Presently, there are no effective treatments for chronic human immunodeficiency virus (HIV) infection. Moreover, there are no effective treatments for Kaposi's sarcoma (KS), the most common HIV-associated malignancy. Whole-body hyperthermia (WBHT) has been used extensively both as an adjunctive treatment and as salvage therapy for a number of malignancies (1-4). Although WBHT can result in marked physiological and biochemical changes, morbidity and mortality have been surprisingly low, even in debilitated elderly cancer patients (5,6). The value of WBHT as a potential therapeutic modality for chronic HIV infection was first proposed by one of us 8 years ago (7,8) and subsequently by another investigator (9). The rationale underlying this contention is that HIV is heat-sensitive (10-12) and that HIV-infected lymphocytes are more heat-sensitive than uninfected cells (13). It is now appreciated that cell free virus is found in peripheral blood during HIV infection and that the interstitial spaces of lymphoid follicles are important reservoirs of virus at all stages of HIV infection. This continues until involution of follicular centers at advanced stages of HIV disease occurs (14,15). The numbers of both acutely and chronically infected cells in lymphoid tissue have been shown to be fivefold to 10-fold higher than in peripheral blood (14). Analysis of sequential tonsillar biopsies, plasma, and peripheral blood mononuclear cells indicates that lymphoid tissue has HIV RNA levels 10-15 times greater than that in circulation (16). The higher concentration of infected cells and HIV RNA is undoubtedly multifactorial. We believe that WBHT, which alters lymph flow, cellular trafficking, and compartmentalization in lymphoid tissue in both sheep (17) and humans (18), could play a role in modifying the course of HIV infection.
The first AIDS patients were treated in Atlanta in 1990 by Drs. Alonso and Logan (19,20). Subsequently, the National Institutes of Health of the United States Public Health Service created a review panel to evaluate the use of WBHT as a potential treatment modality for people with chronic HIV infection. On the basis of their review the panel stated that... “there appears to be no clinical, immunological, or virological support for the use of hyperthermia in the treatment of HIV disease or Kaposi's sarcoma...” (21). It has been, and continues to be, our contention that the review panel's report was, at best, premature (22,23) and that, as a consequence, that report has prevented any legitimate inquiry into, or evaluation of, WBHT in the treatment of HIV infection.
Recently, the United States Food and Drug Administration (FDA) approved a feasibility trial to test the safety and effects of WBHT on six patients with AIDS. That study was conducted in July of 1994. The results of that trial, using WBHT equipment designed to minimize the physiological and biochemical perturbations that occur during WBHT, are described below.
METHODS
Study Subjects
Six male homosexuals, CDC class C-3, met entry criteria including normal cardiac and pulmonary function, Karnofsky Performance Score (KPS) ≥70%, and absence of acute infections (Table 1). All subjects underwent screening and follow-up clinical evaluations by the principal investigator (PI: C.R.S.). Assessment of KS lesions was performed by a board-certified dermatologist at the same time as the evaluation by the PI. Three of the subjects were patients of the PI; the other three were referred from other local physicians. Informed consent was obtained from each patient prior to participation in the study.
Study Protocol
The feasibility study was approved by the FDA and the Institutional Review Board of St. Elizabeth's Hospital. Laboratory and clinical evaluations were performed within 2 weeks of treatment and every 2 weeks thereafter for 8 weeks. Clinical evaluations included complete history and physical examination as well as assessment of KPS and a quality of life questionnaire. Laboratory measurements included chemical profiles, electrolytes, liver function tests, and complete blood count. Immunological and virological evaluations included measurement of beta-2-microglobulin (β2-m), lymphocyte phenotype, immune complex dissociated (ICD) p24 antigen, HIV DNA by polymerase chain reaction (PCR) (Roche Biomedical Laboratories, Research Triangle Park, NC, U.S.A.), and plasma HIV RNA by branched-chain (bDNA) analysis (Quantiplex HIV-RNA Assay Kit, Chiron, Emeryville, CA, U.S.A.). In addition, each patient was throughly examined by the coinvestigator (S.R.A.) prior to and during the 24 h following WBHT.
The six patients were randomized into two groups (groups 1 and 2) to receive WBHT at either 40°C or 42°C, respectively, for 1 h. The 40°C temperature was chosen as a control because, in the opinion of the investigators, one treatment at that temperature would not be expected to have any antiretroviral and/or antineoplastic effect. All subjects were blinded as to which temperature they had received. An extracorporeal WBHT system was used for the treatment.
