Clinical pharmacokinetics of carboplatin

Exogenous Metabolic Modulators Improve Response to Carboplatin in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) lacks targeted therapies, leaving cytotoxic chemotherapy as the current standard treatment. However, chemotherapy resistance remains a major clinical challenge. Increased insulin-like growth factor 1 signaling can potently blunt chemotherapy response, and lysosomal processes including the nutrient scavenging pathway autophagy can enable cancer cells to evade chemotherapy-mediated cell death. Thus, we tested whether inhibition of insulin receptor/insulin-like growth factor 1 receptor with the drug BMS-754807 and/or lysosomal disruption with hydroxychloroquine (HCQ) could sensitize TNBC cells to the chemotherapy drug carboplatin. Using in vitro studies in multiple TNBC cell lines, in concert with in vivo studies employing a murine syngeneic orthotopic transplant model of TNBC, we show that BMS-754807 and HCQ each sensitized TNBC cells and tumors to carboplatin and reveal that exogenous metabolic modulators may work synergistically with carboplatin as indicated by Bliss analysis. Additionally, we demonstrate the lack of overt in vivo toxicity with our combination regimens and, therefore, propose that metabolic targeting of TNBC may be a safe and effective strategy to increase sensitivity to chemotherapy. Thus, we conclude that the use of exogenous metabolic modulators, such as BMS-754807 or HCQ, in combination with chemotherapy warrants additional study as a strategy to improve therapeutic responses in women with TNBC.

A Novel MDM2-Binding Chalcone Induces Apoptosis of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) represents ~90% of all oral cancers, being the eighth most common cancer in men. The overall 5-year survival rate is only 39% for metastatic cancers, and currently used chemotherapeutics can cause important side effects. Thus, there is an urgency in developing new and effective anti-cancer agents. As both chalcones and 1,2,3-triazoles are valuable pharmacophores/privileged structures in the search for anticancer compounds, in this work, new 1,2,3-triazole-chalcone hybrids were synthesized and evaluated against oral squamous cell carcinoma. By using different in silico, in vitro, and in vivo approaches, we demonstrated that compound 1f has great cytotoxicity and selectivity against OSCC (higher than carboplatin and doxorubicin) and other cancer cells in addition to showing minimal toxicity in mice. Furthermore, we demonstrate that induced cell death occurs by apoptosis and cell cycle arrest at the G2/M phase. Moreover, we found that 1f has a potential affinity for MDM2 protein, similar to the known ligand nutlin-3, and presents a better selectivity, pharmacological profile, and potential to be orally absorbed and is not a substrate of Pg-P when compared to nutlin-3. Therefore, we conclude that 1f is a good lead for a new chemotherapeutic drug against OSCC and possibly other types of cancers.

Pharmacokinetics of Carboplatin in Combination with Low-Dose Cyclophosphamide in Female Dogs with Mammary Carcinoma

This prospective study aimed to evaluate the effect of metronomic cyclophosphamide on carboplatin’s tolerability, efficacy, and pharmacokinetics in dogs with mammary carcinoma. Sixteen female dogs with mammary carcinoma were divided into groups: 300 mg/m2 intravenous (i.v.) carboplatin therapy (G1 = 8) or 300 mg/m2 i.v. carboplatin which was associated with 12.5 mg/m2 oral cyclophosphamide in a metronomic regimen (G2 = 8). The investigated animals underwent a clinical evaluation, a mastectomy, a carboplatin chemotherapy, and serial blood sampling for the pharmacokinetic analysis. The adverse events and survival rates were monitored. A non-compartmental analysis was applied to calculate the pharmacokinetic parameters of carboplatin in the 2nd and 4th chemotherapy cycles. Carboplatin PK showed high interindividual variability with a 10-fold variation in the area under the plasma concentration−time curve (AUC) in G1. The systemic plasma exposure to carboplatin was equivalent in both of the treatments considering the AUC and maximum plasma concentration (Cmax) values. Although the red blood cells (p < 0.0001), platelets (p = 0.0005), total leukocytes (p = 0.0002), and segmented neutrophils (p = 0.0007) were reduced in G2, the survival rate increased (p = 0.0044) when it was compared to G1. In conclusion, adding low daily doses of cyclophosphamide to a carboplatin therapy showed promising outcomes in female dogs with mammary tumors.

Pro-Apoptotic Antitumoral Effect of Novel Acridine-Core Naphthoquinone Compounds against Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is a global public health problem with high incidence and mortality. The chemotherapeutic agents used in the clinic, alone or in combination, usually lead to important side effects. Thus, the discovery and development of new antineoplastic drugs are essential to improve disease prognosis and reduce toxicity. In the present study, acridine-core naphthoquinone compounds were synthesized and evaluated for their antitumor activity in OSCC cells. The mechanism of action, pharmacokinetics, and toxicity parameters of the most promising compound was further analyzed using in silico, in vitro, and in vivo methods. Among the derivatives, compound 4e was highly cytotoxic (29.99 µM) and selective (SI 2.9) at levels comparable and generally superior to chemotherapeutic controls. Besides, compound 4e proved to be non-hemolytic, stable, and well tolerated in animals at all doses tested. Mechanistically, compound 4e promoted cell death by apoptosis in the OSCC cell, and molecular docking studies suggested this compound possibly targets enzymes important for tumor progression, such as RSK2, PKM2, and topoisomerase IIα. Importantly, compound 4e presented a pharmacological profile within desirable parameters for drug development, showing promise for future preclinical trials.

Carboplatin dose calculations for patients with lung cancer: significant dose differences found depending on dosing equation choice

Background

Carboplatin is the backbone cytotoxic agent for many chemotherapy regimens for lung cancer. Dosing of carboplatin is complicated due to its relationship to renal function and narrow therapeutic index. Overestimation of renal function may lead to supratherapeutic dosing and toxicity, while underestimation may lead to underdosing and therapeutic failure. Although the Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations have higher accuracy in estimating glomerular filtration rate (eGFR), the Cockcroft Gault (CG) formula has been historically used for carboplatin dosing internationally.

Methods

We compared these formulae to identify patient profiles that were associated with significant carboplatin dose variation by retrospectively analysing the carboplatin dosing of 96 patients with lung cancer. Carboplatin doses were calculated using eGFR generated by MDRD, CKD-EPI ²⁰⁰⁹ and CKD-EPI ²⁰²¹ equations. These three hypothetical doses were compared to actual CG-based doses prescribed.

Results

MDRD and CKD-EPI equations resulted in comparable carboplatin doses; however, CG doses diverged markedly with up to 17% of the patients receiving a carboplatin dose that was at least 20% higher than a non-CG formula would have predicted, and 20% received a dose that was at least 20% lower than a non-CG formula would have predicted. Our data suggest CG use overestimates kidney function in patients with a higher bodyweight and body surface area (BSA) while underestimating it in patients with a lower bodyweight and BSA. Importantly, we demonstrate potential real-world benefit as CKD-EPI predicted lower doses for patients whose (CG-derived) carboplatin dose was later reduced following clinical assessment prior to infusion.

