Renal cell carcinoma-associated antigen G250 encodes a naturally processed epitope presented by human leukocyte antigen-DR molecules to CD4(+) T lymphocytes

The co-delivery of adenovirus-based immune checkpoint vaccine elicits a potent anti-tumor effect in renal carcinoma

Immune-based checkpoint therapy has made significant progress in cancer treatment, but its therapeutic effect is limited. A replication-defective adenovirus (Ad) vaccine encoding tumor antigen carbonic anhydrase IX (CAIX) combined with Ad-encoding immune checkpoint PD-L1 was developed to treat renal carcinoma. Three tumor models, subcutaneous, lung metastasis and orthotopic tumor were established, and Ad vaccines were used to immunize them and evaluate the vaccine's therapeutic effect. Compared to the single Ad vaccine group, the subcutaneous tumor growth was significantly reduced in Ad-CAIX/Ad-PD-L1 combination group. Co-immunization of Ad-CAIX/Ad-PD-L1 enhanced the induction and maturation of CD11c+ or CD8+CD11c+ DCs in the spleen and tumor and promoted the strong tumor-specific CD8+ T cell immune responses. In vivo CD8 T cell deletion assay showed that the anti-tumor effect of the Ad-CAIX/Ad-PD-L1 vaccine was mainly dependent on functional CD8+ T cell immune responses. Furthermore, the Ad-CAIX/Ad-PD-L1 vaccine effectively inhibited tumor growth and lung metastasis in metastatic or orthotopic models. These results indicate that the combination strategy of the immune checkpoint vaccine shows promising potential as an approach for malignant tumor therapy.

A Phase I, Open-label, Dose-escalation, and Cohort Expansion Study to Evaluate the Safety and Immune Response to Autologous Dendritic Cells Transduced With AdGMCA9 (DC-AdGMCAIX) in Patients With Metastatic Renal Cell Carcinoma

Expression of carbonic-anhydrase IX (CAIX) in clear cell renal cell carcinoma (RCC) makes it an attractive vaccine target. We developed a fusion-gene construct, granulocyte-macrophage (GM) colony-stimulating factor+CAIX, delivered by an adenoviral vector (Ad) into autologous dendritic cells (DCs) in this phase 1 study. The injected immature DCs were expected to stimulate an antigen-specific immune response against CAIX expressing RCC. Three dose-escalation cohorts (5, 15, and 50×10 cells/administration) were injected intradermally q2wk×3 doses based on a 3+3 design. The primary objective was the safety of the injections. Secondary objectives were immune responses using enzyme-linked immunosorbent spot, a serum biomarker panel, and clinical response. Fifteen patients with metastatic RCC were enrolled, and 9 patients received all 3 doses. No serious adverse events were seen. There were 3 (33%) patients with grade 1 fatigue, 1 of whom subsequently experienced grade 2 fatigue. One patient (11%) experienced grade 1-2 leukopenia. Only 1 patient (11%) experienced grade 2 flu-like symptoms. Of the 9 patients who received treatment, 1 expired of progressive disease, 2 patients were lost to follow-up and 6 patients are alive. Of the 6 patients, 5 have progressive disease, and 1 has completed treatment with stable disease at 27 months follow-up. Immune response measurements appeared more robust in higher dose cohorts, which appeared to be related to patients with stable disease at 3 months. These early data show that autologous immature DC-AdGMCAIX can be safely given to metastatic RCC patients without any serious adverse events with CAIX-specific immune response elicited by the treatment. These preliminary data support further study of Ad-GMCAIX, particularly with combination therapies that may enhance clinical activity.

Co-immunization with L-Myc enhances CD8+ or CD103+ DCs mediated tumor-specific multi-functional CD8+ T cell responses

