Thermochemotherapy: synergism between hyperthermia (42-43 degrees) and adriamycin (of bleomycin) in mammalian cell inactivation

Trans-catheter hepatic arterial injection of lipiodol soluble anti-cancer agent SMANCS and ADR suspension in lipiodol combined with arterial embolization and local hyperthermia for treatment of hepatocellular carcinoma

The clinical effect and safety of Lp-TAE alone and combined with radiofrequency (RF) capacitive hyperthermia (HT) were evaluated in 20 patients with hepatocellular carcinoma (HCC) associated with cirrhosis of the liver. After the oily carcinostatic agents were administered by Lp-TAE, HT, at a temperature of greater than 42.5 degrees C, was induced for 40 min, twice a week by an RF of 8 MHz for a total of 10 to 38 times. The response rate was 40% in the 10 cases that were treated with Lp-TAE combined with HT and 20% in the 10 cases that were treated with Lp-TAE. The patients who were treated with Lp-TAE combined with HT had a tendency to have better survival rates than those of the Lp-TAE group (p less than 0.099). The main side-effects of Lp-TAE combined with HT were low-grade fever, localized pain, myelo-suppression and liver dysfunction, but these were transient and eventually disappeared.

Combination radiotherapy of urinary bladder carcinoma with chemohyperthermia

The combination therapy of urinary bladder cancer with radiation and hyperthermia with bleomycin was investigated. Immediately following daily external irradiation (40 Gy/4 weeks), patients were irrigated with a solution of warmed saline (intravesical temperature, 42-43 degrees C) containing 30 micrograms/ml bleomycin. Of a total of 56 patients, complete responses were observed in 25, and partial responses in 21. Among T2-T3 cases, an 84% response rate was noted in combination therapy, whereas a 56% response rate was observed after radiation alone (50-70 Gy). The side-effects of the combination therapy were limited to reversible bladder irritation, and bladder capacity could be maintained within normal limits. These results suggest that combination therapy represents an effective conservative therapy for the management of bladder cancer.

Effects of cis-diamminedichloroplatinum (CDDP) and cis-diammine (1,1-cyclobutanedicarboxylate) platinum (CBDCA) on thermotolerance development and thermosensitivity of the thermotolerant cells

The interactive effects of combined treatment with heat and CDDP (0.5 micrograms/ml) or CBDCA (10 micrograms/ml) were examined on the surviving fractions of V-79 cells. Both CDDP and CBDCA treatment induced a slight enhancement in thermosensitivity of thermotolerant cells. The development of thermotolerance during step-up heating was partially inhibited by simultaneous treatment with CDDP or CBDCA throughout the heating process. Simultaneous heat treatment at 42 degrees C with either drug showed marked interactive effect and inhibited the thermotolerance developed during 42 degrees C heating.

Treatment of experimental tumors with a combination of a pulsing magnetic field and an antitumor drug

We investigated the effects of a combination treatment involving a pulsing magnetic field (PMF) and an antitumor drug, mitomycin C (MMC), on two experimental tumors (fibrosarcoma KMT-17 and hepatocellular carcinoma KDH-8) in WKA rats, paying attention to possible potentiation of the therapeutic effect of the antitumor drug. PMF was obtained using a system generating a pulsed current in a solenoid coil. On day 7 after tumor implantation into the right thighs of rats, the region of the tumor was exposed to PMF (frequency 200 Hz, mean magnetic flux density 40 gauss) for 1 h immediately after iv injection of MMC at a dose of 1 mg/kg. Survival rates at day 90 of KMT-17 implanted rats were 0% (0/10) in the non-treated group, 34% (4/12) in the MMC-treated group, 47% (6/13) in the PMF-treated group and 77% (10/13) in the MMC/PMF combination group. The increase of life span (ILS) of KDH-8-implanted rats in the combination therapy group was significantly prolonged (%ILS 17.6%) compared with that in the MMC-treated (%ILS 3.4%) and PMF-treated (%ILS 7.6%) groups. By using cultured cells of the above two lines of tumor, the therapeutic effects of MMC and PMF were also determined from the cell colony-forming efficiency in soft agar. The colony-forming efficiencies of both cell lines were significantly suppressed in the combination therapy group compared with those in the other single therapy groups. The present results indicate that PMF exhibited a potentiation of the antitumor effect of mitomycin C.

