Pegfilgrastim for the prevention of chemotherapy-induced febrile neutropenia in patients with solid tumors

Neutrophil diversity and function in health and disease

Neutrophils, the most abundant type of granulocyte, are widely recognized as one of the pivotal contributors to the acute inflammatory response. Initially, neutrophils were considered the mobile infantry of the innate immune system, tasked with the immediate response to invading pathogens. However, recent studies have demonstrated that neutrophils are versatile cells, capable of regulating various biological processes and impacting both human health and disease. Cytokines and other active mediators regulate the functional activity of neutrophils by activating multiple receptors on these cells, thereby initiating downstream signal transduction pathways. Dysfunctions in neutrophils and disruptions in neutrophil homeostasis have been implicated in the pathogenesis of numerous diseases, including cancer and inflammatory disorders, often due to aberrant intracellular signaling. This review provides a comprehensive synthesis of neutrophil biological functions, integrating recent advancements in this field. Moreover, it examines the biological roles of receptors on neutrophils and downstream signaling pathways involved in the regulation of neutrophil activity. The pathophysiology of neutrophils in numerous human diseases and emerging therapeutic approaches targeting them are also elaborated. This review also addresses the current limitations within the field of neutrophil research, highlighting critical gaps in knowledge that warrant further investigation. In summary, this review seeks to establish a comprehensive and multidimensional model of neutrophil regulation, providing new perspectives for potential clinical applications and further research.

Bcl-xL targeting eliminates ageing tumor-promoting neutrophils and inhibits lung tumor growth

Elevated peripheral blood and tumor-infiltrating neutrophils are often associated with a poor patient prognosis. However, therapeutic strategies to target these cells are difficult to implement due to the life-threatening risk of neutropenia. In a genetically engineered mouse model of lung adenocarcinoma, tumor-associated neutrophils (TAN) demonstrate tumor-supportive capacities and have a prolonged lifespan compared to circulating neutrophils. Here, we show that tumor cell-derived GM-CSF triggers the expression of the anti-apoptotic Bcl-xL protein and enhances neutrophil survival through JAK/STAT signaling. Targeting Bcl-xL activity with a specific BH3 mimetic, A-1331852, blocked the induced neutrophil survival without impacting their normal lifespan. Specifically, oral administration with A-1331852 decreased TAN survival and abundance, and reduced tumor growth without causing neutropenia. We also show that G-CSF, a drug used to combat neutropenia in patients receiving chemotherapy, increased the proportion of young TANs and augmented the anti-tumor effect resulting from Bcl-xL blockade. Finally, our human tumor data indicate the same role for Bcl-xL on pro-tumoral neutrophil survival. These results altogether provide preclinical evidence for safe neutrophil targeting based on their aberrant intra-tumor longevity.

Cost comparison of filgrastim versus pegfilgrastim and pegfilgrastim biosimilars for inpatient prophylaxis of febrile neutropenia

INTRODUCTION

The Ohio State University Comprehensive Cancer Center (The James) uses daily subcutaneous filgrastim as the inpatient granulocyte colony-stimulating factor of choice. The coordination of care associated with filgrastim can often be a barrier to patient discharge. The purpose of this study was to compare the inpatient cost of daily filgrastim to single dose pegfilgrastim and biosimilars.

METHODS

Adult patients admitted to The James who received at least one dose of filgrastim between June 1, 2021 and August 31, 2021 were retrospectively identified. This study compared the inpatient cost of filgrastim and biosimilars associated with one chemotherapy cycle to the potential inpatient cost of pegfilgrastim and biosimilars based on average sales price (ASP). Additionally, the number and duration of discharge prescriptions for filgrastim was determined.

RESULTS

Of the 44 unique patient encounters that met inclusion criteria, 19 received 300-mcg doses of filgrastim and 25 received 480-mcg doses. The median number of doses administered per admission was eight. If each of these patients were to instead receive the most inexpensive biosimilar, pegfilgrastim reference product, the cost would be 216% higher than with filgrastim-sndz. At discharge, 15 patients (34%) received a prescription for filgrastim to be continued for a median duration of 6 days.

CONCLUSION

Based on ASP, pegfilgrastim was more costly than filgrastim. Potential rebates and negotiation power may alter the financial outlook of adding pegfilgrastim to inpatient formulary. Exploration of delays in discharge due to insurance coordination for filgrastim continuation in the outpatient setting may also impact formulary decisions.

