent approvals, including ADCs with a novel payload class, topoisomerase-1 inhibitors, generated renewed excitement in the field. We provide a critical review of approved and late-stage molecules, discuss strategies in solid tumors and ADCs outside oncology. Our pharmacokinetics-based assessment of targeting suggests that ADCs, especially in solid tumors, rely on additional mechanisms for efficacy including slow-release of the payload to the circulation at potentially efficacious levels. Further adjustments in the technology are needed to fulfill the promise of true targeted drug delivery.

A Review of Mathematical Models for Tumor Dynamics and Treatment Resistance Evolution of Solid Tumors

Increasing knowledge of intertumor heterogeneity, intratumor heterogeneity, and cancer evolution has improved the understanding of anticancer treatment resistance. A better characterization of cancer evolution and subsequent use of this knowledge for personalized treatment would increase the chance to overcome cancer treatment resistance. Model‐based approaches may help achieve this goal. In this review, we comprehensively summarized mathematical models of tumor dynamics for solid tumors and of drug resistance evolution. Models displayed by ordinary differential equations, algebraic equations, and partial differential equations for characterizing tumor burden dynamics are introduced and discussed. As for tumor resistance evolution, stochastic and deterministic models are introduced and discussed. The results may facilitate a novel model‐based analysis on anticancer treatment response and the occurrence of resistance, which incorporates both tumor dynamics and resistance evolution. The opportunities of a model‐based approach as discussed in this review can be of great benefit for future optimizing and personalizing anticancer treatment.

Pharmacodynamic analysis of eribulin safety in breast cancer patients using real-world postmarketing surveillance data

Postmarketing surveillance is useful to collect safety data in real-world clinical settings. In this study, we applied postmarketing real-world data on a mechanistic model analysis for neutropenic profiles of eribulin in patients with recurrent or metastatic breast cancer. Demographic and safety data were collected using an active surveillance method from eribulin-treated recurrent or metastatic breast cancer patients. Changes in neutrophil counts over time were analyzed using a mechanistic pharmacodynamic model. Pathophysiological factors that might affect the severity of neutropenia were investigated, and neutropenic patterns were simulated for different treatment schedules. Clinical and laboratory data were collected from 401 patients (5199 neutrophil count measurements) who had not received granulocyte colony-stimulating factor and were eligible for pharmacodynamic analysis. The estimated mean parameters were as follows: mean transit time = 104.5 h, neutrophil proliferation rate constant = 0.0377 h-1 , neutrophil elimination rate constant = 0.0295 h-1 , and linear coefficient of drug effect = 0.0413 mL/ng. Low serum albumin levels and low baseline neutrophil counts were associated with severe neutropenia. The probability of grade ≥3 neutropenia was predicted to be 69%, 27%, and 27% for patients on standard, biweekly, and triweekly treatment scenarios, respectively, based on virtual simulations using the developed pharmacodynamic model. In conclusion, this is the first application of postmarketing surveillance data to a model-based safety analysis. This analysis of safety data reflecting authentic clinical settings will provide useful information on the safe use and potential risk factors of eribulin.

Emerging roles for clinical pharmacometrics in cancer precision medicine

Purpose of review

Although significant progress has been made in cancer research, there exist unmet needs in patient care as reflected by the 'Cancer Moonshot' goals. This review appreciates the potential utility of quantitative pharmacology in cancer precision medicine.

Recent findings

Precision oncology has received federal funding largely due to 'The Precision Medicine Initiative'. Precision medicine takes into account the inter-individual variability, and allows for tailoring the right medication or the right dose of drug to the best subpopulation of patients who will likely respond to the intervention, thus enhancing therapeutic success and reducing "financial toxicity" to patients, families and caregivers. The National Cancer Institute (NCI) committed US$ 70 million from its fiscal year 2016 budget to advance precision oncology research. Through the 'Critical Path Initiative', pharmacometrics has gained an important role in drug development; however, it is yet to find widespread clinical applicability.

Summary

Stakeholders including clinicians and pharmacometricians need to work in concert to ensure that benefits of model-based approaches are harnessed to personalize cancer care to the individual needs of the patient via better dosing strategies, companion diagnostics, and predictive biomarkers. In medical oncology, where immediate patient care is the clinician's primary concern, pharmacometric approaches can be tailored to build models that rely on patient data already digitally available in the Electronic Health Record (EHR) to facilitate quick collaboration and avoid additional funding needs. Taken together, we offer a roadmap for the future of precision oncology which is fraught with both challenges and opportunities for pharmacometricians and clinicians alike.

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.

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.

Disease Progression/Clinical Outcome Model for Castration-Resistant Prostate Cancer in Patients Treated With Eribulin

Frameworks that associate cancer dynamic disease progression models with parametric survival models for clinical outcome have recently been proposed to support decision making in early clinical development. Here we developed such a disease progression clinical outcome model for castration-resistant prostate cancer (CRPC) using historical phase II data of the anticancer agent eribulin. Disease progression was captured using the dynamics of prostate-specific antigen (PSA). For clinical outcome, overall survival (OS) was used. The model for PSA dynamics comprised parameters for baseline PSA (23.2 ng/ml, relative standard error (RSE) 16.5%), growth rate (0.00879 day(-1), RSE 12.6%), drug effect (0.241 µg·h·l(-1) day(-1), RSE 32.6%), and resistance development (0.0113 day(-1), RSE 44.3%). OS was modeled according to a Weibull distribution. Predictors for survival included model-predicted PSA time to nadir (TTN), PSA growth rate, Eastern Cooperative Oncology Group (ECOG) score, and baseline PSA. The developed framework can be considered to support informative design and analysis of drugs developed for CRPC.

Integrated Simulation Framework for Toxicity, Dose Intensity, Disease Progression, and Cost Effectiveness for Castration-Resistant Prostate Cancer Treatment With Eribulin

Quantitative model-based analyses are helpful to support decision-making in drug development. In oncology, disease progression/clinical outcome (DPCO) models have been used for early predictions of clinical outcome, but most of such approaches did not include adverse events or dose intensity. In addition, cost-effectiveness evaluations of investigational compounds are becoming increasingly important. Here, we developed an integrated model-based framework including relevant treatment effects for patients with castration-resistant prostate cancer treated with the anticancer agent eribulin. The framework included (i) a DPCO model relating prostate-specific antigen (PSA) dynamics to survival; (ii) models for adverse events including dose-limiting neutropenia and other graded toxicities; (iii) a model for Eastern Cooperative Oncology Group (ECOG) performance score; (iv) a model for dropout; (v) the consideration of cost effectiveness. The model allowed simulation of realistic treatment courses. Subsequently, simulations evaluating alternative treatment protocols or patient characteristics were performed in order to derive inferences on expected efficacy and cost effectiveness.

Systemic treatment approaches in her2-negative advanced breast cancer-guidance on the guidelines

Despite advancements in the treatment of early-stage breast cancer, many patients still develop disease recurrence; others present with de novo metastatic disease. For most patients with advanced breast cancer, the primary treatment intent is noncurative-that is, palliative-in nature. The goals of treatment should therefore focus on maximizing symptom control and extending survival. Treatments should be evaluated on an individualized basis in terms of evidence, but also with full respect for the wishes of the patient in terms of acceptable toxicity. Given the availability of extensive reviews on the roles of endocrine therapy and her2 (human epidermal growth factor receptor 2)-targeted therapies for advanced disease, we focus here mainly on treatment guidelines for the non-endocrine management of her2-negative advanced breast cancer in a Canadian health care context.