Pharmacokinetics of free and total platinum species after rapid and prolonged infusions of cisplatin

Gastrodin alleviates cisplatin nephrotoxicity by inhibiting ferroptosis via the SIRT1/FOXO3A/GPX4 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cisplatin (CP) results in acute kidney injury (AKI) and negatively affects patients' therapy and survival. The dried rhizome of Gastrodia elata Blume has been used to treat clinical kidney diseases. Gastrodin (GAS) is an active ingredient of the G. elata tuber. It is unknown whether GAS can alleviate CP-induced AKI.

AIM OF THE STUDY

This study aimed to investigate whether GAS, an active ingredient of G. elata Blume, can alleviate CP-induced AKI and to explore its underlying mechanisms.

MATERIALS AND METHODS

Experiments were conducted with a CP-induced AKI mouse model and an immortalized human renal tubular epithelial cell line (HK-2). Serum creatinine, Periodic acid-Schiff staining, tissue iron, glutathione, malondialdehyde, and 4-Hydroxynonenal were detected in serum and kidney samples to observe whether GAS inhibits CP-induced tubule ferroptosis. The drug target was verified by detecting the effects of GAS on sirtuin-1 (SIRT1) activity in vitro. Transcriptional regulation of glutathione peroxidase 4 (GPX4) by forkhead box O3A (FOXO3A) was verified by siRNA knockdown, overexpression, and chromatin immunoprecipitation. The effects of FOXO3A, SIRT1, and GAS on CP-induced ferroptosis were measured with propidium iodide, dihydroethidium, monobromobimane, and dipyrromethene boron difluoride staining in HK-2 cells. The relationship between GAS and the SIRT1/FOXO3A/GPX4 pathway was studied using Western blotting.

RESULTS

GAS treatment inhibited CP-induced reactive oxygen species, lipid peroxidation, and tubule death in the cell and animal models. GAS activated SIRT1 in vitro. The SIRT1 inhibitor blocked the protective role of GAS in reducing lipid peroxidation in HK-2 cells. FOXO3A transcriptionally regulated GPX4 expression and inhibited CP-induced cell ferroptosis. Compared to CP-damaged mouse kidneys, GAS-treated mice demonstrated significantly increased SIRT1 and GPX4 expression levels, decreased CP-induced acetylation of FOXO3A, and inhibited lipid peroxidation and cell death.

CONCLUSIONS

GAS alleviated CP-induced AKI by inhibiting ferroptosis via the SIRT1/FOXO3A/GPX4 signaling pathway. The results offer new insights into the development of new anti-AKI drugs from traditional Chinese medicine.

Exposure to anticancer drugs modulates the expression of ACSL4 and ABCG2 proteins in adrenocortical carcinoma cells

Adrenocortical carcinoma (ACC) is a rare and malignant disease, with more than 50 % of patients developing hormone-secreting tumors. These tumors are genetically heterogeneous and potentially lethal, as metastasis is often underway at the time of diagnosis. While chemoresistance can be multifactorial, Acyl CoA synthetase 4 (ACSL4) is known to contribute to the generation of highly aggressive cellular phenotypes, while increased expression and activity of multidrug transporters such as ATP-binding cassette subfamily G member 2 (ABCG2) are known to play a key role. Therefore, the objective of this work was to determine changes in the expression of ACSL4 and ABCG2 in ACC cell lines after exposure to antitumor drugs. Bioinformatics analysis of public database GSE140818 revealed higher ACSL4 and ABCG2 expression in HAC15 cells resistant to mitotane when compared to wild type cells. In addition, our studies revealed an increase in ACSL4 and ABCG2 expression in lowly aggressive H295R cells undergoing early treatment with non-lethal concentrations of mitotane, doxorubicin and cisplatin. Comparable results were obtained in lowly aggressive breast cancer cells MCF-7. The increase in ACSL4 and ABCG2 expression favored tumor cell viability, proliferation and compound efflux, an effect partially offset by ACSL4 and ABCG2 inhibitors. These results provide relevant data on the undesired molecular effects of antitumor drugs and may fuel future studies on patients' early response to antitumor treatment.

Systemic exposure to cisplatin and paclitaxel after intraperitoneal chemotherapy in ovarian cancer

PURPOSE

To determine the systemic exposure to cisplatin and paclitaxel after adjuvant intraperitoneal administration in patients with advanced ovarian cancer who underwent primary debulking surgery. This could provide an explanation for the high incidence of systemic adverse events associated with this treatment regimen.

METHODS

This is a prospective pharmacokinetic study in patients with newly diagnosed advanced ovarian cancer who were treated with intraperitoneal administered cisplatin and paclitaxel. Plasma and peritoneal fluid samples were obtained during the first treatment cycle. The systemic exposure to cisplatin and paclitaxel was determined and compared to previously published exposure data after intravenous administration. An exploratory analysis was performed to investigate the relation between systemic exposure to cisplatin and the occurrence of adverse events.

RESULTS

Pharmacokinetics of ultrafiltered cisplatin were studied in eleven evaluable patients. The geometric mean [range] peak plasma concentration (C_max) and area under the plasma-concentration time curve (AUC_0-24 h) for cisplatin was 2.2 [1.8-2.7] mg/L and 10.1 [9.0-12.6] mg h/L, with a coefficient of variation (CV%) of 14 and 13.0%, respectively. The geometric mean [range] observed plasma concentration of paclitaxel was 0.06 [0.04-0.08] mg/L. No correlation was found between systemic exposure to ultrafiltered cisplatin and adverse events.

CONCLUSION

Systemic exposure to ultrafiltered cisplatin after intraperitoneal administration is high. In addition to a local effect, this provides a pharmacological explanation for high incidence of adverse events seen after intraperitoneal administration of high-dose cisplatin. The study was registered at ClinicalTrials.gov under registration number NCT02861872.

Precise quantitative evaluation of pharmacokinetics of cisplatin using a radio-platinum tracer in tumor-bearing mice

OBJECTIVE

The platinum-based antineoplastic drug cisplatin is commonly used for chemotherapy in clinics. This work aims to demonstrate a radio-platinum tracer is useful for precisely quantifying small amounts of platinum in pharmacokinetics studies.

METHODS

A cisplatin radiotracer (radio-cisplatin) was synthesized, and a comprehensive evaluation of cisplatin over 7 days after its intravenous injection into nude mice bearing a subcutaneous lung tumor (H460) was conducted.

RESULTS

A biphasic retention curve in the whole body and blood was observed [ T1/2 (α) = 1.14 h, T1/2 (β) = 5.33 days for the whole body, and T1/2 (α) = 23.9 min, T1/2 (β) = 4.72 days for blood]. The blood concentration decreased within 1 day after injection. Most of the intact cisplatin was excreted via the kidneys in the early time points, and a small part was distributed in tissues including tumors. The plasma protein binding rate of cisplatin increased rapidly after injection, and the protein-bound cisplatin remained in the blood longer than intact cisplatin. The peak uptake in H460 tumors was 4.7% injected dose per gram at 15 min after injection, and the area under the curve (AUC 0-7 days ) was approximately one-half to one-third of the AUC 0-7 days in the kidneys, liver, and bone, where some toxicity is observed in humans.

CONCLUSION

The radio-platinum tracer revealed the highly quantitative biodistribution of cisplatin, providing insights into the properties of cisplatin, including its adverse effects. The tracer enables a precise evaluation of pharmacokinetics for platinum-based drugs with high sensitivity.

