Drug-induced tolerance to allografts in mice. IV. Mechanisms and kinetics of cyclophosphamide-induced tolerance

Mechanisms and kinetics of tolerance in AKR mice induced using i.v. priming with viable C57BL/6 spleen cells and treatment with cyclophosphamide 2 days later were analyzed. In this tolerance induction system, some lymphocyte populations mediating delayed foot-pad reaction and cytotoxic activity were resistant to tolerance induction and remained in a sensitized state after cyclophosphamide treatment. These populations were considered to be qualitatively distinct from populations sensitive to cyclophosphamide, because delayed foot-pad reaction and cytotoxic lymphocyte activity were stronger in tolerant mice than in control mice in the early stages of tolerance induction, but were not augmented after immunization with C57BL/6 spleen cells, C57BL/6 skin grafts, or EL4 tumor grafts in the absence of suppressor T cells. One of the important differences in these two lymphocyte populations may be the capacity for clonal expansion.     

Ability of low-dose cyclophosphamide to overcome metastasis-induced immunosuppression

Background: Lymphocytes obtained from tumor-draining lymph nodes (DLN) can have potent in vivo antitumor activity after in vitro activation with bryostatin 1 and ionomycin. However, the presence of visceral metastases in the donor can inhibit the effectiveness of such lymphocytes. In the present study, we tested the ability of low-dose cyclophosphamide to overcome metastasis-induced immunosuppression in a murine model. Methods: Mice were injected with MCA-105 sarcoma cells in the footpad alone or in the footpad and the tail vein to establish lung metastases. Cyclophosphamide was given i.p. 1 day before harvesting the draining popliteal lymph nodes. For all donor groups, DLN cells were activated with 5 nM bryostatin 1 and 1 µM ionomycin and cultured for 7 days in 20 U/ml IL-2. Activated DLN cells were then adoptively transferred to syngeneic mice with 3-day lung metastases. Results: The adoptive transfer of DLN cells from mice with footpad tumors only significantly reduced the number of lung metastases compared to untreated mice. However, activated DLN cells obtained from mice with both footpad and lung tumors were significantly less effective. Treatment of similar donor mice with 10 mg/kg cyclophosphamide significantly improved the antitumor activity of adoptively transferred cells. This dose of cyclophosphamide did not reduce the number of cells obtained from each lymph node or the expansion of cell numbers in vitro. Conclusions: These results suggest that the administration of low-dose cyclophosphamide prior to harvesting DLN cells may improve the success of adoptive immunotherapy in cancer patients.This paper received the Residents' Poster Prize at the 46th Annual Cancer Symposium of the Society of Surgical Oncology, Los Angeles, March 18–21, 1993.     

Spermiogenic germ cell phase-specific DNA damage following cyclophosphamide exposure

The production of genetically competent spermatozoa is essential for normal embryo development. The chemotherapeutic drug cyclophosphamide creates cross-links and DNA strand breaks in many cell types, including germ cells. This study assessed the phase specificity of the susceptibility of spermiogenic germ cells to genetic damage induced by cyclophosphamide. Adult male rats were given cyclophosphamide using one of four schedules: 1) high dose/acute- day 1, 100 mg/kg; 2) low dose/subchronic, 4 days-days 1-4, 6.0 mg/kg/d; 3) high dose/subchronic, 4 days-day 1, 100 mg/kg, and days 2-4, 50 mg/kg/d; and 4) low dose/chronic-daily, 6.0 mg/kg/d for 14-28 days. To capture cauda epididymal spermatozoa exposed to cyclophosphamide during late, mid-, and early spermiogenesis, animals were sacrificed on days 14, 21, and 28, respectively. Spermatozoa were analyzed for DNA strand breaks using the comet assay. No dramatic increases in damage were seen after high-dose/acute exposure to cyclophosphamide. Subchronic exposure showed a dose-related increase in DNA damage; maximal damage, as demonstrated by comet tail parameters, was seen after 21 days, reflecting an increased susceptibility of step 9-14 spermatids. Low-dose chronic exposure to cyclophosphamide induced DNA damage, which reached a plateau by day 21. The magnitude of damage at all time points after low-dose chronic exposure was much greater than that following low-dose exposure for 4 days, indicating an accumulation of damage over time. Thus, the DNA damage induced by cyclophosphamide is germ cell phase-specific. The most damaging effects of cyclophosphamide occurred during a key point of sperm chromatin remodeling (histone hyperacetylation and transition protein deposition). We speculate that strand breaks disrupt chromatin remodeling, hence affecting chromatin structure and embryo development.     

