Combination vinorelbine and capecitabine for metastatic breast cancer using a non-body surface area dosing scheme

Opportunities for Precision Dosing of Cytotoxic Drugs in Non-Small Cell Lung Cancer: Bridging the Gap in Precision Medicine

Precision dosing of classical cytotoxic drugs in oncology remains underdeveloped, especially in treating non-small cell lung cancer (NSCLC). Despite advancements in targeted therapy and immunotherapy, classical cytotoxic agents continue to play a critical role in NSCLC treatment. However, the current body surface area (BSA)-based dosing of these agents fails to adequately address interindividual variability in pharmacokinetics. By better considering patient characteristics, treatment outcomes can be improved, reducing risks of under-exposure and over-exposure. This narrative review explores opportunities for precision dosing for key cytotoxic agents used in NSCLC treatment: cisplatin, carboplatin, pemetrexed, docetaxel, (nab-)paclitaxel, gemcitabine, and vinorelbine. A comprehensive review of regulatory reports and an extensive literature search were conducted to evaluate current dosing practices, pharmacokinetics, pharmacodynamics, and exposure-response relationships. Our findings highlight promising developments in precision dosing, although the number of directly implementable strategies remains limited. The most compelling evidence supports using the biomarker cystatin C for more precise carboplatin dosing and adopting weekly dosing schedules for docetaxel, paclitaxel, and nab-paclitaxel. Additionally, we recommend direct implementation of therapeutic drug monitoring (TDM)-guided dosing for paclitaxel. This review stresses the urgent need to reassess conventional dosing paradigms for classical cytotoxic agents to better align with the principles of the precision dosing framework. Our recommendations show the potential of precision dosing to improve NSCLC treatment, addressing gaps in the current dosing of classical cytotoxic drugs. Given the large NSCLC patient population, optimising the dosing of these agents could significantly improve treatment outcomes and reduce toxicity for many patients.

Impact of pharmacogenetics on variability in exposure to oral vinorelbine among pediatric patients: a model-based population pharmacokinetic analysis

PURPOSE

Better understanding of pharmacokinetics of oral vinorelbine (VNR) in children would help predicting drug exposure and, beyond, clinical outcome. Here, we have characterized the population pharmacokinetics of oral VNR and studied the factors likely to explain the variability observed in VNR exposure among young patients.

DESIGN/METHODS

We collected blood samples from 36 patients (mean age 11.6 years) of the OVIMA multicentric phase II study in children with recurrent/progressive low-grade glioma. Patients received 60 mg/m² of oral VNR on days 1, 8, and 15 during the first 28-day treatment cycle and 80 mg/m², unless contraindicated, from cycle 2-12. Population pharmacokinetic analysis was performed using nonlinear mixed-effects modeling within the Monolix^® software. Fifty SNPs of pharmacokinetic-related genes were genotyped. The influence of demographic, biological, and pharmacogenetic covariates on pharmacokinetic parameters was investigated using a stepwise multivariate procedure.

RESULTS

A three-compartment model, with a delayed double zero-order absorption and a first-order elimination, best described VNR pharmacokinetics in children. Typical population estimates for the apparent central volume of distribution (V_c/F) and elimination rate constant were 803 L and 0.60 h^-1, respectively. Following covariate analysis, BSA, leukocytes count, and drug transport ABCB1-rs2032582 SNP showed a dramatic impact on V_c/F. Conversely, age and sex had no significant effect on VNR pharmacokinetics.

CONCLUSION

Beyond canonical BSA and leukocytes, ABCB1-rs2032582 polymorphism showed a meaningful impact on VNR systemic exposure. Simulations showed that the identified covariates could have an impact on both efficacy and toxicity outcomes. Thus, a personalized dosing strategy, using those covariates, could help to optimize the efficacy/toxicity balance of VNR in children.

Pharmacogenomics Testing in Phase I Oncology Clinical Trials: Constructive Criticism Is Warranted

Simple Summary

Phase I clinical trials are a cornerstone of pharmaceutical development in oncology. Many studies have now attempted to incorporate pharmacogenomics into phase I studies; however, many of these studies have fundamental flaws that that preclude interpretation and application of their findings. Study populations are often small and heterogeneous with multiple disease states, multiple dose levels, and prior therapies. Genetic testing typically includes few variants in candidate genes that do no encapsulate the full range of phenotypic variability in protein function. Moreover, a plurality of these studies do not present scientifically robust clinical or preclinical justification for undertaking pharmacogenomics studies. A significant amount of progress in understanding pharmacogenomic variability has occurred since pharmacogenomics approaches first began appearing in the literature. This progress can be immediately leveraged for the vast majority of Phase I studies. The purpose of this review is to summarize the current literature pertaining to Phase I incorporation of pharmacogenomics studies, analyze potential flaws in study design, and suggest approaches that can improve design of future scientific efforts.

