Combination effects of platinum drugs and N1, N11 diethylnorspermine on spermidine/spermine N1-acetyltransferase, polyamines and growth inhibition in A2780 human ovarian carcinoma cells and their oxaliplatin and cisplatin-resistant variants.

PURPOSE: To understand the mechanisms behind platinum drug/DENSPM-induced inhibition of cancer cell growth, we compared the effects of oxaliplatin and cisplatin when combined with DENSPM on the induction of SSAT mRNA, activity, polyamines and cell growth in A2780 human ovarian carcinoma cells and their oxaliplatin- and cisplatin-resistant variants A2780/C10B and A2780/CP, respectively. METHODS: Parental and Pt-resistant cells were treated with platinum agent alone, DENSPM alone or combination (10 µM each, 20 h). QRT-PCR, radioactive product measurement and HPLC were used for mRNA, activity and polyamine pools, respectively; drug interaction on cell growth was by SRB and isobologram analysis. RESULTS: Both platinum agents induced SSAT mRNA in parental A2780 cells, but not in resistant cells. Platinum drug/DENSPM combinations produced high levels of SSAT activity in parental cells with significant depletion of spermine and spermidine, but not in resistant cells. Co-treatment with platinum agents increased the levels of DENSPM in all cell lines. Oxaliplatin/DENSPM combination was superior to cisplatin/DENSPM in the inhibition of cell growth in parental cells. No synergy was observed in the resistant cells. CONCLUSIONS: Increased DENSPM levels following co-treatment with Pt agents enhances the translation and stability of SSAT protein leading to polyamine pool depletion, facilitating more Pt-DNA adduct formation in parental cells. Oxaliplatin/DENSPM combination is superior to cisplatin/DENSPM in cell growth inhibition as DACH-Pt DNA adducts are cytotoxic even at relatively fewer numbers. Reduced platinum uptake in Pt-resistant cells contributes to reduced SSAT mRNA induction and absence of synergy when combined with DENSPM.

Characterization of Pt-, Pd-spermine complexes for their effect on polyamine pathway and cisplatin resistance in A2780 ovarian carcinoma cells.

We have previously showed that platinum drugs up-regulate SSAT and SMO and down-regulate ODC and SAMDC in the polyamine pathway. Several studies including our own established that platinum drugs combined with polyamine analog DENSPM produces synergistic increase in SSAT activity with polyamine depletion. Since polyamine pathway is an important therapeutic target, we investigated whether agents containing both platinum and polyamines have similar effects on the polyamine pathway. Two complexes i) Pt-spermine with two cisplatin molecules linked to a spermine in the center and ii) Pd-spermine with similar structure i, but Pd (II) substituted for Pt (II) were analyzed with respect to their effect on the expression of genes in polyamine pathway, SSAT and SMO protein expression, SSAT activity and polyamine pools. Pt-, Pd-spermine complexes induced significant down-regulation of SMO, arginase 2 and NRF-2, with no change in SSAT, while cisplatin as a single agent or in combination with DENSPM induced significant up-regulation of SSAT and SMO. The SSAT activity was not induced by either Pt- or Pd-spermine in A2780 cells; SMO protein levels were significantly elevated compared to the no-drug control and to a similar extent as cisplatin/DENSPM. The Pd-spm treatment induced a fall in putrescine levels to 33%, spermidine to 62% and spermine to 72% while Pt-spm did not induce such a decline. Comparative cytotoxicity studies in A2780 cells indicated the potency to be cisplatin> Pd-Spm>Pt-Spm. Although both complexes exhibit a lower potency, the degree of resistance itself is much lower for Pt-spermine and Pd-spermine in that order (2.5 and 7.5, respectively) compared to cisplatin ( approximately 12) as tested in cisplatin resistant A2780/CP cells. These studies suggest that Pd (II)-polyamine complexes may constitute a promising group of inorganic compounds for further studies in the development of novel chemotherapy/adjuvant chemotherapy strategies.

Thoracoscopic organ suffusion for regional lung chemotherapy (preliminary results).