Conclusions

We have therefore confirmed significant differences in carboplatin dosing depending on the equation used in our modern patient population and suggest that use of CKD-EPI provides the most clinically appropriate carboplatin dosing and should be implemented as the new standard of care internationally.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09885-7.

Enhancing Circulation and Tumor Accumulation of Carboplatin via an Erythrocyte-Anchored Prodrug Strategy

The short circulatory half-lives and low tumor accumulation of carboplatin greatly limit the drug's efficacy in vivo. Herein, we address these challenges by using a prodrug strategy and present the rational design of a novel platinum(IV) anticancer prodrug that can hitchhike on erythrocytes. This prodrug, designated as ERY1-Pt^IV , can bind to erythrocytes efficiently and stably, possessing a circulatory half-life 18.5 times longer than that of carboplatin in mice. This elongated circulatory half-life enables platinum to accumulate at levels 7.7 times higher than with carboplatin, with steady levels in the tumors. As a consequence, the ERY1-Pt^IV prodrug is proved to exhibit significantly enhanced antitumor activity and reduced side effects compared with carboplatin. Collectively, our novel approach highlights an efficient strategy to utilize intrinsic erythrocytes as auto-binding carriers to enhance the tumor accumulation and subsequent antitumor efficacy of platinum drugs.

Quantitative magnetic resonance imaging and tumor forecasting of breast cancer patients in the community setting

This protocol describes a complete data acquisition, analysis and computational forecasting pipeline for employing quantitative MRI data to predict the response of locally advanced breast cancer to neoadjuvant therapy in a community-based care setting. The methodology has previously been successfully applied to a heterogeneous patient population. The protocol details how to acquire the necessary images followed by registration, segmentation, quantitative perfusion and diffusion analysis, model calibration, and prediction. The data collection portion of the protocol requires ~25 min of scanning, postprocessing requires 2-3 h, and the model calibration and prediction components require ~10 h per patient depending on tumor size. The response of individual breast cancer patients to neoadjuvant therapy is forecast by application of a biophysical, reaction-diffusion mathematical model to these data. Successful application of the protocol results in coregistered MRI data from at least two scan visits that quantifies an individual tumor's size, cellularity and vascular properties. This enables a spatially resolved prediction of how a particular patient's tumor will respond to therapy. Expertise in image acquisition and analysis, as well as the numerical solution of partial differential equations, is required to carry out this protocol.

Validation of a multicellular tumor microenvironment system for modeling patient tumor biology and drug response

Lung cancer rates are rising globally and non-small cell lung cancer (NSCLC) has a five year survival rate of only 24%. Unfortunately, the development of drugs to treat cancer is severely hampered by the inefficiency of translating pre-clinical studies into clinical benefit. Thus, we sought to apply a tumor microenvironment system (TMES) to NSCLC. Using microvascular endothelial cells, lung cancer derived fibroblasts, and NSCLC tumor cells in the presence of in vivo tumor-derived hemodynamic flow and transport, we demonstrate that the TMES generates an in-vivo like biological state and predicts drug response to EGFR inhibitors. Transcriptomic and proteomic profiling indicate that the TMES recapitulates the in vivo and patient molecular biological state providing a mechanistic rationale for the predictive nature of the TMES. This work further validates the TMES for modeling patient tumor biology and drug response indicating utility of the TMES as a predictive tool for drug discovery and development and potential for use as a system for patient avatars.

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.

Phase I study of metformin in combination with carboplatin/paclitaxel chemotherapy in patients with advanced epithelial ovarian cancer

Background Metformin use is associated with reduced cancer risk in epidemiological studies and has preclinical anti-cancer activity in ovarian cancer models. The primary objective of this phase I study was to determine the recommended phase II dose (RP2D) of metformin in combination with carboplatin/paclitaxel in patients with ovarian cancer. Secondary objectives were to describe safety and pharmacokinetics. Methods In this single-center trial the RP2D of metformin in combination with carboplatin area under the concentration-time curve (AUC) 6 and paclitaxel 175 mg/m2 every 3 weeks (q3w) in patients with advanced epithelial ovarian cancer was determined using a 3 + 3 escalation rule at three fixed dose levels: 500 mg three times daily (tds), 850 mg tds and 1000 mg tds. Metformin was commenced on day 3 of cycle 1 and continued until 3 weeks after the last chemotherapy administration. The RP2D was defined as the dose level at which 0 of 3 or ≤ 1 of 6 evaluable subjects experienced a metformin-related dose-limiting toxicity (DLT). Safety was assessed according to CTCAE v4.0. Plasma and serum samples for pharmacokinetic (PK) analyses were collected during treatment cycles 1 and 2. Results Fifteen patients with epithelial ovarian cancer and an indication for neo-adjuvant (n = 5) or palliative (n = 10) treatment were included. No DLTs were observed. Three patients discontinued study treatment during cycle 1 for other reasons than DLT. Six patients were treated at the RP2D of metformin 1000 mg tds. The most frequent low-grade toxicities were anemia, hypomagnesemia and diarrhea. Grade 3 adverse events (AEs) occurred in ten patients, most common were leucopenia (n = 4), thrombocytopenia (n = 3) and increased GGT (n = 3). There were no grade 4 AEs. Metformin increased the platinum (Pt) AUC (Δ22%, p = 0.013) and decreased the Pt clearance (Δ-28%, p = 0.013). Metformin plasma levels were all within the therapeutic range for diabetic patients (0.1-4 mg/L). Conclusion The RP2D of metformin in combination with carboplatin and paclitaxel in advanced ovarian cancer is 1000 mg tds. This is higher than the RP2D reported for combination with targeted agents. A potential PK interaction of metformin with carboplatin was identified.

Clinical Pharmacokinetics and Pharmacodynamics of Transarterial Chemoembolization and Targeted Therapies in Hepatocellular Carcinoma

The management of hepatocellular carcinoma (HCC) is based on a multidisciplinary decision tree. Treatment includes loco-regional therapy, mainly transarterial chemoembolization, for intermediate-stage HCC and systemic therapy with oral tyrosine kinase inhibitors (TKIs) for advanced HCC. Transarterial chemoembolization involves hepatic intra-arterial infusion with either conventional procedure or drug-eluting-beads. The aim of the loco-regional procedure is to deliver treatment as close as possible to the tumor both to embolize the tumor area and to enhance efficacy and minimize systemic toxicity of the anticancer drug. Pharmacokinetic studies applied to transarterial chemoembolization are rare and pharmacodynamic studies even rarer. However, all available studies lead to the same conclusions: use of the transarterial route lowers systemic exposure to the cytotoxic drug and leads to much higher tumor drug concentrations than does a similar dose via the intravenous route. However, reproducibility of the procedure remains a major problem, and no consensus exists regarding the choice of anticancer drug and its dosage. Systemic therapy with TKIs is based on sorafenib and lenvatinib as first-line treatment and regorafenib and cabozantinib as second-line treatment. Clinical use of TKIs is challenging because of their complex pharmacokinetics, with high liver metabolism yielding both active metabolites and their common toxicities. Changes in liver function over time with the progression of HCC adds further complexity to the use of TKIs. The challenges posed by TKIs and the HCC disease process means monitoring of TKIs is required to improve clinical management. To date, only partial data supporting sorafenib monitoring is available. Results from further pharmacokinetic/pharmacodynamic studies of these four TKIs are eagerly awaited and are expected to permit such monitoring and the development of consensus guidelines.