Effects of Prophylactic Administration of Granulocyte Colony-Stimulating Factor on Peripheral Leukocyte and Neutrophil Counts Levels After Chemotherapy in Patients With Early-Stage Breast Cancer: A Retrospective Cohort Study

Background

Both chemotherapy-induced neutropenia (CIN) and febrile neutropenia (FN) frequently occur and can lead to dose-limiting toxicity and even fatal chemotherapy side effects. The prophylactic use of recombinant human granulocyte colony-stimulating factor (rhG-CSF), including pegylated rhG-CSF (PEG-rhG-CSF), significantly reduces the risks of CIN and FN during chemotherapy in early-stage breast cancer (ESBC) patients. However, whether the prophylactic use of granulocyte colony-stimulating factor (G-CSF), especially PEG-rhG-CSF, can influence white blood cell (WBC) counts and absolute neutrophil counts (ANCs) after finishing the chemotherapy remains unknown. Therefore, exploring the development and recovery tendency of WBC counts and ANCs during and after chemotherapy is crucial.

Objective

We aimed to investigate the variation tendency and recovery of WBC counts and ANCs during and after chemotherapy and evaluate the independent factors influencing leukopenia and neutropenia lasting longer after chemotherapy. We also aimed to provide individualized prophylactically leukocyte elevation therapy for breast cancer patients.

Methods

This single-center retrospective cohort study evaluated 515 ESBC patients who received rhG-CSF or PEG-G-CSF for prophylaxis after adjuvant or neoadjuvant chemotherapy. Blood test reports were analyzed during chemotherapy, and on a 12-month follow-up period after finishing the chemotherapy. The WBC counts and ANCs were measured to assess their variation tendency characteristics and to identify independent factors that influenced the occurrence of leukopenia and neutropenia lasting longer than 12 months after chemotherapy.

Results

Prophylaxis with rhG-CSF or PEG-rhG-CSF kept the mean values of WBC counts and ANCs within the normal range during chemotherapy, but a significant difference in WBC levels was detected before the end of the last chemotherapy compared to the prechemotherapy period (baseline) (p < 0.001). During the 12-month follow-up after the end of the last chemotherapy, WBC counts and ANCs gradually recovered, but the group that used only PEG-rhG-CSF (long-acting group, p _WBC = 0.012) or rhG-CSF (short-acting group, p _WBC = 0.0005) had better leukocyte elevation effects than the mixed treatment group (PEG-rhG-CSF mixed rhG-CSF). Besides, the short-acting group had a better neutrophil elevation effect than the longer-acting (p _ANC = 0.019) and mixed (p _ANC = 0.002) groups. Leukopenia was still present in 92 (17.9%) patients and neutropenia in 63 (12.2%) 12 months after the end of the last chemotherapy. The duration of leukopenia over 12 months was closely associated with the baseline WBC level (p < 0.001), G-CSF types (p = 0.027), and surgical method (p = 0.041). Moreover, the duration of neutropenia over 12 months was closely related to the baseline ANC (p < 0.001), G-CSF types (p = 0.043), and molecular typing (p = 0.025).

Conclusion

The prophylactic application of G-CSF effectively stabilized the WBC counts and ANCs during chemotherapy in ESBC patients. Nevertheless, the recovery of WBC counts and ANCs after chemotherapy varied between different G-CSF treatment groups. The risk of leukopenia and neutropenia persisting for more than 12 months after chemotherapy was associated with G-CSF types, the baseline level of WBC count/ANCs, surgical method, and molecular typing.

Biosimilar Pegfilgrastim: Improving Access and Optimising Practice to Supportive Care that Enables Cure

Febrile neutropenia (FN) is a serious complication of chemotherapy, which can cause significant morbidity and mortality, result in dose delays and reductions and, ultimately, reduce cancer survival. Over the past decade, the availability of biosimilar filgrastim (short-acting granulocyte colony-stimulating factor [G-CSF]) has transformed patient access, with clear evidence of clinical benefit at preventing FN at reduced costs. In 2019, seven biosimilar pegfilgrastims (long-acting G-CSFs) were licensed, creating optimal market conditions and choice for prescribers. FN affects up to 117 per 1000 cancer patients, with mortality rates in the range of 2–21%. By reducing FN incidence and improving chemotherapy relative dose intensity (RDI), G-CSF has been associated with a 3.2% absolute survival benefit. Guidelines recommend primary prophylaxis and that filgrastim be administered for 10–14 days, while pegfilgrastim is administered once per cycle. When taken according to the guidelines, pegfilgrastim and filgrastim are equally effective. However, in routine clinical practice, filgrastim is often under-dosed (< 7 days) and has been shown to be inferior to pegfilgrastim at reducing FN incidence, hospitalisations and maintaining RDI. Once-per-cycle administration with pegfilgrastim might also aid patient adherence. The introduction of biosimilar pegfilgrastim should instigate a rethink of neutropenia management. Biosimilar pegfilgrastim offers countries using biosimilar filgrastim opportunities to improve adherence and thus cancer survival, whilst offering economic benefits for countries using reference pegfilgrastim. These benefits can be realised in full if biosimilar pegfilgrastim becomes part of routine clinical practice supported by drug and therapeutic committees implementing guidelines with multidisciplinary support in the hospital.

