Multicenter Phase II Clinical Trial of Isolated Lung Perfusion in Patients With Lung Metastases.

BACKGROUND: Up to 66% of patients show local pulmonary disease progression after pulmonary metastasectomy. Regional treatment with isolated lung perfusion (ILuP) may improve local control with minimal systemic adverse effects. The aims of this study were to evaluate local and distant control after ILuP, determine the effect on overall survival compared with historical controls, and confirm the safety and feasibility of ILuP. METHODS: A total of 107 patients with resectable pulmonary metastases of colorectal carcinoma, osteosarcoma, and soft-tissue sarcoma were included in a prospective phase II study of pulmonary metastasectomy combined with ILuP with 45 mg melphalan at 37°C. Local and distant control, overall survival, lung function, and 90-day mortality and morbidity were monitored. RESULTS: We report 0% mortality, low morbidity, and no long-term pulmonary toxicity. For colorectal carcinoma, median time to local pulmonary progression, median time to progression, and median survival time were 31, 14, and 78 months, respectively. Median time to local progression was not reached for sarcoma, whereas median time to progression and median survival time were 13 and 39 months, respectively. The 5-year disease-free rate and pulmonary progression-free rate were 26% and 44% for colorectal carcinoma and 29% and 63% for sarcoma, respectively. CONCLUSIONS: ILuP with melphalan combined with metastasectomy is feasible and safe. Compared with historical controls, favorable results were obtained in this phase II study for local control. Further evaluation of locoregional lung perfusion techniques with other chemotherapeutic drugs is warranted.

Selective pulmonary artery perfusion with melphalan is equal to isolated lung perfusion but superior to intravenous melphalan for the treatment of sarcoma lung metastases in a rodent model.

OBJECTIVES: Isolated lung perfusion (ILuP) and selective pulmonary artery perfusion (SPAP) are experimental surgical techniques to deliver high-dose chemotherapy selectively to the lung for the treatment of lung metastases. ILuP with melphalan (MN) has shown to be feasible in clinical studies but can only be used once because it is invasive. SPAP as an endovascular technique can be repeated several times, but no results have been reported so far. Pharmacokinetics and efficacy of SPAP with MN were studied in a rodent lung metastasis model and compared it with ILuP and intravenous (IV) therapy. METHODS: Pharmacokinetics: forty-five Wag-Rij rats were randomized into three groups: IV 0.5 mg MN, ILuP 0.5 mg MN and SPAP 0.5 mg MN. Every treatment group was again randomized in three groups: 15 min treatment, 30 min treatment and 30 min treatment with 30 min reperfusion. Blood and tissue samples were taken for MN concentrations. EFFICACY: twenty-five Wag-Rij rats were randomized into five groups: control, sham thoracotomy, IV 0.5 mg MN, ILuP 0.5 mg MN and SPAP 0.5 mg MN. At day 0, bilateral lung metastases were induced, and treatment followed at day 7. At day 28, rats were sacrificed and pulmonary metastases counted. Survival: thirty Wag-Rij rats were randomized into five groups: control, sham ILuP, IV 0.5 mg MN, ILuP 0.5 mg MN, SPAP 0.5 mg MN. At day 0, left-sided lungmetastases were induced with treatment at day 7. Endpoints were death due to disease or survival up to 90 days. RESULTS: Pharmacokinetics: SPAP and ILuP resulted in significantly higher left lung MN concentrations compared with IV (P = 0.05). EFFICACY: SPAP (30 ± 22 nodules) and ILuP (20 ± 9 nodules) resulted in significantly less nodules compared with IV (113 ± 17 nodules; P < 0.01). Survival: median survival of SPAP (74 ± 8 days) was equal to ILuP MN (71 ± 10 days) but significantly longer compared with IV (54 ± 7 days; P < 0.01 both). CONCLUSIONS: SPAP with MN for the treatment of sarcoma lung metastases in rats is equally effective to ILuP but resulted in a significantly better survival compared with IV MN. As SPAP can be applied as a minimally invasive endovascular procedure, continued research with this technique is warranted.

Isolated hypoxic hepatic perfusion with retrograde outflow in patients with irresectable liver metastases; a new simplified technique in isolated hepatic perfusion.

