Biomedical subjects

T S Herman

Publications and source records attributed to T S Herman.

At least 73 records · Page 4Linked to original sources

PubMed1990

Interaction of platinum complexes of thiazin and xanthene dyes with hyperthermia.

In an attempt to develop platinum-containing drugs for use with hyperthermia that would be relatively nontoxic at 37 degrees C but would become very cytotoxic at 42 degrees or 43 degrees C, several nuclear dyes were complexed to the tetrachloroplatinum(II) dianion (PtCl4) at a ratio of 2:1. The cytotoxicity of PtCl4 complexes of three thiazin dyes (thionin, azure B, and methylene blue), the xanthene dye pyronin Y, and the thiazole dye thioflavin was examined in exponentially growing euoxic and hypoxic EMT6 cells in vitro at 37 degrees, 42 degrees, and 43 degrees C and at pH 7.40 and 6.45. Of the thiazin dye complexes, the cytotoxicity of Pt(methylene blue)2 was most enhanced at hyperthermic temperatures. Both Pt(pyronin Y)2 and Pt(thioflavin)2 also became markedly more cytotoxic at 42 degrees and 43 degrees C at pH 6.45 vs pH 7.40. In vivo tumor excision assays in the FSaIIC fibrosarcoma showed that with each of the thiazin dye-platinum complexes, hyperthermia enhanced cell kill [most effectively on Pt(methylene blue)2] but was not dose-modifying. For both Pt(pyronin Y)2 and Pt(thioflavin)2, however, administration of 43 degrees C, 30-min hyperthermia to the tumor immediately after i.p. drug injection was dose-modifying. Tumor growth delay studies in the FSaIIC tumor system demonstrated that, as with the in vitro studies, Pt(pyronin Y)2 and Pt(methylene blue)2 were most enhanced by hyperthermia [tumor growth delay increased by 4.8- and 3.0-fold, respectively, vs only 1.3-fold for cisplatin (CDDP)]. Examination of intracellular platinum levels after exposure of EMT6 cells to 25 microM of drug for 1 h at 37 degrees and 42 degrees C and at pH 7.40 and 6.45 showed that each platinum-dye complex achieved platinum levels that were 100-600 times higher at 37 degrees C and pH 7.40 than those obtained using CDDP. The platinum levels for each drug dropped markedly when exposure took place at pH 6.45. Exposure at 42 degrees C only moderately increased platinum levels in cells exposed to these drugs. Thus, for several of these drugs the level of cytotoxicity observed was in great part independent of the intracellular platinum levels achieved. Pt(pyronin Y)2 is an effective drug for use with hyperthermia, and further studies using this combination with and without radiation are under way.

Animals↗

PubMed1990

Addition of a hypoxic cell selective cytotoxic agent (mitomycin C or porfiromycin) to Fluosol-DA/carbogen/radiation.

In an effort to develop effective combination treatments for use with radiation against solid tumors, the cytotoxic effects of the addition of mitomycin C or porfiromycin on treatment with Fluosol-DA/carbogen (95% O2/5% CO2) breathing and radiation in the FSaIIC tumor system were studied. In vitro mitomycin C and porfiromycin were both preferentially cytotoxic toward hypoxic FSaIIC cells. After in vivo exposure, however, the cytotoxicity of mitomycin C toward single cell tumor suspensions obtained from whole tumors was exponential over the dose range studied, but for porfiromycin a plateau in cell killing was observed. With Fluosol-DA/carbogen breathing and single dose radiation, addition of either mitomycin C or porfiromycin increased the tumor cell kill achieved at 5 Gy by approximately 1.2 and 1.0 logs, respectively. Less effect was seen with addition of the drugs at the 10 and 15 Gy radiation doses. In tumor growth delay experiments, the addition of either mitomycin C or porfiromycin to Fluosol-DA/carbogen breathing and radiation resulted in primarily an additive increase in tumor growth delay. The survival of Hoechst 33342 dye-selected tumor cell subpopulations indicated that Fluosol-DA/carbogen breathing increased the cytotoxicity of radiation (10 Gy) more in the bright cell subpopulation (4-fold) than in the dim cell subpopulation (2-fold) resulting in an overall 4-fold sparing of the dim subpopulation. Mitomycin C and porfiromycin were both more toxic toward the dim cell subpopulations. Addition of mitomycin C or porfiromycin to Fluosol-DA/carbogen breathing and radiation (10 Gy) resulted in a primarily additive effect of the drugs and radiation killing in both tumor cell subpopulations. Thus, with mitomycin C/Fluosol-DA/carbogen and radiation there was a 2-fold sparing of dim cells and with porfiromycin in the combined treatment a 1.6-fold sparing of the dim cell population. Our results indicate that treatment strategies directed against both oxic and hypoxic tumor subpopulations can markedly increase the tumor cell kill achieved by radiation.

