Phase I clinical trial of melphalan and 41.8 degrees C whole-body hyperthermia in cancer patients

Systematic review about complementary medical hyperthermia in oncology

Hyperthermia is a generic term for different techniques using heat in cancer therapies. Temperatures of about 42° Celsius in combination with chemo- or radiotherapy may improve the effectiveness of those treatments. Clinical benefit is shown in “standard hyperthermia” with tumour temperatures assessed during treatment. This systematic review thoroughly assesses the state of evidence concerning the benefits and side effects of electro hyperthermia or whole-body hyperthermia (“alternative hyperthermia”) in oncology. From 26 April 2021 to 09 May 2021, a systematic search was conducted searching five electronic databases (Embase, Cochrane, PsycINFO, CINAHL and Medline) to find studies concerning the use, effectiveness and potential harm of alternative medical hyperthermia therapy on cancer patients. From all 47,388 search results, 53 publications concerning 53 studies with 2006 patients were included in this systematic review. The patients were diagnosed with different types of cancer. The hyperthermic methods included whole-body hyperthermia (WBH) with different methods and electro hyperthermia (EH). The majority of the included studies were single-arm studies, counting in total 32 studies. Six studies were randomized controlled trials (RCT). In addition, one systematic review (SR) was found. The most critical endpoints were tumour response, survival data, pain relief, myelosuppression and toxicities. Outcome was heterogeneous, and considering the methodological limitations, clinical evidence for the benefit of alternative hyperthermia in cancer patients is lacking. Neither for whole-body hyperthermia nor for electro hyperthermia there is any evidence with respect to improvement of survival or quality of life in cancer patients.

Modulated Electro-Hyperthermic (mEHT) Treatment in the Therapy of Inoperable Pancreatic Cancer Patients-A Single-Center Case-Control Study

Our present oncological treatment arsenal has limited treatment options for pancreatic ductal adenocarcinoma (PDAC). Extended reviews have shown the benefits of hyperthermia for PDAC, supporting the perspectives with the improvements of the treatment possibilities. METHODS: A retrospective single-center case-control study was conducted with the inclusion of 78 inoperable PDAC patients. Age-, sex-, chemotherapy-, stage-, and ascites formation-matched patients were assigned to two equal groups based on the application of modulated electro-hyperthermia (mEHT). The EHY2030 mEHT device was used. RESULTS: A trend in favor of mEHT was found in overall survival (p = 0.1420). To further evaluate the potential beneficial effects of mEHT, the presence of distant metastasis or ascites in the patients’ oncological history was investigated. Of note, mEHT treatment had a favorable effect on patients’ overall survival in metastatic disease (p = 0.0154), while less abdominal fluid responded to the mEHT treatment in a more efficient way (p ≤ 0.0138). CONCLUSION: mEHT treatment was associated with improved overall survival in PDAC in our single-center retrospective case-control study. The outcome measures encourage us to design a randomized prospective clinical study to further confirm the efficiency of mEHT in this patient cohort.

Evidence based tools to improve efficiency of currently administered oncotherapies for tumors of the hepatopancreatobiliary system

Hepatopancreatobiliary tumors are challenging to treat, and the advanced or metastatic forms have a very low 5-year survival rate. Several drug combinations have been tested, and new therapeutic approaches have been introduced in the last decades, including radiofrequency and heat based methods. Hyperthermia is the artificial heating of tumors by various biophysical methods that may possess immunostimulant, tumoricidal, and chemoradiotherapy sensitizer effects. Both whole-body and regional hyperthermia studies have been conducted since the 1980s after the introduction of deep-seated tumor hyperthermia techniques. Results of the effects of hyperthermia in hepatocellular and pancreatic cancer are known from several studies. Hyperthermia in biliary cancers is a less investigated area. High local and overall responses to treatment, increased progression-free and overall survival, and improved laboratory and quality-of-life results are associated with hyperthermia in all three tumor types. With the evolution of chemotherapeutic agents and the introduction of newer techniques, the combination of adjuvant hyperthermia with those therapies is advantageous and has not been associated with an increase in alarming adverse effects. However, despite the many positive effects of hyperthermia, its use is still only known at the experimental level, and its concomitant utilization in routine cancer treatment is not certain because of the lack of thorough clinical studies.

