Enhanced tumor control following sequential treatments of photodynamic therapy (PDT) and localized microwave hyperthermia in vivo

Photodynamic therapy (PDT), or photoradiation therapy (PRT), utilizing hematoporphyrin derivative (HPD) as photosensitizer and an argon-dye laser system as the light source, was used alone and in combination with localized microwave hyperthermia (2450 MHz) to treat axillary tumors of the SMT-F mammary carcinoma in mice. Thirty-minute heat treatments were applied either immediately before or immediately after a standard PDT treatment of 630 nm light at 75 mW/cm2 for 30 min (135 J/cm2) given 24 hr post-7.5 mg/kg HPD, intraperitoneally (i.p.). Tumor control as judged by lack of tumor regrowth 35 days or longer after the combined treatments was compared to that following each treatment when given alone. Little or no enhancement of tumor control was seen when sublethal temperatures of 37.5, 38.5, and 39.5 degrees C were applied for 30 min immediately following the PDT treatment. However, increasing levels of enhancement were seen when heat treatments of 40.5 and 41.5 degrees C or 44.5 degrees C, given for 30 min, were applied immediately before or after the photodynamic treatment.     

Potentiation of photodynamic therapy by heat: Effect of sequence and time interval between treatments in vivo

Photodynamic therapy (PDT) utilizing hematoporphyrin derivative (Hpd) as photosensitizer and an argon-dye laser as the light source was used alone and in combination with a localized microwave hyperthermia treatment to treat the SMTF mammary carcinoma in mice. A 30-min heat treatment at 44.5°C was applied 0–8 hr before or after a standard photodynamic treatment (67.5 or 135 J/cm², given 24 hr post-7.5 mg/kg Hpd). Potentiation of PDT by heat was found to be related to the sequence of the treatments and the time interval between them. When 44.5°C for 30 min was applied immediately after a 15-min PDT treatment, significant potentiation was seen (58% long-term tumor control vs 3 and 10%, respectively, for PDT and heat alone). This potentiation decreased with increasing time between PDT and heat, with tumor control values decreasing to 36, 20, and 14%, when 2, 4, and 8 hr, respectively, were allowed between treatments. Only additive effects of the independent therapies were found when this heat treatment was applied 0–8 hr before PDT. In other experiments, mice were treated with single or fractionated 30-min PDT treatments (two 15-min treatments separated by 0-,-2-, 4-, or 8-hr intervals). Decreases in tumor control were seen with increasing time interval; only minor differences in tumor control were seen when 4–8 hr was allowed between treatments compared to a single 15-min treatment.     

Photodynamic activity of lutetium-texaphyrin in a mouse tumor system.

BACKGROUND AND OBJECTIVE: New photosensitizers proposed for photodynamic therapy (PDT) treatment of tumors need to be evaluated in animal models to determine the parameters needed for treatment. They also need to be compared with existing photosensitizers for efficacy. We examined the PDT response to lutetium-texaphyrin (PCI-0123) in a mouse mammary adenocarcinoma model and compared it with the PDT response seen when using Photofrin. STUDY DESIGN/MATERIALS AND METHODS: DBA/2 mice with SMT-F tumors were used to explore PCI-0123 toxicity, laser light dose, and drug dose effects on PDT response and to determine the most effective time for light application. The PDT response of PCI-0123-treated tumors was compared with that of Photofrin-treated tumors. RESULTS: Treatment of tumors with 150 J/cm2 of 740 nm laser light 5-6 hr after PCI-0123 administration (40 mg/kg) resulted in a 100% response rate and a 55% cure rate. Tumors treated with 150 J/cm2 of 630 nm laser light 24 hr after Photofrin administration (10 mg/kg) resulted in a 67% response rate and a 16% cure rate. CONCLUSION: PCI-0123 was found to be a more effective photosensitizer than Photofrin.     

Photodynamic therapy using pheophorbide a and Nd:YAG laser.

