The pharmacokinetics and metabolism of ifosfamide during bolus and infusional administration: a randomized cross-over study

Assessment of Risk of Bias in Osteosarcoma and Ewing's Sarcoma Randomized Controlled Trials: A Systematic Review

Aim: The aim of this study was to systematically assess the risk of bias in osteosarcoma and Ewing’s sarcoma (ES) randomized controlled trials (RCT) and to examine the relationships between bias and conflict of interest/industry sponsorship. Methods: An OVID-MEDLINE search was performed (1976–2019). Using the Cochrane Collaboration guidelines, two reviewers independently assessed the prevalence of risk of bias in different RCT design domains. The relationship between conflicts of interest and industry funding with the frequency of bias was examined. Results: 73 RCTs met inclusion criteria. Prevalence of low-risk bias domains was 47.3%, unclear-risk domains 47.8%, and 4.9% of the domains had a high-risk of bias. Domains with the highest risk of bias were blinding of participants/personnel and outcome assessors, followed by randomization and allocation concealment. Overtime, frequency of unclear-risk of bias domains decreased (χ² = 5.32, p = 0.02), whilst low and high-risk domains increased (χ² = 8.13, p = 0.004). Studies with conflicts of interest and industry sponsorships were 4.2 and 3.1 times more likely to have design domains with a high-risk of bias (p < 0.05). Conclusion: This study demonstrates that sources of potential bias are prevalent in both osteosarcoma and ES RCTs. Studies with financial conflicts of interest and industry sponsors were significantly more likely to have domains with a high-risk of bias. Improvements in reporting and adherence to proper methodology will reduce the risk of bias and improve the validity of the results of RCTs in osteosarcoma and ES.

Continuous-infusion ifosfamide and doxorubicin combination as second-line chemotherapy for recurrent or refractory osteosarcoma patients in China: a retrospective study

OBJECTIVE

The aim of this retrospective study was to evaluate the feasibility and efficacy of response to continuous-infusion ifosfamide and doxorubicin combination as second-line chemotherapy for patients with recurrent or refractory osteosarcoma.

MATERIALS AND METHODS

Eighteen recurrent or refractory osteosarcoma patients who were treated with continuous-infusion ifosfamide and doxorubicin combination between May 1999 and April 2011 were included in the analysis. Ifosfamide at 12 g/m2 was administered by intravenous continuous infusion over 3 days, and doxorubicin 60 mg/m2 was administered as an intravenous bolus injection on day 1. The combination therapy was repeated every 3 weeks. Treatment was continued until evidence of disease progression or unacceptable toxicity.

RESULTS

The patients (ages 7-53 years) received a total of 42 cycles of chemotherapy (median: 2 courses; range: 2-5 courses). The overall response rate was 0% and the disease control rate was 22.3%, with four patients having stable disease. The median time to progression and overall survival time were 2 months (range: 2-5 months) and 9 months (range: 3-29 months), respectively. Major severe toxicities were leucopenia 7 (38.9%), nausea and vomiting 3 (16.7%) and alopecia 9 (50%). There were no treatment-related deaths.

CONCLUSIONS

In our experience, continuous-infusion ifosfamide and doxorubicin combination therapy at this dosage and schedule was found to be well tolerated and moderate effective, which could be considered as salvage therapy for patients with recurrent or refractory osteosarcoma. Further assessment is necessary to confirm the safety and efficacy of this treatment.

Electrochemical detection of anti-breast-cancer agents in human serum by cytochrome P450-coated carbon nanotubes

We report on the electrochemical detection of anti-cancer drugs in human serum with sensitivity values in the range of 8–925 nA/μM. Multi-walled carbon nanotubes were functionalized with three different cytochrome P450 isoforms (CYP1A2, CYP2B6, and CYP3A4). A model used to effectively describe the cytochrome P450 deposition onto carbon nanotubes was confirmed by Monte Carlo simulations. Voltammetric measurements were performed in phosphate buffer saline (PBS) as well as in human serum, giving well-defined current responses upon addition of increasing concentrations of anti-cancer drugs. The results assert the capability to measure concentration of drugs in the pharmacological ranges in human serum. Another important result is the possibility to detect pairs of drugs present in the same sample, which is highly required in case of therapies with high side-effects risk and in anti-cancer pharmacological treatments based on mixtures of different drugs. Our technology holds potentials for inexpensive multi-panel drug-monitoring in personalized therapy.