BACKGROUND: Isolated hepatic perfusion with high-dose chemotherapy is a treatment option for patients with irresectable metastases confined to the liver. Prolonged local control and impact on survival have been claimed. Major drawbacks are magnitude and costs of the procedure. We developed an isolated hypoxic hepatic perfusion (IHHP) with retrograde outflow without the need for a heart-lung machine. PATIENTS AND METHODS: Twenty-four consecutive patients with irresectable metastases of various origins were treated. IHHP inflow was via the hepatic artery, outflow via the portal vein with occlusion of the retrohepatic caval vein. Radiolabeled albumine was used for leakage monitoring. Melphalan was used at 1-2 mg/kg. A 25-minute perfusion period was followed by a complete washout. Local and systemic melphalan concentrations were determined. RESULTS: Compared with oxygenated classical IHP, the IHPP procedure reduced operation time from >8 h to 4 hours, blood loss from >4000 to 900 cc and saved material and personnel costs. Leakage was 0% with negligible systemic toxicity and 0% perioperative mortality. Tumor response: complete response (CR) in 4%, partial response (PR) in 58%, and stable disease (SD) in 13%. Median time to progression was 9 months (2-24 months); pharmacokinetics demonstrated intrahepatic melphalan concentrations more than 9 fold higher than postperfusion systemic concentrations. CONCLUSIONS: IHPP is a relatively simple procedure with reduced costs, reduced blood loss, no mortality, limited toxicity, and response rates comparable to classic IHP. The median duration of 9 months of tumor control should be improved. Hereto, vasoactive drugs, will be explored in further studies.

Pharmacokinetics of gemcitabine when delivered by selective pulmonary artery perfusion for the treatment of lung cancer.

Lung cancer represents a major health problem. Cytostatic and radiotherapeutic treatment is limited because of dose-limiting systemic toxicity and surgery as a result of its invasive nature. Therefore, we developed a catheterization model of selective pulmonary artery perfusion (SPAP) combining the properties of isolated lung perfusion and i.v. treatment to achieve higher local drug levels and equivalent systemic exposure. Sixteen pigs underwent SPAP using a clinically applied dose of gemcitabine (1 g/m(2)). They furthermore underwent thoracotomy for tissue sampling. Three groups were treated with SPAP for 2 min with normal pulmonary blood flow, 50 and 90% flow reduction. Another group had SPAP for 10 min with normal blood flow. All the SPAP groups underwent catheterization of the left pulmonary artery. An additional group (n = 4) was infused i.v. for 30 min using the same dose. Concentrations were analyzed with analysis of variance. Pulmonary peak concentrations (p = 0.01) and areas under the curve (AUC) (p = 0.001) of SPAP for 2 and 10 min were significantly higher compared with i.v., whereas SPAP for 10 min resulted in the highest AUC (p = 0.045) compared with SPAP for 2 min. Flow reduction during SPAP resulted in inhomogeneous distribution. Liver levels, AUC (serum), and wet-to-dry ratios of all the SPAP groups were not significantly different compared with i.v. SPAP resulted in higher lung concentrations, whereas systemic exposure was comparable with i.v. Therefore, we advocate SPAP as a new method to be tested clinically to achieve down-staging of the tumor and lymph node status in lung cancer.

Simultaneous determination of AMN107 and Imatinib (Gleevec, Glivec, STI571) in cultured tumour cells using an isocratic high-performance liquid chromatography procedure with UV detection.

A reversed phase high-performance liquid chromatographic (HPLC) method with UV detection was developed for the simultaneous determination of imatinib (Gleevec, Glivec, STI571) and AMN107 in cultured tumour cells, using clozapine as an internal standard. The compounds of interest were extracted by liquid-liquid extraction using TOXI-TUBES((R)) A extraction tubes. Chromatographic separation was performed on a Phenomenex Gemini C18 reversed phase column (150 mm x 2.0 mm, 5 microm particle size), using a mixture of 65% CH(3)OH (methanol) and 35% NH(4)Ac (Ammonium acetate) buffer (20mM, pH 10). Separation was achieved under isocratic conditions at a flow rate of 0.5 ml/min. Imatinib, clozapine and AMN107 are detected by UV detection at 260 nm. Calibration curves were linear from 50 to 7500 ng/ml with correlation coefficients (r(2)) better than 0.998. The limit of quantitation (LOD) was 50 ng/ml. The method has been successfully applied to a cellular kinetics study.

