Immunological responsiveness to interleukin-2-producing brain tumors can be restored by concurrent subcutaneous transplantation of the same tumors

The central nervous system shows tolerance for activated host immune reactions, and this relative unresponsiveness may lessen the efficacy of an immunotherapy for brain tumors. Using interleukin-2 (IL-2)-producing 9L rat gliosarcoma cells (9L/IL-2), we examined whether secretion of IL-2 from subcutaneous (s.c.) and/or intracerebral (i.c.) tumors can elicit augmented immunological responses to brain tumors. Syngeneic rats could reject 9L/IL-2 cells inoculated s.c., but developed 9L/IL-2 brain tumors by i.c. inoculation. The growth of i.c. 9L/IL-2 tumors was, however, significantly retarded compared with that of i.c. wild-type tumors. The growth of i.c. wild-type tumors was significantly suppressed when the rats concurrently received 9L/IL-2 cells s.c. Moreover, most of the rats that were inoculated i.c. with 9L/IL-2 cells did not develop brain tumors when concurrently injected s.c. with 9L/IL-2 cells. Immunohistochemical analysis on i.c. 9L/IL-2 tumors, when the rats were concurrently inoculated s.c. with 9L/IL-2 cells, revealed that migration of CD4+ or CD8+ T cells, monocytes/microglias, and macrophages was markedly augmented to a similar level as found in the s.c. 9L/IL-2 tumors. These results showed that systemic immune responses to brain tumor were induced in an immunologically privileged site by concurrent s.c. inoculation of the same tumors that produce IL-2. The present study may also raise the possibility of a therapeutic strategy for brain tumors by the combinatory expression of IL-2 gene using s.c. immunization followed by direct gene transfer into brain tumors.     

Induced immunity by expression of interleukin-2 or GM-CSF gene in murine neuroblastoma cells can generate antitumor response to established tumors.

We examined whether antitumor immunity could be generated by the inoculation of cytokine-producing murine neuroblastoma cells (C1300), and whether the immunity might be effective for the established tumors of wild-type (wt) cells. For that purpose, we transduced low immunogenic C1300 cells with interleukin-2 (IL-2), GM-CSF, or IL-4 genes. A loss of tumorigenicity in syngeneic mice was observed using IL-2- and GM-CSF- but not IL-4-producing C1300 cells, although their in vitro growth rates were not affected by the transduction. The syngeneic mice that had rejected IL-2 or GM-CSF producers did not develop tumors of wt cells inoculated subsequently, but formed tumors of irrelevant syngeneic mammary tumor cells. Accordingly, the inoculation of IL-2 or GM-CSF producers into immunocompetent mice generated tumor-specific acquired immunity. The induced immunity using IL-2 or GM-CSF producers was also effective in eradicating established subcutaneous tumors of wt cells and in reducing the number of preexisting metastatic foci in the liver. These data suggest a potential application of IL-2- or GM-CSF-producing syngeneic tumor cells for the treatment of low immunogenic neuroblastomas.     

Polyethylene-glycol-modified interleukin-2 is superior to interleukin-2 in locoregional immunotherapy of established guinea-pig tumors.

Polyethylene glycol-modified recombinant human interleukin-2 (PEG-IL-2) represents a cytokine with prolonged circulatory half-life and increased antitumor activity as compared to recombinant interleukin-2 (rIL-2) after systemic administration. We studied whether PEG-IL-2 would also be advantageous in locoregional immunotherapy using a syngeneic tumor model. Intradermal inoculation of line-10 tumor cells into the flanks of strain-2 guinea-pigs results in a fast-growing tumor and regional lymph-node metastases. Treatment schedules were started on day 7 after inoculation in animals with established tumors. First, groups of 5-6 animals were treated with repeated intratumoral and perilymphatic rIL-2 or PEG-IL-2 injections. PEG-IL-2 caused significant growth inhibition of both the primary tumor and the regional lymph-node metastases at lower doses and with less frequent administration than rIL-2. The best schedule for PEG-IL-2 was 3 injections a week for 5 weeks, resulting in cure of 4/17 and 5/5 (p less than 0.01) animals at the 2 most efficient dose levels tested. Subsequent experiments indicated that the intratumoral and not the perilymphatic injection route was essential for the obtained antitumor effect. Furthermore, 12/12 animals cured after PEG-IL-2 treatment rejected a rechallenge with line-10 tumor cells, whereas no cures were seen after rIL-2 injections. PEG-IL-2 therefore appears to be a valuable substance for intratumoral immunotherapy.     