Prolonged 14-day continuous infusion of high-dose ifosfamide with an external portable pump: feasibility and efficacy in refractory pediatric sarcoma

BACKGROUND

Ifosfamide is currently used to treat pediatric sarcomas and increasing its dosage may be associated with a better response rate. Prolonged continuous infusion seems an attractive administration modality.

METHODS

Ifosfamide 14 g/m(2) (with mesna 14 g/m(2)) was administered through an ambulatory portable pump over 14 days as a continuous infusion, starting every 3 weeks, in 14 patients with relapsing sarcomas. No growth factors were given.

RESULTS

Acute grade 3 hematological toxicity was observed in only 13/66 cycles and red cell transfusions were given in two patients. Hematuria and dysuria occurred in three cases. The response rate was: five partial responses, five stable disease. The median time to progression was 3 months (range: 2-19 months). The best response rate was seen for synovial sarcoma and Ewing sarcoma.

CONCLUSION

Prolonged 14-day continuous infusion of high-dose ifosfamide is well tolerated. Potentially interesting preliminary responses in pediatric patients already treated with ifosfamide are reported.

Evaluation of dose-intense Ifosfamide, with and without edatrexate, in adults with sarcoma

Purpose. To define the maximally tolerated dose (MTD) of ifosfamide when given with G-CSF on an every other week schedule, and to define the MTD of edatrexate that can be given every two weeks with an intense schedule of ifosfamide.

Patients and Methods. Forty-one patients with metastatic or unresectable, locally advanced sarcoma participated in this 2-step phase I trial.The starting dose of ifosfamide was 10 gm/m² given by continuous intravenous infusion over 4 days every 2 weeks.When the MTD was defined, edatrexate, beginning at a dose of 40 mg/m² intravenously every 2 weeks was added in subsequent cohorts of patients.

Results. Myelosuppression was the most prominent toxicity. Fatigue, nausea, and vomiting were observed in the majority of patients. Ifosfamide 12 gm/m² given every 2 weeks approached or exceeded the MTD. Edatrexate 100 mg/m² could be given safety as an intravenous bolus with ifosfamide 10 gm/m² every 2 weeks. Therapeutic responses were observed in patients with measurable disease.

Conclusions. This study demonstrates the feasibility of administering a dose-intense schedule of ifosfamide alone or ifosfamide with edatrexate that might be applied in the adjuvant or neo-adjuvant setting.

The pharmacologic basis of ifosfamide use in adult patients with advanced soft tissue sarcomas

The treatment outcome of patients with locally advanced and metastatic soft tissue sarcomas is poor. Doxorubicin is regarded as standard treatment, but its use is featured by the occurrence of cardiotoxicity. This hinders the administration of this drug at high doses or in combination with, in theory, attractive newly developed targeted drugs, such as vascular endothelial growth factor (VEGF) pathway inhibitors. The combination of doxorubicin and VEGF pathway inhibitors has been shown to yield an unacceptable high rate of cardiomyopathy. Ifosfamide is the only drug that consistently shows response rates comparable to those of doxorubicin. The lack of cardiotoxicity renders this drug a much more attractive alternative than doxorubicin to be explored at high doses or as part of new drug combinations. This review addresses the clinical pharmacology, metabolism, and present role of ifosfamide in the treatment of locally advanced and/or metastatic soft tissue sarcomas, excluding gastrointestinal stromal tumors, the Ewing-like sarcomas, and other small blue round cell tumors. Furthermore, this review focuses on the anticipated growing role of ifosfamide in the development of new treatment strategies.

Assessment of ifosfamide pharmacokinetics, toxicity, and relation to CYP3A4 activity as measured by the erythromycin breath test in patients with sarcoma

BACKGROUND

Ifosfamide is a chemotherapeutic agent that requires cytochrome P450 3A (CYP3A) for bioactivation and metabolism. To the authors' knowledge, the correlation between dose, pharmacokinetics, CYP3A, and toxicity has not been fully evaluated. A randomized Phase II trial was performed on 22 soft tissue sarcoma patients treated with doxorubicin (60 mg/m(2)/cycle) and either high-dose ifosfamide (12 g/m(2)/cycle) or standard-dose ifosfamide (6 g/m(2)/cycle). The pharmacokinetics of ifosfamide and CYP3A measurements observed are reported.