BACKGROUND: After promising preclinical studies using a thoracoscopic regional lung chemotherapy technique less morbid than open perfusion methods, we initiated a Phase I clinical study. METHODS: Four performance status 0 to 1 patients with oligometastatic stage IV lung cancer underwent unilateral thoracoscopic lung suffusion targeting the bulk of primary disease and regional lymph nodes. We used the term suffusion (permeation of an organ) to describe the total lung distribution of chemotherapy afforded by venous distention akin to retrograde cardioplegia physiology. This was obtained by temporary thoracoscopic pulmonary vein occlusions and fluoroscopy-guided transfemoral intravascular balloon occlusion, drainage, and cisplatin distention of the main pulmonary artery. Single-lung ventilation allowed atelectasis that helped to drain the blood under pulmonary artery occlusion, then cisplatin (5% systemic dose) was instilled during venous occlusion and lung reexpansion. Chemotherapy dwelled for 30 minutes before lung reperfusion. RESULTS: All four suffusions were successful (three right, one left). Cisplatin remained concentrated in the pulmonary circulation by the end of the dwell (1,124 versus 236 ng/mL systemic). There were no changes in the postsuffusion pulmonary function tests or lung perfusion scans. All patients were discharged early (24 to 48 hours) without chest tubes, began standard chemotherapy without delay, and completed follow-up. After two systemic chemotherapeutic cycles primary tumors had volume reductions of 96%, 88%, 64%, and 14%, with the latter showing a 100% volume increase in a nonsuffused osseous metastasis. CONCLUSIONS: Our initial clinical experience of thoracoscopic lung suffusion suggests that this approach is safe and merits future study with higher dose levels.

Phase I evaluation of carboplatin by use of a dosing strategy based on a targeted area under the platinum concentration-versus-time curve and individual glomerular filtration rate in cats with tumors.

OBJECTIVE: To determine whether a carboplatin dose calculation that is based on a targeted area under the concentration-versus-time curve (AUC(Target)) and individual glomerular filtration rate (GFR) accurately predicts carboplatin-associated myelotoxicoses in tumor-bearing cats, and to determine the maximum tolerated AUC(Target). ANIMALS: 32 cats with tumors. PROCEDURES: In each cat, plasma clearance of technetium Tc 99m-labeled diethylenetriaminepentaacetic acid was measured to assess GFR. Carboplatin was administered IV. The dose was calculated by use of an equation as follows: Dose = AUC(Target) x 2.6 x GFR x body weight. Initial AUC(Target) was 2.0 min.mg.mL(-1) and was increased in increments of 0.50 min.mg.mL(-1) in cohorts of 3 cats. To assess myelotoxic effects, CBCs were performed weekly for > or = 4 weeks. Following identification of the maximum tolerated AUC(Target), additional cats were treated at that AUC(Target) and plasma platinum concentrations were measured in 6 cats. RESULTS: The AUC(Target) values ranged from 2.0 to 3.0 min.mg.mL(-1). Neutropenia was the dose-limiting toxicosis, and the maximum tolerated AUC(Target) was 2.75 min.mg.mL(-1). Nineteen cats received this dose of carboplatin; 13 became neutropenic, but only 1 developed severe neutropenia (< 500 neutrophils/microL), and none had neutropenia-associated clinical signs. In the cats that had plasma platinum concentration determined, the difference between AUC(Target) and the measured value ranged from -0.23 to 0.31 min.mg.mL(-1) (median, 0.20 min.mg.mL(-1)). CONCLUSIONS AND CLINICAL RELEVANCE: In cats, carboplatin-associated myelotoxicoses were accurately and uniformly predicted by use of the proposed dosing strategy. The maximum tolerated AUC(Target) for a single dose of carboplatin was 2.75 min.mg.mL(-1).

A phase I, pharmacokinetic and pharmacodynamic study on vorinostat in combination with 5-fluorouracil, leucovorin, and oxaliplatin in patients with refractory colorectal cancer.