Abstract

While over ten-thousand phase I studies are published in oncology, fewer than 1% of these studies stratify patients based on genetic variants that influence pharmacology. Pharmacogenetics-based patient stratification can improve the success of clinical trials by identifying responsive patients who have less potential to develop toxicity; however, the scientific limits imposed by phase I study designs reduce the potential for these studies to make conclusions. We compiled all phase I studies in oncology with pharmacogenetics endpoints (n = 84), evaluating toxicity (n = 42), response or PFS (n = 32), and pharmacokinetics (n = 40). Most of these studies focus on a limited number of agent classes: Topoisomerase inhibitors, antimetabolites, and anti-angiogenesis agents. Eight genotype-directed phase I studies were identified. Phase I studies consist of homogeneous populations with a variety of comorbidities, prior therapies, racial backgrounds, and other factors that confound statistical analysis of pharmacogenetics. Taken together, phase I studies analyzed herein treated small numbers of patients (median, 95% CI = 28, 24–31), evaluated few variants that are known to change phenotype, and provided little justification of pharmacogenetics hypotheses. Future studies should account for these factors during study design to optimize the success of phase I studies and to answer important scientific questions.

Optimized Dosing: The Next Step in Precision Medicine in Non-Small-Cell Lung Cancer

In oncology, and especially in the treatment of non-small-cell lung cancer (NSCLC), dose optimization is often a neglected part of precision medicine. Many drugs are still being administered in "one dose fits all" regimens or based on parameters that are often only minor determinants for systemic exposure. These dosing approaches often introduce additional pharmacokinetic variability and do not add to treatment outcomes. Fortunately, pharmacological knowledge is increasing, providing valuable information regarding the potential of, for example, therapeutic drug monitoring. This article focuses on the evidence for the most promising and easily implemented optimized dosing approaches for the small-molecule inhibitors, chemotherapeutic agents, and monoclonal antibodies as treatment options currently approved for NSCLC. Despite limitations such as investigations having been conducted in oncological diseases other than NSCLC or the retrospective origin of many analyses, an alternative dosing regimen could be beneficial for treatment outcomes, prescriber convenience, or financial burden on healthcare systems. This review of the literature provides recommendations on the implementation of dose optimization and advice regarding promising strategies that deserve further research in NSCLC.

Evaluation of body-surface-area adjusted dosing of high-dose methotrexate by population pharmacokinetics in a large cohort of cancer patients

Background

The aim of this study was to identify sources of variability including patient gender and body surface area (BSA) in pharmacokinetic (PK) exposure for high-dose methotrexate (MTX) continuous infusion in a large cohort of patients with hematological and solid malignancies.

Methods

We conducted a retrospective PK analysis of MTX plasma concentration data from hematological/oncological patients treated at the University Hospital of Cologne between 2005 and 2018. Nonlinear mixed effects modeling was performed. Covariate data on patient demographics and clinical chemistry parameters was incorporated to assess relationships with PK parameters. Simulations were conducted to compare exposure and probability of target attainment (PTA) under BSA adjusted, flat and stratified dosing regimens.

Results

Plasma concentration over time data (2182 measurements) from therapeutic drug monitoring from 229 patients was available. PK of MTX were best described by a three-compartment model. Values for clearance (CL) of 4.33 [2.95–5.92] L h^− 1 and central volume of distribution of 4.29 [1.81–7.33] L were estimated. An inter-occasion variability of 23.1% (coefficient of variation) and an inter-individual variability of 29.7% were associated to CL, which was 16 [7–25] % lower in women. Serum creatinine, patient age, sex and BSA were significantly related to CL of MTX. Simulations suggested that differences in PTA between flat and BSA-based dosing were marginal, with stratified dosing performing best overall.

Conclusion

A dosing scheme with doses stratified across BSA quartiles is suggested to optimize target exposure attainment. Influence of patient sex on CL of MTX is present but small in magnitude.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08443-x.