Short-term organoid culture for drug sensitivity testing of high-grade serous carcinoma

OBJECTIVE

Cancer patient-derived organoids (PDOs) grow as three dimensional (3D) structures in the presence of extracellular matrix and have been found to represent the original tumor's genetic complexity. In addition, PDOs can be grown and subjected to drug sensitivity testing in a shorter time course and with lesser expense than patient-derived xenograft models. Many patients with recurrent ovarian cancer develop malignant effusions that become refractory to chemotherapy. Since these same patients often present for palliative aspiration of ascites or pleural effusions, there is a potential opportunity to obtain tumor specimens in the form of multicellular spheroids (MCS) present in malignant effusion fluids. Our objective was to develop a short duration culture of MCS from ovarian cancer malignant effusions in conditions selected to support organoid growth and use them as a platform for empirical drug sensitivity testing.

METHODS

In this study, malignant effusion specimens were collected from patients with high-grade serous ovarian carcinoma (HGSOC). MCS were recovered and subjected to culture conditions designed to support organoid growth. In a subset of specimens, RNA-sequencing was performed at two time points during the short-term culture to determine changes in transcriptome in response to culture conditions. Organoid induction was also characterized in these specimens using Ki67 staining and histologic analysis. Drug sensitivity testing was performed on all specimens.

RESULTS

Our model describes organoids formed within days of primary culture, which can recapitulate the histological features of malignant ascites fluid and can be expanded for at least 6 days. RNA-seq analysis of four patient specimens showed that within 6 days of culture, there was significant up-regulation of genes related to cellular proliferation, epithelial-mesenchymal transition, and KRAS signaling pathways. Drug sensitivity testing identified several agents with therapeutic potential.

CONCLUSIONS

Short duration organoid culture of MCS from HGSOC malignant effusions can be used as a platform for empiric drug sensitivity testing. These ex vivo models may be helpful in screening new or existing therapeutic agents prior to individualized treatment options.

New insights on cytostatic drug risk assessment in aquatic environments based on measured concentrations in surface waters

Cytostatic drugs are compounds used to treat cancer, one of the deadliest diseases worldwide with a rising yearly incidence. However, the occurrence and concentrations of a large number of cytostatics in waters and wastewaters are unknown. Thus, this study sought to analyze the concentrations of these compounds in different aquatic environments worldwide to assess the risk that these compounds pose to aquatic organisms. The top five most monitored cytostatics in aquatic environments are fluorouracil, methotrexate, tamoxifen, ifosfamide, and cyclophosphamide. Risk quotients (RQs) based on maximum reported measured concentrations revealed that mycophenolic acid and tamoxifen pose a high risk to aquatic organisms (RQ_max ≥ 1) at concentrations observed in surface waters. Moreover, methotrexate and tegafur were categorized as moderate risk compounds, and bicalutamide was found to pose a low risk. Importantly, the available analytical methodologies for the quantification of some cytostatics (e.g., cisplatin, fluorouracil, daunorubicin, imatinib, and mycophenolic acid) in water could not rule out potential risk to aquatic biota, since estimated risks for these compounds using the lowest method detection limits reported in the literature (RQ MDL) were all ≥0.01 (i.e., low risk or higher). Moreover, risks based on predicted concentrations (RQ PEC) were consistently lower than those based on measured concentrations, highlighting the importance of risk assessment based on measured values. Thus, accurate and sensitive analytical methods are crucial to identify and quantify cytostatic exposure in aquatic ecosystems in order to preserve biodiversity and ensure a safer environment.

Inhibition of activin signaling in lung adenocarcinoma increases the therapeutic index of platinum chemotherapy

Resistance to platinum chemotherapy is a long-standing problem in the management of lung adenocarcinoma. Using a whole-genome synthetic lethal RNA interference screen, we identified activin signaling as a critical mediator of innate platinum resistance. The transforming growth factor-β (TGFβ) superfamily ligands activin A and growth differentiation factor 11 (GDF11) mediated resistance via their cognate receptors through TGFβ-activated kinase 1 (TAK1), rather than through the SMAD family of transcription factors. Inhibition of activin receptor signaling or blockade of activin A and GDF11 by the endogenous protein follistatin overcame this resistance. Consistent with the role of activin signaling in acute renal injury, both therapeutic interventions attenuated acute cisplatin-induced nephrotoxicity, its major dose-limiting side effect. This cancer-specific enhancement of platinum-induced cell death has the potential to dramatically improve the safety and efficacy of chemotherapy in lung cancer patients.

Live Cell Mass Accumulation Measurement Non-Invasively Predicts Carboplatin Sensitivity in Triple-Negative Breast Cancer Patient-Derived Xenografts

Prompt and repeated assessments of tumor sensitivity to available therapeutics could reduce patient morbidity and mortality by quickly identifying therapeutic resistance and optimizing treatment regimens. Analysis of changes in cancer cell biomass has shown promise in assessing drug sensitivity and fulfilling these requirements. However, a major limitation of previous studies in solid tumors, which comprise 90% of cancers, is the use of cancer cell lines rather than freshly isolated tumor material. As a result, existing biomass protocols are not obviously extensible to real patient tumors owing to potential artifacts that would be generated by the removal of cells from their microenvironment and the deleterious effects of excision and purification. In this present work, we show that simple excision of human triple-negative breast cancer (TNBC) tumors growing in immunodeficient mouse, patient-derived xenograft (PDX) models, followed by enzymatic disaggregation into single cell suspension, is enabling for rapid and accurate biomass accumulation-based predictions of in vivo sensitivity to the chemotherapeutic drug carboplatin. We successfully correlate in vitro biomass results with in vivo treatment results in three TNBC PDX models that have differential sensitivity to this drug. With a maximum turnaround time of 40 h from tumor excision to useable results and a fully-automated analysis pipeline, the assay described here has significant potential for translation to clinical practice.

Pharmacokinetics and toxicity of subcutaneous administration of carboplatin in poloxamer 407 in a rodent model pilot study

The objectives of this study were to assess the pharmacokinetics and safety of subcutaneously delivered carboplatin in poloxamer 407 in rats. Carboplatin (5mg/rat) in 0.5ml poloxamer 407 (1.0 ml total volume) was administered subcutaneously in a right subcutaneous perineal incision in all 12 treatment rats. Three control rats received 1.0 ml of poloxamer 407. Total platinum was measured in plasma q24hrs from 0 to 168hrs. Protein-unbound platinum was measured in plasma at 168hrs. After sacrifice on day 7, total platinum was determined in wound bed muscle. Platinum concentrations in all samples were measured by ICP-MS. Wounds were visually assessed daily for 7 days. Perineal tissues (full wound bed including muscle, subcutis, skin) were assessed histologically and scored. Total platinum was detectable in plasma from 24 to 168 hrs. Total plasma platinum AUC and C_max were 9,165.3 ng/mL•h and 129.4 ng/mL. Day 7 total platinum concentration in muscle was approximately 10-fold higher than total plasma platinum concentration. No unbound platinum was detected in plasma samples at 168 hours. No wound healing complications were detected at any time point, nor was tissue necrosis observed histologically. The results of this study suggest that subcutaneous carboplatin in poloxamer 407 can be used in vivo providing direct tissue exposure to carboplatin without significant local effects or systemic absorption and without wound healing complications.