Whole-body hyperthermia in combination with systemic therapy in advanced solid malignancies

Whole-body hyperthermia (WBH) might be beneficial for patients with metastasized solid malignancies when combined with systemic therapy. This review identified and summarized the phase I/II studies (n = 13/14) conducted using this combination of therapies. Most of the phase II studies used radiant heating methods in a thermal dose of 41.8 °C (1 h). All studies used classic chemotherapy. Great inter-study heterogeneity was observed regarding treatment regimes, included patients and reported response rates (12-89%). Ovarian cancer, colorectal adenocarcinoma, lung cancer and sarcoma have been studied most. Most reported toxicity (grade 3/4) was myelosuppression. Treatment related mortality was present (4 patients) in three out 14 phase II studies (350 evaluable patients, over 966 cycles of WBH with chemotherapy). Absence of phase III trials makes the additive value of WBH highly speculative. As modern oncology offers many less invasive treatments options, it is unlikely WBH will ever find its way in routine clinical care.

Magnetic hyperthermia enhance the treatment efficacy of peri-implant osteomyelitis

BACKGROUND

When bacteria colony persist within a biofilm, suitable drugs are not yet available for the eradication of biofilm-producing bacteria. The aim of this study is to study the effect of magnetic nano-particles-induced hyperthermia on destroying biofilm and promoting bactericidal effects of antibiotics in the treatment of osteomyelitis.

METHODS

Sixty 12-weeks-old male Wistar rats were used. A metallic 18G needle was implanted into the bone marrow cavity of distal femur after the injection of Methicillin-sensitive Staphylococcus aureus (MSSA). All animals were divided into 5 different treatment modalities. The microbiological evaluation, scanning electron microscope examination, radiographic examination and then micro-CT evaluation of peri-implant bone resorption were analyzed.

RESULTS

The pathomorphological characteristics of biofilm formation were completed after 40-days induction of osteomyelitis. The inserted implants can be heated upto 75 °C by magnetic heating without any significant thermal damage on the surrounding tissue. We also demonstrated that systemic administration of vancomycin [VC (i.m.)] could not eradicate the bacteria; but, local administration of vancomycin into the femoral canal and the presence of magnetic nanoparticles hyperthermia did enhance the eradication of bacteria in a biofilm-based colony. In these two groups, the percent bone volume (BV/TV: %) was significantly higher than that of the positive control.

CONCLUSIONS

For the treatment of chronic osteomyelitis, we developed a new modality to improve antibiotic efficacy; the protection effect of biofilms on bacteria could be destroyed by magnetic nanoparticles-induced hyperthermia and therapeutic effect of systemic antibiotics could be enhanced.

Trastuzumab-decorated nanoparticles for in vitro and in vivo tumor-targeting hyperthermia of HER2+ breast cancer

In this study, a magnetic core–shell modified tumor-targeting nanocarrier (MNPs-PEG–TRA) was engineered and demonstrated for the efficientin vitroandin vivohyperthermia treatment of breast cancer.

Magnetic particle hyperthermia--a promising tumour therapy?

We present a critical review of the state of the art of magnetic particle hyperthermia (MPH) as a minimal invasive tumour therapy. Magnetic principles of heating mechanisms are discussed with respect to the optimum choice of nanoparticle properties. In particular, the relation between superparamagnetic and ferrimagnetic single domain nanoparticles is clarified in order to choose the appropriate particle size distribution and the role of particle mobility for the relaxation path is discussed. Knowledge of the effect of particle properties for achieving high specific heating power provides necessary guidelines for development of nanoparticles tailored for tumour therapy. Nanoscale heat transfer processes are discussed with respect to the achievable temperature increase in cancer cells. The need to realize a well-controlled temperature distribution in tumour tissue represents the most serious problem of MPH, at present. Visionary concepts of particle administration, in particular by means of antibody targeting, are far from clinical practice, yet. On the basis of current knowledge of treating cancer by thermal damaging, this article elucidates possibilities, prospects, and challenges for establishment of MPH as a standard medical procedure.