Contrasting Immunopathogenic and Therapeutic Roles of Granulocyte Colony-Stimulating Factor in Cancer

Tumor cells are particularly adept at exploiting the immunosuppressive potential of neutrophils as a strategy to achieve uncontrolled proliferation and spread. Recruitment of neutrophils, particularly those of an immature phenotype, known as granulocytic myeloid-derived suppressor cells, is achieved via the production of tumor-derived granulocyte colony-stimulating factor (G-CSF) and neutrophil-selective chemokines. This is not the only mechanism by which G-CSF contributes to tumor-mediated immunosuppression. In this context, the G-CSF receptor is expressed on various cells of the adaptive and innate immune systems and is associated with induction of T cell polarization towards the Th2 and regulatory T cell (Treg) phenotypes. In contrast to the potentially adverse effects of sustained, endogenous production of G-CSF by tumor cells, stringently controlled prophylactic administration of recombinant (r) G-CSF is now a widely practiced strategy in medical oncology to prevent, and in some cases treat, chemotherapy-induced severe neutropenia. Following an overview of the synthesis, structure and function of G-CSF and its receptor, the remainder of this review is focused on: (i) effects of G-CSF on the cells of the adaptive and innate immune systems; (ii) mechanisms by which this cytokine promotes tumor progression and invasion; and (iii) current clinical applications and potential risks of the use of rG-CSF in medical oncology.

Is PEGylated G-CSF superior to G-CSF in patients with breast cancer receiving chemotherapy? A systematic review and meta-analysis

BACKGROUND

PEGylated granulocyte colony-stimulating factor (G-CSF) is a safe alternative to G-CSF to improve chemotherapy-induced neutropenia (CIN). This superiority has resulted in its increased use by physicians; however, the superiority of PEGylated G-CSF for CIN in breast cancer has not been conclusively determined.

OBJECTIVES

To assess the superiority of PEGylated G-CSF for CIN in breast cancer in terms of effectiveness and safety via a systematic review and meta-analysis.

METHODS

A literature search in PubMed, Embase, Cochrane Library, and Web of Science was performed for eligible studies published from database inception to December 2019. All studies comparing PEGylated G-CSF and G-CSF for CIN of breast cancer were reviewed. After literature selection, data extraction and quality assessment were performed by two reviewers independently. Meta-analysis was conducted using Revman, version 5.2.

RESULTS

Nine randomized controlled trials were finally identified. The publication bias of these studies was acceptable. For the endpoint of effectiveness, analysis of the incidence/duration of grade ≥ 3 neutropenia, the duration of grade 4 neutropenia, the incidence of febrile neutropenia (FN), and the time to absolute neutrophil count recovery showed no advantage of PEGylated G-CSF over G-CSF for CIN of breast cancer (P > 0.05), with the premise of a sufficient dose of G-CSF according to the guidelines. No significant differences in grade 4 adverse events were observed between the groups (P = 0.29), and PEGylated G-CSF did not increase the incidence of skeletal and/or muscle pain compared with G-CSF (P = 0.32).

CONCLUSION

PEGylated G-CSF was as effective and safe as G-CSF to reduce CIN in breast cancer but did not show an obvious superiority. However, in clinical practice, PEGylated G-CSF has an obvious advantage in terms of convenience, which could improve patient's quality of life.

Introduction of biosimilar pegfilgrastim in France: Economic analysis of switching from originator

Objectives

To assess the economic impact of introducing biosimilar pegfilgrastim compared to the current standard granulocyte colony-stimulating factor (G-CSF) practice in France.

Methods

A budget impact model was developed to investigate the impact of introducing pegfilgrastim biosimilar over 5 years. The model analysed drug acquisition costs, ambulatory costs, as well as costs associated with poor outcomes, and compared the current standard practice of long-acting and short-acting G-CSF to a revised practice including pegfilgrastim biosimilar in addition to standard practice treatments. The cost of switching to pegfilgrastim biosimilar, within a pharmacy setting, was analysed within the model using data from a survey of French pharmacists.

