Humoral Antitumor Responses Research Articles

Tertiary lymphoid structures in tongue cancer: Association with clinicopathological parameters, preoperative S-1 chemotherapy response, and prognosis.

Tertiary lymphoid structures (TLSs) are observed in cancer-invasive sites of various organs, and show evidence of tumor-specific B and/or T cells, suggesting an active humoral antitumor response. The aim of this study was to evaluate the relationship between TLSs and prognosis in patients with tongue squamous cell carcinoma (TSCC) after preoperative S-1 chemotherapy. Among 196 TSCC cases, 111 patients who received preoperative S-1 chemotherapy were compared to 85 patients who did not receive chemotherapy. We investigated the incidence of TLSs in both preoperative biopsy and resected specimens. TLSs were present in 24 (12%) biopsy specimens and 31 (16%) resected specimens. TLSs were associated with clinicopathologically advanced cases and positivity for lymphatic invasion. None of the cases with pStage 0 (i.e., noninvasive cancer) showed TLSs. In preoperative S-1 chemotherapy cases, TLSs were significantly more common in those treated with S-1 for more than 21 days and in those with treatment effects 0, Ia, and Ib. TLSs may not be a favorable prognostic factor by themselves but maybe a prognostic factor when combined with preoperative S-1 treatment. The presence of TLSs was suggested to be a factor indicating a favorable prognosis when considering the indication for preoperative S-1 chemotherapy. The synergistic effect of S-1 by activating antitumor immunity may be associated with a better prognosis in TSCC patients with TLSs.

Rational Design of T-Cell- and B-Cell-Based Therapeutic Cancer Vaccines.

Cancer vaccines provide an efficient strategy to enhance tumor-specific immune responses by redeploying immune systems. Despite the approval of the first cancer vaccine (Sipuleucel-T) by the U.S. Food and Drug Administration in 2010, most therapeutic cancer vaccines fail in clinical trials. Basically, tumor-specific immune responses rely on not only T-cell but also B-cell immunity, which indicates that cancer vaccines should leverage both arms of the adaptive immune system. For example, CD8+ T cells activated by antigen-presenting cells (APCs) recognize and directly kill tumor cells via peptide-bound major histocompatibility complex (pMHC). B cells recognize antigen with no need of pMHC and require CD4+ T cells for sufficient activation and antibody generation, enabling antibody-mediated nondirect killing on tumor cells. Considering the different mechanisms of T-cell and B-cell activation, the rational design of therapeutic cancer vaccines should consider several factors, including antigen selection and recognition, immune activation, vaccine delivery, and repeatable vaccination, which can be advanced by chemical strategies.In this Account, we summarize our recent contributions to the development of effective T-cell- and B-cell-based therapeutic cancer vaccines. For T-cell-based vaccines, we focus on adjuvants as the key component for controllable APC activation and T-cell priming. Not only synthetic molecular agonists of pattern recognition receptors (PRRs) but also adjuvant nanomaterials were explored to satisfy diversiform vaccine designs. For example, a type of natural cyclic dinucleotide (CDN) that was chemically modified with fluorination and ipsilateral phosphorothioation to activate the stimulator of interferon gene (STING) was found to mediate antitumor responses. It retains structural similarity to the parent CDN scaffold but possesses increased stability, cellular uptake, and immune activation for antitumor treatment. It also facilitates facile conjugation with other agonists, which not only enhances APC-targeting delivery but also balances cellular and humoral antitumor responses. We also explored the intrinsic properties of nanomaterials that allow them to serve as adjuvants. A black phosphorus nanosheet-based nanovaccine was constructed and found to strongly potentiate antigen-specific T-cell antitumor immune responses through multiple immune-potentiating properties, leading to a highly integrated nanomaterial-based adjuvant design. For B-cell-based vaccines, multicomponent and multivalent strategies were applied to improve the immunogenicity. A multicomponent linear vaccine conjugate coordinates helper T (Th) cells and APCs to proliferate and differentiates B cells for enhanced antitumor immunoglobulin G antibody responses. To further improve antigen recognition, clustered designs on a multivalent epitope were applied by generating various structures, including branched lysine-based peptides, natural multivalent scaffold molecules, and self-assembled nanofibers. We also engineered nano- and microvaccine systems to optimize systemic and localized vaccination. A multilayer-assembled nanovaccine successfully integrated antigens and multiple agonists to modulate APC activation. A DNA hydrogel contributed to the control of APC's immune behaviors, including cell recruitment, activation, and migration, and induced robust antitumor responses as an all-in-one designable platform. In this Account, by summarizing strategies for both T-cell- and B-cell-based vaccine design, we not only compare the differences but also address the intrinsic uniformity between such vaccine designs and further discuss the potential of a combined T-cell- and B-cell-based vaccine, which highlights the applicability and feasibility of chemical strategies.

