Potentiation of radiation-induced regrowth delay in murine tumors by fludarabine

Fludarabine (9-beta-D-arabinofuranosyl-2-fluoroadenine-5'-monophosphate), an adenine nucleoside analogue, has previously been shown to inhibit the repair of radiation-induced chromosome damage. Thus fludarabine may have therapeutic utility in combination with photon irradiation. The purpose of this study was to determine whether fludarabine could enhance radiation-induced murine tumor regrowth delay and to determine the most effective dose and schedule of the combination. A significant (P < 0.05) absolute regrowth delay enhancement was observed in three murine tumor models (SA-NH, a sarcoma; and MCA-K and MCA-4, mammary carcinomas) when fludarabine (800 mg/kg) was given 1 h prior to 25 Gy gamma-irradiation. While fludarabine enhanced radiation-induced tumor regrowth delay when given between -36 h and +6 h of radiation (SA-NH tumor), the greatest enhancement was observed when fludarabine was given at -24 h prior to irradiation (radiation dose modification factor of 1.82 at -24 h compared to 1.57 at -3 h prior to radiation). The degree of fludarabine enhancement (at -3 or -24 h) was dose dependent at doses above 200 mg/kg. When fludarabine and radiation were administered on a fractionated schedule (fludarabine given 3 h prior to radiation each day for 4 days), the dose modification factor increased to 2.14 (1.63 if the effect of fludarabine alone is subtracted). These results suggest that fludarabine enhances radiation-induced tumor regrowth delay in a more than additive fashion after both single and fractionated treatments, and the degree of enhancement is dependent on the sequence and timing of administration, the fludarabine dose, and the tumor type. Thus, fludarabine may have clinical potential as a radiation enhancer in the treatment of solid tumors.     

Radioprotective effects of diltiazem on cytogenetic damage and survival in gamma ray exposed mice

Diltiazem, a calcium ion channel blocker, already in use in cardiovascular therapeutics, has been observed to protect against bone marrow damage (cytogenetic damage, cell death) and mortality in whole body irradiated mice. The micronuclei fraction in bone marrow cells of whole body irradiated (60Co gamma rays, 2.0 Gy) mice was reduced from 2.24 +/- 0.23% to about 0.74 +/- 0.33% by preirradiation administration (-20 min) of 110 mg/kg body wt. diltiazem (ip). Endogenous colony forming unit counts in spleen of mice administered 110 mg/kg body wt. (-20 min) of diltiazem before 10 Gy whole body irradiation were 6 times more than untreated irradiated controls. Pretreatment with diltiazem accelerated the recovery of radiation induced weight loss also. Diltiazem (110 mg/kg body wt, -20 min) enhanced 30 day survival to about 95% and 85% after lethal whole body absorbed dose of 9 and 10 Gy respectively and also mitigated radiation induced life- span shortening. Post-irradiation (10 Gy) administration of diltiazem (+20 to 30 min) enhanced survival from about 2 to 15% only but was highly significant (P < 0.001). Possible modes of radioprotective action of diltiazem have been discussed.     

The response of Dunning R3327 prostatic adenocarcinoma to IL-2, histamine and radiation

A syngeneic, androgen-sensitive Dunning R3327 rat prostatic adenocarcinoma was transplanted bilaterally in the flanks of male Copenhagen Fisher rats. Approximately 3 months after implantation, when the tumours had a median volume of 150 mm3, one group of rats was treated with histamine alone (4 mg kg(-1) subcutaneously on week days), another group with human recombinant interleukin 2 (IL-2) alone (425 IU kg(-1) continuous infusion) and a third group with both histamine and IL-2 during 6 weeks. Tumours on one flank were irradiated (6 Gy once daily for 3 days to a total dose of 18 Gy) beginning 1 week after the onset of treatment with histamine and/or IL-2. The contralateral tumour served as the intra-animal control. The tumour volumes were determined weekly. The growth curves showed that all three drug treatments were effective in delaying growth, but when used individually did not cause tumour shrinkage. Radiation was the most effective single agent, but when used alone the shrinkage did not occur until 2 weeks after irradiation. When combined with the drugs, more rapid and extensive growth delay and/or shrinkage was seen. The growth curves showed clear differences between the different treatments. The combination of the three agents was the most effective of all. The most striking difference between radiation alone and radiation plus biotherapy was the time at which a tumour response was detectable. Thus, active biotherapy alone and especially in a combination with histamine and radiotherapy warrants further investigation as a potential therapeutic approach to prostate cancer.     