Effects of hyperthermia on the membrane potential and Na+ transport of V79 fibroblasts

The effects of hyperthermia (41-43 degrees C) on the membrane potential (calculated from the transmembrane distribution of [3H]tetraphenylphosphonium) and Na+ transport of Chinese hamster V79 fibroblasts were studied. At 41 degrees C, hyperthermia induced a membrane hyperpolarization of log phase cells (5 to 26 mV) that was reversible upon returning to 37 degrees C. The hyperpolarization was inhibited 50% by 1 mM ouabain or 0.25 mM amiloride, an inhibitor of Na+:H+ exchange. Shifting temperature to 41 degrees C increased ouabain-sensitive Rb+ uptake indicating activation of the electrogenic Na+ pump. At 43 degrees C for 60 min, the membrane potential of log phase cells depolarized (20-35 mV). Parallel studies demonstrated enhanced Na+ uptake at 41 degrees C only in the presence of ouabain. At 43 degrees C, Na+ uptake was increased relative to controls with or without ouabain present. At both 41 and 43 degrees C, 0.25 mM amiloride inhibited heat-stimulated Na+ uptake. Na+ efflux was enhanced at 41 degrees C in a process inhibited by ouabain. Thus, one consequence of heat treatment at 41 degrees C is activation of Na+:H+ exchange with the resultant increase in cytosolic [Na+] activating the electrogenic Na+ pump. At temperatures greater than or equal to 43 degrees C, the Na+ pump is inhibited.

The effect of ultrasound on the cytotoxicity of adriamycin

The effect of continuous wave ultrasound exposures on the cytotoxicity of adriamycin has been studied. It has been found that 2.6 MHz, 2.3 Wcm-2 (spatial average) ultrasound can enhance the cell killing potential of adriamycin both in suspensions of single V79 chinese hamster fibroblast cells and in spheroids formed from these cells. The ratio of the slopes of the survival curves for single cell suspensions is 1.5. For spheroids, the growth delay is increased by 1.3 days by simultaneous ultrasound exposure. Flow cytometric studies of the intracellular concentration of adriamycin following ultrasound exposure reveals that this is increased when compared with that measured when the cells are only exposed to adriamycin. Evidence is presented to suggest that this is a non-thermal effect of ultrasound.

Hyperthermia catheter implantation and therapy in the brain. Technical note

For the treatment of malignant gliomas, a technique for implanting hyperthermia catheters was developed that utilized a stereotactic template and head-stabilization frame mounted on a computerized tomography (CT) scanner. Computerized tomography scans were used to measure tumor dimensions and to determine the number, implantation depths, and active heating lengths of the catheters, which were implanted through twist-drill holes while the patient was in the CT room. Heat was subsequently delivered via implanted catheters using a computer-controlled hyperthermia system, which partially compensates for heterogeneous and time-varying tumor blood flow.

Antiproliferative effect of hyperthermia and ACNU on cultured human malignant melanoma cells

Human malignant melanoma cultured cells were treated either with ACNU (1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chlorethyl)-3-nitro sourea hydrochloride), hyperthermia, or the combination of ACNU and hyperthermia. The combination treatment inhibited the cell growth to a slightly synergistic degree compared to the respective single treatments. The present in vitro experimental results support in part the finding of our previous report that the combination treatment with ACNU and hyperthermia have a significantly synergistic antitumor effect to human melanoma transplanted to nude mice. However, the synergistic effect was much less intense in the present in vitro experiment. The difference may have resulted from the environmental differences between in vitro and in vivo experimental systems.

Enhanced killing of human small cell lung cancer by hyperthermia and indium-111-bleomycin complex

Indium-111-bleomycin complex (111In-BLMC) is a radiopharmaceutical agent that produces tumor regression in mouse glioma in vivo and kills human small cell lung cancer (SCLC) cells in vitro. The interaction between hyperthermia and 111In-BLMC against human SCLC (N417) cells was studied for bleomycin (BLM) (15 micrograms/ml) or 111In-BLMC (40-50 microCi carried by 15 micrograms BLM/ml) for 5 min or 1.5, 2, or 4 hr at 37 degrees C or 43 degrees C exposures. Cell survival was determined by colony formation in soft agarose. There was a synergistic effect for 111In-BLMC and hyperthermia for cell killing. At 37 degrees C, the percent survival of N417 cells for BLM alone was 25.9%, and for 111In-BLMC it was 13.2%; at 43 degrees C, survival was 5.3% for BLM alone and 1.2% for 111In-BLMC by a 4 hr treatment. Effectiveness was greater when 111In-BLMC was combined with hyperthermia.