Animals↗

PubMed1990

Influence of scheduling, dose, and volume of administration of a perfluorochemical emulsion on tumor response to radiation therapy.

Studies were carried out with a new, concentrated perfluorochemical emulsion (PFCE) of the perfluorochemical F44E (48% V/V). When given at 4, 1.6, or 1 g/kg in undiluted injection volumes iv 1 hr prior to a range of single doses of radiation with inspired carbogen dose modifying factors (DMF's) based on tumor growth delay (TGD) in the Lewis lung tumor of 2.5, 1.7, and 1.5, respectively, were produced. When the PFC dose was administered in a volume of 0.2 ml, the dose modifying factors produced by 4 g/kg (0.1 ml undiluted) did not change significantly (2.6), but the dose modifying factors produced by 1.6 g/kg (0.04 ml undiluted) and by 1.0 g/kg (0.025 ml undiluted) increased significantly to 2.0 and 1.8 (p less than 0.05), respectively. Using the tumor excision assay at 24 hr post treatment in the FSaIIC fibrosarcoma, administration of 6, 4, or 2 g/kg in 0.2 ml injections plus carbogen breathing 1 hr prior to and during treatment resulted in dose modifying factors of 1.5, 1.6, and 1.3, respectively. In a fractionated radiation protocol in the Lewis lung tumor using four daily fractions, a dose of 4 g/kg of PFC on days 1 and 3 proved superior to a dose of 2 g/kg daily (dose modifying factors 2.4 vs. 1.9, p less than 0.05). When a fractionated radiation regimen of 3 Gy daily X 5 and carbogen was used, PFC doses of 0.5, 1, 2, and 4 g/kg administered undiluted produced increasing tumor growth delays with increasing dose of PFCE and increasing frequency of administration. In addition, dilutions to 0.2 ml proved significantly more effective. In a 2-week fractionated radiation protocol using 2, 3, or 4 Gy daily X 5 weekly, PFCE given in 0.2 ml volume plus carbogen breathing daily at 4, 1.6, or 1 g/kg produced dose modifying factors of 2.0, 1.9, and 1.6, respectively. Finally, when used in a day 1, 3, and 5 radiation regimen for 3 weeks at 2, 3, or 4 Gy/fraction, 4 g/kg of PFCE given in a volume of 0.2 ml plus carbogen breathing produced a superior dose modifying factor (1.6) as compared with 1.6 or 1.0 g/kg (dose modifying factors 1.4 and 1.3, respectively). These results indicate that PFCE plus carbogen breathing effectively enhances the antitumor effects of both single dose and fractionated radiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Trimodality therapy (drug/hyperthermia/radiation) with BCNU or mitomycin C.

To develop multimodality treatment combinations with high curative potential in advanced local disease, BCNU (N,N'-bis(2-chloroethyl)-N-nitro-sourea) and mitomycin C were tested with hyperthermia and radiation in the FSaIIC fibrosarcoma system. Growth delay experiments demonstrated that, while neither BCNU nor mitomycin C produced dose modification of the radiation response, and hyperthermia (43 degrees C, 30 min) produced only a moderate dose modification (1.4 +/- 0.2), the combination of BCNU plus hyperthermia resulted in a radiation dose modifying factor (DMF) of 1.9 +/- 0.3, and mitomycin C plus hyperthermia a dose modifying factor of 2.1 +/- 0.4. Tumor cell survival over a range of BCNU doses administered i.p. immediately before hyperthermia resulted in a dose modifying factor of 1.8 +/- 0.2 versus drug alone. With mitomycin C however, giving the drug immediately prior to heating produced a dose modifying factor due to hyperthermia of only 1.2 +/- 0.10. Hoechst 33342 diffusion was used to separate tumor cells into predominately oxic and hypoxic subpopulations. Administration of the single, double and trimodality therapies showed that BCNU was 3.1-fold more toxic to the oxic versus the hypoxic cells whereas mitomycin C was 3.5-fold more toxic to the hypoxic compared to the oxic cells. Hyperthermia was 1.4-fold more toxic to the hypoxic versus the oxic cells whereas 10 Gy of radiation was 2.0-fold more toxic to the oxic compared to the hypoxic cells. The combination of hyperthermia plus radiation increased killing in both Hoechst dye defined subpopulations but relatively more in the hypoxic cells in which killing was 1.8-fold greater than in the oxic cells. When heat was delivered immediately after i.p. administration of the anticancer drugs, hyperthermia increased BCNU killing in the oxic cells by 17.2-fold versus 4.4-fold in the hypoxic cells and increased mitomycin-killing by 2.6-fold in the oxic cells versus 17-fold in the hypoxic cells. Use of the full trimodality treatment, given in the sequence drug (BCNU, 50 mg/kg or mitomycin-C 5 mg/kg)----heat (43 degrees C, 30 min)----radiation (10 Gy) produced a 3 log kill in the oxic cells versus a 2 log kill in the hypoxic cells with BCNU and a 2 log kill in the oxic cells versus a 3 log kill in the hypoxic cells with mitomycin C. These results indicate that the use of selected anticancer drugs with hyperthermia and radiation can produce highly cytotoxic interactions which markedly modify the effect of radiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

The interaction of cisplatin plus etoposide with radiation +/- hyperthermia.