Cyclophosphamide‐induced tolerance in kidney transplantation avoids long‐term immunosuppressive therapy

There has recently been remarkable progress in immunosuppressive agents, such as tacrolimus and cyclosporine. Therefore, the rate of organ establishment has improved in transplantation. However, immunosuppressive agents generally suppress the function of T cells. Thus, opportunistic infections, such as cytomegalovirus infection, are still a major problem in kidney transplantation. Induction of specific tolerance to avoid immunosuppressive drug therapy after kidney transplantation is considered as the ultimate goal of transplantation. Various factors induce tolerance that involves establishment of hematopoietic chimerism and various cell subsets. In particular, we have carried out various studies regarding the cyclophosphamide‐induced tolerance system. Tolerance is induced after establishment of hematopoietic chimerism after donor bone marrow transplantation. At the clinical stage, kidney transplantation before administration of cyclophosphamide after transfusion of bone marrow to create hematopoietic chimera is considered to be one of the most successful protocols. Furthermore, recent studies have shown the involvement of multiple populations of immune cells in preserving immunological tolerance and promoting long‐term renal grafts. The present review focuses on how cyclophosphamide and other immune factors induce tolerance in kidney transplantation.     

Immunotherapy with a tumor-infiltrating lymphocyte clone, soluble antigen, and cyclophosphamide.

A tumor-specific cytotoxic T-lymphocyte clone derived from bulk cultures of tumor-infiltrating lymphocytes attenuated the outgrowth of methylcholanthrene (MCA)-induced fibrosarcomas in C3H/HeJ mice. In 4-hour chromium 51-release assays, bulk cultures of tumor-infiltrating lymphocytes showed nonspecificity for MCA-induced tumors (MCA-F, MCA-D, MCA-SP), YAC-1, and EL-4. In contrast, a cytotoxic T-lymphocyte-cloned line specifically killed MCA-F, but not MCA-D or MCA-SP. Cytotoxic T-lymphocyte line 8 protected syngeneic hosts in local and systemic adoptive transfer assays. Hosts bearing 4-day-established MCA-F tumor cells received single agents or combinations of isoelectrophoretically purified butyl alcohol-extracted tumor-specific transplantation antigen (1 microgram/wk), cyclophosphamide (20 mg/kg on days 4 and 11), and/or cytotoxic T-lymphocytes (1 x 10(7) cells on days 7 and 14). While the mean tumor diameter was 11.6 +/- 1.3 mm in untreated hosts or after single treatments, the combination of tumor-specific transplantation antigen and cyclophosphamide along with the cytotoxic T-lymphocyte clone resulted in tumor diameters of 1.8 +/- 0.5 mm. The triple combination prolonged host survival from 39.6 +/- 1.6 to 57.2 +/- 4.7 days compared with antigen and cyclophosphamide treatment.     

Prevention of further cyclophosphamide induced hemorrhagic cystitis by hyperbaric oxygen and mesna in guinea pigs

PURPOSE: Hyperbaric oxygen therapy and mesna have been successfully used for hemorrhagic cystitis. We defined the protective effects of hyperbaric oxygen and mesna in further cyclophosphamide induced hemorrhagic cystitis in guinea pigs. MATERIALS AND METHODS: A total of 48 male guinea pigs were divided into 6 groups. All groups received 2 doses of 68.1 mg./kg. cyclophosphamide intraperitoneally at the same time intervals but group 1 served as controls. Group 2 received cyclophosphamide only, group 3 received hyperbaric oxygen treatment (2.8 ATA for 90 minutes twice daily) before and the day after further cyclophosphamide, group 4 received 21.5 mg./kg. mesna intraperitoneally only with further cyclophosphamide, group 5 received hyperbaric oxygen and mesna with further cyclophosphamide, and group 6 received hyperbaric oxygen before initial cyclophosphamide, between the 2 doses and after the further dose of cyclophosphamide, and mesna on the days of cyclophosphamide. RESULTS: Although mesna alone provided protection against cyclophosphamide induced cystitis in animal bladders, there was also significant damage compared with controls. When the uroprotective efficacy of mesna was supported with hyperbaric oxygen, bladder protection was promoted since mean histological scores and hematuria levels in this group did not differ from those in controls. CONCLUSIONS: According to this animal study using hyperbaric oxygen as adjuvant therapy in humans may be a better tool than mesna alone for the prophylaxis and treatment of cyclophosphamide induced hemorrhagic cystitis.     