METHODS

Pharmacokinetic parameters for ifosfamide, 2-dichloroethylifosfamide (2-DCE), and 3-dichloroethylifosfamide (3-DCE) were collected after the first ifosfamide infusion in 13 patients. Bayesian designed limited pharmacokinetic data were collected from an additional 41 patients. The erythromycin breath test (ERMBT) was performed on 81 patients as an in vivo phenotypic assessment of CYP3A activity.

RESULTS

Fourteen-hour (peak) plasma levels of ifosfamide, 2-DCE, and 3-DCE were found to correlate strongly with the respective area under the curve (AUC) 0-24 values (r=0.97, 0.94, and 0.95; P<.0001). Patients who experienced a grade 3-4 absolute neutrophil count (ANC), platelet, or creatinine toxicity (using the National Cancer Institute Common Toxicity Criteria [version 2]) were found to have statistically significantly higher median 14-hour plasma levels of ifosfamide, 2-DCE, and 3-DCE compared with patients with grade 0-2 toxicity. ERMBT was not found to correlate with pharmacokinetic parameters of ifosfamide and metabolites or toxicity.

CONCLUSIONS

The 14-hour plasma level of ifosfamide, 2-DCE, and 3-DCE is a simple and appropriate substitute for describing the AUC of ifosfamide after 1 day of a 1-hour to 2-hour infusion of drug. Fourteen-hour plasma levels of ifosfamide and metabolites are useful predictors of neutropenia, thrombocytopenia, and creatinine toxicity. ERMBT was not found to accurately correlate with ifosfamide pharmacokinetics or clinical toxicity.

International Society of Geriatric Oncology (SIOG) recommendations for the adjustment of dosing in elderly cancer patients with renal insufficiency

A SIOG taskforce was formed to discuss best clinical practice for elderly cancer patients with renal insufficiency. This manuscript outlines recommended dosing adjustments for cancer drugs in this population according to renal function. Dosing adjustments have been made for drugs in current use which have recommendations in renal insufficiency and the elderly, focusing on drugs which are renally eliminated or are known to be nephrotoxic. Recommendations are based on pharmacokinetic and/or pharmacodynamic data where available. The taskforce recommend that before initiating therapy, some form of geriatric assessment should be conducted that includes evaluation of comorbidities and polypharmacy, hydration status and renal function (using available formulae). Within each drug class, it is sensible to use agents which are less likely to be influenced by renal clearance. Pharmacokinetic and pharmacodynamic data of anticancer agents in the elderly are needed in order to maximise efficacy whilst avoiding unacceptable toxicity.

Variations in schedules of ifosfamide administration: a better understanding of its implications on pharmacokinetics through a randomized cross-over study

PURPOSE

The metabolism of ifosfamide is a delicate balance between a minor activation pathway (4-hydroxylation) and a mainly toxification pathway (N-dechloroethylation), and there remains uncertainty as to the optimal intravenous schedule.

METHODS

This study assesses ifosfamide pharmacokinetics (PK) according to two standard schedules. Using a 1:1 randomized trial design, we prospectively evaluated ifosfamide PK on two consecutive cycles of 3 g/m2/day for 3 days (9 g/m2/cycle) given in one of two schedules either by continuous infusion (CI) or short (3 h) infusion. Highly sensitive analytical methods allowed determination of concentrations of ifosfamide and the key metabolites 4-hydroxy-ifosfamide, 2- and 3-dechloroethyl-ifosfamide.

RESULTS

Extensive PK analysis was available in 12 patients and showed equivalence between both schedules (3 h versus CI) based on area under the curves (micromol/l x h) for ifosfamide, 4-hydroxy-ifosfamide, 2- and 3-dechloroethyl-ifosfamide (9,379 +/- 2,638 versus 8,307 +/- 1,995, 152 +/- 59 versus 161 +/- 77, 1,441 +/- 405 versus 1,388 +/- 393, and 2,808 +/- 508 versus 2,634 +/- 508, respectively, all P > 0.2). The classical auto-induction of metabolism over the 3 days of infusion was confirmed for both schedules.

CONCLUSION

This study confirms similar PK for both active and toxic metabolites of ifosfamide in adult cancer patients when 9 g/m2 of ifosfamide is administered over 3 days by CI or daily 3-h infusions.

Influence of age upon Ifosfamide-induced nephrotoxicity

BACKGROUND

Ifosfamide-induced nephrotoxicity is well recognized in children, although it has also been reported in adults. Whether ifosfamide nephrotoxicity is more common in children than in adults is not known.

