Excised human neoplastic tissues are more sensitive to heat than the adjacent normal tissues

Improved tumour delivery of iron oxide nanoparticles for magnetic hyperthermia therapy of melanoma via ultrasound guidance and 111In SPECT quantification

Magnetic field hyperthermia relies on the intra-tumoural delivery of magnetic nanoparticles by interstitial injection, followed by their heating on exposure to a remotely-applied alternating magnetic field (AMF). This offers a potential sole or adjuvant route to treating drug-resistant tumours for which no alternatives are currently available. However, two challenges in nanoparticle delivery currently hinder the effective clinical translation of this technology: obtaining enough magnetic material within the tumour to enable sufficient heating; and doing this accurately to limit or avoid damage to surrounding healthy tissue. A further complication is the lack of established methods to non-invasively quantify nanoparticle biodistribution, which is necessary to evaluate the performance of improved delivery strategies. Here we employ 111In radiolabelling and single-photon emission computed tomography (SPECT) to non-invasively quantify distribution of a clinical grade iron-oxide-based nanoparticle in a mouse model of melanoma. We show that compared to manual injection, ultrasound guided delivery together with syringe-pump-controlled infusion improves both the nanoparticle concentration within the tumour, and the accuracy of delivery - reducing off-target peri-tumoural delivery. Following AMF heating, injected melanomas shrank significantly compared to non-injected controls, validating therapeutic efficacy. Systemic off-target delivery was quantified and extrapolated to predict off-target energy absorbance within safe limits for the main sites of background accumulation. With many nanoparticle-based therapies currently in development for cancer, this image-guided delivery strategy has wide potential impact beyond the field of magnetic hyperthermia. Future use in representative patient cohorts would also be enabled by the high clinical availability of both SPECT and ultrasound imaging.

Percutaneous radiofrequency ablation near large vessels in beagle livers: the impact of time and distance on the ablation zone

PURPOSE

To investigate the effects of ablation time and distance between the radiofrequency ablation (RFA) electrode tip and a large vessel on the ablation zone in beagle livers.

METHODS

Sixty-one percutaneous RFA coagulation zones were created near large vessels in 10 beagle livers in vivo. The ablated lesions were divided into four groups based on ablation time and distance between the electrode tip and a large vessel (group A, 3 min 0.5 cm; group B, 3 min 0 cm; group C, 5 min 0.5 cm; group D, 5 min 0 cm). The ablated area, long-axis diameters, short-axis diameters, and vessel wall injury were examined.

RESULTS

With a fixed ablation time, the ablation zone created with the electrode tip at 0.5 cm from the large vessel was significantly larger than at 0 cm (p < .05). At a fixed distance between the electrode tip and vessel, the ablation zone created for 5 min was significantly larger than for 3 min (p < .05). The frequency of vessel wall injury in the 0 cm groups was significantly higher than that in the 0.5 cm groups (37.5% vs. 6.9%; p = .003, odds ratio, 7.43). The ratio of width to depth (Dw/Dz) was larger in the 0.5 cm groups than in the 0 cm groups (p < .001).

CONCLUSION

The ablation zone increased with longer ablation times and greater distances between the RFA tip and large vessels for perivascular lesions. The distance between the needle tip and blood vessels is an important factor that affects the overall ablation outcome.

Preoperative Hyperthermia Combined with Chemotherapy and Irradiation for the Treatment of Patients with Esophageal Carcinoma

Aims and Background

The purpose of this study was to investigate the combined effects of hyperthermia, chemotherapy and irradiation on esophageal cancer.

Methods and material

Since 1978, we have clinically applied hyperthermia combined with chemotherapy and irradiation (HCR therapy), to patients with carcinoma of the esophagus. The clinical results of 136 patients receiving preoperative HCR therapy were then compared with those of 107 cases undergoing preoperative chemo-radiotherapy (CR).

Results

A histological examination of the resected esophagus after preoperative treatment revealed that 65.4% and 50.5% of the patients responded markedly (no viable cancer cells) and moderately (more than two thirds of all cancer cells destroyed) to HCR and CR therapies, respectively (p <0.05). The five-year survival rates were 22.3% and 13.7% in the HCR and CR groups, respectively, and the difference was statistically significant (p <0.01). In particular, for the patients classified as TNM Stages III and IV, a significantly longer survival period was obtained with HCR therapy (p <0.05). In addition, no severe side effects were encountered in the patients given just hyperthermia.

Conclusion

Our clinical results suggest that preoperative hyperthermo-chemo-radiotherapy shows great promise for treatment of patients with advanced carcinoma of the esophagus.