Intravenous and portal venous administration of modified donor antigen prolongs rat parathyroid allograft survival

The effect of pretransplant (day -6) systemic intravenous or portal venous immunization with modified donor antigen combined with cyclophosphamide treatment (75 mg/kg on day -4) on rat parathyroid allograft survival was evaluated. Systemic intravenous preimmunization of Buffalo recipients with 10(8) untreated Lewis donor spleen cells plus cyclophosphamide resulted in 100% accelerated rejection of Lewis parathyroid allografts (mean survival time, 7.3 +/- 0.9 days vs 10.8 +/- 1.1 days for controls). Portal venous administration of untreated cells plus cyclophosphamide reduced accelerated rejection to 40% but could not prolong graft survival (10.8 +/- 2.7 days). Intravenous or portal venous preimmunization with heat-inactivated cells (45 degrees C for 60 minutes) plus cyclophosphamide also did not prolong graft survival, with accelerated rejection occurring in 20% and 40% of recipients, respectively. In contrast, preimmunization by either route with ultraviolet B-irradiated cells (UVB; 12,000 joule/m2) plus cyclophosphamide significantly prolonged graft survival (intravenous = 22.2 +/- 6.0 days and portal venous = 21.4 +/- 7.2 days; p less than 0.005), with no accelerated rejection. Preimmunization with UVB cells combined with cyclophosphamide was synergistic, because neither treatment alone prolonged allograft survival (UVB cell preimmunization only = 10.8 +/- 1.3 days; cyclophosphamide only = 12.6 +/- 2.6 days). The effect of UVB preimmunization was donor specific because third-party Wistar-Furth UVB cells had no effect on Lewis graft survival (12.5 +/- 2.9 days). We conclude that pretreatment with UVB-modified donor antigen plus cyclophosphamide induces allospecific immune hyporesponsiveness and prolongs parathyroid allograft survival.     

ANCA-associated vasculitides--advances in pathogenesis and treatment

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV) include Wegener granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome and renal-limited vasculitis. This Review highlights the progress that has been made in our understanding of AAV pathogenesis and discusses new developments in the treatment of these diseases. Evidence from clinical studies, and both in vitro and in vivo experiments, supports a pathogenic role for ANCAs in the development of AAV; evidence is stronger for myeloperoxidase-ANCAs than for proteinase-3-ANCAs. Neutrophils, complement and effector T cells are also involved in AAV pathogenesis. With respect to treatment of AAV, glucocorticoids, cyclophosphamide and other conventional therapies are commonly used to induce remission in generalized disease. Pulse intravenous cyclophosphamide is equivalent in efficacy to oral cyclophosphamide but seems to be associated with less adverse effects. Nevertheless, alternatives to cyclophosphamide therapy have been investigated, such as the use of methotrexate as a less-toxic alternative to cyclophosphamide to induce remission in non-organ-threatening or non-life-threatening AAV. Furthermore, rituximab is equally as effective as cyclophosphamide for induction of remission in AAV and might become the standard of therapy in the near future. Controlled trials in which specific immune effector cells and molecules are being therapeutically targeted have been initiated or are currently being planned.     

The effects of daily cyclophosphamide administration on the development and extent of primary experimental interstitial nephritis in rats

We examined the effects of daily cyclophosphamide administration on the development and extent of tubulointerstitial nephritis produced in rats injected with tubular basement membranes in adjuvant. 15 mg/kg/day of cyclophosphamide completely blocked the development of interstitial lesions, while 2 mg/kg/day enhanced the degree of interstitial injury. When cyclophosphamide in the higher dose was started early in disease, 12 days after immunization, protection from progression was also observed as well as significant reductive improvement. If cyclophosphamide was administered late in disease, 21 days after immunization, no further progression was demonstrable, but substantial injury remained. In the latter two experiments, the beneficial effects of cyclophosphamide could not be explained by a reduction in anti-tubular basement membrane antibodies bound to the kidney. In groups of immunized rats that were tested, however, cyclophosphamide was able to non-specifically impair the delayed-type hypersensitivity response to tubular antigen and PPD. We conclude, therefore, that cyclophosphamide, in high but not low dosage, if given before damage is extensive and prolonged, may successfully inhibit the cellular immune response producing primary interstitial nephritis.     