Renal carcinoma shows a high risk of invasion and metastasis without effective treatment. Herein, we developed a chitosan (CS) nanoparticle-mediated DNA vaccine containing an activated factor L-Myc and a tumor-specific antigen CAIX for renal carcinoma treatment. The subcutaneous tumor models were intramuscularly immunized with CS-pL-Myc/pCAIX or control vaccine, respectively. Compared with single immunization group, the tumor growth was significantly suppressed in CS-pL-Myc/pCAIX co-immunization group. The increased proportion and mature of CD11c⁺ DCs, CD8⁺ CD11c⁺ DCs and CD103⁺ CD11c⁺ DCs were observed in the splenocytes from CS-pL-Myc/pCAIX co-immunized mice. Furthermore, the enhanced antigen-specific CD8⁺ T lymphocyte proliferation, cytotoxic T lymphocyte (CTL) responses, and multi-functional CD8⁺ T cell induction were detected in CS-pL-Myc/pCAIX co-immunization group compared with CS-pCAIX immunization group. Of note, the depletion of CD8 T cells resulted in the reduction of CD8⁺ T cells or CD8⁺ CD11c⁺ DCs and the loss of anti-tumor efficacy induced by CS-pL-Myc/pCAIX vaccine, suggesting the therapeutic efficacy of the vaccine was required for CD8⁺ DCs and CD103⁺ DCs mediated CD8⁺ T cells responses. Likewise, CS-pL-Myc/pCAIX co-immunization also significantly inhibited the lung metastasis of renal carcinoma models accompanied with the increased induction of multi-functional CD8⁺ T cell responses. Therefore, these results indicated that CS-pL-Myc/pCAIX vaccine could effectively induce CD8⁺ DCs and CD103⁺ DCs mediated tumor-specific multi-functional CD8⁺ T cell responses and exert the anti-tumor efficacy. This vaccine strategy offers a potential and promising approach for solid or metastatic tumor treatment.

Current status of antigen-specific T-cell immunotherapy for advanced renal-cell carcinoma

In renal-cell carcinoma (RCC), tumor-reactive T-cell responses can occur spontaneously or in response to systemic immunotherapy with cytokines and immune checkpoint inhibitors. Cancer vaccines and engineered T-cell therapies are designed to selectively augment tumor antigen-specific CD8⁺ T-cell responses with the goal to elicit tumor regression and avoid toxicities associated with nonspecific immunotherapies. In this review, we provide an overview of the central role of T-cell immunity in the treatment of advanced RCC. Clinical outcomes for antigen-targeted vaccines or other T-cell-engaging therapies for RCC are summarized and evaluated, and emerging new strategies to enhance the effectiveness of antigen-specific therapy for RCC are discussed.

An enhanced immune response against G250, induced by a heterologous DNA prime‑protein boost vaccination, using polyethyleneimine as a DNA vaccine adjuvant

The heterologous DNA prime‑protein boost vaccination approach has been widely applied as an immune treatment for carcinoma. However, inefficient delivery of DNA remains a major issue. In the present study, polyethyleneimine (PEI) was used as a DNA vector carrier to improve the transfection efficiency of the DNA vaccine and stimulate the humoral and cellular immunity against the renal carcinoma‑associated antigen G250. A protein vaccine was included in the immunization strategy in order to produce a prime‑boost effect. A DNA plasmid encoding an antigen G250 fragment was constructed and complexed with PEI. A protein vaccine against G250 was expressed in BL21 (DE3) Escherichia coli cells, by transformation with a pET28a(+)/C‑G250 plasmid. The protein was purified using a nickel‑nitriloacetic acid purification system. The in vitro transfection efficiency of the DNA vaccine was analyzed in HEK293 human endothelial kidney cells. The in vitro transfection efficiency in HEK293 cells was highest 48 h after transfection. Furthermore, mice were primed with 200 µg pVAX1/C‑250 plasmid complexed with PEI, and boosted using 50 µg of purified C‑G250 protein. In order to evaluate the immune response the antibody titer, splenocyte response, and interferon‑γ levels from CD8+ T‑cell splenocytes were analyzed using ELISA, lymphocyte proliferation or enzyme‑linked immunosorbent spot assays. Firstly, the pVAX1/C‑G250 plasmid was shown to be constructed successfully. As compared with the DNA group, the antibody titer, lymphocyte proliferation percentage, and cytokine production level induced by the DNA‑PEI and DNA‑PEI+C‑G250 groups were significantly higher. Furthermore, the DNA‑PEI+C‑G250 group exhibited the strongest humoral and cellular response. Owing to the adjuvant effect of PEI, the pVAX1/C‑G250‑PEI prime plus C‑G250 protein boost regimen could induce a strong immune response, and has been proved to be a potent vaccine candidate against renal cell carcinoma.