PURPOSE: We conducted a phase I study to determine the maximum tolerated dose of vorinostat in combination with fixed doses of 5-fluorouracil (FU), leucovorin, and oxaliplatin (FOLFOX). EXPERIMENTAL DESIGN: Vorinostat was given orally twice daily for 1 week every 2 weeks. FOLFOX was given on days 4 and 5 of vorinostat. The vorinostat starting dose was 100 mg twice daily. Escalation occurred in cohorts of three to six patients. Pharmacokinetics of vorinostat, FU, and oxaliplatin were studied. RESULTS: Twenty-one patients were enrolled. Thrombocytopenia, neutropenia, gastrointestinal toxicities, and fatigue increased in frequency and severity at higher dose levels of vorinostat. Two of 4 evaluable patients at dose level 4 (vorinostat 400 mg orally twice daily) developed dose-limiting fatigue. One of 10 evaluable patients at dose level 3 (vorinostat 300 mg orally twice daily) had dose-limiting fatigue, anorexia, and dehydration. There were significant relationships between vorinostat dose and the area under the curve on days 1 and 5 (Pearson, < 0.001). The vorinostat area under the curve increased (P = 0.005) and clearance decreased (P = 0.003) on day 5 compared with day 1. The median C(max) of FU at each dose level increased significantly with increasing doses of vorinostat, suggesting a pharmacokinetic interaction between FU and vorinostat. Vorinostat-induced thymidylate synthase (TS) modulation was not consistent; only two of six patients had a decrease in intratumoral TS expression by reverse transcription-PCR. CONCLUSIONS: The maximum tolerated dose of vorinostat in combination with FOLFOX is 300 mg orally twice daily x 1 week every 2 weeks. Alternative vorinostat dosing schedules may be needed for optimal down-regulation of TS expression.

Expression of Na,K-ATPase-beta(1) subunit increases uptake and sensitizes carcinoma cells to oxaliplatin.

PURPOSE: The ovarian carcinoma subline A2780/C10B (C10B) is an oxaliplatin resistant clone derived from the human ovarian carcinoma cell line A2780. The C10B cells are characterized by mesenchymal phenotype, decreased platinum uptake and increased glutathione levels (Hector et al. in Cancer Lett 245:195-204, 2007; Varma et al. in Oncol Rep 14:925-932, 2005). Na,K-ATPase-beta subunit (Na,K-beta(1)) functions as a cell-cell adhesion molecule in epithelial cells and is reduced in a variety of carcinoma cells that show mesenchymal phenotype. The purpose of this study is to evaluate the relationship between Na,K-beta expression and sensitivity to oxaliplatin. METHODS: Cell lines used include A2780, C10B, C10B transfected with Na,K-beta(1) (C10B-Na,K-beta) and a canine kidney carcinoma cell line MSV-MDCK also transfected with Na,K-beta(1) (MSV-MDCK-beta subunit). Cytotoxicity studies were performed by sulforhodamine-blue assay. The Na,K-alpha(1) and Na,K-beta(1) subunit localization and expression were by immunofluorescence microscopy and Western blot analysis. Platinum accumulation measurements were by atomic absorption spectrophotometry. RESULTS: C10B cells express highly reduced levels of Na,K-beta(1) subunit. Exogenous expression of Na,K-beta(1) increased platinum accumulation and sensitized C10B cells to oxaliplatin. The pharmacological inhibitor of Na,K-ATPase ouabain did not alter the oxaliplatin accumulation indicating that Na,K-beta(1) sensitizes cells in a Na,K-ATPase enzyme activity independent manner. These findings were also confirmed in MSV-MDCK-beta subunit cells. CONCLUSIONS: This study for the first time reveals that reduced expression of the Na,K-beta(1) protein is associated with oxaliplatin resistance in cancer cells and demonstrates a novel role for this protein in sensitizing the cells to oxaliplatin. This study suggests a potentially important role for Na,K-beta(1) in both prognosis and therapy of oxaliplatin resistant malignancies.

Capecitabine, oxaliplatin and radiotherapy: a phase IB neoadjuvant study for esophageal cancer with gene expression analysis.

PURPOSE: To determine the maximal tolerated dose of capecitabine with oxaliplatin + radiotherapy in a phase I study of localized esophageal cancer. PATIENTS AND METHODS: Oxaliplatin (85 mg/m(2)) administered on days 1, 15, and 29. Capecitabine administered twice daily 5 days weekly; dose levels (DL) were 1, 1000; 2, 1250; and 3, 1500 mg/m(2) with 50.4 Gy radiation. RESULTS: Dose-limiting toxicity was reached at DL 3. Carboxylesterase expression in day 2 tumor specimens and induction correlated with response (p

Dysregulation of purine nucleotide biosynthesis pathways modulates cisplatin cytotoxicity in Saccharomyces cerevisiae.