Evaluation of rapid transepithelial electrical resistance (TEER) measurement as a metric of kidney toxicity in a high-throughput microfluidic culture system

Rapid non-invasive kidney-specific readouts are essential to maximizing the potential of microfluidic tissue culture platforms for drug-induced nephrotoxicity screening. Transepithelial electrical resistance (TEER) is a well-established technique, but it has yet to be evaluated as a metric of toxicity in a kidney proximal tubule (PT) model that recapitulates the high permeability of the native tissue and is also suitable for high-throughput screening. We utilized the PREDICT96 high-throughput microfluidic platform, which has rapid TEER measurement capability and multi-flow control, to evaluate the utility of TEER sensing for detecting cisplatin-induced toxicity in a human primary PT model under both mono- and co-culture conditions as well as two levels of fluid shear stress (FSS). Changes in TEER of PT-microvascular co-cultures followed a dose-dependent trend similar to that demonstrated by lactate dehydrogenase (LDH) cytotoxicity assays and were well-correlated with tight junction coverage after cisplatin exposure. Additionally, cisplatin-induced changes in TEER were detectable prior to increases in cell death in co-cultures. PT mono-cultures had a less differentiated phenotype and were not conducive to toxicity monitoring with TEER. The results of this study demonstrate that TEER has potential as a rapid, early, and label-free indicator of toxicity in microfluidic PT-microvascular co-culture models.

Full-dose cisplatin chemotherapy combined with hemodialysis in a patient with impaired renal function and a mediastinal germ cell tumor

Cisplatin is the first choice treatment in mediastinal germ cell tumors. However, concerns regarding increased toxicity of cisplatin hamper its administration in patients with impaired renal function. We describe a 42-year-old man with chronic kidney disease stage 4 who was diagnosed with a mediastinal germ cell tumor and metastases in lung and brain. Treatment with cisplatin-etoposide was considered essential for a chance of cure. In order to administer the full cisplatin dose, 4-hour hemodialysis sessions were performed after each cisplatin infusion. During treatment cycle 3, 4 and 5, total and unbound plasma platinum concentrations were measured. Trough concentrations and half-life were at the higher end of the range of those observed in patients with adequate renal function who received the same dose of cisplatin. Hemodialysis aided platinum clearance, although our patient was also able to clear some platinum by his own renal function. With this full dose treatment, our patient obtained a favorable tumor response, with a strong decrease of beta-human chorionic gonadotropin and tumor size. The side effects experienced by our patient were serious, although not worse than what could be expected with this type of treatment. His renal function remained stable during the treatment period.

Safety and efficacy of administering reduced doses of pegylated recombinant human granulocyte-colony stimulating factors in patients treated with cisplatin and etoposide for small cell carcinoma: A retrospective study

BACKGROUND

The aim of this study was to discuss the safety and efficacy of administering reduced doses (3 mg) of pegylated recombinant human granulocyte-colony stimulating factor (PEG-rhG-CSF) at approximately 24 h or up to three days following treatment with etoposide and cisplatin (EP).

METHODS

A total of 104 cycles from 31 patients were divided into a PEG-rhG-CSF prophylaxis group (PP-Group) and a control group (No-PP-Group). The PP-Group received a reduced dose of 3 mg of PEG-rhG-CSF within a minimum of 15 h and a maximum of 72 h following EP chemotherapy, while the rest did not receive any G-CSF prophylaxis (No-PP-Group). For both groups, complete blood counts, incidence of febrile neutropenia (FN), grade III or IV neutropenia, and the use of antibiotics to treat neutropenia were recorded.

RESULTS

There was statistically no significant difference in the incidence of FN (0% vs. 1.4%, p = 1), antibiotic use due to neutropenia (0% vs. 2.7%, p = 0.881), estimated lowest mean marginal (EM) platelet (106.56 × 10⁹ /L vs. 127.70 × 10⁹ /L, p = 0.056) and hemoglobin (110.48 g/L vs. 110.14 g/L, p = 0.906) levels between the two groups. However, when compared with the No-PP-group, the white blood cell count in the PP-group was significantly higher (EM means: 4.95 × 10⁹ /L vs. 2.80 × 10⁹ /L, p < 0.01), while the incidence of grade III or IV neutropenia was significantly lower (9.1% vs. 68.1%, p < 0.01).

CONCLUSIONS

The administration of a low dose (3 mg) of PEG-rhG-CSF within approximately 24 h or up to three days following EP treatment is safe and effective at reducing the risk of neutropenia. These findings bring a more flexible administration interval between PEG-rhG-CSF and EP treatment.

Diversity of dose-individualization and therapeutic drug monitoring practices of platinum compounds: a review

Introduction: Platinum-derived drugs are commonly used for the treatment of solid tumors. The differences in chemical structures of these molecules lead to different pharmacological properties, in terms of indication, efficacy, and toxicity. Their pharmacokinetics (PK) differ according to their respective renal elimination and have led to many studies investigating their dose optimization. Area covered: This review attempts to summarize and compare PK and pharmacodynamics of cisplatin, carboplatin, and oxaliplatin, with an emphasis on differences of dose calculations and opportunities for therapeutic drug monitoring (TDM) in various patient populations. Expert opinion: Although cisplatin and carboplatin can be considered as analogs since they share the same DNA interacting properties, the slower hydrolysis of the latter results in a better safety profile. Carboplatin is the only drug in oncology to be administrated according to a target area under the curve of concentration versus time, considering that its PK variability is almost fully explained by renal function, not by body size. This enables individual dosing based on predicted carboplatin clearance (along with patients renal characteristics) or on actual clearance with TDM, especially in a high-dose protocol.

The use of Hediste diversicolor in the study of emerging contaminants

The contamination of aquatic environments has been the focus of research to understand effects on ecosystems and its species. Benthic organisms are considered potential targets since sediments act as sources and sinks for environmental contaminants. This review presents information on the effects of three types of emerging contaminants: pharmaceuticals (tested concentrations between 0.1 ng/L - 250 mg/L and 0.01 ng/g - 2.5 μg/g), metal-based nanoparticles (<100 nm) (tested concentrations between 10 μg/L - 1 mg/L and 5 - 140 μg/g) and micro(nano)plastics (tested concentrations between 5 μg/L - 50 mg/L and 10 - 50 mg/kg), on the polychaete Hediste diversicolor, a key species in estuarine/coastal ecosystems. Data shows that these contaminants promote alterations in burrowing activity (lowest concentration inducing effects: 10 ng/L), neurotransmission and damage related parameters (lowest concentration inducing effects: 100 ng/L). The characteristics of this polychaete, such as regenerative capacity, make the use of this species in biomedical studies involving environmental contaminants valuable.

Cisplatin Eligibility Issues and Alternative Regimens in Locoregionally Advanced Head and Neck Cancer: Recommendations for Clinical Practice

Well-designed randomized trials provide the highest level of scientific evidence to guide clinical decision making. In chemoradiotherapy of locally advanced squamous cell carcinoma of the head and neck (SCCHN), data support the use of three cycles of 100 mg/m² cisplatin given every 3 weeks concurrently with conventionally fractionated external beam radiotherapy, although a full compliance with all three cycles is reserved to only about two thirds of initially eligible cases. On an individual patient level, practicing oncologists have to determine whether the patient is a suitable candidate for this treatment or whether contraindications exist. In the latter case, an adequate alternative has to be offered. In this regard, to facilitate triaging of medical information, we reviewed available publications on this topic and prepared practice-oriented recommendations for systemic treatment concurrent to definitive and post-operative radiotherapy. Even if no contraindications for the standard-of-care cisplatin apply, clinicians may opt for alternative regimens by adjusting the peak dose, cumulative dose, or timing of cisplatin. Relative contraindications pose the major issue in clinical practice, as very limited data is available in the literature and final decisions are usually based on an expert opinion or retrospective cohort studies. In the case of absolute interdiction of cisplatin, several alternative regimens incorporating carboplatin, 5-fluorouracil, cetuximab, and docetaxel are available. At the same time, it should be kept in mind that radiotherapy alone represents a viable option with hyperfractionation being particularly beneficial in the definitive management of limited nodal disease. Ideally, all treatment propositions should be discussed within multidisciplinary tumor boards taking into account the patient- and disease-related characteristics as well as local logistics and reimbursement policies.

