Tumor-derived Heat Shock Proteins Research Articles

Identifying Antigen Presenting Cells Responsible for Heat Shock Protein-Mediated Cancer Immunosurveillance

Abstract The immune system detects and eliminates nascent, emerging tumor cells. This is mediated primarily by T cells and NK cells. However, the mechanisms that allow efficient T cell priming during cancer immunosurveillance, which is characterized by limited antigen availability, remain unclear. Immunogenic heat shock proteins (HSPs) such as gp96 chaperones minute levels of antigens, in the form of peptides, and allows these to be efficiently cross-presented by APCs, a process that involves the HSP receptor, CD91. Further, engagement of CD91 by HSPs initiates signals for co-stimulation and cytokine production which are necessary for priming anti-tumor responses. We previously showed that mice deficient in CD91 expression in APCs (CD91fl/flCD11cCre) are more susceptible to chemically induced tumors compared to wildtype littermates. Tumors that emerge in these mice prime poorer T cell responses and are less infiltrated than tumors in wildtype mice. The CD91+ APC subset(s) that are responsible for HSP-mediated T cell priming have not been elucidated. This study seeks to define the APC subset(s) necessary for CD91-mediated immune responses in the tumor microenvironment and tumor-draining lymph nodes. Using genetically tagged HSPs, we track the dispersal of tumor-derived HSPs throughout the myeloid system. We show that HSPs are taken up by multiple DC and macrophage subsets. We identify APC subsets that are responsible for HSP-mediated priming of anti-tumor T cell responses, by adoptive transfer of APCs that acquire tumor-derived HSPs. These studies provide an underlying mechanism of how the immune responses to nascent tumors are initiated. They will also have significant implications for cancer prognosis and therapy. Supported by NIH (R01 CA233803)

Phase II trial of adjuvant immunotherapy with autologous tumor-derived Gp96 vaccination in patients with gastric cancer.

117 Background: Autologous, tumor-derived heat shock protein Gp96 peptides complexes have shown antitumor potential in various cancers. We conducted the first Phase II trial to evaluate the safety and efficacy of Gp96 vaccination in adjuvant settings for patients with gastric cancer. Methods: Consecutive patients from November 2012 to December 2015 were enrolled. Participants were allocated to the experimental group or control group, receiving Gp96 vaccination plus chemotherapy or chemotherapy alone respectively. The primary endpoints were disease-free survival and toxicity. The secondary outcomes were overall survival and tumor-specific immune responses. Results: Thirty-nine and forty patients received Gp96 vaccination plus chemotherapy and chemotherapy alone in the adjuvant settings respectively. Significant increased tumor-specific immune responses were observed after Gp96 vaccination. There were comparable disease-free survival ( p = 0.413; HR: 0.75; 95% CI: 0.37−1.48) and overall survival ( p = 0.485; HR: 0.68; 95% CI: 0.24−1.96) between experimental group and control group. In subgroup of patients with stage II and stage III gastric cancer, patients who have received Gp96 vaccination had improved disease-free survival compared those who have not ( p = 0.044; HR: 0.45; 95% CI: 0.22−0.96). Gp96 vaccination plus chemotherapy was well tolerated and no Gp96-related serious adverse event has been observed. Conclusions: Gp96 vaccination could elicit tumor-specific immune responses and could be safely used in adjuvant settings combined with chemotherapy. Patients with less aggressive diseases might benefit from Gp96 therapy.

Combinational Immunotherapy with Allo-DRibble Vaccines and Anti-OX40 Co-Stimulation Leads to Generation of Cross-Reactive Effector T Cells and Tumor Regression.