We found previously that inactivation of the FCY2 gene, encoding a purine-cytosine permease, or the HPT1 gene, encoding the hypoxanthine guanine phosphoribosyl transferase, enhances cisplatin resistance in yeast cells. Here, we report that in addition to fcy2Delta and hpt1Delta mutants in the salvage pathway of purine nucleotide biosynthesis, mutants in the de novo pathway that disable the feedback inhibition of AMP and GMP biosynthesis also enhanced cisplatin resistance. An activity-enhancing mutant of the ADE4 gene, which constitutively synthesizes AMP and excretes hypoxanthine, and a GMP kinase mutant (guk1), which accumulates GMP and feedback inhibits Hpt1 function, both enhanced resistance to cisplatin. In addition, overexpression of the ADE4 gene in wild-type cells, which increases de novo synthesis of purine nucleotides, also resulted in elevated cisplatin resistance. Cisplatin cytotoxicity in wild-type cells was abolished by low concentration of extracellular purines (adenine, hypoxanthine, and guanine) but not cytosine. Inhibition of cytotoxicity by exogenous adenine was accompanied by a reduction of DNA-bound cisplatin in wild-type cells. As a membrane permease, Fcy2 may mediate limited cisplatin transport because cisplatin accumulation in whole cells was slightly affected in the fcy2Delta mutant. However, the fcy2Delta mutant had a greater effect on the amount of DNA-bound cisplatin, which decreased to 50 to 60% of that in the wild-type cells. Taken together, our results indicate that dysregulation of the purine nucleotide biosynthesis pathways and the addition of exogenous purines can modulate cisplatin cytotoxicity in Saccharomyces cerevisiae.

Phase II study of weekly intravenous oxaliplatin combined with oral daily capecitabine and radiotherapy with biologic correlates in neoadjuvant treatment of rectal adenocarcinoma.

PURPOSE: To evaluate the efficacy of a combination of capecitabine, oxaliplatin, and radiotherapy (RT) in the neoadjuvant treatment of Stage II and III rectal cancers. METHODS: Capecitabine was given at 725 mg/m(2) orally twice daily Monday through Friday concurrently with RT. Oxaliplatin was given intravenously at 50 mg/m(2) once weekly five times starting the first day of RT. The radiation dose was 50.4 Gy in 28 fractions (1.8 Gy/fraction), five fractions weekly. Endorectal tumor biopsies were obtained before treatment and on the third day of treatment to explore the effects of treatment on thymidine phosphorylase, thymidylate synthase, excision repair cross-complementing rodent repair deficiency complementation group 1 (ERCC1), and apoptosis. RESULTS: A total of 25 patients were enrolled in this study; 6 patients (24%) had a complete pathologic response. T-downstaging occurred in 52% of patients, and N-downstaging occurred in 53%. Grade 3 diarrhea was the most common Grade 3-4 toxicity, occurring in 20% of patients. Only 2 patients experienced disease recurrence, with a median of 20 months of follow-up. Thymidylate synthase, thymidine phosphorylase, ERCC1, and apoptosis did not vary significantly between the pretreatment and Day 3 tumor biopsies, nor did they predict for T-downstaging or a complete pathologic response. CONCLUSION: Capecitabine at 725 mg/m(2) orally twice daily, oxaliplatin 50 mg/m(2)/wk, and RT at 50.4 Gy is an effective neoadjuvant combination for Stage II and III rectal cancer and results in a greater rate of complete pathologic responses than historically shown in fluoropyrimidine plus RT controls.

Simultaneous modeling of concentration-effect and time-course patterns in gene expression data from microarrays.

BACKGROUND: Time-course and concentration-effect experiments with multiple time-points and drug concentrations provide far more valuable information than experiments with just two design-points (treated vs. control), as commonly performed in most microarray studies. Analysis of the data from such complex experiments, however, remains a challenge. MATERIALS AND METHODS: Here we present a semi-automated method for fitting time profiles and concentration-effect patterns, simultaneously, to gene expression data. The submodels for time-course included exponential increase and decrease models with parameters, such as initial expression level, maximum effect, and rate-constant (or half-time). The submodel for concentration-effect was a 4-parameter Hill model. RESULTS: The method was applied to an Affymetrix HG-U95Av2 dataset consisting of 51 arrays. The specific study focused on the effects of two platinum drugs, cisplatin and oxaliplatin, on A2780 human ovarian carcinoma cells. Replicates were available at most time points and concentrations. Eighteen genes were selected, and after selection, time-course and concentration-effect were modeled simultaneously. CONCLUSION: Comparisons of model parameters helped to distinguish genes with different expression patterns between the two drug treatments. This overall paradigm can help in understanding the molecular mechanisms of the agents, and the timing of their actions.