Comparison of toxicity and effectiveness between fixed-dose and body surface area-based dose capecitabine

BACKGROUND

Capecitabine is generally dosed based on body surface area (BSA). This dosing strategy has several limitations; however, evidence for alternative strategies is lacking. Therefore, we analyzed the toxicity and effectiveness of fixed-dose capecitabine and compared this strategy with a BSA-based dose of capecitabine in a large set of patients.

METHODS

Patients treated with fixed-dose capecitabine between 2003 and 2015 were studied. A comparable group of patients, dosed based on BSA, was chosen as a control cohort. A total of two combined scores were used: capecitabine-specific toxicity (diarrhea, National Cancer Institute Common Toxicity Criteria grade ⩾3, hand-foot syndrome ⩾2, or neutropenia ⩾2), and clinically relevant events due to toxicity, that is, hospital admission, dose reduction, or discontinuation. Per treatment regimen, patients were divided into three BSA groups based on BSA quartiles corrected for sex. Toxicity scores were compared by a Chi-square test between cohorts, and within cohorts using BSA groups. Progression-free survival (PFS) was estimated by the Kaplan-Meier method.

RESULTS

A total of 2319 patients were included (fixed dosed, n = 1126 and BSA-based dose, n = 1193). Overall, four regimens were evaluated: capecitabine-radiotherapy (n = 1178), capecitabine-oxaliplatin (n = 519), capecitabine triplet (n = 181) and capecitabine monotherapy (n = 441). The incidence of capecitabine-specific toxicity and clinically relevant events was comparable between fixed-dose and BSA-dosed patients, while a small difference (7.1%) in absolute dose was found. Both cohorts showed only a higher incidence of both toxicity scores in the lowest BSA group of the capecitabine-radiotherapy group (p < 0.05). Subgroups of the fixed-dose cohort analyzed for PFS, showed no differences between BSA groups.

CONCLUSIONS

Fixed-dose capecitabine is as comparably well tolerated and effective as BSA-based dosing and could be considered as a reasonable alternative for BSA-based dosing.

Breath tests to phenotype drug disposition in oncology

Breath tests (BTs) have been investigated as diagnostic tools to phenotype drug disposition in cancer patients in the pursuit to individualize drug treatment. The choice of the right phenotype probe is crucial and depends on the metabolic pathway of the anticancer agent of interest. BTs using orally or intravenously administered selective non-radioactive (13)C-labeled probes to non-invasively evaluate dihydropyrimidine dehydrogenase, cytochrome P450 (CYP) 3A4, and CYP2D6 enzyme activity have been published. Clinically, a (13)C-dextromethorphan BT to predict endoxifen levels in breast cancer patients and a (13)C-uracil BT to predict fluoropyrimidine toxicity in colorectal cancer patients are most promising. However, the clinical benefit and cost effectiveness of these phenotype BTs need to be determined in order to make the transition from an experimental setting to clinical practice as companion diagnostic tests.

OATP1B1 polymorphism as a determinant of erythromycin disposition

Previous studies have demonstrated that the pharmacokinetic profile of erythromycin, a probe for CYP3A4 activity, is affected by inhibitors or inducers of hepatic solute carriers. We hypothesized that these interactions are mediated by OATP1B1 (gene symbol, SLCO1B1), a polypeptide expressed on the basolateral surface of hepatocytes. Using stably transfected Flp-In T-Rex293 cells, erythromycin was found to be a substrate for OATP1B1*1A (wild type) with a Michaelis-Menten constant of ~13 µmol/l, and that its transport was reduced by ~50% in cells expressing OATP1B1*5 (V174A). Deficiency of the ortholog transporter Oatp1b2 in mice was associated with a 52% decrease in the metabolic rate of erythromycin (P = 0.000043). In line with these observations, in humans the c.521T>C variant in SLCO1B1 (rs4149056), encoding OATP1B1*5, was associated with a decline in erythromycin metabolism (P = 0.0072). These results suggest that impairment of OATP1B1 function can alter erythromycin metabolism, independent of changes in CYP3A4 activity.