Comparison of iron oxide nanoparticle and microwave hyperthermia alone or combined with cisplatinum in murine breast tumors

Surgery, radiation and chemotherapy are currently the most commonly used cancer therapies. Hyperthermia has been shown to work effectively with radiation and chemotherapy cancer treatments. The major obstacle faced by previous hyperthermia techniques has been the inability to deliver heat to the tumor in a precise manner. The ability to deliver cytotoxic hyperthermia to tumors (from within individual cells) via iron oxide magnetic nanoparticles (mNP) is a promising new technology that has the ability to greatly improve the therapeutic ratio of hyperthermia as an individual modality and as an adjuvant therapy in combination with other modalities. Although the parameters have yet to be conclusively defined, preliminary data suggests mNP hyperthermia can achieve greater cytotoxicity (in vitro) than conventional water bath hyperthermia methods. At this time, our theory is that intracellular nanoparticle heating is more effective in achieving the combined effect than extracellular heating techniques.1 However, understanding the importance of mNP association and uptake is critical in understanding the potential novelty of the heating modality. Our preliminary data suggests that the mNP heating technique, which did not provide time for particle uptake by the cells, resulted in similar efficacy to microwave hyperthermia. mNP hyperthermia/cisplatinum results have shown a tumor growth delay greater than either modality alone at comparable doses.

METHODS

One hour before nanoparticle hyperthermia, CDDP chemotherapy (5mg/kg of body mass) was delivered intraperitoneally (IP). Iron oxide nanoparticles, 7.5mg of iron per gram of tumor, were injected into MTGB flank tumors in female C3H mice immediately before activation. A 170 KHz, 400-450 Oe alternating magnetic field (AMF) was used to induce particle heating. A comparison of nanoparticle induced hyperthermia to non-nanoparticle induced hyperthermia was also made using a 915 MHz microwave generator. Treatment duration was determined by the use of the cumulative equivalent minutes (CEM) algorithm. A CEM 60 was selected as the thermal dose for all experimental groups.

RESULTS

1) Preliminary mNP hyperthermia/cisplatinum results have shown a tumor growth delay greater than either modality alone at comparable doses. 2) mNP hyperthermia delivered 10 minutes post mNP injection and microwave hyperthermia, with the same thermal dose, demonstrate similar treatment efficacy.

Transcranial electro-hyperthermia combined with alkylating chemotherapy in patients with relapsed high-grade gliomas: phase I clinical results

Non-invasive loco-regional electro-hyperthermia (EHT) plus alkylating chemotherapy is occasionally used as salvage treatment in the relapse of patients with high-grade gliomas. Experimental data and retrospective studies suggest potential effects. However, no prospective clinical results are available. We performed a single-center prospective non-controlled single-arm Phase I trial. Main inclusion criteria were recurrent high-grade glioma WHO Grade III or IV, age 18-70, and Karnofsky performance score > or = 70. Primary endpoints were dose-limiting toxicities (DLT) and maximum tolerated dose (MTD) with the combined regimen. Groups of 3 or 4 patients were treated 2-5 times a week in a dose-escalation scheme with EHT. Alkylating chemotherapy (ACNU, nimustin) was administered at a dose of 90 mg/m(2) on day 1 of 42 days for up to six cycles or until tumor progression (PD) or DLT occurred. Fifteen patients with high-grade gliomas were included. Relevant toxicities were local pain and increased focal neurological signs or intracranial pressure. No DLT occurred. In some patients, the administration of mannitol during EHT or long-term use of corticosteroids was necessary to resolve symptoms. Although some patients showed responses in their primarily treated sites, the pattern of response was not well defined. EHT plus alkylating chemotherapy is tolerable in patients with relapse of high-grade gliomas. Episodes of intracranial pressure were, at least, possibly attributed to EHT but did not cause DLTs. A Phase II trial targeting treatment effects is warranted on the basis of the results raised in this trial.

Large-volume multi-tined expandable RF ablation in pig livers: comparison of 2D and volumetric measurements of the ablation zone

OBJECTIVES

To compare two-dimensional (2D) and three-dimensional (3D) computed tomography (CT) measurements of ablation zones (AZs) related to the shaft of two different large-volume monopolar multi-tined expandable electrodes.

METHODS

Percutaneous radiofrequency (RF) ablation was performed in 12 pigs (81.6 +/- 7.8 kg) using two electrodes (LeVeen 5 cm, Rita XL 5 cm; n = 6 in each group). Contrast-enhanced CT with the electrode shaft in place evaluated the AZ. The largest sphere centred on the electrode shaft within the AZ was calculated (1) based on the 2D axial CT image in the plane of the shaft assuming rotational symmetry of the AZ and (2) using prototype software and the 3D volume data of the AZ measured with CT.