Low-Dose vs. High-Dose Cisplatin: Lessons Learned From 59 Chemoradiotherapy Trials in Head and Neck Cancer

In locally advanced squamous cell carcinomas of the head and neck (LA-SCCHN), concurrent chemoradiotherapy is an integral part of multimodality management both in the adjuvant and in the definitive settings. Although de-intensification strategies have been propelled to the forefront of clinical research in human papillomavirus (HPV) positive oropharyngeal cancer, three cycles of 100 mg/m² cisplatin given every 3 weeks concurrently with conventionally fractionated external beam radiotherapy represent a cost-effective and globally accessible treatment option for the majority of LA-SCCHN cases. Based on four large randomized trials, this regimen has become the non-surgical standard of care for cisplatin-eligible patients. Nevertheless, the outcomes in terms of efficacy, toxicity, and compliance have been rather disappointing. Therefore, there is an unmet need to find a better alternative. With limited support from randomized trials, weekly low-dose cisplatin regimens have replaced the standard high-dose schedule at some institutions. Four prospective trials exploring radiotherapy with and without weekly low-dose cisplatin have been published. Two of them were conducted in the 1980s, one of which had a negative outcome, the third study provided insufficient information on toxicity, and the fourth trial had to be prematurely terminated due to poor accrual. Moreover, the findings of two phase III trials comparing the two concurrent cisplatin regimens favored the high-dose protocol. We performed a composite meta-analysis of 59 prospective trials enrolling a total of 5,582 patients. The primary endpoint was overall survival. Reflecting different radiotherapy fractionation schemes and treatment intents, three meta-analyses were carried out, one for postoperative conventional chemoradiotherapy, one for definitive conventional chemoradiotherapy, and one for definitive altered fractionation chemoradiotherapy. In the former two settings, both high- and low-dose regimens yielded similar survival outcomes, thus, the primary objective was not met. When given concurrently with altered fractionation radiotherapy, patients treated with high-dose cisplatin had significantly longer overall survival than those who received low-dose cisplatin. In this article we provide a synthetic view of the results, discuss the issue of cumulative dose, compare two vs. three cycles of high-dose cisplatin, and present our three-step recommendations for use of the current standard of care, high-dose cisplatin, in clinical practice.

Weekly Low-Dose Versus Three-Weekly High-Dose Cisplatin for Concurrent Chemoradiation in Locoregionally Advanced Non-Nasopharyngeal Head and Neck Cancer: A Systematic Review and Meta-Analysis of Aggregate Data

BACKGROUND

Three-weekly high-dose cisplatin (100 mg/m²) is considered the standard systemic regimen given concurrently with postoperative or definitive radiotherapy in locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN). However, due to unsatisfactory patient tolerance, various weekly low-dose schedules have been increasingly used in clinical practice. The aim of this meta-analysis was to compare the efficacy, safety, and compliance between these two approaches.

MATERIALS AND METHODS

We systematically searched literature for prospective trials of patients with LA-SCCHN who received postoperative or definitive conventionally fractionated concurrent chemoradiation. Radiation doses were usually 60-66 gray (Gy) in the postoperative setting and 66-70 Gy in the definitive setting. Standard, three-weekly high-dose cisplatin (100 mg/m², 3 doses) was compared with the weekly low-dose protocol (≤50 mg/m², ≥6 doses). The primary endpoint was overall survival. Secondary outcomes comprised response rate, acute and late adverse events, and treatment compliance.

RESULTS

Fifty-two studies with 4,209 patients were included in two separate meta-analyses according to the two clinical settings. There was no difference in treatment efficacy as measured by overall survival or response rate between the chemoradiation settings with low-dose weekly and high-dose three-weekly cisplatin regimens. In the definitive treatment setting, the weekly regimen was more compliant and significantly less toxic with respect to severe (grade 3-4) myelosuppression (leukopenia p = .0083; neutropenia p = .0024), severe nausea and/or vomiting (p < .0001), and severe nephrotoxicity (p = .0099). Although in the postoperative setting the two approaches were more equal in compliance and with clearly less differences in the cisplatin-induced toxicities, the weekly approach induced more grade 3-4 dysphagia (p = .0026) and weight loss (p < .0001).

CONCLUSION

In LA-SCCHN, current evidence is insufficient to demonstrate a meaningful survival difference between the two dosing regimens. Prior to its adoption into routine clinical practice, the low-dose weekly approach needs to be prospectively compared with the standard three-weekly high-dose schedule.

IMPLICATIONS FOR PRACTICE

Given concurrently with conventional radiotherapy in locally advanced head and neck cancer, high-dose three-weekly cisplatin has often been replaced with weekly low-dose infusions to increase compliance and decrease toxicity. The present meta-analysis suggests that both approaches might be equal in efficacy, both in the definitive and postoperative settings, but differ in toxicity. However, some toxicity data can be influenced by unbalanced representation, and the conclusions are not based on adequately sized prospective randomized studies. Therefore, low-dose weekly cisplatin should not be used outside clinical trials but first prospectively studied in adequately sized phase III trials versus the high-dose three-weekly approach.

Ecotoxicological assessment of the anticancer drug cisplatin in the polychaete Nereis diversicolor

Anticancer drugs are designed to inhibit tumor cell proliferation by interacting with DNA and altering cellular growth factors. When released into the waterbodies of municipal and hospital effluents these pharmaceutical compounds may pose a risk to non-target aquatic organisms, due to their mode of action (cytotoxic, genotoxic, mutagenic and teratogenic). The present study aimed to assess the ecotoxicological potential of the alkylating agent cisplatin (CisPt) to the polychaete Nereis diversicolor, at a range of relevant environmental concentrations (i.e. 0.1, 10 and 100ngPtL^-1). Behavioural impairment (burrowing kinetic impairment), ion pump effects (SR Ca²⁺-ATPase), neurotoxicity (AChE activity), oxidative stress (SOD, CAT and GPXs activities), metal exposure (metallothionein-like proteins - MTLP), biotransformation (GST), oxidative damage (LPO) and genotoxicity (DNA damage), were selected as endpoints to evaluate the sublethal responses of the ragworms after 14-days of exposure in a water-sediment system. Significant burrowing impairment occurred in worms exposed to the highest CisPt concentration (100ngPtL^-1) along with neurotoxic effects. The activity of antioxidant enzymes (SOD, CAT) and second phase biotransformation enzyme (GST) was inhibited but such effects were compensated by MTLP induction. Furthermore, LPO levels also increased. Results showed that the mode of action of cisplatin may pose a risk to this aquatic species even at the range of ngL^-1.