Intralesional immunotherapy of brain tumors with combined Corynebacterium parvum and recombinant interleukin-2 in mice

Clinical observations and experimental work suggested that inflammatory cells attracted to the brain exert a nonspecific antineoplastic effect. Intralesional treatment of implanted malignant murine brain tumors (KHT sarcomas) with killed Corynebacterium parvum produced an inflammatory cell infiltrate and increased survival in C3H mice relative to that in untreated control C3H mice. This antitumor effect was enhanced when recombinant interleukin-2 was sequentially added as a second intralesional immunomodifier. A high percentage of mice so treated were cured. Inflammatory cells in the brains of treated mice divided for 1-2 weeks, and metabolic activity of astrocytes increased. These findings form the basis for a recently initiated immunotherapy protocol in patients with recurrent glioblastoma multiforme.     

自身造血干细胞移植术联合小剂量白介素-2治疗16例恶性淋巴系统肿瘤

目的评价自体外周血造血干细胞移植(Auto-PBSCT)联合小剂量白介素-2(IL-2)在恢复细胞免疫,从而减少淋巴系统恶性肿瘤(ALL和NHL)移植后的高复发率和提高无病生存率中的作用.方法采用化疗联合短程小剂量G-CSF的动员方法,收集自体外周血造血干细胞,对16例成人淋巴源性恶性血液肿瘤(7例CR1ALL、3例CR1 NHL、5例难治性NHL和1例CR2 ALL)进行移植,使用IL-2对移植物进行温育,移植术造血恢复过程中使用IL-2和造血恢复后长期小剂量使用IL-2 5万U/d.结果ALL 7例CR1,现仍存活,平均生存时间达73个月,中位生存期为51.5个月,3例CR1 NHL2例仍存活,10例CR1恶性淋巴系肿瘤的6年无病生存率达0.90±0.11,其95%CI为0.71～0.99.而难治性NHL和CR2-ALL,1例至今仍无病生存达63月.1例淋巴母细胞IV期NHL生存达46个月后复发死亡.这组3年无病生存率只有0.33±0.18, 95%CI 0.02～0.64,平均生存时间只有20.66个月,中位生存期为6个月.结论通过小样本Auto-PBSCT联合长期小剂量IL-2可能有效地提高CR1淋巴系恶性肿瘤无病生存率.     

Recombinant Sendai virus vector induces complete remission of established brain tumors through efficient interleukin-2 gene transfer in vaccinated rats.

PURPOSE: Sendai virus (SeV), a murine parainfluenza virus type I, replicates independent of cellular genome and directs high-level gene expressions when used as a viral vector. We constructed a nontransmissible recombinant SeV vector by deleting the matrix (M) and fusion (F) genes from its genome (SeV/DeltaMDeltaF) to enhance its safety. We also estimated the therapeutic efficacy of the novel vector system against a rat glioblastoma model. EXPERIMENTAL DESIGN: We administered the recombinant SeV vector carrying the lacZ gene or the human interleukin-2 (hIL-2) gene into established 9L brain tumors in vivo simultaneous with peripheral vaccination using irradiated 9L cells. Sequential monitoring with magnetic resonance imaging was used to evaluate the therapeutic efficacy. RESULTS: We found extensive transduction of the lacZ gene into the brain tumors and confirmed sufficient amounts of interleukin 2 (IL-2) production by hIL2-SeV/DeltaMDeltaF both in vitro and in vivo. The magnetic resonance imaging study showed that the intracerebral injection of hIL2-SeV/DeltaMDeltaF brought about significant reduction of the tumor growth, including complete elimination of the established brain tumors. The (51)Cr release assay showed that significant amounts of 9L-specific cytotoxic T cells were induced by the peripheral vaccination. Immunohistochemical analysis revealed that CD4(+) T cells and CD8(+) T cells were abundantly infiltrated in the target tumors. CONCLUSION: The present results show that the recombinant nontransmissible SeV vector provides efficient in vivo gene transfer that induces significant regression of the established brain tumors and suggest that it will be a safe and useful viral vector for the clinical practice of glioma gene therapy.     

