Developing a clinically relevant radiosensitizer for temozolomide-resistant gliomas

The prognosis for patients with glioblastoma (GB) remains grim. Concurrent temozolomide (TMZ) radiation—the cornerstone of glioma control—extends the overall median survival of GB patients by only a few months over radiotherapy alone. While these survival gains could be partly attributed to radiosensitization, this benefit is greatly minimized in tumors expressing O⁶-methylguanine DNA methyltransferase (MGMT), which specifically reverses O⁶-methylguanine lesions. Theoretically, non-O⁶-methylguanine lesions (i.e., the N-methylpurine adducts), which represent up to 90% of TMZ-generated DNA adducts, could also contribute to radiosensitization. Unfortunately, at concentrations attainable in clinical practice, the alkylation capacity of TMZ cannot overwhelm the repair of N-methylpurine adducts to efficiently exploit these lesions. The current therapeutic application of TMZ therefore faces two main obstacles: (i) the stochastic presence of MGMT and (ii) a blunted radiosensitization potential at physiologic concentrations. To circumvent these limitations, we are developing a novel molecule called NEO212—a derivatization of TMZ generated by coupling TMZ to perillyl alcohol. Based on gas chromatography/mass spectrometry and high-performance liquid chromatography analyses, we determined that NEO212 had greater tumor cell uptake than TMZ. In mouse models, NEO212 was more efficient than TMZ at crossing the blood-brain barrier, preferentially accumulating in tumoral over normal brain tissue. Moreover, in vitro analyses with GB cell lines, including TMZ-resistant isogenic variants, revealed more potent cytotoxic and radiosensitizing activities for NEO212 at physiologic concentrations. Mechanistically, these advantages of NEO212 over TMZ could be attributed to its enhanced tumor uptake presumably leading to more extensive DNA alkylation at equivalent dosages which, ultimately, allows for N-methylpurine lesions to be better exploited for radiosensitization. This effect cannot be achieved with TMZ at clinically relevant concentrations and is independent of MGMT. Our findings establish NEO212 as a superior radiosensitizer and a potentially better alternative to TMZ for newly diagnosed GB patients, irrespective of their MGMT status.

γ-H2AX kinetics as a novel approach to high content screening for small molecule radiosensitizers

BACKGROUND

Persistence of γ-H2AX after ionizing radiation (IR) or drug therapy is a robust reporter of unrepaired DNA double strand breaks in treated cells.

METHODS

DU-145 prostate cancer cells were treated with a chemical library ±IR and assayed for persistence of γ-H2AX using an automated 96-well immunocytochemistry assay at 4 hours after treatment. Hits that resulted in persistence of γ-H2AX foci were tested for effects on cell survival. The molecular targets of hits were validated by molecular, genetic and biochemical assays and in vivo activity was tested in a validated Drosophila cancer model.

RESULTS

We identified 2 compounds, MS0019266 and MS0017509, which markedly increased persistence of γ-H2AX, apoptosis and radiosensitization in DU-145 cells. Chemical evaluation demonstrated that both compounds exhibited structurally similar and biochemical assays confirmed that these compounds inhibit ribonucleotide reductase. DNA microarray analysis and immunoblotting demonstrates that MS0019266 significantly decreased polo-like kinase 1 gene and protein expression. MS0019266 demonstrated in vivo antitumor activity without significant whole organism toxicity.

CONCLUSIONS

MS0019266 and MS0017509 are promising compounds that may be candidates for further development as radiosensitizing compounds as inhibitors of ribonucleotide reductase.

Synthesis, in vitro anticancer screening and radiosensitizing evaluation of some new 4-[3-(substituted)thioureido]-N-(quinoxalin-2-yl)-benzenesulfonamide derivatives

Sulfonamides and quinoxaline derivatives possess many types of biological activities and have been recently reported to show substantial antitumor activity. This paper reports the synthesis of novel thioureido sulfaquinoxaline derivatives. All the newly synthesized compounds were evaluated for their in vitro anticancer activity against a human liver cell line (HEPG2) and showed higher activity than the reference drug doxorubicin. 4-(3-(4-Ethylbenzoate) thioureido)-N-(quinoxalin-2-yl)benzenesulfonamide (9) (IC₅₀ = 15.6 μmol L⁻¹), N-(pyridin-2-yl)-4-(3-(4-(N-quinoxalin-2-yl-sulfamoyl)phenyl)thioureido)benzenesulfonamide (10) (IC₅₀ = 26.8 μmol L⁻¹) and N-(quinoxalin-2-yl)-4-(3-(4-(N-thiazol-2-ylsulfamoyl)phenyl)thioureido)benzenesulfonamide (11) (IC₅₀ = 24.4 μmol L⁻¹) were the most potent compared to doxorubicin (IC₅₀ = 71.8 μmol L⁻¹). The most potent compounds 9, 10 and 11 were evaluated as radiosensitizing agents by subjecting the compounds to γ-irradiation (8 kGy).

Validated spectrophotometric and spectrofluorimetric methods for determination of chloroaluminum phthalocyanine in nanocarriers

UV-VIS-Spectrophotometric and spectrofluorimetric methods have been developed and validated allowing the quantification of chloroaluminum phthalocyanine (CIAIPc) in nanocarriers. In order to validate the methods, the linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and selectivity were examined according to USP 30 and ICH guidelines. Linearities range were found between 0.50-3.00 microg x mL(-1) (Y = 0.3829 X [CIAIPc, microg x mL(-1)] + 0.0126; r = 0.9992) for spectrophotometry, and 0.05-1.00 microg x mL(-1) (Y = 2.24 x 10(6) X [CIAIPc, microg x mL(-1)] + 9.74 x 10(4); r = 0.9978) for spectrofluorimetry. In addition, ANOVA and Lack-of-fit tests demonstrated that the regression equations were statistically significant (p<0.05), and the resulting linear model is fully adequate for both analytical methods. The LOD values were 0.09 and 0.01 microg x mL(-1), while the LOQ were 0.27 and 0.04 microg x mL(-1) for spectrophotometric and spectrofluorimetric methods, respectively. Repeatability and intermediate precision for proposed methods showed relative standard deviation (RSD) between 0.58% to 4.80%. The percent recovery ranged from 98.9% to 102.7% for spectrophotometric analyses and from 94.2% to 101.2% for spectrofluorimetry. No interferences from common excipients were detected and both methods were considered specific. Therefore, the methods are accurate, precise, specific, and reproducible and hence can be applied for quantification of CIAIPc in nanoemulsions (NE) and nanocapsules (NC).