The authors describe a new photodynamic therapy (PDT) method for malignant brain tumors. Pheophorbide a (Ph-a), the photosensitizer, has low toxicity, causes no skin sensitization and is activated with an acoustic Q switched neodymium yttrium-argon-garnet (Nd:YAG) laser which achieves deep tissue penetration. The Ph-a distribution in Fisher 344 (F344) rats bearing rat T9 glioma at 24 hours after intravenous injection was very low in the normal brain tissue, but significantly higher in the T9 glioma giving a tumor to normal brain tissue concentration ratio of 7.5:1. The in vitro survival rate of T9 glioma cells pretreated with Ph-a was 68.8 +/- 5.4% after laser irradiation for 20 minutes, significantly lower than in the control groups. This indicates that Ph-a was activated with the acoustic Q switched Nd:YAG laser causing the photodynamic effect. The survival rate after Ph-a pretreatment and laser irradiation in a waterbath at 44.0 degrees C was further reduced to 15.8 +/- 3.3%. In vivo PDT studies using T9 glioma cells inoculated into the dorsal region of F344 rats showed tumor eradication in four of six rats. The combination of PDT and laser hyperthermia produced tumor eradication in all six rats. The combination of PDT and hyperthermia is a promising method for tumor treatment.     

Experimental studies on combined chemotherapy with hyperthermia and ethanol for advanced esophageal cancer. II. Effects of combined treatments on tumor growth in tumor-bearing mice

The combined effects of local hyperthermia, bleomycin and ethanol were investigated using Lewis lung carcinoma (3LL) in female C57BL/6 mice and FM3A tumors in female C3H/He mice. The combined treatments were performed on days 4 and 7 or on days 4, 7 and 10 after tumor implantation. Hyperthermia at 43 degrees C for 60 min or 15 mg/kg of bleomycin resulted in mild reductions of tumor growth, respectively, whereas hyperthermia at 41 degrees C for 60 min alone did not show antitumor effects. Synergistic effects were observed with 43 degrees C hyperthermia and bleomycin. Furthermore the effects were enhanced by the combined use of ethanol (10% ethanol, 0.05 ml, i.t.). The antitumor effects of combined treatments of 41 degrees C hyperthermia and bleomycin were not so remarkable as those of 43 degrees C hyperthermia and bleomycin. In the combination of 41 degrees C hyperthermia, bleomycin and ethanol, marked increase of antitumor effects was observed particularly in 3LL tumor. A possible application of these findings to clinical therapy for advanced esophageal cancer was discussed.     

Intraoperative phototherapy (PDT) and surgical resection in a mouse neuroblastoma model

This study evaluates the effect of intraoperative photodynamic therapy (PDT) using the multiline argon laser (488-514 nm) or the argon-dye laser (630 nm) combined with surgical resection compared with surgical resection alone in reducing the incidence of C1300 neuroblastoma recurrence in mice. In the control groups, surgical resection alone resulted in 86% +/- 12% tumor recurrence. Surgical resection and intraoperative lasing without photosensitizer resulted in 75% +/- 27% tumor recurrence with the argon-dye laser and 55% +/- 18% recurrence with the multiline argon laser. In the treatment groups, surgical resection and intraoperative PDT at 630 nm resulted in 56% +/- 19% tumor recurrence whereas surgical resection and intraoperative PDT at 488-514 nm resulted in 21% +/- 7% tumor recurrence. The cause for the decrease in local recurrence in the control group using the multiline argon laser is unknown, but could it be due in part to hyperthermic effects. Intraoperative PDT was an effective adjunct to surgical resection in preventing local recurrence in this tumor model.     