Iron supplementation enhances response to high doses of recombinant human erythropoietin in preterm infants

AIMS: To determine whether iron supplementation would enhance erythropoiesis in preterm infants treated with high doses of human recombinant erythropoietin (r-HuEPO). METHODS: Sixty three preterm infants were randomly allocated at birth to one of three groups to receive: r-HuEPO alone, 1200 IU/kg/week (EPO); or r-HuEPO and iron, 1200 IU/kg/week of r-HuEPO plus 20 mg/kg/week of intravenous iron (EPO + iron); or to serve as controls. All three groups received blood transfusions according to uniform guidelines. RESULTS: Infants in the EPO + iron group needed fewer transfusions than controls--mean (95% CI) 1.0 (0.28-1.18) vs 2.9 (1.84-3.88) and received lower volumes of blood--mean (95% CI) 16.7 (4.9-28.6) vs 44.4 (29.0-59.7) ml/kg. The EPO group also needed lower volumes of blood than the controls--mean (95% CI) 20.1 (6.2-34.2) vs 44.4 (29.0-59.7) ml/kg, but the same number of transfusions, 1.3 (0.54-2.06) vs 2.9 (1.84-3.88). Reticulocyte and haematocrit values from postnatal weeks 5 to 8 were higher in the EPO + iron than in the EPO group, and both groups had higher values than the controls. Mean (SEM) plasma ferritin was lower in the EPO group-65 (55) micrograms/l than in the EPO + iron group 780 (182) micrograms/l, and 561 (228) micrograms/l in the control infants. CONCLUSIONS: Early administration of high doses of r-HuEPO with iron supplements significantly reduced the need for blood transfusion. Intravenous iron (20 mg/kg/week in conjunction with r-HuEPO yielded a higher reticulocyte count and haematocrit concentration after the forth week of life than r-HuEPO alone. Infants treated with r-HuEPO alone showed signs of reduced iron stores.     

Weekly paclitaxel and cisplatin with concurrent radiotherapy in locally advanced non-small-cell lung cancer: a phase I study

PURPOSE: Both cisplatin (CDDP) and paclitaxel have shown good antitumor activity in non-small-cell lung cancer (NSCLC) patients and are able to potentiate the antitumor effects of radiation therapy (RT). This study aimed to determine the maximum-tolerated doses (MTDs) of CDDP and paclitaxel (escalated alternately) when given concurrently with RT and to define the nature of the dose-limiting toxicity (DLT). PATIENTS AND METHODS: Chemotherapy-naive patients with locally advanced NSCLC received six weekly administrations of a CDDP-paclitaxel combination with concurrent local RT. The starting doses of CDDP and paclitaxel were 30 mg/m2/wk and 35 mg/m2/wk, respectively. RT was initially given at the dose of 1.2 Gy twice daily for 5 days per week for 5 weeks (total dose, 60 Gy) and at a single daily dose of 2 Gy for 5 days per week for 6 weeks in the last two cohorts of patients. The drug doses were escalated alternately until DLT occurred in more than one third of the patients in a given cohort. RESULTS: Overall, 25 patients were recruited through five different cohorts. All were assessable for toxicity. Esophagitis was the main toxicity and occurred in 16 of 25 patients (64%) and was grade 3 or 4 in five of them. At step 3 (CDDP 35 mg/m2/wk and paclitaxel 45 mg/m2/wk), two of five patients had to discontinue treatment because of severe esophagitis and one of these died of complications related to grade 4 esophagitis. However, keeping the same doses of chemotherapy and replacing hyperfractionation with a standard single-day fraction, weekly doses of CDDP and paclitaxel of 35 mg/m2 and 45 mg/m2 could be safely administered. Neutropenia was by far the most relevant hematologic toxicity and occurred in 33 of 141 weekly delivered courses, but it was of grade 4 in only four courses. Substantial pulmonary or neurologic toxicity was not observed in this study. Two complete responses (CRs) and 13 partial responses (PRs) were observed, for a 60% overall response rate (95% confidence interval [CI], 39% to 79%). The median survival time was 16 months, with a 66% 1-year survival probability. CONCLUSION: CDDP 35 mg/m2/wk and paclitaxel 45 mg/m2/wk can be safely administered with concurrent standard RT. The use of hyperfractionation is associated with a more frequent occurrence of severe esophagitis and requires a reduction of the CDDP dose to 30 mg/m2/ wk. Only future randomized trials will elucidate which of these two approaches (standard or hyperfractionated RT) is the better option to improve the outcome of patients with locally advanced NSCLC.     

Induction thermochemotherapy increases therapeutic gain factor for the fractionated radiotherapy given to a mouse fibrosarcoma