Sensitivity to thermochemotherapy of AKR lymphoma and B16 melanoma variants of malignancy

Drug resistance, which so often accompanies tumor progression, has been shown to be related to changes in membrane properties which may result in decreased drug accumulation in the tumor cell. A correlation between sensitivity to thermochemotherapy and degree of malignancy was found in the AKR lymphoma system. Hyperthermia increased adriamycin (ADR) uptake and concomitantly its cytotoxicity to AKR lymphoma cells. Moreover, these effects were more pronounced on a variant of high malignancy (HM) than on a low malignancy (LM) one. Fluorescent microscopy, as well as cytofluorometry, indicated that lymphoma cells treated by ADR at 43 degrees C were more permeable to the cytotoxic agent than those exposed to the chemotherapeutic substance at 37 degrees C. Cytofluorometry indicated the presence of a minor cell subpopulation with low ADR uptake in the HM variant, not found in the LM one. Fluorocytometry also showed that the temperature-dependent increased ADR uptake was more marked in the HM than in the LM variant, explaining the differential effect of thermochemotherapy on the two lymphoma variants. However, correlation between degree of malignancy and sensitivity to thermochemotherapy is not a general feature. In contrast to the results obtained in the AKR lymphoma system, in the B16 melanoma the low malignancy variant, F1, was more markedly affected by the combined treatment than the F10 variant. The increased cytotoxic effect of ADR by supranormal temperatures in the F1 variant was shown to be due to an augmented drug uptake. The results suggest that drug resistance in late stages of tumor progression can be overcome by an agent acting on the cell membrane. However, the data also indicate the necessity of assaying cancer treatment modalities, including those designed to circumvent drug resistance, on various tumor system models.

Thermochemotherapy for B16 melanoma: combination therapy of hyperthermia, melphalan, and CCNU in mice

We studied, by means of quantitative histopathological methods, the changes that took place in B16 melanoma implanted into C57BL/6J mice after combination treatment of hyperthermia, melphalan, and 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU). The studies were made on animals sacrificed on days 11, 18, and 25 after implantation. Tumors in treated animals showed a progressive delay in growth, a noticeably reduced number of metastases, and diminution of proliferative capacity. However, this treatment did not affect necrosis, stroma, capsule, or cell infiltration. Ultrastructurally, signs of cell damage were constantly present.

Hyperthermic effects on cell killing in Dictyostelium discoideum amoebae treated with DNA-damaging agents

Hyperthermic effects on cell killing of amoeboid cells treated with DNA-damaging agents of Dictyostelium (D). discoideum were studied. Though the amoeboid cells are usually cultured at 23 degrees C, heat treatment at 30 degrees C for 15 min immediately after UV irradiation markedly enhanced cell killing, while not observed in the case of heat treatment immediately before UV irradiation. Similar effects were observed in the case of heat treatment after treatment with 4-nitroquinoline 1-oxide, cis-platinum(II) diamminedichloride or 8-methoxypsoralen photoaddition, while not observed when heat was applied before these treatments. On the contrary, little enhancement by heat treatment was observed even after treatment with N-methyl-N'-nitro-N-nitrosoguanidine or methylmethanesulphonate. The hyperthermic mechanisms in D. discoideum are discussed, based on a diverse set of DNA lesions caused by chemicals and DNA repair mechanisms for them.

Effects of adriamycin and hyperthermia on cellular uptake of [3H]thymidine and its significance for the incorporation into DNA

Inhibition of the salvage DNA synthesis was studied in ascites tumour cells up to 240 min at moderately increased temperatures of 39 degrees C, 40.5 degrees C and 43 degrees C alone or in combination with adriamycin (ADR). Hyperthermia and ADR acted additively on salvage DNA synthesis. The [3H]thymidine (TdR) incorporation was strongly related to the cellular uptake of [3H]TdR. In order to evaluate the significance of the decrease in [3H]TdR uptake for the incorporation into DNA, the thymidine kinase (TK) has also been studied. TK activity started to decrease at a temperature of 39 degrees C, probably due to inhibition of translation and/or transcription of the enzyme, and was almost completely inhibited at 43 degrees C. ADR did not affect TK activity. Inhibition of DNA synthesis by aphidicolin neither decreased the ability of the cell to take up [3H]TdR nor the ability to affect TK activity. We concluded that moderate increases in temperature alone, or in combination with ADR, inhibit salvage DNA synthesis by inhibition of TdR uptake, possibly due to inhibition of phosphorylation; ADR, on the contrary, inhibits TdR uptake by other mechanisms such as changes in membrane function.

Effect of hyperthermia on intracellular drug accumulation and chemosensitivity in drug-sensitive and drug-resistant P388 leukaemia cell lines

Enhancements of the drug-induced cytotoxicity and modifications of drug transmembrane equilibria caused by hyperthermic treatment were analysed on P388/S and P388/R murine leukaemia cell lines. The P388/R cell line was derived from the P388/S cell line by drug selection of mutant, drug-resistant clones; it expresses a pleiotropic drug resistance towards some chemotherapeutic drugs such as doxorubicin, daunorubicin and etoposide, but is only weakly resistant towards other drugs as cis-diammine-dichloroplatinum. Hyperthermic treatment enhanced the drug cytotoxic effects much more on the P388/R cell line than on the P388/S line, but the cytotoxic enhancements were consistent only for the drug towards which the P388/R cell line expresses pleiotropic resistance. Intracellular drug accumulation analysis and drug transmembrane equilibria determinations indicated that the resistance of both cell lines to the intracellular drug was not affected by hyperthermic treatment, whereas variations in drug influx, but not in drug extrusion, were induced by heat treatment. The study suggested, therefore, that hyperthermia does not modify intracellular chemosensitivity of either cell line, but acts on membrane permeability by facilitating attainment of the intracellular drug concentrations needed to cause the cytotoxic effect.