The addition of concurrent etoposide and cisplatin to radiation +/- hyperthermia was evaluated in the murine FSaIIC fibrosarcoma tumor system. Tumor growth delay (TGD) demonstrated that when the drugs were tested with radiation (3 Gy daily X 5) plus (43 degrees X 30 min) local hyperthermia, cisplatin/hyperthermia/radiation (TGD approximately 25 days) was significantly more effective than etoposide/hyperthermia/radiation (TGD approximately 14 days). The addition of etoposide to cisplatin/hyperthermia/radiation, however, yielded a significantly longer growth delay (approximately 34 days). Tumor cell survival studies demonstrated that hyperthermia (43 degrees C, 30 minutes) was dose modifying for etoposide cytotoxicity (dose modifying factor approximately 2.0 as determined by comparisons of the slopes of the curves). The addition of etoposide to cisplatin modified cisplatin killing only slightly at 37 degrees C or 43 degrees C. Considerable additional cell kill was observed over a range of radiation doses with cisplatin, hyperthermia, and etoposide added singly or in combination, especially at the lowest radiation dose tested (5 Gy), but essentially no dose modification was observed. Evaluation of Hoechst 33342 dye-selected tumor subpopulations demonstrated that cisplatin, etoposide, radiation (10 Gy), etoposide plus radiation, and cisplatin plus radiation killed significantly fewer dim (presumably hypoxic) cells than bright (presumably normally oxygenated) cells. Hyperthermia killed more dim than bright cells. The combination of hyperthermia with cisplatin and radiation, however, resulted in approximately 5-fold lesser kill in dim cells, and the addition of etoposide increased this differential to 6.4-fold. These results indicate that etoposide adds small but measurable antitumor effects when used with cisplatin alone or with cisplatin in combination with radiation +/- hyperthermia (especially at lower radiation fraction sizes).

Animals↗

PubMed1990

1,2-dithiol-3-thione and dithioester analogues: potential radioprotectors.

Several 1,2-dithiol-3-thione and dithioester compounds were assayed for radioprotective capabilities in EMT6 cells in vitro. The 1,2-dithiol-3-thiones were generally more cytotoxic than the dithioesters and in some instances were more cytotoxic toward hypoxic cells than toward normally oxygenated cells. When the drugs were present at a concentration of 500 microM for 1 h prior to and during radiation delivery, the 5-(2-thienyl)-1,2-dithiol-3-thione produced a radiation protection factor (RPF) of 2.7 at 1 log of cell kill. The 4-methyl analogue of this same compound was, however, much less effective, producing a RPF of only 1.2. The 4-ethoxycarbonyl analogue was moderately active, producing a RPF of 1.7. The 4-methyl-5-(2-pyrazinyl)-1,2-dithiol-3-thione (Oltipraz) was least effective, yielding a RPF of only 1.1. Of the dithioesters tested, methyl 3-pyrrolidino-2-phenylpropene dithiocarboxylate produced a RPF of 2.6, methyl 3-piperidino-2-phenylpropenedithiocarboxylate a RPF of 2.7, and the corresponding 3-morpholino and 3-thiomorpholino derivatives RPF values of 2.7 and 2.9, respectively. The iodide salt of 4-ethoxycarbonyl-5-(2-thienyl)-1,2-dithiol-3-thione produced a RPF of 2.6 Methyl 3-cyclohexylamino-2-phenylpropenedithiocarboxylate was equally effective (RPF = 2.6). Finally, methyl 3-morpholino-3-thienyl-2-methylpropenedithiocarboxylate and methyl 3-morpholino-3-(2-pyrazinyl)-2-methylpropenedithiocarboxylate were less effective, producing RPF values of 2.0 and 1.6, respectively. These results demonstrate that several of these compounds are highly effective radioprotectors. In vitro and in vivo studies testing their efficacy are underway.

Animals↗

PubMed1990

Gallium-67 imaging: a predictor of residual tumor viability and clinical outcome in patients with diffuse large-cell lymphoma.