Assessment of chemical purity of 10B-enriched p-boronophenylalanine by high-performance liquid chromatography coupled on-line with inductively coupled plasma optical emission spectrometry

A dual-detection technique, consisting of a combination of reversed-phase high-performance liquid chromatography and on-line detection of elemental boron in the column effluents by inductively coupled plasma optical emission spectrometry, was tested for drug analysis. The method was applied to assessing the chemical purity of p-boronophenylalanine (BPA), isotopically enriched in 10B. This compound is employed as a fructose complex solution for biodistribution studies in laboratory and clinical trials of boron neutron capture therapy. Besides the determination of the content of BPA, required for chemical quality controls of solutions of the complex used for infusions, resolution of mixtures of BPA and two usually accompanying residual impurities (phenylalanine and tyrosine) was achieved with UV detection. The limits of detection (in solution) were 1.5 and 0.6 ng ml-1, respectively. In addition, by monitoring a sensitive-element emission wavelength it was possible to jointly observe the elution of boron-containing compounds that may be transparent to UV radiation or to confirm the presence of boron in potential impurities accompanying the drug. Those impurities may arise from the BPA synthesis or may be produced by degradation during the aging of the solutions. Chromatographic peaks corresponding to the amino acids and also to a related inorganic compound were detected in BPA-fructose complex solutions that were stored for different times and under different conditions. An increase in the areas of the peaks attributed to tyrosine and phenylalanine was observed for BPA-fructose solutions stored refrigerated for 1 month to 1 year, suggesting that degradation processes able to reduce the amount of bioavailable BPA could be active.

Can dietary furanocoumarin ingestion enhance the erythemal response during high-dose UVA1 therapy?

As phototoxic skin reactions caused by psoralen are induced by wavelengths within the UVA1 spectrum, we assessed the potential of the small amount of psoralen in a normal diet to provoke phototoxicity in volunteers with skin types I and II. Threshold erythema was unaffected by ingestion of a 200-g portion of parsnip.

In vivo absorption spectroscopy of tumor sensitizers with femtosecond white light

A system based on a femtosecond white-light continuum and a streak camera was used for recordings of the in vivo absorption spectra of the tumor-seeking agent disulphonated aluminum phthalocyanine. Measurements for different drug doses were performed on tumor tissue (muscle-implanted adenocarcinoma) and normal muscle tissue in rats. It was found that the shape of the spectrum is tissue dependent. The peak of the absorption spectrum is blueshifted in tumor tissue as compared with the muscle. Thus the contrast in the drug-related absorption can be altered by up to a factor of 2 from the primary drug molecular-concentration contrast between normal muscle and tumor by the proper selection of the illumination wavelength.

The immunohistochemical assessment of hypoxia, vascularity and proliferation in bladder carcinoma

BACKGROUND AND PURPOSE

Hypoxia and proliferation are important determinants of radiation responsiveness; prospective measures of these before radiotherapy may enable individualisation of treatment schedules. Immunohistochemical techniques offer a potential means of achieving this in routine biopsy material.

MATERIAL AND METHODS

Cellular hypoxia as measured by pimonidazole fixation and immunohistochemistry has been evaluated in a series of human bladder cancers with dual staining of sections for pimonidazole and either the vascular markers, CD31/34, or proliferation markers, Ki-67 or cyclin A. Twenty one tumour specimens were examined suitable for the double staining technique.

RESULTS

The median hypoxic fraction was 9% (range 0-38). Seven tumours did not stain for pimonidazole and 11 exhibited necrosis. The mean vascular density ranged from 16.7 to 160.6 vessels per mm2. The median hot spot count was 30 (range 16-43). There was a statistically significant increase in vessel density in hypoxic compared to oxic regions measured by both vessel density (P = 0.02) and hot spot count (P = 0.004). Proliferation indices decreased from oxic to hypoxic areas close to blood vessels.

CONCLUSIONS

We have demonstrated that bladder cancer exhibits a range of hypoxia, proliferation and vascular density which may be used to form the basis for patient selection for hypoxia modification, accelerated radiotherapy and vascular targeting agents.

Intracellular localization of the radiation enhancer motexafin gadolinium using interferometric Fourier fluorescence microscopy

Motexafin gadolinium (MGd) is a unique therapeutic agent that localizes in cancer cells and increases tumor response to ionizing radiation and certain chemotherapeutics. The in vitro intracellular localization, accumulation, and retention of MGd in murine EMT6 mammary sarcoma and Rif-1 fibrosarcoma cell lines were studied using interferometric Fourier fluorescence microscopy. MGd cellular uptake was semiquantified using its characteristic fluorescence emission band centered at 758 nm. Colocalization studies were performed using mitochondrial, endoplasmic reticulum, Golgi apparatus, nuclear, and lysosomal fluorescent organelle probes, and verified using interferometric Fourier spectroscopy. Cellular uptake was gradual and increased significantly with incubation time. MGd localized primarily within the lysosomes and endoplasmic reticulum, and to a lesser extent within the Golgi apparatus and mitochondria. Mitochondrial staining was increased in media without serum. No nuclear uptake was detected in the Rif-1 cells, but after 48 h nuclear uptake was observed in 15% of EMT6 cells. These results indicated that MGd accumulates within cytoplasmic compartments. The sustained intracellular localization of MGd may, in part, account for its unique radiation and chemotherapy enhancement properties. Interferometric Fourier fluorescence microscopy is a potentially powerful tool in delineating and verifying localization sites of therapeutic agents.

Analysis of 76Br-BrdU in DNA of brain tumors after a PET study does not support its use as a proliferation marker

76Br-bromodeoxyuridine has previously been suggested as a PET tracer to characterize proliferation potential. However, in animal studies a large fraction of the tissue radioactivity is due to 76Br-bromide, which remains extracellular for extensive periods and contributes significantly to the level of radioactivity. The present project aimed at investigating whether in human brain tumors, sufficient amounts of 76Br-bromodeoxyuridine would be incorporated into DNA, to motivate further attempts with this tracer. Eight patients with brain tumors: 3 meningiomas, 2 astrocytoma grade IV, 1 astrocytoma oligodendroglioma grade II-IV and 2 metastases, were examined with PET and 76Br-BrdU on three occasions: immediately after injection of the tracer, at 4-6, and at 18-20 hours after administration. After the first PET study, diuresis was introduced and maintained for about 12 hours. About 20 hours after tracer administration, 200 mg/m(2) bromodeoxyuridine was administered to 7 patients median 5.8 (range 1-22) hours prior to operation allowing the immunohistochemical analysis of the proliferation potential. During the operation, tumor samples were taken and radioactivity in DNA extracted and measured. The uptake of radioactivity was higher in the tumors than in brain parenchyma. However, in the operative samples only 1-27% (average: 9%) of the radioactivity was found in the DNA fraction. The plasma radioactivity remained high throughout the study with only minimal signs of elimination by the diuresis. 76Br-BrdU is extensively metabolized to 76Br-bromide, and only a minor fraction of the radioactivity is found in the DNA fraction, making it unlikely that this tracer can be used for assessment of proliferation potential.