PURPOSE: It has been shown that thermochemotherapy (TC) given prior to radiation reduces the number of clonogens, with a resultant decrease in the tumor control radiation dose. The purpose of this article was to investigate using an animal tumor model how this clonogen reduction affects subsequent fractionated radiotherapy, including repopulation of surviving clonogens, and whether the induction TC can increase the therapeutic gain factor (TGF). METHODS AND MATERIALS: The single-cell suspensions prepared from the fourth-generation isotransplants of a spontaneous fibrosarcoma, FSa-II, were transplanted into the C3Hf/Sed mouse foot. TC was given by heating tumors at 41.5 degrees C for 30 min immediately after an intraperitoneal injection of cyclophosphamide (200 mg/kg) when tumors reached an average diameter of 4 mm. Fractionated radiotherapy (R) with equally graded daily doses was initiated 24 h after TC either in air (A) or under hypoxic conditions (H). The 50% tumor control dose (TCD50) and the radiation dose to induce a score 2.0 reaction (complete epilation with fibrosis) in one-half of irradiated animals, RD50(2.0), were obtained, and the TGF was calculated. Our previous results on the fractionated radiotherapy using the same tumor system served as controls. RESULTS: The TCD50(A, single dose) and TCD50(H, single dose) following TC+R were 52.2 and 57.3 Gy, respectively, which were 14.0 and 20.4 Gy lower than those following radiation alone. The TCD50(A, TC+R) increased only slightly when the number of fractions was increased from one to 10 doses, and all TCD50s were significantly lower than the TCD50(A, R alone). Both TCD50(H, TC+R) and TCD50(H, R alone) increased consistently from a single dose to 20 doses, but all TCD50(H, TC+R) were significantly lower than the TCD50(H, R alone). Regarding the normal tissue reaction, the RD50 values both following TC+R and R alone increased consistently from a single dose to 20 daily doses. However, the RD50(TC+R) and RD50(R alone) for each corresponding number of fractions was not significantly different, resulting in the TGFs significantly > 1.0 for combined TC+R treatments, with the exception of 20 daily doses given in air. CONCLUSION: The induction TC decreased the TCD50 values substantially without altering the RD50 for a late reaction, resulting in an significant increase in the TGF. These results encourage the use of TC as an induction treatment prior to fractionated radiotherapy.     

Enhancement of radiation-induced hepatic microsomal epoxide hydrolase gene expression by oltipraz in rats

The effects of radiation exposure in conjunction with oltipraz, a chemopreventive agent, on the expression of the gene encoding hepatic microsomal epoxide hydrolase (mEH) were examined in rats. Rats exposed to a single dose of 3 Gy gamma rays exhibited timerelated changes in the hepatic mEH mRNA level. Whereas the mEH mRNA level was transiently decreased at 3 and 8 h after irradiation, the mRNA levels were increased 3- to 4-fold at 15 to 48 h postirradiation, returning to the level in untreated animals at 72 h. Treatment of rats with oltipraz resulted in 1- to 19-fold increases in hepatic mEH mRNA levels 24 h post-treatment at doses of 5-200 mg/kg. Although treatment with oltipraz at a dose of 30 mg/kg affected the mEH mRNA level minimally (i.e. approximately 2-fold), 3 Gy whole-body irradiation along with oltipraz treatment resulted in a 9-fold increase in the mEH mRNA level at 24 h post-treatment. Treatment of animals with both oltipraz and 3 Gy gamma radiation for 3 consecutive days resulted in a 7-fold increase in mEH mRNA, showing that the increases in mEH mRNA were enhanced by the combination treatment. In rats irradiated with 3 Gy for 5 consecutive days, however, the mEH mRNA level failed to increase due to cell injury. Studies were further designed to assess the effects of 0.5 Gy ionizing radiation and concomitant oltipraz treatment. RNA blot analysis showed that mEH mRNA levels failed to be significantly altered at 3, 8, 15, 24 and 48 h after a single dose of 0.5 Gy. Nonetheless, exposure of animals to 0.5 Gy daily for 3 to 5 consecutive days caused a 3-fold elevation in the hepatic mEH mRNA level. Furthermore, treatment of animals with both oltipraz (30 mg/kg/day) and 0.5 Gy of gamma rays resulted in an enhanced elevation in the mEH mRNA level at 24 h post-treatment compared to the individual treatment, resulting in a 7-fold relative increase. The enhanced expression of hepatic mEH mRNA by 0.5 Gy gamma radiation and oltipraz was also observed after treatment for 3 to 5 days (8- to 6-fold relative increases). Western immunoblot analyses showed that hepatic microsomes produced from the rats treated with 0.5 Gy daily for 3 to 5 days resulted in a approximately 2-fold induction of hepatic mEH and that rats exposed to radiation in combination with oltipraz showed 3-fold increases in the liver mEH protein. Thus the relative increase in mEH mRNA levels was consistent with the expression of the protein. These results demonstrate that ionizing radiation causes alterations in hepatic mEH gene expression with the induction of the protein and that the mEH gene expression is enhanced by oltipraz treatment.     

