Norman M. Bleehen

Resistance modification by PSC-833, a novel non-immunosuppressive cyclosporin A

: A novel non-immunosuppressive cyclosporin [corrected], PSC-833, has been tested for its ability to circumvent resistance to doxorubicin, vincristine and colchicine in human and murine multidrug resistant (MDR) cell lines. This compound is shown to be a highly potent resistance modifier, being 7-10-fold more potent than the parent compound, cyclosporin A, whilst approximately equal to cyclosporin A in the growth inhibitory effects of compound alone. Reversal of the P-glycoprotein-associated MDR drug accumulation defect is a major component of resistance reversal for PSC-833, as it is for cyclosporin A.Abstract A novel non-immunosuppressive cyclosporin A, PSC-833, has been tested for its ability to circumvent resistance to doxorubicin, vincristine and colchicine in human and murine multidrug resistantant (MDR) cell lines. This compound is shown to be a highly potent resistance modifier, being 7–10-fold more potent than the parent compound, cyclosporin A, whilst approximately equal to cyclosporin A in the growth inhibitory effects of compound alone. Reversal of the P-glycoprotein-associated MDR drug accumulation defect is a major component of resistance reversal for PSC-833, as it is for cyclosporin A.

Intrinsic radiation sensitivity may not be the major determinant of the poor clinical outcome of glioblastoma multiforme

Abstract Purpose: Many radiobiologic mechanisms may contribute to the clinical radiation resistance of Glioblastoma Multiforme. One of them is considered to be an unusually low intrinsic radiation sensitivity. This is a collaborative study between three laboratories to evaluate the intrinsic radiation sensitivity of 85 cell lines derived from human malignant gliomas as the major cause of the poor clinical results of radiation treatment to these tumors. Methods and Materials: Fifty-one cell lines were early passage. The distribution by histologic type was: 58 glioblastoma, 17 anaplastic astrocytoma, six oligodendroglioma and four astrocytoma grade 2. The intrinsic radiation sensitivity will be expressed by the surviving fraction at 2 Gy (SF 2 ). The SF 2 has been determined for single dose irradiation for cell lines on exponential phase, under aerobic conditions, growing on plastic. The patient age, Karnofski Status, histological grade, survival, dose of irradiation for 50 patients are investigated for correlation with SF 2 of the corresponding newly established cell lines. Results: The mean SF 2 of the 85 cell lines was 0.46 (0.12 – 0.87). The mean SF 2 by histologic type was 0.50, 0.34, 0.54 and 0.38 for glioblastoma, anaplastic astrocytoma, oligodendroglioma and astrocytoma grade 2 cell lines, respectively. No correlation was found between SF 2 and the patient age or Karnofski status. The difference in SF 2 between the 58 glioblastoma and 17 anaplastic astrocytoma cell lines was significant p = 0.002. The difference in actuarial survival between glioblastoma and anaplastic astrocytoma patients was borderline of significance ( p = 0.08). The difference in SF 2 of cell lines derived from these two groups of patients was of borderline significance ( p = 0.08). The difference in radiation sensitivity for anaplastic astrocytoma and glioblastoma cell lines was clearly reflected in the difference in survival for the two groups of patients from where the cell lines were derived. However, no correlation was found between SF 2 and survival within each grade. In a multivariate analysis the age, grade and Karnofski status were found to be significant prognostic values for survival with a p values of 0.032, 0.03 and 0.038, respectively, however, the In SF 2 was not significant ( p = 0.40). The mean SF 2 of the 6 oligodendroglioma cell lines (0.54) was comparable to that of glioblastoma multiforme (0.50). The high SF 2 for oligodendroglioma does not accord with the much better clinical outcome of these tumors. Conclusions: These data on 85 malignant glioma cell lines show a very broad distribution of SFZ values for irradiation in vitro . SF 2 reflected the difference in sensitivity between AA (Grade 3) and GBM (Grade 4). This may suggest that the parameter SF 2 is useful to discriminate between the sensitivity of different grades or types of histology in vitro . However, SF 2 was not a predictor of the clinical outcome on individual basis for malignant gliomas. The in vitro studies will need to be supplemented by physiologic characterization of the tumors in vivo . Such conclusions would limit the predictive value of current radiation sensitivity assays based on in vitro dose-survival measurement for at least high grade malignant gliomas.