Briefly, the Biologic-HT system can create elevated core body temperatures while automatically controlling blood chemistries. The Biologic-HT system uses a roller pump to pull blood from an arterial access at 600-800 ml/min, passes it through a metal-surfaced heat exchanger, and returns it through a venous access (Fig. 1). Some of the blood passes through a modified Biologic-DT sorbent-based dialysis device (Biologic-HT) that has been described previously (24-26). The HT system is connected in parallel with the blood tubing between the roller pump and heat exchanger as depicted in Fig. 1. By simple algorithms, the Biologic-HT alters blood in- and out-flow times to adjust the ultrafiltration rate, automatically reinfuses fluid to maintain adequate fluid balance, and controls dialysate and blood chemistries.
The treatment protocol involved the placement of femoral arterial and venous catheters and a Swan-Ganz catheter introduced into an internal jugular vein. Other catheters and electrodes included peripheral arterial and venous lines, Foley catheter (with temperature probe), esophageal and rectal temperature probes, bioimpedance and echocardiographic (ECG) electrodes, and a nasal oxygen cannula. Anesthesia was maintained as needed with thiopental sodium and the patient was heparinized. A Bair-Hugger heated-air blanket was placed over the patient to minimize heat loss. A Cincinnati Sub-Zero (CSZ) hyper-hypothermia machine was modified to provide water at 48°C to the heat exchanger until the subject's core body temperature reached either 40°C or 42°C. CSZ water temperature was then adjusted to maintain the prescribed core temperature for 1 h. A Bo-Med bioimpedance monitor measured end-diastolic and cardiac indices. Fluid replacement was administered to maintain a normal end-diastolic index. After 1 h at hyperthermia, the CSZ temperature was set at 30°C until the core temperature fell to 38°C. All temperature probes and all catheters, except the Foley and the peripheral venous line, were then removed and the patient was transferred to a general ward room and allowed to awaken under observation.
One patient was intubated before the treatment by design. This patient had pulmonary KS and a history of recent hemoptysis. Intubation was performed to observe signs of pulmonary bleeding and/or respiratory distress during the treatment.
Statistical Analysis
Mean and standard errors were determined for all measurements. Results were determined to be statistically significant if the p value was ≤0.05 by t test or analysis of variance (ANOVA) according to standard analysis.
RESULTS
Patient Characteristics
Table 2 shows the immunological and virological characteristics of the study subjects upon entry to the study. The two groups were similar in all clinical and laboratory features. All patients had prior HIV-related complications and mild, chronic fevers, not uncommon for patients with advanced HIV disease. One patient in each group also had visceral KS (40°C group, gastric; 42°C group, pulmonary).
Clinical Responses following WBHT
Subjectively, as assessed by the quality of life questionnaires, subjects treated at 40°C did not feel any difference after WBHT. In addition, their body weights did not change during the 8-week follow-up period. Two of the 42°C subjects felt better after the treatment and had gained weight during the follow-up period. One of these had, however, electively started chemotherapy at week 6 of follow-up.
One of the subjects in the 40°C group developed a severe encephalopathy at 6 weeks postprocedure and expired 3 weeks later. He had been working continuously until he became ill. Although there is no way to be entirely certain, the fact that this occurred more than 1 month after the procedure and the fact that he was treated at 40°C and not 42°C rules against his death being attributed to the treatment.
Physiological Changes during WBHT
Figure 2 depicts temperature curves of one representative subject in each group. As can be seen from the graphs, the desired temperatures were maintained for 1 h. Moreover, rectal, esophageal, and bladder temperatures correlated very closely. The warming phase required 60-100 min for the 40°C group and 120-170 min for 42°C WBHT. Figure 3 shows the hemodynamic responses during the protocol in representative subjects of each group. WBHT at 42°C was physiologically more rigorous. Cardiac index (CI) assessed by bioimpedance increased modestly in 40°C subjects; CI rose 100% or more above baseline in the group treated at 42°C. CI determinations by thermodilution showed the same trends. Mean arterial blood pressure decreased modestly in patients undergoing WBHT at 40°C and decreased markedly at 42°C. End-diastolic index decreased during the warming phase in both groups; during hyperthermia it increased in response to fluid challenge more predictably than did pulmonary capillary wedge pressure.
Biochemical and Hematological Changes during and after WBHT
Blood chemistries were measured immediately before and after each treatment and every 2 weeks during the 8-week follow-up as described above. Figure 4 shows the pre-WBHT and immediate posttreatment measurements of the two groups. The 40°C subjects did not have any significant changes in any blood chemistries during or after treatment. Subjects treated at 42°C had modest increases in creatine phosphokinase (CPK), serum glutamic-oxaloacetic transaminase (SGOT), serum glutamic-pyruvic transaminase (SGPT), and total bilirubin immediately posttreatment. Serum phosphate levels fell slightly at the end of hyperthermia in this group as seen in the figure. In addition, the platelet count fell and bicarbonate (CO2), prothrombin time, and free hemoglobin increased in the group treated at 42°C (Fig. 5). By 2 weeks post-WBHT, all chemistries had returned to normal except for minimal changes in one 40°C patient and two 42°C patients. None of these changes was associated with clinical symptoms and all normalized by the end of the follow-up period.
