Halothane potentiates the antitumor activity of gamma-interferon and mimics calmodulin-blocking agents

This study reports effects of halothane on tumor cells in vitro. Cells from the human colon cancer cell line HT-29 were exposed to various concentrations of halothane for 8-72 h. The effect of this exposure on this colon cancer cell line, with and without coincubation with the biologic response modifier gamma-interferon (IFN-gamma), was studied. Using the tumor target cell survival (TTCS) assay, concentrations of halothane from 0.5 to 2% markedly augmented the antitumor activities of IFN-gamma against HT-29. The tumor cell cytostatic effects of IFN-gamma in the 0.75-6-unit/ml range were increased nearly 400% by concentrations of halothane as low as 1%. These results were confirmed in a separate cytolytic assay (Indium-111 release assay), which revealed that halothane concentrations in the 2-4% range markedly increased the cytolytic capacity of IFN-gamma at doses of IFN-gamma between 75 and 1,250 units/ml. The cytolytic activity of IFN-gamma was increased nearly 300% by doses of halothane as low as 1%. A nearly identical pattern of augmentation of IFN-gamma-induced antitumor activity was observed when the known calmodulin inhibitor trifluoperazine (TFP) was coincubated with IFN-gamma. At concentrations of 4-10 microM, the antitumor activity of IFN-gamma was increased nearly 400%. These observations suggest that the pattern of halothane potentiation of the antitumor activity of IFN-gamma is similar to that exhibited by known calmodulin inhibitors.     

Protein-calorie malnutrition inhibits antitumor response to interleukin-2 immunotherapy

The efficacy of systemic interleukin-2 (IL-2) immunotherapy is dependent on a competent host immune response. This study demonstrated that protein-calorie malnutrition (PCM) inhibited the generation of an antitumor response to IL-2. A/J mice received an isocaloric diet of 2.5% or 24% casein 8 weeks before inoculation with C1300 neuroblastoma cells. Three weeks later lymphocytes from tumor-bearing mice were harvested for determination of cytotoxic T-lymphocyte generation and natural killer cell cytotoxicity. PCM produced a significant reduction in total body weight (p less than 0.001) and serum albumin concentration (p less than 0.001). PCM inhibited generation of cytotoxic T lymphocytes (p less than 0.001), T-lymphocyte response in mixed lymphocyte reaction (p less than 0.001), and in vitro activation of natural killer cell cytotoxicity with IL-2 (p less than 0.001). A second experiment was performed to evaluate whether the in vitro deficits in tumor-specific and natural immunity in the animal model of PCM would diminish the efficacy of systemic high-dose IL-2 (3 x 10(6) units/kg three times daily for 5 days). The mean percent inhibition of C1300 growth with IL-2 was only 15% in mice with PCM compared with 60% in well-nourished mice (p less than 0.01). Median host survival time was greater in well-nourished animals (55 days) compared with animals with PCM (39 days) that received IL-2 (p less than 0.05). These data suggest that nutritional status is a critically important variable in tumoricidal response to systemic IL-2.     

Synergistic interleukin-18 and low-dose interleukin-2 promote regression of established murine neuroblastoma in vivo