Neuroprotective effects of cerebrolysin, a combination of different active fragments of neurotrophic factors and peptides on the whole body hyperthermia-induced neurotoxicity: modulatory roles of co-morbidity factors and nanoparticle intoxication

Military personals are often exposed to adverse environmental circumstances, for example, heat stress during peacekeeping or combat operations in summer months or in desert areas leading to disturbed mental functions. The suitable therapeutic strategies to treat heat-induced mental anomalies are still not worked out. Thus, exploration of suitable therapeutic strategies to minimize heat-induced abnormal brain function is needed in suitable animal models. Previous works from our laboratory show that rats exposed to whole body hyperthermia (WBH) for 4 h at 38 °C exhibited profound neuronal, glial, and axonal damages in the cerebral cortex, hippocampus, cerebellum, thalamus, and hypothalamus in a specific manner at light microscopy. Electron microscopy further revealed endothelial cell membrane damage, that is, breakdown of the blood-brain barrier (BBB) after WBH in the brain areas showing cellular damages. These observations indicate that breakdown of the BBB is instrumental in hyperthermia-induced brain injury. Pretreatment with cerebrolysin (2.5 ml or 5 ml/kg, i.v. 30 min before WBH), a mixture of various neurotropic factors and active peptide fragments significantly attenuated BBB disruption and brain damage following heat exposure in a dose-dependent manner. Furthermore, repeated administration of cerebrolysin (5 ml/kg, i.v.) starting from 30 min to 1h after but not after 1.5 or 2 h WBH markedly reduced the BBB disruption and neurotoxicity. Taken together our observations suggest that cerebrolysin if administered within 1 h after WBH in suitable doses induce marked reduction in neurotoxicity. This indicated that cerebrolysin has potential therapeutic value to treat heat stress victims to prevent mental dysfunction in future clinical settings.

Role of tumor vascular architecture in drug delivery

Tumor targeted drug delivery has the potential to improve cancer care by reducing non-target toxicities and increasing the efficacy of a drug. Tumor targeted delivery of a drug from the systemic circulation, however, requires a thorough understanding of tumor pathophysiology. A growing or receding (under the impact of therapy) tumor represents a dynamic environment with changes in its angiogenic status, cell mass, and extracellular matrix composition. An appreciation of the salient characteristics of tumor vascular architecture and the unique biochemical markers that may be used for targeting drug therapy is important to overcome barriers to tumor drug therapy and to facilitate targeted drug delivery. This review discusses the unique aspects of tumor vascular architecture that need to be overcome or exploited for tumor targeted drug delivery.

Hyperthermia, cisplatin and radiation trimodality treatment: a promising cancer treatment? A review from preclinical studies to clinical application

This review discusses available clinical and experimental data and the underlying mechanisms involved in trimodality treatment consisting of hyperthermia, cisplatin and radiotherapy. The results of phase I/II clinical trials show that trimodality treatment is effective and feasible in various cancer types and sites with tolerable toxicity. Based on these results, phase III trials have been launched to investigate whether significant differences in treatment outcome exist between trimodality and standard treatment. In view of the clinical interest, it is surprising to find so few preclinical studies on trimodality treatment. Although little information is available on the doses of the modalities and the treatment sequence resulting in the largest degree of synergistic interaction, the results from in vivo and in vitro preclinical studies support the use of trimodality treatment for cancer patients. Animal studies show an improvement in treatment outcome after trimodality treatment compared with mono- and bimodality treatment. Studies in different human tumour cell lines show that a synergistic interaction can be obtained between hyperthermia, cisplatin and radiation and that this interaction is more likely to occur in cell lines which are more sensitive to cisplatin.