Durable complete remissions (CRs) can be achieved in patients with diffuse large-cell lymphoma (DLCL) with multidrug chemotherapy. The length of time to reach CR may be predictive of treatment outcome. However, defining CR by chest radiograph or computed tomography (CT) is often difficult since residual abnormalities do not always indicate residual disease. We have prospectively evaluated the ability of gallium-67 citrate (Ga-67) imaging to define residual disease and predict outcome in 37 consecutive patients with DLCL. Patients received 296 to 370 megabecquerels (MBq) Ga-67 and were imaged prior to, following cycles 4 to 6, and at completion of intensive chemotherapy. Ga-67 scan results were correlated with radiographic studies. Seventeen of 37 patients (46%) showed persistent, abnormal Ga-67 uptake halfway through chemotherapy. Of these, four were in CR, 11 were in partial remission (PR), and two showed no change in tumor size. At follow-up, 10 (59%) have died (three who were scored as CR and seven who were in PR halfway through therapy), two are alive with active tumor, one relapsed and survives following bone marrow transplant, and four (three in PR and one in CR at the therapeutic halfway point) are without disease at a median of 28 months from presentation. Of the 20 patients who were Ga-67-negative halfway through therapy, 11 were in CR and nine were in PR. Five of 20 patients (25%) have died. Three, in radiographic CR died at 11, 26, and 28 months, and two in radiographic PR died at 15 and 17 months. One patient is alive with active tumor, and 14 patients (70%) are alive without disease at a median of 34 months from presentation. Ga-67 imaging proved to be an excellent indicator of residual viable tumor; a positive scan halfway through therapy predicted for a poor outcome and may well justify a change in treatment.

Adult↗

PubMed1990

Preclinical studies relating to the use of thiotepa in the high-dose setting alone and in combination.

In vitro and in vivo studies with N,N',N''-triethylene-thiophosphoramide (thiotepa) alone and in combination with cyclophosphamide (CTX) were carried out using the MCF-7 human breast carcinoma cell line and the EMT6 mouse mammary carcinoma cell line. In vitro, survival curves were essentially linear. The cytotoxicity of thiotepa toward MCF-7 cells was markedly dependent on the presence of oxygen during the period of drug exposure, with a 3-log greater cell kill at 500 mumol with cells that were normally oxygenated compared with hypoxic cells. Incubation of thiotepa with an Aroclor 1254-induced rat liver S-9 homogenate in the presence of a reduced nicotinamide adenine dinucleotide phosphate-regenerating system resulted in an eightfold increase in cytotoxicity toward the MCF-7 cells over a wide range of drug concentrations. The thiotepa metabolite N,N',N''-triethylenephosphoramide (TEPA) was significantly less cytotoxic toward the MCF-7 cells than was thiotepa. Simultaneous and immediately sequential treatments with thiotepa and CTX produced supra-additive cell killing of both cell lines, although the magnitude of the supra-additivity was greater in the MCF-7 cell line than in the EMT6 cell line. These drugs Vppeared to be equally effective as thiol-depleting agents. By DNA alkaline elution, there was a pattern of increasing DNA cross-linking similar to the increasing levels of cytotoxicity of this drug combination as the concentrations of thiotepa increased. In the EMT6 tumor in vivo, the maximally tolerated combination therapy (5 mg/kg x 6, thiotepa, and 100 mg/kg x 3, CTX) produced about 25 days of tumor growth delay, which was not significantly different than expected for additivity of the individual drugs. The survival of EMT6 tumor cells after treatment of the animals with the various single doses of thiotepa and CTX was assayed. Tumor cell killing by thiotepa produced a very steep, linear survival curve through 5 logs with increasing dose. The tumor cell survival cure for CTX to 500 mg/kg had linear tumor cell kill through almost 4 logs. In vivo modeling of quasicontinuous exposure (3 intraperitoneal over 9 hours) versus pulse (single-dose) administration of thiotepa and CTX compared EMT6 tumor cell survival with survival of bone marrow as a representative sensitive normal tissue. With CTX, there was a considerable increase in the therapeutic index (killing of tumor cells/killing of colony forming units-granulocyte macrophage) when the same total dose of drug was administered in multiple injections versus a single injection. For thiotepa, smaller increases in therapeutic index were also observed with the multiple-injection schedule.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1990

Effect of acidic pH on radiosensitization of FSaIIC cells in vitro by misonidazole, etanidazole, or cis-diamminedichloroplatinum (II).

