Impact of Older Age on the Exposure of Paclitaxel: a Population Pharmacokinetic Study

Peripheral Neuropathy Incidence in Children, and Adolescents and Young Adults With Cancer and Medicaid Insurance in California

PURPOSE

Chemotherapy-induced peripheral neuropathy is a potentially debilitating adverse effect of cancer therapy that can lead to delay, reduction, or discontinuation of cancer treatment. Population-based data on peripheral neuropathy incidence among young cancer survivors are lacking.

METHODS

Using a linkage between Medicaid, the California Cancer Registry, and hospitalization and emergency department data, we identified 6,028 adolescents and young adults (15-39 years) with Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), breast cancer, colorectal cancer, or testicular cancer and 418 children (<15 years) with HL or NHL during 2005-2017. We determined the cumulative incidence of peripheral neuropathy and its association with neurotoxic chemotherapy identified from Medicaid claims, using multivariable Cox proportional hazards regression models.

RESULTS

Of 6,446 patients, 1,007 were diagnosed with peripheral neuropathy. Across each cancer type, incidence was higher among patients receiving neurotoxic drugs. For example, compared with non-neurotoxic agents, 5-year cumulative incidence was higher with oxaliplatin for colorectal cancer (24.0% v 6.2%) and paclitaxel for breast cancer (22.6% v 5.1%). In multivariable analysis, the agents most strongly associated with peripheral neuropathy were brentuximab (±other neurotoxic drugs) for HL (hazard ratio [HR], 9.53 [95% CI, 5.95 to 15.26]); brentuximab (±vinca alkaloids; HR, 7.00 [95% CI, 4.13 to 11.87]) for NHL, paclitaxel for breast cancer (HR, 4.03 [95% CI, 3.05 to 5.31]); oxaliplatin for colorectal cancer (HR, 3.46 [95% CI, 2.23 to 5.36]); and cisplatin and etoposide for testicular cancer (HR, 2.06 [95% CI, 1.37 to 3.11]).

CONCLUSION

The high incidence of peripheral neuropathy highlights the need for frequent monitoring, new supportive care approaches, and development of novel therapeutic agents to minimize toxicity while maintaining treatment efficacy.

Synergy of Body Composition, Exercise Oncology, and Pharmacokinetics: A Narrative Review of Personalizing Paclitaxel Treatment for Breast Cancer

BACKGROUND/OBJECTIVES

Paclitaxel is a type of small molecule chemotherapy widely used for breast cancer, but its clinical efficacy is often hindered by dose-limiting toxicities such as chemotherapy-induced peripheral neuropathy and neutropenia. Traditional dosing based on body surface area does not account for variations in body composition, which may influence paclitaxel metabolism, toxicity, and treatment outcomes. This review explores the interplay between body composition, physical activity, and paclitaxel pharmacokinetics, emphasizing the potential for personalized dosing strategies.

METHODS

A comprehensive narrative review was conducted by analyzing the literature on body composition, small molecule chemotherapy-related toxicities, pharmacokinetics, and exercise oncology. Studies examining the role of skeletal muscle mass, adipose tissue, and physical activity in modulating paclitaxel metabolism and side effects were included.

RESULTS

Evidence suggests that patients with low skeletal muscle mass are at a higher risk of paclitaxel-induced toxicities due to altered drug distribution and clearance. Sarcopenic obesity, characterized by low muscle and high-fat levels, further exacerbates these risks. Exercise, particularly resistance and aerobic training, has been shown to improve muscle mass, mitigate toxicities, and enhance chemotherapy tolerance. However, the precise mechanisms by which exercise influences paclitaxel pharmacokinetics remain underexplored.

CONCLUSIONS

Personalized chemotherapy dosing, considering body composition and physical activity, may optimize paclitaxel treatment outcomes. Future research should focus on integrating exercise interventions into oncology care and refining dosing models that account for interindividual differences in drug metabolism. These advancements could improve treatment efficacy while minimizing toxicities in breast cancer patients.