Foxp3+ T cells inhibit antitumor immune memory modulated by mTOR inhibition

Inhibition of mTOR signaling enhances antitumor memory lymphocytes. However, pharmacologic mTOR inhibition also enhances regulatory T-cell (Treg) activity. To counter this effect, Treg control was added to mTOR inhibition in preclinical models. Tregs were controlled with CD4-depleting antibodies because CD4 depletion has high translational potential and already has a well-established safety profile in patients. The antitumor activity of the combination therapy was CD8 dependent and controlled growth of syngeneic tumors even when an adoptive immunotherapy was not used. Lymphocytes resulting from the combination therapy could be transferred into naïve mice to inhibit aggressive growth of lung metastases. The combination therapy enhanced CD8 memory formation as determined by memory markers and functional studies of immune recall. Removal of FoxP3-expressing T lymphocytes was the mechanism underlying immunologic memory formation following CD4 depletion. This was confirmed using transgenic DEREG (depletion of regulatory T cells) mice to specifically remove Foxp3(+) T cells. It was further confirmed with reciprocal studies where stimulation of immunologic memory because of CD4 depletion was completely neutralized by adoptively transferring tumor-specific Foxp3(+) T cells. Also contributing to tumor control, Tregs that eventually recovered following CD4 depletion were less immunosuppressive. These results provide a rationale for further study of mTOR inhibition and CD4 depletion in patients.

Spontaneous peripheral T-cell responses toward the tumor-associated antigen cyclin D1 in patients with clear cell renal cell carcinoma

Renal cell carcinoma (RCC) is a heterogeneous group of kidney cancers with clear cell RCC (ccRCC) as the major subgroup. To expand the number of clinically relevant tumor-associated antigens (TAA) that can be targeted by immunotherapy, we analyzed samples from 23 patients with primary ccRCC for the expression and immunogenicity of various TAAs. We found high-frequency expression of MAGE-A9 and NY-ESO-1 in 36% and 55% of samples, respectively, and overexpression of PRAME, RAGE-1, CA-IX, Cyclin D1, ADFP, C-MET, and RGS-5 in many of the tumor samples. We analyzed the blood of patients with HLA-A2(+) ccRCC for the presence of CD8(+) T cells specific for TAA-derived HLA-A2-restricted peptides and found spontaneous responses to cyclin D1 in 5 of 6 patients with Cyclin D1-positive tumors. Cyclin D1-specific CD8(+) T cells secreted TNF-α, IFN-γ, and interleukin-2 (IL-2), and degranulated, indicating the presence of polyfunctional tumor-specific CD8(+) T cells in the blood of these patients with ccRCC. The high frequency (43%) of Cyclin D1 overexpression and the presence of functional cyclin D1-specific T cells in 83% of these patients with ccRCC suggest that cyclin D1 may be a target for immunotherapeutic strategies.

Generation of anti-tumour immune response using dendritic cells pulsed with carbonic anhydrase IX-Acinetobacter baumannii outer membrane protein A fusion proteins against renal cell carcinoma

Carbonic anhydrase IX (CA9), a specific molecular marker for renal cell carcinoma (RCC), serves as a potential target for RCC-specific immunotherapy using dendritic cells (DCs). However, pulsing of DCs with CA9 alone is not sufficient for generation of a therapeutic anti-tumour immune response against RCC. In this study, in order to generate a potent anti-tumour immune response against RCC, we produced recombinant CA9-Acinetobacter baumannii outer membrane protein A (AbOmpA) fusion proteins, designated CA9-AbOmpA, and investigated the ability of DCs pulsed with CA9-AbOmpA fusion proteins in a murine renal cell carcinoma (RENCA) model. A recombinant CA9-AbOmpA fusion protein was composed of a unique proteoglycan-related region of CA9 (1-120 amino acids) fused at the C-terminus with transmembrane domain of AbOmpA (1-200 amino acids). This fusion protein was capable of inducing DC maturation and interleukin (IL)-12 production in DCs. Interaction of DCs pulsed with CA9-AbOmpA fusion proteins with naive T cells stimulated secretion of IL-2, interferon (IFN)-γ and tumour necrosis factor (TNF)-α in T cells. Lymphocytes harvested from mice immunized with DCs pulsed with CA9-AbOmpA fusion proteins secreted IFN-γ and showed a specific cytotoxic activity against CA9-expressing RENCA (RENCA-CA9) cells. Administration of CA9-AbOmpA-pulsed DC vaccine suppressed growth of RENCA-CA9 cells in mice with an established tumour burden. These results suggest that DCs pulsed with CA9-AbOmpA fusion proteins generate a specific anti-tumour immune response against RCC, which can be utilized in immunotherapy of RCC.