A Phase I and pharmacokinetic study of selenomethionine in combination with a fixed dose of irinotecan in solid tumors.

PURPOSE: We conducted a phase I study to determine the recommended dose of selenomethionine (SLM) in combination with irinotecan that consistently results in a protective plasma selenium (Se) concentrations > 15 microM after 1 week of SLM loading. EXPERIMENTAL DESIGN: A 3-3 standard escalation design was followed. SLM was given orally twice daily (BID) for one week (loading) followed by continuous once daily (QD) dosing (maintenance). Seven dose levels of selenomethionine were investigated. Irinotecan was given intravenously at a fixed standard weekly dose, starting on the first day of maintenance SLM. RESULTS: Thirty-one patients were treated on study. Dose limiting diarrhea complicated by sepsis was noted in one of six patients at each of the dose-levels 1 and 7. Dose-levels > or = 5 (4,800 mcg/dose loading maintenance) resulted in day 8 Se concentrations >15 microM while dose-level 7 (7,200 mcg/dose loading and maintenance) resulted in day 8 Se concentrations > 20 muM. No significant variations in SN-38 or biliary index were noted between weeks 1 and 4 of treatment. Despite achieving target Se concentrations, gastrointestinal and bone marrow toxicities were common and irinotecan dose modification was prevalent. Objective responses were seen in two patients and nine patients had disease control for 6 months or longer. CONCLUSIONS: Selenomethionine can be escalated safely to 7,200 mcg BID x 1 week followed by 7,200 mcg QD in combination with a standard dose of irinotecan. No major protection against irinotecan toxicity was established; however, interesting clinical benefits were noted-supporting the investigation of this combination in future efficacy trials.

Polyamine catabolism in colorectal cancer cells following treatment with oxaliplatin, 5-fluorouracil and N1, N11 diethylnorspermine.

PURPOSE: Our previous studies showed that combined treatment of oxaliplatin and N(1), N(11) diethyl-norspermine (DENSPM) results in massive induction of spermidine/spermine N(1)-acetyltransferase (SSAT) mRNA and activity. Since oxaliplatin and 5-fluorouracil (5FU) are used clinically in treatment of colorectal cancers, this study examines the effect of adding DENSPM to oxaliplatin/5FU combination on SSAT and spermine oxidase (SMO) in HCT-116 cells. METHODS: HCT-116 cells were treated with clinically relevant concentrations of drugs for 20 h followed by 24 h in drug free medium. SSAT and SMO mRNA and protein were assayed by QRT-PCR and Westerns respectively; polyamine pools were measured by HPLC. SSAT and SMO mRNA in tumor biopsies from patients with rectal cancer receiving oxaliplatin, capecitabine and radiation were measured by QRT-PCR. RESULTS: Oxaliplatin + 5FU + DENSPM produced significantly higher levels of SSAT and SMO mRNA, protein and activity than those seen with oxaliplatin+5FU with a significant depletion of cellular spermine and spermidine pools. Oxaliplatin/DENSPM was superior to 5FU/DENSPM in SSAT induction but similar for SMO. Oxaliplatin + DENSPM revealed synergistic growth inhibition at >IC(50) concentrations and antagonism at

A functional genetic polymorphism on human carbonyl reductase 1 (CBR1 V88I) impacts on catalytic activity and NADPH binding affinity.