[50th anniversary of cisplatin]

We have just celebrated the 50th anniversary of cisplatin cytotoxic potential discovery. It is time to take stock… and it seems mainly positive. This drug, that revolutionized the treatment of many cancer types, continues to be the most widely prescribed chemotherapy. Despite significant toxicities, resistance mechanisms associated with treatment failures, and unresolved questions about its mechanism of action, the use of this cytotoxic agent remains unwavering. The interest concerning this "old" invincible drug has not yet abated. Indeed many research axes are in the news. New platinum salts agents are tested, new cisplatin formulations are developed to target tumor cells more efficiently, and new combinations are established to increase the cytotoxic potency of cisplatin or overcome the resistance mechanisms.

Cisplatin Concentrations in Long and Short Duration Infusion: Implications for the Optimal Time of Radiation Delivery

INTRODUCTION

Cisplatin has radiosensitizing properties and the best sensitization to radiotherapy occurs with a higher plasma concentration of cisplatin. To our knowledge the optimal time sequence between chemotherapy and administration of radiation therapy, to obtain maximum effect from concurrent chemoradiation is unclear.

AIM

The aim of this study was to measure the two cisplatin infusion regimens in order to determine the total and free cisplatin post infusion concentration changes over time. These changes may have clinical implications on the optimum time of administration of post infusion radiation therapy.

MATERIALS AND METHODS

Two cohorts of patients were recruited and both, total and free plasma concentration of cisplatin following long and short durations of intravenous infusion was determined. Blood samples were collected at 0.5, 1, 1.5, 2, 3 and 5 hours from the start of the infusion in the 1hour infusion group and at 2, 3, 3.5, 4, 6 and 24 hours from the start of the infusion, in the 3 hour infusion group. Total and free cisplatin concentrations were measured using a validated HPLC-UV method.

RESULTS

The highest concentration of total and free cisplatin was achieved at the end of the infusion in both regimens. Total cisplatin concentration declined 30 minutes after the end of infusion in both the groups. After 1hour of discontinuing cisplatin, the free cisplatin concentration also declined significantly.

CONCLUSION

We conclude that radiation should be administered within 30 minutes of completion of the infusion irrespective of the duration of infusion.

Biological Monitoring of Exposure to Cisplatin in Rats Using SOS Chromotest

Cisplatin (CDDP) is a potent antitumor drug used in the treatment of a variety of solid tumors. The purpose of the present study was to establish screening biomarker of exposure to CDDP using SOS chromotest. The ultimate goal of this screen is to facilitate the choice of an effective drug and the prognosis of the therapy. In the current screening protocol, the SOS chromotests were performed on the urine of Sprague-Dawley rats administered intravenously with CDDP. Urine samples were collected individually in the metabolic cage at 6 (U0–6) and 12 hours (U6–12) after treatment and were tested their DNA damaging effects. The urine samples obtained from the rats administered with 1 mg/kg CDDP did not induce SOS response in our experimental conditions. At a dose of 5 mg/kg, two out of five rat showed more than 50% increase in the DNA damaging effect compared to that of the control. The genotoxic effect was observed only in the U0–6, whereas the U6–12 were not genotoxic but cytotoxic to the test strain. Similar results were obtained at a dose of 10 mg/kg: 5 out of 10 rats showed SOS response and the U6–12 were also proven to be cytotoxic. These results suggest that the method presented in this study could be used as a biomarker of exposure to CDDP.

Clinical recommendations for defining platinum unsuitable head and neck cancer patient populations on chemoradiotherapy: A literature review

Toxicities resulting from platinum based chemotherapy in head and neck cancer is a cause for much concern. There is a lack of clinical criteria for defining these patient populations, which has posed serious problems associated with increased morbidity and consequently an adverse effect on patients' quality of life. In addition, there is a lack of consensus on clinical criteria for defining such patient populations, who may be unsuitable for concurrent chemoradiotherapy. A group of experts in the field of head and neck cancer from the Asia Pacific Region convened in August 2014 in Korea to discuss the development of a set of clinical criteria in order to fill the knowledge gap and provide a reference tool for head and neck oncologists. This paper reports the final output from this meeting and the accompanying literature review, with the aim of aiding clinical decision making with the help of some clinical criteria to identify platinum unsuitable patient populations in head and neck cancer management. Some alternative treatment options are also discussed in this paper.

Aging increases the susceptibility of cisplatin-induced nephrotoxicity

Cisplatin (CDDP) nephrotoxicity is one of the most common side effects in cancer treatment, causing the disruption of chemotherapy. In this study, we analyzed the influence of nongenetic factors on CDDP-induced nephrotoxiciy using the data from 182 CDDP-treated and 52 carboplatin (CBP)-treated patients. The mean change of eGFR (100% to baseline) in CDDP-treated patients was -9.2%, which was significantly lower than that in the population with CBP therapy. By using the chi-squared test and multivariate logistic regression analysis, age (≥50 years) is found associated with CDDP-induced nephrotoxicity, with odds ratio (OR) of 9.167 and 11.771, respectively. Three- and 18-month-old mice were employed to study the age-dependent susceptibility of CDDP-induced nephrotoxicity. Biochemical parameters, histopathogical examination, and mRNA biomarkers indicated that old mice were subjected to more severe kidney injury. In addition, old mice accumulated more CDDP in kidney than young mice, and the protein level of CDDP efflux transporter, MATE1, in aged mice kidney was 35% of that in young mice. Moreover, inflammatory receptor TLR4 was higher in the kidney of old mice, indicating the alteration of inflammatory signaling in old mice. After CDDP administration, the induced alterations of TNF-α, ICAM-1, and TLR4 were more extensive in old mice. To summarize, aging increased the susceptibility of CDDP-induced renal function decline or nephrotoxicity.

Assessing cisplatin-induced ototoxicity and otoprotection in whole organ culture of the mouse inner ear in simulated microgravity

Cisplatin is a widely used anti-cancer drug. Ototoxicity is a major dose-limiting side-effect. A reproducible mammalian in-vitro model of cisplatin ototoxicity is required to screen and validate otoprotective drug candidates. We utilized a whole organ culture system of the postnatal mouse inner ear in a rotating wall vessel bioreactor under "simulated microgravity" culture conditions. As previously described this system allows whole organ culture of the inner ear and quantitative assessment of ototoxic effects of aminoglycoside induced hair cell loss. Here we demonstrate that this model is also applicable to the assessment of cisplatin induced ototoxicity. In this model cisplatin induced hair cell loss was dose and time dependent. Increasing exposure time of cisplatin led to decreasing EC50 concentrations. Outer hair cells were more susceptible than inner hair cells, and hair cells in the cochlear base were more susceptible than hair cells in the cochlear apex. Initial cisplatin dose determined the final extent of hair cell loss irrespective if the drug was withdrawn or continued. Dose dependant otoprotection was demonstrated by co-administration of the antioxidant agent N-acetyl l-cysteine. The results support the use of this inner ear organ culture system as an in vitro assay and validation platform for inner ear toxicology and the search for otoprotective compounds.

Comparison of cochlear cell death caused by cisplatin, alone and in combination with furosemide

Establishment of appropriate animal models is an important step in exploring the mechanisms of drug-induced ototoxicity. In the present study, using guinea pigs we compared cochlear lesions induced by cisplatin administered in two regimens: consecutive application alone and in combination with furosemide. The effects of furosemide alone were also evaluated; it was found to cause temporary hearing loss and reversible damage to the stria vascularis. Consecutive application of cisplatin alone appeared to be disadvantageous because it resulted in progressive body weight loss and higher mortality compared to the combined regimen, which used a smaller cisplatin dose. The combined regimen resulted in comparable hearing loss and hair cell loss but a markedly lower mortality. However, their coadministration failed to cause similar damage to spiral ganglion neurons (SGN), as seen in animals that received cisplatin alone. This difference suggests that the combined regimen did not mimic the damage to cochlear neuronal innervation caused by the clinical application of cisplatin. The difference also suggests that the SGN lesion is not caused by cisplatin entering the cochlea via the stria vascularis.