Hyperthermic potentiation of photodynamic therapy employing Photofrin I and II: comparison of results using three animal tumor models

Hyperthermia induced by a microwave source (2,450 MHz) was used alone and in combination with photodynamic therapy (PDT) to treat the SMT-F, EMT-6, and RIF animal tumors in vivo. PDT was administered using either Photofrin I or II as the photosensitizer and an argon-pumped tunable dye laser (630 nm) as the light source. Greater than additive increases in long-term tumor control were achieved when hyperthermia was given immediately post-PDT in the SMT-F and RIF tumor systems. Only additive (or independent) increases in tumor control were achieved when hyperthermia was given immediately before PDT in all these tumor systems and when heat was applied post-PDT using the EMT-6 tumor. In a series of experiments using the SMT-F tumor, it was observed that decreases in PDT drug or light doses could be offset (in terms of tumor control) by the addition of a subsequent heat treatment. This result, along with others presented, indicates the clinical potential of PDT and hyperthermia as adjuvant cancer modalities.     

Microprocessor-controlled Nd:YAG laser for hyperthermia induction in the RIF-1 tumor.

Near-infrared radiation from a Nd:YAG laser at 1,064 nm was used interstitially or superficially to induce hyperthermia in RIF-1 tumors in C3H male mice. A single 600-microns quartz fiber with a 0.5-cm cylindrical diffusor or a weakly diverging microlens at its distal end was used to deliver laser energy to tumors in the hind leg (mean volume = 100 mm3). Two thermocouples were inserted into each tumor. One thermocouple controlled a microprocessor-driven hyperthermia program (maximum output of 3.5 Watts) to maintain the desired temperature. Tumors were exposed to various temperature-time combinations (42-45 degrees C/30 min). Our initial results indicated that excellent temperature control to within 0.2 degrees C of the desired temperature at the feedback thermocouple was achievable during both superficial and interstitial heat treatments. Temperatures at the second thermocouple, however, were found to be lower by as much as 2.3 degrees C (using the cylindrical diffusor) or higher by up to 4.6 degrees C (using the microlens) when compared to the feedback thermocouple temperature. Several correlations were seen between total dose, tumor growth delay, percent skin necrosis, and temperature at the second thermocouple after several superficial and interstitial treatments. Statistically significant improvements in tumor growth delay (at 42 and 45 degrees C) and increased percent skin necrosis at all temperatures were observed after superficial versus interstitial treatment.     

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.     

PSD-007介导的光动力疗法治疗小鼠骨肉瘤的实验研究

目的 观察光敏剂PSD-007对小鼠骨肉瘤细胞LM-8的体外及体内光动力效应.方法 PSD-007与LM-8细胞共同孵育后以激光照射,应用MTT法测定光密度(OD540)值,计算抑制率.40只C3H小鼠接种LM-8细胞,皮下瘤块直径7～8 mm时随机分为:(1)对照组,空白对照、生理盐水加光照、注射PSD-007不光照;(2)光动力治疗组,分别注射5mg/kg、10mg/kg PSD-007,6 h后以激光照射.1周后测量瘤体大小、重量,计算抑瘤率并行病理学检查.C3H小鼠30只建立肿瘤模型,肿瘤直径达10～12mm时,分别行肿瘤边缘切除无光动力治疗(对照组)、边缘切除后240 J/cm2光动力治疗及边缘切除后360 J/cm2光动力治疗.4周后比较肿瘤复发率.结果 体外只光照或只注射PSD-007对LM-8细胞均无杀伤作应.PSD-007浓度越高、激光照射强度越大,LM-8细胞OD540值越小.PSD-007浓度>4μg/ml,光照强度>6 J/cm2时,抑制率>50%.光镜下细胞形态呈坏死或凋亡样改变.体内实验显示光动力治疗组的肿瘤体积及瘤重均减小,肿瘤边缘切除高强度激光照射组的复发率较对照组低.结论 PSD-007对LM-8细胞有明确的光动力抑制效应,其作用大小取决于其浓度和激光照射强度.光动力疗法可以降低肿瘤边缘切除后的复发率.