Hypoxia in a human intracerebral glioma model

OBJECT

The development of hypoxia in human gliomas is closely related to functional vasculature and the presence of hypoxia has important biological and therapeutic consequences. Assessment of hypoxia is necessary to understand its role in treatment response and to evaluate treatment strategies to improve tumor oxygenation. In this study, the authors report findings of their analysis of the degree of hypoxia in relation to other vascular parameters in a human intracerebral glioma xenograft.

METHODS

In sections of tumor, hypoxic regions were identified immunohistochemically by using the hypoxic marker pimonidazole. The S-phase marker bromodeoxyuridine was used to detect cell proliferation, and the perfusion marker Hoechst 33342 was used to delineate perfused vessels. Vascular structures were stained with an endothelial marker. Hypoxic tumor regions were clearly present in this human intracerebral glioma model. Hypoxic areas were usually found in nonperfused regions, whereas tumor cell proliferation was especially marked in perfused tumor areas. Furthermore, by using in situ hybridization the authors identified infiltrating tumor cells in the normal brain. This feature is often observed in gliomas in patients.

CONCLUSIONS

This model is a representative human glioma model that provides the researcher with the opportunity to analyze the relationship between the degree of hypoxia and vascular parameters, as well as to examine the effects of treatments aimed at modification of the oxygenation status of a tumor.

Alteration of sensitivity of intratumor quiescent and total cells to gamma-rays following thermal neutron irradiation with or without 10B-compound

PURPOSE

Changes in the sensitivity of intratumor quiescent (Q) and total cells to gamma-rays following thermal neutron irradiation with or without 10B-compound were examined.

METHODS AND MATERIALS

5-Bromo-2'-deoxyuridine (BrdU) was injected to SCC VII tumor-bearing mice intraperitoneally 10 times to label all the proliferating (P) tumor cells. As priming irradiation, thermal neutrons alone or thermal neutrons with 10B-labeled sodium borocaptate (BSH) or dl-p-boronophenylalanine (BPA) were administered. The tumor-bearing mice then received a series of gamma-ray radiation doses, 0 through 24 h after the priming irradiation. During this period, no BrdU was administered. Immediately after the second irradiation, the tumors were excised, minced, and trypsinized. Following incubation of tumor cells with cytokinesis blocker, the micronucleus (MN) frequency in cells without BrdU labeling (= Q cells at the time of priming irradiation) was determined using immunofluorescence staining for BrdU. The MN frequency in the total (P + Q) tumor cells was determined from the tumors that were not pretreated with BrdU before the priming irradiation. To determine the BrdU-labeled cell ratios in the tumors at the time of the second irradiation, each group also included mice that were continuously administered BrdU until just before the second irradiation using mini-osmotic pumps which had been implanted subcutaneously 5 days before the priming irradiation.

RESULTS

In total cells, during the interval between the two irradiations, the tumor sensitivity to gamma-rays relative to that immediately after priming irradiation decreased with the priming irradiation ranking in the following order: thermal neutrons only > thermal neutrons with BSH > thermal neutrons with BPA. In contrast, in Q cells, during that time the sensitivity increased in the following order: thermal neutrons only < thermal neutrons with BSH < thermal neutrons with BPA. The longer the interval between the two irradiations, the higher was the BrdU-labeled cell ratio at the second irradiation. The labeled cell ratio at the same time point after each priming irradiation increased in the following order: thermal neutrons only < thermal neutrons with BSH < thermal neutrons with BPA.

CONCLUSION

These findings indicated that the use of 10B-compound, especially BPA, in thermal neutron irradiation causes the recruitment from the Q to P population.

Development of a chiral HPLC method to evaluate in vivo enantiomeric inversion of an unstable, polar radiosensitizer in plasma

A chiral HPLC method to quantify in vivo enantiomeric inversion of prodrug CI-1010 (IR) or its drug IIR (PD 146923), a radiosensitizer, upon X-irradiation of dosed rats was developed. These polar enantiomers were separated only by using normal-phase chiral HPLC. A Chiralpak AS column provided the best separation. Isolation of analytes from plasma employed solid-phase extraction (SPE), and required conditions that were compatible with normal-phase HPLC. Options for SPE were restricted by the chemically reactive nature of both prodrug and drug, which produced analyte losses as high as 100%. Acceptable recoveries using SPE required evaluation of conditions for analyte chemical stability. The validated method gave a lower-limit of quantitation (LLOQ) of 200 ng/ml for each enantiomer extracted from 0.15 ml of plasma. The LLOQ of the inverted enantiomer could be detected in the presence of 10,000 ng/ml of the dosed enantiomer. Precision (RSD) ranged from 14.2 to 4.4%, and from 24.2 to 5.1% for IIS and IIR, respectively. Accuracy (RE) was +/- 13.1 and +/- 13.2%, respectively. Recoveries ranged from 44.3 to 71.4%, and from 40.7 to 67.9%, for IIS and IIR, respectively.

Proton nuclear magnetic resonance measurement of p-boronophenylalanine (BPA): a therapeutic agent for boron neutron capture therapy

Noninvasive in vivo quantitation of boron is necessary for obtaining pharmacokinetic data on candidate boronated delivery agents developed for boron neutron capture therapy (BNCT). Such data, in turn, would facilitate the optimization of the temporal sequence of boronated drug infusion and neutron irradiation. Current approaches to obtaining such pharmacokinetic data include: positron emission tomography employing F-18 labeled boronated delivery agents (e.g., p-boronophenylalanine), ex vivo neutron activation analysis of blood (and very occasionally tissue) samples, and nuclear magnetic resonance (NMR) techniques. In general, NMR approaches have been hindered by very poor signal to noise achieved due to the large quadrupole moments of B-10 and B-11 and (in the case of B-10) very low gyromagnetic ratio, combined with low physiological concentrations of these isotopes under clinical conditions. This preliminary study examines the feasibility of proton NMR spectroscopy for such applications. We have utilized proton NMR spectroscopy to investigate the detectability of p-boronophenylalanine fructose (BPA-f) at typical physiological concentrations encountered in BNCT. BPA-f is one of the two boron delivery agents currently undergoing clinical phase-I/II trials in the U.S., Japan, and Europe. This study includes high-resolution 1H spectroscopic characterization of BPA-f to identify useful spectral features for purposes of detection and quantification. The study examines potential interferences, demonstrates a linear NMR signal response with concentration, and presents BPA NMR spectra in ex vivo blood samples and in vivo brain tissues.