Results

The budget impact model calculated a cost saving of €51,007,531 over 5 years switching from the current standard practice to pegfilgrastim biosimilar. A sensitivity analysis accounting for variation in pegfilgrastim biosimilar uptake of 1) 15% in year 1 and 1% in years 2–5 and 2) 15% in years 1–5, estimated savings ranging between €29,377,784 and €79,847,194, respectively. A further analysis predicted cost savings of €287,344,835 over 5 years with the extension of pegfilgrastim biosimilar, at an uptake of 15% in year 1 and 7% in years 2–4, to both long-acting and short-acting G-CSF groups compared to unchanged current practice.

Conclusions

The introduction of pegfilgrastim biosimilar will help to reduce cost and alleviate some of the financial pressure on the French healthcare system.

Retrospective study evaluating the safety of administering pegfilgrastim on the final day of 5-fluorouracil continuous intravenous infusion

BACKGROUND

Pegfilgrastim, a long-acting granulocyte-colony-stimulating factor used to prevent neutropenia, is not indicated for administration within 24 h of completion of chemotherapy. The safety of administering pegfilgrastim in gastrointestinal cancer chemotherapy regimens containing continuous intravenous infusion of 5-fluorouracil (5-FUCI) on the day of completion of 5-fluorouracil has not been adequately studied.

METHODS

An institutional review board-approved retrospective analysis of patients with a gastrointestinal malignancy receiving pegfilgrastim on the final day of 5-FUCI was conducted. The primary end point was to determine the incidence of grade 3 and grade 4 neutropenia and febrile neutropenia when pegfilgrastim was administered on the final day of 5-FUCI. The secondary endpoint was to determine rate of dose reductions and treatment delays.

RESULTS

A total of 300 patients were reviewed from January 2010 to May 2017. The most common cancers were colorectal (25%) and pancreatic (60%), with 77% of patients having late stage disease. The risk of a patient developing grade 3 neutropenia was 0.010 (95% CI 0.002-0.029) and grade 4 neutropenia was 0.007 (95% CI 0.001-0.024). The risk of febrile neutropenia was 0.007 (95% CI 0.001-0.024). The risks of treatment delay and treatment reduction were 0.013 (95% CI 0.004-0.034) and 0.010 (95% CI 0.002-0.029), respectively.

CONCLUSION

The low risk of grade 3 and grade 4 neutropenia, febrile neutropenia, as well as dose delays and/or reduction suggests that pegfilgrastim can be administered on the final day of 5-FUCI. Limitations of this study were that it was retrospective in nature and was conducted at a single institution.

Rehabilitation for Rhabdomyolysis Associated With Breast Cancer Treatment

Rhabdomyolysis can result in pain, physical limitations and may require hospitalization for medical management; however, little evidence has been reported on the efficacy of physical therapy (PT) interventions for this condition. Additionally, a review of literature on occurrences of rhabdomyolysis associated with cancer treatments yielded limited results. The purpose of this case report was to describe the acute and inpatient rehabilitation (IPR) examination, interventions, and outcomes for a patient with breast cancer and rhabdomyolysis. The patient was a 57-year-old female with a history of recurrent breast cancer who presented to the hospital with a chief complaint of bilateral thigh pain and weakness after the second cycle of chemotherapy and was diagnosed with rhabdomyolysis. After initially declining PT treatment during her first hospitalization, the patient was readmitted after a fall at home. She was hospitalized for 14 days with a transfer to IPR. The patient received a total of 12 days of PT (two acute care visits and 10 IPR visits) that included patient education, neuromuscular re-education, therapeutic exercise, and gait training. The patient was discharged home at a modified independent level with improvements in pain from 8/10 to 0/10 on the Numeric Pain Rating Scale. Functionally, she improved from ambulating 20 feet (6.1 m) to 600 feet (183 m); her Timed Up and Go score improved from 62 seconds to 10 seconds. Finally, her Berg Balance Scale improved from 31/56 to 55/56. Data from this case study suggest that PT management appears to improve functional outcomes for individuals diagnosed with rhabdomyolysis while undergoing chemotherapy, however, a holistic approach was necessary for progress to educate her on the importance of participation in PT with this condition. Further research is required to explore factors that influence rhabdomyolysis in the presence of chemotherapy as well as the recommended rehabilitation program for rhabdomyolysis.