Improved therapeutic effect of sequential immunotherapy with cyclophosphamide, large doses of OK-432 and recombinant interleukin-2 in breast cancer patients with disseminated metastatic liver tumors

It has been generally agreed that the prognosis of widely spreaded "surgically unresectable" metastatic liver tumor originated from breast cancer is very poor. We reported here the result of clinical efficacy of sequential immunotherapy with intra-tumoral injection of large dose OK-432, after oral administration of cyclophosphamide during 7-10 days, and continuous perfusion of purified human recombinant interleukin-2 (rIL-2) from hepatic artery for the breast cancer patients with unresectable metastatic liver tumors. In all of 3 cases, metastatic liver tumor revealed overwhelming tumor reduction more than 50% of preoperative total tumor burden evaluated by computed tomography. Only 1 day after operation, large doses of OK-432 was injected intratumorally, both activity of Natural Killer (NK) cells and lymphokine activated killer (LAK) cells in peripheral blood lymphocytes were 5-20 folds augmented in all clinical trials. Serum tumor markers, i.e., Carcinoembryonic Antigen (CEA) and CA15-3, were rapidly decreased in all cases, respectively. Our clinical data indicate that intratumoral injection of large dose OK-432 and continuous administration of rIL-2 via hepatic artery, pretreated with cyclophosphamide, were clinically effective immunotherapy for reduction of metastatic liver tumor.     

Pulse cyclophosphamide inadequately suppresses reoccurrence of minimal change nephrotic syndrome in corticoid-dependent children.

BACKGROUND: In minimal change nephrotic syndrome (MNCS), the most common primary nephrotic syndrome in children, approximately 95% of cases show excellent responses to steroid therapy. However, responding patients may become steroid dependent and experience serious side effects. Although oral cyclophosphamide has been recommended in these patients, long-term side effects such as gonadal toxicity are an important concern. Therefore, cyclophosphamide pulses given intravenously may provide an option that maintains remission with less-frequent side effects. METHODS: We treated 20 primary steroid-dependent MCNS patients (15 boys and five girls) with intravenous cyclophosphamide. The patients were children with ages ranging from 3 to 15 years of age. Remission was induced by steroids followed by cyclophosphamide at a dose of 500 mg/m2 body surface area per month for 6 months. During this period, we attempted to completely withdraw steroids and maintain patients on cyclophosphamide alone. We monitored the patients for the occurrence of relapse and side effects during this period and for an additional 6 months after withdrawal of cyclophosphamide. RESULTS: At the end of the 6-month cyclophosphamide treatment period (i.e. 4 months after steroid discontinuation), nine patients (45%) were in remission on cyclophosphamide alone. However, patients that maintained treatment-free remission (cyclophosphamide responders) decreased to five (25%), two (10%) and one (5%) at 6 months, 1 year and 2 years, respectively. CONCLUSION: We found that a 6-month course of pulse cyclophosphamide produced unfavourable effects in the majority of paediatric patients with steroid-dependent nephrotic syndrome.     

Sequential studies of rat urinary bladder epithelial lesions induced by ifosfamide (Z4942)

Urinary bladder damage caused by ifosfamide in male F344 rats was studied by light microscopy and scanning electron microscopy. Ifosfamide was injected intraperitoneally at doses of 30, 60 and 120 mg. per kg. body weight, and rats were killed at several intervals following treatment. The changes in the epithelium observed by light microscopy and scanning electron microscopy following ifosfamide injection were compared to those observed following cyclophosphamide injection. Necrosis and exfoliation of the urinary bladder epithelium occurred after day 1 of ifosfamide treatment and were followed by regenerative hyperplasia. This hyperplasia was reversible. A dose response was evident in the number and size of lesions induced and the time of regeneration and repair. Scanning electron microscopy disclosed short, uniform microvilli on the luminal surface of cells during the early phases of hyperplasia. These microvilli persisted for only 1 day, from days 1 to 7, and days 1 to 12 respectively, following injection of 30, 60 and 120 mg. per kg. of ifosfamide. The hyperplastic lesions also contained cells with pleomorphic microvilli and ropy or leafy microridges on their surfaces. These findings after ifosfamide administration were similar to those reported to be induced in the urinary bladder by cyclophosphamide.     