Engineered porous/hollow Burkholderia pseudomallei loading tumor lysate as a vaccine

Due to its size, shape, and inherent expression of pathogen-associated molecular patterns and invasion-assistant adhesion proteins, Burkholderia pseudomallei can easily attach to, and then be internalized by, dendritic cells (DCs), leading to more efficient antigen cross-presentation if modified as carrier. Herein, we engineered Burkholderia pseudomallei as a porous/hollow carrier (SB) for loading tumor lysates (L) and adjuvant CpG (C) to be used as a tumor vaccine (SB-LC). We found that the adhesion proteins of Burkholderia pseudomallei promote internalization of the SB-LC vaccine by DCs, and result in enhanced DC maturation and antigen cross-presentation. SB-LC induces robust cellular and humoral antitumor responses that synergistically inhibit tumor growth with minimal adverse side effects in several tumor models. Moreover, SB-LC vaccination reverses the immunosuppressive tumor microenvironment, apparently as a result of CD8+-induced tumor ferroptosis. Thus, SB-LC is a potential model tumor vaccine for translating into a clinically viable treatment option.

Immunization with a Synthetic Human MUC1 Glycopeptide Vaccine against Tumor-Associated MUC1 Breaks Tolerance in Human MUC1 Transgenic Mice.

Breaking tolerance is crucial for effective tumor immunotherapy. We showed that vaccines containing tumor-associated human MUC1 glycopeptides induce strong humoral antitumor responses in mice. The question remained whether such vaccines work in humans, in systems where huMUC1 is a self-antigen. To clarify the question, mice transgenic in expressing huMUC1, mimicking the self-tolerant environment, and wild-type mice were vaccinated with a synthetic vaccine. This vaccine comprised STn and Tn antigens bound to a MUC1 tandem repeat peptide coupled to tetanus toxoid. The vaccine induced strong immune responses in wild-type and huMUC1-transgenic mice without auto-aggressive side effects. All antisera exhibited almost equivalent binding to human breast tumor cells. Similar increases of activated B-, CD4+ T-, and dendritic cells was found in the lymph nodes. The results demonstrate that tumor-associated huMUC1 glycopeptides coupled to tetanus toxoid are promising antitumor vaccines.

Potent CD4+ T cell-associated antitumor memory responses induced by trifunctional bispecific antibodies in combination with immune checkpoint inhibition.

Combinatorial approaches of immunotherapy hold great promise for the treatment of malignant disease. Here, we examined the potential of combining an immune checkpoint inhibitor and trifunctional bispecific antibodies (trAbs) in a preclinical melanoma mouse model using surrogate antibodies of Ipilimumab and Catumaxomab, both of which have already been approved for clinical use. The specific binding arms of trAbs redirect T cells to tumor cells and trigger direct cytotoxicity, while the Fc region activates accessory cells eventually giving rise to a long-lasting immunologic memory. We show here that T cells redirected to tumor cells by trAbs strongly upregulate CTLA-4 expression in vitro and in vivo. This suggested that blocking of CTLA-4 in combination with trAb treatment enhances T-cell activation in a tumor-selective manner. However, when mice were challenged with melanoma cells and subsequently treated with antibodies, there was only a moderate beneficial effect of the combinatorial approach in vivo with regard to direct tumor destruction in comparison to trAb therapy alone. By contrast, a significantly improved vaccination effect was obtained by CTLA-4 blocking during trAb-dependent immunization. This resulted in enhanced rejection of melanoma cells given after pre-immunization. The improved immunologic memory induced by the combinatorial approach correlated with an increased humoral antitumor response as measured in the sera and an expansion of CD4+ memory T cells found in the spleens.