Abstract：

Objective To evaluate the PSD-007-mediated photodynamic effect on mouse osteosarcoma cell line LM-8, both in vitro and in vivo. Methods LM-8 cells were incubated with different concentrations of PSD-007 for 4 hours and then followed different laser irradiations. After photodynamic therapy (PDT), cell viability was measured using MTT assay and the optical density in each experiment was measured at 450 nm with a micro plate reader. The inhibition rate of cell growth was calculated. Four-week-old female C3H mice were used for implantation of LM-8 cells. When the diameter of tumor reached up to 7-8 mm, the mice were randomly divided into following groups: 1) control group, including untreated control, saline with laser irradiation, PSD-007 without laser irradiation; 2) PDT group, PSD-007 (5 and 10 mg/kg) was injected intravenously into the mice, and the tumor site was irradiated with laser light 6 hours after injection. Seven days after PDT, the size and weight of the tumors were measured. The inhibition rate of tumor was calculated, and all tumor specimens were taken for pathologic examination. After the diameter of tumor was 10-12 mm, the tumors were performed a marginal resection and subsequently followed 3 different treatments: without PDT (control), PDT with 240 J/cm2 or 360 J/cm2 laser irradiation. After 4 weeks treatment, the tumor recurrence rates were analyzed. Results MTT assay revealed that the cytotoxic effect of PDT on the LM-8 cells was positively correlated with the concentration of PSD-007 and the level of laser irradiation. When the concentration exceeded 4μg/ml, and the energy exceeded 6 J/cm2, the inhibition ratio was over 50%. No anti-tumor effect was observed in the cells treated with only laser irradiation or PSD-007 injection. Compared with the control group, the size and weight of the tumors were obviously decreased after PDT. PDT performed after marginal resection of the tumor reduced the rate of local recurrence. Conclusion PDT with PSD-007 showed cytotoxic effect on the LM-8 cells, and which performed after marginal resection of the tumor reduced the rate of local recurrence.     

Enhanced antitumor effects of bleomycin and moderate hyperthermia by additional use of ethanol

The combined effects of moderate local hyperthermia, bleomycin and ethanol were investigated with Lewis lung carcinoma tumors in female C57BL/6 mice. Different combinations of treatments were performed on days 4 and 7 after tumor implantation. Combined treatment of 41 degrees C hyperthermia and bleomycin resulted in mild reductions of tumor growth. Hyperthermia plus bleomycin led to marked reduction in tumor growth under the condition of a 43 degrees C temperature. The antitumor effects of 41 degrees C hyperthermia combined with bleomycin were enhanced by the additional use of ethanol, and these effects were more remarkable than those of 43 degrees C hyperthermia and bleomycin. A possible application of these findings to clinical therapy for advanced esophageal cancer was discussed.     

Nd:YAG laser hyperthermia treatment of rat mammary adenocarcinoma in conjunction with surface cooling

Electromagnetic radiation ranging from radiofrequency to microwave has classically been used to induce hyperthermia for treatment of cancer. This paper presents a new technique using near infrared radiation from an Nd:YAG laser in conjunction with surface cooling to induce hyperthermia in a rat tumor model. A CW Nd:YAG laser hyperthermia system was used to induce hyperthermic temperatures in chemically (DMBA) induced rat mammary adenocarcinomas. The laser was interfaced to a computer and a thermometry unit that provided feedback to control the tumor temperature between 43.2-43.5 degrees C. A thermocouple was placed at the base of the tumor and its temperature was used to control laser exposure. All tumors were 10 to 20 mm in diameter. Surface cooling methods investigated included forced air flow from a fan, forced oxygen flow plus an IV drip, and forced moist oxygen flow from a nebulizer. Twelve rat mammary adenocarcinomas have been treated with Nd:YAG laser hyperthermia. In 4 treatments, no surface cooling was employed. In one treatment the surface was cooled using oxygen flow plus IV drip. In 7 treatments the skin was cooled using the nebulizer technique. The nebulization provided the most effective and reproducible surface cooling. Nd:YAG laser hyperthermia delivered in conjunction with nebulizer surface cooling produced efficient heating of rat mammary adenocarcinomas. A mean temperature of 42.1 degrees C was obtained at the base of the tumors while the mean surface temperature was 37.0 degrees C.     