Twelve-year experience with the 19 mm Carpentier-Edwards pericardial aortic valve

BACKGROUND: The purpose of the present study was to investigate the therapeutic effectiveness of interleukin-2 (IL-2) and interferon (IFN), either alone or in combination, in comparable groups of patients affected by advanced renal cell carcinoma (RCC). PATIENTS AND METHODS: In order to limit selection biases, treatment was allocated on a random basis. Patients randomized to IL-2 alone were scheduled to receive eight rlL-2 24-hour i.v. infusion cycles, days 1 to 4, at a daily dose of 18 x 10(6) lU/m2 for a total of 25 weeks. Patients randomized to IFN alone were scheduled to receive rIFN-alpha at a daily dose of 6 x 10(6) IU/m2, days 1, 3 and 5, every week for a total of 52 weeks. Patients randomized to the combination of IFN and IL-2 were given the same drugs at the same daily doses for a total of 24 weeks. Drug dose was modified according to toxicity. RESULTS: Twenty-three percent (95% CI:+/-17.5) of patients treated with IL-2 alone showed an objective response to treatment (9% CR). The corresponding figures in patients treated with IFN alone or IFN plus IL-2 were 9% (95% CI:+/-11.9) and 9% (95% CI:+/-11.9), respectively. Complete responses were observed only in patients treated with IL-2. The median duration of response in the IL-2 arm was 18 months (range, 9.5-24). The duration of the two responses achieved by IFN alone was seven and nine months, respectively. The corresponding figures in the two patients responding to the combination of IFN with IL-2 were 19 and 27 months, respectively. Total IL-2 dose appeared to be a major predictor of response. Only a minority of patients experienced grade 3-4 toxicity, the incidence being higher in those treated with IL-2 or IL-2 plus IFN. CONCLUSIONS: Neither IFN nor IL-2 or the combination of the two appear to be very active in patients with advanced RCC, even when trial entry was restricted to patients with relatively indolent disease. This stresses the need for the development of new approaches.     

Specificity of the BAX polymerase chain reaction system for detection of the foodborne pathogen Listeria monocytogenes

PURPOSE: The purpose of this study was to evaluate the toxicity and efficacy of twice-daily external irradiation to the pelvis and para-aortics with brachytherapy and concurrent chemotherapy for carcinoma of the cervix with positive para-aortic lymph nodes. METHODS AND MATERIALS: This study was designed to administer twice-daily radiation doses of 1.2 Gy to the pelvis and para-aortics at 4- to 6-h intervals, 5 days per week. The total external radiation doses were 24 to 48 Gy to the whole pelvis, 12 to 36 Gy parametrial boost, and 48 Gy to the para-aortics with an additional boost to a total dose of 54 to 58 Gy to the known metastatic para-aortic site. One or two intracavitary applications were performed to deliver a total minimum dose of 85 Gy to point A. Cisplatin (75 mg/m2, days 1 and 22) and 5-FU (1000 mg/m2/24 h x 4 days; days 1 and 22) were given for two or three cycles. RESULTS: Twenty-nine patients with clinical Stages I to IV carcinoma of the cervix with biopsy-proven para-aortic lymph nodes were enrolled in this study. Hyperfractionated external radiotherapy was completed in 86% (25 of 29). Brachytherapy was given in two applications to 48% (14 of 29), 31% (9 of 29) had one intracavitary application, 14% (4 of 29) had no brachytherapy, one had three applications, and one had five HDR applications. Radiotherapy was completed per protocol in 69%. Three courses of chemotherapy were given to 24% (7 of 29), 72% (21 of 29) received two courses, and one patient did not receive chemotherapy. The acute toxicity from chemotherapy was Grade 1 in 3%, Grade 2 in 17%, Grade 3 in 48%, and Grade 4 in 28%. Radiotherapy toxicity was Grade 1 in 7%, Grade 2 in 34%, Grade 3 in 21%, and Grade 4 in 28%. One Grade 5 toxicity occurred and the patient died from a myocardial infarction from chemotherapy and radiotherapy colitis during her course of therapy. The median follow-up time was 18.9 months. The overall survival estimates were 59% at 1 year and 47% at 2 years. The probability of local-regional failure was 38% at 1 year and 49% at 2 years. The probability of disease failure at any site was 45% at 1 year and 59% at 2 years. CONCLUSION: The results suggest that twice-daily external irradiation to the pelvis and para-aortics with brachytherapy and concurrent chemotherapy resulted in an unacceptably high rate (31%, 9 of 29) of Grade 4 nonhematologic toxicity. One patient died from complications of therapy. Radiotherapy was completed per protocol in 69%. The survival estimates appear no better than standard fractionation radiotherapy without chemotherapy. Additional follow-up is necessary for long-term survival estimates.     

Radiotherapy and concomitant weekly 1-hour infusion of paclitaxel in the treatment of head and neck cancer--results from a Phase I trial