Paclitaxel therapeutic drug monitoring - International association of therapeutic drug monitoring and clinical toxicology recommendations

Paclitaxel, one of the most frequently used anticancer drugs, is dosed by body surface area, which leads to substantial inter-individual variability in systemic drug exposure. We evaluated clinical evidence regarding the scientific rationale and clinical benefit of individualized paclitaxel dosing based on measured systemic concentrations, known as therapeutic drug monitoring (TDM). In retrospective studies, higher systemic exposure is associated with greater toxicity and efficacy of paclitaxel treatment across several disease types and dosing regimens. In prospective trials, TDM reduces variability in systemic exposure, and has been demonstrated to reduce toxicity while retaining treatment efficacy for 3-weekly dosing in patients with advanced non-small cell lung cancer. Despite the demonstrated benefits of paclitaxel TDM, clinical adoption has been limited due to the challenges with sample collection and analysis. Based on our review, we strongly recommend TDM for patients receiving every 3-week paclitaxel in combination with a platinum agent for advanced NSCLC, due to the prospectively demonstrated clinical benefits, and find moderate evidence to recommend TDM for paclitaxel 3-hour infusions for other tumor types and preliminary evidence suggesting potential usefulness for paclitaxel administered by 1-hour infusions.

Semi-physiological Enriched Population Pharmacokinetic Modelling to Predict the Effects of Pregnancy on the Pharmacokinetics of Cytotoxic Drugs

BACKGROUND AND OBJECTIVE

As a result of changes in physiology during pregnancy, the pharmacokinetics (PK) of drugs can be altered. It is unclear whether under- or overexposure occurs in pregnant cancer patients and thus also whether adjustments in dosing regimens are required. Given the severity of the malignant disease and the potentially high impact on both the mother and child, there is a high unmet medical need for adequate and tolerable treatment of this patient population. We aimed to develop and evaluate a semi-physiological enriched model that incorporates physiological changes during pregnancy into available population PK models developed from non-pregnant patient data.

METHODS

Gestational changes in plasma protein levels, renal function, hepatic function, plasma volume, extracellular water and total body water were implemented in existing empirical PK models for docetaxel, paclitaxel, epirubicin and doxorubicin. These models were used to predict PK profiles for pregnant patients, which were compared with observed data obtained from pregnant patients.

RESULTS

The observed PK profiles were well described by the model. For docetaxel, paclitaxel and doxorubicin, an overprediction of the lower concentrations was observed, most likely as a result of a lack of data on the gestational changes in metabolizing enzymes. For paclitaxel, epirubicin and doxorubicin, the semi-physiological enriched model performed better in predicting PK in pregnant patients compared with a model that was not adjusted for pregnancy-induced changes.

CONCLUSION

By incorporating gestational changes into existing population pharmacokinetic models, it is possible to adequately predict plasma concentrations of drugs in pregnant patients which may inform dose adjustments in this population.

Albumin-Bound Paclitaxel: Worthy of Further Study in Sarcomas

Taxanes (paclitaxel and docetaxel) play an important role in the treatment of advanced sarcomas. Albumin-bound paclitaxel (nab-paclitaxel) is a new kind of taxane and has many advantages compared with paclitaxel and docetaxel. Nab-paclitaxel is currently approved for the treatment of advanced breast, non-small cell lung, and pancreatic cancers. However, the efficacy of nab-paclitaxel in sarcomas has not been reviewed. In this review, we first compare the similarities and differences among nab-paclitaxel, paclitaxel, and docetaxel and then summarize the efficacy of nab-paclitaxel against various non-sarcoma malignancies based on clinical trials with reported results. The efficacy and clinical research progress on nab-paclitaxel in sarcomas are also summarized. This review will serve as a good reference for the application of nab-paclitaxel in clinical sarcoma treatment studies and the design of clinical trials.

Population Pharmacokinetics of Docetaxel, Paclitaxel, Doxorubicin and Epirubicin in Pregnant Women with Cancer: A Study from the International Network of Cancer, Infertility and Pregnancy (INCIP)

BACKGROUND

Based on reassuring short-term foetal and maternal safety data, there is an increasing trend to administer chemotherapy during the second and third trimesters of pregnancy. The pharmacokinetics (PK) of drugs might change as a result of several physiological changes that occur during pregnancy, potentially affecting the efficacy and safety of chemotherapy.

OBJECTIVE

With this analysis, we aimed to quantitatively describe the changes in the PK of docetaxel, paclitaxel, doxorubicin and epirubicin in pregnant women compared with non-pregnant women.