Novel vaccines for glioblastoma: clinical update and perspective.

Glioblastoma is the most common primary brain cancer. Aggressive treatment with surgery, radiation therapy and chemotherapy provides limited overall survival benefit. Glioblastomas have a formidable tumor microenvironment that is hostile to immunological effector cells and these cancers produce profound systemic immunosuppression. However, surgical resection of these tumors creates conditions that favor the use of immunotherapeutic strategies. Therefore, extensive surgical resection, when feasible, will remain part of the equation to provide an environment in which active specific immunotherapy has the greatest chance of working. Toward that end, a number of vaccination protocols are under investigation. Vaccines studied to date have produced cellular and humoral antitumor responses, but unequivocal clinical efficacy has yet to be demonstrated. In addition, focus is shifting toward the prospect of therapies involving vaccines in combination with immune checkpoint inhibitors and other immunomodulatory agents so that effector cells remain active against their targets systemically and within the tumor microenvironment.

Association of humoral antitumor response with clinical benefit in catumaxomab-treated malignant ascites patients: Results from a phase IIIb study.

2584 Background: The bispecific antibody catumaxomab (anti-EpCAM x anti-CD3) which is approved for the treatment of malignant ascites (MA) patients (pts) in the EU elicits a humoral immune response against tumor-associated antigens. Here we present follow up data analyzing the influence of this antibody response on puncture free (PFS) and overall survival (OS). Methods: In the course of the phase IIIb study CASIMAS, MA pts with EpCAM positive tumors were treated with/without prednisolone premedication by 4 infusions of 10, 20, 50 and 150 µg of catumaxomab over 11 days (d). EpCAM and HER2-specific antibody responses in plasma samples of 23 pts were measured by ELISA. Additionally, samples of 5 pts receiving a second treatment cycle were analyzed. Pts with significant increase (≥ 2) or de novo development of anti-tumor antibodies within 38 d after treatment start were defined as responders (R). Non responders (NR) showed no humoral response by d 38 or died before. PFS and OS of R and NR were compared by Kaplan Meier analysis. Results: 11 of 23 pts (48%) showed an anti-EpCAM response and 14 of 23 pts (61%) developed HER2-specific antibodies. 6 pts (26%) reacted positive against both antigens, 4 pts (17%) had neither response. In contrast to the EpCAM R group where 73% of pts displayed detectable antibodies prior to therapy, antibodies against HER2 developed de novo. Of note, 4 of 5 individuals who received a second treatment cycle after recurring MA demonstrated an anti-HER2 Ig booster reaction which was stronger and faster in comparison to pts who received only one treatment cycle (median values at d 18: 65 vs. 11 ng/ml). Most important, there was an almost 6 fold increase in median PFS between the HER2 R and NR group (68 vs 12 d, p = 0.044 (log-rank). There was also a trend towards improved OS for pts showing either anti-HER2 and/or anti-EpCAM responses (n=19) in comparison to pts with no response at all (n=4; 143 vs. 67 d, median, p = 0.054). Conclusions: The results indicate that active anti-tumor immunization triggered by catumaxomab treatment in MA pts is associated with improved clinical outcome. Further investigations of these vaccine-like effects with higher pts numbers are warranted.

A novel autologous oxidized whole-tumor antigen vaccine therapy for recurrent ovarian cancer.