Covariate pharmacokinetic model building in oncology and its potential clinical relevance

When modeling pharmacokinetic (PK) data, identifying covariates is important in explaining interindividual variability, and thus increasing the predictive value of the model. Nonlinear mixed-effects modeling with stepwise covariate modeling is frequently used to build structural covariate models, and the most commonly used software-NONMEM-provides estimations for the fixed-effect parameters (e.g., drug clearance), interindividual and residual unidentified random effects. The aim of covariate modeling is not only to find covariates that significantly influence the population PK parameters, but also to provide dosing recommendations for a certain drug under different conditions, e.g., organ dysfunction, combination chemotherapy. A true covariate is usually seen as one that carries unique information on a structural model parameter. Covariate models have improved our understanding of the pharmacology of many anticancer drugs, including busulfan or melphalan that are part of high-dose pretransplant treatments, the antifolate methotrexate whose elimination is strongly dependent on GFR and comedication, the taxanes and tyrosine kinase inhibitors, the latter being subject of cytochrome p450 3A4 (CYP3A4) associated metabolism. The purpose of this review article is to provide a tool to help understand population covariate analysis and their potential implications for the clinic. Accordingly, several population covariate models are listed, and their clinical relevance is discussed. The target audience of this article are clinical oncologists with a special interest in clinical and mathematical pharmacology.

Pharmacogenetics in breast cancer: steps toward personalized medicine in breast cancer management

There is wide individual variability in the pharmacokinetics, pharmacodynamics, and tolerance to anticancer drugs within the same ethnic group and even greater variability among different ethnicities. Pharmacogenomics (PG) has the potential to provide personalized therapy based on individual genetic variability in an effort to maximize efficacy and reduce adverse effects. The benefits of PG include improved therapeutic index, improved dose regimen, and selection of optimal types of drug for an individual or set of individuals. Advanced or metastatic breast cancer is typically treated with single or multiple combinations of chemotherapy regimens including anthracyclines, taxanes, antimetabolites, alkylating agents, platinum drugs, vinca alkaloids, and others. In this review, the PG of breast cancer therapeutics, including tamoxifen, which is the most widely used therapeutic for the treatment of hormone-dependent breast cancer, is reviewed. The pharmacological activity of tamoxifen depends on its conversion by cytochrome P450 2D6 (CYP2D6) to its abundant active metabolite, endoxifen. Patients with reduced CYP2D6 activity, as a result of either their genotype or induction by the coadministration of other drugs that inhibit CYP2D6 function, produce little endoxifen and hence derive limited therapeutic benefit from tamoxifen; the same can be said about the different classes of therapeutics in breast cancer. PG studies of breast cancer therapeutics should provide patients with breast cancer with optimal and personalized therapy.

Intravenous versus oral vinorelbine plus capecitabine as second-line treatment in advanced breast cancer patients. A retrospective comparison of two consecutive phase II studies

Vinorelbine (i.v.) plus capecitabine (oral) combination therapy is active in anthracycline/taxane pretreated patients with metastatic breast cancer. Availability of oral vinorelbine provides this combination in an all-oral formulation. Two consecutive phase II trials differing only in vinorelbine administration routes evaluated their respective activities and tolerabilities in this population. In the i.v. group (n = 38) disease control was 61% (37% PR, 24% SD), median TTP 6.8 months and median survival 11.3 months. In the oral group (n = 38) disease control was 77% (5.4% CR, 34% PR, 38% SD), median TTP 7 months and median survival 10 months. G3-G4 neutropenia was more common in the oral group (p < 0.05); G2-G3 anaemia [5] and G3 thrombocytopenia [1] were observed only in the oral group. Although the comparison between the two regimens was not randomized, the results observed in these two consecutive phase II studies may suggest that oral and iv vinorelbine, in combination with capecitabine, can achieve similar responses in patients with metastatic breast cancer refractory to anthra-taxane combinations.

A Phase II trial of the combination of vinorelbine and capecitabine as second-line treatment in metastatic breast cancer previously treated with taxanes and/or anthracyclines

PURPOSE

Survival time for metastatic breast cancer (MBC) can be substantially improved by combination chemotherapy in the adjuvant setting. Capecitabine and vinorelbine have shown considerable efficacy and favourable toxicity as single agents. The aim of this study is to evaluate the response to the combination of capecitabine and vinorelbine as second-line treatment in patients previously treated with taxanes and/or anthracyclines.

PATIENTS AND METHODS

Thirty-nine patients with MBC, who received a combination of vinorelbine and capecitabine were included in the study.

RESULTS

Overall response rate was 53.9% and disease progression rate was 28.2% for patients who received six cycles of therapy, rates significantly higher than the three-cycle group. The treatment was generally well tolerated and toxicity was mild.