Hyperthermia potentiates the effects of aluminum phthalocyanine tetrasulfonate-mediated photodynamic toxicity in human malignant and normal cell lines.

The purpose of this study was to examine the effects of photodynamic therapy utilizing aluminum phthalocyanine tetrasulfonate in vitro on several human malignant and normal cell types, with or without hyperthermia. Cells examined included normal skin fibroblasts, HT-1080 fibrosarcoma cells, SCC-25 (squamous cell carcinoma) and malignant melanoma cells. An argon-pumped continuous wave tunable dye laser at 675 nm was used as the light source, hyperthermia groups were heated to 42.5 degrees C, and radioisotope incorporation was used to measure DNA and protein synthesis as toxicity assays. Results showed an energy-dose, and A1PcS-concentration dependent toxicity in all cell lines examined, with moderate selectivity toward malignant cells. Hyperthermia alone was slightly toxic in melanomas and HT-1080 cell lines but had no effect in normal fibroblasts or SCC-25 cells. Hyperthermia synergistically potentiated the effects of PDT in all cell lines, and the combined modality was significantly more toxic in all malignant cell lines compared with normal cells. Thus, addition of hyperthermia to PDT protocols may enhance the efficacy of this treatment modality in vitro.     

Adriamycin enhanced in vitro and in vivo photodynamic therapy of mesothelioma.

The ability of Adriamycin (AD) to enhance the known in vitro and in vivo tumoricidal effects of photodynamic therapy (PDT) on the H-MESO-1 human malignant mesothelioma cell line was investigated. In vitro cytotoxicity was determined by incubating H-MESO-1 cells in microtiter plates (2 x 10(5) cells/well, 6 wells/group) with the photosensitizer Photofrin II (PF) and varying concentrations of AD (0, 2.5, 5.0, and 10.0 micrograms/ml) for 24 hr followed by exposure to gold vapor laser light (GVL) at a fluence of 6000 J/M2. [3H]Thymidine (1 microCi) was added to each well 24 hr after treatment. Cells were harvested and counted for thymidine incorporation 24 hr later. PDT alone resulted in a decrease in thymidine incorporation of 23% while the addition of AD to PDT at AD concentrations of 2.5, 5.0, and 10.0 micrograms/ml resulted in decreases of 62, 85, and 69%, respectively (P = 0.005) as compared to untreated controls. H-MESO-1 tumor bearing nude mice (n = 5) were injected ip with PF (5 mg/kg) and AD (5 mg/kg) 24 hr prior to illumination of the tumor site with GVL (120 J/cm2). Control groups (n = 5) received PDT, AD, and/or GVL alone. Tumor surface area was measured as the product of the greatest perpendicular dimensions every 5 days for 30 days. Administration of PDT without AD resulted in a decrease in tumor surface area of 50% on Day 10 with regrowth of tumor by Day 30 while AD alone with or without GVL had no impact on tumor growth.(ABSTRACT TRUNCATED AT 250 WORDS)     

An easy-to-use microwave hyperthermia system combined with spatially resolved MR temperature maps: phantom and animal studies