Background/Purpose: Severe systemic toxicities have limited the clinical applications of the potent cytokine, interleukin-2 (IL-2). Recent studies have shown that IL-18 synergizes with IL-2 to enhance cytolytic activity in vitro. Combination therapy allows for IL-2 dose reduction, thus, limiting its toxicity while augmenting natural killer cell activity. The authors hypothesize that IL-18 plus low-dose IL-2 may induce a potent and sustained antitumor response in vivo providing effective immunotherapy for neuroblastoma. Methods: Four groups of A/J mice (n = 28) were inoculated subcutaneously in the right flank with 1 [times ] 10⁶ murine neuroblastoma cells (TBJ). On day 7, 5 consecutive daily peritumoral injections were performed with saline (control), human rIL-2 (30,000 IU), murine IL-18 (1 [mu ]g), or IL-2 plus IL-18. Tumor growth was monitored, and animals with tumor progression were killed on day 21. Seven weeks after the initial treatment, animals with rejected tumors were rechallenged with 5 [times ] 10⁶ cells in the opposite flank. Quantitative data were analyzed by Student's t test. Results: Rapid tumor growth and death was noted in all control animals by 21 days. Complete tumor eradication was seen in 28% of mice treated with IL-2 (P = .03), 42% of mice treated with IL-18 (P [lt ] .05), and 57% of mice treated with of IL-2 plus IL-18 (P [lt ] .05). Despite the initial response, all animals failed rechallenge and developed new or recurrent tumors within 7 to 10 days. Conclusions: Coadministration of low-dose IL-2 plus IL-18 induced a potent primary response to murine neuroblastoma likely caused by activation of natural killer cells in the tumor microenvironment. This combined cytokine therapy strategy was unable to induce sustained immunity to rechallenge. However, dendritic cell vaccination combined with IL-2 plus IL-18 cytokine treatment did allow for the establishment of a complete and durable antitumor response. J Pediatr Surg 38:301-307.     

Effect of antitumor surgery on soluble interleukin-2 receptor serum levels.

Surgically induced immunosuppression may play a role in cancer, because of the possible existence of micrometastases at the time of surgical removal of tumors. Antitumor immune reactions are mediated by interleukin-2 (IL-2). IL-2 acts on a specific IL-2 cell surface receptor; moreover, a soluble form of IL-2 receptor (sIL-2R) can be released in the blood. This study was carried out to evaluate the effect of surgery on sIL-2R serum levels in patients with operable solid tumors. A total of 48 patients with cancer and 11 controls who underwent major surgery for non-neoplastic disease were evaluated before and 7 days after surgery. Serum mean levels of sIL-2R were significantly higher after than before surgery in both the cancer and control groups. No correlation was seen between surgery-induced changes in sIL-2R and in T lymphocyte subsets. Because of its capacity of binding to IL-2, the increased blood concentrations of sIL-2R could reduce the IL-2 availability and negatively affect antitumor immune reactions.     

表达趋化因子MIP-1α的小鼠肝癌疫苗抗肿瘤活性的研究

目的　探讨小鼠趋化因子 (mMIP 1α)的重组腺病毒载体 (AdmMIP 1α)体外感染肝癌细胞株Hepa1 6后 ,其体内抗肿瘤活性及其成为肝癌疫苗的可能性。　方法　腺病毒载体体外感染Hepa1 6细胞 ,通过绿色荧光蛋白 (GFP)的表达检测感染效率 ;每天细胞计数 (连续 14d)观察细胞的体外生长曲线 ;取 5× 10 6个修饰后的Hepa1 6细胞接种C5 7BL/ 6小鼠 ,4周后在AdmMIP 1α组未荷瘤小鼠原接种部位的对侧再接种 2× 10 6个野生型Hepa1 6或EL4细胞 ,观察肿瘤大小并作统计学处理。结果　AdmMIP 1α能有效感染靶细胞Hepa1 6 ,感染前、后Hepa1 6的体外生长无明显改变 ;修饰后Hepa1 6细胞的体内成瘤性下降 ;4周后再接种Hepa1 6细胞 ,肿瘤生长速度显著降低 ;而再接种的EL4细胞呈渐进性生长 ,与对照组差异无显著意义。　结论　表达mMIP 1α基因的肝癌细胞的体内成瘤性下降 ,能激发特异性免疫保护反应 ,有可能成为有效的肝癌疫苗。     

Enhanced in vivo therapy of pulmonary metastases with interferon and interleukin-2