PROCEDURE

Medical records of adults and children diagnosed with sarcoma whom received ifosfamide with a cumulative dose >20 g/m(2) were evaluated. Twenty-five children (</=18-years of age) and 28 adults were identified.

RESULTS

National Cancer Institute Common Toxicity Criteria grade 3-4 ifosfamide-induced nephrotoxicity was present in 24 and 17% of children and adults, respectively (P = 0.58). Cumulative ifosfamide doses were similar between the two populations, with the median (range) of 70.2 g/m(2) (22.4-72) for children and 59 g/m(2) (20.8-146) for adults (P = 0.25). Logistic regression analysis indicated that neither age or cumulative ifosfamide dose were associated with grade 3-4 ifosfamide-induced nephrotoxicity (P = 0.36).

CONCLUSIONS

Children and adults receiving >20 g/m(2) of ifosfamide have similar susceptibility to ifosfamide-induced nephrotoxicity. Factors other than age and cumulative dose should be considered for understanding the inter-individual variation in nephrotoxicity.

Pharmacology of anticancer drugs in the elderly population

Modifications to bodily functions and physiology are known to occur with age. These changes can have a considerable impact on the pharmacokinetic processes of absorption, distribution, metabolism and excretion and the pharmacodynamic properties of administered drugs. For many drugs with a high therapeutic index, this will be clinically unimportant, but for anticancer drugs, which usually have a low therapeutic index, these pharmacological changes can lead to dramatic consequences, such as excessive drug concentrations and unacceptable toxicity, or subtherapeutic drug concentrations and ineffective treatment. Despite the increased susceptibility of the elderly to these changes, doses are rarely adapted on the basis of pharmacokinetics and pharmacodynamics, with the exception of changes secondary to altered renal function. Until recently, only a few large prospective randomised trials have provided evidence-based data for dose adaptations in elderly patients. However, with increasing knowledge of the pharmacokinetics of anticancer drugs, advances in the knowledge of pharmacokinetic behaviour with aging, and documented efficacy and toxicity data in the elderly population, it is possible to highlight aspects of prescribing anticancer drugs in the elderly. In general, and for most drugs, age itself is not a contraindication to full-dose chemotherapy. The main limiting factors are comorbidity and poor functional status, which may be present in a significant number of the elderly population. Elderly patients with cancer are part of the daily practice of oncologists, but currently clinicians can often only estimate whether dose modification is advantageous for the elderly. This review attempts to elucidate the factors that can influence the pharmacokinetics of anticancer drugs frequently used in the elderly, and the clinical or biochemical parameters that form the basis for dose adjustments with age.

Clinical pharmacokinetics and pharmacodynamics of ifosfamide and its metabolites

This review discusses several issues in the clinical pharmacology of the antitumour agent ifosfamide and its metabolites. Ifosfamide is effective in a large number of malignant diseases. Its use, however, can be accompanied by haematological toxicity, neurotoxicity and nephrotoxicity. Since its development in the middle of the 1960s, most of the extensive metabolism of ifosfamide has been elucidated. Identification of specific isoenzymes responsible for ifosfamide metabolism may lead to an improved efficacy/toxicity ratio by modulation of the metabolic pathways. Whether ifosfamide is specifically transported by erythrocytes and which activated ifosfamide metabolites play a key role in this transport is currently being debated. In most clinical pharmacokinetic studies, the phenomenon of autoinduction has been observed, but the mechanism is not completely understood. Assessment of the pharmacokinetics of ifosfamide and metabolites has long been impaired by the lack of reliable bioanalytical assays. The recent development of improved bioanalytical assays has changed this dramatically, allowing extensive pharmacokinetic assessment, identifying key issues such as population differences in pharmacokinetic parameters, differences in elimination dependent upon route and schedule of administration, implications of the chirality of the drug and interpatient pharmacokinetic variability. The mechanisms of action of cytotoxicity, neurotoxicity, urotoxicity and nephrotoxicity have been pivotal issues in the assessment of the pharmacodynamics of ifosfamide. Correlations between the new insights into ifosfamide metabolism, pharmacokinetics and pharmacodynamics will rationalise the further development of therapeutic drug monitoring and dose individualisation of ifosfamide treatment.