Pharmacokinetics of nicotinamide in cancer patients treated with accelerated radiotherapy: the experience of the Co-operative Group of Radiotherapy of the European Organization for Research and Treatment of Cancer

BACKGROUND

The EORTC has initiated studies to combine nicotinamide with carbogen in accelerated fractionation schedules (ARCON), since for some tumour types, acute and chronic hypoxia as well as treatment protraction may prejudice the outcome of radiotherapy. The tolerable dose of nicotinamide and the optimal interval for administration need to be ascertained.

AIM

Full pharmacokinetic profiles of nicotinamide concentrations in plasma were analyzed repeatedly in 15 patients to determine the inter- and intra-patient variability in peak plasma concentrations and the optimum times for administering nicotinamide as a radiosensitizer.

METHODS

Nicotinamide (Nicobion) was administered in tablet form to patients with advanced head and neck and non-small cell lung carcinomas. A standard 6 g dose was given regardless of body weight after an overnight fast and at least 30 min before breakfast. In 15 patients, blood samples were taken prior to and 1, 2, 4, 6, 8, 12 and 24 h after administration of the drug. This full profile was determined on two to four occasions for the head and neck cancer patients and on two occasions for the lung cancer patients. For each profile, the maximum concentration of nicotinamide (Cmax), time to peak plasma concentration (Tmax), elimination half-lives (t1/2) and area under the curve (AUC) were determined. Compliance was recorded and nausea and vomiting were graded on a 0-3 scale. Complete profiles of the five major metabolites were also obtained.

RESULTS

In the 48 complete sets of blood samples, peak plasma concentrations ranged from 787 to 2312 nmol/ml with a median value of 1166 nmol/ml. The peak plasma concentration was achieved at 1 h in only 54% of the pharmacokinetic profiles, but at this time 92% of the profiles had already exceeded the target concentration of 700 nmol/ml, the level required in the mouse for tumour radiosensitization. The median t1/2 for all 15 cases was 9.3 h, with minimum and maximum values of 4.2 and 26.8 h. The highest concentrations of nicotinamide metabolites were found to be the N-oxide, 2-pyridone and 1-methylnicotinamide. The toxicity (nausea and vomiting) was scored and found not to be correlated with any of the pharmacokinetic parameters.

CONCLUSIONS

The plasma concentrations considered necessary to radiosensitize can easily be exceeded with a dose of 6 g taken as 12 x 500 mg in tablet form; 700 nmol/ml was achieved in all patients and apparently would have been achieved in most even with a considerable reduction in dose. An adequate time between administration and radiotherapy appeared to be 1 h with this drug formulation for 92% of the profiles.

Positron emission tomography-based boron neutron capture therapy using boronophenylalanine for high-grade gliomas: part I

Determination of tumor boron-10 (10B) levels is required for accurate neutron dosimetry during boron neutron capture therapy. We assessed a new method for quantitative measurement of boronated drug uptake in high-grade gliomas. This method uses positron emission tomography (PET) with fluorine-18-labeled L-fluoroborono-phenylalanine (L-18F-10B-FBPA), which was synthesized as an analogue of L-boronophenylalanine. We studied the accumulation of L-18F-10B-FBPA by PET in patients with high-grade gliomas. Dynamic PET studies of brain tumors revealed that L-18F-10B-FBPA accumulated gradually after bolus injection, and the value of PET activity divided by the integrated plasma activity reached a constant level 42 min after injection, which was defined as the incorporation constant (Ic*). This constant reflected the appropriate L-18F-10B-FBPA accumulation in tumor tissue. Based on the Ic* constant, the methods for estimating tumor 10B concentration were devised. With this method, the estimated values of 10B concentration in gliomas were very close to the 10B levels in surgical specimens. This method was based solely on PET and can potentially provide data that would assist in the selection of patients for future treatment with boron neutron capture therapy after surgical resection of their brain tumors.

An automated multidimensional screening approach for rapid method development in high performance liquid chromatography

Despite enormous advancements in the area of high performance liquid chromatography (HPLC) in recent years, method development remains a major challenge. This is primarily due to the unknown nature of the matrix material which sometimes is difficult to characterize (e.g. biological matrices). To improve the efficiency of method development a multidimensional screening approach was presented. This approach was based on two major steps: (1) a matrix spiked with drug was eluted from a large number of columns, each under different mobile phase compositions, to provide the preliminary selectivity-separation information; (2) this information was then used to compose column switching pairs (each pair consisted of a preparatory column followed by an analytical column) and the elution profile was evaluated to determine the suitable clean up and quantitation conditions. An example was provided using ethyl 3,5-bis(acetylamino)-2,4,6-triiodobenzoate (EEDA), an X-ray enhancement agent, in human plasma. Since the HPLC system was fully automated the data generation time, and consequently the method development time, can be significantly reduced.

An HPLC assay utilizing solid-phase extraction for CI-1010, an alkylating radiosensitizer, in rat plasma

CI-1010, a 2-nitroimidazole, is a chiral prodrug for the active moiety PD 146923 and is under development as an alkylating radiosensitizer to be used as an adjuvant to radiotherapy. Because CI-1010 has an estimated half-life < or = 2 min under physiological conditions its metabolites/degradation products PD 146415, an inactive moiety, and PD 146923 were assayed to support rat toxicology studies. The method involves the processing of plasma samples through phenyl solid-phase extraction cartridges followed by chromatography on CN columns with UV detection at 325 nm. The assay appears linear over the range 0.050-100 micrograms ml-1 for both PD 146415 and PD 146923. Interrun accuracy and precision estimates for PD 146415 and PD 146923 were within +/- 6.50 and < or = 3.27%, respectively, and +/- 12.8 and < or = 4.06%, respectively, for quality controls containing nominal concentrations of 0.400, 4.00 and 40.0 micrograms ml-1. The absolute recovery of CI-1010, PD 146415 and internal standard, PD 126675, were approximately 40, 96 and 95%, respectively. The recovery of PD 146923 appeared concentration dependent and ranged from 68 to 92%. PD 146415 and PD 146923 were both stable in rat plasma at 4 degrees C and -77 degrees C for at least 7 h and 154 days, respectively. CI-1010 was not stable in rat plasma at 4 degrees C. CI-1010, PD 146415 and PD 126675 were stable for at least 63 days in 10 mM phosphate buffer at pH 3.0 and 4 degrees C. Under identical conditions PD 146923 was stable for only 8 days. The applicability of this method to determine concentrations of PD 146415 and PD 146923 in rat plasma is reported in this paper.