BACKGROUND: Hyperthermia has been used in multimodal cancer treatments, and in randomized, controlled studies, hyperthermia is an effective cancer therapy. For clinical accuracy and safety, however, temperature monitoring during treatment is essential. We aimed to develop a convenient microwave hyperthermia system combined with spatially resolved real-time temperature monitoring to improve its efficacy and safety. MATERIALS AND METHODS: Using an MR-compatible irradiation-type microwave applicator, agar phantoms, thigh muscles of rabbit, and subcutaneous VX2 tumors of rabbit were heated in combination with noninvasive MR temperature maps. For MR temperature calculation, a proton resonance frequency method was used. After determination of temperature coefficients and evaluation of the precision in MR thermometry, distribution of microwave heating over time was examined for each substance. RESULTS: The temperature coefficients of phantoms, rabbit muscles, and VX2 tumors were -0.00977, -0.00976, and -0.01027 ppm/ degrees C, respectively. The 95% limits of agreement of MR and fluoroptic thermometry in the three subjects were +0.318/-0.339 degrees C, +0.693/-0.661 degrees C, and +0.564/-0.526 degrees C, respectively. Concerning VX2 tumor, the average tumor temperature was 42.60 +/- 0.14 degrees C and the surface of skin was 43.27 +/- 0.45 degrees C in the 60-min experimental period. CONCLUSIONS: With this easy-to-use microwave hyperthermia system, effective hyperthermia was accomplished in phantoms and living animals in combination with MR temperature maps.     

Enhancing the antitumoral effect of hypericin-mediated photodynamic therapy by hyperthermia

BACKGROUND AND OBJECTIVES: In the previous study, we have found a synergistic effect on the RIF-1 tumor cell killing when hypericin-mediated photodynamic therapy (PDT) was combined with hyperthermia. The purpose of the present study was to investigate the antitumoral effect of hypericin-PDT in combination with hyperthermia in the RIF-1 mouse tumor model. STUDY DESIGN/MATERIALS AND METHODS: Tumor response to PDT in combination with hyperthermia was compared to the response to PDT or hyperthermia alone. To explore the possible mechanism involved in the interaction of PDT and hyperthermia, we determined the tumor cell survival by in vivo/in vitro cell survival assay and analyzed the functional blood vessels by Hoechst 33342 staining. The mode of cell death was examined by TUNEL assay. RESULTS: Enhanced tumor response was obtained by PDT immediately followed by hyperthermia. Tumor cell survival assay revealed that indirect vascular effect contributed greatly to the overall tumor cell death induced by PDT with hypericin, whereas direct tumor cytotoxicity played a major role in hyperthermia-induced tumor cell killing. Combining PDT with hyperthermia brought about a synergistic interaction on direct tumor cell killing. Even though PDT or hyperthermia alone induced severe blood vessel shutdown and the combined treatments led to significant potentiation of the vascular damage as examined by Hoechst staining, the gain in tumor cell death as a result of this secondary vascular effect was limited after the combined treatments. Following the cellular damage by PDT in combination with hyperthermia, tumor cells were triggered to undergo apoptosis. CONCLUSIONS: Our study demonstrated the possibility of using hyperthermia to potentiate the antitumoral effect of hypericin-mediated PDT.     

The effect of radiation therapy and hyperthermia on a human prostatic carcinoma cell line grown in athymic nude mice

The effect of radiation and/or hyperthermia on a human prostatic carcinoma xenograft in athymic nude mice was investigated. A human prostate carcinoma subline (1-LN-PC-3-1A) was inoculated subcutaneously in the thigh of male athymic nude mice. When tumors reached a size of approximately 200 mm.3, they were treated with either radiation (X) or hyperthermia (H) alone, or in combination (X + H). In the combined treatment, hyperthermia was delivered immediately after radiation exposure. Comparison of the time required to reach twice the tumor volume observed at the time of treatment was used to define therapeutic impact on tumor growth. The combined treatment resulted in median tumor volume doubling time of 35.5 days, compared to 18 days and 25.5 days, respectively, for hyperthermia or radiation alone. Analysis of tumor doubling time using a proportional hazards regression indicates that under the conditions of this experiment, the effect of radiation and hyperthermia for 1-LN-PC-3-1A tumors is additive. The impact of this treatment regimen in the management of prostatic cancer requires further investigation.     