Immunostimulatory activity of dendritic cells pulsed with carbonic anhydrase IX and Acinetobacter baumannii outer membrane protein A for renal cell carcinoma

Dendritic cell (DC)-based immunotherapy is a potent therapeutic modality for treating renal cell carcinoma (RCC), but development of antigens specific for tumor-targeting and anti-tumor immunity is of great interest for clinical trials. The present study investigated the ability of DCs pulsed with a combination of carbonic anhydrase IX (CA9) as an RCC-specific biomarker and Acinetobacter baumannii outer membrane protein A (AbOmpA) as an immunoadjuvant to induce anti-tumor immunity against murine renal cell carcinoma (RENCA) in a murine model. Murine bone-marrow-derived DCs pulsed with a combination of RENCA lysates and AbOmpA were tested for their capacity to induce DC maturation and T cell responses in vitro. A combination of RENCA lysates and AbOmpA up-regulated the surface expression of co-stimulatory molecules, CD80 and CD86, and the antigen presenting molecules, major histocompatibility (MHC) class I and class II, in DCs. A combination of RENCA lysates and AbOmpA also induced interleukin-12 (IL-12) production in DCs. Next, the immunostimulatory activity of DCs pulsed with a combination of CA9 and AbOmpA was determined. A combination of CA9 and AbOmpA up-regulated the surface expression of co-stimulatory molecules and antigen presenting molecules in DCs. DCs pulsed with a combination of CA9 and AbOmpA effectively secreted IL-12 but not IL-10. These cells interacted with T cells and formed clusters. DCs pulsed with CA9 and AbOmpA elicited the secretion of interferon-γ and IL-2 in T cells. In conclusion, a combination of CA9 and AbOmpA enhanced the immunostimulatory activity of DCs, which may effectively induce anti-tumor immunity against human RCC.

About human tumor antigens to be used in immunotherapy

The choice of antigens to be used in cancer immunotherapy remains a crucial and difficult issue. This review highlights some properties of the different groups of human tumor antigens recognized by T lymphocytes, focusing on parameters that should influence this choice, such as tumor specificity and level of antigen expression.

Evaluation of renal cell carcinoma vaccines targeting carbonic anhydrase IX using heat shock protein 110

Carbonic anhydrase IX (CA9) is a renal cell carcinoma (RCC)-specific tumor protein that is targeted using heat shock protein 110 (hsp110). The chaperoning ability of hsp110 can be utilized to form a complex with CA9 (hsp110 + CA9) in vitro, which can be administered as a highly concentrated tumor vaccine. In a tumor prevention model, hsp110 + CA9 prevented the growth of RENCA tumors in BALB/c mice, and produced IFN-gamma response measured using ELISPOT and an antibody response measured using ELISA. To test a second vaccine strategy, hsp110 complexed to a previously described CA9 peptide prevented tumor growth and produced a very weak IFN-gamma response, but no antibody response. A plasmid vector containing grp170, a member of the hsp110 family, linked to CA9 did not produce an antitumor response and produced no IFN-gamma response or antibodies. In a model of metastatic RCC, RENCA cells were injected intradermally prior to vaccination. Hsp110 + CA9 decreased tumor growth compared to control vaccinations. These studies suggest that recombinant hsp110 complexed to CA9 should be evaluated for treatment of RCC.

Preliminary analysis of patients with progressive renal cell carcinoma vaccinated with CA9-peptide-pulsed mature dendritic cells

Carbonic anhydrase-IXG250/MN (CA9) is a renal cell carcinoma (RCC)-associated antigen ubiquitously expressed in the clear-cell subtype of RCC. Two CA9-derived peptides have been identified defining a cytotoxic T-lymphocyte epitope and human leukocyte antigen (HLA)-DR epitope, able to induce T-cell responses in vitro. A phase I clinical trial was performed with CA9-peptide-loaded dendritic cells (DCs) in patients with progressive, cytokine-refractory metastatic RCC to assess the safety, toxicity, and induction of CA9-specific immunity. Patients with objective progressive metastatic RCC received 5 vaccinations of mature DCs pulsed with the CA9-derived peptides and keyhole limpet hemocyanine (KLH). Peripheral blood was collected at regular intervals, delayed-type hypersensitivity (DTH) was tested at baseline and after the last vaccination, and skin biopsies of positive DTH sites were collected for immunomonitoring purposes. Patients were also monitored for clinical responses. No significant toxicity was observed. All patients developed humoral responses against KLH, and demonstrated DTH conversion. Evaluation of biopsy material suggested an increased influx of T-helper cells. In none of the immunomonitoring assays was evidence for the induction of CA9-peptide-specific immunity observed. No clinical responses were observed. The vaccination of DCs pulsed with KLH and 2 CA9-derived peptides was well tolerated. The lack of induction of CA9-peptide-specific immune responses indicates that this particular vaccine regimen is poor in inducing CA9-peptide-specific immune responses.