Management of nonmatrix interfering peaks in a chiral high-performance liquid chromatographic assay produced by solid-phase extraction of rat plasma

PD 146923, under evaluation as an alkylating radiosensitizing drug, contains one chiral center and one chemically reactive aziridine ring. A method was developed to evaluate possible in vivo enantiomeric inversion of PD 146923 in rat plasma. Normal-phase chiral HPLC was necessary to separate the enantiomers, but a typical aqueous-based solid-phase extraction (SPE) was needed to isolate the analytes from plasma. SPE at higher analyte concentrations removed all interfering peaks and gave acceptable recoveries. However, peaks (A-G) from seven new components interfering with analyte detection at lower concentrations were produced by SPE. The interfering peaks overlapped each other, so some were not observed until other, more intense interfering peaks had been managed. The low separation efficiency of the chiral column precluded management of interfering peaks by modifying chromatographic parameters. Chemical reactivity of the analytes forced the use of mild conditions for management of interfering peaks. Peaks A-F were: (A) water from the SPE cartridge; (B) SPE sorbent endcapping; (C, E and F) nonvolatile salts of the SPE elution acid reacting with bases from the injection solvent or with unidentified bases from the SPE cartridge; (D and G) analyte degradation products. This study identifies the nonmatrix peaks coeluting with the analytes, and describes how an aqueous-based SPE method was developed for isolating these very polar, highly reactive analytes in plasma for separation in a normal-phase chiral HPLC assay. Additionally, B, C, E or F probably are present in many other solid-phase extractions, but are not observed because of polarity or solubility properties.

Hypericin: a new laser phototargeting agent for human cancer cells

Laser activation of anthracycline-related drugs combines chemotherapy with photoablation for improved treatment. Hypericin, a structurally related anthraquinone, was tested for laser activation and cytotoxicity in human cancer cells. Viability of P3 squamous cell carcinoma cells incubated with 1 to 20 microgram/mL hypericin was reduced by more than 95% after 1 minute exposure at 4 degrees C to an argon laser (514 nm, 5 W), a KTP-532 laser (532 nm, 5 W), or a 20-A xenon lamp. Viability was reduced over 90% in six human carcinoma, sarcoma, and melanoma cell lines by this combined treatment, but only trace toxicity was seen after separate exposure to hypericin or light alone. These results show that hypericin is a sensitive agent for phototherapy of human cancer cells in vitro and indicate that this drug may be useful for tumor targeting via minimally invasive imaging-guided laser fiber optics.

Development of bioreductive markers for tumour hypoxia

Hypoxic cells in tumours can be identified by exposing them to an immunologically identifiable 2-nitroimidazole (NITP) with a theophylline substituent which becomes bioreductively metabolised and binds to cellular macromolecules in the absence of oxygen. A range of monoclonal and polyclonal antibodies raised against theophylline or caffeine can identify cells containing bound adducts of NITP, in some cases with higher specificity than the standard product used. An alternative approach utilizes the very high specificity of FITC-avidin as a reagent to detect metabolic binding of a 2-nitroimidazole with a biotinylated side-chain (NIB), with the advantage of a single-step staining protocol. Both proliferating and hypoxic cell populations within tumours can be identified by simultaneous staining for incorporation of NITP and BrdUrd and this has shown that some cells incorporate both markers, suggesting that there is some overlap between the proliferating and hypoxic cell compartments.

The effect of transurethral light on the canine prostate after sensitization with the photosensitizer tin (II) etiopurpurin dichloride: a pilot study

A pilot study was undertaken to determine the effect of transurethral light on photosensitized periurethral prostatic tissue in the dog. Initial studies demonstrated that a sufficient level of the photosensitizer tin (II) etiopurpurin dichloride, SnET2, was present in the canine prostate 24 hours after intravenous administration to create a photodynamic effect. Gross and histologic examination of SnET2 photosensitized prostates treated transurethrally with 285 joules per cm. of red light (660 nm.) showed hemorrhagic necrosis as much as 1 cm. from the urethral wall. Three weeks after treatment, circumferential glandular atrophy was evident within the treatment area. The urethral mucosa, which was histologically absent at the 48-hour interval, regenerated by 3 weeks. Transurethral photodynamic treatment of the prostate is feasible, and its use for the treatment of benign prostatic hyperplasia warrants further investigation.

Laser-induced fluorescence studies of meso-tetra(hydroxyphenyl)chlorin in malignant and normal tissues in rats

meso-Tetra(hydroxyphenyl)chlorin (mTHPC) is an attractive second-generation dihydroporphyrin photosensitiser for use in photodynamic therapy. In this study, 1.3 mg kg-1 body weight mTHPC was administered intravenously, and laser-induced fluorescence was used to characterise and compare its localisation and retention in different rat tissues, including an induced experimental adenocarcinoma, 24 h and 48 h post injection. These studies were performed in an attempt to predict the anatomical locations where mTHPC PDT might be most effective and suggest suitable injection--irradiation intervals in each case. Of particular interest were the intra-abdominal and intrathoracic tissues. The fluorescence was induced at 405 nm and the fluorescence spectrum in the region 450-750 nm was analysed. All collected spectra were dominated by the fluorescence signature of mTHPC with its peak at 652 nm, and all values in this study are in terms of background-free drug-specific fluorescence intensity at that wavelength. The photosensitiser accumulated in high concentrations in the tumour and the reticuloendothelial system. Muscular organs, such as the heart and the abdominal wall, were characterised by a low drug fluorescence signature.

