Myoblasts transferred once a month for six months failed to improve strength in patients with Duchenne's muscular dystrophy. The value of exon-specific peptide antibodies in the interpretation of myoblast-transfer results was demonstrated in a patient with Duchenne's muscular dystrophy who had a high percentage of donor-derived dystrophin. Specific variables affecting the efficiency of myoblast transfer need to be identified in order to improve upon this technique.

The metabolism of (177)Lu-AMBA (AMBA = DO3A-CH(2)CO-G-(4-aminobenzoyl)-QWAVGHLM-NH(2)), a radiotherapeutic compound in clinical development that binds to GRP and NMB receptors, was studied in vitro (mouse, rat and human plasma, mouse kidney homogenate) and in vivo (by analysis of mouse and rat plasma and urine following IV injection of (177)Lu-AMBA). The primary metabolites were Lu-DO3A-CH(2)CO-G-Abz4-R, where R = -Q-OH (A), -QW-OH (B), and -QWAVGH-OH (C). Minor amounts of (D) where R = -QWAVGHLM-OH and (E) -QWAVGHL-OH were also observed. Clearance of (177)Lu-AMBA and of radioactivity from mouse and rat blood was rapid in vivo. In mouse and rat urine, only metabolites Lu-A and Lu-B were found-no parent drug was excreted. Unmetalated ligands and (nat)Lu and (177)Lu complexes for Lu-AMBA metabolites A-E were synthesized, characterized by HPLC and MS, and used to perform in vitro competition and direct binding studies on GRP receptor-positive PC-3 (human prostate) cancer cells. Biodistribution studies with (177)Lu-labeled metabolites A-E were performed in PC-3 tumor-bearing mice and the results compared with intact (177)Lu-AMBA. IC(50) values for unmetalated metabolite ligands A-E were >400 nM in PC-3 cells in competition binding studies against (177)Lu-AMBA. No direct binding to PC-3 cells was observed with (177)Lu-labeled A-C, confirming IC(50) results. (177)Lu-labeled metabolites A-E showed no uptake in GRP-receptor positive tumor or pancreas in PC-3 tumor bearing mice. All metabolites were rapidly excreted via the renal route (approximately 78-87%) within 1 h. These results demonstrate that the tumor uptake observed with (177)Lu-AMBA is due to parent drug and not due to any of its identified metabolites.

( 177 Lu-AMBA) is a radiolabeled bombesin derivative that is bound and internalized by cells expressing the G-proteincoupled gastrin-releasing peptide receptor (GRP-R) and is currently in phase I clinical trials. In previous radiotherapy studies with PC-3 xenografted mice, 177 Lu-AMBA treatment significantly increased survival and reduced tumor growth rates. The PC-3 tumor cell line has an elevated expression of GRP-Rs (2.5 · 10 5 /cell), whereas LNCaP-a prostate cancer metastatic cell line representing the early androgen-sensitive stage of prostate cancer-and DU145-an androgen-insensitive metastatic lineexpress lower receptor numbers (5.9 · 10 3 and 1.2 · 10 4 /cell, respectively). Because of tumor heterogeneity, the high number of receptors in the PC-3 line may not represent the clinical situation, and little definitive work on the GRP-R status of primary prostate tumors and metastases exists. We sought to evaluate the tumor binding and imaging potential of 177 Lu-AMBA in low GRP-R models of prostate cancer and determine how reduced expression affects 177 Lu-AMBA radiotherapy efficacy. Methods: The LNCaP and DU145 cell lines were used to determine the binding (K d ), retention, and efflux of 177 Lu-AMBA. Biodistribution radiotherapy, imaging, and autoradiography studies were performed in LNCaP, DU145, or PC-3 tumor-bearing male nude mice. Immunohistochemistry was used to determine the proliferative state in LNCaP and DU145 models and the vascular phenotype of LNCaP radiotherapy tumors. Results: 177 Lu-AMBA binds to GRP-R in these cell lines with high affinity (K d of LNCaP, 0.65 6 0.2 nM; K d of DU145, 0.53 6 0.1 nM). The uptake of 177 Lu-AMBA is at least 10-fold less in LNCaP and DU145 cell lines than it is in the PC-3 cell line. Autoradiography identifies activity concentrated in areas of viable tumor tissue, and g-images of 177 Lu-AMBA identify tumors in vivo. Despite having lower uptake, 177 Lu-AMBA demonstrated radiotherapeutic efficacy and decreased proliferation in the LNCaP and DU145 xenografts; in the LNCaP model, 177 Lu-AMBA normalized the phenotype of microvasculature, reducing tumoral blood pooling. Conclusion: 177 Lu-AMBA is a single radiolabeled agent that combines targeted radiotherapy after imaging dosimetry with the potential for single-agent or multimodality therapy for prostate cancer. Prost ate cancer is the leading cause of cancer death in men, with an estimated 186,320 cases diagnosed and more than 28,000 deaths in the United States during 2008 (1).The design of a therapeutic course for the patient with prostate cancer can be particularly difficult because of the heterogeneity of the disease. The phenotypic characteristics of metastatic prostate cancer can show a broad spectrum, even within the same patient at the same time (2). The development of a single radiolabeled agent that could function as both a radiotherapeutic and an imaging agent for dosimetry, with the potential as an adjunct to traditional chemotherapy, could ameliorate these difficulties and result in better management of ...