Peptidome from renal cell carcinoma contains antigens recognized by CD4+ T cells and shared among tumors of different histology

PURPOSE

Renal cell carcinoma (RCC) is considered immunogenic; nonetheless, rare tumor-associated antigens have been identified or are expressed in RCC. Peptidome (i.e., the total content of natural peptides of whole cells) from other tumors, such as melanoma, has proved to be immunogenic. The aims of this study were to determine whether peptidome from RCC is immunogenic and whether it contains tumor peptides shared among allogenic RCCs.

EXPERIMENTAL DESIGN

Autologous dendritic cells pulsed with RCC peptidome were used to activate in vitro CD4(+) T cells from healthy donors and a metastatic RCC patient. CD4(+) T-cell polyclonal lines and clones were characterized for tumor cell recognition by proliferation assay, killing activity, and cytokine secretion.

RESULTS

CD4(+) T-cell lines and clones recognized HLA-DR-matched allogenic RCC and, for the patient, the autologous tumor. RCC-reactive CD4(+) T cells showed a heterogeneous Th1 or Th0/Th2 pattern of cytokine secretion. Moreover, RCC-reactive CD4(+) T cells recognized also melanoma, colon carcinoma, cervical carcinoma, pancreas carcinoma, lung carcinoma, gastric carcinoma, and lymphoma cells but not autologous T-cell blasts.

CONCLUSIONS

Our results show that (a) the RCC peptidome contain antigens recognized by CD4(+) T cells and (b) shared among tumors of different histology and (c) it induces both Th1-type and Th2/Th0-type immune responses. These data support the use of the peptidome from allogenic RCC for specific immunotherapy in RCC and possibly in other neoplastic diseases. Moreover, the CD4(+) T-cell clones generated here are useful tools for tumor antigen identification.

RENCA/carbonic anhydrase-IX: a murine model of a carbonic anhydrase-IX-expressing renal cell carcinoma

OBJECTIVES

Carbonic anhydrase-IX (CA-IX) is a cell surface tumor-associated antigen expressed by most clear cell renal cell carcinomas (RCCs). The specificity and the prognostic value of CA-IX provide impetus to create a mouse model of CA-IX-expressing RCC for testing CA-IX-targeted therapies against RCC.

METHODS

A retrovirus encoding the human CA-IX gene was used to transduce the murine RCC line, RENCA. In vivo growth kinetics and CA-IX expression were compared between RENCA and RENCA/CA-IX using heterotopic, metastatic, and orthotopic models.

RESULTS

Transduction of RENCA created the RENCA/CA-IX line with nearly 100% CA-IX surface expression. In the heterotopic model, subcutaneous injection of 500,000 and 50,000 cells led to tumor formation at 2 to 2.5 weeks after injection, with similar growth kinetics between the two cell lines at either cell number. In the pulmonary metastatic model, a similar number of metastases was noted after inoculation of RENCA and RENCA/CA-IX. In the orthotopic model, autopsy revealed a CA-IX-expressing renal tumor, as well as CA-IX-expressing metastases to the lungs, liver, contralateral kidney, intestines, and lymph nodes. In all the above models, the RENCA/CA-IX tumors retained expression of CA-IX, as demonstrated by immunohistochemistry staining.

CONCLUSIONS

RENCA/CA-IX is the first tumor model that manifests in immunocompetent Balb/c mice and stably expresses a defined kidney cancer-associated antigen. It maintains antigen expression, forms metastases, and produces reliable tumor growth kinetics equivalent to that of its parental cell line.