Comparison of the anti-tumor effects of various whole-body hyperthermia protocols: correlation with HSP 70 expression and composition of splenic lymphocytes

Whole-body hyperthermia (WBH) has been used as an adjunct approach to radio-/ chemotherapy for tumor therapy for many years. However, the molecular mechanism underlying the enhancement of tumor control is not clearly understood. It has been hypothesized that WBH might activate immune system by inducing the expression of heat shock proteins (HSPs), which are thought to facilitate the presentation of tumor-specific antigens. In the present work, we examined the effects of various thermal doses of WBH on tumor growth delay and HSP70 levels in tumors on C57BL/6 mice, as well as on splenic lymphocyte subpopulations. The maximal WBH effect (about 40% decrease in tumor weight) was achieved by a 2-hour WBH treatment everyday at 40.0 degrees C. By using this treatment schedule, the populations of CD3+/CD4+ T cells and CD3+/CD8+ T cells increased by 4 and 3 times, respectively, at the end of WBH treatment period. When the length of day-by-day WBH treatment was longer than 2 hours or the frequency of WBH treatment was lower than once a day, the effect of tumor growth delay and the population of CD3+ T lymphocyte in spleen increase were discounted. On the other hand, the HSP70 levels in tumor nodules rose continuously as the WBH treating time increased, but the populations of NK cells in spleen did not change significantly. The results suggest that an increased CD3+ T lymphocyte population is closely related to the anti-tumor effect of WBH, which might be a useful marker for effectiveness of hyperthermia. However, neither the levels of HSP70 nor the NK cell populations in spleen appear to correlate to tumor control.

Exercising in Environmental Extremes

Athletes, military personnel, fire fighters, mountaineers and astronauts may be required to perform in environmental extremes (e.g. heat, cold, high altitude and microgravity). Exercising in hot versus thermoneutral conditions (where core temperature is > or = 1 degrees C higher in hot conditions) augments circulating stress hormones, catecholamines and cytokines with associated increases in circulating leukocytes. Studies that have clamped the rise in core temperature during exercise (by exercising in cool water) demonstrate a large contribution of the rise in core temperature in the leukocytosis and cytokinaemia of exercise. However, with the exception of lowered stimulated lymphocyte responses after exercise in the heat, and in exertional heat illness patients (core temperature > 40 degrees C), recent laboratory studies show a limited effect of exercise in the heat on neutrophil function, monocyte function, natural killer cell activity and mucosal immunity. Therefore, most of the available evidence does not support the contention that exercising in the heat poses a greater threat to immune function (vs thermoneutral conditions). From a critical standpoint, due to ethical committee restrictions, most laboratory studies have evoked modest core temperature responses (< 39 degrees C). Given that core temperature during exercise in the field often exceeds levels associated with fever and hyperthermia (approximately 39.5 degrees C) field studies may provide an opportunity to determine the effects of severe heat stress on immunity. Field studies may also provide insight into the possible involvement of immune modulation in the aetiology of exertional heat stroke (core temperature > 40.6 degrees C) and identify the effects of acclimatisation on neuroendocrine and immune responses to exercise-heat stress. Laboratory studies can provide useful information by, for example, applying the thermal clamp model to examine the involvement of the rise in core temperature in the functional immune modifications associated with prolonged exercise. Studies investigating the effects of cold, high altitude and microgravity on immunity and infection incidence are often hindered by extraneous stressors (e.g. isolation). Nevertheless, the available evidence does not support the popular belief that short- or long-term cold exposure, with or without exercise, suppresses immunity and increases infection incidence. In fact, controlled laboratory studies indicate immuno-stimulatory effects of cold exposure. Although some evidence shows that ascent to high altitude increases infection incidence, clear conclusions are difficult to make because of some overlap with the symptoms of acute mountain sickness. Studies have reported suppressed cell-mediated immunity in mountaineers at high altitude and in astronauts after re-entering the normal gravity environment; however, the impact of this finding on resistance to infection remains unclear.