ACNU-resistant mutants of 9L rat glioma cell line. Isolation and preliminary characterization of these subclones

Three ACNU-resistant subclones were isolated and characterized from a wild-typed 9L rat glioma cell line in culture. At an early stage after cloning, these ACNU-resistant subclones showed a high frequency of chromosomal aberrations compared with nonresistant 9L cells. These ACNU-resistant subclones revealed a cross resistance to BCNU, CCNU, methyl CCNU, nitrogen mustard, cyclophosphamide, and cis-platinum, which are alkylating agents. Further studies are necessary to clarify the mechanisms of ACNU-resistance from the aspect of repair of DNA alkylation damage.     

Elimination of alloantibodies by immunoablative high-dose cyclophosphamide

BACKGROUND: Alloimmunization is a major problem for patients being considered for solid organ transplantation and in patients who require blood transfusion support. We previously demonstrated that high-dose cyclophosphamide (200 mg/kg) without hematopoietic stem cell transplantation leads to durable complete remissions in aplastic anemia and other autoimmune disorders. We now examine the ability of high-dose cyclophosphamide to eliminate alloreactivity. METHODS: IgG-specific antibodies to HLA class I were assayed using enzyme-linked immunosorbent assays in 18 consecutive patients with severe aplastic anemia before and after treatment with high-dose cyclophosphamide. RESULTS: Anti-HLA antibodies were detected before or shortly after therapy in 5 of the 18 patients studied. Complete remission of aplastic anemia was achieved in four of these five patients. High-dose cyclophosphamide markedly reduced anti-HLA antibody titers in these four patients; they were completely eradicated in three patients. Only one patient did not achieve significant reduction in the alloantibody titer after high-dose cyclophosphamide. CONCLUSIONS: High-dose cyclophosphamide without stem cell transplantation can eradicate HLA-specific alloantibody.     

Cyclophosphamide rescue therapy for chronic rejection after lung transplantation.

BACKGROUND: Obliterative bronchiolitis remains the leading cause of late mortality after heart-lung and lung transplantation. Although several treatment options have been advocated, none has proven to be very successful. Cyclophosphamide is effective in the treatment of idiopathic pulmonary fibrosis, and chronic rejection after lung transplantation is also a fibroproliferative process. We therefore conducted an open, uncontrolled study to look at the effect of cyclophosphamide rescue therapy in the treatment of chronic rejection in lung transplant recipients. METHODS: Between October 1996 and March 1998 cyclophosphamide was prescribed to 7 patients with chronic and persistent rejection who failed to respond to conventional therapy (pulse steroids or antilymphocyte products or both). RESULTS: Cyclophosphamide therapy was initiated on postoperative day 478+/-366. At that time 2 patients were in bronchiolitis obliterans syndrome stage 0, 3 patients in stage 1, and 2 patients in stage 2. Their best postoperative forced expiratory volume in one second (FEV1) was 2.19+/-0.75 L. Three months before the start of cyclophosphamide the FEV1 had declined to 1.90+/-0.83 L, with a further decline to 1.63+/-0.64 L at the time of initiating cyclophosphamide. In 6 of the 7 patients the FEV1 stabilized or increased after cyclophosphamide had been started (mean FEV1 3 and 6 months after cyclophosphamide of 1.77+/-0.58 L and 1.79+/-0.48 L, respectively). One patient died 18 months after the introduction of cyclophosphamide due to progressive obliterative bronchiolitis. In one patient cyclophosphamide had to be stopped because of persistent leucopenia. CONCLUSIONS: Cyclophosphamide might be a promising therapeutic alternative for the treatment of chronic persistent rejection after lung transplantation.     

Restoration of hematopoiesis in dogs by infusion of cryopreserved autologous peripheral white cells following busulfan-cyclophosphamide treatment.