PURPOSE: To define the maximum tolerated dose (MTD) by describing the dose-limiting toxicity (DLT) of weekly paclitaxel (PAC) given as a 1-h I.V. infusion in patients with head and neck cancer concomitant to irradiation. METHODS AND MATERIALS: Patients with unresectable or incompletely resected head and neck cancer were enrolled into a prospective, dose-escalating Phase I study. Toxicity was graded according to the WHO toxicity score. MTD dose was defined when two out of six patients developed DLT. The starting dose of PAC was 20 mg/m2 once weekly I.V. over 60 min, with a subsequent dose escalation of 10 mg/m2 in cohorts of three new patients. Radiation therapy was administered in three field technique over 6-7 weeks in 2.0 Gy/daily fractions for 5 consecutive days/week up to total doses of 60-70 Gy. RESULTS: From 1994-1996, 18 patients completing three dose levels were included into the study. Altogether, 101 courses of chemotherapy were evaluable for toxicity. On the second dose level (30 mg/m2) one of three patients experienced DLT with Grade IV mucositis. On the next dose level with 40 mg/m2 PAC weekly one patient experienced DLT being prolonged Grade III mucositis. From the following three patients required, two patients showed no DLT. The third patient showed mucositis of WHO Grade 4 and died from hemorrhage caused by a rupture of the a pharyngeal wall. Dose level 2 (30 mg/m2) was repeated and one of the three newly treated patients again suffered from mucositis WHO Grade 4. CONCLUSION: When PAC is given weekly as a 1-h infusion concomitant to radiotherapy, MTD is 30 mg/m2 with mucositis being DLT; hematological and further nonhematological toxicity is mild.     

Structural changes in membranes of proliferating leukocytes L-41 as affected by low doses of ionizing radiation

The dose-dependent effects of gamma-radiation on the leucocyte cultures L-41 has been investigated. Irradiation by the dose of 0.25 Gy stimulates the cell proliferation while that by the doses of 1.0 and 2.0 Gy inhibits this process. In this dose range the radiohormesis effects characterizing structural organization of the probed membranes have been also registered for fluorescence parameters. The zone of qualitative transition of response of the cell membranes to radiation is individual for various effects. The action of radiation in the doses of 0.25 and 0.50 Gy induces a decrease of ANS fluorescence intensity and a decrease of membrane protein immersion in the lipid bilayer of leukocyte membranes. The values of these parameters rise at the doses of 1.0 and 2.0 Gy that reflects different directions of structural changes in various membrane regions. The irradiation in the range of 0.25-1.0 Gy induces the increase of microviscosity in deep regions of membrane lipid matrix while at the dose 2.0 Gy it causes its decrease. Radioactive radiation does not change the membrane protein conformation of leukocytes and polarity of lipid bilayer hydrophobic zones as recorded by fluorescent methods used.     

Prevention of radiation induced taste aversion in rats

Diltiazem, a calcium channel blocker, and a cardiovascular therapeutic agent offers significant protection to mice against lethal dose of ionizing radiation. Considering the potential efficacy of diltiazem as a radioprotector for human use, it was deemed necessary to investigate its influence on radiation-induced behavioural changes like nausea, vomiting, learning, memory and performance. In the present studies, conditioned taste aversion (CTA) test based on consumption of saccharin solution, was used as a marker of behavioural changes. Significant CTA (97 +/- 2%) was observed in rats irradiated with Co-60 gamma rays (absorbed dose 1 Gy). Administration of diltiazem at doses greater than 10 mg/kg, body wt, evoked CTA in a dose-dependent manner and that was found to be further aggravated on irradiation. At a lower dose of 5 mg/kg, body wt, diltiazem did not evoke CTA and protected against radiation induced aversion significantly (62 +/- 3%). The results suggest that diltiazem at concentrations lower than 10 mg/kg, body wt, in rats may be useful in preventing radiation induced behavioural changes. This observation could be of particular significance in clinical radiotherapy where radiation induced nausea and vomiting are of great concern.     

Cloning and analysis of the human complement factor H gene promoter

The compound WR 238605 is a primaquine analog being developed by the U.S. Army as an antimalarial drug. Currently, there is no established treatment for Plasmodium vivax parasitemias that are not cured by chloroquine. This study tested WR 238605, chloroquine, and their combinations against a chloroquine-resistant strain of P. vivax (AMRU 1) in Aotus monkeys. A total dose of 3 mg/kg of WR 238605 given at a dosage of 1 mg/kg/day for three days cleared patent parasites in all eight monkeys but recrudescence of parasitemia occurred 15-25 days after initiation of treatment. A total dose of 9 mg/kg of WR 238605 over a three-day period cured all three monkeys of their infections. A total dose of 30 mg/kg of chloroquine did not clear patent infections in three monkeys, whereas a total dose of 60 mg/kg generally (two of three) cleared patent parasitemia but did not cure. Whereas total doses of 30 mg/kg of chloroquine or 3 mg/kg of WR 238605 given alone failed to cure, both drugs given in combination at these dosages cured two of three infections. These results indicate that WR 238605 may be an alternative treatment for chloroquine-resistant vivax malaria.     