Population pharmacokinetic analyses of the effect of carboplatin pretreatment on olaparib in recurrent or refractory women's cancers

PURPOSE

Combining olaparib with carboplatin was recently shown to be active in both BRCA and non-BRCA mutant cancers in a recent phase I/Ib combination trial. The optimal drug sequence recommended was carboplatin 1-day before olaparib. However, carboplatin pre-treatment induced a ~50% faster olaparib clearance.

METHODS

To further explore this drug interaction, a population pharmacokinetic (PK) model was designed that included a lag time parameter, a second absorption compartment from tablet formulation, a single distribution/elimination compartment, and covariance among the clearance and volume parameters.

RESULTS

Clearance (6.8 L/h) and volume (33 L) estimates were comparable with literature. The only significant covariate was the presence of carboplatin on olaparib clearance, consistent with published noncompartmental PK and in vitro data.

CONCLUSIONS

Simulations predicted lower steady-state peak/trough olaparib exposure through 24-36 h post carboplatin pre-treatment, but this effect was lost by day 2 and thus no dose adjustment is recommended.

A pharmacokinetic-pharmacodynamic study on carboplatin administered in prolonged continuous infusion regimens with synchronous radiotherapy

A clinical and pharmacokinetic study was conducted on an outpatient basis in which carboplatin was administered by continuous infusion (20, 25, or 30 mg/d X 5 days X 4 weeks) with synchronous radio therapy. Responses were obtained in 8 of 15 patients, and dose-limiting toxicity was not reached. Leukope nia (grade 1 or 2) occurred in 8 patients, nausea (grade 1 or 2) in 2 patients, and no other toxicity was evident. AUC (area under plasma concentration X time curve) and elimination half-life (1.68 to 2.97 hours) data were similar to values obtained for the rapid intravenous (IV) infusion of carboplatin at an equivalent dose in previous studies. Values of volume of distribution at steady-state (Vdss) were higher following continuous infusion administration as com pared with rapid IV infusion. This was consistent with results from other studies and may possibly be ex plained by altered drug distribution and disposition following continuous infusion therapy. Data were fitted to a mono-exponential elimination curve that was also in agreement with previous reports on carboplatin pharmacokinetics. Relationships between pharmacokinetic variables and pharmacodynamic variables (haematological toxicity) were investigated in order to explore the possibility of developing pharmacokinetically guided dosage schemes for car boplatin given by continuous infusion in a combined modality treatment. A linear correlation (r = 0.71) was evident between the percentage decrease in platelets (at the nadir 4 weeks after the start of infusion) and AUC X normalised radiation field area. Wtih further studies, it is possible that a formula could be derived from this relationship for dose individual isation in patients receiving carboplatin by continu ous infusion with synchronous radiotherapy.

Carboplatin and taxol resistance develops more rapidly in functional BRCA1 compared to dysfunctional BRCA1 ovarian cancer cells

A major risk factor for ovarian cancer is germline mutations of BRCA1/2. It has been found that (80%) of cellular models with acquired platinum or taxane resistance display an inverse resistance relationship, that is collateral sensitivity to the other agent. We used a clinically relevant comparative selection strategy to develop novel chemoresistant cell lines which aim to investigate the mechanisms of resistance that arise from different exposures of carboplatin and taxol on cells having BRCA1 function (UPN251) or dysfunction (OVCAR8). Resistance to carboplatin and taxol developed quicker and more stably in UPN251 (BRCA1-wildtype) compared to OVCAR8 (BRCA1-methylated). Alternating carboplatin and taxol treatment delayed but did not prevent resistance development when compared to single-agent administration. Interestingly, the sequence of drug exposure influenced the resistance mechanism produced. UPN251-6CALT (carboplatin first) and UPN251-6TALT (taxol first) have different profiles of cross resistance. UPN251-6CALT displays significant resistance to CuSO4 (2.3-fold, p=0.004) while UPN251-6TALT shows significant sensitivity to oxaliplatin (0.6-fold, p=0.01). P-glycoprotein is the main mechanism of taxol resistance found in the UPN251 taxane-resistant sublines. UPN251 cells increase cellular glutathione levels (3.0-fold, p=0.02) in response to carboplatin treatment. However, increased glutathione is not maintained in the carboplatin-resistant sublines. UPN251-7C and UPN251-6CALT are low-level resistant to CuSO4 suggesting alterations in copper metabolism. However, none of the UPN251 sublines have alterations in the protein expression of ATP7A or CTR1. The protein expression of BRCA1 and MRP2 is unchanged in the UPN251 sublines. The UPN251 sublines remain sensitive to parp inhibitors veliparib and CEP8983 suggesting that these agents are candidates for the treatment of platinum/taxane resistant ovarian cancer patients.

Methylseleninic acid sensitizes Notch3-activated OVCA429 ovarian cancer cells to carboplatin

Ovarian cancer, the deadliest of gynecologic cancers, is usually not diagnosed until advanced stages. Although carboplatin has been popular for treating ovarian cancer for decades, patients eventually develop resistance to this platinum-containing drug. Expression of neurogenic locus notch homolog 3 (Notch3) is associated with chemoresistance and poor overall survival in ovarian cancer patients. Overexpression of NICD3 (the constitutively active form of Notch3) in OVCA429 ovarian cancer cells (OVCA429/NICD3) renders them resistance to carboplatin treatment compared to OVCA429/pCEG cells expressing an empty vector. We have previously shown that methylseleninic acid (MSeA) induces oxidative stress and activates ataxia-telangiectasia mutated and DNA-dependent protein kinase in cancer cells. Here we tested the hypothesis that MSeA and carboplatin exerted a synthetic lethal effect on OVCA429/NICD3 cells. Co-treatment with MSeA synergistically sensitized OVCA429/NICD3 but not OVCA429/pCEG cells to the killing by carboplatin. This synergism was associated with a cell cycle exit at the G2/M phase and the induction of NICD3 target gene HES1. Treatment of N-acetyl cysteine or inhibitors of the above two kinases did not directly impact on the synergism in OVCA429/NICD3 cells. Taken together, these results suggest that the efficacy of carboplatin in the treatment of high grade ovarian carcinoma can be enhanced by a combinational therapy with MSeA.

Phase I clinical and pharmacokinetic study of ombrabulin (AVE8062) combined with cisplatin/docetaxel or carboplatin/paclitaxel in patients with advanced solid tumors

PURPOSE

Preclinical evidence supports synergy between the vascular disrupting agent ombrabulin and various chemotherapy agents. Ombrabulin was combined with two standard taxane/platinum doublets in a phase I study to determine the recommended combination doses.