Increased megakaryopoiesis in cultures of CD34-enriched cord blood cells maintained at 39 degrees C

Based on previous evidence suggesting positive effects of fever on in vivo hematopoiesis, we tested the effect of hyperthermia on megakaryopoiesis (MK) in ex vivo cultures of CD34-enriched cord blood (CB) cells. The cells were cultured at 37 degrees C or 39 degrees C for 14 days in cytokine conditions optimized for megakaryocyte development and analyzed periodically. Compared to 37 degrees C, the cultures maintained at 39 degrees C produced significantly more (up to 10-fold) total cells, myeloid and MK progenitors, and total MKs, and showed accelerated and enhanced MK maturation with increased yields of proplatelets and platelets. This observation could facilitate clinical applications requiring ex vivo expansion of hematopoietic cells.

Whole-body hyperthermia (41.8 degrees C) combined with bimonthly oxaliplatin, high-dose leucovorin and 5-fluorouracil 48-hour continuous infusion in pretreated metastatic colorectal cancer: a phase II study

BACKGROUND

Second- and third-line treatments remain a challenge in advanced colorectal cancer. Studies of bimonthly regimens of high-dose leucovorin (LV) and 5-fluorouracil (5-FU) by continuous infusion combined with oxaliplatin (L-OHP) have shown encouraging response rates in patients not responding to a bimonthly LV/5-FU regimen. Hyperthermic enhancement of L-OHP efficiency by increased DNA adduct formation has been demonstrated in vitro. This study was designed to address feasibility, toxicity and efficacy issues of whole-body hyperthermia (WBH) as an adjunct to L-OHP/LV/5-FU in pretreated patients after progression to first- and second-line treatments with LV/5-FU by continuous infusion and irinotecan.

PATIENTS AND METHODS

Forty-four patients with advanced colorectal cancer, who had progressed during or within 3 months after completion of chemotherapy with LV/5-FU 24-h infusion (LV/5-FU(24h)) (eight patients) or irinotecan combined with or after LV/5-FU(24h )(36 patients), were treated with L-OHP 85 mg/m(2), 2-h intravenous (i.v.) infusion, followed by LV 200 mg/m(2), 1-h i.v. infusion, and 5-FU 3 g/m(2), 48-h continuous infusion. Every second cycle of the biweekly regimen was combined with WBH, thus allowing a comparison of toxicity with and without WBH in the same patient. Whole-body hyperthermia was administered by a humidified radiant heat device. The target temperature of 41.8 degrees C was maintained for 60 min. L-OHP (2-h infusion) was started at a core body temperature of 39 degrees C.

RESULTS

All patients could be evaluated for toxicity, and 41 patients were evaluable for response. A total of 273 L-OHP-containing regimens were administered, 130 with and 143 without WBH. Hyperthermic treatment combined with L-OHP/LV/5-FU showed no unexpected toxicities. WHO grade 3 toxicities were rare and evenly balanced between cycles given with or without WBH. One early death occurred due to sepsis and tumor lysis. The overall response rate was 20%, with two complete and six partial responses. Twenty-three patients (56%) had stable disease and nine patients (22%) progressive disease. With a median observation time of 70 weeks, the median time to progression was 21 weeks [95% confidence interval (CI) 17-25 weeks] and the median survival was 50 weeks (95% CI 39-61 weeks) from the start of therapy.

CONCLUSIONS

This trial suggests some advantage of combining L-OHP/LV/5-FU with WBH. Results compare favorably with the activity of similar regimens without WBH in less extensively pretreated patients. These data support further evaluation and warrant phase III studies.

