title: The ex vivo characterization of XR5944 (MLN944) against a panel of human clinical tumor samples.
abstract: XR5944 (MLN944) is a novel DNA targeting agent with potent antitumor activity, both in vitro and in vivo, against several murine and human tumor models. We have used an ATP-tumor chemosensitivity assay to assess the ex vivo sensitivity of a variety of solid tumors (n = 90) and a CCRF-CEM leukemia cell line selected with XR5944. Differences in gene expression between the parental CCRF-CEM and the resistant subline were investigated by quantitative reverse transcription-PCR. Immunohistochemistry for topoisomerases I and IIalpha and multidrug resistance (MDR1) protein was done on those tumors for which tissue was available (n = 32). The CCRF-CEM XR5944 line showed increased mRNA levels of MDR1, major vault protein, and MDR-associated protein 1 compared with the parental line, whereas the expression of topoisomerases I, IIalpha, and IIbeta was essentially unchanged, suggesting that XR5944 is susceptible to MDR mechanisms. The median IC90 and IC50 values for XR5944 in tumor-derived cells were 68 and 26 nmol/L, respectively, 6-fold greater than in resistant cell lines. XR5944 was 40- to 300-fold more potent than the other cytotoxics tested, such as doxorubicin, topotecan, and paclitaxel. Breast and gynecologic malignancies were most sensitive to XR5944, whereas gastrointestinal tumors showed greater resistance. A positive correlation (r = 0.68; P < 0.0001) was found between the IC50 values of XR5944 and P-glycoprotein/MDR1 staining but not with either topoisomerase I or IIalpha immunohistochemistry index. These data support the rapid introduction of XR5944 to clinical trials and suggest that it may be effective against a broad spectrum of tumor types, especially ovarian and breast cancer.
authors.affiliation: Translational Oncology Research Centre, Department of Histopathology, Queen Alexandra Hospital, Portsmouth, United Kingdom.
authors.forename: Federica
authors.initials: F
authors.lastname: Di Nicolantonio
authors.forename: Louise A
authors.initials: LA
authors.lastname: Knight
authors.forename: Pauline A
authors.initials: PA
authors.lastname: Whitehouse
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Mercer
authors.forename: Sanjay
authors.initials: S
authors.lastname: Sharma
authors.forename: Peter A
authors.initials: PA
authors.lastname: Charlton
authors.forename: David
authors.initials: D
authors.lastname: Norris
authors.forename: Ian A
authors.initials: IA
authors.lastname: Cree
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000235:genetics / Q000378:metabolism; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D010619:Phenazines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D020394:Vault Ribonucleoprotein Particles / Q000235:genetics / Q000378:metabolism; D000099187:Major Vault Protein
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000951:Antigens, Neoplasm; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D004268:DNA-Binding Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010619:Phenazines; D020394:Vault Ribonucleoprotein Particles; D000099187:Major Vault Protein; C434883:XR5944