Effect of WBHT on KS
All 40°C and 42°C subjects experienced some improvement in KS lesions during the first week following treatment. This was evidenced by a lightening of color and a decrease in size of cutaneous lesions. In addition, the subject with severe palatal KS and the one with gastric involvement reported significant symptomatic improvement during the first week. However, in all but one patient, the KS lesions regressed to pretreatment status by 2 weeks post-WBHT. The one exception was a subject treated at 42°C in whom the size of the KS lesions continued to diminish during the follow-up period. In two subjects (one 40°C, one 42°C), progression of KS occurred, necessitating chemotherapy at 6 weeks posttreatment.
Effect of WBHT on Immunological and Virological Parameters
Following WBHT at 40°C, CD4 counts decreased and remained below pretreatment values throughout follow-up (Fig. 6a). There was no change, however, in CD4 counts following hyperthermia at 42°C (Fig. 6b). β2-m remained unchanged in all subjects following WBHT, as seen in Table 3.
Virological results are also shown in Table 3 as well as in Fig. 7. Following WBHT at 40°C, there were no changes in plasma HIV RNA either immediately after treatment or during the 8-week follow-up period (Fig. 7a). Plasma HIV RNA did decrease, however, immediately following 42°C WBHT but returned to pretreatment levels at 1 week post-WBHT (Fig. 7b). HIV DNA, as assessed by qualitative PCR, was positive in all subjects and remained detectable in all subjects during follow-up. p24 antigen did not change significantly in either the 40°C or 42°C group, as seen in Table 3.
Side Effects and Complications of WBHT
All six WBHT treatments were performed without difficulty or unexpected consequences exactly according to the protocol. There were no untoward side effects following the treatment except mild muscle soreness, tenderness over the vascular access sites, and some fleeting fatigue. The one subject who was electively intubated developed transient eustachian tube blockage and worsening of chronic sinusitis for the first 24 h posttreatment. Two of three subjects treated at 42°C developed heel blisters post-WBHT and one subject developed skin imprints from the heating pad that persisted for approximately 2 weeks posttreatment. As described above, there was one death in the 40°C group 8 weeks following the procedure.
DISCUSSION
Although the present study included only a limited number of subjects, as mandated by the FDA, it does suggest that the Biologic-HT system can perform WBHT safely in subjects with advanced HIV disease. This confirms the general safety of WBHT shown in a number of previous studies in patients with various malignancies (6,27). However, the use of WBHT in HIV-positive individuals, either with or without malignancies, has been reported by only one investigator (19,20,28), and significant problems were associated with his work (21). The present study is the first FDA-approved trial of hyperthermia as a potential therapeutic modality in patients with AIDS.
Our work suggests that the clinical side effects of WBHT are greater at 42°C than at 40°C but still minimal and relatively short-lived. We believe that treatment at high core temperatures is safe when properly monitored and when a simple algorithm for fluid replacement is followed. Briefly, this is accomplished by measuring the end-diastolic volume of the heart via bioimpedance and administering fluid to maintain a mid-normal level. Although mean arterial blood pressure fell during WBHT (especially at 42°C), it returned to normal during cooling. There were no signs of excess pulmonary fluid or edema in spite of 4-5 1 of fluid administered during the treatment. Bioimpedance does appear to be more consistent in cardiovascular monitoring during WBHT than do Swan-Ganz measurements, and an end-diastolic pressure is a better end-point for fluid infusion than an increased pulmonary capillary wedge pressure. Some clinical side effects can easily be eliminated in future studies: placing a foam mattress between the water blanket and the patient should eliminate skin lesions during 42°C WBHT; avoiding intubation may eliminate any sinus or eustachian tube problems (easily done if patients with pulmonary KS are excluded).
There were few significant biochemical changes at either 40°C or 42°C. Elevation of liver enzymes occurred at 42°C, but changes were modest and returned to pretreatment levels by 2 weeks post-WBHT. Mild asymptomatic myonecrosis is probably unavoidable at 42°C. These results confirm previous reports in other patient populations (4-6). WBHT at 40°C does not cause any hemolysis even in patients with chemical signs of hemolysis before treatment; WBHT at 42°C increases free hemoglobin slightly in patients whose levels are already elevated (Fig. 5).
