Ames, Matthew M.

Abstract One of the key challenges in anticancer therapy is the toxicity and poor bioavailability of the anticancer drugs. Nanotechnology can play a pivotal role by delivering drugs in a targeted fashion to the malignant cells that will reduce the systemic toxicity of the anticancer drug. In this report, we show a stepwise development of a nanoparticle-based targeted delivery system for in vitro and in vivo therapeutic application in pancreatic cancer. In the first part of the study, we have shown the fabrication and characterization of the delivery system containing gold nanoparticle as a delivery vehicle, cetuximab as a targeting agent, and gemcitabine as an anticancer drug for in vitro application. Nanoconjugate was first characterized physico-chemically. In vitro targeting efficacy, tested against three pancreatic cancer cell lines (PANC-1, AsPC-1, and MIA Paca2) with variable epidermal growth factor receptor (EGFR) expression, showed that gold uptake correlated with EGFR expression. In the second part, we showed the in vivo therapeutic efficacy of the targeted delivery system. Administration of this targeted delivery system resulted in significant inhibition of pancreatic tumor cell proliferation in vitro and orthotopic pancreatic tumor growth in vivo. Tumor progression was monitored noninvasively by measuring bioluminescence of the implanted tumor cells. Pharmacokinetic experiments along with the quantitation of gold both in vitro and in vivo further confirmed that the inhibition of tumor growth was due to targeted delivery. This strategy could be used as a generalized approach for the treatment of a variety of cancers characterized by overexpression of EGFR. [Cancer Res 2008;68(6):1970–8]

Abstract Folylpolyglutamate synthase (FPGS) catalyzes the polyglutamation of folic acid, methotrexate, and pemetrexed to produce highly active metabolites. To characterize genetic variation in the FPGS gene, FPGS, have resequenced the gene in four different ethnic populations. Thirty-four single nucleotide polymorphisms were identified including five nonsynonymous coding single nucleotide polymorphisms that altered the FPGS protein sequence: F13L and V22I polymorphisms in the mitochondrial isoform of FPGS, and R466/424C, A489/447V, and S499/457F polymorphisms, which exist in both the mitochondrial and cytosolic isoforms. When expressed in AuxB1 cells, the A447V cytosolic variant was functionally similar to the wild-type cytosolic (WT Cyt) allozyme, whereas the R424C and S457F cytosolic variants were reduced by ∼2-fold in protein expression compared with WT Cyt (P < 0.01). The intrinsic clearance of glutamate was reduced by 12.3-fold (R424C, P < 0.01) and 6.2-fold (S457F, P < 0.01), whereas the intrinsic clearance of methotrexate was reduced by 4.2-fold (R424C, P < 0.05) and 5.4-fold (S457F, P < 0.05) in these two cytosolic variants when compared with the WT Cyt isoform. Additionally, the in vitro enzyme velocity at saturating pemetrexed concentrations was reduced by 1.6-fold (R424C, P < 0.05) and 2.6-fold (S457F, P < 0.01) compared with WT Cyt. AuxB1 cells harboring these same cytosolic variant allozymes displayed significant increases in the EC50 for folic acid and in the IC50 values for both methotrexate and pemetrexed relative to the WT Cyt form of FPGS. These observations suggest that genetic variations in FPGS may alter the efficacy of antifolate therapy in cancer patients. [Cancer Res 2007;67(18):8772–82]

PurposeWe report results of a phase I trial and pharmacokinetic study of pemetrexed (LY231514) in children and adolescents with refractory solid tumors. Pemetrexed is a novel antifolate that inhibits multiple enzymes necessary for the biosynthesis of thymidine and purine nucleotides. The purpose of this study was to determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLTs), and pharmacokinetic properties of pemetrexed in children.Patients and MethodsPemetrexed was administered as a 10-minute intravenous infusion every 21 days. Patients received vitamin B12and folic acid supplementation as well as dexamethasone prophylaxis. Cohorts of three to six children were enrolled at dose levels of 400, 520, 670, 870, 1,130, 1,470, 1,910, and 2,480 mg/m2. Pharmacokinetic studies were performed during the first course of treatment.ResultsThirty-three patients (31 assessable) with a median age of 12 years were enrolled. DLT occurred in one of six patients at 1,470 mg/m2and two of four patients at 2,480 mg/m2. The MTD was 1,910 mg/m2. The primary DLTs were neutropenia and rash. No objective antitumor responses were seen. Mean plasma clearance, half-life, and steady-state volume of distribution values were 2.3 L/h/m2, 2.5 hours, and 5.4 L/m2, respectively.ConclusionPemetrexed is well-tolerated in children with refractory solid tumors at doses similar to the MTD in adults. The recommended dose for phase II studies is 1,910 mg/m2administered every 21 days with dexamethasone, folic acid, and vitamin B12supplementation.