Interleukin-2 (IL-2) can mediate in vivo tumor regression at high doses. To enhance this efficacy, we studied the effect of adding a human hybrid recombinant interferon alpha A/D (rHuIFN-alpha-A/D) because of its known in vitro augmentation of immune-mediated tumoricidal activity. C56BL/6 mice bearing established pulmonary metastases induced by the iv injection of the methylcholanthrene-induced fibrosarcoma MCA 106 were treated for 12 days with intraperitoneal injections of (1) Hanks' balanced salt solution, (2) recombinant IL-2, (3) rHuIFN-alpha-A/D, and (4) a combination of IL-2 and HuIFN-alpha-A/D. IL-2 and interferon each had some antitumor activity. However, maximal reduction of pulmonary metastases consistently resulted from combining IL-2 with interferon. In two of four experiments, this combination was significantly better compared to either IL-2 or interferon treatment alone. The most potent regimen was 12 days of IL-2 (50,000 units bid) together with rHuIFN-alpha-A/D (50,000 units ip qd). No consistent pattern of proliferative or cytotoxic activity was found against a panel of stimulator and target cells. These results demonstrate enhanced antitumor efficacy of combining recombinant interferon alpha and IL-2 against established pulmonary metastases. Potential clinical applications are suggested by these data.     

The induction of specific antitumor immunity by in vivo treatment with interleukin-1 and sonicated tumor extract in a murine model

BALB/c mice were pretreated intraperitoneally with interleukin-1 (IL-1) and sonicated tumor extract (SE) from plasmacytoma MOPC104E, 10, 7, and 4 days prior to the intraperitoneal or subcutaneous inoculation of MOPC104E cells, following which significant suppression was observed. The mean survival time and tumor diameter on day 21 were 46.7 days and 0 mm, respectively, in contrast to the 20.9 days and 20.4 mm of control mice. Mice pretreated with IL-1 and SE from MOPC104E (MOPC-SE) were not suppressed following fibrosarcoma MethA inoculation, which indicates the tumor specificity of immunity in this model. This systemically operating antitumor immunity was also achieved by the intramuscular administration of IL-1, or when tumor challenge was performed on day 7 or 14. Moreover, MOPC104E-specific delayed-type hypersensitivity was detected in these mice. The results of this study suggest the possibilities of a new type of active specific immunotherapy, which could prove useful as postsurgical adjuvant therapy for cancer patients.     

Tamoxifen sensitivity-testing of glioblastomas: comparison of in vitro and in vivo results

Summary  Background. Only less than half of the patients with malignant gliomas respond to a continuous high dose Tamoxifen (TAM) and/or Carboplatin (CP)-treatment. Therefore, a method for predicting the efficacy of TAM-treatment would be desirable.  Methods. Paralleling a clinical study, the predictive value of in vitro-sensitivity testing of TAM and TAM's metabolite 4-OH-TAM in primary cultures of tumour explants from 15 of a total of 50 patients was examined. Additionally, the influence of TAM, 4-OH-TAM, and CP on the proliferation of established glioblastoma cell lines and of those explanted from athymic nude mice and re-established in cell culture was investigated. Human glioblastomas xenotransplanted subcutaneously into athymic nude mice and subsequently treated with TAM and/or CP were examined in a parallel in vivo-study.  Findings. TAM-chemosensitivity-testing of glioblastomas failed to predict the clinical response to TAM-treatment in our patients and did not correlate with the in vivo-TAM-response of tumours xenotransplanted into nude mice. TAM's and 4-OH-TAM's ability to inhibit growth of various glioblastoma cell lines in vitro in very similar concentrations was shown to be a consistent phenomenon which seems to be independent of the in vivo response in either patients or mice as previous hosts. However, CP's antiproliferative effect on glioblastomas in vivo was paralleled by respective in vitro results. Whereas TAM showed to mediate its in vitro antiproliferative effect by inducing apoptosis in most cell lines examined, CP-treatment lead to necrosis of cells.  Interpretation. Combining the results obtained from our human and mouse studies, it has to be postulated that host factors other than the sensitivity to TAM of the individual cell, determine the efficacy of TAM-treatment in vivo.     