RESULTS

The mean largest diameter of a sphere centred on the electrode shaft was always smaller using the 3D data of the AZ than using 2D CT measurements assuming rotational symmetry of the AZ (3D vs 2D): LeVeen 18.2 +/- 4.8 mm; 24.5 +/- 3.1 mm; p = 0.001; Rita XL 20.0 +/- 3.7 mm; 28.8 +/- 4.9 mm; p = 0.0002. All AZ showed indentations around the tines.

CONCLUSIONS

Two-dimensional CT measurements assuming rotational symmetry of the AZ overestimate the largest ablated sphere centred on the electrode shaft compared with 3D CT measurements.

Experimental Radiofrequency Ablation Near the Portal and the Hepatic Veins in Pigs: Differences in Efficacy of a Monopolar Ablation System

BACKGROUND

We sought to compare the efficacy of a monopolar radiofrequency ablation system in vivo near the portal vein and the hepatic veins in porcine liver.

MATERIALS AND METHODS

Radiofrequency ablation of healthy livers near the portal vein and the hepatic veins was performed in 10 pigs with a multitined expandable electrode. Volumes and diameters of zones of ablation were assessed by magnetic resonance imaging.

RESULTS

Volumes (16.0 +/- 5.5 mL, P = 0.001) and diameters (4.0 +/- 0.7 cm, 3.3 +/- 0.7 cm, 3.0 +/- 0.6 cm, P <or= 0.05) of the zones of ablation near the hepatic veins were larger than that near the portal vein (7.5 +/- 4.1 mL, 3.2 +/- 0.7 cm, 2.6 +/- 0.7 cm, 2.4 +/- 0.6 cm). Energy deposition needed to ablate liver tissue was higher (P = 0.003) for radiofrequency ablation near the portal vein (3.16 +/- 1.58 kJ/mL) than for radiofrequency ablation near the hepatic veins (1.65 +/- 1.14 kJ/mL).

CONCLUSIONS

Higher energy deposition is needed to ablate liver tissue near the portal vein than near the hepatic veins. As a result, the zone of ablation is larger near the hepatic vein than near the portal vein.

Radiofrequency ablation: in vivo comparison of four commercially available devices in pig livers

PURPOSE

To compare in vivo coagulation necrosis obtained with four radiofrequency (RF) ablation devices, to determine shape and reproducibility of induced coagulation by means of three-dimensional measurements of the ablation zone, and to achieve representations of the coagulated areas in three-dimensional spaces.

MATERIALS AND METHODS

Four commercially available RF devices (perfusion, internally cooled cluster, and nine- and 12-tine expandable electrodes) that represent the most widely used systems on the market were tested. Sixteen in vivo ablation procedures were performed in porcine livers (four ablations for each RF system). After macroscopic and histopathologic analyses of 3-mm-thick liver sections, morphometric and volumetric findings in the central zone of white coagulation necrosis were assessed. Coagulation volume, diameter, length, and shape were determined digitally. After analysis of variance, measurements with each system were tested with the Tukey post hoc test.

RESULTS

Mean coagulation volumes were 31.5 cm3 +/- 15.8 (SD) for the perfusion electrode, 20.5 cm3 +/- 2.6 for the cluster electrode, 16.2 cm3 +/- 7.3 for the 12-tine electrode, and 9.8 cm3 +/- 3.2 for the nine-tine electrode (P <.05, perfusion vs nine-tine electrode). No significant differences were observed regarding the mean short axis perpendicular to the needle shaft: 2.30 cm +/- 0.94, 3.04 cm +/- 0.26, 3.44 cm +/- 0.21, and 2.70 cm +/- 0.76, respectively. Variation coefficients were 0.50, 0.13, 0.45, and 0.33, respectively.

CONCLUSION

Larger coagulation volumes were obtained with the perfusion and internally cooled cluster devices. More spherical volumes of ablation were achieved with the 12-tine and cluster electrodes. The former proved superior with regard to the short axis perpendicular to the needle shaft. The cluster and nine-tine electrode produced better reproducibility, which is suggestive of improved predictability of the extent of coagulation with these systems.

Effect of vascular occlusion on radiofrequency ablation of the liver: results in a porcine model

OBJECTIVE

This study determined the effect of vascular occlusion on radiofrequency lesion shape, volume, and temperature in a porcine liver model.