Abstract Purpose: To determine the recommended phase 2 dose, dose-limiting toxicities (DLT), pharmacokinetic profile, and pharmacodynamics of the heat shock protein (Hsp) 90 inhibitor, 17-allylaminogeldanamycin (17-AAG). Experimental Design: 17-AAG was administered as a 60-min infusion, on days 1, 4, 8, and 11 of a 21-day cycle at dose levels of 150, 200, 270, and 360 mg/m2/dose. Pharmacokinetic studies and evaluations for Hsp72 and Akt levels in peripheral blood mononuclear cells were done during the first course of therapy. Results: Seventeen patients (7 males), median 7 years of age (range, 1-19 years), were enrolled using a standard dose escalation scheme. No DLTs were observed. Although there were no objective responses, three patients remain on therapy at 6+, 7+, and 9+ months with stable disease. One patient with hepatoblastoma had a reduction in α-fetoprotein and stable disease over three cycles. At 270 mg/m2/dose, the Cmax and areas under the plasma concentration-time curves of 17-AAG were 5,303 ± 1,591 ng/mL and 13,656 ± 4,757 ng/mL h, respectively, similar to the exposure in adults. The mean terminal half-life for 17-AAG was 3.24 ± 0.80 h. Induction of Hsp72, a surrogate marker for inhibition of Hsp90, was detected at the 270 mg/m2 dose level. Conclusions: Drug exposures consistent with those required for anticancer activity in preclinical models were achieved without DLT. Evidence for drug-induced modulation of Hsp90 systemically was also detected. The recommended phase II dose of 17-AAG is 360 mg/m2/d. Non-DMSO–containing formulations may improve acceptance of this drug by children and their families.

Abstract Purpose: To determine the maximum tolerated dose (MTD), dose-limiting toxicity, and pharmacokinetics of 17-allylamino-demethoxy-geldanamycin (17-AAG) administered on days 1, 4, 8, and 11 every 21 days and to examine the effect of 17-AAG on the levels of chaperone and client proteins. Experimental Design: A phase I dose escalating trial in patients with advanced solid tumors was done. Toxicity and tumor responses were evaluated by standard criteria. Pharmacokinetics were done and level of target proteins was measured at various points during cycle one. Results: Thirteen patients were enrolled in the study. MTD was defined as 220 mg/m2. Dose-limiting toxicities were as follows: dehydration, diarrhea, hyperglycemia, and liver toxicity. At the MTD, the mean clearance of 17-AAG was 18.7 L/h/m2. There was a significant decrease in integrin-linked kinase at 6 hours after infusion on day 1 but not at 25 hours in peripheral blood mononuclear cells. Treatment with 17-AAG on day 1 significantly increased pretreatment levels of heat shock protein (HSP) 70 on day 4, which is consistent with the induction of a stress response. In vitro induction of a stress response and up-regulation of HSP70 resulted in an increased resistance to HSP90-targeted therapy in A549 cells. Conclusions: The MTD of 17-AAG on a twice-weekly schedule was 220 mg/m2. Treatment at this dose level resulted in significant changes of target proteins and also resulted in a prolonged increase in HSP70. This raises the possibility that HSP70 induction as part of the stress response may contribute to resistance to 17-AAG.

Epidemiologic studies strongly associate eosinophilia-myalgia syndrome (EMS) with ingestion of tryptophan containing a contaminant ("peak E"). Prior reports have suggested that peak E is the di-tryptophan Nα-animal of acetaldehyde. Spectral and chemical studies now demonstrate that peak E is 1,1′-ethylidenebis[tryptophan]. This novel amino acid may be the etiological agent responsible for EMS, or it may be a marker of a still unidentified causal agent.