Perfusion induced hyperthermia for oncologic therapy with cardiac and cerebral protection

Cancer can be preferentially damaged and killed at temperatures above 41.0 degrees C. However, the heart and brain malfunction at this temperature, limiting the application of systemic hyperthermia in the treatment of metastatic cancer. We created a hyperthermic perfusion system that maximizes the temperature differential produced and extends the safe hyperthermic time. Mongrel dogs were anesthetized and mechanically ventilated. Temperature probes were placed in the rectum, bladder, peritoneal cavity, proximal aorta, pulmonary artery, and right tympanic canal. Venoarterial perfusion was instituted and the perfusate was warmed to 44 to 45 degrees C. The dogs' rectal temperature was elevated to > or = 42 degrees C for 4 hours. A small amount of venous blood was cooled to 28 to 30 degrees C and reperfused into the right atrium to maintain the pulmonary artery temperature < or = 38 degrees C. At the end of the perfusion, the dogs were decannulated, recovered, and returned to their cages for observation. Ten of 11 dogs survived the operative procedure, and no neurologic deficits were observed. The rectal temperature was successfully elevated to > or = 42 degrees C for 4 hours while maintaining the heart and brain at < or = 38 degrees C. Moderate serum biochemical changes were observed postprocedure. However, only the aspartate transaminase and alkaline phosphatase levels remained elevated above both the baseline and canine reference values by day 7. Lower abdominal and pelvic hyperthermia at 42 degrees C can be safely produced and maintained for 4 hours using an extracorporeal perfusion circuit, while protecting the heart and brain from temperature elevation.

Monitoring arterial blood pressure during whole body hyperthermia

BACKGROUND

For monitoring of arterial blood pressure (ABP) during whole body hyperthermia (WBH) different methods have been recommended. This investigation was performed to evaluate the agreement of invasive measurements at various sites, and to compare invasive and non-invasive methods of ABP monitoring under conditions of a heat-induced extreme vasodilation.

METHODS

In 19 patients, 48 treatments with WBH were performed. Measurements of ABP in the radial and femoral artery by oscillometry and by sphygmomanometry were taken at four temperature levels during WBH (37, 40, 41.8 and 39 degrees C).

RESULTS

Significant differences were observed between invasive and non-invasive methods for systolic ABP, with higher values for non-invasive measurements. When compared with both invasive measurements for diastolic blood pressures, sphygmomanometry gave higher values and oscillometry gave lower values. Sphygmomanometry also showed higher values for mean ABP compared with all other techniques, while measurements in radial and femoral artery and by oscillometry only differed by approximately 5 mmHg.

CONCLUSION

The mean arterial pressure and not the systolic and/or diastolic pressure should guide hemodynamic management during WBH. The sphygmomanometric technique is not recommended for use during hyperthermia.

Melphalan resistance and photoaffinity labelling of P-glycoprotein in multidrug-resistant Chinese hamster ovary cells: reversal of resistance by cyclosporin A and hyperthermia

The multidrug resistance phenotype is often associated with overexpression of P-glycoprotein, an energy-dependent efflux pump responsible for decreased intracellular accumulation of chemotherapeutic agents. The role of P-glycoprotein in the mechanism of cross-resistance to melphalan in multidrug-resistant Chinese hamster ovary cells (CH(R)C5) was investigated by photoaffinity labelling of P-glycoprotein using [3H]azidopine. We investigated whether the chemosensitiser cyclosporin A and hyperthermia, either used alone or combined, could reverse melphalan resistance and alter transport processes for [14C]melphalan in CH(R)C5 cells. Melphalan inhibited azidopine photolabelling of P-glycoprotein, implicating drug efflux mediated by P-glycoprotein in the mechanism of melphalan resistance in CH(R)C5 cells. Azidopine photolabelling also was inhibited by the chemosensitiser cyclosporin A, which binds to P-glycoprotein. Cyclosporin A alone reversed melphalan resistance in CH(R)C5 cells, but had no effect in drug-sensitive AuxB1 cells. Hyperthermia (40-45 degrees) alone increased melphalan cytotoxicity in both cell lines. When hyperthermia was combined with cyclosporin A, a large increase in melphalan cytotoxicity occurred, but only in CH(R)C5 cells. This effect increased with temperature and exposure time. Sensitisation to melphalan cytotoxicity by heat and cyclosporin A in CH(R)C5 cells appeared to be explained by altered drug transport processes. Lower accumulation of melphalan occurred in CH(R)C5 cells than in drug-sensitive cells. At 37 degrees, cyclosporin A increased drug accumulation in CH(R)C5 cells, but not in AuxB1 cells, by slowing drug efflux from cells. Heat alone increased both melphalan uptake and drug efflux for both cell lines. Our findings suggest that the combination of cyclosporin A and hyperthermia could be very useful in overcoming melphalan resistance by increasing intracellular drug accumulation in multidrug-resistant cells.

