Phase I trial of the anthrapyrazole CI-941: prospective evaluation of a pharmacokinetically guided dose-escalation

The development of phase I cancer trial methodologies: the use of pharmacokinetic and pharmacodynamic end points sets the scene for phase 0 cancer clinical trials

Although the concept of a phase 0 trial is a relatively new one, there has been a slowly increasing trend toward basing early clinical trial designs on pharmacokinetic and pharmacodynamic end points that has been developing over many years. This article will review the early cancer trial methodologies and the various techniques that have been used to refine them. Several illustrative examples will be presented showing their relevance to trial designs using pharmacodynamic end points and targeted agents. Some criteria for characterizing suitable phase 0 end points are suggested. Four trial designs that are essentially developed for cytotoxic agents using the maximal tolerated dose as an end point are described. Although these trials were not designed with the use of more sophisticated pharmacodynamic end points (such as the measurement of the effect of a targeted agent on its target), they have been developed to optimize the speed with which a dose needed to achieve a particular effect can be determined and are, to this extent, relevant to the design of studies with pharmacodynamic end points.

Phase I study of the combination of losoxantrone and cyclophosphamide in patients with refractory solid tumours

Losoxantrone is a DNA intercalator that was developed with the potential to replace anthracyclines. The recommended single agent dose of losoxantrone is 50 mg m(-2) every 3 weeks. We conducted a phase I study of losoxantrone and a fixed dose of cyclophosphamide on a q3 weekly schedule. Forty-nine patients were enrolled, of which 46 were evaluable for toxicity. The dose-limiting toxicity was neutropenia at the maximum tolerable losoxantrone dose of 45 mg m(-2). With granulocyte colony-stimulating factor support, significant further dose escalation of losoxantrone was achieved. Cardiotoxicity was seen with cumulative dosing. Pharmacokinetics of losoxantrone revealed linear kinetics and triphasic clearance, with significant interpatient variability. No objective responses were seen in this study. Neutropenia was dose-limiting in this combination with or without granulocyte colony-stimulating factor support. The recommended dose for further testing is cyclophosphamide 500 mg m(-2) followed by losoxantrone 95 mg m(-2) with granulocyte colony-stimulating factor support.

Evaluation of rodent-only toxicology for early clinical trials with novel cancer therapeutics

Preclinical toxicology studies are performed prior to phase I trials with novel cancer therapeutics to identify a safe clinical starting dose and potential human toxicities. The primary aim of this study was to evaluate the ability of rodent-only toxicology studies to identify a safe phase I trial starting dose. In addition, the ability of murine studies to predict the quantitative and qualitative human toxicology of cancer therapeutics was studied. Data for 25 cancer drugs were collated for which the preclinical and clinical routes and schedules of administration were either the same (22/25), or closely matched. The maximum tolerated dose/dose lethal to 10% of mice (MTD/LD10) was identified for 24 drugs, and in patients the maximum administered dose (MAD) was associated with dose-limiting toxicity (DLT) in initial clinical trials with 20 compounds. In addition, for 13 agents, the toxicity of the drug at one-tenth the mouse MTD/LD10 was also investigated in rats, following repeated administration (20 doses). A phase I trial starting dose of one-tenth the mouse MTD/LD10 (mg m(-2)) was, or would have been, safe for all 25 compounds. With the exception of nausea and vomiting, which cannot be assessed in rodents, other common DLTs were accurately predicted by the murine studies (i.e. 7/7 haematological and 3/3 neurological DLTs). For two of the 13 drugs studied in rats, repeated administration of one-tenth the mouse MTD/LD10 was toxic, leading to a reduction in the phase I trial starting dose; however, one-tenth the mouse MTD/LD10 was subsequently tolerated in patients. For the 20 drugs where clinical DLT was reached, the median ratio of the human MAD to the mouse MTD/LD10 was 2.6 (range 0.2-16) and the median ratio of the clinical starting dose to the MAD was 35 (range 2.3-160). In contrast, in 13 subsequent phase I trials with 11 of the initial 25 drugs, the median ratio of the clinical starting dose to the MAD was 2.8 (range 1.6-56), emphasizing the value of early clinical data in rapidly defining the dose range for therapeutic studies. For all 25 drugs studied, rodent-only toxicology provided a safe and rapid means of identifying the phase I trial starting dose and predicting commonly encountered DLTs. This study has shown that the routine use of a non-rodent species in preclinical toxicology studies prior to initial clinical trials with cancer therapeutics is not necessary.