A new method of investigating the efficacy of regional thermotherapy in subcutaneous xenografts of nude mice

A new method of investigating the efficacy of regional thermotherapy in subcutaneous xenografts of nude mice is reported. The use of high frequency hyperthermia was well tolerated by the sensitive animals and allowed an exact continuous temperature measurement in different tumor regions. The interstitial procedure in this model could be the best approach for later clinical use in urology, e.g. for prostate treatment and is an alternative to the transrectal hyperthermia application.

Sensitivities of bleomycin-resistant variant cells enhanced by 40 degrees C hyperthermia in vitro

Cultured mammalian cells of higher (mouse L) and lower (Chinese hamster V-79) sensitivities to bleomycin (BLM) were repeatedly treated with BLM (0.1 mg/ml), through which BLM-resistant variant strains were induced. Sensitivities of these variant strains to BLM were enhanced by simultaneous treatment with 40 degrees C hyperthermia.

Predicting the sensitivity of human cancers to combined chemotherapy and hyperthermia

In order to estimate its ability to predict the thermochemosensitivity of human cancers, a rapid in vitro assay based on morphological changes in the nucleus was performed on eight different human tumors (four malignant melanomas, two lung tumors, one renal carcinoma, and leukemia K-562). Nude mice, implanted with tumors, supplied the tumor material, with the exception of leukemia. Nimustine, melphalan, mitomycin C, vincristine and vinblastine were tested. Tumor cells developed karyorrhectic changes after incubation for 4 h with each of the aforementioned five drugs. An increase in the karyorrhectic changes was observed with hyperthermia at 43 degrees C. The individual tumors showed different sensitivities to 43 degrees C. Five of the eight tumors were significantly sensitive to 43 degrees C. However, in two thermosensitive tumors no drug enhancement was recognized at 43 degrees C. In four tumors several drugs were synergistically enhanced by hyperthermia at 43 degrees C. This study suggests that this simple method may be of clinical use in predicting response to thermochemotherapy.

Heat shock phenomena in Aspergillus nidulans. II. Combined effect of heat and bleomycin to heat shock protein synthesis, survival rate and induction of mutations

The combined action of hyperthermia and Bleomycin on Aspergillus nidulans was studied at three different levels: mycelial protein synthesis, spore viability and induction of mutations. It was found that Bleomycin treatment of preincubated mycelia during the heat shock enhances the incorporation of 35S-methionine into heat shock bands. Furthermore, simultaneous treatment with hyperthermia (43 degrees C) and Bleomycin results in greater cytotoxic activity in spores and in a higher induction rate of point mutations.

Whole body hyperthermia and heat-sensitizing drugs: a pilot study in canine lymphoproliferative disease

Thirteen dogs were entered into a pilot study to assess the toxicities associated with polyamine biosynthetic enzyme inhibitors as heat sensitizing drugs and whole body hyperthermia either alone or in combination. Disease-free and tumour-bearing animals were entered in an effort to assess the response of canine lymphoproliferative disorders as well. Conclusions reached were as follows. (1) A large tumour burden precludes treatment. (2) Liver involvement and decreased platelet numbers would appear to offer a grave prognosis for survival and should be assessed closely in determining eligibility. (3) Polyamine biosynthetic enzyme inhibitors and whole body hyperthermia appear to be tumoricidal alone or in combination, although less effective and with greater toxicities than accepted chemotherapeutic regimens. (4) Heat sensitization in vivo has not yet been demonstrated.

Enhancement of the in vitro cytotoxicity of bouvardin by verapamil alone and combined with hyperthermia in Sarcoma 180 and Ehrlich ascites carcinoma cells

The cytotoxic effect of bouvardin (BVD) a protein synthesis inhibitor was studied separately and in combination with verapamil (VRP), a vasodilator and hyperthermia (43 degrees C) against Sarcoma 180 (S 180) and Ehrlich ascites carcinoma (EAC) tumour cells in vitro. S 180 cells exhibited natural resistance to hyperthermia and BVD, whereas EAC tumour cells were found to be sensitive. VRP alone did not show cytotoxicity to either tumour cells. A combination of BVD and VRP at an elevated temperature resulted in a greater cell kill in the EAC tumour cell line whereas the natural resistance of S 180 tumour cells to the drug BVD and hyperthermia was circumvented by combination with VRP. Combination of BVD, hyperthermia and VRP resulted in greater cell kill, compared to separate treatment with the single agents. The cytotoxicity was evaluated by comparing the inhibition of incorporation of 3H-thymidine in treated cells to that in untreated cells.