5023 Background: Despite surgical and chemotherapeutic advances, the death rate from ovarian cancer has not changed. We report here an enhanced dendritic cell vaccine platform developed for clinical testing. Furthermore we report the application of this novel platform comprising of dendritic cell (DC)-based autologous whole tumor antigen vaccination in a pilot study of patients with recurrent ovarian cancer. Methods: To determine the optimal tumor lysate preparation for loading DCs, ovarian tumor lines were prepared by HOCl-oxidation, UVB-irradiation or freeze and thaw. Normal donor DCs were evaluated for tumor lysate uptake, cytokine and chemokine productions and phenotype. The optimal lysate preparation, was used in a phase I study where five patients with recurrent ovarian cancer with available tumor lysate from secondary debulking surgery underwent intranodal vaccination with OC-DC, an autologous DC preparation pulsed with HOCL oxidized autologous tumor cells. Feasibility, safety, and biological and clinical efficacy were evaluated. Results: Normal donor DCs pulsed with HOCl-oxidized tumor lines demonstrated the highest tumor lysate uptake, matured efficiently after LPS and IFN-gamma stimulation, and produced higher levels of proinflammatory cytokines and chemokines. In vitro, these lysates loaded DCs primed T cell responses against ovarian tumor associated antigens and effectively expanded against tumor specific T cells from donors and patients. Therapy was feasible and well tolerated in all subjects. Vaccination with OC-DC produced limited grade 1 toxicities and elicited tumor-specific T cell responses. Moreover specific HLA-A2-restricted responses were documented following vaccination and HER-2/neu specific T cells were expanded following 10 days of in vitro culture. Patients exhibiting immune response demonstrated clinical benefit including two patients who demonstrated remission inversion on vaccine maintenance. Conclusions: We developed a DC-HOCl oxidized whole tumor lysate vaccine which was safe and well-tolerated by patients. The vaccine was highly proinflammatory and elicited cellular and humoral anti-tumor responses establishing a platform for immune-combinatorial therapy.

Abstract LB-133: Vaccination with dendritic cells pulsed with autologous oxidized whole tumor lysate induced strong and long-lasting anti-tumor immunity in recurrent ovarian cancer patients

Abstract Background Despite surgical and chemotherapeutic advances, the death rate from ovarian cancer has not changed over the past two decades. We report here an enhanced, more rapid and more immunogenic dendritic cell vaccine platform developed for clinical testing. Furthermore we report the application of this novel immunotherapy platform comprising of dendritic cell (DC)-based autologous whole tumor antigen vaccination in a pilot study of patients with recurrent ovarian cancer. Methods To determine the optimal tumor lysate preparation for loading DCs, ovarian tumor lines (SKOV3, OVCAR5 and A1847) were prepared by HOCl-oxidation, UVB-irradiation or freeze and thaw. Normal donor DCs were evaluated for tumor lysate uptake, cytokine and chemokine productions and phenotype after maturation with lipopolysaccharides (LPS) and interferon (IFN)-gamma. The optimal lysate preparation, was used in a phase I study where five patients with recurrent, progressive stage III and IV ovarian cancer with available tumor lysate from secondary debulking surgery underwent intranodal vaccination with OC-DC, an autologous DC preparation pulsed with HOCl-oxidized autologous tumor cells (5-10 x 106 DC per dose, 5 doses). Feasibility, safety, and biological and clinical efficacy were evaluated. Results Normal donor DCs pulsed with HOCl-oxidized tumor lines demonstrated the highest tumor lysate uptake, matured efficiently after LPS and IFN-gamma stimulation, and produced higher levels of proinflammatory cytokines and chemokines including IL-1, IL-6, IL-8, IL-12, IP-10, MIP-1alpha and MIG. In vitro, these lysates loaded DCs primed T cell responses against ovarian tumor associated antigens and effectively expanded against tumor specific T cells from donors and patients. Therapy was feasible and well tolerated in all five subjects. Vaccination with OC-DC produced limited grade 1 toxicities and elicited tumor-specific T cell responses. Moreover specific HLA-A2-restricted responses to HER-2/neu, MUC1, NYESO-1, mesothelin and WT1 were documented following vaccination and HER-2/neu specific T cells were expanded following 10 days of in vitro culture. Patients exhibiting immune response demonstrated clinical benefit including two patients who demonstrated remission inversion on vaccine maintenance. Conclusions We developed a DC-HOCl oxidized whole tumor lysate vaccine which was safe and well-tolerated by all patients. The DC vaccine was highly proinflammatory and elicited cellular and humoral anti-tumor responses establishing a platform for immune-combinatorial therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-133. doi:1538-7445.AM2012-LB-133