Preformulation Studies and Enabling Formulation Selection for an Insoluble Compound at Preclinical Stage-From In Vitro, In Silico to In Vivo

The objective of this work was to identify an enabling formulation for an insoluble compound ZL006 with potency of boosting leukocytes after chemotherapy. The low oral bioavailability (<1%) of its conventional suspension was the hurdle for the preclinical evaluation via oral administration. Preformulation studies including physical form screening and physicochemical properties determination were performed. Polymorphism was observed, and the more thermodynamically stable form was selected for further studies. ZL006 showed certain supersaturation solubility, although the thermodynamic solubility in FaSSIF was low, which indicated the supersaturating formulation might work. Parameter sensitivity analysis by in silico simulation predicted that in vivo exposure was sensitive to solubility, while particle size reduction would have limited impact on exposure. Based on in silico prediction and the understanding of the molecule from preformulation studies, solid dispersion approach was selected. A preliminary dose escalation pharmacokinetic study in rats demonstrated that in vivo exposure increased in dose-proportional manner from 12.5 mg/kg to 50 mg/kg with around 50% oral bioavailability after oral dosing of the solid dispersion. This work showed that combination of preformulation studies and in silico simulation could efficiently guide the selection of enabling formulation, which could save resources at preclinical stage.

Use and effectiveness of pegfilgrastim prophylaxis in US clinical practice:a retrospective observational study

BACKGROUND

Febrile neutropenia (FN) is a serious complication of myelosuppressive chemotherapy. Clinical practice guidelines recommend routine prophylactic coverage with granulocyte colony-stimulating factor (G-CSF)-such as pegfilgrastim-for most patients receiving chemotherapy with an intermediate to high risk for FN. Patterns of pegfilgrastim prophylaxis during the chemotherapy course and associated FN risks in US clinical practice have not been well characterized.

METHODS

A retrospective cohort design and data from two commercial healthcare claims repositories (01/2010-03/2016) and Medicare Claims Research Identifiable Files (01/2007-09/2015) were employed. Study population included patients who had non-metastatic breast cancer or non-Hodgkin's lymphoma and received intermediate/high-risk regimens. Pegfilgrastim prophylaxis use and FN incidence were ascertained in each chemotherapy cycle, and all cycles were pooled for analyses. Adjusted odds ratios for FN were estimated for patients who did versus did not receive pegfilgrastim prophylaxis in that cycle.

RESULTS

Study population included 50,778 commercial patients who received 190,622 cycles of chemotherapy and 71,037 Medicare patients who received 271,944 cycles. In cycle 1, 33% of commercial patients and 28% of Medicare patients did not receive pegfilgrastim prophylaxis, and adjusted odds of FN were 2.6 (95% CI 2.3-2.8) and 1.6 (1.5-1.7), respectively, versus those who received pegfilgrastim prophylaxis. In cycle 2, 28% (commercial) and 26% (Medicare) did not receive pegfilgrastim prophylaxis; corresponding adjusted FN odds were comparably elevated (1.9 [1.6-2.2] and 1.6 [1.5-1.8]). Results in subsequent cycles were similar. Across all cycles, 15% of commercial patients and 23% of Medicare patients did not receive pegfilgrastim prophylaxis despite having FN in a prior cycle, and prior FN increased odds of subsequent FN by 2.1-2.4 times.

CONCLUSIONS

Notwithstanding clinical practice guidelines, a large minority of patients did not receive G-CSF prophylaxis, and FN incidence was substantially higher among this subset of the population. Appropriate use of pegfilgrastim prophylaxis may reduce patient exposure to this potentially fatal but largely preventable complication of myelosuppressive chemotherapy.

A randomized multicenter phase II trial of mecapegfilgrastim single administration versus granulocyte colony-stimulating growth factor on treating chemotherapy-induced neutropenia in breast cancer patients

Background

This study aimed to evaluate the efficacy and safety of mecapegfilgrastim (HHPG-19K) with different doses compared to granulocyte colony-stimulating growth factor (G-CSF) in treating chemotherapy-induced neutropenia in breast cancer patients.

Methods

A total of 182 breast cancer patients were enrolled in this multi-center, randomized, phase II trial and developed neutropenia after first cycle chemotherapy. Patients were then assigned as 1:1:1 ratio to receive 100 µg/kg HHPG-19K single injection (HHPG-19K-N group), 150 µg/kg HHPG-19Ksingle injection (HHPG-19K-H group) and 5 µg/kg G-CSF daily injection (G-CSF group) at day 3 of the second cycle (cycle 2) chemotherapy. The primary endpoint was incidence of grade ≥3 neutropenia during cycle 2. Study drug-related adverse events during cycle 2 were recorded for safety assessment.