Decreased response rates by the combination of histamine and IL-2 in melphalan-based isolated limb perfusion.

Histamine (Hi) combined to melphalan in a rat experimental model of isolated limb perfusion (ILP) for lower limb soft tissue sarcoma, resulted in overall response rates (OR) of 66%. Likewise, ILP with interleukin-2 (IL-2) resulted in OR of 67%, when combined to melphalan, in the same experimental model. In systemic immunotherapy, the combination of IL-2 and Hi has been used for solid tumor treatment based on immunomodulatory effects. In this study, we used our well-established ILP experimental model to evaluate whether the synergistic effect between the two drugs seen in the systemic setting, could further improve response rates in a loco-regional setting. Histological evaluation was done directly and 24 h after ILP. Melphalan uptake by tumor and muscle were measured. Hi and IL-2 together, combined to melphalan in the ILP led to OR of only 28%. Histology of tumors demonstrated partial loss of Hi-induced hemorrhagic effect when IL-2 was present. Melphalan accumulation in the tumor when both Hi and IL-2 were added (3.1-fold) was very similar to accumulation with Hi only (2.8-fold), or IL-2 only (3.5-fold) combined to melphalan. In vitro there was no synergy between the drugs. In conclusion there was a negative synergistic effect between IL-2 and Hi in the regional setting.

Association of enzyme and transporter genotypes with the pharmacokinetics of imatinib.

OBJECTIVE: Our objective was to explore the relationships between imatinib pharmacokinetics and 9 allelic variants in 7 genes coding for adenosine triphosphate-binding cassette transporters (ABCB1 and ABCG2) and enzymes (cytochrome P450 [CYP] 2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5) of putative relevance for imatinib. METHODS: Imatinib transport in vitro was studied by use of human embryonic kidney 293 cells transfected with wild-type ABCG2 and an ABCG2 Q141K clone. Steady-state pharmacokinetics of imatinib was obtained in 82 patients with gastrointestinal stromal tumors treated with oral imatinib at doses ranging from 100 to 1000 mg/d. Genotyping was carried out via direct sequencing or restriction fragment length polymorphism-based techniques. RESULTS: Human embryonic kidney 293 cells transfected with ABCG2 Q141K exhibited greater drug accumulation in vitro in comparison with cells expressing wild-type ABCG2 (P = .028). However, pharmacokinetic parameters of imatinib in vivo were not statistically significantly different in 16 patients who were heterozygous for ABCG2 421C>A compared with 66 patients carrying the wild-type sequence (P = .479). The apparent oral clearance of imatinib was potentially reduced in individuals with at least 1 CYP2D6*4 allele (median, 7.78 versus 10.6 L/h; P = .0695). Pharmacokinetic parameters were not related to any of the other multiple-variant genotypes (P >or= .230), possibly because of the low allele frequencies. CONCLUSIONS: This study indicates that common genetic variants in the evaluated genes have only a limited impact on the pharmacokinetics of imatinib. Further investigation is required to quantitatively assess the clinical significance of homozygous variant ABCG2 and CYP2D6 genotypes in patients treated with imatinib.

Modified approach of administering cytostatics to the lung: more efficient isolated lung perfusion.

BACKGROUND: Isolated lung perfusion (ILuP) is an experimental technique for the treatment of pulmonary metastases. We hypothesized that part of the drug taken up by the lung during ILuP is washed out during the flush procedure. Therefore, we investigated gemcitabine uptake at different inflow concentrations, and the effect of delayed clamp release after ILuP on lung levels was studied. METHODS: Thirty rats had ILuP during 30 minutes using gemcitabine perfusate levels of 1.3, 2.7, 4.0, 5.3, and 6.7 mg/mL. Another 37 rats underwent ILuP with gemcitabine perfusate levels of 6.7 mg/mL during 6 minutes followed by a 5-minute flush and 30 or 60 minutes of reperfusion, while two other groups had ILuP and delayed clamp release for 30 or 60 minutes followed by a 5-minute flush. All effluent and lung samples were stored for later analysis. Results were evaluated using Friedmann two-way analysis and two-way analysis of variance. RESULTS: At 6 minutes, steady-state of gemcitabine uptake was achieved for all inflow concentrations and a linear relation (r = 0.933, p < 0.0001) between effluent and lung levels was observed. Delayed clamp release resulted in significantly higher lung levels compared with immediate restoration of blood circulation after ILuP (456% at 30 minutes and 828% at 60 minutes). CONCLUSIONS: Effective gemcitabine lung levels are already achieved after 6 minutes of ILuP with 6.7 mg/mL followed by delayed clamp release during 30 minutes instead of the clinically applied 30 minutes ILuP.