Transfer of Cellular and Humoral Anti-Tumor Immunity with Immune T Cells After Stem Cell Transplant (SCT) for Metastatic Breast Cancer Following “Vaccination” with Anti-CD3 x Anti-Her2/Neu Bispecific Antibody (Her2Bi) Armed Activated T Cells

Abstract 1914Novel therapeutic approaches are needed for women with metastatic breast cancer (BrCa). In our phase I clinical trial, infusions of anti-CD3 activated T cells (ATC) armed with anti-CD3 x anti-Her2/neu bispecific antibody (Her2Bi) induced specific cytotoxicity (SC) directed at SK-BR-3 breast cancer cells by fresh peripheral blood lymphocytes (PBL) and induced elevated serum levels of Th1 cytokines. In this study, we took advantage of armed ATC induced anti-tumor immune responses by infusing “immune” T cells collected by leukopheresis. We expanded “immune T cells” with anti-CD3 and IL-2, followed by a cryopreservation for multiple re-infusions of ATC after high dose chemotherapy (HDC) and autologous stem cell transplant (SCT). We asked whether this approach would transfer anti-tumor responses back into patients after HDC and SCT to accelerate the development of cellular and humoral anti-tumor responses. This strategy of “prime” with armed ATC and “boost” with ATC was performed in 5 evaluable patients. The “priming” portion involved 8 infusions of (2 infusions/week for 4 weeks) armed ATC given with daily low dose IL-2 (300,000 IU/m2/day) and twice weekly GM-CSF (250 μg/m2). Approximately 3 weeks after the armed ATC infusions, patients underwent a second leukopheresis for the collection and expansion of ATC. The expanded ATC from 6 patients at an effector:target ratio (E/T) of 25:1 exhibited specific cytotoxicity (SC) ranging from 3.7–25.8 (mean = 13.6%) directed at the SK-BR-3. Phenotyping of the ATC showed a mean of 50.2 % (25–74) CD4+ cells, 30.4 % (16.3-51.3) CD8+ cells, 11.6% (4.5-24.3) CD56+CD16+ cells, and 29.5% (10.4–41) CD4+CD25+ cells. A separate leukopheresis after G-CSF stimulation was performed to obtain CD34+ cells for the SCT. After HDC and PBSCT, 5 evaluable patients received multiple infusions with a mean total of 54×109 ATC (16–110 × 109) beginning day +1 after SCT. No G-CSF was given to accelerate engraftment. There were no dose-limiting side effects or delays in engraftment. One patient developed sepsis, multiple organ failure and recovered fully with supportive care and antibiotics. Phenotyping at 2 weeks after SCT showed the mean proportions of CD4+ and CD8+ cells to be 55.5 and 17.7%, respectively. Specific cytotoxicity (SC) directed at SK-BR-3 targets ranged from 4.7 to 70% at E/T of 25:1 up to 18 months post SCT but not against a negative control cell line-Daudi. Mean serum anti-SK-BR-3 antibody levels were 800 ng/ml preSCT and 1500, 1080 and 1360 ng/ml at 1, 2, and 3 months post SCT, respectively. In vitro anti-SK-BR-3 antibody synthesis was assessed using a new assay (Thakur et al, Cancer Immunol Immunother EPub, 2011) showed easily detectable levels of in vitro anti-SK-BR-3 antibody synthesis. The mean anti-SK-BR-3 antibody synthesis in the presence of CpG in pre-immunotherapy (Pre-IT), mid-IT, 1 months post-IT, pre-SCT and 1, 2, and 3 months post-SCT is summarized in the table. PBL produced anti-SK-BR-3 antibody pre-SCT and there was clear recovery of anti-SK-BR-3 antibody synthesis by PBL at 2 and 3 months after SCT. These data show infusions of immune ATC transferred cytotoxic T lymphocytes and humoral antibody activity directed at tumor antigens. These novel findings suggest that adaptive immunity was transferred into patients by ATC infusions and the stem cell product after myeloablation and SCT leading to rapid reconstitution of anti-tumor immunity.Time PointsCulture ConditionsMean±SD (n=3)Pre-ITCpG23±27Mid-ITCpG66±671M Post-ITCpG41±67Pre-SCTCpG92±101M Post-SCTCpG9±182M Post-SCTCpG45±273M Post-SCTCpG82±55 Disclosures:Lum:Transtarget Inc: Equity Ownership, Founder of Transtarget.