Interleukin-2 transfected prostate cancer cells generate a local antitumor effect in vivo

In an effort to stimulate host-mediated antitumor response against prostate cancer in an animal model, highly malignant Dunning MAT-LyLu rat prostate carcinoma cells were transfected with the interleukin-2 (IL-2) cDNA, resulting in their ability to secrete large amounts of biologically active IL-2. Although parental cells form lethal tumors when injected subcutaneously into syngeneic hosts at doses of ≥5,000, injections of IL-2 secreting cells initially formed tumors and regressed completely in each of over 200 animals at all doses tested (10⁴-8 × 10⁷ cells). Mixtures of parental and IL-2 transfected cells were similarly rejected, demonstrating the non-cell autonomous nature of the response. Histological analysis of regressing tumors revealed a vigorous, predominantly lymphocytic and macrophage infiltrate at day 2 and marked tumor necrosis by day 6. Immunohistochemical staining of infiltrating lymphocytes at this latter time point demonstrated numerous T cells bearing either CD4 or CD8 surface markers, suggesting these cells as possibly mediating the tumor rejection. The ability of athymic mice to reject the IL-2 secreting tumor cells, however, suggests a non-T-cell-mediated mechanism. Although splenic natural killer (NK) activity is increased following injection of IL2 secreting tumor cells, this activity appears to be unnecessary for tumor elimination since syngeneic animals injected with asialo-GM1 antiserum to decrease NK activity also rejected IL-2 transfected cells, albeit slightly less effectively than untreated animals. Immunization of animals with subcutaneous injections of IL-2 transfected cells protected animals against a subsequent challenge of 10⁴ wild-type cells 1 to 2 weeks later in 19 of 51 cases; however, immunization did not confer protection against larger doses of parental tumor. These studies indicate that high local concentrations of IL-2 stimulate the elimination of large local burdens of prostate cancer in this model system, and this elimination results in a weak, but detectable systemic immune response against wild-type prostate cancer cells. © 1994 Wiley-Liss, Inc.     

Ex vivo expanded human Vgamma9Vdelta2+ gammadelta-T cells mediate innate antitumor activity against human prostate cancer cells in vitro

PURPOSE: We have previously identified a CD2 mediated, interleukin-12 dependent signaling pathway that inhibits activation induced cell death in mitogen stimulated human gammadelta-T cells, permitting the large-scale expansion of these cells. Herein we report the innate antitumor activity of expanded human Vgamma9Vdelta2+ gammadelta-T cells against human prostate cancer cells. MATERIALS AND METHODS: Apoptosis resistant human gammadelta-T cells were expanded in vitro from cultured human peripheral blood mononuclear cells and then enriched to high purity by immunomagnetic separation. In vitro cytotoxicity of expanded gammadelta-T cells was measured against human prostate cancer cell lines using standard cytotoxicity assays. RESULTS: gammadelta-T cells derived from various donors consistently showed lytic activity against the prostate cancer cell lines DU-145 and PC-3 but not LNCaP. mAbs against Vgamma9 or Vdelta2 T-cell receptor chains as well as mAb against intercellular adhesion molecule-1 (ICAM-1) or CD18, the beta subunit of ICAM-1 counter receptors, blocked gammadelta-T cell mediated killing of prostate cancer cells. gammadelta-T cells lysed prostate cancer cell lines largely through the perforin/granzyme pathway. CONCLUSIONS: Ex vivo, expanded human Vgamma9Vdelta2+ gammadelta-T cells are able innately to recognize and kill certain human prostate tumor cell lines in vitro. The recognition and killing of prostate cancer cells occurs in a gammadelta-T-cell receptor dependent manner and it also appears to involve interactions between ICAM-1 and CD18. Because apoptosis resistant human Vgamma9Vdelta2+ gammadelta-T cells can readily be expanded to large numbers (clinical scale), these findings must be considered in the context of developing adoptive immunotherapy strategies to exploit gammadelta-T cell innate immune responses to prostate cancer.     