Everolimus alters imatinib blood partition in favour of the erythrocyte.

The signal transduction inhibitor imatinib is one of the latest breakthroughs in cancer pharmacotherapy. It is administered orally over prolonged periods of time for the treatment of gastro-intestinal stromal tumours. Routine therapeutic drug monitoring of blood plasma versus red blood cells over several years by liquid chromatography coupled tandem mass spectrometry has high-lighted a very intriguing phenomenon. Imatinib plasma availability decreases dramatically owing to a significant shift in the partition ratio of red blood cells versus plasma. The shift is enforced by combination with everolimus, another signal transduction inhibitor. These data warrant routine erythrocyte versus plasma monitoring to prevent unexpected alterations in drug efficacy during long-term treatment.

Cellular uptake of the tyrosine kinase inhibitors imatinib and AMN107 in gastrointestinal stromal tumor cell lines.

Imatinib and AMN107 are protein tyrosine kinase inhibitors which reduce KIT autophosphorylation with similar potency. This report describes the cellular uptake of these compounds in two human gastrointestinal stromal tumor (GIST)-derived cell lines (GIST882 and GIST GDG1), which both express constitutively activated KIT. In GIST882 and GIST GDG1 cell lines, HPLC analysis revealed AMN107 intracellular concentrations to be 7- and 10-fold greater than those of imatinib. These data indicate either increased cellular uptake or decreased cellular efflux of AMN107 when compared to imatinib in GIST cell lines. The finding suggests that AMN107 might be less susceptible to transport-driven imatinib resistance. The stable and increased exposure of GIST cells to a highly active AMN107 agent could be important in the treatment of imatinib-resistant GIST patients in whom resistance has developed as a result of changes in cellular transport mechanisms for which AMN107 is not a substrate.

Imatinib (Gleevec, Glivec) tumour tissue analysis by measurement of sediment and by liquid chromatography tandem mass spectrometry.

The analysis of the signal transduction inhibitor imatinib in patient tumour tissue using LC and MS/MS is described. The anticancer agent is eluted over RP-C18 within 2 mm together with its internal standard STI571-d8. Calibration curves were prepared in red blood cells (RBC). For quantitative isolation of the RBC, measurement of sediment was applied. There were no indications of signal suppression by substances originating in the biological matrix. The limit of determination in tumour tissue was in the range of those recorded for RBC and plasma. The assay is selective and sensitive, with its robustness favouring the experimental application in clinical oncology and its routine use in animal experiments. The LOD was 4.5 ng per gram in tumour tissue.

Proteomics in cancer research: methods and application of array-based protein profiling technologies.

With the human genome sequence now determined, the field of molecular medicine is moving beyond genomics to proteomics, the large-scale analysis of proteins. It is now possible to examine the expression of more than 1000 proteins using mass spectrometry technology coupled with various separation methods. Microarray technology is a new and efficient approach, for extracting relevant biomedical data and has a wide range of applications. It provides a versatile tool to study protein-protein, protein-nucleic acid, protein-lipid, enzyme-substrate and protein-drug interactions. This review paper will explore the key themes in proteomics and their application in clinical cancer research.

In vitro partition of docetaxel and gemcitabine in human volunteer blood: the influence of concentration and gender.

We have performed in vitro incubations of blood from male and female volunteers with gemcitabine and docetaxel alone, and in combination, at different concentration gradients in order to investigate changes in partition between red blood cells (RBCs), total plasma and the free fraction. After extraction and sample pre-treatment, a validated high-performance liquid chromatography method followed by UV detection was used to determine the concentrations of both drugs in the different blood constituents. The partition ratio [the concentration in the erythrocytes divided by the concentration in plasma (E/P)] was calculated. The partition ratio of docetaxel varied from 0.02 to 1.44 (mean 0.35), reflecting its relatively low affinity for RBCs, probably because of its high plasma protein binding (more than 98%). For gemcitabine, the partition ratio varied from 1 to 5, reflecting a high affinity for RBCs (less than 10% plasma protein bound). The partition ratios of both drugs increased significantly with higher whole-blood concentrations, favoring uptake in the erythrocytes when plasma protein binding is saturated. Combination incubations showed a complex and unexplained interaction between gender and the influence of docetaxel on the partition of gemcitabine. We conclude that the incorporation of drugs into the RBC pool may be important for transportation to tumor tissue and efficacy. In combination, one anti-cancer agent can alter the partition ratios of other anti-cancer agents.