Induction of Specific Cellular and Humoral Responses Against Renal Cell Carcinoma After Combination Therapy With Cryoablation and Granulocyte-Macrophage Colony Stimulating Factor

Cryotherapy offers a minimally invasive treatment option for the management of both irresectable and localized prostate, liver, pulmonary, and renal tumors. The antineoplastic effects of cryotherapy are mediated by direct tumor lysis and by indirect effects, such as intracellular dehydration, pH changes, and microvascular damage resulting in ischemic necrosis. In this study, we investigated whether percutaneous cryoablation of lung metastasis from renal cell carcinoma (RCC) in combination with aerosolized granulocyte-macrophage colony stimulating factor can induce systemic cellular and humoral immune responses in 6 patients with RCC. Peripheral blood mononuclear cells (PBMCs) were sequentially studied up to 63 days post cryoimmunotherapy (CI). PBMC from pre and post CI were phenotyped for lymphocyte subsets and tested for cytotoxicity and interferon-γ EliSpots directed at RCC cells. Humoral responses were measured by in vitro antibody synthesis assay directed at RCC cells. The immune monitoring data showed that CI induced tumor specific cytotoxic T lymphocyte, specific in vitro antitumor antibody responses, and enhanced Th1 cytokine production in 4 of 6 patients. More importantly, the magnitude of cellular and humoral antitumor response seems to be associated with clinical responses. These pilot data show that CI can induce robust and brisk cellular and humoral immune responses in patients with metastatic RCC, but requires further evaluation in optimized protocols.

Characterization of humoral responses of ovarian cancer patients: Antibody subclasses and antigenic components

Objectives Current antigen-based diagnostic assays for ovarian cancers rely on intravasation of specific aberrantly expressed proteins and their achieving detectable steady-state concentrations, resulting in their inability to truly detect small early lesions. In contrast, tumor antigen immunorecognition is observed following initial transformation events. Our objective was to characterize humoral antitumor responses in terms of IgG subclasses generated and tumor antigens recognized. Methods For patients with benign and malignant ovarian disease, tumor-reactive IgG subclasses were characterized by Western immunoblotting. Antigen recognition patterns were analyzed by 2-dimensional electrophoresis and proteins exhibiting shared or stage-specific recognition were defined by mass spectrometry (MS) sequencing. Results Sera from ovarian cancer patients exhibited significantly greater immunoreactivities than either controls or women with benign disease. While late-stage patients recognized more proteins at greater intensity, stage-specific differential recognition patterns were observed in the IgG subclasses, with the greatest recognition appearing in IgG2 subclasses. Immunoreactivity in IgG2 and IgG3 from stage I and II patients appears to be most intense with nuclear antigens > 40 kDa, while, in stage III patients, additional immunoreactivity was present in the < 40 kDa components. Stage III patients also exhibited similar reaction with membrane antigens < 40 kDa. Two-dimensional electrophoresis revealed 32 stage-linked antigenic differences with 11 in early-stage and 21 in late-stage ovarian cancer. Conclusions Owing to the timing and stability of humoral responses, quantitation of IgG subclasses recognizing specific tumor antigens provides superior biomarkers for early cancer identification and allows for differentiation of benign versus malignant ovarian masses and early- and late-stage cancers.

Interleukin-21 Augments the Efficacy of T-Cell Therapy by Eliciting Concurrent Cellular and Humoral Responses