Recombinant human bone morphogenetic protein-2 potentiates the in vivo osteogenic ability of marrow/hydroxyapatite composites

A composite of marrow mesenchymal stem cells (MSCs) and porous hydroxyapatite (HA) has bone-forming capability. To promote the capability, we added recombinant human bone morphogenetic protein-2 (BMP) to the composite. The bone formation was assessed by rat subcutaneous implantation of 4 different kinds of implants, i.e., HA alone, BMP/HA composites, MSCs/HA composites, and the composites containing BMP (MSCs/BMP/HA). Both HA and the BMP/HA composites did not show bone formation at any time after implantation. The MSCs/HA composites showed moderate bone formation at 4 weeks and extensive bone formation at 8 weeks. The MSCs/BMP/HA composites showed obvious bone formation together with active osteoblasts at 2 weeks and more bone formation at 4 and 8 weeks. The MSCs/BMP/HA composites demonstrated high alkaline phosphatase and osteocalcin expression at both the protein and gene levels. These results indicate that the combination of MSCs, porous HA, and BMP synergistically enhances osteogenic potential and provides a rational basis for their clinical application in bone reconstruction surgery.     

Successful combination immunotherapy for the generation in vivo of antitumor activity with anti-CD3, interleukin 2, and tumor necrosis factor alpha

The purpose of this study was to generate lymphokine-activated killer cells via alternative pathways using combinations of biologic agents. Immunotherapy with the mouse anti-CD3 analogue combined with low-dose interleukin 2 (IL-2) and tumor necrosis factor alpha (TNF-alpha) was tested for in vivo antitumor efficacy against established pulmonary metastases from a variety of mouse tumor-cell lines. Administration of a single dose of anti-CD3 followed by low-dose IL-2 and TNF-alpha potentiated reduction of metastases compared with higher doses of IL-2 alone or IL-2 plus TNF-alpha. Treatment with anti-CD3 plus IL-2 plus TNF-alpha significantly prolonged survival and resulted in 60% of the mice achieving long-term survival compared with no survival using single agents or other combinations. The lymphokine-activated killer and natural killer activities of mouse splenocytes increased following treatment with anti-CD3 plus IL-2 plus TNF-alpha. These results indicate that the sequential use of anti-CD3, IL-2, and TNF-alpha for the induction and maintenance of lymphokine-activated killer activity potentiates antitumor activity and provides novel strategies for combination immunotherapy.     

In vivo effect of interleukin-2 (IL-2) on immunopotentiation in irradiated mice]

This study's purpose was to evaluate the effect of IL-2 on the recovery from immunosuppressive state in vivo. Young adult mice (ddY) were rendered immunodeficient by whole body irradiation (300 rad). IL-2 (20000 u/head/day) was administered intraperitoneally for 5 days after irradiation. In the experiment (I) immunological parameters were investigated. In the IL-2-treated mice peripheral lymphocytes and neutrophils were increased, but there was no change in the T and B lymphocyte ratio. The proliferative responses of spleen cells to mitogens were improved in the IL-2-treated mice. A significant expansion of macrophages in the intraperitoneal cavity was demonstrated. In the experiment (II) irradiated mice were given peritonitis by 1 puncture with a 23 gauge needle through their ligated cecum. This peritonitis model was followed for 2 weeks after ligation and puncture of the cecum. In the mice with IL-2 pretreatment and antibiotic therapy, the survival rate was significantly improved, compared with mice that only received antibiotic therapy. Administration of carrageenan and anti-T cell monoclonal antibodies significantly decreased the survival rate. These results suggested macrophages as well as functional T cells were necessary to decrease the mortality rate. In conclusion, IL-2 may have a remarkably protective effect against infection in immunodeficient state.     