Tumor stroma-associated antigens for anti-cancer immunotherapy

Immunotherapy has been widely investigated for its potential use in cancer therapy and it becomes more and more apparent that the selection of target antigens is essential for its efficacy. Indeed, limited clinical efficacy is partly due to immune evasion mechanisms of neoplastic cells, e.g. downregulation of expression or presentation of the respective antigens. Consequently, antigens contributing to tumor cell survival seem to be more suitable therapeutic targets. However, even such antigens may be subject to immune evasion due to impaired processing and cell surface expression. Since development and progression of tumors is not only dependent on cancer cells themselves but also on the active contribution of the stromal cells, e.g. by secreting growth supporting factors, enzymes degrading the extracellular matrix or angiogenic factors, the tumor stroma may also serve as a target for immune intervention. To this end several antigens have been identified which are induced or upregulated on the tumor stroma. Tumor stroma-associated antigens are characterized by an otherwise restricted expression pattern, particularly with respect to differentiated tissues, and they have been successfully targeted by passive and active immunotherapy in preclinical models. Moreover, some of these strategies have already been translated into clinical trials.

Adjuvant treatment for renal cell carcinoma

Despite significant advances in the diagnosis, staging and treatment of patients with renal cell carcinoma, recurrence rates following surgical resection of locally aggressive tumours remain high. In an effort to delay disease progression and improve survival, the concept of adjuvant therapy has been proposed. Optimal adjuvant therapy for surgically resected renal cell carcinoma remains to be defined and the evaluation of adjuvant therapies will require properly controlled and adequately powered randomised trials. Promising preliminary results have been seen with active immunotherapies and agents that target critical signalling pathways, and there are several Phase III trials of these novel treatment options that are underway. In addition, classification of patients into high- and low-risk subgroups on the basis of a prognosis profile will serve as a useful means to guide clinicians in improving the selection of patients who are likely to derive benefit from adjuvant therapy. This will lead to a future area of investigation, which will be the identification of patients within the target population that should respond to a given treatment. This review will discuss the role and current status of adjuvant therapies for renal cell carcinoma.

Molecularly targeted therapy in renal cell carcinoma

Recent developments in the molecular biology of renal cell carcinoma have identified multiple pathways associated with the development of this cancer. Multiple strategies have been investigated targeting these pathways, with significant clinical benefits shown in early studies. This review aims to overview the findings of recent clinical trials and clarify the development of these compounds for use in renal cell carcinoma. The authors also aim to clarify the molecular pathways implicated in renal cell carcinoma and the clinical results in metastatic renal cell carcinoma with agents targeting these pathways. The relevant literature was reviewed concerning pathways implicated in the pathophysiology of renal cell carcinoma including pathways activated secondary to von Hippel-Lindau gene inactivation and PI-3 kinase/Akt/mammalian target of rapamycin pathway activation. Therapeutic targeting based upon underlying molecular biology in renal cell carcinoma has strong rationale. Substantial clinical activity has been reported with various agents targeting these pathways, most notably with vascular endothelial growth factor-targeted therapy. However, investigation is needed to optimally utilize these agents at the appropriate stage of disease and in the best combinations for maximal clinical benefit.

Carbonic anhydrase IX and the future of molecular markers in renal cell carcinoma

The use of carbonic anhydrase IX as a promising molecular marker in RCC is described by authors from Los Angeles, who discuss the promise that molecular markers hold to improve diagnosis, staging, treatment, surveillance and survival of patients with RCC. There is a whole range of new treatments being introduced in the management of metastatic renal cancer. The use of VEGF-targeted therapy has particular importance, especially as it has a strong genetically linked rationale for its potential success in this area. Authors from the USA show that substantial clinical activity has been reported in initial clinical trials. In prostate cancer, drugs targeting microtubules, such as taxanes, have already been introduced clinically, and their success has received widespread attention. A new group of drugs, the epothilones, have similar but not identical binding properties to microtubules, and authors from the USA describe how they have shown activity in hormone-refractory prostate cancer, and are moving to phase III testing.

Novel treatments for metastatic renal cell carcinoma

The mainstay of any curative treatment in renal cell carcinoma (RCC) is surgery. In case of metastatic disease at presentation a radical nephrectomy is recommended to good performance status patients prior to start of interferon-alfa treatment. Interferon-alpha (IFN-alpha) offers in a small but significant percentage of patients advantage in overall survival; interleukin-2 (IL-2) based therapy gives similar survival rates. To date hormonal and chemotherapy do not have a proven impact on survival. The recent new insights in the molecular biology of clear RCC has revealed a key-role for vascular endothelial growth factor (VEGF) in the stimulation of angiogenesis in this highly vascularized tumour. This opens interesting new treatment strategies including: blockage of VEGF with the monoclonal antibody bevacizumab and inhibition of VEGF receptor tyrosine kinases (with small oral molecules such as SU11248 or PTK787). Likewise, inhibition of the Raf kinase pathway (with oral Bay 43-9006) or inhibition of the mTOR pathway (with i.v. CCI-779) are under investigation. Preliminary clinical results with all these compounds are interesting and the results of ongoing phase III studies will become available in the next years.