In vitro partition of irinotecan (CPT-11) in human volunteer blood: the influence of concentration, gender and smoking.

We have performed in vitro incubations of blood from male and female volunteers, smokers and non-smokers, with irinotecan at a gradient of different concentrations in order to investigate changes of partition between red blood cells (RBCs), total plasma and the free fraction. Since irinotecan (CPT-11) is not metabolized in vitro, there is no data available on its active metabolite SN-38. After extraction and sample pre-treatment, a validated high-performance liquid chromatography method followed by fluorescence detection was used to determine the concentration of the drug in the different blood constituents. The partition ratio [the concentration in the erythrocytes divided by the concentration in plasma (E/P)] was calculated. The partition ratio of CPT-11 varied from 0.7 to 2.8, reflecting its relatively high affinity for the erythrocyte, probably because of its only moderate plasma protein binding (65%). The partition ratios increased significantly with higher whole-blood concentrations, favoring uptake in the erythrocytes when plasma protein binding is saturated. No gender difference was detected, but we found relatively more CPT-11 in the erythrocytes of non-smokers compared to smokers. The incorporation of drugs into the RBC pool may be important for transportation to tumor tissue and efficacy. Smoking can have a significant influence on drug partition in the blood.

Chronic imatinib mesylate exposure leads to reduced intracellular drug accumulation by induction of the ABCG2 (BCRP) and ABCB1 (MDR1) drug transport pumps.

Imatinib mesylate is a selective tyrosine kinase inhibitor that is successfully used in the treatment of Philadelphia-positive chronic and acute leukaemia's, and gastrointestinal stromal tumors. We investigated whether the intended chronic oral administration of imatinib might lead to the induction of the intestinal ABC transport proteins ABCB1, ABCC1 (MRP1), ABCC2 (MRP2) and ABCG2. Using Caco2 cells as an in vitro model for intestinal drug transport, we found that continuous exposure (up to 100 days) with imatinib (10 microM) specifically upregulates the expression of ABCG2 (maximal approximately 17-fold) and ABCB1 (maximal approximately 5-fold). The induction of gene expression appeared to be biphasic in time, with a significant increase in ABCG2 and ABCB1 at day 3 and day 25, respectively, and was not mediated through activation of the human orphan nuclear receptor SXR/NR1I2. Importantly, chronic imatinib exposure of Caco2 cells resulted in a approximately 50% decrease in intracellular accumulation of imatinib, probably by enhanced ABCG2- and ABCB1-mediated efflux, as a result of upregulated expression of these drug pumps. Both ABCG2 and ABCB1 are normally expressed in the gastrointestinal tract and it might be anticipated that drug-induced upregulation of these intestinal pumps could reduce the oral bioavailability of imatinib, representing a novel mechanism of acquired pharmacokinetic drug resistance in cancer patients that are chronically treated with imatinib.

Anterograde versus retrograde isolated lung perfusion with melphalan in the WAG-Rij rat.

OBJECTIVE: Isolated lung perfusion (ILuP) is an experimental technique currently tested to increase the 5-year survival of 40% after surgical resection of pulmonary metastases from certain solid tumors. The standard technique of anterograde perfusion was compared with retrograde isolated lung perfusion in which the drug is introduced through the pulmonary veins while the effluent is collected from the pulmonary artery. Since the lung has a dual arterial circulation through the pulmonary artery and bronchial circulation, perfusion through the pulmonary veins can result in a more homogeneous distribution throughout the lung with subsequent higher melphalan concentration. METHODS: We randomized 20 rats into two groups. Group one underwent anterograde isolated left lung perfusion while group two underwent retrograde isolated left lung perfusion. A dose of 2 mg/kg melphalan (MN) was administered to the lung at a flow of 0.5 mL/min during 30 min, followed by a 5-min washout with buffered hetastarch (BHE). The final melphalan lung concentration (FMLC) was determined in the hilum, at the apex, the mid-periphery and the base of the lung. Statistical analysis was done with an unpaired student's t-test. RESULTS: Retrograde left ILuP resulted in a higher FMLC in the hilum (P<0.0001) and in the base of the lung (P=0.03), while anterograde ILuP induced a higher concentration at the apex of the lung (P=0.04). No difference was seen in the mid-peripheral area of the lung (P=0.92). CONCLUSIONS: In this experimental study, retrograde perfusion seems to increase final melphalan lung concentration in hilar and basal regions of the lung compared to anterograde perfusion.