Constancy in Integrated Cisplatin Plasma Concentrations Among Pediatric Patients

The authors report on the variability in the integrated quantity of free (unbound) plasma cisplatin (area under curve of plasma concentration versus time, AUC). The AUC was measured in 19 patients receiving cisplatin doses proportional to body surface areas (BSA), 30 mg/m2 over 1 hour. The relative standard deviation (RSD, population standard deviation divided by mean value) for the maximum free plasma cisplatin concentration (Cmax, microM) was 0.338; for the half-life (t1/2, minute), 0.210; and for the AUC (microM minute), 0.320. Thus, BSA-based dosing gave significant variability in the AUC. We attempted to use (weight)a(height)b, seeking values of a and b that gave the smallest RSD in AUC, but only minimal improvement could be obtained by deviating from the BSA formula (a=b=0.5). However, dosing proportional to (weight)d(Cmax)f (with d approximately 3/4 and f approximately -1) reduced the RSD in AUC from approximately 1/3 to approximately 1/10. Dosing proportional to (weight)m (Cmax)n(t1/2)p (with m approximately 0.7, n approximately -1, and p approximately -1/2) reduced it further, to approximately 1/32. In contrast, using (weight)d(Cmax)f(age)g gave no improvement over (weight)d(Cmax)f. The authors conclude that the inconsistency in AUC can be reduced 10-fold with dosing proportional to the weight and the drug pharmacokinetic parameters [(weight0.7)/(Cmaxxt1/2(0.5))].

Relationship between hematotoxicity and serum albumin level in the treatment of head and neck cancers with concurrent chemoradiotherapy using cisplatin

OBJECTIVE

Patients with locally advanced head and neck cancer were treated with concurrent chemoradiotherapy using three courses of cisplatin. However, many patients were unable to complete the scheduled cisplatin treatment due to adverse effects. The objective of this study was to retrospectively elucidate the source of the low completion rate of cisplatin courses.

METHODS

Between November 2007 and 28 May 2010, patients with head and neck cancer were treated with curative intent according to the concurrent chemoradiotherapy protocol (66-70 Gy at 2 Gy/day with cisplatin 80 mg/m(2) on Days 1, 22 and 43). Treatment courses, hematological data and other parameters were investigated, and the treatment completion rates and reasons for treatment failure were analyzed.

RESULTS

Among the 28 patients, cisplatin was administered during the period of radiotherapy a total of 3 times in 9 (32%) patients, 2 times in 15 (54%) patients and only 1 time in 4 (14%) patients. Multiple regression analysis of the development of neutropenia at 3 weeks after the first cisplatin administration revealed that the serum albumin level was a significant explanatory variable (R(2)= 0.664, β = 0.517, P< 0.01). Pearson's product-moment correlation coefficient showed a strong correlation between the serum albumin level and the neutrophil count after 3 weeks (r = 0.605, P< 0.01).

CONCLUSIONS

The treatment completion rate by this protocol was low in head and neck cancer patients even when the cisplatin dose was reduced to 80 mg/m(2). This tendency was seen in patients with a low serum albumin level.

A phase I/II trial of pixantrone (BBR2778), methylprednisolone, cisplatin, and cytosine arabinoside (PSHAP) in relapsed/refractory aggressive non-Hodgkin's lymphoma

The purpose of the study was to evaluate the safety, efficacy, and pharmacokinetics of pixantrone (BBR2778) when substituted for etoposide in the ESHAP regimen in patients with aggressive relapsed or refractory non-Hodgkin's lymphoma. Nineteen patients received protocol therapy, consisting of pixantrone 80 mg/m2 over 1 h on day 1, methylprednisolone 500 mg on days 1 - 5, cisplatin 25 mg/m2 on days 1 - 4, and cytarabine 2000 mg/m2 on day 5. Cycles were repeated every 21 days, in the outpatient setting. Dose limiting toxicity, consisting of bone marrow suppression, occurred at the first dose level (80 mg/m2), which was defined as the recommended dose. Grade 3 and 4 toxicities were mainly hematologic. Only one patient had grade 4 febrile neutropenia. No significant decreases in ejection fraction greater than 20% occurred. Overall response rate was 58%, with 37% complete and 21% partial responses. Six of the 11 responders (55%) underwent stem cell transplant. Median time to progression and overall median survival were 5.7 months and 14.5 months, respectively. There is no significant interaction between pixantrone and the combined drugs. The recommended dose of pixantrone in combination with methylprednisolone, cytarabine, and cisplatin (PSHAP) is 80 mg/m2. PSHAP is an active salvage regimen and should be further evaluated as a pretransplant cytoreductive regimen.

Pharmacokinetic evaluation of platinum derived from cisplatin administered alone and with pemetrexed in head and neck cancer patients

PURPOSE

This phase I study characterized the pharmacokinetics of free and total platinum derived from cisplatin administered alone and in combination with pemetrexed. Secondary objectives were to assess the pharmacokinetics of pemetrexed when it is combined with cisplatin as well as to evaluate the safety profile and document antitumor activity associated with this combination.

METHODS

An open-label, two-arm, cross-over phase 1 study was performed in patients with squamous cell carcinoma of the head and neck, age > or =18 years, an Eastern Cooperative Oncology Group performance status of 0-2, and adequate organ function. Blood samples were taken and pharmacokinetics evaluated for the first two cycles using noncompartmental analysis. Patients received either pemetrexed (500 mg m(-2)) plus cisplatin (75 mg m(-2)) administered in cycle 1 followed by cisplatin alone in cycle 2; or in the reverse order (i.e., cisplatin alone in cycle 1 followed by pemetrexed plus cisplatin in cycle 2). Each treatment cycle was 21 days and patients received folic acid, vitamin B(12) supplementation, and dexamethasone prophylaxis. After the first two cycles, patients continued study treatment with pemetrexed plus cisplatin every 3 weeks up to a maximum of six total treatment cycles. Toxicities were graded by the investigators according to the National Cancer Institute Common Toxicity Criteria for Adverse Events (CTCAE), version 3.0.

RESULTS

A total of 13 patients were treated; one patient was discontinued from the study after cycle 1 for failure to meet baseline eligibility criteria for renal function. The ratios and 90% confidence intervals (CI) comparing the pharmacokinetics for cisplatin administered with pemetrexed to those for cisplatin administered alone for free platinum were: C(max) = 1.08 (CI: 0.92, 1.27) and AUC = 0.93 (CI: 0.82, 1.06); and, total platinum were: C(max) = 0.97 (CI: 0.88, 1.06) and AUC = 0.87 (CI: 0.81, 0.93). These results indicate that platinum pharmacokinetics (free and total) are similar, whether cisplatin is administered alone or combined with pemetrexed. The pemetrexed pharmacokinetic results were consistent with those from previous single-agent pemetrexed studies and a previous study of pemetrexed in combination with cisplatin. The combination of pemetrexed and cisplatin did not show any unexpected toxicities. Consistent with the platinum pharmacokinetic results, co-administration with pemetrexed did not appear to enhance cisplatin-related toxicities. Of the 13 treated patients, 11 had stable disease as the best overall response and 2 had progressive disease.