Cytotoxicities of tocopherols (alpha-T, gamma-T, delta-t), their para (alpha-TQ, gamma-TQ, delta-TQ)- and ortho (Tocored)-quinone oxidation products, the synthetic quinone analog of gamma-TQ containing a methyl group substituted for the phytyl side-chain (TMCQ) and the synthetic quinone analog of Tocored containing a methyl group substituted for the phytyl side-chain (PR) were measured in acute lymphoblastic leukemia cell lines that are drug-sensitive (CEM) and multidrug-resistant (CEM/VLB100). Among tocopherols, only delta-T exhibited cytotoxicity. Among para quinones, alpha-TQ showed no cytotoxicity, while gamma-TQ and delta-TQ were highly cytotoxic in both CEM and CEM/VLB100 cell lines (LD50 < 10 muM). delta-TQ and gamma-TQ were more cytotoxic than the widely studied chemotherapeutic agent doxorubicin, which also showed selective cytotoxicity to CEM cells. The orthoquinone Tocored was less cytotoxic than doxorubicin in drug-sensitive cells but more cytotoxic than doxorubicin in multidrug-resistant cells. Cytotoxicity was not a function of the phytyl side-chain since both TMCQ and PR were cytotoxic in leukemia cells. Cytotoxic para and ortho quinones were electrophiles that formed adducts with nucleophilic thiol groups in glutathione and 2-mercaptoethanol. Cytotoxicity was enhanced when the glutathione pool was depleted by preincubation with buthionine-[S,R]-sulfoximine, but cytotoxicity was diminished by the addition of N-acetylcysteine to cultures. alpha-T also diminished the cytotoxicity of para- and orthoquinones. Buthionine-[S,R]-sulfoximine did not block the inhibitory effect of either N-acetylcysteine or alpha-T, showing that these agents did not act solely by maintaining the glutathione pool as an essential antioxidant system. In conclusion, tocopherylquinones represent a new class of alkylating electrophilic quinones that function as highly cytotoxic agents and escape multidrug resistance in acute lymphoblastic leukemia cell lines.

Carcinogenesis is a multistep process in which many alterations in both genetic and epigenetic controls lead to a growth advantage for neoplastic cells. Hypermethylation has been established as the basis of genomic imprinting, but recent studies have also shown that alterations in genomic methylation patterns may contribute to tumorigenesis. The chemical 5-aza-2'-deoxycytidine (5-aza-dC) has been used both in vitro and in vivo to inhibit DNA methylation. In this study, we investigated the chemopreventive efficacy of 5-aza-dC in a well-established primary mouse lung tumor model. Five-week-old male (C3H/HeJ x A/J) F1 hybrid mice were treated for 24 consecutive weeks with 5-aza-dC, three times per week i.p. Lung tumors were induced with two consecutive weekly doses of 4-(methyl-nitrosamino)-1-(3-pyridyl)-1-butanone starting 1 week after initial treatment with 5-aza-dC. We demonstrated that 5-aza-dC exhibits a chemopreventive effect in this primary mouse lung tumor model which, like human lung adenocarcinomas, harbors an activating K-ras mutation. Treatment with 5-aza-dC resulted in a 23% reduction in tumor incidence, as well as a 42% reduction in tumor multiplicity. This work supports further investigation of methylation inhibitors likes 5-aza-dC for early intervention, prevention and treatment of lung cancer.