Hyperthermic modulation of SN-38-induced topoisomerase I DNA cross-linking and SN-38 cytotoxicity through altered topoisomerase I activity

The effect of different temperatures (37-42.5 degrees C) on SN-38 (the active metabolite of CPT-11) cytotoxicity was examined in the human lung carcinoma cell lines H460 and Calu-6 as well as the murine fibrosarcoma cell line L929. The cytotoxicity of SN-38, determined by MTT cell survival assay, was significantly increased in each cell line in combination with 41.8 degrees C hyperthermia (x60-120 min); the combination of SN-38 with 40.5 degrees C and 42.5 degrees C, however, was unchanged compared to 37 degrees C. Determination of topoisomerase (Topo) I DNA cross-linking in Calu-6 cells and L929 cells after treatment with SN-38 showed the same temperature profile as seen in the cell-survival assays with increased Topo I DNA cross-linking after treatment with the combination of SN-38 and 41.8 degrees C hyperthermia and unchanged Topo I DNA cross-linking at 40.5 degrees C and 42.5 degrees C. To test the hypothesis that increased Topo I DNA cross-linking and SN-38 cytotoxicity at 41.8 degrees C is caused by hyperthermia-modulated changes in Topo I activity, catalytic activity of Topo I extracted from each cell line and of purified human Topo I was determined at 20-42.5 degrees C. Topo I activity was found to be gradually increased with rising temperatures, resulting in significantly higher activity at 41.8 degrees C compared to 37 degrees C; further increase of temperature past 41.8 degrees C decreased Topo I activity back to levels found at 37 degrees C. Our data are used to explain a series of events resulting in hyperthermic enhancement of Topo I DNA cross-linking and SN-38 cytotoxicity in combination with 41.8 degrees C hyperthermia via increased Topo I activity.

Heat exposure and drugs. A review of the effects of hyperthermia on pharmacokinetics

Acute heat loading is encountered in several everyday situations, during physical exercise or work in a hot climate are just 2 examples. Special forms of heat exposure include different types of steam baths and saunas. External heating induces changes in haemodynamics, body fluid volume and blood flow distribution, which in turn may affect the pharmacokinetics of a drug and the therapeutic response. Documentation of the effects of heat exposure on the pharmacokinetics of drugs in humans is very limited, but based on the documentation some general conclusions can be drawn. The effects of external heating on absorption and elimination of those orally administered drugs which have been studied (e.g. midazolam, ephedrine, propranolol and tetracycline), have been minor. Systemic absorption of transdermally and subcutaneously administered drugs [insulin, nitroglycerin (glyceryl trinitrate) and nicotine] is in most cases enhanced by external heating, leading to higher plasma drug concentrations. In general, pharmacokinetic interactions between heat exposure and drug therapy are rare and limited to special situations, in which local blood flow (for example, over the skin) is enhanced many-fold because of hyperthermia. When pharmacodynamics are concerned, in most cases the probability of interactions is low, but in the treatment of malignant tumours hyperthermia may potentiate cytotoxic effects of drugs without enhancement of myelosuppressive effects.