It is well-known that vaccines comprising of irradiated whole tumor cells or tumor-derived heat shock proteins can generate tumor-specific immune responses. In contrast, we showed recently that vaccines composed of autophagosomes (DRibbles) derived from syngeneic sarcomas could induce cross-reactive T-cell responses and cross-protection against the tumor. This unusual property of DRibbles was related to the selective recruitment of defective ribosomal products (DRiPs) and other short-lived proteins (SLiPs) into autophagosomes via sequestosome (SQSTM1, p62) mediated association of ubiquitinated SLiPs to the autophagy gene product LC3. Here, we extend our observations to mammary carcinomas from mice of different genetic background. We demonstrated that combined of intranodal administration of autologous or allogeneic DRibbles together with anti-OX40 antibody led to robust proliferation, expansion, and differentiation of memory and effector T cells. We also showed that SLiPs is an excellent source of antigen for cross-priming of CD8+ T-cells that recognize shared tumor antigens in the context of host MHC class I molecules. Thus, our results provide a strong basis for novel clinical trials that combine allogeneic “off-the-shelf” DRibble vaccines together with antibodies against co-stimulatory molecules.

Phenotypically distinct helper NK cells are required for gp96-mediated anti-tumor immunity.

A number of Heat Shock Proteins (HSPs), in the extracellular environment, are immunogenic. Following cross-presentation of HSP-chaperoned peptides by CD91+ antigen presenting cells (APCs), T cells are primed with specificity for the derivative antigen-bearing cell. Accordingly, tumor-derived HSPs are in clinical trials for cancer immunotherapy. We investigate the role of NK cells in gp96-mediated anti-tumor immune responses given their propensity to lyse tumor cells. We show that gp96-mediated rejection of tumors requires a unique and necessary helper role in NK cells. This helper role occurs during the effector phase of the anti-tumor immune response and is required for T cell and APC function. Gp96 activates NK cells indirectly via APCs to a phenotype distinct from NK cells activated by other mechanisms such as IL-2. While NK cells have both lytic and cytokine producing properties, we show that gp96 selectively activates cytokine production in NK cells, which is important in the HSP anti-tumor immune response, and leaves their cytotoxic capacity unchanged.

Abstract PR01: The heat shock protein-CD91 pathway is necessary for tumor immunosurveillance

Abstract Many tumors are capable of generating immune response in the bearing host. Since tumors lack the typical (foreign) PAMPs that provide signal 2 for T cell priming, the mechanism of how concomitant immunity is established remains a mystery. We provide evidence here that, heat shock proteins (HSPs), when released into the tumor microenvironment, is the immunogen necessary for tumor immunosurveillance. This response requires CD91- the endocytic and signaling receptor for the immunogenic HSPs. In our study, we generated CD11c-specific CD91 knockout mice and showed that transplantable tumors grew faster in those knockout mice, compared to wild type mice. In addition, we abrogated the interaction of tumor-derived HSP with CD91 in vivo by over-expression of Receptor Associated Protein (RAP), an endogenous inhibitor of CD91. The loss of CD91 funtion through antagonism or its deletion was shown to negatively affect cross-priming. While initial studies were performed on transplantable tumors, these experiments have now been carried out in chemically induced tumor models. In summary, our study demonstrates that the HSP-CD91 pathway is critical for establishment tumor immunity. Considering that elevated RAP levels have been reported in colon cancer patients, we propose a novel mechanism of immune evasion for tumors expressing competing ligands for immune receptors such as CD91. Citation Format: Yu Jerry Zhou, Robert J. Binder. The heat shock protein-CD91 pathway is necessary for tumor immunosurveillance. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr PR01.

Enhanced antitumor immunity of nanoliposome-encapsulated heat shock protein 70 peptide complex derived from dendritic tumor fusion cells.

Tumor-derived heat shock proteins peptide complex (HSP.PC-Tu) has been regarded as a promising antitumor agent. However, inadequate immunogenicity and low bioavailability limit the clinical uses of this agent. In a previous study, we first produced an improved HSP70.PC-based vaccine purified from dendritic cell (DC)-tumor fusion cells (HSP70. PC-Fc) which had increased immunogenicity due to enhanced antigenic tumor peptides compared to HSP70.PC-Tu. In order to increase the bioavailability of HSP70.PC-Fc, the peptide complex was encapsulated with nanoliposomes (NL-HSP70. PC-Fc) in this study. After encapsulation, the tumor immunogenicity was observed using various assays. It was demonstrated that the NL-HSP70.PC-Fc has acceptable stability. The in vivo antitumor immune response was increased with regard to T-cell activation, CTL response and tumor therapy efficiency compared to that of HSP70.PC-Fc. In addition, it was shown that DC maturation was improved by NL-HSP70.PC-Fc, which added to the antitumor immunity. The results obtained for NL-HSP70.PC-Fc, which improved immunogenicity and increases the bioavailability of HSP70.PC, may represent superior heat shock proteins (HSPs)-based tumor vaccines. Such vaccines deserve further investigation and may provide a preclinical rationale to translate findings into early phase trials for patients with breast tumors.