METHODS

Ombrabulin (30-min infusion, day 1 every 3 weeks) was escalated from 15.5 to 35 mg/m(2) with two chemotherapy doublets; OCD, 75 mg/m(2) cisplatin (C), day 1 (cohort 1) or day 2 (cohort 2) with 60/75 mg/m(2) docetaxel (D), day 2; and OCP, AUC5/6 carboplatin (C) and paclitaxel (P) 175 mg/m(2) (cohort 3) or 200 mg/m(2) (cohort 4), day 2. Safety, pharmacokinetics, and tumor response were evaluated.

RESULTS

Sixty-nine patients were treated (32 OCD, 37 OCP). Four had DLTs in cycle 1, two in cohort 1 (grade 4 febrile neutropenia, grade 4 pulmonary embolism) and one each in cohorts 2 (grade 3 ALT elevation) and 4 (grade 3 peripheral ischemia). Ombrabulin escalation in cohorts 2, 3 and 4 was halted at the highest planned dose (35 mg/m(2)). Asthenia, nausea, paresthesia, alopecia, vomiting, and stomatitis were common, as was grade 3-4 neutropenia. Ombrabulin clearance was high with a short terminal half-life and a medium volume of distribution. Pharmacokinetic analysis showed no clinically relevant drug interactions between the taxane-platinum doublet and ombrabulin or its active metabolite RPR258063, however docetaxel and carboplatin pharmacokinetics were slightly altered. One complete and 15 partial responses (10 OCD, 5 OCP; median duration 5.5 and 4.4 months, respectively) were reported.

CONCLUSIONS

The addition of ombrabulin to standard doses of cisplatin/docetaxel or carboplatin/paclitaxel proved feasible with manageable overlapping toxicities but appears to have limited impact on the efficacy of these doublets. Recommended combination doses are 35 mg/m(2) ombrabulin with 75 mg/m(2) cisplatin/75 mg/m(2) docetaxel or 200 mg/m(2) paclitaxel/AUC6 carboplatin, every 3 weeks.

Regulation of aggregation behavior and neurotoxicity of prion neuropeptides by platinum complexes

Prion diseases belong to a group of infectious, fatal neurodegenerative disorders. The conformational conversion of a cellular prion protein (PrP(C)) into an abnormal misfolded isoform (PrP(Sc)) is the key event in prion disease pathology. PrP106-126 resembles PrP(Sc) in some physicochemical and biological characteristics, such as apoptosis induction in neurons, fibrillar formation, and mediation of the conversion of native cellular PrP(C) to PrP(Sc). Numerous studies have been conducted to explore the inhibiting methods on the aggregation and neurotoxicity of prion neuropeptide PrP106-126. We showed that PrP106-126 aggregation, as assessed by fluorescence assay and atomic force microscopy, is inhibited by platinum complexes cisplatin, carboplatin, and Pt(bpy)Cl2. ESI-MS and NMR assessments of PrP106-126 and its mutant peptides demonstrate that platinum complexes bind to the peptides in coordination and nonbonded interactions, which rely on the ligand properties and the peptide sequence. In peptides, methionine residue is preferred as a potent binding site over histidine residue for the studied platinum complexes, implying a typical thiophile characteristic of platinum. The neurotoxicity induced by PrP106-126 is better inhibited by Pt(bpy)Cl2 and cisplatin. Furthermore, the ligand configuration contributes to both the binding affinity and the inhibition of peptide aggregation. The pursuit of novel platinum candidates that selectively target prion neuropeptide is noteworthy for medicinal inorganic chemistry and chemical biology.

In vitro Development of Chemotherapy and Targeted Therapy Drug-Resistant Cancer Cell Lines: A Practical Guide with Case Studies

The development of a drug-resistant cell line can take from 3 to 18 months. However, little is published on the methodology of this development process. This article will discuss key decisions to be made prior to starting resistant cell line development; the choice of parent cell line, dose of selecting agent, treatment interval, and optimizing the dose of drug for the parent cell line. Clinically relevant drug-resistant cell lines are developed by mimicking the conditions cancer patients experience during chemotherapy and cell lines display between two- and eight-fold resistance compared to their parental cell line. Doses of drug administered are low, and a pulsed treatment strategy is often used where the cells recover in drug-free media. High-level laboratory models are developed with the aim of understanding potential mechanisms of resistance to chemotherapy agents. Doses of drug are higher and escalated over time. It is common to have difficulty developing stable clinically relevant drug-resistant cell lines. A comparative selection strategy of multiple cell lines or multiple chemotherapeutic agents mitigates this risk and gives insight into which agents or type of cell line develops resistance easily. Successful selection strategies from our research are presented. Pulsed-selection produced platinum or taxane-resistant large cell lung cancer (H1299 and H460) and temozolomide-resistant melanoma (Malme-3M and HT144) cell lines. Continuous selection produced a lapatinib-resistant breast cancer cell line (HCC1954). Techniques for maintaining drug-resistant cell lines are outlined including; maintaining cells with chemotherapy, pulse treating with chemotherapy, or returning to master drug-resistant stocks. The heterogeneity of drug-resistant models produced from the same parent cell line with the same chemotherapy agent is explored with reference to P-glycoprotein. Heterogeneity in drug-resistant cell lines reflects the heterogeneity that can occur in clinical drug resistance.

Antitumor activity of lobaplatin alone or in combination with antitubulin agents in non-small-cell lung cancer

OBJECTIVE

Lobaplatin is used to treat patients with breast cancer, small-cell lung cancer, and chronic myelogenous leukemia in China. In this study, we assessed the in-vitro and in-vivo activities of lobaplatin alone or in combination with antitubulin agents against human non-small-cell lung cancer (NSCLC).

METHODS

The cytotoxicities of lobaplatin against NSCLC cells were determined by the sulforhodamine B (SRB) assay. Cell cycle analysis and apoptosis were assessed using flow cytometry, and the in-vivo antitumor activities were evaluated in human NSCLC xenografts in nude mice.

RESULTS

The cytotoxicity of lobaplatin was similar to or higher than that of cisplatin and carboplatin, with a mean IC(50) of 2.5 μmol/l in a variety of NSCLC cells. In addition, lobaplatin arrested cells in the S phase and triggered apoptosis. The combination of lobaplatin with antitubulin agents yielded synergistic cytotoxic activity in vitro. In NSCLC xenografts, lobaplatin alone showed significant antitumor activity. The combination of lobaplatin with antitubulin agents, especially with paclitaxel, led to significantly enhanced activity, which was superior to that of cisplatin combined with antitubulin agents.

CONCLUSION

These data demonstrate that the use of lobaplatin alone or in combination with antitubulin agents might be a rational and novel therapeutic strategy for human NSCLC and warrants further clinical investigation.

A phase I trial and in vitro studies combining ABT-751 with carboplatin in previously treated non-small cell lung cancer patients

BACKGROUND

ABT-751 is a novel antimitotic agent that exerted cytotoxic effects in preclinical studies. Carboplatin has efficacy in treating advanced non-small cell lung cancer (NSCLC) in combination with other drugs.

METHODS

Lung cancer cell lines were treated with ABT-751 and/or carboplatin to investigate their impact on cell growth. A phase I study with an expansion cohort was conducted in previously treated NSCLC patients. The primary objective was the maximum tolerated dose (MTD); secondary objectives were objective response rates, median survival, time to tumor progression, dose-limiting toxicities (DLTs), and pharmacodynamic evaluation of buccal swabs.