Induction of systemic immunity by expression of interleukin-23 in murine colon carcinoma cells

Interleukin-23 (IL-23), a novel cytokine composed of a newly identified p19 molecule and the p40 subunit of IL-12, can stimulate the proliferation in vitro of memory T cells. We examined whether Colon 26 murine colon carcinoma cells that were retrovirally transduced with the p19-linked p40 gene (Colon 26/IL-23) could produce antitumor effects in inoculated mice. The growth of Colon 26/IL-23 tumors developed in immunocompetent mice was significantly retarded and the tumors disappeared thereafter. Spleen cells from the mice that received Colon 26/IL-23 cells produced significant amounts of interferon-gamma, when they were cultured with irradiated Colon 26 but not irrelevant cells. Depletion of CD8(+) T cells suppressed the production of interferon-gamma. The mice that had rejected Colon 26/IL-23 tumors were resistant to subsequent challenge of parent but not irrelevant tumor cells. Colon 26/IL-23 tumors were not rejected in nude mice but the growth was retarded compared to parent tumors. Treatment of nude mice with anti-asialo GM(1) antibody did not influence the growth of Colon 26/IL-23 tumors. These data suggest that expression of IL-23 in tumors produces T cell-dependent antitumor effects and induces systemic immunity.     

Serum concentrations of soluble interleukin-2 receptor in patients with malignant brain tumors

BACKGROUND AND OBJECTIVES: Interleukin-2 receptor alpha (IL-2Ralpha) can combine with IL-2 firmly, and soluble IL-2Ralpha (sIL-2Ralpha) is elevated in sera from patients with various types of cancers. To investigate the role of this receptor, we studied the changes of serum sIL-2Ralpha in patients with malignant brain tumors. METHODS: SIL-2Ralpha was measured in 100 patients with malignant brain tumors (63 cancer metastasis, 16 malignant gliomas, 21 malignant lymphomas), and 51 patients with cancer who had no distant metastasis such as brain metastasis. RESULTS: In patients with 35 metastatic brain tumors from lung cancer, the levels of sIL-2Ralpha were not significantly different from levels in normal volunteers (311 +/- 62.4 U/ml). In patients with 25 metastatic brain tumors from lung adenocarcinoma, the mean level of serum sIL-2Ralpha was 352 +/- 94.0 U/ml. These same patients showed high levels of serum sIL-2Ralpha (492 +/- 101 U/ml) with regional lymph nodes metastasis. Serum sIL-2Ralpha concentration in 16 patients with malignant glioma varied greatly with the mean concentration of 328 +/- 192 U/ml. In 5 of 16 patients with malignant glioma, we could detect the significant increase of serum sIL-2Ralpha concentration from early stage of recurrence. CONCLUSIONS: Serum levels of sIL-2Ralpha could be a useful immunological marker in patients with malignant brain tumors.     

Induction of lymphokine-activated killer cells in strain 2 guinea pigs with human interleukin-2

Culture of spleen cells from strain 2 guinea pigs with Jurkat interleukin-2 (IL-2) resulted in the induction of lymphokine-activated killer (LAK) cells. Maximum LAK activity was induced using 5000 pmol of IL-2. Incubation of spleen cells with IL-2 for as little as 8 h resulted in detectable LAK activity. LAK cell activity was transient and could be stimulated by adding back IL-2. LAK cell activity was enriched in a 1.085 single-step percoll gradient. Admixture of guinea pig LAK cells with the line 10 hepatoma prior to intradermal injection resulted in inhibition of tumor growth. Systemic passive transfer of LAK cells together with concurrent IL-2 resulted in a significant inhibition of metastatic tumor growth.     