PurposeTo determine the maximal tolerated dosage (MTD) of oral fenretinide given as intact capsules for 7 days, repeated every 21 days, in children with high-risk solid tumors.MethodsChildren 21 years of age or younger received daily doses from 350 mg/m2to 3,300 mg/m2(divided into two or three doses), with pharmacokinetics during course one. The MTD was defined as zero to one of six patients with dose-limiting toxicity (DLT), with at least two of three or two of six DLT at next higher dose.ResultsFifty-four patients, age 2 years to 20 years (median, 9 years), were treated: neuroblastoma (n = 39), Ewing sarcoma (n = 5), and other (n = 10). Prior therapy included autologous stem cell transplantation (n = 42), 13-cis-RA (n = 35), and 9-cis-RA (n = 1). One of four patients at 1,050 mg/m2with prior liver transplant had grade 3 ALT/abdominal pain/nausea/dehydration and grade 4 AST/emesis. At 1,860 mg/m2, one of seven patients had grade 3 hypoalbuminemia/hypophosphatemia. At 2,475 mg/m2, one of eight patients had grade 3 alkaline phosphatase; three of five patients had DLT at 3,300 mg/m2: grade 3 AST/ALT (n = 1), grade 4 bilirubin/grade 3 AST/ALT (n = 1), pseudotumor cerebri (n = 1). Pseudotumor cerebri also occurred at 600 mg/m2and 800 mg/m2. There was one complete response and 13 patients with stable disease (SD) for 8 or more courses in 30 assessable neuroblastoma patients. SD for 8 or more courses was seen in one of five Ewing sarcoma patients and one melanoma patient. Mean N-4-hydroxyphenyl retinamide plasma level (day 7, steady-state concentration) was 9.9 μmol/L at MTD.ConclusionThe pediatric MTD of oral capsular fenretinide was 2,475 mg/m2per day, which achieved levels active against neuroblastoma in vitro with minimal toxicity. Response data support a phase II trial in neuroblastoma.

Abstract Purpose: Vinorelbine (Navelbine) is an orally absorbable Vinca with broad antitumor activity. It differs from other Vinca in that it is structurally modified on the catharanthine nucleus and has differential actions on tubulin that render it less neurotoxic than other compounds in this class. We conducted a phase I study of vinorelbine given the activity of Vinca alkaloids in many pediatric tumors. Experimental Design: We evaluated the safety and pharmacokinetics of oral and i.v. vinorelbine administered weekly × 6 in children (age, 2-17 years) with different tumors. Patients with disease involvement in the bone marrow were eligible but were stratified and dose-escalated separately. Oral vinorelbine (week 1) was administered as liquid-filled gelatin capsules at thrice the i.v. dose. Intravenous vinorelbine doses of 24 to 37.5 mg/m2 were administered on weeks 2 to 6. Results: The dose-limiting toxicity in patients without marrow involvement was reversible neutropenia. Common nonhematologic toxicities included ≤ grade 2 nausea/vomiting and increased hepatic transaminases. A higher mean i.v. ClTB was observed (1.75 ± 1.0 L/h/kg) compared with adult reports, with a mean t1/2B of 16.5 ± 9.7 hours. Mean oral bioavailability was 28.5 ± 22.5%. The apparent oral clearance (12.1 ± 13.0 L/h/kg) and volume of distribution (69.4 ± 30.6 L/kg) were substantially higher than in adults given similar oral doses. Conclusions: The maximum tolerated dose in children without bone marrow involvement was 30 mg/m2, similar to that reported in adults, with myelosuppression being the dose-limiting toxicity. Higher plasma clearance resulted in lower area under the plasma concentration-time curves at a given dose compared with that reported in adults.

Abstract Purpose: Gemcitabine is a nucleoside analogue with activity against solid tumors. Gemcitabine metabolic inactivation is catalyzed by cytidine deaminase (CDA) or, after phosphorylation, by deoxycytidylate deaminase (DCTD). We set out to study the pharmacogenomics of CDA and DCTD. Experimental Design: The genes encoding CDA and DCTD were resequenced using DNA from 60 African American and 60 Caucasian American subjects. Expression constructs were created for nonsynonymous coding single nucleotide polymorphisms (cSNP) and reporter gene constructs were created for 5′-flanking region polymorphisms. Functional genomic studies were then conducted after the transfection of mammalian cells. Results: CDA resequencing revealed 17 polymorphisms, including one common nonsynonymous cSNP, 79 A>C (Lys27Gln). Recombinant Gln27 CDA had 66 ± 5.1% (mean ± SE) of the wild-type (WT) activity for gemcitabine but without a significant decrease in level of immunoreactive protein. The apparent Km (397 ± 40 μmol/L) for the Gln27 allozyme was significantly higher than that for the WT (289 ± 20 μmol/L; P < 0.025). CDA 5′-flanking region reporter gene studies showed significant differences among 5′-flanking region haplotypes in their ability to drive transcription. There were 29 SNPs in DCTD, including one nonsynonymous cSNP, 172 A>G (Asn58Asp), in Caucasian American DNA. Recombinant Asp58 DCTD had 11 ± 1.4% of WT activity for gemcitabine monophosphate with a significantly elevated level of immunoreactive protein. No DCTD polymorphisms were observed in the initial 500 bp of the 5′-flanking region. Conclusions: These results suggest that pharmacogenomic variation in the deamination of gemcitabine and its monophosphate might contribute to variation in therapeutic response to this antineoplastic agent.