Interleukin (IL)-21 modulates T-cell-associated, B-cell-associated, and natural killer cell-associated immunity. However, the potential of IL-21 to simultaneously stimulate cellular and humoral antitumor responses and the mechanisms involved have not yet been adequately explored. In this report, we examined the immune-modulating effect of IL-21 when used in vitro and its adjuvant effects when administrated concomitantly with T-cell transfer for cancer therapy. Use of IL-21 in concert with IL-2 in culture up-regulated both type 1 and type 2 cytokine production of activated tumor-draining lymph node cells and enhanced their therapeutic efficacy. Administration of IL-21 and IL-2 as an adjuvant to T-cell transfer resulted in simultaneously elicited cellular and humoral responses. This concurrent response has led to effective regression of established pulmonary metastatic tumors and s.c. tumors. T-cell transfer plus IL-21/IL-2 administration conferred systemic immunity to the treated hosts. This was evident by the induction of protective immunity against tumor rechallenge, expansion of memory T cells, and significantly elevated serum levels of IFN gamma and IL-10. Furthermore, we observed significantly enhanced tumor-associated antibody response after T-cell + IL-2 + IL-21 therapy. Cytotoxic antibody subclass IgG2b increased strikingly in the sera of treated animals; they bound specifically to MCA205 tumor cells, and such immune sera mediated tumor cell lysis in the presence of complement. Use of B-cell-deficient mice provided direct evidence that humoral responses contribute to T-cell + IL-2 + IL-21-elicited antitumor immunity. Collectively, these findings provide a rationale to evaluate the use of IL-21 in T-cell therapy of human cancers.

Delayed tumor onset and reduced tumor growth progression after immunization with a Her-2/neu multi-peptide vaccine and IL-12 in c-neu transgenic mice

Passive immunotherapy with monoclonal antibodies is a routinely performed but cost intensive treatment against certain cancers. Induction of humoral anti-tumor responses by active peptide immunization has therefore become a favorable treatment concept. We have recently identified three peptides representing B-cell epitopes of the extracellular domain of Her-2/neu each of them inducing Her-2/neu specific immune responses with anti-tumor activity in vitro. The present study was performed to evaluate the in vivo protective capacity of a combined vaccination with these three peptides in FVB/N transgenic mice spontaneously developing c-neu overexpressing breast cancers. The three Her-2/neu peptides coupled to tetanus toxoid were administered with or without addition of recombinant IL-12. At the time all untreated mice had developed tumors about 40% of peptide-immunized mice and nearly 60% of mice immunized with the peptide vaccine co-applied with IL-12 remained tumor free. Moreover, co-administration of IL-12 had a significant impact on the retardation of tumor progression. The enhanced anti-tumor efficacy of the vaccine by IL-12 was associated with a Th1 biased immune response as demonstrated by an increased IFN-gamma production in vitro and elevated Her-2-specific IgG levels. Our findings clearly demonstrate that this multi-peptide vaccine is effective in tumor prevention and support its use against minimal disease, drug-resistant tumors or even for prophylaxis against cancers overexpressing Her-2/neu.

GM-CSF-secreting melanoma vaccines.

The development of biochemical and genetic schemes to characterize cancer antigens led to the recognition that malignant melanoma frequently evokes a host response. While the generation of brisk T-cell infiltrates in early stage disease is correlated with prolonged survival, host reactions in most cases are insufficient to impede tumor progression. One variable that may limit the potency of the host response against nascent melanoma is the mixture of cytokines present in the tumor microenvironment. In a murine melanoma model, we identified granulocyte-macrophage colony stimulating factor (GM-CSF) as the most potent molecule for augmenting tumor immunity following gene transfer into melanoma cells. Vaccination with irradiated melanoma cells engineered to secrete GM-CSF enhances host responses through improved tumor antigen presentation by recruited dendritic cells and macrophages. Melanoma-specific CD4(+) and CD8(+) T-cells, CD1d-restricted NKT-cells, and antibodies mediate tumor rejection. Initial testing of this immunization strategy in patients with metastatic melanoma revealed the consistent induction of cellular and humoral antitumor responses that provoked the extensive necrosis of distant metastases without significant toxicity.

GM-CSF-based cancer vaccines.