Human carbonyl reductase 1 (CBR1) metabolizes endogenous and xenobiotic substrates such as the fever mediator, prostaglandin E2 (PGE2), and the anticancer anthracycline drug, daunorubicin. We screened 33 CBR1 full-length cDNA samples from white and black liver donors and performed database analyses to identify genetic determinants of CBR1 activity. We pinpointed a single nucleotide polymorphism on CBR1 (CBR1 V88I) that encodes for a valine-to-isoleucine substitution for further characterization. We detected the CBR1 V88I polymorphism in DNA samples from individuals with African ancestry (p = 0.986, q = 0.014). Kinetic studies revealed that the CBR1 V88 and CBR1 I88 isoforms have different maximal velocities for daunorubicin (V(max) CBR1 V88, 181 +/- 13 versus V(max) CBR1 I88, 121 +/- 12 nmol/min . mg, p < 0.05) and PGE2 (V(max) CBR1 V88, 53 +/- 7 versus V(max) CBR1 I88, 35 +/- 4 nmol/min . mg, p < 0.01). Concomitantly, CBR1 V88 produced higher levels of the cardiotoxic metabolite daunorubicinol compared with CBR1 I88 (1.7-fold, p < 0.0001). Inhibition studies demonstrated that CBR1 V88 and CBR1 I88 are distinctively inhibited by the flavonoid, rutin (IC50 CBR1 V88, 54.0 +/- 0.4 microM versus IC50 CBR1 I88, 15.0 +/- 0.1 microM, p < 0.001). Furthermore, isothermal titration calorimetry analyses together with molecular modeling studies showed that CBR1 V88I results in CBR1 isoforms with different binding affinities for the cofactor NADPH (K(d) CBR1 V88, 6.3 +/- 0.6 microM versus K(d) CBR1 I88, 3.8 +/- 0.5 microM). These studies characterize the first functional genetic determinant of CBR1 activity toward relevant physiological and pharmacological substrates.

Celecoxib and mucosal protection: translation from an animal model to a phase I clinical trial of celecoxib, irinotecan, and 5-fluorouracil.

PURPOSE: Chemotherapy-induced diarrhea occurs secondary to mucosal inflammation and may be cyclooxygenase-2 mediated. Cyclooxygenase-2 inhibitors may ameliorate chemotherapy-induced mucosal toxicity and enhance its antitumor effect. We investigated this hypothesis in the Ward colorectal cancer rat model and in a phase I clinical study. EXPERIMENTAL DESIGN: In the Ward rat model, irinotecan was given daily x 3 or weekly x 4 with or without celecoxib. In the phase I clinical study, we planned to escalate the dose of irinotecan in the FOLFIRI regimen (irinotecan, 5-fluorouracil, and leucovorin) with a fixed dose of celecoxib. Irinotecan was escalated in four dose levels: 180, 200, 220, and 260 mg/m2. Celecoxib was administered as 400 mg, twice daily starting on day 2 of cycle 1. Pharmacokinetics of irinotecan, SN-38, and SN-38G were obtained on days 1 and 14. A standard 3+3 dose escalation scheme was used. Plasma concentrations of irinotecan, SN-38, and SN-38G were measured using high-pressure liquid chromatography. RESULTS: Celecoxib ameliorated diarrhea, weight loss, and lethality and resulted in synergistic antitumor effect in the rat model. Twelve patients with advanced cancers were enrolled and evaluable for dose-limiting toxicity (DLT). Diarrhea was the cause for discontinuation in one. Grade 2 and 3 diarrhea occurred in three and two patients, respectively. One patient had DLT at dose level 2 (grade 3 diarrhea). Two had a DLT at DL3 (G3 emesis and myocardial infarct). Celecoxib had limited influence on the pharmacokinetics of irinotecan in this data set. CONCLUSIONS: Maximum tolerated dose of irinotecan in FOLFIRI schedule with celecoxib is 200 mg/m2.

Efficacy of increasing the therapeutic index of irinotecan, plasma and tissue selenium concentrations is methylselenocysteine dose dependent.

This study was designed to understand the basis for the efficacy of methylselenocysteine (MSC) in increasing the therapeutic index of irinotecan against human tumor xenografts. Nude mice bearing human head and neck squamous cells carcinoma xenografts (FaDu and A253) were treated orally with different doses of MSC and irinotecan. Plasma, tumor and normal tissue samples were collected at different times after MSC treatments and were analyzed for selenium (Se) concentration using electrothermal atomic absorption spectrophotometry. MSC is highly effective in modulating the therapeutic index of irinotecan. Enhanced irinotecan efficacy was greater in FaDu tumors (100% CR) than in A253 tumors (60% CR), and depended on MSC dose with a minimum effective dose of 0.01 mg/dx28. The highest plasma Se concentration was achieved 1h after a single dose and 28 d after daily treatments of MSC. The ability of FaDu tumors to retain Se was significantly better than A253 tumors, and the highest Se concentration in normal tissue was achieved in the liver. Peak plasma and tissue Se concentrations were functions of the dose and duration of MSC treatment. The MSC-dependent increase in Se level in normal tissues may contribute to the protective effect against irinotecan toxicity observed in those tissues. Intratumoral total Se concentration was not found to be predictive of the combination therapy response rates. There is a critical need to develop a method to measure the active metabolite of MSC, rather than total Se.