Paclitaxel enhances in vitro radiosensitivity of squamous carcinoma cell lines of the head and neck

Squamous cell carcinoma of the head and neck is the fourth most common cancer in the United States, and therapy for very advanced cases is relatively ineffective. Paclitaxel has activity against cancers of the breast, lung, prostate, cervix, and ovary. The activity of paclitaxel for squamous cell carcinoma of the head and neck is less certain, and results of its radiosensitization properties have been variable. The radiation responses of two squamous carcinomas, SCC-9 (oropharynx) and HEP-2 (larynx), were examined to determine the radiosensitizing potential of paclitaxel. In vitro exposures for 24 and 48 h with paclitaxel concentrations of 10(-4) to 6 x 10(-2) microg/ml were followed by irradiation of 0.1-10 Gy. Percent survival was calculated by colony count, and the paclitaxel-radiation interaction was quantitated by the median effect principle and the combination index method of Chou and Talalay. The paclitaxel-radiation combination resulted in multiphasic interactions in both 24 and 48 h paclitaxel pretreatment in SCC-9 and HEP-2 cell lines. In general there was slight synergism [combination index (CI) <1] at low dose-low effect levels (e.g., at a paclitaxel concentration of 0.002 microg/ml or lower and radiation of 0.1-0.3 Gy), moderate antagonism (CI >1) at median dose ranges and strong synergism (CI <1) at high dose ranges (e.g., at a paclitaxel concentration of 0.012-0.06 microg/ml and radiation doses of 3-10 Gy), especially at a surviving fraction of <0.1, which is therapeutically relevant. The median effect principle and combination index method provided a simple way to quantitate the synergism or antagonism of a paclitaxel-radiation interaction under various conditions. This analysis demonstrated that paclitaxel-radiation synergy exists at doses that are readily achievable in the clinical scenario for both agents and that greater synergy occurred at high dose-high effect levels. These results suggest that the combination of both therapies should be explored further in clinical trials assessing the treatment of squamous cell carcinomas of the head and neck.     

Effect of radiation therapy on small-cell lung cancer is reduced by ubiquinone intake

The effect of oral ubiquinone (Q10) intake on the in vivo response of tumors to single dose radiotherapy was examined. The human small-cell lung cancer (SCLC) line CPH 054A, which is sensitive to relatively low doses of X-radiation, was grown as subcutaneous transplants in the flanks of nude nu/nu mice. When macroscopical growth was established, groups of mice received either 10, 20 or 40 mg/kg Q10 in 30 mL soy oil intragastrically daily on 4 consecutive days. Controls received either 30 mL of pure soy oil or nothing. Three h after the last dose half of the tumors in each group received a single radiation dose of 5 Gy, using a 300 kV therapeutic unit. The macroscopic growth pre- and posttreatment was analyzed according to a transformed Gompertz algorithm using the software program GROWTH. Treatment with Q10 or soy oil alone had no effect on tumor growth compared with untreated controls. Groups of tumors that received Q10 and radiotherapy had a significantly lower specific growth delay (SGD) than the radiotherapy-only groups. This effect was significant at 40 mg/kg and borderline at 20 mg/kg, whereas at 10 mg/kg no radioprotection was seen. We conclude that systemic Q10 reduces the response to single dose tumor irradiation inxenotransplanted human SCLC tumors.     

Concurrent cisplatin, prolonged oral etoposide, and vincristine plus chest and brain irradiation for limited small cell lung cancer: a phase II study of the Southwest Oncology Group (SWOG-9229)

PURPOSE: The primary objectives of the study were to evaluate the efficacy and safety of prolonged oral (PO) etoposide as part of cisplatin-based chemotherapy plus concurrent chest/brain irradiation induction, followed by CAV consolidation, in the treatment of patients with limited-stage small cell lung cancer (SCLC-LD) within a cooperative group setting. METHODS AND MATERIALS: Fifty-six eligible patients with SCLC-LD received three 28-day cycles of cisplatin 50 mg/m2 i.v. (days 1, 8; 29, 36; and 57, 64), PO etoposide 50 mg/m2 (days 1-14, 29-42, and 57-70), and vincristine 2 mg i.v. (days 1, 29, and 57). Thoracic irradiation (TRT) was administered at 1.8 Gy in 25 daily fractions to a total dose of 45 Gy via an AP:PA arrangement, to begin concomitantly with induction chemotherapy. Prophylactic cranial irradiation (PCI) was started on day 15 of induction therapy. Fifteen daily fractions of 2.0 Gy were administered to the entire brain to a total dose of 30 Gy to finish at approximately the same time as TRT. Two 21-day cycles of consolidation cyclophosphamide 750 mg/m2 i.v., doxorubicin 50 mg/m2 i.v., and vincristine 2 mg i.v. (all on days 1 and 22), were given beginning on day 106 or week 16, from the start of induction therapy. RESULTS: Among 56 eligible patients, 93% had SWOG performance status 0-1. All had adequate organ function and had not received prior therapy. The overall confirmed response rate was 46%, including 16% complete responders and 30% partial responders. After a minimum follow-up duration of 17 months, the Kaplan-Meier median progression-free (PFS) and overall survival (OS) were 10 and 15 months, respectively. Two-year survival is 28%. Only 28 of 56 patients (50%) completed chemotherapy per protocol, while 52 of 56 patients (93%) completed radiation per protocol. Eleven patients (20%) discontinued secondary to toxicity and two patients died from treatment. The major toxicity was hematologic. The two deaths were secondary to infection. Of the nonhematologic toxicities, there were 10 cases of pulmonary fibrosis (including one Grade 3) and six cases of pneumonitis (including one Grade 3). CONCLUSION: Concomitant chemoradiation with oral etoposide as part of a platinum-based chemotherapy and TRT induction regimen is toxic. The CR rate is not better than our prior best group-wide experience. The progression-free and overall survival are similar to published trials utilizing short-course i.v. etoposide. As in chemotherapy for extensive-stage SCLC, there is no apparent advantage to prolonged exposure to etoposide, and toxicity resulted in an inferior therapeutic index compared to programs with shortened exposure.     