CONCLUSIONS

The pharmacokinetics of free platinum derived from cisplatin were not altered by co-administration with pemetrexed, and in agreement with this, no unexpected cisplatin-induced toxicities were observed when these drugs were combined.

Human Red Blood Cells: Rheological Aspects, Uptake, and Release of Cytotoxic Drugs

The shape of a normal human red blood cell (RBC) is well known: under resting conditions it is that of a biconcave discocyte. However, RBCs can easily undergo transformation to other shapes with stomatocytes and echinocytes as extremes. Various anticancer agents, generally reactive and labile substances, e.g., oxazaphosphorines and fluoropyrimidines, can induce severe deformation of shape. Shape changes in erythrocytes can induce rheological disturbances, which occasionally have pathophysiological consequences. It is difficult to estimate the impact of shape changes on the in vivo behavior of agents of biological interest. However, it has been demonstrated for various anticancer agents that erythrocytes fulfill an important role in their uptake, transport, and release. Moreover, some anticancer agents are capable of influencing important transporters such as MRP and GLUT-1. Monitoring of erythrocyte concentrations of certain cytotoxic agents is therefore of interest as the data generated can have a predictive outcome for therapeutic efficacy. This is true for cyclophosphamide, ifosfamide, lometrexol, and 6-mercaptopurine, as well as MRP and GLUT-1 mediated agents.

Population pharmacokinetics of total and unbound plasma cisplatin in adult patients

AIMS

To investigate the pharmacokinetics of unbound (ultrafilterable) and total plasma platinum using a population approach and to identify patient characteristics that may influence the disposition of the drug.

METHODS

Pharmacokinetic and demographic data were collected from adult patients treated with 30-min daily infusions of cisplatin for various malignancies. Unbound and total platinum concentration-time data were analysed using a nonlinear mixed effects model.

RESULTS

Data from 43 patients were available for analysis. A linear two-compartment model best described total and unbound platinum plasma concentration-time data. The mean population estimates for total and unbound drug were, respectively, 0.68 and 35.5 l h(-1) for clearance and 21.1 and 23.4 l for central distribution volume (V(1)). Unbound clearance (CL) was dependent on body surface area (BSA) and creatinine clearance, and V(1) was dependent on BSA. The elimination rate constant for plasma-bound platinum (modelled as metabolite formation) was 0.014 h(-1). The pharmacokinetic parameter, f(m)/V(m), a measure of the clearance of unbound platinum due to irreversible plasma binding, was related to serum protein concentration and to the inverse of dose per m(2). The covariate modelling of CL, V(1) and f(m)/V(m) improved the intersubject variabilities associated with these parameters. The final pharmacokinetic models were validated using 200 bootstrap samples from the original datasets.

CONCLUSIONS

The results support the conventional dose adjustment of cisplatin based on BSA. They also support the need for a dose reduction in case of renal insufficiency.

Current research in avian chemotherapy

Chemotherapy as a treatment modality is increasingly being used in avian oncology. Currently, most chemotherapeutic agents can only be used empirically, as pharmacokinetic data in birds are lacking.Recently, the pharmacokinetic profile of the platinum analogs,cisplatin, and carboplatin has been reported in Sulfur-crested cockatoos,paving the way for clinical and toxicity trials.

Pharmacokinetics of platinum after oral or intravenous cisplatin: a phase 1 study in 32 adult patients

AIMS

To develop a population pharmacokinetic model for simultaneous analysis of oral/intravenous cisplatin data in order to estimate the mean population pharmacokinetic parameters, mainly the bioavailability, of cisplatin and to evaluate the influence of covariates on the pharmacokinetic variability.

METHODS

Pharmacokinetic and demographic data were collected from 32 adult patients (20 males/12 females, age range 47-76 years) receiving 30-min infusions or an oral formulation of cisplatin, 10-30 mg/m2, for various malignancies. Both total plasma and ultrafilterable or unbound platinum concentrations were determined.

RESULTS

Unbound and total platinum concentrations were ascribed to a two-compartment model, with first-order absorption and elimination. The oral bioavailability (F) population estimates were, respectively, 0.39 and 0.30 with associated intersubject variabilities (ISV) of 24% and 26%. Peak concentrations following oral dosing occurred at 1.0 h and 1.6 h for unbound and total platinum, respectively. Clearance (CL) and central distribution volume (V1) of unbound platinum were significantly related to body surface area (BSA). The CL and V1 mean estimates were, respectively, 37 l/h and 23 l with an associated ISV of 15%. The final pharmacokinetic models were validated using 1000 bootstrap samples of the original datasets.

CONCLUSIONS

Both unbound and total platinum data allowed a fair evaluation of oral cisplatin disposition, with close estimations for both absorption rates and oral bioavailability. These results also support the conventional dose adjustment of cisplatin based on BSA.

Population pharmacokinetics of cisplatin after 120-h infusion: application to routine adaptive control with feedback

OBJECTIVE

A Bayesian population pharmacokinetics study of data from routine therapeutic drug monitoring cisplatin during a 5-day infusion of cisplatin.

METHODS

A total of 95 kinetics data sets (58 patients) were available to perform this study. Individual pharmacokinetic parameters, estimated from 20 courses of treatment in 18 patients, were used to calculate the population parameters (cl: 0.175 +/- 0.034 L/h; t(1/2): 327 +/- 91 h). The accuracy of Bayesian forecasting was tested by comparing in 40 other patients the clearance values calculated either from a complete kinetics profile (eight sampling times) or from three early samples and the new population parameters. Finally, drug monitoring efficacy was assessed by comparing the target Cmax values with the Cmax obtained after dose adjustment based upon early Bayesian estimation of the individual pharmacokinetic parameters.

RESULTS

: No significant difference was found between Bayesian and experimental clearances. Besides, dose-individualization proved to successfully adjust Cmax values around their respective target.

CONCLUSION

The new reference pharmacokinetic population parameters lead to accurate estimation of individual pharmacokinetic parameters from a limited number of samples, thus allowing efficient therapeutic drug monitoring during 5-day infusion regimens of cisplatin.

Retinoids enhance cisplatin-based chemoradiation in cervical cancer cells in vitro

OBJECTIVE

The aim of this study was to determine whether receptor-dependent and receptor-independent retinoids sensitize cervical cancer cells to clinically relevant doses of concurrent radiation and cisplatin.

METHODS

The clonogenic assay was performed on SiHa cervical carcinoma cultures treated with 5 microM 9-cis-retinoic acid (RA) or 3 microM 4-HPR for 3 days prior to and following concurrent treatment with 3 microM cisplatin and 2 Gy of Co(60) radiation.

RESULTS

Neither 9-cis-RA nor 4-HPR significantly decreased survival for radiation only or cisplatin only (t test: P < 0.05), but both significantly decreased survival of cultures receiving concurrent chemoradiation (t test: 9-cis-RA P = 0.045; 4-HPR P = 0.027).

CONCLUSIONS

Both receptor-dependent and receptor-independent retinoids enhance concurrent chemoradiation effects in vitro.