Establishment of tumor-associated immunity requires interaction of heat shock proteins with CD91.

Host antitumor adaptive immune responses are generated as a result of the body's immunosurveillance mechanisms. How the antitumor immune response is initially primed remains unclear, given that soluble tumor antigens generally are quantitatively insufficient for cross-priming and tumors generally lack the classical pathogen-associated molecular patterns to activate costimulation and initiate cross-priming. We explored the interaction of the tumor-derived heat shock proteins (HSP) with their common receptor (CD91) on antigen-presenting cells (APC) as a mechanism for host-priming of T-cell-mediated antitumor immunity. Using targeted genetic disruption of the interaction between HSPs and CD91, we demonstrated that specific ablation of CD91 in APCs prevented the establishment of antitumor immunity. The antitumor immunity was also inhibited when the transfer of tumor-derived HSPs to APCs was prevented using an endogenous inhibitor of CD91. Inhibition was manifested in a reduction of cross-presentation of tumor-derived antigenic peptides in the lymph nodes, providing a molecular basis for the observed immunity associated with tumor development. Our findings demonstrate that early in tumor development, the HSP-CD91 pathway is critical for the establishment of antitumor immunity.

Tumor immunotherapy based on tumor-derived heat shock proteins (Review)

Heat shock proteins (HSPs), the most important type of molecular chaperone, are expressed in all eukaryotic cells and have multiple functions, including the folding and unfolding of other proteins and peptides, the transport of proteins and peptides and the support of antigen presentation processes. Due to these important properties, the use of HSPs has been explored as a promising tumor immunotherapy strategy. It has been previously demonstrated that HSP peptide complex (HSP.PC) derived from tumors is the immunogenic entity that elicits powerful antitumor immune responses. Previous animal studies and phase III clinical trials have demonstrated the efficacy, safety and feasibility of HSP-based tumor vaccines. However, the limitations are also apparent and specific alternatives have been developed. The present review focused on the history of HSP-based immunotherapy, the mechanism of its immunogenicity and the previous efforts to promote the efficacy. The current review may be useful for antitumor studies based on the tumor-derived HSPs.

Inhibition of the Heat Shock Protein receptor CD91 abrogates concomitant anti-tumor immunity (P2035)

Abstract Immunosurveillance mechanisms of tumors depend on the host’s ability to efficiently cross-present tumor antigens. We provide evidence here that heat shock proteins (HSPs), when released into the tumor microenvironment, is the antigen carrier necessary for priming concomitant tumor specific immunity. These responses require CD91- the endocytic and signaling receptor for the immunogenic HSPs. In our study, we generated CD11c-specific CD91 knockout mice and showed that tumors grew faster in those mice, compared to CD91+/+ mice. In addition, we abrogated the interaction of tumor-derived HSP with CD91 in vivo by over-expression of Receptor Associated Protein (RAP), an endogenous CD91 antagonist. The data showed that: first, tumors expressing RAP grew with significantly faster kinetics than the non-RAP expressing counterparts in wild type mice, although this difference was non-existent in immunocompromised mice; second, RAP-expressing tumors, when used as an immunogen in tumor prophylaxis, were significantly less efficient in priming immune responses; third, in the presence of RAP, less amount of tumor-derived EGFP-labeled HSPs were taken up by APCs in draining lymph nodes. In summary, our study demonstrates that the HSP-CD91 pathway is critical for establishment of concomitant immunity. Considering that elevated RAP levels have been reported in cancer patients, we propose a novel mechanism of immune evasion for tumors expressing competing ligands for immune receptors such as CD91.

Abstract A55: Inhibition of the heat shock protein receptor CD91 abrogates concomitant antitumor immunity.