RESULTS

Combining ABT-751 with carboplatin significantly reduced growth and induced apoptosis of lung cancer cell lines. Twenty advanced NSCLC patients were enrolled. MTD was ABT-751 125 mg orally twice daily for 7 days with carboplatin AUC 6. DLTs included fatigue, ileus, neutropenia and pneumonitis. Two patients had confirmed partial responses. Median overall survival was 11.7 months (95% CI 5.9-27.0). Time to tumor progression was 2.8 months (95% CI 2.0-2.7). Four of 6 patients showed decreased cyclin D1 protein in posttreatment versus pretreatment buccal swabs.

CONCLUSION

Combining ABT-751 with carboplatin suppressed growth of lung cancer cell lines and had modest clinical antitumor activity in advanced NSCLC previously treated predominantly with carboplatin. Further studies of this combination are not recommended while investigations of biomarkers in different patient populations, alternative schedules and combinations may be pursued.

Neutrophil dynamics after chemotherapy and G-CSF: the role of pharmacokinetics in shaping the response

Chemotherapy has profound effects on the hematopoietic system, most notably leading to neutropenia. Granulocyte colony stimulating factor (G-CSF) is often used to deal with this neutropenia, but the response is highly variable. In this paper we examine the role of pharmacokinetics and delivery protocols in shaping the neutrophil responses to chemotherapy and G-CSF. Neutrophil responses to different protocols of chemotherapy administration with varying dosages, infusion times, and schedules are studied through a mathematical model. We find that a single dose of chemotherapy produces a damped oscillation in neutrophil levels, and short-term applications of chemotherapy can induce permanent oscillations in neutrophil level if there is a bistability in the system. In addition, we confirm previous findings [Zhuge et al., J. Theor. Biol., 293(2012), 111-120] that when periodic chemotherapy is given, there is a significant period of delivery that induces resonance in the system and exacerbates the corresponding neutropenia. The width of this resonant period peak increases with the recovery rate after a single chemotherapy, which is given by the real part of the dominant eigenvalue pair at the steady state, and both are determined by a single cooperativity coefficient in the feedback function for the neutrophils. Our numerical studies show that the neutropenia caused by chemotherapy can be overcome if G-CSF is given early after chemotherapy but can actually be worsened if G-CSF is given later, consistent with results reported in Zhuge et al. (2012). The nadir in neutrophil level is found to be more sensitive to the dosage of chemotherapy than that of the G-CSF. Furthermore, dependence of our results with changes in key pharmacokinetic parameters as well as initial functions are studied. Thus, this study illuminates the potential for destructive resonance leading to neutropenia in response to periodic chemotherapy, and explores and explains why the timing of G-CSF is so crucial for successful reversal of chemotherapy induced neutropenia.

Genome-wide meta-analysis identifies variants associated with platinating agent susceptibility across populations

Platinating agents are used in the treatment of many cancers, yet they can induce toxicities and resistance that limit their utility. Using previously published and additional world population panels of diverse ancestry totaling 608 lymphoblastoid cell lines (LCLs), we performed meta-analyses of over 3 million SNPs for both carboplatin- and cisplatin-induced cytotoxicity. The most significant SNP in the carboplatin meta-analysis is located in an intron of NBAS (p = 5.1 × 10⁻⁷). The most significant SNP in the cisplatin meta-analysis is upstream of KRT16P2 (p = 5.8 × 10⁻⁷). We also show that cisplatin-susceptibility SNPs are enriched for carboplatin-susceptibility SNPs. Most of the variants that associate with platinum-induced cytotoxicity are polymorphic across multiple world populations; therefore, they could be tested in follow-up studies in diverse clinical populations. Seven genes previously implicated in platinating agent response, including BCL2, GSTM1, GSTT1, ERCC2, and ERCC6 were also implicated in our meta-analyses.

In vitro cytotoxicity of novel platinum-based drugs and dichloroacetate against lung carcinoid cell lines

INTRODUCTION

Chemotherapy for advanced well-differentiated carcinoids is characterised by low response rates and short duration of responses. The present study aimed to assess the in vitro activity of novel platinum-based chemotherapeutic drugs in combination with dichloroacetate (DCA), a sensitiser to apoptosis, against lung carcinoid cell lines.

METHODS

Three permanent cell lines (UMC-11, H727 and H835) were exposed to 14 different established cytotoxic drugs and the novel platinum-based compounds as satraplatin, JM118 and picoplatin in combination with DCA, and viability of the cells was measured using a tetrazoliumbased dye assay.

RESULTS

With exception of the highly chemoresistant UMC- 11 line, the carcinoid cell lines (H727, H835) were sensitive to the majority of chemotherapeutics in vitro. Among the platinum-based drugs, carboplatin and oxaliplatin showed highest efficacy. H835 cells growing as multicellular spheroids were 2.7-8.7-fold more resistant to picoplatin, satraplatin and its metabolite compared to single cell suspensions. DCA (10 mM) inhibited the growth of UMC- 11 cells by 22% and sensitised these highly resistant cells to carboplatin, satraplatin and JM118 1.4-2.4-fold.

CONCLUSION

The highly resistant UMC-11 lung carcinoid cells are sensitive to carboplatin, oxaliplatin and the satraplatin metabolite JM118, but multicellular spheroidal growth, as observed in the H835 cell line and pulmonary tumourlets, seems to increase chemoresistance markedly. The activity of carboplatin and JM118 is significantly and specifically increased in combination with the apoptosis sensitiser DCA that promotes mitochondrial respiration over aerobic glycolysis. In summary, among the novel platinum drugs satraplatin has the potential for treatment of lung carcinoids and DCA potentiates the cytotoxicity of selected platinum drugs.

Population pharmacokinetics of high-dose carboplatin in children and adults

INTRODUCTION

Although for conventional dosing of carboplatin, several strategies are available to individualize the dose based on renal function measurements, such approaches are still rare for high-dose regimens with autologous stem cell support. The purpose of this study was to investigate the influence of patient- and regimen-specific factors on the pharmacokinetics of carboplatin and to compare the performance of different dose individualization strategies (Calvert, Newell, Chatelut, flat dosing, dosing according to body surface area).

PATIENTS AND METHODS

A combined data set with 69 patients from five studies, including 13 pediatric patients, was subject to a population pharmacokinetic analysis using NONMEM.

RESULTS

The covariate analysis revealed that carboplatin clearance after high-dose chemotherapy was highly related to creatinine clearance, body height, and infusion duration. After inclusion of these covariates, the population parameter variability of clearance decreased from 53% in the base model to 21% in the final model. We also developed an alternative model that related body weight, instead of height, to clearance by means of allometric scaling. An evaluation of the predictive performance of existing a priori dose individualization strategies revealed that flat dosing is appropriate for adult patients with normal renal function receiving a 1-hour infusion. For a long-term infusion schedule, a dose increase may be necessary. The existing dosing strategies performed poorly for the children in our data set. For this subpopulation, our allometric scaling model may be most appropriate.