Simple and rapid determination of carboplatin in plasma by high-performance liquid chromatography. Error pattern and application to clinical pharmacokinetic studies

Carboplatin is an antitumor agent widely employed in cancer chemotherapy. A specific and selective method for the determination of carboplatin in human plasma and its applications to pharmacokinetic investigations is described. One ultrafiltration step, through a Centrifree micropartition system (Amicon) at 2000 g for 10 min, is the only requirement as sample treatment. The resulting solution is injected into an Inertsil ODS-2 (5 microm, 25 cm x 4.6 mm I.D.) analytical column. The mobile phase consisted of 0.1 M potassium dihydrogenphosphate with 1 mM dipotassium edetate adjusted to a pH between 3 and 3.5. The limit of quantitation was 1 mg/l. The method showed good recovery (100.68+/-5.49%) and precision: the within-day relative standard deviation (RSD) for carboplatin (3-350 mg/l) was 2.07% and the between-day RSD for carboplatin, in the previously described range, was 1.31%. We determined the assay error pattern for proper weighting of serum level data in pharmacokinetic models. The selectivity (discrimination between the parent drug and platinum-containing species such as carboplatin metabolites), simplicity and speed of this assay for free carboplatin quantitation should facilitate pharmacokinetic investigations and therapeutic drug monitoring.

Drug therapy for gynaecological cancer in older women

A substantial proportion of all women dying from gynaecological malignancies are aged >75 years. Many reports have indicated that the survival of these patients is decreased compared with younger patients. Differences in biological behaviour, stage of the disease at presentation, and reluctance to undergo aggressive treatment with its associated morbidity are among the factors thought to be responsible for this difference in outcomes. However, investigations also indicate that elderly patients may receive less surgical and chemotherapeutic treatment without obvious clinical rationale. This overview is aimed at providing a guideline of chemotherapy appropriate for patients with epithelial ovarian, uterine (corpus and cervix), and vulvar cancer, aged 70 to 75 years and over. Platinum-based chemotherapy is the cornerstone of drug treatment in patients with ovarian cancer. Patients aged between 70 and 75 years with a good performance status can be treated with cisplatin- or carboplatin-based chemotherapy. Carboplatin, either in combination or as a single-agent, may offer advantages in patients aged >75 years and in those with a poor performance status. For patients with early recurrence there is no standard treatment, but several cytostatic and hormonal agents can be used with palliative intent. Patients with a late recurrence are probably best retreated with a platinum-based regimen. In metastatic endometrial cancer, hormonal therapy is the first choice in tumours expressing a progesterone receptor. Poorly differentiated tumours infrequently respond to endocrine therapy. In this situation, and for patients with tumours that have become resistant to hormonal manipulation, platinum-based chemotherapy may be used. The use of carboplatin-based regimens seems preferable in elderly patients, particularly in those with a decreased performance status. The usefulness of chemotherapy in elderly patients with cervical cancer is limited. In case of recurrent or metastatic disease, the use of single agent (low-dose) cisplatin should be balanced against best supportive care. Although overall chemoradiation seems superior than radiotherapy alone in patients with locally advanced cervical cancer, the feasibility of this approach in elderly patients needs further investigation. Chemoradiation might also be considered in patients with locally advanced vulvar cancer. However, treatment-related morbidity can be considerable and randomised studies are lacking to prove a survival benefit. Our understanding of the tolerance and effectiveness of chemotherapy in elderly patients is still incomplete due to a paucity of trials that specifically focus on this subset of patients. However, there appears no argument to withhold chemotherapy based purely on age.

Platinum pharmacokinetics in sulphur-crested cockatoos (Cacatua galerita) following single-dose cisplatin infusion

OBJECTIVE

To determine the pharmacokinetics of platinum (Pt) in cockatoos.

DESIGN

A pharmacokinetic study of Pt, following a single i.v. infusion of cisplatin, was done in six healthy sulphur-crested cockatoos (Cacatua galerita).

PROCEDURE

Birds were hydrated for 1 h before and 2 h after a 1-h cisplatin infusion (1 mg/kg, i.v.). Serial blood samples were collected for 96 h after initiation of the infusion and urine was collected for 2 h during the hydration period after cisplatin administration. Tissue samples from 10 organs were obtained at necropsy, 96 h after cisplatin infusion. Total Pt and filterable Pt in plasma, urinary Pt and tissue Pt concentrations were assayed by inductively coupled plasma-mass spectrometry. A noncompartmental pharmacokinetic analysis was performed on the plasma and urine data.

RESULTS

For total Pt and filterable Pt, the respective mean systemic clearances were 0.373 and 0.699 L/kg hourly, the steady state volumes of distribution were 4.19 and 0.356 L/kg, and the mean residence times were 111 and 0.512 h. Total plasma Pt displayed a bi-exponential decay profile with average half-lives of 0.398 and 79.0 h, while filterable Pt had a monoexponential decay with mean half-life of 0.413 h. The renal clearance during the 2-h postinfusion period was 0.167 L/kg hourly. The kidneys had the highest Pt accumulation (4.54 micrograms/g DM).

CONCLUSIONS AND CLINICAL RELEVANCE

Cisplatin infusion in cockatoos was well tolerated and Pt plasma concentrations were similar to those measured during treatment of solid tumours in human patients. Despite anatomical, physiological and biochemical differences among animal species, the pharmacokinetic disposition of Pt in the cockatoo shares some features with the kinetics reported previously in rodents, dogs and human beings.

Oxaliplatin: pharmacokinetics and chronopharmacological aspects

Oxaliplatin is the first clinically available diaminocyclohexane platinum coordination complex. The drug is non-cross-resistant with cisplatin or carboplatin and is one of the few active drugs against human colorectal cancer. Its cytotoxicity is synergistic with fluorouracil and folinic acid (leucovorin), the reference treatment for this disease. The main cumulative dose-limiting toxicity of oxaliplatin is peripheral sensory neuropathy. The drug can also produce diarrhoea, vomiting and haematological suppression. Unlike cisplatin, no renal failure or peripheral motor neuropathy have been reported and the sensory neuropathy is partly reversible. Unlike carboplatin, oxaliplatin produces only mild to moderate haematological toxicity. Oxaliplatin undergoes biotransformation into aquated forms in the blood, where 3 species can be found: total platinum, ultrafilterable or 'free' platinum and erythrocyte platinum. Flameless atomic absorption (FAAS) is used for assaying platinum concentration in various tissues. Inductively-coupled plasma mass spectrometry (ICP-MS), with a >10-fold lower sensitivity threshold than FAAS, was also used for the determination of oxaliplatin pharmacokinetics. The pharmacokinetics of oxaliplatin are described by a 3-compartment model. The drug rapidly crosses the cellular membrane as a result of its lipophilicity. Hence, at the end of a 2-hour infusion, approximately 40% of the blood platinum is found in erythrocytes. The distribution half-life of ultrafiltrated plasma platinum ranges from 10 to 25 minutes and its terminal elimination half-life is 26 hours (determined with FAAS) or 270 hours (ICP-MS). The elimination half-life of erythrocytic platinum is 12 to 50 days, close to that of erythrocytes. 30 to 50% of the platinum is recovered in the urine within 2 to 5 days, with renal clearance accounting for half of the total clearance of ultrafiltrated platinum. The total clearance of this species is correlated with the glomerular filtration rate. No pharmacokinetic-pharmacodynamic relationship has been established for oxaliplatin. Pharmacokinetic alterations produced by fluorouracil + folinic acid or irinotecan were minimal if any. The prolonged stability of oxaliplatin makes it suitable for continuous infusions over 4 to 5 days, with a delivery rate which can be either constant or chronomodulated (peak rate at 1600h), using programmable ambulatory pumps. Chronomodulation significantly reduces toxicity and improves antitumour activity as compared with constant rate infusion. These differences in pharmacodynamic properties were paralleled by differences in plasma concentration time courses. The different drug concentration profiles achieved with different infusional modalities may be useful tools for understanding the relationship between the pharmacokinetics and pharmacodynamics of oxaliplatin and may lead to further optimisation of its administration schedule and its combination with other drugs.