Dynamic changes in serum erythropoietin levels in solid tumour patients undergoing 41.8 degrees C whole body hyperthermia and/or chemotherapy

Whole Body Hyperthermia (WBH) has been shown to have physiological effects on myeloid and megakaryocytic haematopoietic tissue via both cytokine induction, as well as hormonal changes. In order to extend this knowledge base to the erythroid cells, endogenous erythropoietin (EPO) levels were studied in 17 cancer patients receiving 41.8 degrees C WBH and/or chemotherapy, as well as in 53 anaemic and non-anaemic control patients. Pre-treatment EPO levels showed a 'blunted' EPO response in cancer patients compared to the control patients. Post-treatment data demonstrated a significant chemotherapy induced increase in EPO levels with a peak at 36 to 48 hours (independent of changes in haemoglobin) and 10 to 13 days post chemotherapy (simultaneously with a drop in haemoglobin levels). The early change in EPO levels was not influenced by the addition of 41.8 degrees C (x 60 min) WBH to the same chemotherapy regimen, i.e., ifosfamide, carboplatin, and etoposide. Taken collectively, our data show that endogenous EPO levels in cancer patients can be effected by chemotherapy (independent of changes in haemoglobin). This EPO response to chemotherapy is not impacted on by 41.8 degrees C WBH. A relevant secondary conclusion can also be derived from this investigation, i.e., caution should be exercised as to the use of EPO levels during chemotherapy as predictors of exogenous EPO efficacy.

Influence of circadian rhythm on 41.8 degrees C whole body hyperthermia induction of haematopoietic growth factors

It has previously been reported by the authors that the induction of a series of cytokines by 41.8 degrees C Whole Body Hyperthermia (WBH), i.e., interleukin (IL)-1 beta, IL-6, IL-8, IL-10, tumour necrosis factor alpha, and granulocyte colony stimulating factor (G-CSF). As cytokine levels are known to fluctuate as a function of time, i.e. circadian rhythm, the influence of circadian time structure on specific haemotopoetic growth factors is studied, i.e. granulocyte macrophage colony stimulating factor (GM-CSF), G-CSF and IL-3. Samples derived from four cancer patients undergoing extracorporeal WBH resulted in the following observations: G-CSF is induced by WBH, but unaffected by circadian rhythm, IL-3 fluctuates with circadian rhythm, but is unaffected by WBH. Specifically, a biphasic temporal pattern of IL-3 (i.e. with a peak at 2:00 and 5:00 a.m. and a nadir concentration at 5:00 p.m.) was found by analysis of variance. GM-CSF was below the lower detection limit pre and post WBH. The data show the importance of measuring cytokines as a function of time to circumvent conflicting results in the inter-relationship of 'true' cytokine induction and circadian rhythm. The implications of the differential induction of G-CSF, GM-CSF, and IL-3 for myeloprotection after WBH are discussed.

Lack of thermal enhancement for taxanes in vitro

The taxanes represent a new class of clinical chemotherapeutic agents. A series of in vitro studies were independently of each other initiated in two different institutes (Amsterdam and Madison) to test the hypothesis that hyperthermia might enhance the cytotoxicity of taxanes. Clonogenic capacity experiments (Amsterdam) included the exposure of R1- and SW 1573-cells to 1, 4, or 24 h of paclitaxel with heat 43 degrees C x 60 min in the last hour of drug treatment or at 24, 48 as well as 72 h post drug treatment. Survival assay experiments (Madison) included the exposure of L-929-cells to paclitaxel and docetaxel for 24 h with heat 41.8 degrees C x 60 min the first or last hour of drug treatment as well as 24 and 48 h post treatment. No thermal enhancement of cytotoxicity for the taxanes was observed in these human and murine cell lines, with congruent data in both institutes. In addition, high performance liquid chromatography studies at 41.8 degrees C and 43 degrees C demonstrated paclitaxel and docetaxel were heat stable.