Because acidic regions may coexist with hypoxic regions in solid tumors, we have studied the effect of acidic extracellular pH on the abilities of misonidazole, etanidazole, and cis-diaminedichloroplatinum(II) (CDDP) to radiosensitize hypoxic FSaIIC cells in vitro. For 1-h exposures to misonidazole prior to and during irradiation, the sensitizer enhancement ratios (SERs) were 2.10 +/- 0.18 at 1 mM drug and 2.50 +/- 0.16 at 5 mM drug at pH 7.40 but only 1.90 +/- 0.14 and 2.30 +/- 0.14, respectively, at pH 6.45. For etanidazole the SERs at pH 7.40 at 1 and 5 mM drug were 1.90 +/- 0.13 and 2.40 +/- 0.18, respectively, but only 1.25 +/- 0.13 and 1.70 +/- 0.17, respectively, at pH 6.45. The decrease in the SERs for both 2-nitroimidazole compounds was statistically significant (P less than 0.01). When CDDP at concentrations of 1 and 5 microM was tested, SERs of 1.30 +/- 0.15 and 1.60 +/- 0.18, respectively, were observed at pH 7.40, and the increase was not significant at pH 6.45 (1.35 +/- 0.15 and 1.80 +/- 0.19, respectively). The cellular levels of misonidazole, etanidazole, and CDDP did not vary significantly at the environmental conditions tested. These results demonstrate that pH is a potentially important variable in the action of hypoxic cell radiosensitizing drugs and suggest that future evaluations of such agents should test the effects of pH.

Animals↗

PubMed1990

Cytotoxicity, radiosensitization, and DNA interaction of platinum complexes of thiazin and xanthene dyes.

Complexes of the platinum(II) tetrachlorodianion with positively charged nuclear dyes have been prepared in an effort to produce neutral molecules which could gain ready access to the nuclear DNA where the platinum(II) tetrachlorodianion could function as a radiosensitizing and a bifunctional alkylating agent. The thiazin dyes Thionin, Azure B, and Methylene Blue, the aminoxanthene dye Pyronin Y, and the thiazole dye Thioflavin have each been complexed to the platinum(II) tetrachlorodianion(PtCl4) in a ratio of 2:1(dye:PtCl4). Studies of the interaction of these complexes and of the dyes with the pBR322 plasmid superhelical DNA demonstrated that while each complex and dye readily associated with the DNA in a dose-dependent manner, only Pt(Thioflavin)2 and Thioflavin produced irreversible DNA changes (single-strand breaks). In exponentially growing EMT6 cells the cytotoxicity of these drugs was assessed in normally oxygenated and hypoxic cells at both pH 7.4 and 6.45. At concentrations ranging from 1 to 500 microM, Pt(Methylene Blue)2 was significantly more cytotoxic than the other thiazin dye complexes Pt(Thionin)2 and Pt(Azure B)2. The cytotoxicity of Pt(Thionin)2 and Pt(Methylene Blue)2 was increased in normally oxygenated and hypoxic cells at low pH. Both Pt(Pyronin Y)2 and Pt(Thioflavin)2 were more toxic than the thiazin complexes. Pt(Pyronin Y)2 was most cytotoxic to normally oxygenated cells at normal pH and hypoxic cells at low pH, while Pt(Thioflavin)2 was most cytotoxic to cells at low pH under both oxygenation conditions. In vitro studies of the radiosensitizing properties of these agents in EMT6 cells demonstrated that exposure to 100 microM for 1 h before and during irradiation (except for Pt[Thioflavin]2, which was assayed at 25 microM) resulted in enhancement rations of 2.5, 1.9, 1.5, and 1.5 for Pt(Azure B)2, Pt(Thionin)2, Pt(Pyronin Y)2, and Pt(Thioflavin)2, respectively, in hypoxic cells. In contrast, Pt(Methylene Blue)2 (and Methylene Blue) proved to be a radioprotector of normally oxygenated cells and did not sensitize hypoxic cells to the cytotoxic effects of radiation. In the FSaIIC fibrosarcoma in vivo administration of each drug at 100 mg/kg intraperitoneally (ip) 15 min prior to irradiation (except for Pt[Thioflavin]2, which was given at 1 mg/kg ip) showed that, with single radiation fractions of 10 and 20 Gy, dose-modifying factors of 2.1, 1.8, 1.5, and 1.2 were produced by Pt(Azure B)2, Pt(Thionin)2, Pt(Pyronin Y), and Pt(Methylene Blue)2, respectively, after correcting for growth delays induced by the drug alone. In comparison, misonidazole at 1 g/kg ip produced a dose-modifying factor of 1.4.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Interaction of PtCl4(Fast Black)2 with hyperthermia.