Metabolism and pharmacokinetics of oxazaphosphorines

The 2 most commonly used oxazaphosphorines are cyclophosphamide and ifosfamide, although other bifunctional mustard analogues continue to be investigated. The pharmacology of these agents is determined by their metabolism, since the parent drug is relatively inactive. For cyclophosphamide, elimination of the parent compound is by activation to the 4-hydroxy metabolite, although other minor pathways of inactivation also play a role. Ifosfamide is inactivated to a greater degree by dechloroethylation reactions. More robust assay methods for the 4-hydroxy metabolites may reveal more about the clinical pharmacology of these drugs, but at present the best pharmacodynamic data indicate an inverse relationship between plasma concentration of parent drug and either toxicity or antitumour effect. The metabolism of cyclophosphamide is of particular relevance in the application of high dose chemotherapy. The activation pathway of metabolism is saturable, such that at higher doses (greater than 2 to 4 g/m2) a greater proportion of the drug is eliminated as inactive metabolites. However, both cyclophosphamide and ifosfamide also act to induce their own metabolism. Since most high dose regimens require a continuous infusion or divided doses over several days, saturation of metabolism may be compensated for, in part, by auto-induction. Although a quantitative distinction may be made between the cytochrome P450 isoforms responsible for the activating 4-hydroxylation reaction and those which mediate the dechloroethylation reactions, selective induction of the activation pathway, or inhibition of the inactivating pathway, has not been demonstrated clinically. Mathematical models to describe and predict the relative contributions of saturation and autoinduction to the net activation of cyclophosphamide have been developed. However, these require careful validation and may not be applicable outside the exact regimen in which they were derived. A further complication is the chiral nature of these 2 drugs, with some suggestion that one enantiomer may have a favourable profile of metabolism over the other. That the oxazaphosphorines continue to be the subject of intensive investigation over 30 years after their introduction into clinical practice is partly because of their antitumour activity. Further advances in analytical and molecular pharmacological techniques may further optimise their use and allow rational design of more selective analogues.

Ifosfamide in the elderly: clinical considerations for a better drug management

The therapeutic strategy used for elderly affected by malignant neoplasms should take into account the common variables present in oncological patients, and the specific alteration of the elderly metabolism and their possible morbidity. Ifosfamide is an active drug for various tumors with elevated incidence in the elderly. We analyze the principle criteria in the selection of these patients and the alterations of metabolism which correlates to aging with their consequences on the pharmacokinetics of ifosfamide. Finally, we propose clinical guidelines to optimize the use of ifosfamide in elderly patients affected by malignant tumors.

Saturable metabolism of continuous high-dose ifosfamide with mesna and GM-CSF: a pharmacokinetic study in advanced sarcoma patients. Swiss Group for Clinical Cancer Research (SAKK)

BACKGROUND

The aim of this study was to assess the pharmacology, toxicity and activity of high-dose ifosfamide mesna +/- GM-CSF administered by a five-day continuous infusion at a total ifosfamide dose of 12-18 g/m2 in adult patients with advanced sarcomas.

PATIENTS AND METHODS

Between January 1991 and October 1992 32 patients with advanced or metastatic sarcoma were entered the study. Twenty-seven patients were pretreated including twenty-three with prior ifosfamide at less than 8 g/m2 total dose/cycle. In 25 patients (27 cycles) extensive pharmacokinetic analyses were performed.

RESULTS

The area under the plasma concentration-time curve (AUC) for ifosfamide increased linearly with dose while the AUC's of the metabolites measured in plasma by thin-layer chromatography did not increase with dose, particularly that of the active metabolite isophosphoramide mustard. Furthermore the AUC of the inactive carboxymetabolite did not increase with dose. Interpatient variability of pharmacokinetic parameters was high. Dose-limiting toxicity was myelosuppression at 18 g/m2 total dose with grade 4 neutropenia in five of six patients and grade 4 thrombocytopenia in four of six patients. Therefore the maximum tolerated dose was considered to be 18 g/m2 total dose. There was one CR and eleven PR in twenty-nine evaluable patients (overall response rate 41%).

CONCLUSION

Both the activation and inactivation pathways of ifosfamide are non-linear and saturable at high-doses although the pharmacokinetics of the parent drug itself are dose linear. Ifosfamide doses greater than 14-16 g/m2 per cycle appear to result in a relative decrease of the active metabolite isophosphoramide mustard. These data suggest a dose-dependent saturation or even inhibition of ifosfamide metabolism by increasing high dose ifosfamide and suggest the need for further metabolic studies.