The crafting of genetic and biochemical techniques to identify cancer antigens yielded the unexpected discovery that immune recognition of tumors regularly accompanies cancer development. The failure of the host to suppress tumor formation or attenuate disease progression may thus reflect the limited immunogenicity of nascent tumors. One critical determinant of host immunity is the mixture of cytokines produced in the tumor microenvironment. We have compared a large number of secreted and surface molecules for their relative abilities to augment tumor immunity following gene transfer into cancer cells. In multiple murine models, granulocyte-macrophage colony stimulating factor (GM-CSF) proved to be the most potent immunostimulatory product. Vaccination with irradiated tumor cells engineered to secrete GM-CSF involves enhanced tumor antigen presentation by recruited dendritic cells (DCs) and macrophages; the coordinated functions of CD4+ and CD8+ T cells, CD1d-restricted NKT cells and antibodies mediate protective immunity. The evaluation of this vaccination strategy in patients with advanced melanoma revealed the consistent induction of cellular and humoral antitumor responses capable of effectuating substantial necrosis of distant metastases. The formulation of simplified methods for manufacturing autologous, GM-CSF-secreting tumor cells has enabled more extensive clinical testing in diverse patient settings.

Vaccine therapies for non-Hodgkin's lymphoma.

Various clinical observations suggest that non-Hodgkin's lymphomas (NHLs), particularly those of low histologic grade, can be controlled by immunologic mechanisms. Although many effective therapies exist for the initial treatment of low grade lymphomas, none are curative and most have significant toxic side effects. Several promising lymphoma tumor antigen vaccines are being studied at medical centers throughout North America. I favor the scientific evaluation of a therapeutic strategy for follicular NHL that places immune-based therapies forward in the treatment algorithm to the initial therapeutic decision point. Active immunotherapies (therapeutic tumor vaccines) are instituted in tandem with initial cytoreductive chemotherapy, and followed by passive monoclonal antibody therapies. The tumor-specific idiotype vaccines are favored because of their demonstrated potential for clinical activity in numerous human studies and their lack of significant toxic side effects. Rituximab and other monoclonal antibodies directed at normal B-cell antigens are known to abrogate the host's ability to mount primary humoral immune responses, including antitumor antibodies evoked by tumor vaccines. Therefore, one should consider deferring the use of these agents until after an attempt at generating a host humoral antitumor response using investigational tumor vaccines. Chemotherapy regimens containing highly immunosuppressive agents (ie, fludarabine) or organ dose-limiting toxicities (ie, doxorubicin) may be best reserved for later in the disease course for those failing the more conservative approaches and for cases with adverse prognostic features. This strategy may give patients the greatest chance at prolonged remission or cure while minimizing acute and chronic toxicities, although its impact on overall survival has not been proven. Low grade NHLs remain the proving ground for this treatment philosophy. Hopefully, in the future, similar strategies may be applicable to NHLs of other grades and histologies.

The humoral antitumor responses induced by IL-4 gene-modified tumor vaccine

It is well known that IL-4 plays important roles in the induction of humoral immunity. In the present study, the humoral antitumor responses induced by IL-4 gene-modified tumor vaccine were investigated. The mice were vaccinated with the IL-4 gene-modified B16 melanoma cells. Then the proliferative capacity of the splenic lymphocytes, the levels of the antibodies in the murine serum against wild-type B16 cells and the cytotoxicity of the serum to wild-type melanoma cells were detected. Our data showed that the LPS-induced proliferation of the splenic lymphocytes from the mice vaccinated with the IL-4 gene-modified tumor vaccine increased more significantly than that from mice vaccinated with wild-type tumor vaccine. The cytotoxicity of the serum to wild-type melanoma cells also increased markedly when detected. It was also observed that the number of pulmonary metastases decreased more obviously when the mice were intravenously injected with the mixture of wild-type B16 cells and the serum from the mice vaccinated with the IL-4 gene-modified B16 cells. Our data demonstrated that humoral immunity might contribute to the antitumor effect of IL-4 gene therapy.

Spontaneous regression of acquired immune deficiency syndrome-related, high-grade, extranodal non-Hodgkin's lymphoma

Spontaneous regression of low-grade non-Hodgkin's lymphoma often has been reported. Proposed mechanisms of this event have included concomitant infections and enhanced cellular and humoral antitumor responses by the host. Spontaneous regression of high-grade non-Hodgkin's lymphoma is rare and has never been reported in a patient with acquired immune deficiency syndrome (AIDS). The authors report a patient with spontaneous regression of AIDS-related non-Hodgkin's lymphoma and discuss the role of host immunity in mediating spontaneous regression.