Determination of platinum complexes in clinical samples by a rapid flameless atomic absorption spectrometry assay

The frequent use of platinum (Pt) complexes in cancer chemotherapy and the application of new therapeutic options and dosing strategies have increased the need for rapid analytic procedures to determine Pt concentrations in the biologic fluids of patients. Therefore a flameless atomic absorption spectrometry method for the quantification of Pt in plasma and ultrafiltrate was developed and validated. A simple sample preparation of only one dilution step was established. Only 400 microL of whole blood was required for duplicate analysis of Pt in both matrices. The matrix-specific temperature programs took less than 75 seconds. The lower limit of quantification was 40 ng Pt/mL and 20 ng Pt/mL for plasma and ultrafiltrate, respectively. Suitable linearity could be reached using separate calibration curves for the high and low Pt concentration ranges. Recovery of Pt was complete, and there were no major stability problems. The accuracy and precision of the new method met the international criteria for the validation of bioanalytic methods. In addition, the use of different anticoagulants for clinical sampling, ultrafiltration systems, and ultrafiltration conditions were investigated. The assay has already been extensively applied to pharmacokinetic studies. In conclusion, the new Pt assay proved to be rapid, simple, sensitive, and suitable for clinical use.

Absorbed doses to patients from 191Pt-, 193mPt- and 195mPt-cisplatin

Cisplatin, a chemotherapeutic drug, can be synthesized using radioactive platinum and then used for pharmacokinetic studies and tumor imaging. We have calculated the absorbed doses to various organs and tissues as well as the effective doses from 191Pt-, 193mPt- and 195mPt-cisplatin after administration to humans for diagnostic purposes. Liver was the organ that received the highest absorbed dose. The effective dose from 191Pt-, 193mPt- and 195mPt-cisplatin was 0.10 +/- 0.02, 0.17 +/- 0.04 and 0.23 +/- 0.05 mSv/MBq respectively.

Radiotherapy and concurrent continuous infusion of cisplatin with adjuvant surgery in nonresectable Stage III lung carcinoma: short- and long-term results of a Phase II study

PURPOSE

Cisplatin-enhanced radiotherapy plus adjuvant surgery was evaluated in nonresectable non-small cell lung carcinoma (NSCLC).

METHODS AND MATERIALS

Doses of 50 Gy (administered in standard fractionation in 5 weeks) were delivered with concurrent cisplatin in continuous infusion (daily dose: 4 mg/m2), to 32 Stage IIIa and 45 Stage IIIb patients enrolled in a Phase II study. Patients without progression underwent surgery.

RESULTS

Esophagitis (64%), nausea/vomiting (34%), and pulmonary toxicity (14%) were the main side effects. Grade 3 toxicity occurred in 4 instances. A clinical locoregional major response was achieved by 55 patients (there were 10 complete responses). Forty patients underwent surgery, 7 with a nonradical procedure. Seven patients died due to surgery-related complications, which were significantly impacted by right pneumonectomy (71% vs. 6% of the other procedures, p < 0.0001). Eighteen of the 40 surgical patients were assessed to be without viable tumor and 11 with microresidual carcinoma. There were 13 disease-free, 5-year survivors.

CONCLUSIONS

Toxicity was low but activity high with the chemoradiotherapy. Adjuvant surgery increased the rate of complete responses, but right pneumonectomy had an unacceptable mortality. The role of surgery needs further refinement. Integration of the chemoradiotherapy schedule with cisplatin-based induction chemotherapy is advisable.

Mechanisms of synergism between cisplatin and gemcitabine in ovarian and non-small-cell lung cancer cell lines

2',2'-Difluorodeoxycytidine (gemcitabine, dFdC) and cis-diammine-dichloroplatinum (cisplatin, CDDP) are active agents against ovarian cancer and non-small-cell lung cancer (NSCLC). CDDP acts by formation of platinum (Pt)-DNA adducts; dFdC by dFdCTP incorporation into DNA, subsequently leading to inhibition of exonuclease and DNA repair. Previously, synergism between both compounds was found in several human and murine cancer cell lines when cells were treated with these drugs in a constant ratio. In the present study we used different combinations of both drugs (one drug at its IC25 and the other in a concentration range) in the human ovarian cancer cell line A2780, its CDDP-resistant variant ADDP, its dFdC-resistant variant AG6000 and two NSCLC cell lines, H322 (human) and Lewis lung (LL) (murine). Cells were exposed for 4, 24 and 72 h with a total culture time of 96 h, and possible synergism was evaluated by median drug effect analysis by calculating a combination index (CI; CI < 1 indicates synergism). With CDDP at its IC25, the average CIs calculated at the IC50, IC75 IC90 and IC95 after 4, 24 and 72 h of exposure were < 1 for all cell lines, indicating synergism, except for the CI after 4 h exposure in the LL cell line which showed an additive effect. With dFdC at its IC25, the CIs for the combination with CDDP after 24 h were < 1 in all cell lines, except for the CIs after 4 h exposure in the LL and H322 cell lines which showed an additive effect. At 72 h exposure all CIs were < 1. CDDP did not significantly affect dFdCTP accumulation in all cell lines. CDDP increased dFdC incorporation into both DNA and RNA of the A2780 cell lines 33- and 79-fold (P < 0.01) respectively, and tended to increase the dFdC incorporation into RNA in all cell lines. In the AG6000 and LL cell lines, CDDP and dFdC induced > 25% more DNA strand breaks (DSB) than each drug alone; however, in the other cell lines no effect, or even a decrease in DSB, was observed. dFdC increased the cellular Pt accumulation after 24 h incubation only in the ADDP cell line. However, dFdC did enhance the Pt-DNA adduct formation in the A2780, AG6000, ADDP and LL cell lines (1.6-, 1.4-, 2.9- and 1.6-fold respectively). This increase in Pt-DNA adduct formation seems to be related to the incorporation of dFdC into DNA (r = 0.91). No increase in DNA platination was found in the H322 cell line. dFdC only increased Pt-DNA adduct retention in the A2780 and LL cell lines, but decreased the Pt-DNA adduct retention in the AG6000 cell line. In conclusion, the synergism between dFdC and CDDP appears to be mainly due to an increase in Pt-DNA adduct formation possibly related to changes in DNA due to dFdC incorporation into DNA.

Gamma camera imaging of platinum in tumours and tissues of patients after administration of 191Pt-cisplatin

The aim of this study was to visualize non-invasively the uptake of platinum in tumours and tissues after treatment with cisplatin. 191Pt-cisplatin was synthesized from 191PtCl4 with rigorous pharmaceutical quality control. The uptake of platinum by both tumorous and healthy tissues was studied by gamma camera imaging in 14 patients, 5 of whom showed a clear uptake of platinum in regions corresponding to known tumour sites. Maximum concentrations of platinum in the tumours were on average 4.9+/-1.0 microg/g, when normalized to an administered amount of 180 mg cisplatin. In all the patients, the liver was the organ that showed the highest uptake. Platinum uptake was also seen in the spleen, gall bladder, gastrointestinal tract, bladder, kidneys, ureter, neck and mediastinum and urogenital region. By using in-house production of 191Pt-cisplatin, it was possible to monitor the uptake of platinum in tumorous tissues and healthy organs.