We are developing complexes of negatively charged PtCl4 with positively charged nuclear dyes as new antitumor agents for use alone and in conjunction with hyperthermia and/or radiation. Elemental analysis has shown that the complex PtCl4(Fast Black)2 is a tight ion pair. In experimentally growing EMT6 cells in vitro, PtCl4(Fast Black)2 killed cells in a log-linear manner which increased as the temperature of the exposures was increased from 37 to 42 degrees C or 43 degrees C. In addition, cell kill was also increased under conditions of low pH (6.45), especially in hypoxic cells treated at elevated temperature. Measurement of intracellular platinum levels after exposure to 25 microM cisplatin or PtCl4(Fast Black)2 demonstrated that platinum levels were between 170- and 200-fold higher after exposure to PtCl4(Fast Black)2. In vivo studies in the FSaIIC murine fibrosarcoma showed, again, that PtCl4(Fast Black)2 killed in a log-linear manner. Treatment of tumors placed in the thigh with 43 degrees C, 30-min hyperthermia immediately following i.p. injection of PtCl4(Fast Black)2 was dose modifying. One hundred mg/kg of PtCl4(Fast Black)2 produced a 4.6-day tumor growth delay which increased to 6.4 days with 43 degrees C, 30-min hyperthermia immediately following i.p. injection of PtCl4(Fast Black)2 was does modifying. One hundred mg/kg of PtCl4(Fast Black)2 produced a 4.6-day tumor growth delay which increased to 6.4 days with 43 degrees C, 30-min hyperthermia (growth delay for hyperthermia alone was 1.4 days), and 500 mg/kg produced a 5.6-day delay which increased to 11.0 days with hyperthermia. In contrast, cisplatin (5 mg/kg) produced a 4.4-day delay which increased to 5.9 days with hyperthermia. PtCl4(Fast Black)2 was well tolerated by animals, and the maximally tolerated dose was approximately 650 mg/kg. This new complex appears quite active as an antitumor agent alone and in conjunction with hyperthermia, and, since other studies have shown it to interact positively with radiation, this agent seems a very appropriate candidate for further development as a clinical anticancer drug.

Animals↗

PubMed1989

Addition of misonidazole, etanidazole, or hyperthermia to treatment with fluosol-DA/carbogen/radiation.

The antitumor efficacy of adding the nitroimidazole radiosensitizing drugs misonidazole and etanidazole or hyperthermia (43 degrees C for 30 min) to Fluosol-DA/carbogen (95% O2/5% CO2) and irradiation was tested in the FSaIIC tumor system. Both the nitroimidazole drugs and hyperthermia produced additional tumor growth delays and tumor cell cytotoxicity when given with Fluosol-DA/carbogen, either before or after irradiation. For each of the modalities tested, the dose-modifying effect was greater when that therapy preceded rather than followed irradiation (misonidazole 2.7 vs. 1.9, etanidazole 2.4 vs. 1.7, hyperthermia 4.0 vs. 1.7 relative to the effect of radiotherapy alone). Because the nitroimidazole drugs must be present before radiation is administered to exert their radiosensitizing effect, the increase in tumor growth delay observed when these drugs cytotoxic to hypoxic cells were administered following Fluosol-DA/carbogen and irradiation suggests that Fluosol-DA/carbogen could not fully oxygenate the tumors and that the nitroimidazole drugs were effectively toxic to residual hypoxic cells. The treatment Fluosol-DA/carbogen----hyperthermia----irradiation produced a marked increase in tumor growth delay not seen with the sequence Fluosol-DA/carbogen----irradiation----hyperthermia. The results indicate that a treatment combination of radiation sensitizers may be more effective than irradiation plus Fluosol-DA with oxygen breathing alone.

Animals↗

PubMed1989

Interaction of hyperthermia and radiation in murine cells: hypoxia and acidosis in vitro, tumor subpopulations in vivo.

To better understand the effect of the level of oxygenation and pH on the heat-radiation interaction, these factors were modeled in vitro using FSaIIC cells in monolayer and correlated with the response of Hoechst 33342 dye-defined FSaIIC tumor subpopulations treated in vivo. Exposure to both 42 degrees C and 43 degrees C for 1 h in culture prior to graded single fractions of radiation resulted in a striking decrease in the radiation oxygen enhancement ratio which was pH as well as temperature dependent. The oxygen enhancement ratio at 37 degrees C and pH 7.40 (or pH 6.45) was 2.9, but decreased to 1.4 at 42 degrees C at normal pH, 1.2 at low pH, and 1.0 at 43 degrees C at both pH values tested. This decrease in the oxygen enhancement ratio resulted from a far more marked decrease in Do values for the radiation survival curves of hypoxic cells compared to normally oxygenated cells at elevated temperatures. In addition, the shoulder region of the radiation survival curves was significantly decreased with increasing temperatures and the magnitude of the decrease was greatest in hypoxic cells at low pH. In vivo treatment followed by immediate tumor excision showed that bright cells (presumably oxygenated cells at normal pH) were approximately 2-fold more sensitive to 10 Gy of radiation than were dim cells (presumably hypoxic cells at low pH) but that dim cells were 2.5-fold more sensitive to 43 degrees C for 30 min hyperthermia. The combination of hyperthermia followed by radiation proved to be 1.8-fold more toxic to dim than to bright cells. Both hyperthermia alone and hyperthermia plus radiation, in contrast to radiation alone, were significantly more cytotoxic when tumors were left in situ for 24 h prior to excision as compared with immediate excision. These results indicate that hyperthermia markedly sensitizes hypoxic cells at low pH to the cytotoxic effects of radiation, as well as effectively killing cells in this tumor subpopulation.