CONCLUSIONS

The combination of capecitabine and vinorelbine as salvage therapy in anthracycline- and/or taxane-pre-treated patients with MBC seems to be effective and safe, even more so as the number of treatment cycles increases.

Pharmacokinetics and pharmacogenomics in breast cancer chemotherapy

Locally advanced or metastatic breast cancer is typically treated with chemotherapy. Multiple combinations of chemotherapy regimens are available, including anthracyclines, taxanes, antimetabolites, alkylating agents, platinum drugs and vinca alkaloids. This review discusses the pharmacokinetic and pharmacogenomic information available for commonly used breast cancer chemotherapy drugs. Pharmacogenomic associations for many drugs have yet to be identified or validated in breast cancer. Further work is needed to identify markers to screen breast cancer patients prior to therapy selection.

Part II: Liver function in oncology: towards safer chemotherapy use

The liver is fundamentally important in drug metabolism. In oncology, the astute clinician must not only understand the meaning and limitations of commonly ordered liver biochemical tests, but also be aware of which anticancer agents might induce liver dysfunction, and of the strategies for appropriate dosing of patients with pre-existing liver dysfunction. In part I of our Review, we highlighted both the importance and inadequacies of identifying serum biochemical liver abnormalities in oncology; we also discussed a lack of routine formal investigation of liver function. We summarised chemotherapy-related hepatotoxicity and other causes of liver toxic effects in patients with cancer. Here in part II, we discuss trials that have specifically assessed chemotherapy dosing strategies in the setting of overt biochemical liver dysfunction and we note their recommendations. Furthermore, we review other assessments of liver metabolic and excretory function, particularly in the setting of chemotherapy drug handling. We discuss the potential use of these metabolic probes in practice.

Do single nucleotide polymorphisms in xenobiotic metabolizing genes determine breast cancer susceptibility and treatment outcomes?

SNPs in CYP1A1, CYP2A1, CYP2B6, CYP2C, CYP2D6, CYP3A, GSTM1, GSTT1, GSTP1, SULT1A1, SULT1A2, UGT, and MTHFR are associated with breast cancer susceptibility; however, lack of such associations are also reported in some populations. The contradictory findings are explained on the basis of ethnic variation among populations and due to lack of proper sample size, detailed genotype-phenotype combinations and validation of gene expression studies at protein level. In this review, SNPs in these genes that have tremendous potential in identification of susceptible individuals, development of preventive strategies, treatment outcomes and their limitations are discussed.

Flat-fixed dosing versus body surface area based dosing of anticancer drugs in adults: does it make a difference?

The current practice of using body-surface area (BSA) in dosing anticancer agents was implemented in clinical oncology half a century ago. By correcting for BSA, it was generally assumed that cancer patients would receive a dose of a particular cytotoxic drug associated with an acceptable degree of toxicities without reducing the agent's therapeutic effect. More recently, doubt has arisen to this hypothesis, and for many drugs, the effects of BSA on the pharmacokinetics of these agents have therefore been studied retrospectively. In (by far) most cases, use of BSA does not reduce the interindividual variation in the pharmacokinetics of adults, and thus, a logical rationale for further use of this tool in dosing adults is lacking. As a result, alternative dosing strategies have been proposed in order to replace BSA-based dosing. Flat-fixed dosing regimens have been suggested, thereby avoiding potential dose calculation mistakes. As flat-fixed dosing does not typically lead to greater pharmacokinetic variability, it does not seem worse than using BSA-based dosing. While it provides a simplification, it can, however, be questioned whether to call this an improvement or not. The implementation of so-called genotyping and phenotyping strategies, and therapeutic drug monitoring, may probably be of more clinical value. In the end, the nonscientifically based BSA-based dosing strategy should be replaced by alternative strategies. Despite the lack of basic fundamentals, BSA-based dosing still seems "untouchable" in clinical oncology. Even when alternatives will be shown to be indisputably better, many hurdles will probably have to be overcome before physicians will be willing to ban BSA-based dosing. Disclosure of potential conflicts of interest is found at the end of this article.

Molecular pharmacokinetics of catharanthus (vinca) alkaloids

This review focuses on the published data regarding the molecular determinants (enzymes, transporters, orphan nuclear receptors) of Catharanthus (vinca) alkaloids pharmacokinetics in humans. The clinical impact of these determinants (drug disposition, drug-drug interactions) is also discussed.