xr5944 and Neoplasms

This review is dedicated to Professor William A. Denny's discovery of XR5944 (also known as MLN944). XR5944 is a DNA-targeted agent with exceptionally potent antitumor activity and a novel DNA binding mode, bis-intercalation and major groove binding, as well as a novel mechanism of action, transcription inhibition. This novel anticancer compound represents a remarkable accomplishment resulting from two decades of drug discovery by Professor Denny and coworkers. Here, we review our work on the structural study of the DNA binding mode of XR5944 and mechanistic study of XR5944 action.

Topics: Animals; Antineoplastic Agents; DNA; Humans; Intercalating Agents; Neoplasms; Phenazines

The bis-phenazine XR5944.14 is a novel cytotoxic agent which intercalates into DNA and inhibits transcription. The objectives of this study were to determine the dose-limiting toxicity (DLT), the maximum tolerated dose (MTD) and to describe the pharmacokinetics (PKs) of XR5944.14 when given at doses ranging from 3.6 to 36 mg m(-2) every 3 weeks to patients with advanced tumours. Twenty-seven patients were treated with a total of 77 cycles. Dose-limiting toxicities occurred at doses > or =24 mg m(-2). Oral mucositis was the most common DLT. Two patients developed acute renal failure possibly related to the study drug. Other less-severe toxicities were diarrhoea, nausea, vomiting and fatigue. Haematological toxicity was mild. One patient showed an objective partial response. Pharmacokinetic analysis was performed during the first cycle of treatment and plasma was assayed for XR5944.14 using a validated liquid chromatography tandem mass spectrometry. The systemic exposure of XR5944.14 increased more than proportionally with increasing dose, with inter-patient variability increasing from dose level 24 mg m(-2) onwards. The lack of correlation between toxicity and PK values makes it difficult to recommend a dose for further study in phase 2 trials. More work is needed to explain the inter- and intra-individual variation in PKs and pharmacodynamics.

Topics: Adult; Aged; Area Under Curve; Female; Humans; Infusions, Intravenous; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Phenazines

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.

Topics: Adult; Aged; Aged, 80 and over; Antigens, Neoplasm; ATP Binding Cassette Transporter, Subfamily B, Member 1; DNA Topoisomerases, Type I; DNA Topoisomerases, Type II; DNA-Binding Proteins; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Female; Gene Expression Profiling; Humans; Male; Middle Aged; Multidrug Resistance-Associated Proteins; Neoplasms; Phenazines; Tumor Cells, Cultured; Vault Ribonucleoprotein Particles