CONCLUSION

The two population pharmacokinetic models presented can be applied to estimate individual carboplatin clearance in high-dose chemotherapy based on body weight or height, infusion duration, and creatinine clearance. After prospective evaluation, our models may be suitable for dose adjustments.

Gemcitabine causes minimal modulation of carboplatin-DNA monoadduct formation and repair in bladder cancer cells

We are developing a method to identify cellular resistance to carboplatin by using accelerator mass spectrometry to measure carboplatin-DNA adducts formed from drug microdoses (∼1/100th the therapeutic dose). Such an approach would be particularly useful if it is still valid in combination chemotherapy. We examined whether the addition of gemcitabine, another chemotherapeutic drug, could influence carboplatin-DNA adduct levels. There were no substantial differences in the levels of carboplatin-DNA adducts in cells upon exposure to the carboplatin/gemcitabine combination at various doses and schedules. These data demonstrate that microdosing is feasible for the characterization of carboplatin resistance when given in combination with gemcitabine.

A phase I study of the safety and pharmacokinetics of the histone deacetylase inhibitor belinostat administered in combination with carboplatin and/or paclitaxel in patients with solid tumours

Background:

This phase I study assessed the maximum tolerated dose, dose-limiting toxicity (DLT) and pharmacokinetics of belinostat with carboplatin and paclitaxel and the anti-tumour activity of the combination in solid tumours.

Methods:

Cohorts of three to six patients were treated with escalating doses of belinostat administered intravenously once daily, days 1–5 q21 days; on day 3, carboplatin (area under the curve (AUC) 5) and/or paclitaxel (175 mg m⁻²) were administered 2–3 h after the end of the belinostat infusion.

Results:

In all 23 patients received 600–1000 mg m⁻² per day of belinostat with carboplatin and/or paclitaxel. No DLT was observed. The maximal administered dose of belinostat was 1000 mg m⁻² per day for days 1–5, with paclitaxel (175 mg m⁻²) and carboplatin AUC 5 administered on day 3. Grade III/IV adverse events were (n; %): leucopenia (5; 22%), neutropenia (7; 30%), thrombocytopenia (3; 13%) anaemia (1; 4%), peripheral sensory neuropathy (2; 9%), fatigue (1; 4%), vomiting (1; 4%) and myalgia (1; 4%). The pharmacokinetics of belinostat, paclitaxel and carboplatin were unaltered by the concurrent administration. There were two partial responses (one rectal cancer and one pancreatic cancer). A third patient (mixed mullerian tumour of ovarian origin) showed a complete CA-125 response. In addition, six patients showed a stable disease lasting ⩾6 months.

Conclusion:

The combination was well tolerated, with no evidence of pharmacokinetic interaction. Further evaluation of anti-tumour activity is warranted.

Phase 1b study of dulanermin (recombinant human Apo2L/TRAIL) in combination with paclitaxel, carboplatin, and bevacizumab in patients with advanced non-squamous non-small-cell lung cancer

PURPOSE

To determine the safety, pharmacokinetics (PK), and maximum-tolerated dose (MTD) up to a prespecified target dose of dulanermin in combination with paclitaxel, carboplatin, and bevacizumab (PCB) in patients with previously untreated, nonsquamous, stage IIIb (with pleural effusion)/IV or recurrent non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

In this phase 1b study, patients (n = 24) received PCB on day 1 of each 21-day cycle then dulanermin at 4 or 8 mg/kg/d for 5 consecutive days or 15 or 20 mg/kg/d for 2 consecutive days per assigned treatment cohort. Incidence of dose-limiting toxicities (DLTs), adverse events, and antidulanermin antibodies were assessed. PK parameters were recorded for each agent. Tumor response was measured by modified Response Evaluation Criteria in Solid Tumors.

RESULTS

Twenty-four patients received at least one dose of dulanermin plus PCB, six in each treatment cohort. There were no DLTs. An MTD was not reached, and the drug combination was well tolerated. Treatment-emergent adverse events were generally as expected for the PCB regimen. Adverse events attributed to dulanermin were grade 1/2; no significant hepatotoxicity occurred. There was minimal impact of PCB on the PK of dulanermin. There was one confirmed complete response and 13 confirmed partial responses. The overall response rate was 58% (95% CI, 37 to 78). Median progression-free survival was 7.2 months (95% CI, 4.7 to 10.3).

CONCLUSION

Dulanermin plus PCB was well tolerated with no occurrence of DLTs and demonstrated antitumor activity in this patient population. Dulanermin at 8 mg/kg/d for 5 days and 20 mg/kg/d for 2 days every 3 weeks in combination with PCB is being studied in a phase II trial.

Ovarian carcinoma cells with low levels of beta-F1-ATPase are sensitive to combined platinum and 2-deoxy-D-glucose treatment

We have here examined chemopotentiating effects of glycolysis inhibitor 2-deoxy-d-glucose (DG) in two epithelial ovarian carcinoma (EOC) cell lines and 17 freshly isolated ascitic EOC cell samples, and we identify low expression of the beta-F1-ATPase involved in mitochondrial ATP production as a candidate marker for sensitivity to this strategy. Although in the majority of samples, DG per se did not induce apoptosis, cotreatment with DG potentiated apoptosis and total antiproliferative effects of cisplatin and, to a lesser degree, carboplatin. In the cell lines, combination treatment with DG and cisplatin or carboplatin at noninhibitory concentrations prevented posttreatment regrowth in drug-free medium over a total of 5 days. DG per se allowed complete recuperation in drug-free medium. The more platinum-resistant a cell line was, the more sensitive it was to potentiation by DG and showed higher glucose uptake, DG-sensitive lactate production, and lower beta-F1-ATPase levels. In the ascitic samples, DG reduced the median IC(50) for cisplatin by 68% and, in the most sensitive samples, up to 90%, and DG-mediated potentiation correlated with low expression of beta-F1-ATPase. By contrast, cisplatin sensitivity did not correlate with beta-F1-ATPase levels. The findings validate targeting cancer cell glucose metabolism for potentiating platinum chemotherapy in EOC and indicate that reduced beta-F1-ATPase/oxidative phosphorylation distinguishes cells that are amenable to this strategy.

Carboplatin-induced alteration of the thiol homeostasis in the isolated perfused rat kidney

Carboplatin elicits minor side effects with respect to its first generation analogue cisplatin. Nevertheless, a dose-dependent nephrotoxicity of the drug has been reported to occur both in patients and in rats and a possible pathogenic role have been attributed to oxidative stress. We have studied the effect of carboplatin administration on the thiol/disulfide balance, on other biomarkers of oxidative stress and on antioxidant enzymes in the isolated perfused rat kidney. A 5-500microM carboplatin dose range did not alter renal function but significantly decreased levels of cysteine, glutathione and exposed protein sulfhydryl groups. Only a minimal increment in disulfides was observed, whereas malonyldialdehyde and protein carbonyls did not increase significantly. Among the antioxidant enzymes studied, only thioltransferase was inhibited by the treatment. Our data suggest that a minimal oxidative stress is present under our experimental conditions, thus indicating that platinum-based drugs do not produce significant amount of reactive oxygen species.