Laser-induced fluorescence in malignant and normal tissue in mice injected with two different carotenoporphyrins

Laser-induced fluorescence (LIF) was used to characterise the localisation of an intravenously administered trimethylated carotenoporphyrin [CP(Me)3] and a trimethoxylated carotenoporphyrin [CP(OMe)3] in an intramuscularly transplanted malignant tumour (MS-2 fibrosarcoma) and healthy muscle in female Balb/c mice, 3, 24, 48 and 96 h post injection. The fluorescence was induced with a dye laser pumped by a nitrogen laser, emitting light at 425 nm. The fluorescence spectra were recorded in the region 455-760 nm using a polychromator equipped with an image-intensified CCD camera. The tumour/peritumoral muscle ratio was about 5:1 for CP(Me)3 and about 6:1 for CP(OMe)3 in terms of the background-free fluorescence intensity, which peaked at about 655 nm. By including the endogenous tissue fluorescence, the contrast was further enhanced by a factor of approximately 2.

Determination of 5,10,15,20-tetra-(m-hydroxyphenyl)chlorin in tissues by high performance liquid chromatography

A procedure for the extraction and high performance liquid chromatographic (HPLC) determination of the photodynamic therapeutic agent 5,10,15,20-tetra(m-hydroxyphenyl)chlorin in human, rat and mouse tissues following intravenous administration of the drug is described. The tissue (tumour, skin, muscle and liver) was homogenized and extracted into a mixture of methanol:dimethyl sulphoxide:water (32:8:1 by vol.) containing, 5,10,15,20-tetra(p-hydroxyphenyl)chlorin as the internal standard. The precipitated proteins were removed by centrifugation and the supernatant was separated by reversed phase HPLC on a Hypersil-ODS column with 77% (v/v) acetonitrile in 0.1% trifluoroacetic acid as the mobile phase. The solute was detected with high sensitivity and specificity by a UV-VIS detector set at 423 nm.

Selectivity of boron carriers for boron neutron capture therapy: pharmacological studies with borocaptate sodium, L-boronophenylalanine and boric acid in murine tumors

Borocaptate sodium (BSH) and L-boronophenylalanine (L-BPA) are two boron carriers used for boron neutron capture therapy (BNCT) in the treatment of glioblastoma and melanoma, respectively. The suitability of these two compounds was evaluated on the basis of pharmacokinetic studies aiming at characterizing their biodistribution, tumor uptake and tumor selectivity. Boric acid was also used as a reference compound since it is nonselective and relatively freely diffusible. The compounds were investigated in two tumor models, a B16 pigmented melanoma and the RIF1 sarcoma. Mice were sacrificed after different boron doses at various post-injection times and tissue and plasma levels measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The proposed minimum effective tumor boron concentration of 15 ppm was achieved in both tumor models for the three compounds tested, although only for L-BPA in the melanoma was this achieved when tumor-plasma ratios were above 1. In the RIF1 model, maximum tumor concentrations of 44 and 31 ppm B were reached after administration of 50 micrograms B/g body weight for boric acid and BSH, respectively. After administration of 12.5 micrograms B/g of L-BPA, maximum concentrations of 15 and 21 ppm were found in the RIF1 and B16 models, respectively. Tumor-plasma ratios (TPR) for BSH remained close to or below unity at all times studied in both tumors. Brain levels of BSH were very low, however, leading to tumor-brain ratios markedly greater than 1 at all times. L-BPA and boric acid showed TPR values above unity in both tumor models, reaching 3.2 in B16.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of potent photosensitizers in human tumor LOX by means of laser scanning microscopy

By means of laser scanning fluorescence microscopy the intratumoral localization patterns of several photosensitizers in LOX tumors in nude mice were studied. Lipophilic dyes such as TPPS1 (tetraphenylporphine monosulfonate), TPPS2a (tetraphenylporphine disulfonates with the sulfonate groups on adjacent rings), AlPCS1 (aluminium phthalocyanine monosulfonate) and AlPCS2 (aluminium phthalocyanine disulfonates) localized mainly in tumor cells. The fluorescence intensity of these dyes increased from 4 h to 48 h postinjection and the fluorescence was still observable 120 h postinjection. The more hydrophilic dyes such as TPPS3 (tetraphenylporphine trisulfonates), TPPS4 (tetraphenylporphine tetrasulfonates), and AlPCS4 (aluminium phthalocyanine tetrasulfonates) localized mainly extracellularly in the tumorous stroma. The fluorescence intensity of these dyes decreased from 4 h to 48 h postinjection. 120 h postinjection no significant fluorescence of these dyes could be seen in the tumors. P-II (Photofrin II), 3-THPP [tetra(3-hydroxyphenyl)porphine], TPPS2o (tetraphenylporphine disulfonates with the sulfonate groups on opposite rings) and AlPCS3 (aluminum phthalocyanine trisulfonates) had a combined localization pattern, i.e. a strongly cytoplasmic membrane-localizing pattern and a weakly intracellular distribution pattern, although some fluorescence could be seen in the tumorous stroma. The data are discussed in relation to what is known about the in vivo photosensitizing efficiency of some of the dyes.

Clearance of S-(3-amino-2-hydroxypropyl) phosphorothioate (WR-77913) in rats

Complications of radiotherapy in the treatment of retinal and choroidal neoplastic diseases include cataract formation, radiation retinopathy, neovascular glaucoma, cystoid macular edema, and subretinal neovascularization. These side effects may be minimized by the use of compounds known to have a protective effect on normal ocular tissues without impeding the benefits of therapy. Phosphorothioates, first developed under the Antiradiation Drug Development Program of the U.S. Army Medical Research and Development Command, have been reported to protect normal tissues during radiation therapy in a variety of animal models. One of the phosphorothioates, WR-77913 (S-[3-amino-2-hydroxylpropyl]phosphorothioate) was found to inhibit cataract formation in rats after radiation exposure. To test the efficacy of WR-77913 in the retina, we established a high-pressure liquid chromatography method to measure the levels of dephosphorylated WR-77913 and studied the drug's clearance from the lens, retina, blood, kidney, and liver in rats.