Abstract Most tumors are capable of generating immune response in the bearing host, a phenomenon described as concomitant immunity. Since tumors lack the typical (foreign) PAMPs that provide signal 2 for T cell priming, the mechanism of how concomitant immunity is established remains a mystery. We provide evidence here that, heat shock proteins (HSPs), when released into the tumor microenvironment, is the immunogen necessary for priming concomitant tumor specific immunity. These responses require CD91- the endocytic and signaling receptor for the immunogenic HSPs. In our study, we generated cd11c-specific CD91 knockout mice and showed that tumors grew faster in those knockout mice, compared to CD91+/+ mice. In addition, we abrogated the interaction of tumor-derived HSP with CD91 in vivo by over-expression of Receptor Associated Protein (RAP), an endogenous inhibitor of CD91. The data showed that: first, tumors expressing RAP grew with significantly faster kinetics than the non-RAP expressing counterparts in wild type mice, although this difference was non-existent in immunocompromised mice and the inherent proliferative rates of tumors with or without RAP were identical; second, RAP-expressing tumors, when used as an immunogen in tumor prophylaxis, were significantly less efficient in priming immune responses; third, we examined the competition for CD91 between RAP and tumor-derived HSP in vivo. In the presence of RAP, less amount of tumor-derived EGFP-labeled HSPs were taken up by APCs in draining lymph nodes. In summary, our study demonstrates that the HSP-CD91 pathway is critical for establishment of concomitant immunity. Considering that elevated RAP levels have been reported in colon cancer patients, we propose a novel mechanism of immune evasion for tumors expressing competing ligands for immune receptors such as CD91. Citation Format: Yu Jerry Zhou, Robert J. Binder. Inhibition of the heat shock protein receptor CD91 abrogates concomitant antitumor immunity. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr A55.

Abstract B37: The heat shock protein receptor CD91 is necessary for tumor antigen cross-priming in vivo.

Abstract Immunosurveillance mechanisms of tumors depend on the host's ability to cross-prime minute quantities of tumor antigens. We have investigated the role of tumor-derived heat shock proteins (HSPs) in transfer of tumor antigens from tumor cells to antigen presenting cells for two reasons; 1) HSPs are known to chaperone peptides in the cells. The chaperoned peptides reflect the entire antigenicity of the cell from which they are derived. 2) HSPs activate antigen presenting cells resulting in the provision of co-stimulatory molecules and cytokines. These two events require the cell surface receptor CD91 that is expressed on APCs. Here we have used a combination of CD91 inhibitors and CD91 knock-out mice to demonstrate that the HSP-CD91 interaction is crucial for developing concomitant immunity routinely seen in the tumor bearing host. This pathway is indispensable for cross-presentation when antigen levels are low. Considering that elevated levels of endogenous CD91 inhibitors have been reported in colon cancer patients, we propose a novel mechanism of immune evasion for tumors expressing competing ligands for immune receptors such as CD91. Citation Format: Yu Jerry Zhou, Robert J. Binder. The heat shock protein receptor CD91 is necessary for tumor antigen cross-priming in vivo. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B37.

Inhibition of the Heat Shock Protein receptor CD91 abrogate concomitant anti-tumor immunity (127.24)

Abstract Most tumors are capable of generating immune response in the bearing host, a phenomenon described as concomitant immunity. Since tumors lack the typical (foreign) PAMPs that provide signal 2 for T cell priming, the mechanism of how concomitant immunity is established remains a mystery. We provide evidence here that, heat shock proteins (HSPs), when released into the tumor microenvironment, is the immunogen necessary for priming concomitant tumor specific immunity. These responses require CD91- the endocytic and signaling receptor for the immunogenic HSPs. Our study abrogates the interaction of tumor-derived HSP with CD91 in vivo by over-expression of a natural inhibitor of CD91. The data shows that: first, tumors expressing CD91 inhibitor grew with significantly faster kinetics than the non-inhibitor expressing counterparts in wild type mice, although this difference was non-existent in immunocompromised mice and the inherent proliferative rates of tumors with or without inhibitor were identical; second, inhibitor-expressing tumors, when used as an immunogen in tumor prophylaxis, were significantly less efficient in priming immune responses. We also examined the competition for CD91 between the inhibitor and tumor-derived HSP in vivo. In summary, our study demonstrates that the HSP-CD91 pathway is critical for establishment of concomitant immunity. We propose a novel mechanism of immune evasion for tumors expressing competing ligands for immune receptors such as CD91.