Evaluation of the Modified Diet in Renal Disease Equation for Calculation of Carboplatin Dose

Background:

Serum creatinine (SCr)-based formulas are used to estimate glomerular filtration rate (GFR) when calculating a dosage for carboplatin using the Calvert equation, but these formulas often underestimate measured GFR. The Modified Diet in Renal Disease (MDRD) equation appears to be a more accurate estimate of GFR in patients with chronic kidney disease, but this equation has not been studied extensively in patients with cancer.

Objective:

To determine the absolute difference between the dose of carboplatin administered (traditional SCr-based formulas used to estimate GFR) and the dose calculated using the MDRD equation to estimate GFR and compare the frequencies of thrombocytopenia, neutropenia, and dosage modifications between subjects in whom the difference in dose was 20% or more (divergent) or less than 20% (nondivergent).

Methods:

A retrospective analysis was conducted using data from patients who received carboplatin. Inclusion criteria were receipt of at least 2 doses of carboplatin, either as monotherapy or combination therapy, and documentation of desired area under the concentration-time curve (AUC). Patients were excluded if the baseline values needed to estimate GFR using the MDRD equation were not available. The absolute difference between the dose of carboplatin administered and that calculated using the MDRD equation was determined and, from this comparison, the subjects were divided into 2 groups (divergent vs nondivergent).

Results:

The medical records of 186 adults who received more than 2 doses of carboplatin were included in the analysis. The doses were divergent in 89 (48%) patients. The mean target AUC values were 5.3 mg/mUmin and 5.1 mg/mL/min in the divergent and nondivergent groups, respectively, and most patients received cytotoxic regimens with a relatively low risk of febrile neutropenia. The frequencies of neutropenia, thrombocytopenia, and dosage modifications were similar between the 2 groups. Use of the MDRD equation to calculate the carboplatin dosage did not appear to result in a change in the frequency of myelosuppression or the need for dose modifications compared with traditional SCr-based formulas.

Conclusions:

The traditional SCr-based formulas for the calculation of carboplatin dosage should be used to estimate carboplatin dose until more data become available regarding the use of the MDRD equation in this population.

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.

Multicenter phase I/II study of cetuximab with paclitaxel and carboplatin in untreated patients with stage IV non-small-cell lung cancer

PURPOSE

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors have demonstrated antitumor activity in patients with non-small-cell lung cancer (NSCLC). This study examined the safety profile of the monoclonal antibody EGFR inhibitor, cetuximab, when added to paclitaxel and carboplatin in untreated patients with stage IV NSCLC. Secondary objectives included efficacy and paclitaxel and carboplatin pharmacokinetics during cetuximab treatment.

PATIENTS AND METHODS

Patients with tumor evidence of EGFR by immunohistochemistry, performance status of 0 to 2, and measurable disease received paclitaxel 225 mg/m2 with carboplatin area under the curve = 6 on day 1 every 3 weeks. Cetuximab was administered at 400 mg/m2, 1 week before paclitaxel and carboplatin, then weekly at 250 mg/m2. The regimen continued until disease progression or intolerable toxicity.

RESULTS

Thirty-one of 32 enrolled patients were treated. The most common cetuximab toxicity was rash in 84% of patients (grade 3 in 13%). Pharmacokinetic sampling did not reveal an interaction between carboplatin, paclitaxel, and cetuximab. An objective response was observed in eight patients (26%). With a median follow-up of 19 months, the median time to progression was 5 months, median survival was 11 months, and the 1- and 2-year survival rates were 40% and 16%, respectively.

CONCLUSION

The combination of cetuximab, paclitaxel, and carboplatin was safe and well tolerated in this population of stage IV patients. The response rate, time to progression, and median survival were slightly superior to historical controls treated with paclitaxel and carboplatin alone. A randomized phase II trial has completed accrual.

High performance liquid chromatographic determination of platinum in blood and urine samples of cancer patients after administration of cisplatin drug using solvent extraction and N,N'-bis(salicylidene)-1,2-propanediamine as complexation reagent

A high performance liquid chromatographic (HPLC) procedure has been developed for the determination of cisplatin, based on the pre-column derivation of platinum(II) with reagent N,N'-bis(salicylidene)-1,2-propanediamine (H2SA2pn). The neutral platinum complex was extracted, concentrated in an organic solvent and then injected (5 microl) on a reverse phase HPLC column, Varian Micro-Pak SP C-18, 5 microm (150 mm x 4.0 mm i.d.). The complex was eluted isocratically using a ternary mixture of methanol/acetonitrile/water (40/30/30, v/v/v) at a flow rate of 1.0 ml/min and was determined by a UV detector set at 254 nm after elution. A detection limit was found to be 4.0 ng per injection. The amounts of platinum in blood serum and urine of cancer patients after administration of cisplatin were observed in a range of 221-298 ng/ml and 43-97 ng/ml with relative standard deviation (R.S.D.) of 3.6-4.6% and 3.5-4.8%, respectively. Preliminary metabolism profiles of Pt concentrations in blood and urine from the patients were established.

Analysis of cytotoxicities of platinum compounds

Extent of DNA platination, loss of cell viability, DNA fragmentation, and impairment of cellular mitochondrial oxygen consumption are measures of drug cytotoxicity. We measured and compared these effects for cisplatin, oxaliplatin and carboplatin. Because reaction with intracellular thiols may be responsible for drug resistance, we also determined the rates of Pt drug reactions with metallothionein. Jurkat cells were exposed at 37 degrees C to 25 microM Pt drugs for 3 h. Pt-DNA adducts were determined at the end of the incubation period by atomic absorption spectroscopy. Viability, DNA fragmentation, and cellular respiration (microM O2/min/10(6) cells) were determined 24 h post drug exposure. The average amount of Pt-DNA adducts (Pt atoms/10(6) nucleotides) produced by cisplatin was 43.4, by oxaliplatin 4.8 and by carboplatin 1.5. Cisplatin decreased the rate of respiration by approximately 63% and oxaliplatin by approximately 37%. DNA fragmentation by cisplatin and oxaliplatin was very similar. Carboplatin produced an unnoticeable effect on cellular respiration, and only approximately 10% of the DNA fragmentation was produced by cisplatin or oxaliplatin. Although, for a given drug, all four measures of cytotoxicity were proportional, this did not hold for comparisons between the drugs. The rate constants (M-1 s-1) for reaction of cisplatin, oxaliplatin and carboplatin with Cd/Zn thionein were 0.75, 0.44 and 0.012, respectively. For comparison, the rate constants (M-1 s-1) for reaction of cisplatin, oxaliplatin and carboplatin with glutathione were 0.027, 0.038 and 0.0012, respectively. The low reactivity of carboplatin with metallothionein and glutathione suggests that its low cytotoxic activities are not due to reaction of Pt2+ with cellular thiols. Despite a tenfold difference in Pt-DNA adducts between cisplatin and oxaliplatin, the cytotoxicities of these compounds are very similar, suggesting that oxaliplatin lesions are more potent than cisplatin lesions. The results demonstrate a large influence of the ligands occupying Pt coordination spheres on the chemical and biologic activities of Pt drugs.