Enhanced chemosensitivity of cells from malignant effusions under condition of exposure to high temperature

Utilizing a clonogenic assay, the effects of hyperthermia and selected chemotherapeutic drugs on growth of cells from malignant effusions were studied. Fourteen of 25 samples obtained from 25 patients with various carcinomas formed at least 30 colonies per plate. Exposure of the cells to heat at 42 degrees C for 1 hr before the plating slightly inhibited the colony growth. The drugs, adriamycin (AM) and mitomycin C (MMC), were tested at 3 different concentrations. When the cells were treated with these two drugs for 1 hr at 42 degrees C, the percent of surviving colonies was significantly decreased, as compared to findings at 37 degrees C, in both groups, at 3 different concentrations. The combination of drugs and hyperthermia appeared to function synergistically in one-third of such cases. These results suggest that cells from malignant effusions in patients with various carcinomas were more sensitive to AM or MMC, under condition of a higher temperature (42 degrees C).

Enhancement of adriamycin-induced killing after delayed plating of plateau-phase V79-cells

Unfed plateau-phase cultures of Chinese hamster V79-cells were treated for 1 h with various amounts of adriamycin in the range between 0 and 10 micrograms ml-1 and subsequently either immediately trypsinized and plated to assay for survival, or reincubated in medium collected from replicate plateau-phase cultures and returned to the incubator for various periods of time before plating. Significantly less killing was observed, for the same adriamycin dose, in cells treated in the plateau-phase and plated immediately thereafter as compared to cells treated while actively growing. When cell trypsinization and plating was delayed for up to 22 h, a significant increase in killing was observed, and the survival curve obtained approached that observed after treatment with adriamycin of growing cells. Initially almost exponential kinetics were observed for this potentiation of adriamycin-induced cell killing with a t37 of approximately 2 h. Cell survival was still decreasing after 22 h of post-treatment incubation in the plateau phase, with no clear indication for approaching a plateau. However, longer incubations, to establish a plateau, were not possible due to degeneration of the cultures. Flow cytometry measurements of the intracellular adriamycin content showed only a small difference between exponentially growing and plateau-phase cells despite the significant differences in the number of cells per culture at the time of treatment. The rate at which adriamycin-related fluorescence decayed after adriamycin treatment was slightly higher for cells trypsinized and exposed to fresh medium than for cells kept in the plateau-phase. The results indicate the importance of the physiological state and the post-treatment incubation conditions of cells for the final effect of adriamycin on survival.

Hyperthermia, chemotherapeutic agents and oncogenic transformation

The modulating effects of hyperthermia on cytotoxity and oncogenicity of several chemotherapeutic agents were investigated using the C3H 10T1/2 cell system. Logarithmic phase cultures of 10T1/2 cells were treated with various doses of cis-platinum or bleomycin sulphate for 2 h, either alone or with simultaneous hyperthermia (42 degrees C for 2 h). In a second set of experiments, cells were treated for 24 h with either melphalan or cis-platinum followed by a 2 h heat treatment. While hyperthermia alone was found to be ineffective in inducing oncogenic transformation and was only moderately cytotoxic, concurrent hyperthermia with drug treatment enhanced both the toxicity and oncogenic transforming potential of drugs 3-4-fold in C3H 10T1/2 cells. Sequential heat after drug treatment, however, was found to increase toxicity slightly but had no effect on the oncogenicity of the drugs.

Stability of solutions of antineoplastic agents during preparation and storage for in vitro assays. II. Assay methods, adriamycin and the other antitumour antibiotics

The methods used to test drug stability are discussed in the light of two recent publications using biological assays. It is concluded that, as far as possible, stability-indicating assays should be used so that possible false results do not lead to erroneous conclusions. Many of the results of the stability studies with adriamycin were found to be at variance with each other, with a 20-fold difference in stability being reported in one case by different groups from virtually identical experiments. Definitive statements about adriamycin stability are therefore impossible, but it is clear that it is sensitive to light, adsorbs to membrane filters and containers (except polypropylene and siliconised glass), chelates metal ions and probably degrades rapidly in medium. Adriamycin's analogues may well have the same spectrum of sensitivity. Bleomycin, actinomycin D and neocarzinostatin were found to be stable for greater than or equal to 2 weeks at room temperature. All the other antitumour antibiotics investigated (except rubidazone) are stable for greater than or equal to 24 h at room temperature and longer at 5 degrees C. Almost all of them are sensitive to light and are most stable in neutral or slightly acid media, and many of them adsorb to membrane filters. They can probably all be stored frozen in solution.