The immunological era in melanoma treatment: new challenges for heat shock protein-based vaccine in the advanced disease

Introduction: Tumor-derived heat shock protein (HSP)–peptide complexes (HSPPCs) induced immunity against malignancies in preclinical trials, working across tumor types and bypassing the need to identify single immunogenic peptides. These results paved the way for the use of human gp96 obtained from autologous tumor samples as an anti-cancer vaccine.Areas covered: Autologous tumor-derived HSP gp96 peptide complex (HSPPC-96) vaccine is emerging as a tumor- and patient-specific cancer vaccine, with confirmed activity in several malignancies. It has been tested in Phase III clinical trials in advanced melanoma and kidney cancer with evidence for efficacy in patients with earlier stage disease. HSPPC-96-based vaccine demonstrated an excellent safety profile, thus emerging as a novel therapeutic approach with a suggestive role in cancer therapy. This review summarizes work on the use of HSPPC-96 as an autologous anti-tumor vaccine in advanced melanoma. Data were retrieved by PubMed and Medline research and using the authors' personal experience.Expert opinion: Further investigations are needed to understand the biological basis of immune functions in order to improve the clinical outcome of HSP-based cancer therapy. In the near future, the combination of HSP-based vaccines with other biological compounds might represent a successful strategy in the therapy of advanced melanoma.

Heat shock protein–peptide complex in the treatment of glioblastoma

Vaccination immunotherapies offer the promise of long-term tumor control, and preclinical trials have found promising results. Active immunotherapy uses the adaptive immune response to specifically kill tumor cells. Tumor-specific antigens are processed by antigen-presenting cells and recognized by specific effector lymphocytes. However, basic vaccination strategies with tumor lysates have been unsuccessful in inducing antiglioma immunity in clinical trials. Gliomas are known to modulate the activity of antigen-presenting cells to reduce antitumor immune activity. Recently, tumor-derived heat shock proteins have been found to more effectively activate the immune response. Widely expressed, heat shock proteins are thought to present protein peptide fragments in a format conducive to processing by antigen-presenting cells. As a part of the protein synthesis machinery, peptides complexed with heat shock proteins are effectively representative of antigens expressed by the cell; these peptides convey the specificity of this vaccination strategy. The heat shock protein–peptide vaccine is one of many promising immunotherapeutic strategies being evaluated in clinical trials. These can be broadly classified as active, passive and adoptive, each with advantages and disadvantages. Here, we compare and contrast heat shock protein–peptide vaccines with other immunotherapies and describe the outcomes of clinical trials to date.

Modulatory effects of tumor-derived heat shock protein in DNA vaccination against nasopharyngeal carcinoma

Use of anti-idiotype antibody vaccines is a promising strategy against tumor, however, their immunogenicity still need to be improved. Heat shock proteins (HSPs) have been shown to act as adjuvants when coadministered with peptides or given as fusion proteins and enhance the vaccination efficiency. To evaluate the enhancement of the potency of anti-idiotype antibody immunogenicity by heat shock protein gp96, C57BL/6 mice were immunized with three intramuscular inoculations of the G22 DNA and/or gp96 DNA vaccine. Control was inoculated with empty plasmid pcDNA3.1. The levels of G22-specific antibody and lymphocyte phenotype were measured by ELISA, fluorescence activated cell sorter (FACS) analysis, respectively. In the tumor protection experiment, the immunized mice were then challenged with CMT-93-G22 cells. The tumor size and the survival time of the animals were compared among these groups. The results showed that the efficacy of G22 DNA vaccine could be enhanced by coadministrating with gp96 DNA which might be relevant with activating CD8 +T cells. Furthermore, co-injection of G22 DNA with gp96 DNA could prolong the survival time and lessen the tumor size of the CMT-93-G22-bearing mice. Our study demonstrates for the first time that G22+gp96 DNA vaccine can induce comparable G22-specific CD8 +T cell response and is a promising candidate DNA vaccine for nasopharyngeal carcinoma.