Regression of established tumors and induction of tumor immunity by intratumor chemotherapy.

The inoculation of a mixture of drugs and guinea pig hepatoma cells (line-10) induced tumor-specific immunity in about 20% of guinea pigs. When guinea pigs with established intradermal tumors were given various drugs ip, no cures were observed; in contrast, multiple intralesional injections of actinomycin D, 1,3-bis(2-chlorethyl)-1-nitrosourea, adriamycin, mitomycin C, and melphalan were effective in curing animals of their intradermal tumors at a time when there were tumor cells in the draining lymph nodes; dimethyl-triazenoimidazole carboxamide, methotrexate, 5-fluorouracil, and 6-mercaptopurine were not effective. More than 80% of the cured animals were immune to rechallenge with 10(6) line-10 tumor cells.     

Local low-dose interleukin-2 induces systemic immunity when combined with radiotherapy of cancer. A pre-clinical study

Tumor recurrence and outgrowth of metastases limit the therapeutical effect of radiotherapy. We have tested whether these problems can be overcome by supplementing radiotherapy with locoregional interleukin-2 (IL-2) treatment. The SL2 lymphoma and the M8013 mammary carcinoma were used. Mice bearing a 10-day-old s.c. tumor were locally irradiated and were treated daily with IL-2 peritumorally for 5 or 10 days. Low-dose IL-2 therapy improved local response (LR) and increased disease-free survival (DFS) in both tumor models following either single-dose irradiation or fractionated irradiation. For example, 93% of SL2-bearing mice treated with single-dose irradiation and 10 days of IL-2 experienced long-term DFS, compared with 17% for irradiation alone (p < 0.0001). Additionally, treatment of one tumor with irradiation +IL-2 led to anti-tumor effects in a second, untreated tumor in 80% of SL2-bearing mice. LR was increased to 100% and DFS to 70% when the second, non-irradiated tumor was also treated with peritumoral IL-2. We conclude that supplementing local radiotherapy with low doses of IL-2 results in increased local tumor control and regression of distant, non-irradiated tumors. This type of radioimmunotherapy is a promising new approach for the clinic. Int. J. Cancer 72:1003–1007, 1997. © 1997 Wiley-Liss, Inc.     

Effect of in situ retroviral interleukin-4 transfer on established intracranial tumors

BACKGROUND: Current therapies for malignant gliomas remain largely ineffective. We have previously demonstrated that interleukin 4 (IL-4) exhibits antitumorigenic activity in athymic nude mice by promoting both eosinophil infiltration and inhibition of tumor angiogenesis (formation of new blood vessels). In this study, we investigated treatment of established rat C6 cell gliomas by retroviral delivery of IL-4 in situ. METHODS: Tumors grown subcutaneously in athymic nude mice or implanted intracranially in immunocompetent Wistar rats were implanted with ecotropic retrovirus (i.e., will replicate only in cells of closely related species) packaging cells (RPCs) that were transfected with a retroviral vector encoding mouse IL-4 (1C5 cells) or a control vector (SV cells). For the demonstration of the long-term effects of such treatment, C6 cells were also implanted into the contralateral hemisphere of the brains of rats previously treated with 1C5 RPCs. Tumor volume measurements and immunohistochemical analyses were performed. RESULTS: Implantation of 1C5 RPCs into subcutaneous C6 cell tumors resulted in tumor growth arrest that was associated with eosinophil infiltration and inhibition of angiogenesis. When 1C5 RPCs were stereotactically implanted into established intracranial tumors in rats, tumor volumes were dramatically smaller than in control animals (approximately 1.8 mm3 versus 70-80 mm3, respectively) 7 days after treatment. All 1C5 RPC-treated rats survived to 106 days after C6 cell implantation (99 days after treatment; an arbitrary end point), whereas control rats had to be killed 14 days after C6 cell implantation because of extensive tumor growth. Histologic analysis demonstrated that treated tumors were completely eradicated, and immunohistochemical analysis revealed an inhibition of tumor angiogenesis and infiltration by CD8+ cells and macrophages. C6 cells implanted contralaterally into the brains of long-term-surviving rats treated with 1C5 RPCs were also rapidly and completely rejected. CONCLUSIONS: Implantation of packaging cells producing IL-4 retrovirus leads to rapid eradication of rat C6 cell gliomas and provides sustained protection against further intracranial challenge.     