Comparison of the chronic toxicity of piroxantrone, losoxantrone and doxorubicin in spontaneously hypertensive rats

Comparisons were made of the toxic effects produced in the heart, kidney and small intestine of spontaneously hypertensive rats (SHR) by the administration of 12 consecutive weekly doses of doxorubicin (1 mg/kg), and high, intermediate and low doses of piroxantrone (3, 1.5 and 0.75 mg/kg) and losoxantrone (1, 0.5 and 0.25 mg/kg). Animals receiving saline were used as controls. The toxicities of the three drugs were evaluated by clinical chemistry and hematological determinations, light microscopy and transmission electron microscopy. The severity of the histologic alterations in heart, kidney and small intestine was assessed semiquantitatively. Biochemical and molecular modeling studies were made to evaluate the formation of complexes of Fe(III) with piroxantrone and losoxantrone. The cardiac (myofibrillar loss and dilatation of the sarcoplasmic reticulum) and renal (glomerular vacuolization, tubular damage and laboratory evidence of a nephrotic syndrome) lesions induced by all three agents had similar features. However, the cardiac lesions induced by losoxantrone and doxorubicin were significantly more severe (Billingham scores) than those produced by piroxantrone. The renal lesions induced by piroxantrone and losoxantrone were less severe than those produced by doxorubicin. Similarly losoxantrone and piroxantrone-induced intestinal alterations (denudation of epithelial layer and inflammatory cellular infiltration) were less severe than those occurring after treatment with doxorubicin. Both losoxantrone and piroxantrone were shown to form Fe(III): drug complexes that may cause oxidative damage to various tissues.

Laser photochemotherapy: a less invasive approach for treatment of cancer

The effectiveness of combining surgery with chemo- and radiation therapy in treatment of human cancer provides a useful model for further development of new multimodality approaches including laser photochemotherapy. Laser endoscopy often is a useful treatment for obstructive tumors in airways, but interstitial laser fiberoptics is becoming a more precise, minimally invasive alternative for ablation of unresectable or recurrent neoplasms. Combining intratumor chemotherapy with laser energy delivery via interstitial fiberoptics should be most effective using drugs activated by photothermal energy. A number of investigators have shown that anthracyclines and cis-platinum are likely candidates for light or heat activation in cancer cells. An advantage of anthracyclines is their dual role as antitumor drugs and as photosensitizers. Because they are effective chemotherapy agents without photoactivation, two approaches are possible to increase tumor responses. Maximum tolerated dose followed by photoillumination via laser fiberoptics can be used to obtain better tumor palliation. Improved treatment response to lower intratumor drug levels after laser activation also should reduce systemic toxicity. Preclinical studies and recent case reports from several groups suggest photochemotherapy with currently approved drugs and lasers may soon become an attractive alternative for treatment of recurrent tumors in cancer patients.

Detection and separation of the anthrapyrazole CI-941 and its metabolites in serum and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method using ion-pairing chromatography on reversed-phase C18 material with a mobile phase of acetonitrile-water (19:81, v/v) containing 5 mM 1-pentanesulfonic acid was developed for the detection and separation of the anthrapyrazole CI-941 (I) and its metabolites. After sample clean-up with solid-phase extraction, I and its metabolites were measurable at a wavelength of 491 nm. A detection limit of 5 ng/ml was achievable for I. The dicarboxylic acid derivative and the isomers of the monocarboxylic acid derivative could be separated. Application of the method to a human pharmacokinetic study showed two and four metabolites of I in serum and urine respectively.

Laser and daunomycin chemophototherapy of human carcinoma cells

Adriamycin and daunomycin anticancer drugs are detectable in leukemias and solid tumors by cell fluorescence. We observed initial cytoplasmic fluorescence followed by slow nuclear localization of adriamycin and daunomycin after incubation with cultured human squamous cell (P3, FADU) and adenocarcinoma (HT29, SW620) lines by digital video imaging microscopy. Tumor cells incubated with 10 mug/ml of these drugs exhibited increased uptake for more than 3 h with intracellular levels in the range 0.5-2.5 mug/10 6 cells measured by dimethyl sulfoxide (DMSO) extraction and fluorescence spectrophotometry. Daunomycin had 10- to 100-fold higher toxicity for these carcinoma cells than for normal human epithelial keratinocytes measured by in vitro MTT tetrazolium assays. The viability of daunomycin-sensitized carcinoma cells was decreased 2- to 10-fold further by argon laser illumination at 488 nm (5W, T max = 8 degrees C) for 2-3 minutes. The results suggest that adriamycin derivatives may be useful targeting agents for adjuvant treatment and chemophototherapy of human solid tumors by MR-guided laser fiberoptic endoscopy.