Interstitial hyperthermia and iridium brachytherapy in treatment of malignant glioma. A phase I clinical trial

An oncolytic effect of hyperthermia in the 42 degrees to 43 degrees C range has been previously demonstrated in cell culture and animal models. To apply this modality clinically, an interstitial microwave antenna array system has been developed for the delivery of controlled hyperthermia to an intracranial tumor volume, and a Phase I clinical trial involving six patients with malignant gliomas was undertaken. The protocol to study technical feasibility and patient tolerance combined interstitial iridium-192 irradiation and interstitial hyperthermia with 60-minute hyperthermia sessions immediately before and after brachytherapy. After-loading catheters suitable for both treatment modalities were implanted using a computerized tomography-assisted technique. Thermometry data confirmed the ability of a microwave antenna system to achieve reliable temperature distributions, and reasonable patient tolerance was documented.

Interaction of bleomycin, hyperthermia and a calmodulin inhibitor (trifluoperazine) in mouse tumour cells: I. In vitro cytotoxicity

Evidence in the literature suggests that hyperthermia (HT) or inhibitors of calmodulin can increase the sensitivity of rodent cells to bleomycin (BLM) by interfering with DNA repair functions. In an attempt to explore methods of improving the efficacy of thermochemotherapy we have investigated the individual and combined effects of HT (44 degrees C) and the calmodulin inhibitor trifluoperazine (TFP, 30 micrograms ml-1) on early plateau phase monolayer cultures of mouse EMT6 tumour cells for simultaneous exposures to BLM. Early plateau phase cultures are relatively resistant both to HT and to BLM. The selected HT and TFP regimens (either alone or in combination) were non-toxic. Comparing the sensitizing effect (given by the ratio: Do BLM/Do BLM + modifier) of the various regimens on BLM-treated cells, we found that: TFP alone had a marginal effect (ratio 1.3), HT alone showed significant potentiation (ratio 19) and the combination of HT and TFP strongly sensitized (ratio greater than 110) cells to BLM cytotoxicity. We propose that the use of calmodulin inhibitors in thermochemotherapy is worthy of further evaluation.

Thermochemotherapy for malignant melanoma: overcoming heterogeneity in drug sensitivity

Endo B (melanotic) and W (amelanotic) human malignant melanomas originated from the same tumor, both known to be heterogeneous in drug sensitivity to ACNU [( 1-(4-amino-2-methyl-5-pyrimidinyl)-methyl-3-(2-chloroethyl)-3-nitroso- urea hydrochloride]), were treated experimentally with a combination therapy of ACNU and hyperthermia in mice. Whereas Endo W melanoma has no sensitivity, Endo B melanoma is sensitive to ACNU alone. However, in both types of melanomas, a marked synergistic effect of the combination therapy was noted. Histologically, marked degeneration of both tumor cells was detected. These results strongly suggest that thermochemotherapy may overcome the tumor heterogeneity in drug sensitivity.

Phase I trial of thermochemotherapy for brain malignancy

High-grade primary and refractory brain tumors and metastases to the brain from other primary sites are associated with a grave prognosis. Treatment, usually palliative, consists of some combination of surgery, radiation, and chemotherapy. Recently, noninvasive hyperthermia by magnetic-loop induction has been safely used to treat patients with advanced cancer in extracranial sites. Both disease regression and disease stabilization have been observed. This technique was recently applied to brain tumors in an animal model, and its safety was again demonstrated. As a result, a Phase I trial of noninvasive localized hyperthermia in combination with intravenous chemotherapy has been carried out in ten patients whose primary or metastatic brain tumors failed to respond to standard therapy. Ten patients underwent 23 thermochemotherapy sessions using the magnetic-loop induction device. The median, maximum temperature of normal brain after 1 hour of hyperthermia was 41.1 degrees C (range, 38.6 degrees C-43.4 degrees C); the median, maximum temperature of brain tumor was 42.5 degrees C (range, 38.8 degrees C-46.3 degrees C) (P less than 0.01). The temperatures of both the normal brain and brain tumor were obtained during 18 treatments. The tumor temperature was greater than the normal brain temperature in 15 of 18 treatments. In 78% of the treatments, the measured tumor temperature reached at least 42 degrees C, whereas the normal brain reached 42 degrees C in only 13% of the treatments. These data demonstrate the "selective inability" of brain tumor tissue to dissipate heat. Vital signs, intracranial pressure, and neurologic status were monitored throughout the hyperthermia treatments. No mortality or increase in chemotherapeutic toxicity could be attributed to the thermochemotherapy. In addition, there were no local complications or permanent neurologic complications. Two patients with elevated intracranial pressure before therapy had transient neurologic deficits that may have been exacerbated by the hyperthermia. It is concluded that this new, noninvasive modality not only produced effective intracranial tumor heating, but could be performed safely with the proper precautions. Phase II trials are warranted.