Neoadjuvant and adjuvant strategies in renal cell carcinoma

The current standard treatment for early stage (I-III) renal cell cancer (RCC) is surgery. While the prognosis of stage I tumors is excellent, stage II and particularly stage III have a high risk of relapse. The adjuvant treatment of patients with RCC remains an area of investigation, with patient selection being a key aspect. There are currently two prognostic nomograms to establish the risk of relapse in patients with resected RCC. The results of earlier studies of adjuvant therapy, including the use chemotherapy and/or immunotherapy after nephrectomy have failed to show any benefit in the outcome of patients at risk of developing local recurrence or distant metastases. Two recent phase III trials with vaccines (autologous tumor cell vaccine and autologous tumor-derived heat shock protein peptide complex-96) have shown promising, albeit still preliminary, results. In the metastatic RCC setting, recent advances in the molecular understanding of oncogenic pathways have led to the development of new therapeutic strategies with the use of targeted therapies in the adjuvant setting. Neoadjuvant treatment is another treatment modality currently being evaluated for patients with early disease and in patients with metastatic RCC with inoperable primary tumors. The questions that remain unanswered include activity of these agents in early stages of the disease, patient selection, optimal start time of the adjuvant treatment, and finally, the optimal length of treatment.

Treatment outcomes of metastatic melanoma in the elderly patients: A retrospective analysis.

e19028 Background: Cutaneous melanoma (CM) incidence is rapidly rising in the elderly population resulting in treatment challenges and increased economic burden. Although old age is a marker of poor prognosis of melanoma, aging associated co morbidities, cognitive decline and social isolation confound the outcome results. This report describes our experience of treating elderly patients (pts) with metastatic melanoma (MM). Methods: Between October 2002 and October 2008, 26 elderly pts with MM, 16 males and 10 female, median ages 75 years (yrs), range 60- 90 yrs were treated at the University of Connecticut Health Center after informed consent on a standard treatment. Metastatic sites included soft tissue and or lymph nodes and or lung (13 pts) and liver and or brain and or bones (13 pts). 22 pts opted for treatment and received either single agent temozolomide (3 pts), combined chemotherapy containing carboplatin, vinblastine, temozolomide (CVT) (10 pts) or CVT plus interferon (IFN) (3 pts), high dose interleukin 2 (IL2), (2 pts), biochemotherapy (3 pts) or metastatectomy with tumor derived heat shock protein vaccine (clinical trial) (1 pt). Four pts declined treatment and were followed up (included in survival analysis). Results: All pts tolerated treatments well with expected side effects and no treatment associated mortality. The overall response rate is 58% (15 out of 26), with complete response in seven pts (27%), partial response in 8 pts (31%), progressive disease in 9 pts (35%) and stable disease in 3 pts (12%). The median survival (MS) of all patients is 15 months (mths) (range 3-74 mths). During 7 year follow up period, 17 pts have died of progressive disease while 9 pts are surviving (6 with disease and 3 with no evidence of disease). The median survivalof surviving patients is 15 mths (range 7-74 mths); while those who died of disease are 12 mths (range 4-18). Conclusions: Our experience suggests that elderly patients with metastatic melanoma respond to standard chemotherapeutic agents used either alone or in combination resulting in improved clinical outcomes in some. Laboratory studies are underway to understand biologic relevance of clinical responses of melanoma in elderly patients. No significant financial relationships to disclose.

Induction of Tumor-specific Immune Response by Gene Transfer of Hsp70-cell-penetrating Peptide Fusion Protein to Tumors in Mice