Results

During cycle 2 chemotherapy, both HHPG-19K-N and HHPG-19K-H groups exhibited lower incidence of grade ≥3 neutropenia compared with G-CSF group, while no difference was observed between HHPG-19K-N and HHPG-19K-H groups. Also, better outcomes were observed in HHPG-19K-N and HHPG-19K-H groups compared with G-CSF group regarding to grade 4 neutropenia, duration of grade ≥3 neutropenia, duration of grade 4 neutropenia, incidence of febrile neutropenia (FN) and rescue application of G-CSF, time to ANC recovery, while no difference of these outcomes between HHPG-19K-N and HHPG-19K-H groups was observed. For safety analysis, the incidences of hematologic and non-hematologic adverse events were similar among the 3 groups.

Conclusions

HHPG-19K presents with better clinical efficacy as well as equal tolerance compared with G-CSF in treating chemotherapy-induced neutropenia in breast cancer patients.

Trends in peripheral stem/progenitor cell manipulation and clinical application

Transplants using peripheral blood hemopoietic stem/progenitor (PBHS) cells are widely performed for the treatment of patients with hematologic disorders in routine practice and clinical trials. Although the process from mobilization to infusion of PBHS cells has been mostly established, optimal conditions for each process remain undetermined. Adverse reactions caused by PBHS cell infusions have not been systematically recorded. In transplants using PBHS cells, a number of problems still exist. In this section, the current status of and future perspectives regarding PBHS cells are described.

Model-based optimization of G-CSF treatment during cytotoxic chemotherapy

PURPOSE

Although G-CSF is widely used to prevent or ameliorate leukopenia during cytotoxic chemotherapies, its optimal use is still under debate and depends on many therapy parameters such as dosing and timing of cytotoxic drugs and G-CSF, G-CSF pharmaceuticals used and individual risk factors of patients.

METHODS

We integrate available biological knowledge and clinical data regarding cell kinetics of bone marrow granulopoiesis, the cytotoxic effects of chemotherapy and pharmacokinetics and pharmacodynamics of G-CSF applications (filgrastim or pegfilgrastim) into a comprehensive model. The model explains leukocyte time courses of more than 70 therapy scenarios comprising 10 different cytotoxic drugs. It is applied to develop optimized G-CSF schedules for a variety of clinical scenarios.

RESULTS

Clinical trial results showed validity of model predictions regarding alternative G-CSF schedules. We propose modifications of G-CSF treatment for the chemotherapies 'BEACOPP escalated' (Hodgkin's disease), 'ETC' (breast cancer), and risk-adapted schedules for 'CHOP-14' (aggressive non-Hodgkin's lymphoma in elderly patients).

CONCLUSIONS

We conclude that we established a model of human granulopoiesis under chemotherapy which allows predictions of yet untested G-CSF schedules, comparisons between them, and optimization of filgrastim and pegfilgrastim treatment. As a general rule of thumb, G-CSF treatment should not be started too early and patients could profit from filgrastim treatment continued until the end of the chemotherapy cycle.

Coating Matters: Review on Colloidal Stability of Nanoparticles with Biocompatible Coatings in Biological Media, Living Cells and Organisms

Within the last two decades, the field of nanomedicine has not developed as successfully as has widely been hoped for. The main reason for this is the immense complexity of the biological systems, including the physico-chemical properties of the biological fluids as well as the biochemistry and the physiology of living systems. The nanoparticles' physicochemical properties are also highly important. These differ profoundly from those of freshly synthesized particles when applied in biological/living systems as recent research in this field reveals. The physico-chemical properties of nanoparticles are predefined by their structural and functional design (core and coating material) and are highly affected by their interaction with the environment (temperature, pH, salt, proteins, cells). Since the coating material is the first part of the particle to come in contact with the environment, it does not only provide biocompatibility, but also defines the behavior (e.g. colloidal stability) and the fate (degradation, excretion, accumulation) of nanoparticles in the living systems. Hence, the coating matters, particularly for a nanoparticle system for biomedical applications, which has to fulfill its task in the complex environment of biological fluids, cells and organisms. In this review, we evaluate the performance of different coating materials for nanoparticles concerning their ability to provide colloidal stability in biological media and living systems.