The relationship of body temperatures to the efficacy of chemotherapy against systemic metastases from B16 melanoma

Potential synergy between physiologic levels of heat and chemotherapy was investigated in C57BL/6 mice bearing the B16 melanoma. Low levels of hyperthermia alone had no effect on the growth of the primary tumor but augmented the growth delay induced by cyclophosphamide. Although the addition of hyperthermia to chemotherapy and amputation increased the duration of survival and decreased the number of pulmonary metastases, heat did not increase the cure rate of animals with gross or microscopic pulmonary metastases. The incidence of local recurrence was decreased by hyperthermia in animals treated with chemotherapy and incomplete excision of the primary tumor.     

Photodynamic therapy of superficial bladder tumors

Photodynamic therapy (PDT), using hematoporphyrin derivative (HPD) and the red light (wavelength 630 nm) of an argon-dye laser as the source of excitation energy was performed on 46 patients with superficial bladder tumors. Two methods of laser irradiation, (1) focal PDT using a 400 micron quartz fiber through a cystourethroscope in 22 patients with superficial bladder tumors and (2) whole bladder wall total PDT using a motor-driven laser light scattering device in 24 patients with multifocal carcinoma in situ and/or dysplasia of bladder mucosa associated with multicentric concurrent superficial tumors, were used. The patients in (2) had been referred for total cystectomy, and 19 of these 24 patients had a history of several transurethral resections, hyperthermia and/or instillation therapy. HPD 2-4 mg/kg was i.v. injected 48 to 72 hours before PDT. Judging from the results of 60 protrusions treated by focal PDT, the light power should be 200 mW/cm2 for 5-10 minutes or more and the total light energy should be 100 J/cm2 or more in tumors up to 2 cm in size. With focal PDT, 4 of the 22 patients had no recurrence with the mean tumor free time of 20.8 months. In 6 of the 24 patients treated with total PDT using 10, 20 or 30 J/cm2 of light energy, there was no recurrence with a mean tumor-free time of 7.5 months and there was no significant relationship between the recurrence rate and total light energy used.     

Thermal sensitization through ROS modulation: a strategy to improve the efficacy of hyperthermic intraperitoneal chemotherapy

BACKGROUND: The purpose of this study was to investigate whether modulation of cellular reactive oxygen species (ROS) provides a synergistic effect with hyperthermia to induce tumor cell death in a colon cancer cell line. MATERIALS AND METHODS: HT-29 colon cancer cells were exposed to heat (43 degrees C) in the presence of the ROS-generating drug, 2-2'-azobis-(2-amidinopropane) dihydrochloride (AAPH) for 1 h. Viable cell mass and apoptosis was measured by MTT and annexin V staining, respectively. Oxidative stress was evaluated by DCFH fluorescence. Protein levels were determined by Western blot analysis. RESULTS: A synergistic effect on cell viability with AAPH was noted under hyperthermic conditions as compared with hyperthermia alone (P < .05). The number of nonviable cells after hyperthermia and AAPH exposure was also significantly increased compared with AAPH at 37 degrees C (42% vs 20%, P < .05). ROS levels were increased modestly with AAPH at 37 degrees C, whereas they increased significantly in a dose-dependent manner with AAPH at 43 degrees C. Transient increases of phosphorylated-p38 and ERK and decreases in phosphorylated-AKT were observed in the cells exposed to AAPH at 43 degrees C. Pretreatment of inhibitors of p38 yielded additional decreases in cell mass when used in combination with AAPH and hyperthermia (P < .05). Increased expression of HSP 27 observed at 43 degrees C was abrogated with AAPH exposure. CONCLUSIONS: Oxidative stress increased the cytotoxic effects of hyperthermia in colon cancer cells. Thermal sensitization through modulation of cellular ROS may represent a novel approach to increase the efficacy of hyperthermia as an anticancer modality.