To induce a tumor-specific immune response by delivering tumor-associated antigens in tumor cells to antigen-presenting cells (APCs), we designed a fusion protein which consists of heat-shock protein 70 (Hsp70) and the C-terminal 34 amino acids of herpes simplex virus VP22 protein (VP22(268-301)), the former having a peptide binding domain and an ability to be recognized by APCs, and the latter able to achieve cell penetration. Hsp70-VP22(268-301), the fusion protein, was efficiently taken up by mouse dendritic cell (DC) line DC2.4. Major histocompatibility complex (MHC) class I-restricted presentation of an epitope peptide of ovalbumin (OVA) was examined in DC2.4, and Hsp70-VP22(268-301) significantly increased the presentation of the peptide compared with Hsp70. Electroporation-assisted injection of naked plasmid vector expressing Hsp70-VP22(268-301) (pHsp70-VP22(268-301)) into subcutaneous tumors of EG7-OVA, a mouse lymphoma-expressing OVA, significantly increased the survival of mice compared with the same treatment with pHSp70, a plasmid expressing Hsp70. Splenocytes from the pHsp70-VP22(268-301)-treated mice exhibited cytolytic activity against both EG7-OVA and the parent EL4, but not against mouse melanoma B16-F10, suggesting that not only OVA-derived antigens but those common to EG7-OVA and EL4 are delivered to APCs. These results provide a new therapeutic method to induce tumor-specific antitumor immunity without identifying nor isolating tumor-associated antigens.

Autologous tumor-derived heat-shock protein peptide complex-96 (HSPPC-96) in patients with metastatic melanoma

BackgroundGlycoprotein-96, a non-polymorphic heat-shock protein, associates with intracellular peptides. Autologous tumor-derived heat shock protein-peptide complex 96 (HSPPC-96) can elicit potent tumor-specific T cell responses and protective immunity in animal models. We sought to investigate the feasibility, safety, and antitumor activity of HSPPC-96 vaccines prepared from tumor specimens of patients with metastatic melanoma.MethodsPatients with a Karnofsky Performance Status >70% and stage III or stage IV melanoma had to have a metastasis >3 cm in diameter resectable as part of routine clinical management. HSPPC-96 tumor-derived vaccines were prepared in one of three dose levels (2.5, 25, or 100 μg/dose) and administered as an intradermal injection weekly for 4 consecutive weeks. In vivo induction of immunity was evaluated using delayed-type hypersensitivity (DTH) to HSPPC-96, irradiated tumor, and dinitrochlorobenzene (DNCB). The γ-interferon (IFNγ) ELISPOT assay was used to measure induction of a peripheral blood mononuclear cell response against autologous tumor cells at baseline and at the beginning of weeks 3, 4, and 8.ResultsAmong 36 patients enrolled, 72% had stage IV melanoma and 83% had received prior systemic therapy. The smallest tumor specimen from which HSPPC-96 was prepared weighed 2 g. Twelve patients (including 9 with stage IV and indicator lesions) had a negative DNCB skin test result at baseline. All 36 patients were treated and evaluable for toxicity and response. There were no serious toxicities. There were no observed DTH responses to HSPPC-96 or to autologous tumor cells before or during treatment. The IFNγ-producing cell count rose modestly in 5 of 26 patients and returned to baseline by week 8, with no discernible association with HSPPC-96 dosing or clinical parameters. There were no objective responses among 16 patients with stage IV disease and indicator lesions. Among 20 patients treated in the adjuvant setting, 11 with stage IV melanoma at baseline had a progression-free and overall survival of 45% and 82%, respectively, with a median follow-up of 10 years.ConclusionTreatment with autologous tumor-derived HSPPC-96 was feasible and safe at all doses tested. Observed immunological effects and antitumor activity were modest, precluding selection of a biologically active dose. Nevertheless, the 25-μg dose level was shown to be practical for further study.

HSPPC-96 vaccine in metastatic melanoma patients: from the state of the art to a possible future

Heat-shock proteins are highly conserved, stress-induced proteins with chaperone function for trafficking and delivering peptides within the different compartments of the cell. Tumor-derived heat-shock protein–peptide complexes (HSPPCs) can be used for vaccination against malignancies. In particular, the HSPPC-96-based vaccine vitespen (formerly Oncophage®) is the first autologous cancer vaccine made from individual patients’ tumors that has shown encouraging results in clinical trials. In Phase I and II clinical trials, this vaccine has shown activity on different malignancies, such as gastric cancer, colorectal cancer, pancreatic cancer, non-Hodgkin’s lymphoma and chronic myelogenous leukemia. In Phase III clinical trials in melanoma and kidney cancer, it demonstrated an excellent safety profile with almost no toxicity. Heat-shock protein-based vaccines can be considered as a novel therapeutic approach with a promising role in cancer management.