The effects of WBHT on KS suggested a positive, albeit transient, effect. This confirms the results of local hyperthermia on KS by several investigators using various techniques (29-31). The results of the present study do not appear to agree with the work of Alonso et al. (28) in which complete or partial regressions were seen at 30 days posttreatment in 20 of 29 subjects with persistent remissions at 120 days. The discordant results may be explained, however, when CD4 counts are taken into consideration. In the study by Alonso et al. (28), only four of 13 subjects whose CD4 count was less than 50/mm3 responded; of 18 subjects whose pretreatment CD4 count was greater than or equal to 50, 16 responded.
Although our feasibility study had only a limited number of subjects, we are encouraged by some of the immunological and virological results. As shown in Fig. 6, CD4 counts decreased following WBHT at 40°C (the control group) while remaining unchanged following hyperthermia at 42°C. Viral load as assessed by measuring plasma HIV RNA did not change following hyperthermia at 40°C, as shown in Fig. 7a. However, there was a statistically significant reduction in HIV RNA immediately after cool-down in the 42°C group before returning to pretreatment levels at 1 week post-WBHT (Fig. 7b). However, this decrease, although statistically significant, may not be clinically or virologically meaningful. At the present time, changes in plasma HIV RNA by bDNA analysis are virologically significant only if a threefold change occurs (32,33). This did not happen in this study. Nevertheless, the difference in responses between the two groups is encouraging and consistent with in vitro studies demonstrating that HIV is heat-sensitive, being 40% inactivated at 42°C for 30 min and 100% inactivated at 56°C (10-12). Indeed, HIV-infected lymphocytes are more heat-sensitive than uninfected cells when maintained at 42°C for up to 10 h (13) and virally infected NIH/3T3 cells are more thermosensitive than uninfected cells (34,35).
A major argument against the use of WBHT for the treatment of HIV infection has been the report that heat may upregulate HIV production (36). Although only a limited study, the viral load results suggest that upregulation probably did not occur in this trial. Regardless, the assumption that upregulation is detrimental may not be valid. Indeed, although only speculative at the present time, upregulation may actually be beneficial, and it contributes significantly to our rationale as to why WBHT may be therapeutically useful. For example, immune recognition and the elimination of upregulated cells is likely to be enhanced as a result of the appearance of antigenic proteins on the surface of formerly quiescent cells (37-39). Moreover, productively infected cells have markedly compromised plasma membranes (40-42), which would tend to increase their thermosensitivity (34). The observation that thermosensitivity of NIH/3T3 cells infected with Moloney murine leukemia virus is positively correlated with virus production supports the above contention. Such cells, when upregulated by a priming heat dose, were more thermosensitive to a second heat exposure after incubation at 37°C (35; M. A. Shenoy and M. B. Yatvin, unpublished data).
In December 1994, based on the results of the trial described herein, the FDA granted permission for a second clinical trial. The scope of the second trial has been expanded to include two treatment groups and one control group (total of 30 subjects). WBHT will be administered twice allowing a 5-day interval between treatments in less immunocompromised subjects. As suggested above, there are a number of reasons to believe that a properly timed second WBHT treatment would be beneficial. The second treatment may inactivate free virus resulting from upregulation and would, therefore, be expected to kill infected cells surviving the initial treatment.
Acknowledgment: This project was supported in its entirety by IDT, Inc.
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FIG. 1:
. Major components of the Biologic-HT (hyperthermia) system with hook-up to a subject is schematically shown. Modifications of the Biologic extracorporeal detoxifier system
(4,5) are described in the text.
. Temperature curves obtained in one representative subject in each group. a: Subject 3 underwent WBHT at 40°C. b: Subject 5 underwent WBHT at 42°C.
FIG. 3:
. Hemodynamic parameters obtained in one representative subject in each group. a: Subject 3 underwent WBHT at 40°C. b: Subject 5 underwent WBHT at 42°C. BoMed, bioimpedance; Cl, cardiac index; CO, cardiac output; MAP, mean arterial pressure; EDl, end-diastolic index; PCWP, pulmonary capillary wedge pressure.
FIG. 4:
. Biochemical parameters obtained immediately prior to and after hyperthermia.
FIG. 5:
. Hematological parameters obtained immediately prior to and after hyperthermia.
FIG. 6:
. Absolute CD4 counts expressed as a percent of the pre-WBHT values. a: Results of subjects undergoing 40°C WBHT. b: Results of subjects undergoing 42°C WBHT. *Results are significantly lower than the pre-WBHT values: p < 0.02.
FIG. 7:
. Plasma HIV RNA expressed as a percent of the pre-WBHT values. a: Results of subjects undergoing 40°C WBHT. b: Results of subjects undergoing 42°C WBHT. **Result is significantly less than the pre-WBHT and follow-up values: p < 0.05. Note the differences in scales between the two graphs.
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