Characterization of a clonal isolate of an oxaliplatin resistant ovarian carcinoma cell line A2780/C10.

A single cell clonal sub-line A2780/C10B that is 18-fold resistant to oxaliplatin and approximately threefold cross-resistant to cisplatin and exhibiting a metastasis associated cellular phenotype was characterized for mechanisms of resistance. The cell line exhibited a 50% reduction in the accumulation of both oxaliplatin and cisplatin relative to the parent line, while extensive decline in Pt-DNA adduct levels occurred only following oxaliplatin treatment. The basal GSH levels were fivefold higher in A2780/C10B compared to A2780 and had a fivefold elevation in gamma-GT suggesting this may be the mechanism involved in GSH elevation. The basal levels of ERCC-1, XPA and MRP-2 mRNA levels in A2780/C10B were not higher than those in A2780. The highly reduced Pt-DNA adduct formation only for oxaliplatin, but not cisplatin may be a reflection of the fact that at equimolar concentrations oxaliplatin makes fewer Pt-DNA adducts than cisplatin. The data indicate that multiple lesions occur in a single cell to produce the resistant phenotype.

Platinum drug effects on the expression of genes in the polyamine pathway: time-course and concentration-effect analysis based on Affymetrix gene expression profiling of A2780 ovarian carcinoma cells.

PURPOSE: As a follow-up to our previous findings that platinum drugs induce a key enzyme in polyamine catabolism, gene expression profiling and mathematical modeling were used to define the effects of cisplatin and oxaliplatin on the expression of polyamine metabolic pathway genes in A2780 human ovarian carcinoma cells. METHODS: Time-course and concentration-effect experiments were each carried out with cisplatin or oxaliplatin in two separate experiments and cells subjected to gene expression profiling using Affymetrix array technology. Time-course data were modeled using exponential increase and decrease models. Concentration-effect data were modeled using a four parameter Hill model. RESULTS: Gene expression profiling of human ovarian carcinoma A2780 cells after exposure to either cisplatin or oxaliplatin indicates that the expression of several genes involved in polyamine pathway is affected by the platinum drugs. Mathematical/Statistical modeling of the data from time-course and concentration-effect experiments of gene expression from nine polyamine pathway genes represented on the HGU95Av2 chip, indicates that three biosynthetic pathway genes (SAMDC, ODC1 and SRM) are down-regulated and one catabolic pathway gene (SSAT) is up-regulated. Expression changes were similar for different probesets for a given gene on the array. Studies on the induction of SSAT by platinum drugs suggested by the Affymetrix data have been previously validated from this laboratory (Hector et al. in Mol Cancer Ther 3:813-822, 2004). Here, the effects of oxaliplatin exposure on SAMDC and ODC observed by Affymetix are validated with real time QRT-PCR. CONCLUSION: The data indicate a concerted effect of platinum drugs on the polyamine metabolic pathway with down-regulation in the expression of several enzyme genes involved in biosynthesis and many-fold up-regulation in expression of SSAT, an acetylating enzyme gene that is critically involved in polyamine catabolism and export.

A Phase I study of weekly intravenous oxaliplatin in combination with oral daily capecitabine and radiation therapy in the neoadjuvant treatment of rectal adenocarcinoma.

PURPOSE: We conducted a Phase I study to determine the maximum tolerated dose (MTD) of neoadjuvant capecitabine, oxaliplatin, and radiation therapy (RT) in Stage II to III rectal adenocarcinoma. METHODS AND MATERIALS: Capecitabine was given orally twice daily Monday through Friday concurrently with RT. Oxaliplatin was given i.v. once weekly x 5 (for 5 weeks) starting the first day of RT. RT was given daily except on weekends and holidays at 1.8 Gy per fraction x 28. Escalation for capecitabine or oxaliplatin was to occur in cohorts of three patients until the maximum tolerated dose (MTD) was defined. Endorectal tumor biopsy samples were obtained before and on Day 3 of treatment to explore the effects of treatment on thymidine phosphorylase, thymidylate synthase, dihydropyrimidine dehydrogenase, DNA repair, and apoptosis. RESULTS: Twelve patients were enrolled on this study. Two of 6 patients at dose level (DL) 1 (capecitabine 825 mg/m2 orally (p.o.) given twice daily (b.i.d.); oxaliplatin 50 mg/m2/week) had a dose-limiting diarrhea. One of 6 patients at DL (-)1 (capecitabine 725 mg/m2 p.o., b.i.d.; oxaliplatin 50 mg/m2/week) experienced-dose-limiting diarrhea. Three of 11 patients who underwent resection had a complete pathologic response. No remarkable variations in rectal tumor biologic endpoints were noted on Day 3 of treatment in comparison to baseline. However, a higher apotosis index was observed at baseline and on Day 3 in complete pathologic responders (no statistical analysis performed). CONCLUSIONS: Capecitabine 725 mg/m2 p.o., twice daily in combination with oxaliplatin 50 mg/m2/week and RT 50.4 Gy in 28 fractions is the recommended dose for future studies.