Lysosomal localization and mechanism of uptake of Nile blue photosensitizers in tumor cells

Nile blue derivatives have been shown to be potentially effective photosensitizers for photodynamic therapy of malignant tumors. Results of a previous study suggested that the high accumulation of these dyes in cells may be the result of dye aggregation, partition in membrane lipids, and/or sequestration in subcellular organelles. In this report, results of studies are presented from an investigation of the subcellular localization and mechanism of accumulation of these dyes in cells in vitro. A video-enhanced fluorescence microscopy was used, and a punctate pattern of fluorescence was seen, most of which was localized in the perinuclear region with extracellular dye concentrations between 1 to 100 nM. These particles resembled characteristic particles identified by standard lysosomal dyes. At higher dye concentrations (1 microM or above), fluorescence in the perinuclear region was too intense to resolve into discrete cellular structures, while fluorescence in other cellular structures including mitochondria and cytomembranes was visible. At even higher dye concentrations (10-100 microM), Nile blue derivatives were seen with a light microscope as blue particles, the size and location of which resembled the punctate fluorescence described above. Results which further suggest that the lysosome is the main site of dye localization include (a) histochemical staining of dye-loaded cells with the lysosomal marker enzyme acid phosphatase, which showed similar localization of the enzyme-staining and dye-containing particles, (b) phototreatment of dye-loaded cells which obliterated the majority of the acid phosphatase-stained particles, and (c) treatments with agents affecting the membrane pH gradient reduced the uptake and enhanced the efflux of dyes, while agents that alter cellular membrane potentials had no effect on dye accumulation. The uptake of the dyes was partially inhibited by inhibitors of oxidative phosphorylation indicating that at least part of the process is energy dependent. These findings, together with previous results showing that the cellular uptake of these dyes is highly concentrative and proportional to the extracellular dye concentration over a wide range, are consistent with the hypothesis that the dyes are mainly localized in the lysosomes via an ion-trapping mechanism. Results of the present study also suggest that the lysosomes may be an intracellular target for photodynamic killing of tumor cells mediated by Nile blue photosensitizers and that lysosomotropic photosensitization may be a strategy for effective and selective destruction of tumor cells.

Hydrophobicity-dependent fluorescence properties and intracellular fluorospectroscopic behavior of phototoxic drugs

Fluorospectroscopic behavior of chlorpromazine, mequitazine, afloqualone and piroxicam, which are known to induce skin photosensitivity, was examined in both homogeneous solutions and human buccal mucosal cells. Each drug showed large Stokes' shifts and their fluorescence intensities increased in hydrophobic solvents. These results indicated that the drugs tested can be used as hydrophobic fluorescence probes. Fluorescence microscopic observations of buccal mucosal cells treated with these drugs showed that all the drugs, especially chlorpromazine and mequitazine, were distributed in intracellular membranous regions.

Localization of potent photosensitizers in human tumor LOX by means of laser scanning microscopy

By means of laser scanning fluorescence microscopy the intratumoral localization patterns of several photosensitizers in LOX tumors in nude mice were studied. Lipophilic dyes such as P-II (Photofrin II), 3-THPP tetra(3-hydroxyphenyl)porphin, TPPS1 (tetraphenylporphine monosulfonate), TPPS2a (tetraphenylporphine disulfonates with the sulfonate groups on adjacent rings), A1PCS1 (aluminium phthalocyanine monosulfonate) and A1PCS2 (aluminium phthalocyanine disulfonates) localized mainly in tumor cells. The fluorescence intensity of these dyes increased from 4 h to 48 h post-injection and the fluorescence was still observable 120 h post-injection. The more hydrophilic dyes such as TPPS2o (tetraphenylporphine disulfonates with the sulfonates groups on opposite rings), TPPS3 (tetraphenylporphine trisulfoantes), TPPS4 (tetraphenylporphine tetrasulfonates), A1PCS3 (aluminium phthalocyanine trisulfonates) and A1PCS4 (aluminium phthalocyanine tetrasulfonates) localized mainly extracellularly in the tumorous stroma. The fluorescence intensity of these dyes decreased from 4 h to 48 h post-injection. 120 h post-injection no significant fluorescence of these dyes could be seen in the tumors. The data are discussed in relation to what is known about the in vivo photosensitizing efficiency of some of the dyes.

In vitro and in vivo fluorescence monitoring of photosensitizers

The use of steady state fluorescence spectroscopy in the detection and monitoring of potential photochemotherapeutic agents is examined. Problems associated with both in vitro and in vivo fluorescence measurements are investigated, and typical data are presented. Recent results on the use of fluorescence in pharmacokinetic studies are discussed, and the relative merits of in vitro vs. in vivo methods are outlined.

Electronic spectra of hypocrellin A, B and their derivatives

In this paper, the electronic spectra of hypocrellin A and B (HA and HB) are studied in detail. It has been proved that their three visible absorption bands come respectively from the pi pi transition of their conjugated systems and intramolecular proton transfer. In dilute solutions, their fluorescence spectra consist of the fluorescence peak of the neutral monomolecule and that of the zwitter-ions that are formed through proton transfer of excited states. In concentrated solution, the longer wavelength emission band is composed of the overlapped fluorescence peaks of zwitter-ions and excimers. The fluorescence spectra of the crystalline hypocrellin A and B consist of the fluorescence peaks of zwitter-ions and excimers and the fluorescence of neutral monomolecules could could not be observed. Their relative intensities are closely related to the excitation wave-length.

NMR study on the major components in hematoporphyrin derivative YHPD

The hematoporphyrin derivative YHPD, a China-made product, has been clinically used in photodynamic therapy of tumors as a good photosensitizing drug. The NMR study on the structure of its major components is reported here. In terms of high performance liquid chromatography (HPLC) four major components A, B, C and D were isolated. The NMR results showed that the component A is O-acetylhematoporphyrin, B and C are two isomers of vinyldeuteroporphyrin. The spectra of 2-dimensional homonuclear correlation NMR, 2-dimensional NOE (nuclear overhauser enhancement), 13C-NMR and off-resonance as well as FAB (fast atom bombarding) mass spectrum of component D indicate that it is a protoporphyrin dimer linked by carbon-carbon bond. This finding may provide a chemical basis for understanding the difference in biological activity between YHPD and other foreign commercial HPD, as well as the composition of clinically used alkali-treated HPD and its effective component.

Demonstration of tumor-selective retention of fluorinated nitroimidazole probes by 19F magnetic resonance spectroscopy in vivo

We have evaluated two fluorinated misonidazole analogues, Ro 07-0741 and CCI-103F, as potential probes for the non-invasive identification of hypoxic tumor cells by 19F magnetic resonance spectroscopy (MRS) in vivo. The equipment used was a 1.9 T Oxford Research Systems TMR-32 spectrometer, fitted with a 15 mm diameter surface coil. Signal was readily detectable, with similar intensity from EMT6 tumor, liver, and brain at early times (1-2 hr) after i.v. injection in BALB/c mice, indicative of an initial uniform biodistribution of parent probes. At later times (5-10 hr) there was a progressive reduction in signal intensity from brain and liver, but tumor levels remained constant or declined more slowly. This is illustrated by tumor/brain ratios at 6-7 hr of 2.9 (Ro 07-0741) and 4.2 (CCI-103F). In 4/5 mice analyzed at 20-24 hr after Ro 07-0741, and 1/2 following CCI-103F, tumor signal remained detectable. This occurred in the absence of parent probe as measured by HPLC, suggesting the involvement of a product of nitroreductive bioactivation. Studies with KHT and RIF-1 tumors in C3H/He mice showed a similar trend but retention in RIF-1 was less dramatic, and this was consistent with the known hypoxic fractions and comparative in vivo nitroreductase activities. These promising results support the continuing development of 19F nitroimidazole probes for non-invasive identification of hypoxic cells in vivo.