Degradation mediated OH radical generation from synthetic cyclic peroxides: ESR studies

Hydroxy radical generation on thermal decomposition of synthetic cyclic peroxides was determined by ESR using DMPO as a spin-trapping reagent. Both the 6- and 7-membered cyclic peroxides, 4-alkoxy-2,3-benzo-dioxan-1-ols and 4-alkoxy-2,3-benzodioxepin-1-ols, respectively, which were synthesized according to our idea of a radical-releasing drug, gave rise to DMPO-OH signals on heat treatment, i.e. under their degradation conditions. The signals were completely abolished with higher concentrations of OH scavenger.

Hyperthermia for cancer: a practical perspective

A causal relationship between hyperpyrexia and tumor regression was first suggested in 1866, when Busch reported the cure of a histologically diagnosed sarcoma in a middle-aged woman, following a bout of erysipelas. Over the years, interest in the effect of heat on cancer has remained alive, but this interest has increased dramatically in recent years. The literature on this subject is broadly reviewed and the clinical results discussed. It is apparent from clinical studies thus far that it is a relatively simple undertaking to treat superficial neoplasms with hyperthermia. However, the major challenges in clinical thermotherapy pertain to patients with deeply situated tumors. The lack of safe and reliable methods of monitoring temperature in deep tissues is a major impediment to a thorough understanding of thermal dosimetry in clinical hyperthermia, and routine thermal dosimetry in clinical hyperthermia will have to await the development of reliable noninvasive thermometry. As responses have been reported with modest levels of hyperthermia, the need for thermometry is somewhat lessened, given that invasive monitoring is imperfect and somewhat risky when used in deeply seated tumours. The eventual place of thermotherapy in the treatment of malignant tumours in man is as yet unclear and must be rigourously and thoroughly assessed in well-designed, prospective, randomized patient trials.

The Synergistic Effect of Hyperthermia and Chemotherapy on Murine Transitional Cell Carcinoma

The in vivo effect of hyperthermia and chemotherapy was studied in a murine transitional cell carcinoma model. Localized hyperthermia (43.5C) of 60 and 90 minutes duration was combined with systemic doxorubicin hydrochloride, cis-platinum, cyclophosphamide or mitomycin to treat tumors implanted into the hind legs of C3H mice. The data were compared to the results obtained from the application of hyperthermia or chemotherapy alone as well as to the natural growth rate of untreated tumors. Untreated tumors grew with an exponential rate and had a doubling time of 4 +/- 1.5 days. Animals bearing such tumors survived for 25 +/- 7 days. When treated with hyperthermia alone, there was no significant reduction in the growth rate and no improvement was noted in the survival time. Treatment with doxorubicin hydrochloride, cyclophosphamide or mitomycin administered alone was likewise not effective. Cis-platinum alone was able to induce a minimal decrease in the growth rate. When the administration of chemotherapy was accompanied by hyperthermia, significant synergistic effect was noted for doxorubicin hydrochloride, cis-platinum and cyclophosphamide (p less than .01); only the mitomycin and hyperthermia combination failed to improve survival and decrease the growth rate. The duration of the hyperthermia exposure influenced the degree of tumor response. Hyperthermia of 90 minutes duration resulted in consistently greater decrease in tumor growth rate with doxorubicin hydrochloride, cis-platinum or cyclophosphamide than 60 minutes of hyperthermia combined with the same agents. These results indicate that local hyperthermia combined with doxorubicin hydrochloride, cis-platinum or cyclophosphamide can induce tumor regression, increase tumor doubling time and improve the survival of the tumor-bearing animal. Only the hyperthermia-mitomycin combination did not result in significant improvement from the baseline values. Thus, hyperthermia combined with selected chemotherapeutic agents can have an adjuvant effect in the treatment of established, implanted mouse bladder tumors.

Attachment of fibroblasts following hyperthermia and ultrasound

The rate of cell attachment to the culture substratum is reduced in mouse L cells by hyperthermia at 44 degrees C. The time for 50 per cent attachment of the cells increases rapidly with increasing time of heating immediately before assay. The rate of attachment after 44 degrees C does not show a linear correlation with clonogenic survival, ruling out the use of attachment as a rapid assay of clonogenic survival. The attachment process is less sensitive to heat in cells made thermally tolerant by a prior heat treatment. In contrast, ultrasound irradiation at 37 degrees C and below the cavitational threshold (1.5 MHz, 2.2 W/cm2, 15 min) did not alter the rate of attachment, but at 44 degrees C, ultrasound decreased both clonogenic survival and the rate of attachment to a much greater extent than 44 degrees C alone. As the temperature increase caused by the ultrasound was less than 0.5 degrees C, the data provide evidence of a non-thermal component of ultrasound damage.