A phase I and pharmacokinetic study of fixed-dose selenomethionine and irinotecan in solid tumors.

PURPOSE: We conducted a phase I study to determine the maximum tolerated dose (MTD) of irinotecan with fixed, nontoxic high dose of selenomethionine. EXPERIMENTAL DESIGN: Selenomethionine was given orally as a single daily dose containing 2,200 mug of elemental selenium (Se) starting 1 week before the first dose of irinotecan. Irinotecan was given i.v. once weekly x 4 every 6 weeks (one cycle). The starting dose of irinotecan was 125 mg/m(2)/wk. Escalation occurred in cohorts of three patients until the MTD was defined. Pharmacokinetic studies were done for selenium and irinotecan and its metabolites. RESULTS: Three of four evaluable patients at dose level 2 of irinotecan (160 mg/m(2)/wk) had a dose-limiting diarrhea. None of the six evaluable patients at dose level 1 (125 mg/m(2)/wk irinotecan) had a dose-limiting toxicity. One patient with history of irinotecan-refractory colon cancer achieved a partial response. The long half-life of selenium resulted in a prolonged accumulation towards steady-state concentrations. No significant changes in the pharmacokinetics of CPT-11, SN-38, or SN-38G were identified; however, the coadministration of selenomethionine significantly reduced the irinotecan biliary index, which has been associated with gastrointestinal toxicity. CONCLUSIONS: Selenomethionine at 2,200 mug/d did not allow the safe escalation of irinotecan beyond the previously defined MTD of 125 mg/m(2). None of the patients receiving 125 mg/m(2) of irinotecan had grade >2 diarrhea. Unexpected responses and disease stabilizations were noted in a highly refractory population. Further escalation of selenomethionine is recommended in future trials to achieve defined protective serum concentrations of selenium.

Sequential administration of irinotecan and cytarabine in the treatment of relapsed and refractory acute myeloid leukemia.

PURPOSE: Based on reported synergy of the topoisomerase-I (topo-I) inhibitor irinotecan with antimetabolites, irinotecan and cytarabine (Ara-C) were administered sequentially to patients with acute myeloid leukemia (AML) refractory to or relapsed following high-dose Ara-C and anthracycline therapy. Pharmacokinetic and pharmacodynamic studies were performed with the first irinotecan dose. EXPERIMENTAL DESIGN: In vitro synergy of irinotecan followed by Ara-C was confirmed in a human AML cell line as a basis for the clinical trial. Irinotecan was administered daily for 5 days, with Ara-C 1 g/m2 12 h after each irinotecan dose. Irinotecan was initiated at 5 mg/m2, and the dose was escalated by 5 mg/m2 increments in cohorts of three patients and in individual patients. Pre-treatment samples were studied for topo-I activity and serial samples after the first irinotecan dose were analyzed for pharmacokinetics and for pharmacodynamic effects, including DNA damage and DNA synthesis rate. RESULTS: The irinotecan dose reached 15 mg/m2 in three-patient cohorts without reaching the maximum tolerated dose, and reached 30 mg/m2 in individual patients. The AUC and Cmax of both irinotecan and its active metabolite SN38 increased linearly in proportion to dose, and the mean half-lives of irinotecan conversion to SN38 and SN38 elimination were 6.2 h (CV 171%) and 7.2 h (CV 48%). Irinotecan rapidly induced DNA damage, and DNA synthesis inhibition varied among patients and treatment cycles. All courses resulted in rapid cytoreduction, and two patients achieved complete remission. Topo-I activity did not predict response. CONCLUSION: Irinotecan can be safely administered with Ara-C. This combination is active in refractory AML and warrants further study.