[PSD-007 luminescence in the diagnosis of exfoliative cells from malignant tumors]

This paper presents the first report in China on the use of luminescence method with hematoporphyrin derivative PSD-007 in the analysis of the exfoliative malignant cells. By this method, pleurorrhea and ascites from 226 suspicious patients were detected. The results showed that its positive rate was 42.23% higher than that of Wright's stain and its positive conformation rate to HE stain could reach as high as 90.2%. Especially, cancer cells could be distinguished from various kinds of non-cancer cells by an objective quantitative analysis of the cellular fluorescent intensity using microfluorophotometer. This new method, being simple, economical and highly specific, is used not only in the qualitative study of the exfoliative tumor cells, but also in the quantitative analysis.

Biological studies on the main fractions of hematoporphyrin derivative

The four main fractions of hematoporphyrin derivative were separated by high-pressure liquid chromatography. Each fraction was studied with respect to photosensitizing capabilities, fluorescence, and tumor tissue uptake in mice bearing EMT-6 tumors. Animals received i.p. injections of 10 mg/kg of each fraction, and 24 h later tumors either were treated with 100 J/cm2 of light (630 nm) to evaluate photosensitizing capabilities, or the animals were sacrificed and tumors removed for fluorescence and fraction uptake determination. The results indicate that the fraction responsible for photosensitization has the highest tumor tissue uptake and retention. Furthermore, this fraction demonstrates the highest overall fluorescence localization in neoplastic tissue. The other poorly photosensitizing fractions have a lower overall fluorescence in vivo due to their poor tumor tissue localization.

Spectroscopic, morphologic, and cytotoxic studies on major fractions of hematoporphyrin derivative and Photofrin II

This study characterizes the special properties of hematoporphyrin derivative (HpD) (Photofrin I) and Photofrin II with respect to the absorption and fluorescence spectra of the subfractions of the compounds in both solution and cells. In addition, data are presented demonstrating variation in the spectral amplitudes with respect to the age (shelf-life) of the commercially available compounds. Data are also presented confirming that fraction III is the active ingredient-containing fraction with respect to photosensitivity. The morphologic and electron microscopic analyses demonstrate that the first visible effect on cells following porphyrin sensitization can be detected within 1 minute of low level light exposure (10 J/cm2, 630 nm). The initial sites of morphologic damage are the mitochondria.

Fluorescent microscopy of hematoporphyrin derivative in the nude mouse tumor model

Mechanisms for localization of hematoporphyrin derivative (HPD) within malignant tissue and for tumor necrosis after photodynamic therapy have not yet been established with certainty. We describe a modified freeze-drying technique to study these mechanisms. Normal tissues and squamous cell carcinoma xenografts were examined in nude mice after administration of HPD. Skin reveals marked fluorescence in connective tissue cells. No fluorescence is visible in surface epithelial cells or keratin. Liver shows diffuse fluorescence only in cells lining sinusoids. In tumor, malignant cells do not fluoresce and connective tissue cells fluoresce brilliantly. This technique provides a clear view of HPD fluorescence, frozen instantaneously in location and time. Fluorescence from connective tissue cells in skin and tumor suggests that localization and photodynamic action may be targeted in part at cells that critically support malignant epithelial cell growth as well as at malignant epithelial cells directly.

Measurements of glutathione and other thiols in cells and tissues: a simplified procedure based on the HPLC separation of monobromobimane derivatives of thiols

Although there is intense interest in the role of thiols in controlling the efficiency of radiosensitizers, and in developing thiols (or pro-drugs liberating thiols) as radioprotectors, there is little information regarding the concentration of specific thiols in cells, tumors and normal tissues. Details are presented of a modified procedure using the thiol binding agent monobromobimane with separation using paired-ion reverse phase high performance liquid chromatography (HPLC). This method has been extended to include measurements of the radiosensitizer misonidazole and its desmethylated metabolite Ro 05-9963 in tissues.

Tumor-localizing and photosensitizing properties of the main components of hematoporphyrin derivative

Both 3H-labeled and unlabeled hematoporphyrin derivative (HPD) were analyzed by high-pressure liquid chromatography (HPLC) and gel permeation chromatography. Four main components were isolated by HPLC, and two were isolated by gel permeation chromatography. The tumor-localizing ability of each component was tested and compared to that of 67Ga and 3H2O by injection in mice bearing Lewis lung carcinoma. The photosensitizing abilities of the HPLC-separated components in vitro were also tested. Finally, porphyrin extracts of tumors from mice given HPD were analyzed by HPLC. The tumor-localizing ability of the components increased with decreasing polarity. While crude HPD localized in tumor tissue only to the same extent as did 3H2O, Component 7 was almost as effective as was 67Ga in localizing in the tumor. The cellular uptake of HPD components increased with decreasing polarity. In accordance with this, the low-polarity components were the most effective photosensitizers.

High-performance liquid chromatographic analysis of the new hypoxic cell radiosensitiser, Ro 03-8799, in biological samples

A high-performance liquid chromatographic method of analysis with UV detection has been developed to measure levels of a new radiosensitiser, Ro 03-8799 and its N-oxide metabolite, in biological fluids and tissues. The accuracy and precision of the method have been determined in both plasma and urine, where the limits of quantitation are 100 and 500 ng/ml, respectively. Typical results are presented from a human volunteer study where samples were analysed by this method. Important aspects of the method, involving both sample handling techniques and chromatographic conditions are discussed.

Quantitation of hematoporphyrin derivative in human gliomas, experimental central nervous system tumors, and normal tissues

A simple and reproducible method of quantitating the amount of hematoporphyrin derivative by fluorescence microscopy in biopsies of tumors from patients undergoing photoradiation therapy is presented, substantiated by laboratory studies of experimental central nervous system tumors and normal rat tissues. The literature regarding the quantitation of hematoporphyrin is reviewed, and implications of this study for the future application of photoradiation therapy and the design of laboratory studies are discussed.