Pivotal role of innate and adaptive immunity in anthracycline chemotherapy of established tumors

We show, in a series of established experimental breast adenocarcinomas and fibrosarcomas induced by carcinogen de novo in mice, that the therapeutic efficacy of doxorubicin treatment is dependent on CD8 T cells and IFN-γ production. Doxorubicin treatment enhances tumor antigen-specific proliferation of CD8 T cells in tumor-draining lymph nodes and promotes tumor infiltration of activated, IFN-γ-producing CD8 T cells. Optimal doxorubicin treatment outcome also requires both interleukin (IL)-1β and IL-17 cytokines, as blockade of IL-1β/IL-1R or IL-17A/IL-17Rα signaling abrogated the therapeutic effect. IL-23p19 had no observed role. The presence of γδ T cells, but not Jα18(+) natural killer T cells, at the time of doxorubicin treatment was also important. In tumor samples taken from breast cancer patients prior to treatment with anthracycline chemotherapy, a correlation between CD8α, CD8β, and IFN-γ gene expression levels and clinical response was observed, supporting their role in the therapeutic efficacy of anthracyclines in humans. Overall, these data strongly support the pivotal contribution of both innate and adaptive immunity in treatment outcomes of anthracycline chemotherapy.     

Analysis of interleukin-13 receptor alpha2 expression in human pediatric brain tumors

BACKGROUND: Compared with normal brain tissue cells, human malignant glioma cells express higher levels of interleukin-13 receptor (IL-13R). However, whether this receptor is expressed in situ has not been carefully examined. With IL-13R-targeted cytotoxin (IL13-PE38QQR, comprising IL-13 and a mutated form of Pseudomonas exotoxin [PE]) being tested in three Phase I/II clinical trials for the treatment of adult human glioma, and with pediatric studies being planned, the authors set out to analyze pediatric brain tumor tissue specimens for the expression of IL-13R. METHODS: Using in situ hybridization and immunohistochemical staining, the authors examined 58 pediatric brain tumor specimens for expression of the predominant IL-13 binding and internalizing protein (IL-13Ralpha2) chain at the mRNA and protein levels. RESULTS: Overall, approximately 83% of pediatric brain tumor samples expressed IL-13Ralpha2. One hundred percent (11 of 11) high-grade astrocytoma, 79% (26 of 33) low-grade astrocytoma, 67% (4 of 6) medulloblastoma, and 67% (2 of 3) ependymoma samples were positive for IL-13Ralpha2. Among IL-13Ralpha2-positive samples, 88% (42 of 48 samples) had positive expression in > or = 50% of all tumor fields. The results obtained using both assays were consistent with each other. CONCLUSIONS: The current study established that pediatric brain tumor specimens expressed the IL-13Ralpha2 chain. Because the IL-13Ralpha2 chain is a major binding component of the IL-13R complex, these results suggest that the targeting of IL-13R may represent a useful approach for the treatment of pediatric brain tumors.     

Recombinant vesicular stomatitis virus targeted to Her2/neu combined with anti-CTLA4 antibody eliminates implanted mammary tumors