Acidosis↗

PubMed1989

Optimization of perfluorochemical levels with radiation therapy in mice.

We have examined the effects of a wide range of levels of Therox, a perfluorochemical emulsion containing bis-perfluorobutyl ethylene (F44E) with carbogen breathing on the tumor growth delay of the Lewis lung carcinoma produced by single dose radiation and fractionated radiation. The enhancement in tumor growth delay with single dose radiation therapy increased as the dose of F44E was increased from 1.2 g/kg (0.03 ml) to 4 g/kg (0.1 ml). As the dose was increased further from 6 g/kg (0.15 ml) to 8 g/kg (0.2 ml) and then to 12 g/kg (0.3 ml), there was a progressive decrease in the tumor growth delay observed. The dose of 4 g/kg was the optimal F44E level with single dose radiation therapy, giving a dose modifying factor of 2.4 +/- 0.2. This was true whether administered as a 48% (v/v) emulsion in 0.1 ml or as a 16% (v/v) emulsion in 0.3 ml. When the injection volume was varied from 0.1 ml to 0.4 ml at the 4 g/kg or 6 g/kg dose, thereby varying the emulsion concentration from 48% (v/v) to 12% (v/v) or 18% (v/v), the results tended to indicate that the volume of injection may be more important than the emulsion concentration, i.e., an injection volume of 0.2 ml produced the greatest tumor growth delay for both doses, and the emulsion concentration of 0.2 ml and 4 g/kg of F44E is 24% (v/v) whereas the emulsion concentration of 0.2 ml and 6 g/kg of F44E is 36% (v/v). Administering any dose of the emulsion with carbogen for 1 h prior to and during the radiation fraction on Day 1 only of a daily fractionated radiation protocol (3 Gy/fraction x 5 days) had very little effect on tumor growth delay compared to radiation and daily carbogen breathing. When F44E was administered on treatment Days 1, 3, and 5 with carbogen breathing, there was an increased effect on tumor growth delay which reached a maximum at 4 g/kg (0.1 ml) of 10.0 +/- 1.2 days compared with 6.7 +/- 1.0 days for radiation with daily carbogen breathing. However, when the F44E emulsion was administered every day with fractionated radiation and carbogen breathing, there was a marked enhancement in tumor growth delay observed across the entire dosage range, from 1.2 g/kg to 12 g/kg.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Influence of scheduling on two-drug combinations of alkylating agents in vivo.

The effects of schedule and sequence on the survival of EMT6 tumor cell and bone marrow (CFU-GM) obtained after treatment using combinations of cyclophosphamide (CTX) and thiotEPA or melphalan (L-PAM) were examined and analyzed by isobologram methodology. On a single-injection schedule, when CTX and thio-tEPA were given simultaneously or thiotEPA was given prior to CTX, the result was slightly greater than additive tumor-cell kill. However, when CTX preceded thiotEPA by 4 h, there was less than additive cell kill. When the interval between the administration of the two drugs was 8 h, both sequences of the drugs produced greater than additive tumor-cell kill. Simultaneous administration of CTX and thiotEPA on a multiple-injection schedule resulted in sub-additive tumor-cell kill. On the multiple-injection schedule, extending the interval between injections of CTX and thiotEPA to 4 and 8 h resulted in increasing tumor-cell kill. With the 4- and 8-h intervals, no significant sequence-dependent difference in tumor-cell kill was obtained. The results of CTX and L-PAM combinations paralleled those of CTX and thiotEPA. Bone marrow (CFU-GM) survival was used as a representative normal tissue with which to compare tumor-cell survival after each treatment to obtain a measure of therapeutic effect. The trends for the ratios of bone marrow: tumor cell survival were the same for the treatment sequences of CTX with thiotEPA or L-PAM; however, greater magnitudes of differential tumor-cell kill were obtained with CTX L-PAM combinations. Using this measure, the greatest therapeutic effectiveness was seen with single-dose L-PAM or thio-tEPA followed 4 h later by CTX and with CTX given as a single or as multiple doses followed 8 h later by L-PAM or thiotEPA. Such data from tumor-model systems may be useful in the development of more effective alkylating agent regimens for use in the clinic.

Alkylating Agents↗

PubMed1989

Radiation therapy of seminoma: 17-year experience at the Joint Center for Radiation Therapy.