SUBJECTS AND METHODS

Radiofrequency lesions (n = 33) were created in the livers of six domestic pigs in vivo using a multiprong radiofrequency electrode. Lesions were randomly assigned to one of four vascular occlusion groups: portal vein, hepatic artery, Pringle maneuver (both hepatic artery and portal vein), or no occlusion. Radiofrequency parameters were time, 7 min; power, 50 W; and target temperature, 100 degrees C. Temperatures were measured 5, 10, and 15 mm from the electrode. After the animals were sacrificed, the lesions were excised. Lesion volume, diameter, and shape; maximum temperature; and time exposed to lethal temperatures (42-60 degrees C) were determined.

RESULTS

Lesion volume was greatest with the Pringle maneuver lesions (12.6 +/- 4.8 cm(3)), followed by occlusion of the portal vein (8.6 +/- 3.8 cm(3)), occlusion of the hepatic artery (7.6 +/- 2.9 cm(3)), and no occlusion (4.3 +/- 1.0 cm(3)) (p < 0.05). Maximum lesion diameter was similar with the Pringle maneuver (3.3 +/- 0.3 cm), the portal vein (3.3 +/- 0.2 cm), and the hepatic artery (3.2 +/- 0.2 cm) groups compared with no occlusion (2.6 +/- 1.0 cm) (p < 0.05). Minimum lesion diameter ranged from 2.9 cm for Pringle maneuver lesions to 1.0 cm for lesions with no occlusion (p < 0.05). Vascular occlusion increased the time tissue was exposed to lethal temperatures (> 42-60 degrees C) and created more spherical lesions than no occlusion.

CONCLUSION

Vascular occlusion combined with radiofrequency ablation increases the volume of necrosis, creates a more spherical lesion, and increases the time tissue is exposed to lethal temperatures when compared with radiofrequency alone. Most of this vascular occlusion effect could be accomplished with hepatic artery occlusion alone.

Laser-induced thermotherapy combined with hepatic arterial embolization in the treatment of liver tumors in a rat tumor model

OBJECTIVE

To assess the effect of combined laser-induced thermotherapy (LITT) and hepatic arterial embolization with degradable starch microspheres (DSM) on tumor response and intrahepatic temperature distribution in rats with liver tumors.

SUMMARY BACKGROUND DATA

Laser-induced thermotherapy is a promising in situ ablation technique for malignant liver tumors. However, clinical use is still limited, mainly because of the small size of the inducible coagulation necroses. This results in insufficient tumor destruction.

METHODS

Colon carcinoma CC531 was implanted in 60 WAG rat livers. Fourteen days later, a silicon catheter was implanted in the hepatic artery for DSM administration. Tumors were exposed to 1064 nm Nd:YAG laser light at 2 watts for 10 minutes from a diffuser tip applicator placed in the tumor. The animals were randomized into a sham-operated control (group I) and three test groups. Group II received DSM alone, group III received LITT alone, and group IV received DSM + LITT. Tumor control was examined 1, 7, and 14 days after treatment.

RESULTS

A complete tumor remission was achieved in all rats treated with LITT + DSM (group IV). In contrast, tumor progression was seen in animals treated with LITT alone (group III) or DSM alone (group II), as well as in the sham-operated controls (group I).

CONCLUSIONS

The authors' results suggest that the combination of LITT and DSM considerably increases the efficacy of LITT in the treatment of liver metastases in the rat.

Malignant lymphoma of the rectum treated preoperatively with hyperthermia and radiation

A 58-year-old Japanese woman with primary malignant lymphoma of the rectum was treated preoperatively with radiation and intraluminal hyperthermia, after which abdominoperineal rectal amputation (Miles' operation) was done. The rectal tumor disappeared and there were no lymphoma cells in the resected specimens. The postoperative course was smooth and she is being followed in the outpatient department. At this writing, five years after the surgery, she remains well.

Predictive value of intracellular ATP level for cell viability after heating in malignant cells

An adenosine triphosphate (ATP) assay is known to be a useful chemosensitivity test, which correctly reflects cell viability. We investigated the usefulness of ATP assay as a thermosensitivity test by comparing two world-wide accepted assays which included a succinate dehydrogenase (SD) assay and a colony assay. We exposed KSE-1 and KSE-2 cell lines to various degrees of hyperthermia at 42, 43 and 44 degrees C for 0.5, 1, 2, 3 and 4 h, respectively. The ATP activity for the KSE-1 and KSE-2 cell lines was 2.0 and 0.7% in change of cell viability after heating at 44 degrees C for 4 h, respectively. Colony formation rates in the KSE-1 and KSE-2 cell lines were 0.9 and 0%, respectively, whereas the SD activity of each cell line was 24.1 and 22.8%. As a whole, the ATP assay showed a closer correlation to the colony assay than the SD assay because the latter revealed a more than 20% pseudo-viability due to the response between the base and residual enzyme even after the cells had died. Thus, the ATP assay was judged to be more sensitive than the SD assay; it was also quicker than the colony assay in evaluating cell viability after heating. We propose that the ATP assay should be included as another useful thermosensitivity test for malignant cells.