Vesicular stomatitis virus (VSV) is being developed for cancer therapy. We created a recombinant replicating VSV (rrVSV) that preferentially infected Her2/neu expressing breast cancer cells. We now used this rrVSV to treat macroscopic peritoneal tumor implants of a mouse mammary tumor cell line stably transfected to express Her2/neu. rrVSV therapy alone prolonged survival but did not cure any animals. rrVSV therapy combined with antibody to TGFb or antibody to IL-10 receptor (IL-10R) each produced cure in one of six animals. Strikingly, rrVSV therapy combined with anti-CTLA4 monoclonal antibody (MAb) produced cure in four of five animals. Anti-CTLA4 MAb was only effective when administered within one day of rrVSV therapy. Cure required CD4 T-cells early (<7 days) and late (>7 days) after rrVSV therapy whereas CD8 T-cells were required only late (>7 days) after rrVSV therapy. Surviving animals were resistant to re-challenge with D2F2/E2 suggesting a memory immune response. Histopathologic analysis demonstrated a dense inflammatory infiltrate of tumor nodules within days of therapy and foamy histiocytes replacing the tumor nodules 2 weeks following therapy. These studies demonstrate that targeted rrVSV combined with anti-CTLA4 MAb can eliminate established macroscopic tumor implants by eliciting an anti-tumor CD4 and CD8 T-cell immunologic response.     

Treatment with allogeneic interleukin-2 secreting fibroblasts protects against the development of malignant brain tumors

We have reported that mice with an intracerebral (i.c.) malignant glioma or breast cancer treated with i.c. injection of allogeneic fibroblasts genetically engineered to secrete interleukin-2 (IL-2) survived longer than mice in various control groups. The goal of the present study was to determine the effectiveness of utilizing IL-2 secreting allogeneic fibroblasts as a protective treatment to prevent the development of an i.c. glioma or breast carcinoma. Using an intracranial microcannula system that we developed, the animals received weekly injections of the cellular vaccine prior to the introduction of tumor cells via the cannula. The results demonstrate a significant delay (P < 0.005) in the development of glioma in the animals pre-treated with either allogeneic non-secreting or IL-2-secreting fibroblasts prior to introduction of tumor cells. In addition, 50% of the animals pre-treated with IL-2 secreting allogeneic fibroblasts injected subsequently with G1261 glioma cells did not develop a tumor, while all of the animals injected with glioma cells alone and 92% of those treated with non-secreting fibroblasts eventually died. The long-term survivors from the pre-treatment group were subsequently re-challenged with tumor and compared to naive controls. There was evidence that long-term immunity was established in the pre-treated animals, since there was a significant prolongation of survival (P < 0.01). In similar experiments using breast cancer cells, 62% of the animals pre-treated with non-secreting allogeneic fibroblasts and 75% of the animals pre-treated with allogeneic IL-2 secreting fibroblasts subsequently injected with SB-5b breast carcinoma cells did not develop tumors and had a significant prolongation of survival. These data suggest that i.c. injection of allogeneic IL-2 secreting fibroblasts are effective as a protective treatment in the prevention of the development of a brain tumor when the fibroblasts are introduced into the same site where the tumor is subsequently injected.     

Paracrine immunotherapy with interleukin-2 and local chemotherapy is synergistic in the treatment of experimental brain tumors

Potent immune responses against malignant brain tumors can be elicited by paracrine intracranial (i.c.) immunotherapy with interleukin (IL)-2. Additionally, i.c. delivery of carmustine via biodegradable polymers has been shown to significantly prolong survival in both animal models and clinical trials. In this study, we show that the combination of paracrine immunotherapy, with nonreplicating genetically engineered tumor cells that produce IL-2, and local delivery of chemotherapy by biodegradable polymers prolongs survival in a synergistic manner in mice challenged intracranially with a lethal murine brain tumor. Animals receiving IL-2-transduced cells and polymers containing 10% 1,3-bis(2-chloroethyl)-1-nitrosourea had significantly improved survival compared with animals receiving IL-2-transduced cells or 10% 1,3-bis(2-chloroethyl)-1-nitrosourea alone. Median survival for the control group was 19 days. Survival in animals receiving IL-2-transduced cells and 1% carboplatin-containing polymers was also significantly improved compared with either therapy alone. Histopathological examination on day 14 of animals receiving combination treatment showed rare degenerating tumor cells. In addition to tissue necrosis surrounding the polymer, a marked inflammatory reaction was observed. In long-term survivors (all animals receiving combination treatment), no tumor was observed and the inflammatory reaction was completely resolved. The brains of animals receiving combination therapy showed both tissue necrosis due to local chemotherapy and strong inflammation due to paracrine immunotherapy. The demonstration of synergy between paracrine IL-2 and local i.c. delivery of antineoplastic drugs is novel and may provide a combined treatment strategy for use against both primary and metastatic i.c. tumors.     