白细胞介素-2基因修饰树突状细胞体外增强其诱导的抗肝癌免疫反应

目的探讨腺病毒介导的白细胞介素(IL)-2基因修饰能否使抗原冲击的树突状细胞(DC)在体外诱导出更强的抗肝癌免疫反应。方法IL-2的重组腺病毒载体体外转染经肝癌细胞株HepG2冻融抗原致敏的DC(AdIL-2-HepG2/DC),FACS分析AdIL-2-HepG2/DC表面分子的表达,酶联免疫吸附试验法(ELISA)检测IL-2水平,3H-TdR掺入法检测T淋巴细胞增殖分化能力,噻唑蓝(MTT)法检测细胞毒性T淋巴细胞(CTL)效应。结果AdIL-2-HepG2/DC能高水平的表达CD1a(61.7±8.1)%,CD11c(72.9±6.2)%,CD80(81.1±7.1)%,CD86(76.4±6.8)%以及HLA-DR(90.6±6.4)%,并分泌较高水平的IL-2(6.78±0.18)mq/L。AdIL-2-HepG2/DC能非常显著地刺激自体T细胞增殖(CPM值为21 878±1089),当靶细胞为HepG2时,其诱导的CTL杀伤活性(74.5±3.8)%显著高于其他各组,并且其杀伤能力与效应细胞数量成正比。结论AdIL-2- HepG2/DC可以增强体外诱导的特异性抗肝癌免疫反应。     

The modulation by L-leucovorin of 5-fluorouracil antitumor activity on human colon carcinoma cells in vitro and in vivo

We investigated the modulating effect of L-leucovorin (LV) on the antitumor effect of 5-fluorouracil (5-FU) against human colon carcinoma cells (C-1) in vitro and human colon carcinoma xenografts (Co-4) in nude mice. The modulating effect of LV on 5-FU reached an optimal concentration of 40–80 g/ml in vitro which was detected by a colorimetric MTT assay. An optimal dose of 200 mg/kg was also observed in the nude mouse system. The modulating effect of LV increased according to the increment of thymidylate synthetase inhibition in vivo. Since the pharmacokinetic pattern of LV in the nude mice administered LV at 200 mg/kg was similar to that in patients treated with LV at a dose of 100 mg/m², this clinical method of administration was thought to be adequate for modulating the antitumor activity of 5-FU against clinical colon carcinomas.     

Bone marrow-derived heparan sulfate potentiates the osteogenic activity of bone morphogenetic protein-2 (BMP-2)

Lowering the efficacious dose of bone morphogenetic protein-2 (BMP-2) for the repair of critical-sized bone defects is highly desirable, as supra-physiological amounts of BMP-2 have an increased risk of side effects and a greater economic burden for the healthcare system. To address this need, we explored the use of heparan sulfate (HS), a structural analog of heparin, to enhance BMP-2 activity. We demonstrate that HS isolated from a bone marrow stromal cell line (HS-5) and heparin each enhances BMP-2-induced osteogenesis in C2C12 myoblasts through increased ALP activity and osteocalcin mRNA expression. Commercially available HS variants from porcine kidney and bovine lung do not generate effects as great as HS5. Heparin and HS5 influence BMP-2 activity by (i) prolonging BMP-2 half-life, (ii) reducing interactions between BMP-2 with its antagonist noggin, and (iii) modulating BMP2 distribution on the cell surface. Importantly, long-term supplementation of HS5 but not heparin greatly enhances BMP-2-induced bone formation in vitro and in vivo. These results show that bone marrow-derived HS effectively supports bone formation, and suggest its applicability in bone repair by selectively facilitating the delivery and bioavailability of BMP-2.     

Specific antitumor effect of lymphokine-activated lymphocytes obtained from tumor-bearing mice after intratumoral injection of interleukin-2 (IL-2)

Specific antitumor effects of lymphokine-activated lymphocytes obtained from tumor-bearing mice after intratumoral injection of IL-2 were studied. Inbred C57BL/6 mice bearing syngeneic tumor (B16,3LL) were used. After intratumoral consecutive injection of recombinant human IL-2 (rhIL-2), the splenocytes of these mice were cultured with rhIL-2 and the effector cells were obtained. Specific antitumor effects of the effector cells against B16 and 3LL were studied in vitro and in vivo. Surface antigens of them were also analysed. The results were as follows: 1) 51Cr-release test under coculture with rhIL-2 showed that cytotoxicity against the host tumor cells with the effector cells became specifically augmented. 2) Winn assay showed specific inhibition of the host tumor growth with the effector cells. 3) Adoptive transfer of te effector cells specifically diminished the size of the host tumor and prolonged the life span of the mice. 4) The lymphokine-activated lymphocytes obtained from normal and non-treated tumor-bearing mice had no specific antitumor effect. 5) The analysis of the surface antigens indicated that Thy1.2+L3T4+ T cells increased in the effector cells as the specific cytotoxicity of them were augmented, while in the effector cells from normal and non-treated tumor-bearing mice, Thy1.2+L3T4+ T cells decreased and Thy1.2+Lyt2+ T cells increased.     