5-Fluorouracil's cytotoxicity is enhanced both in vitro and in vivo by concomitant treatment with hyperthermia and dipyridamole

We obtained evidence that the cytotoxic effect of 5-fluorouracil (5-FU) is augmented when the drug is given in combination with hyperthermia (HYP) and dipyridamole (DP). Nontoxic levels of DP enhanced the combined cytotoxicity of 5-FU and HYP against B16 melanoma and human tumor cells in vitro as measured by the succinate dehydrogenase inhibition (SDI) test. Growth of B16 melanoma that had been subcutaneously implanted into the feet of C57 BL mice was inhibited by treatment with the combinations of 5-FU and HYP, of 5-FU and DP, and of 5-FU, HYP and DP as compared with the administration of 5-FU alone. Treatment with HYP plus DP did not alter the body weight of mice that received 5-FU. The administration of DP plus HYP seemed to render the tumor cells more sensitive to 5-FU. The combination of 5-FU, HYP and DP shows promise for the treatment of patients suffering from malignant disease.

Sensitivity to heat and radiation of human rectal malignant tissues in vitro

The sensitivity to heat and radiation of 22 rectal cancer tissues obtained at biopsy was studied using the in vitro succinate dehydrogenase inhibition test. The succinate dehydrogenase activity of tissue fragments was assayed after exposure at 43 degrees C (hyperthermia) for 20 hours, to radiation of 6 Gy, and to both heat (43 degrees C) and radiation (6 Gy). The sensitivity to each treatment was estimated by the percentage of succinate dehydrogenase activity of the treated cells compared with that of control cells. The mean plus or minus standard deviation of succinate dehydrogenase activity after exposure to radiation, heat, and both heat and radiation, was 84.7 +/- 12.6 percent, 52.9 +/- 20.7 percent, and 46.8 +/- 20.7 percent, respectively. The succinate dehydrogenase activities of heat-treated cells and both heat- and radiation-treated cells were significantly lower than that of the radiation-treated cells (P less than 0.01). The succinate dehydrogenase activities of heat plus radiation treated cells were the lowest in tissues from cancer lesions. Although the number was small, there was a correlation between this test and clinical outcome in seven of nine cases. Thus, preoperative therapy of hyperthermia plus radiotherapy is expected to be effective for treating patients with rectal cancer.

Azo-dye-induced primary hepatoma and a gradual increase in thermosensitivity

To determine whether or not the cytotoxic effects of hyperthermia are directed primarily to malignant cells, we examined changes in thermosensitivity during hepatocarcinogenesis in rats, as induced by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). The findings were compared with those in livers of rats fed a commercial diet. The cell viability was determined using the succinate dehydrogenase inhibition (SDI) test. The succinate dehydrogenase (SD) activity of liver cells, when exposed to heat (43 degrees C) for 2, 5, or 10 hr, decreased in a time-dependent manner, in each tissue. The decrease in SD activity was evident in 3'-Me-DAB liver for 5 hr of heat treatment on day 57, compared with findings in the normal liver. Significant differences were present for 2, 5, and 10 hr on days 93 and 136. Thus a chemically induced hepatoma is more sensitive to heat than are the normal cells. As this thermosensitivity gradually increased during the hepatocarcinogenesis, the malignant cells are particularly vulnerable to hyperthermia.

Sarcoma-180 cells are more sensitive to heat than are mouse normal tissues: esophagus, stomach, small intestine, large intestine, liver, spleen, and kidney

Sensitivity of various mouse tissues to heat was determined using mouse sarcoma-180 (S-180) cells and normal tissues: esophagus, stomach, small intestine, large intestine, liver, spleen, and kidney. The in vitro succinate dehydrogenase inhibition (SDI) test was used. The succinate dehydrogenase (SD) activity of tissue fragments was assayed, following exposure to a temperature of 43 degrees C (heat treatment) or 37 degrees C (control) for 1, 2, 5, or 10 hr. The sensitivity to heat treatment was estimated by the percentage of SD activity of the heat-treated cells, compared to that of the control cells. The decrease in SD activity following exposure to heat varied with the tissue. The SD activity decreased to a greater extent in the S-180 cells than in the normal tissues. In the normal tissues, the order of sensitivity to heat was stomach, spleen, large intestine, small intestine, esophagus, kidney and liver. These results show that hyperthermia is tissue selective, hence heat treatment of a malignant lesion should be carefully designed.