Endothelium-dependent blunted membrane potential responses to ATP-sensitive K+ channel modulators in aortae from rats with cirrhosis

Gemcitabine, 2'2'-difluoro-2'-deoxycytidine, is an inhibitor of DNA synthesis and has been shown previously in vitro and in vivo to enhance the cytotoxic activity of radiation as well as some chemotherapeutic agents. Because gemcitabine has shown clinical activity on its own in several solid tumors traditionally treated with radiotherapy, it was of interest to optimize the combination of gemcitabine and radiation. To determine the optimal gemcitabine dose to combine with irradiation and to determine the effect of gemcitabine on tumor growth, mice bearing SA-NH tumors were treated with 2.5 to 600 mg/kg gemcitabine, and subsequent tumor growth was determined. At low doses, gemcitabine induced transient growth delay, whereas higher doses showed both cytotoxic and cytostatic activity. Flow cytometric, histological, and mitotic analyses of irradiated tumors showed that gemcitabine induced a dose-dependent inhibition of DNA synthesis and induction of apoptosis of cells in S phase. DNA synthesis recovered in cells at the G1-S boundary of the cell cycle in a dose-dependent manner, and a parasynchronous movement of cells through the cell cycle ensued. To determine the optimal schedule for gemcitabine administration in relation to irradiation, tumor-bearing mice were given a single 50 mg/kg dose of gemcitabine at various times before or after irradiation. Gemcitabine enhanced radioresponse in a time-dependent fashion. The highest enhancement factors for tumor growth delay (1.68-2.03) were observed when gemcitabine was administered 24-60 h before irradiation. Although gemcitabine reduced the radiation tumor control dose at all administration times used, the greatest enhancement of tumor radiocurability occurred when gemcitabine was administered 24 h before irradiation (dose modification factor of 1.54). Moreover, gemcitabine decreased the lung metastatic rate in mice with local tumor control from 73% in mice receiving radiation alone to 40% in mice receiving the combination (all combination times included). These results suggest that gemcitabine has strong radioenhancing properties and that the greatest interaction occurs when gemcitabine administration precedes irradiation by 24-72 h. Preliminary studies indicate that normal tissues recover more quickly than tumor tissues from gemcitabine treatment; thus, optimized scheduling of gemcitabine and irradiation may serve to improve the therapeutic ratio of the combination.     

A quantitative assay for assessing allelic proportions by iterative gap ligation

PURPOSE: We compared gastrointestinal toxicity of single vs. fractionated total body irradiation (TBI) administered at dose rates ranging from 0.021 to 0.75 Gy/min in a canine model of marrow transplantation. METHODS AND MATERIALS: Dogs were given otherwise marrow-lethal single or fractionated TBI from dual 60Co sources at total doses ranging from 8-18 Gy and delivered at dose rates of 0.021, 0.05, 0.10, 0.20, 0.40, and 0.75 Gy/min, respectively. They were protected from marrow death by infusion of previously stored autologous marrow cells and they were given intensive supportive care posttransplant. The study endpoint was 10-day mortality from gastrointestinal toxicity. Logistic regression analyses were used to jointly evaluate the effects of dose rate, total dose, and delivery regimen on toxicity. RESULTS AND CONCLUSION: With increasing dose rates, mortality increased for either mode of delivery of TBI. With dose rates through 0.10 Gy/min, mortality among dogs given single vs. fractionated TBI appeared comparable. Beginning at 0.20 Gy/min, fractionation appeared protective for the gastrointestinal tract. Results in dogs given TBI at 0.40 and 0.75 Gy/min, respectively, were comparable, and dose fractionation permitted the administration of considerably higher total doses of TBI than were possible after single doses, an increment that was on the order of 4.00 Gy. The data indicate that the impact of fractionating the total dose at high dose rates differs from the effect of fractionation at low dose rates.     