Expression of apoptosis-regulatory genes in lung tumour cell lines: relationship to p53 expression and relevance to acquired drug resistance

As a first step towards elucidating the potential role(s) of bcl-2 and bcl-2-related genes in lung tumorigenesis and therapeutic responsiveness, the expression of these genes has been examined in a panel of lung cancer cell lines derived from untreated and treated patients, and in cell lines selected in vitro for multidrug resistance. Bcl-2 was hyperexpressed in 15 of 16 small-cell lung cancer (SCLC) cell lines and two of five non-small-cell lung cancer (NSCLC) lines compared with normal lung and brain, and hyperexpression was not chemotherapy related. Bcl-x was hyperexpressed in the majority of SCLC and NSCLC cell lines as compared with normal tissues, and all lung tumour lines preferentially expressed bcl-x1-mRNA, the splice variant form that inhibits apoptosis. Bax gene transcripts were hyperexpressed in most SCLC and NSCLC cell lines examined compared with normal adult tissues. Mutant p53 gene expression was detected in the majority of the cell lines and no relationship between p53 gene expression and the expression of either bcl-2, bcl-x or bax was observed. No changes in bcl-2, bcl-x and bax gene expression were observed in multidrug-resistant cell lines compared with their drug-sensitive counterparts.

Neuroendocrine differentiation and clinical behaviour in non-small cell lung tumours

The present study examines the relationship between neuroendocrine (NE) differentiation and the clinical behaviour of non-small cell lung cancer (NSCLC). Retrospective (n = 315) and prospective (n = 44) cohorts of non-small cell tumours were obtained from surgically treated cases of lung cancer, comprising 218 squamous cell carcinomas, 65 adenocarcinomas, 51 adenosquamous carcinomas, and 25 large cell undifferentiated carcinomas. Paraffin wax embedded and fresh frozen tissue sections were stained for the NE markers neurone specific enolase, creatine kinase-BB, bombesin, neurotensin, chromogranin A, synaptophysin and UJ-13A. The expression of two or more markers was observed in 30% of cases, and was taken to identify NE-NSCLC. A statistically significant correlation between nodal status and NE differentiation (P = 0.05), and disease stage and NE differentiation (P = 0.04) was observed. However, there was no correlation between NE differentiation and survival. These findings suggest that NE-NSCLC, analogous to SCLC is more highly metastatic than non-NE-NSCLC.

Experimental and Clinical Aspects of Hyperthermia Applied to the Treatment of Cancer with Special Reference to the Role of Ultrasonic and Microwave Heating

Publisher Summary This chapter discusses that there is unequivocal evidence that moderate hyperthermia (41–45 °C) may kill cells in vitro and in vivo . There is some evidence that suggests that malignant cells may be more sensitive to heat than normal cells and subpopulations of tumor cells normally protected in vivo from radiation and drug treatment by hypoxia, poor blood supply, and other less well-defined factors may be particularly sensitive to heat. Hyperthermic treatment may act in a synergistic way with ionizing radiation and with some cancer chemotherapeutic agents. Therefore, the chapter discusses techniques available for inducing hyperthermia with particular reference to ultrasonic and microwave sources of energy. It also describes the factors that affect the response to heat such as the magnitude of temperature and duration and other modifying factors such as pH.

Establishment and characterisation of cell lines from patients with lung cancer (predominantly small cell carcinoma).

Tissue samples from 59 patients with lung cancer have been used to establish cell lines in culture. The primary diagnosis was small cell carcinoma in all except four. Most of the samples were of bone marrow but pleural effusions, lymph node biopsies and skin metastases were also included. The samples were usually split between HITES serum-free medium and HITES plus 2.5% foetal calf serum. A total of 19 cell lines were established and characterised. One line is large cell anaplastic lung carcinoma, four are B-lymphoblastoid and fourteen are small cell lung cancer. Considerable heterogeneity in gross morphology, neuroendocrine differentiation (by electron microscopy) and content of the enzyme L-dopa decarboxylase was seen. The use of HITES plus 2.5% foetal calf serum resulted in better establishment of cultures than did serum-free HITES.

RADIOSENSITIVITY TESTING OF HUMAN MALIGNANT GLIOMAS

Radiotherapy remains the main treatment modality for patients with malignant gliomas and is the only treatment which significantly prolongs survival. Clonogenic and tetrazolium based colorimetric assays (MTT) of early passage cultures have been performed following 2 Gy doses of x-rays in order to determine if in vitro radiosensitivity is a factor in response to treatment. Of 47 biopsies received, 39 were established in primary culture. A value of surviving fraction to 2 Gy (SF2) was obtained in 85% of growth assays and 64% of clonogenic assays. The mean SF2 value for the MTT was 0.56 which was significantly higher than the 0.42 obtained for the clonogenic assay. There was, however, reasonable qualitative agreement in assessing relative radiosensitivity/radioresistance (r = 0.7). Mean SF2 values for grade 3 tumors were 0.52 (MTT) and 0.35 (clonogenic) as against mean SF2 values of 0.63 (MTT) and 0.47 (clonogenic assay) for grade 4 tumors. In 24 patients with adequate follow-up, no direct correlation was found between SF2 and survival, although mean SF2 values for patients surviving greater than 18 months was significantly less (p = 0.01) than patients surviving less than 18 months as determined by the MTT assay.