Regional differences of melphalan lung levels after isolated lung perfusion in the rat.

BACKGROUND: Efficacy studies of isolated lung perfusion (ILuP) with melphalan showed superior results compared to intravenous therapy. However, the influence of pharmacokinetic parameters on the final melphalan lung concentration (FMLC) is unknown. In this study, we studied the impact of three different perfusion parameters on the FMLC in different areas of the lung. MATERIAL AND METHODS: Fifty-four rats were randomized into nine groups. Each group underwent ILuP with variation of perfusion duration (15, 30, and 60 min), the flow (0.125, 0.25, and 0.5 ml/min), concentration (8.3, 16.7, 33.3, 66.7, and 133.3 microg/ml) and the resulting dose (maximum 4 mg/kg). Lung samples were taken from the hilum and at the periphery of the lung (apex, base). Additional samples were taken to evaluate wet-to-dry ratio (W/D-ratio). Multiple linear regression and Student's t test were used for analysis. Significance was defined as a P

The relevance of therapeutic drug monitoring in plasma and erythrocytes in anti-cancer drug treatment.

Therapeutic drug monitoring generally focuses on the plasma compartment only. Differentiation between the total plasma concentration and the free fraction (plasma water) has been described for a number of limited drugs. Besides the plasma compartment, blood has also a cellular fraction which has by far the largest theoretical surface and volume for drug transport. It is with anti-cancer drugs that major progress has been made in the study of partition between the largest cellular blood compartment, i.e., erythrocytes, and the plasma compartment. The aim of the present review is to detail the progress made in predicting what a drug does in the body, i.e., pharmacodynamics including toxicity and plasma and/or red blood cell concentration monitoring. Furthermore, techniques generally used in anti-cancer drug monitoring are highlighted. Data for complex Bayesian statistical approaches and population kinetics studies are beyond the scope of this review, since this is generally limited to the plasma compartment only.

Synergistic antitumor activity of histamine plus melphalan in isolated limb perfusion: preclinical studies.

BACKGROUND: We have previously shown how tumor response of isolated limb perfusion (ILP) with melphalan was improved when tumor necrosis factor alpha (TNF-alpha) was added. Taking into account that other vasoactive drugs could also improve tumor response to ILP, we evaluated histamine (Hi) as an alternative to TNF-alpha. METHODS: We used a rat ILP model to assess the combined effects of Hi and melphalan (n = 6) on tumor regression, melphalan uptake (n = 6), and tissue histology (n = 2) compared with Hi or melphalan alone. We also evaluated the growth of BN-175 tumor cells as well as apoptosis, necrosis, cell morphology, and paracellular permeability of human umbilical vein endothelial cells (HUVECs) after Hi treatment alone and in combination with melphalan. RESULTS: The antitumor effect of the combination of Hi and melphalan in vivo was synergistic, and Hi-dependent reduction in tumor volume was blocked by H1 and H2 receptor inhibitors. Tumor regression was observed in 66% of the animals treated with Hi and melphalan, compared with 17% after treatment with Hi or melphalan alone. Tumor melphalan uptake increased and vascular integrity in the surrounding tissue was reduced after ILP treatment with Hi and melphalan compared with melphalan alone. In vitro results paralleled in vivo results. BN-175 tumor cells were more sensitive to the cytotoxicity of combined treatment than HUVECs, and Hi treatment increased the permeability of HUVECs. CONCLUSIONS: Hi in combination with melphalan in ILP improved response to that of melphalan alone through direct and indirect mechanisms. These results warrant further evaluation in the clinical ILP setting and, importantly, in organ perfusion.

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.