Canine cryopreserved autologous peripheral buffy coat cells were infused after an otherwise lethal regime of busulfan and cyclophosphamide. In seven dogs so treated, restoration of hematopoiesis occurred within 7 days, and six dogs recovered completely. Comparable colony-forming unit in agar activity was present in freshly processed and cryopreserved buffy coat cells and proved to correlate with in vivo marrow recovery. It was concluded that the peripheral blood is a convenient source for obtaining cells for autologous marrow reconstitution in canines.     

A case of adenocarcinoma of the renal pelvis

A 28-year-old female had adenocarcinoma arising from the renal pelvis with ascites containing adenocarcinoma cells. The primary site was treated with radical nephrectomy, resection of the remnant ureter with a bladder cuff. Combination chemotherapy with cisplatin, doxorubicin, and cyclophosphamide (CAP) was performed as an adjuvant therapy. Approximately 3 years after the nephrectomy, she is currently alive with no clinical evidence of recurrence. CAP seems to have been effective in the treatment of the disease.     

Long-term treatment of chronic lymphocytic leukemia in a green-winged macaw (Ara chloroptera)

A 32-year-old green-winged macaw (Ara chloroptera) was diagnosed with chronic lymphocytic leukemia based on progressive lymphocytosis and the presence of a monomorphic population of well-differentiated lymphocytes in the bone marrow of a clinically normal bird. Chemotherapy was initiated because of rapidly increasing peripheral lymphocyte counts. In addition to oral prednisone (1 mg/kg once daily), oral chlorambucil (1 mg/kg twice weekly) was initiated but was discontinued after 6 weeks because of thrombocytopenia. The leukocyte count was stabilized for 29 weeks with the concurrent use of oral cyclophosphamide (5 mg/kg 4 d/wk) and daily prednisone, and the bird exhibited a good quality of life. The bird died shortly after the chemotherapy was inadvertently discontinued. The neoplastic cells from this macaw stained positive for CD-3 antibody and negative for Bla.36, suggesting the leukemia was of T-cell origin. This is the first report of long-term treatment of a macaw with cyclophosphamide and documents thrombocytopenia in a macaw secondary to chlorambucil treatment.     

Treatment course of steroid‐dependent nephrotic syndrome: Emphasized on treatment effect

Aim: Children with steroid‐dependent nephrotic syndrome (SDNS) need long‐term steroid usage to maintain sustained remission. Cyclophosphamide is a well‐known alternative agent to spare the use of steroids and avoid the side‐effects that result from long‐term steroid therapy. Most children may continue to have SDNS despite receiving cyclophosphamide. Additional alternative drugs may be needed. In the present study, the effects on SDNS of sequential treatment after cyclophosphamide usage were established. Methods: Forty‐six children with SDNS were enrolled in this retrospective uncontrolled study. In addition to prednisolone, patients were treated with cyclophosphamide as a first‐line alternative drug. Children who still had SDNS despite cyclophosphamide therapy received chlorambucil, levamisole or another course of cyclophosphamide. The treatment responses were recorded and the mean duration of follow up was 96 months. Results: Seventeen patients (37%) experienced no relapse after cyclophosphamide therapy. Twenty‐five patients (54%) had varied responses. Only four patients showed no effect. Children who still had SDNS despite cyclophosphamide therapy received second or more alternative drugs. Cyclophosphamide with or without chlorambucil resolved steroid‐dependency in 33 of 46 (72%) children who either had complete remission or developed steroid‐sensitive, rather than steroid‐dependent, nephrotic syndrome. Conclusion: With the exception of four patients who were lost to follow up and four who were refractory and needed other treatment, most children with SDNS could spare the steroid (complete remission or steroid sensitive nephrotic syndrome) after using one or more of these modulating agents.     

Pathological changes associated with topical chemotherapy for superficial bladder cancer

With use of previous observations in experimental animals as a basis for comparison the cytologic and histologic changes in human patients who underwent topical chemotherapy for superficial bladder cancer were documented. Despite the potential for inhibition of deoxyribonucleic acid replication these drugs apparently act in vivo as toxic substances, causing increased exfoliation with denudation of papillary and/or flat urothelium. Multinucleation was common but confined to superficial cells. Atypical cells, such as those observed after systemic chemotherapy with cyclophosphamide, rarely were present and could be distinguished readily from neoplastic elements. Although topical chemotherapy may suppress tumor growth and progression it apparently does not eradicate the neoplastic process.