Accelerated-interrupted radiation therapy given concurrently with chemotherapy for locally advanced non-small cell lung cancer

PURPOSE: To evaluate the efficacy of multidrug chemotherapy combined with accelerated radiation therapy in the treatment of localized but unresectable non-small cell lung cancer. PATIENTS AND METHODS: Between September 1990 and February 1993, 35 patients with Stage III (15 IIIA & 20 IIIB) non-small cell lung cancer were entered on a protocol using combined accelerated radiation therapy and chemotherapy. Radiation therapy consisted of 55.6 Gy in 30 fractions (1.8 Gy bid for 5 consecutive days given in 3 weeks [total of 15 days], every other week). Chemotherapy consisted of cisplatin (10 mg/m2), vinblastine (4 mg/m2), 6-thioguanine (40 mg bid), and 5-fluorouracil (400 mg/m2 as continuous infusion) given concomitantly with radiation therapy. Approximately 3 weeks following completion of radiation therapy, two cycles of consolidation chemotherapy were given, consisting of two doses of cisplatin (120 mg/m2) 4 weeks apart and six doses of vinblastine (4 mg/m2) given on two consecutive days every other week for 3 weeks. RESULTS: Six patients were still alive at last follow-up; for them the median follow-up time is 47 months (range, 39-55.8). The median survival time is 17.5 months. The 1-, 2-, 3- and 4.5-year survival rates are 69%, 37%, 20% and 17%, respectively. Overall response rate is 63%, with 51.5% partial response and 11.5% complete response rates. Esophagitis occurred as follows: Grade 4 = 0, Grade 3 = 1, Grade 2 = 6, and Grade 1 = 13. No patient developed Grade 3 or 4 acute respiratory toxicity. Significant hematologic toxicity occurred as follows: 37% Grade 3 and 31% Grade 4 leukopenia. Radiation pneumonitis occurred in two patients. DISCUSSION: The regimen tested in this protocol appears to be very well tolerated with minimal pulmonary or esophageal toxicity. This, coupled with the shortened course of radiation therapy and the ability to deliver the combined radiation and chemotherapy portion of the treatment on an outpatient basis most of the time, has made multi-modality treatment for this malignancy much easier and more convenient for patients. In addition, the favorable survival in this group of patients with locally advanced disease is very encouraging and warrants further study.     

Correlation of increased mortality with the suppression of radiation-inducible microsomal epoxide hydrolase and glutathione S-transferase gene expression by dexamethasone: effects on vitamin C and E-induced radioprotection

Previous studies in this laboratory have shown that gamma-ray ionizing radiation in combination with oltipraz, a radioprotective agent, enhances hepatic microsomal epoxide hydrolase (mEH) and glutathione S-transferase (GST) expression. The present study was designed to investigate the effects of dexamethasone on the radiation-inducible expression of mEH and rGST genes and on the vitamin C and E-induced radioprotective effects in association with the expression of the genes. Treatment of rats with a single dose of dexamethasone (0.01-1 mg/kg, p.o.) caused a dose-dependent decrease in the constitutive mEH gene expression at 24 hr. The radiation-inducible mEH mRNA level (threefold increase after 3 Gy gamma-irradiation) was decreased by 21% and 88% by dexamethasone at the doses of 0.1 and 1 mg/kg, respectively. Although dexamethasone alone caused 2- to 5-fold increases in the hepatic rGSTA2 mRNA level, rats treated with dexamethasone prior to 3 Gy irradiation exhibited 80%-93% suppression in the radiation-inducible increases in the rGSTA2 mRNA level. The inducible rGSTA3 and rGSTA5 mRNA levels were also significantly decreased by dexamethasone, whereas the rGSTM1 mRNA level was reduced to a lesser extent. Vitamin C and/or E, however, failed to enhance the radiation-inducible increases in hepatic mEH and rGST mRNA levels. Whereas rats exposed to 3 Gy irradiation with or without vitamin C treatment (30 or 200 mg/kg/day, p.o., 2 days) exhibited approximately threefold increases in the mEH and rGSTA2/3/5 mRNA levels relative to untreated animals, dexamethasone treatment (1 mg/kg, p.o.) resulted in 64%-96% decreases in the mRNA levels at 24 hr. The inducible rGSTM1/2 mRNA levels in the vitamin C/E-treated rats were approximately 50% suppressed by dexamethasone. Although vitamin C and/or E treatment (200 mg/kg/day, p.o., 2 days) improved the 30-day survival rates of the 8 Gy gamma-irradiated mice from 39% up to 74%, the improved survival rate of gamma-irradiated animals was reduced to 30% by dexamethasone pretreatment (1 mg/kg/day, 2 days). The mean survival time of dexamethasone-treated animals was reduced to approximately 2 days from 14 days in the animals with total body irradiation alone. No significant hematologic changes were observed in mice at 10 days after dexamethasone plus gamma-irradiation, as compared with irradiation alone. These results demonstrate that: dexamethasone substantially suppresses radiation-inducible mEH, rGSTA and rGSTM expression in the liver; vitamins C/E exhibit radioprotective effects without enhancing radiation-inducible mEH and GST gene expression; and inhibition of radiation-inducible mEH and rGST gene expression in the vitamin C- and E-treated animals by dexamethasone was highly correlated with reduction in the survival rate and the mean survival time of gamma-irradiated animals.