Effects of methylglyoxal bis(guanylhydrazone) on tumour and skin responses to hyperthermia in mice

Effects of methylglyoxal bis(guanylhydrazone) (MGBG) on tumour and skin responses to hyperthermia (42 degrees C) were examined in C3H mice. MGBG (50 mg/kg) was administered intraperitoneally to mice 4 hours before hyperthermic treatment. The tumour (FM3A) growth time was elongated by an amount dependent on the exposure time of treatment at 42 degrees C (60, 90 and 120 min). Pre-treatment of mice with MGBG (50 mg/kg, i.p.) apparently further lengthened the tumour growth time after treatment at 42 degrees C. No significant damage of foot skin was caused by 42 degrees C hyperthermia. Pre-treatment with MGBG did not make the foot skin susceptible to the heating. From these findings, it can be considered that MGBG or related less-toxic compounds may have a clinical advantage for the mild (42 degrees C) hyperthermic treatment in cancer therapy.

Doxorubicin, cyclophosphamide, and whole body hyperthermia for treatment of advanced soft tissue sarcoma

Eleven patients with advanced soft tissue sarcoma were treated with whole body hyperthermia (41.8 degrees C-43.0 degrees C) for 2 hours, doxorubicin (45 mg/m2) at the beginning of peak temperature and cyclophosphamide (1000 mg/m2) 6 hours after doxorubicin. Warming was accomplished with a nylon and vinyl mesh water perfused suit and heating blankets under barbiturate anesthesia. Thirty-five thermochemotherapy treatments were administered after an initial baseline euthermic course. There were two complete and two partial responses including three of three liposarcomas and one of two leiomyosarcomas, and there were two disease stabilizations . Morbidity included anasarca, nausea and vomiting, diarrhea, myalgias, mild surface burns, perioral herpes simplex, reversible neuropathy, hypotension, and cardiac arrythmias . Hyperglycemia and hypophosphatemia were found during heating, and normalized at 24 hours. Liver enzyme elevations occurred 24 hours after heating and normalized within 1 week. A uniform platelet decrease (mean, 107,000/microliter) was found at 24 hours. Thermochemotherapy was found to be a feasible approach for selected patients with advanced soft tissue sarcoma for the subset of liposarcomas and leiomyosarcomas.

Clinical thermochemotherapy. A controlled trial in advanced cancer patients

In vitro and in vivo animal studies and some clinical trials have shown apparent benefit from thermochemotherapy; however, this treatment modality has not been adequately tested in humans. This investigation evaluated response to and toxicity of secondary thermochemotherapy, using each patient as his own control. Patients with advanced cancer who had documented disease progression while receiving chemotherapy alone were subsequently treated with the same drug, by the same dose and route, combined with localized hyperthermia. Thirty-four patients whose diseases included metastatic colon carcinoma, melanoma, sarcoma and hepatoma in viscera (29) or surface tissues (5) were treated with combination thermochemotherapy for 1 hour daily for 5 days/month. Effective heating from 41 to 45 degrees C minimum tumor temperature was possible in 17/19 (89%) tumors in which temperatures could be measured safely. The authors observed 5 (15%) tumor regressions for 1 to 5 months (median, 2 months), and 19 (56%) tumor stabilizations (growth arrest of previously progressive disease) for 1 to 9 months (median, 4 months). Subjective improvement in activity and/or pain control occurred in 6 (18%) patients and 20 (59%) had no progression of symptoms during treatment. Moreover, there was no detectable morbidity from localized hyperthermia, and no evidence of increased chemotherapy toxicity. While the mechanism(s) of response is poorly understood, the documented disease regressions and stabilizations of previously progressive disease in 24 (71%) patients during secondary combination thermochemotherapy indicates that the addition of hyperthermia may have useful anticancer activity. Expanded trials are warranted.

Thermochemotherapy for malignant melanoma: combination therapy of ACNU and hyperthermia in mice

B16 melanoma (mouse melanoma) and C24 melanoma (human malignant melanoma) transplanted in mice were treated by a combined therapy of ACNU [1-(4-amino-2-methyl - 5 - pyrimidinyl) - methyl - 3 - (2 - chlorethyl) - 3 - nitrosourea hydrochloride] (10 mg/kg) and hyperthermia (43 degrees C, 30 min). In both types of melanoma, a marked synergistic effect of the combined therapy was noted. Particularly in C24 melanoma a reduction in the size of tumor was observed. Histopathologic findings revealed a strong degeneration such as destruction of the tumor structure and vacuolization of nuclei.