A phase I study of the hypoxic cell radiosensitizer Ro-03-8799

The 2-nitroimidazole hypoxic cell radiosensitizer Ro-03-8799 has been suggested to have possible advantages over misonidazole with regard both to radiosensitization and toxicity on the basis of reported experimental work. The present work reports a Phase I escalating dose toxicity study of the drug. This has shown severe acute central neurotoxicity at high dose levels (greater than 1 g/m2). Initial results of a multiple-dose toxicity study indicate that 1 g/m2 is likely to be the maximum dose which may be given repeatedly. The plasma and tumor pharmacokinetics of the drug have been measured. The mean t 1/2 for 9 patients was 5.8 +/- 1.5 hr. Peak plasma concentration is linearly related to dose and at 1 g/m2 is 12.1 +/- 2.3 micrograms/ml (n = 6). Human tumor drug concentrations have been measured after single doses of 1 g/m2 given to 8 patients with a variety of tumors. Peak tumor concentrations of drug of 11.7-81.6 micrograms/g were found. Because of acute, dose-limiting toxicity related to individual doses it may not be possible to achieve, in human tumors, concentrations of drug that offer significant advantage over misonidazole in terms of radiosensitizing efficiency. No evidence of chronic cumulative toxicity was observed at the doses employed.

Radiotherapy for lung cancer

The role of radiation therapy in the management of lung cancer was reviewed at a workshop held in Cambridge, England, in June 1984. It was concluded that there was a continuing role for radiation therapy in the primary management of small cell lung cancer, including the loco-regional treatment for patients with limited disease. Radical radiotherapy for patients with non-small cell carcinoma could be curative for a proportion of patients with limited disease. Careful planning and quality control was essential. Palliative radiotherapy provided useful treatment for many other patients. Other related aspects of treatment are also presented.

Pentoxifylline: its pharmacokinetics and ability to improve tumour perfusion and radiosensitivity in mice

The pharmacokinetics of pentoxifylline and its three major metabolites were measured after intraperitoneal administration of 10 mg/g or 100 mg/kg of drug in C3H mice. Peak concentrations of pentoxifylline were approximately 10 and 100 micrograms/ml, respectively, with elimination half-lives (+/- 2 SE) of 4.6 (4.2-5.1) and 7.5 (7.2-7.9) min, respectively. Plasma concentrations of the pharmacologically active hydroxy metabolite were approximately one-tenth those of the parent compound. In vitro evidence of the ability of pentoxifylline to increase blood cell deformability indicates that concentrations of up to 30 micrograms/ml can increase deformability of both red and white blood cells; doses between 5 mg/kg and 100 mg/kg were therefore tested 15 min after administration to test the effect of the drug on tumour and normal tissue perfusion, tumour radiosensitivity and renal function immediately after exposure to appropriate drug concentrations. Using 86Rb extraction, doses of 10-100 mg/kg pentoxifylline were shown to increase relative tumour perfusion of the RIF-1 tumour to 140-170% of control, with no effect in skin, muscle, kidney, liver or lung, but with similar increases in spleen perfusion; there was no significant effect in any tissue after 5 mg/kg. Using a clonogenic assay, this increased tumour perfusion was shown to be reflected in increased tumour radiosensitivity to 25 Gy 15 min after pentoxifylline, with the same dose threshold of 10 mg/kg, and similar lack of dose-dependence at higher doses; the response indicated reduction in hypoxic fraction by a factor of 2-3. Renal function, measured by [51Cr]EDTA and [125I]iodohippurate clearance was unaffected at doses up to 50 mg/kg, with a slight effect at 100 mg/kg. The data indicate that pentoxifylline is effective at increasing relative tumour perfusion, with minimal effects on other tissues, and this increase is reflected in improved radiosensitivity. The doses at which the drug is effective are compatible with the mechanism being modification of blood cell deformability. Pentoxifylline shows promise as a clinical radiosensitiser acting by direct increase in tumour oxygenation.