In vivo effect of 1 alpha-hydroxyvitamin D3 on interleukin-2 production in hemodialysis patients

The immunoregulatory effect of 1 alpha-OHD3, a precursor form of active vitamin D3 1,25 (OH)2D3, was examined in hemodialysis patients. Peripheral blood mononuclear cells (PBM) from hemodialysis patients produced significantly less interleukin-2 (IL-2) than those from normal controls. Four weeks of oral administration of 0.5 micrograms/day of 1 alpha-OHD3 enhanced the IL-2 production of PBM from the patients. This fact suggests that 1 alpha-OHD3 therapy may be useful for the restoration of IL-2 production in hemodialysis patients, and that the vitamin D3 deficiency may be responsible for the impairment of cellular immunity associated with IL-2 production disorder in hemodialysis patients.     

Laparotomy enhances intraperitoneal tumor growth and abrogates the antitumor effects of interleukin-2 and lymphokine-activated killer cells

The interrelationship between host resistance to cancer and the trauma of a surgical procedure is the subject of much speculation. Extensive study of animal models and human subjects is required to define these effects and to provide a theoretical model by which to interpret these data. We used a murine model of intraperitoneal cancer to demonstrate the augmentation of tumor growth by surgical trauma. In this intraperitoneal tumor model, a surgical procedure that included entry into the abdominal cavity resulted in augmented tumor growth; a surgical incision on the skin of the animal's back did not promote tumor growth. The immunotherapeutic effects of interleukin-2 and lymphokine-activated killer cells were significantly reduced by the performance of a laparotomy. This abrogation of the effects of the immunotherapeutic regimen was observed for up to 14 days after laparotomy but was lost by days 35 to 42. Healing tissue may promote tumor growth, and these effects are dominant over immunotherapy with interleukin-2 plus lymphokine-activated killer cells.     

L-buthionine sulfoximine potentiates the antitumor effect of 4-hydroperoxycyclophosphamide when administered locally in a rat glioma model

OBJECTIVE: L-buthionine sulfoximine (BSO) inhibits glutathione synthesis and may modulate tumor resistance to some alkylating agents, but it has not been proven effective in the treatment of intracranial neoplasms. To evaluate this drug for the treatment of brain tumors, we studied the use of BSO for potentiating the antineoplastic effect of 4-hydroxyperoxycyclophosphamide (4-HC) in the rat 9L glioma model. METHODS: The survival of male Fischer 344 rats with intracranial 9L gliomas was measured after implantation of controlled-release polymers containing one of the following: no drug, BSO, 4-HC, or both BSO and 4-HC. The efficacy of intracranial 4-HC treatment was assessed with and without serial systemic intraperitoneal BSO injections. Tissue glutathione levels were measured in the brains, tumors, and livers of animals treated with intraperitoneal injections or local delivery of BSO. RESULTS: The median survival of animals treated with intracranial polymers containing 4-HC was 2.3 times greater than that of controls. This survival benefit was doubled by local delivery of BSO. In contrast, systemic BSO therapy did not improve survival time. In animals that were treated systemically, both liver and tumor glutathione levels were significantly lower than they were in control animals. In the locally treated animals, glutathione levels were reduced in the brain tumor but not in the liver. CONCLUSION: These results demonstrate that local but not systemic delivery of BSO enhances the antineoplastic effect of 4-HC in this rat 9L glioma model. In addition, because local delivery of BSO within the brain did not deplete glutathione levels systemically, this method of treatment may be safer than systemic administration of BSO.