One hundred and sixteen patients with stage I and II primary testicular seminoma were treated at the Joint Center for Radiation Therapy (JCRT) between 1968 and 1984. Complete follow-up is available for 114 patients (98%) with a median follow-up time of 6 years. Actuarial relapse-free survival (RFS) and survival for the entire group at 10 years were 94 and 86%, respectively, with 27 patients still at risk beyond 10 years. Actuarial RFS and survival at 10 years by stage were 97 and 92% for stage I, 93 and 81% for stage IIa, 100 and 100% for stage IIb, but only 75 and 51% for stage IIc. The difference in actuarial survival between stage IIc patients and stage I, IIa and IIb patients was significant (p less than 0.01). These results indicate that radiation therapy is excellent treatment for stage I and II seminomas as long as the largest mass of disease is not greater than 5 cm (stage IIc). Patients with stage IIc seminoma are now treated with cisplatin-containing combination chemotherapy followed by radiation therapy to areas of bulk disease. Although the majority of patients with stage II disease in this series received mediastinal irradiation, this is no longer recommended at the JCRT.

Actuarial Analysis↗

PubMed1989

Platinum complexes of triaminotriphenylmethanes: interaction with DNA and radiosensitization.

Complexes of the negatively charged tetrachloroplatinum (II) dianion and the positively charged triaminotriphenylmethane nuclear dyes, Basic Fuchsin and Methyl Green have been prepared. Elemental analysis indicated that the complexes associate as PtCl4(Basic Fuchsin)2 and PtCl4(Methyl Green) in neutral, tight ion pairs. Studies with pBR322 DNA indicated that Pt(Basic Fuchsin)2 and Basic Fuchsin produced no irreversible DNA changes, but that Pt(Methyl Green) readily and Methyl Green less efficiently produced single strand breaks in the DNA. Cytotoxicity studies in exponentially, growing asynchronous EMT6 cells in vitro showed that Pt(Basic Fuchsin)2 was more cytotoxic than Pt(Methyl Green) and that both complexes were more toxic to normally oxygenated than hypoxic cells and to cells at normal vs. acidotic pH (6.45). Radiation studies, also in EMT6 cells, demonstrated that Pt(Methyl Green) was an effective radiosensitizing drug in hypoxic cells (dose modifying factor [DMF] 1.9), but that neither the free dyes nor Pt(Basic Fuchsin)2 had significant radiosensitizing activity. In vivo studies in the FSallC fibrosarcoma confirmed the radiosensitizing properties of Pt(Methyl Green) (DMF 2.7), and indicated that Pt(Basic Fuchsin)2 also had some activity (DMF 1.4) which was equivalent to that of mizonidazole (DMF 1.4). These investigations suggest that these or similar platinum-dye complexes may have important antitumor applications in the human clinic.

Animals↗

PubMed1989

Effect of heat on the cytotoxicity and interaction with DNA of a series of platinum complexes.

The effect of elevated temperature on the cytotoxicity and interaction with DNA of a series of platinum(II) complexes was examined. CDDP showed greater enhancement in cell killing with heat than the other platinum(II) complexes. There were approximately 2 decades enhancement in cell killing by 10 microM CDDP at 42 degrees C compared to 37 degrees C. The other potential cross-linking agents also showed increasing cytotoxicity with increasing temperature. K2PtCl4 (500 microM) killed about 15 times more cells at 43 degrees C than at 37 degrees C and KPt(NH3)Cl3 (500 microM) killed about 18 times more cells at 43 degrees C than at 37 degrees C. The cytotoxicity of the triammine and tetraammine complexes was less influenced by temperature. There was no significant difference in the cytotoxicity of [Pt(NH3)3Cl]Cl at any of the temperatures examined. The cytotoxicity of [Pt(NH3)4]Cl2 (500 microM) was increased about 7-fold at 43 degrees C compared to 37 degrees C, but the total cell killing by this complex at 43 degrees C was less than 1 log. Carboplatin (250 microM) was about 5 times more toxic at 42 degrees C and killed about 2.5 decades more cells at 43 degrees C than at 37 degrees C. Although there was little enhancement in the cytotoxicity of trans-Pt(NH3)2Cl2 at 42 degrees C compared to 37 degrees C trans-Pt(NH3)2Cl2 (500 microM) was about 7 times more cytotoxic than at 37 degrees C. The interaction of the various drug/temperature treatments with supercoiled pBR322 plasmid DNA was examined to assess the effect of heat on the reaction of these agents with DNA. At 42 degrees C, CDDP was able to gradually alter the gel electrophoretic mobility of the plasmid DNA to near that of the linear form. This change also occurred at 37 degrees C but at a much slower rate. Carboplatin effected similar changes in the superhelical pBR322 DNA, and the effect of temperature appeared to increase the rate of the reaction. Trans-Pt(NH3)2Cl2 also interacted with the supercoiled DNA, but at a slower rate than CDDP even under hyperthermic conditions. These results indicate that neutral platinum complexes capable of cross-linking DNA interact positively with temperature elevation to increase cytotoxicity, and, that of the platinum complexes that meet these criteria, the effect of hyperthermia is greatest with CDDP.

Animals↗