Secretion of interleukin-10 from murine colon carcinoma cells suppresses systemic antitumor immunity and impairs protective immunity induced against the tumors

Interleukin-10 (IL-10) is a T helper type 2 (Th2) cytokine that suppresses Th1-mediated, cell-mediated immune responses and reciprocally enhances antibody-mediated responses. Previous studies, however, demonstrated that forced expression of the IL-10 gene in tumor cells could unexpectedly produce antitumor effects. We then examined whether tumor-derived IL-10 could modulate systemic immune responses. Murine colon carcinoma (Colon 26) cells that were retrovirally transduced with the murine IL-10 gene (Colon 26/IL-10) were inoculated in syngeneic immunocompetent or T cell-defective nude mice. Growth of Colon 26/IL-10 tumors was augmented in immunocompetent and, to less extent, in nude mice compared with that of wild-type tumors developed in respective mice. Growth of wild-type tumors was accelerated to the same level as that of Colon 26/IL-10 tumors when wild type and Colon 26/IL-10 cells were respectively inoculated in different flanks of the same immunocompetent mice. This enhanced growth of wild-type tumors was not observed in nude mice. Immunocompetent mice that had rejected IL-2- or IL-12-secreting Colon 26 cells developed protective immunity and became completely resistant to wild-type Colon 26 cells subsequently challenged. However, some of the mice that had rejected IL-2 or IL-12 producers developed Colon 26/IL-10 tumors inoculated thereafter. The present study showed that production of IL-10 from tumor cells impaired T cell- and non-T cell-mediated systemic antitumor immunity in hosts.     

Adoptive immunotherapy using lymphokine-activated killer (LAK) cells and interleukin-2 for recurrent malignant primary brain tumors

Summary Ten patients with recurrent malignant primary brain neoplasms were treated with adoptive immunotherapy using lymphokine-activated killer (LAK) cells and interleukin-2 (IL-2). Nine patients had supratentorial glioma and they received multiple intratumoral instillations of LAK cells through reservoir-catheter system or burrhole. The other patients with disseminated subarachnoid metastases from posterior fossa medulloblastoma received immunotherapy via lumbar subarachnoid route. A partial and transient clinical response was observed in two patients following the therapy, and a cystic transformation of the essentially solid tumor was noted on the CT scans of these two patients. No significant clinical or radiological response to the treatment was observed in the remaining 8 patients. The results of this preliminary study reveal limitations of the regional intratumoral adoptive immunotherapy using currently available techniques and provide sufficient evidence of its effectiveness to warrant further investigations.     

Immunotherapy targeting HER2 with genetically modified T cells eliminates tumor-initiating cells in osteosarcoma

Despite radical surgery and multi-agent chemotherapy, less than one third of patients with recurrent or metastatic osteosarcoma (OS) survive. The limited efficacy of current therapeutic approaches to target tumor-initiating cells (TICs) may explain this dismal outcome. The purpose of this study was to assess the impact of modified T cells expressing a human epidermal growth factor receptor (HER2)-specific chimeric antigen receptor in the OS TIC compartment of human established cell lines. Using the sarcosphere formation assay, we found that OS TICs were resistant to increasing methotrexate concentrations. In contrast, HER2-specific T cells decreased markedly sarcosphere formation capacity and the ability to generate bone tumors in immunodeficient mice after orthotopic transplantation. In vivo, administration of HER2-specific T cells significantly reduced TICs in bulky tumors as judged by decreased sarcosphere forming efficiency in OS cells isolated from explanted tumors. We demonstrate that HER2-specific T cells target drug resistant TICs in established OS cell lines, suggesting that incorporating immunotherapy into current treatment strategies for OS has the potential to improve outcomes.