METHODS

PK data from 9, 20, 22 and 16 pregnant cancer patients from the International Network of Cancer, Infertility and Pregnancy (INCIP) were available for docetaxel, paclitaxel, doxorubicin and epirubicin, respectively. These samples were combined with available PK data from non-pregnant patients. Empirical non-linear mixed-effects models were developed, evaluating fixed pregnancy effects and gestational age as covariates.

RESULTS

Overall, 82, 189, 271, and 227 plasma samples were collected from pregnant patients treated with docetaxel, paclitaxel, doxorubicin and epirubicin, respectively. The plasma PK data were adequately described by the respective models for all cytotoxic drugs. Typical increases in central and peripheral volumes of distribution of pregnant women were identified for docetaxel, paclitaxel, doxorubicin and epirubicin. Additionally, docetaxel, doxorubicin and paclitaxel clearance were increased in pregnant patients, resulting in lower exposure in pregnant women compared with non-pregnant patients.

CONCLUSION

Given the interpatient variability, the identified pregnancy-induced changes in PK do not directly warrant dose adjustments for the studied drugs. Nevertheless, these results underscore the need to investigate the efficacy of chemotherapy, when administered during pregnancy.

The Influence of Body Composition on the Systemic Exposure of Paclitaxel in Esophageal Cancer Patients

Changes in body composition are associated with chemotherapy-related toxicities and effectiveness of treatment. It is hypothesized that the pharmacokinetics (PK) of chemotherapeutics may depend on body composition. The effects of body composition on the variability of paclitaxel PK were studied in patients with esophageal cancer. Skeletal muscle index (SMI), visceral adipose tissue (VAT), and skeletal muscle density (SMD) were measured at the third lumbar vertebra on computed tomography (CT) scans performed before treatment. Paclitaxel PK data were collected from a prospective study performed between May 2004 and January 2014. Non-linear mixed-effects modeling was used to fit paclitaxel PK profiles and evaluate the covariates body surface area (BSA), SMI, VAT, and SMD using a significance threshold of p < 0.001. Paclitaxel was administered to 184 patients in a dose range of 50 to 175 mg/m². Median BSA was 1.98 m² (range of 1.4 to 2.8 m²). SMI, VAT, and SMD were not superior to BSA in predicting paclitaxel PK. The additive value of SMI, VAT, and SMD to BSA was also negligible. We did not find evidence that paclitaxel dosing could be further optimized by correcting for SMI, VAT, or SMD.

Does Older Age Lead to Higher Risk for Neutropenia in Patients Treated with Paclitaxel?

PURPOSE

There is ongoing concern regarding increased toxicity from paclitaxel in elderly patients, particularly of severe neutropenia. Yet, data so far is controversial and this concern is not supported by a clinically relevant age-dependent difference in pharmacokinetics (PK) of paclitaxel. This study assessed whether age is associated with increased risk for paclitaxel-induced neutropenia.

METHODS

Paclitaxel plasma concentration-time data, pooled from multiple different studies, was combined with available respective neutrophil count data during the first treatment cycle. Paclitaxel pharmacokinetic-pharmacodynamic (PK-PD) data was modeled using a non-linear mixed effects approach and a semiphysiological neutropenia model, where systemic paclitaxel exposure was linked to reduced proliferation of neutrophils. The impact of age was evaluated on relevant variables in the model, using a significance threshold of p < 0.005.

RESULTS

Paclitaxel PK-PD data was evaluated from 300 patients, with a median age of 65 years (range 23-84 years), containing 116 patients ≥70 years (39%). First cycle neutrophil counts were adequately described by a threshold effect model of paclitaxel on the proliferation rate of neutrophils. Age as a continuous or dichotomous variable (≥70 versus <70 years) did not significantly impact sensitivity of the bone marrow to paclitaxel nor the average maturation time of neutrophils (both p > 0.005), causing a decline in the respective interindividual variability of <1%.

CONCLUSION

Results from this large retrospective patient cohort do not suggest elderly patients to be at an increased risk of developing paclitaxel-associated neutropenia during the first treatment cycle. Reflexive dose reductions of paclitaxel in elderly patients are unlikely to improve the risk of severe neutropenia and may be deleterious.