Novel treatment strategies in clear-cell metastatic renal cell carcinoma

Metastatic renal-cell carcinoma (mRCC) is highly resistant to cytotoxic agents or hormones and is currently mainly treated with cytokine-based therapy. Transient responses and moderate survival advantages have been achieved in a subset of patients with these aspecific biological response modifiers. Side-effects are considerable, especially with high-dose interleukin (IL)-2. Efforts made in the field of specific immunotherapy have focused on optimization of dendritic cell vaccination and on administration of monoclonal antibodies, either cold (unconjugated) or hot (radioactively labeled). Furthermore, allogeneic bone marrow transplantation is able to induce remissions but, regrettably, is related to substantial morbidity and mortality. Neutralization of the biological activity of some immunosuppressive cytokines produced by RCC (IL-6 and tumor necrosis factor-alpha) with monoclonal antibodies is currently under investigation. Insights gained into the processes and pathways underlying carcinogenesis have led to the development of new treatment strategies. These treatments can be used for clear cell RCC, since they focus on blocking gene products that are upregulated by mutations in the von Hippel-Lindau gene. Specific strategies include anti-vascular endothelial growth factor monoclonal antibody (bevacizumab) or inhibition of its receptor kinases (oral SU11248 or PTK787), or targeting the Raf kinase pathway (by BAY 43-9006) or the mammalian target of rapamycin (mTOR) pathway (by CCI-779). Early clinical results are promising, but their place in the treatment of RCC has to be determined.

Renal cell carcinoma 2005: new frontiers in staging, prognostication and targeted molecular therapy

PURPOSE

Renal cell carcinoma (RCC) has traditionally been staged using a purely anatomical staging system. Although current staging systems provide good prognostic information, data published in the last few years has led to significant controversies as to whether further revisions are needed and whether improvements can be made with the introduction of new, more accurate and predictive prognostic factors not currently included in traditional staging systems. This review highlights such controversies and provides an update on current staging modalities, prognostic factors and targeted molecular therapy for RCC.

MATERIALS AND METHODS

A comprehensive review of the peer reviewed literature was performed on the topic of current staging modalities, validated prognostic factors, predictive nomograms, molecular markers and targeted molecular therapy for RCC.

RESULTS

A staging system for malignant disease such as RCC uses various characteristics of tumors to stratify patients into clinically meaningful categories, which can be used to provide patients with counseling regarding prognosis, select treatment modalities and determine eligibility for clinical trials. The TNM staging system is currently the most extensively used one. However, it has undergone recent systematic revision due to rapidly emerging data from longer patient followup. The identification of various histological and symptomatic factors has led groups at many centers to develop more comprehensive staging systems that integrate these factors and include patients with metastatic and local disease. While integrated staging systems have improved RCC staging, the recent discovery of molecular tumor markers is expected to revolutionize RCC staging in the future and lead to the development of new therapies based on molecular targeting.

CONCLUSIONS

Staging systems for RCC serve as a valuable prognostic tool. Several new patient and tumor characteristics have been reported to be important prognostic factors and they have been integrated into current staging systems. In addition, the field of RCC is rapidly undergoing a revolution led by molecular markers and targeted therapies. With this information urologists will be updated with the most current and comprehensive staging strategies, and be provided with a glimpse of the molecular and patient specific staging and treatment paradigms that will in our opinion transform the future management of this malignancy.

Novel approaches in the therapy of metastatic renal cell carcinoma

Renal cell carcinoma (RCC) is the most lethal of the common urologic malignancies, with approximately 40% of patients eventually dying of cancer progression. Approximately one third of patients present with metastatic disease, and up to 40% treated for localized disease have a recurrence. Recent advances in the understanding of the pathogenesis, behavior, and molecular biology of RCC have paved the way for developments that may enhance early diagnosis, better predict tumor prognosis, and improve survival for RCC patients. The recent discovery of molecular tumor markers is expected to revolutionize the staging of RCC in the future and lead to the development of new therapies based on molecular targeting. Cytokine-based immunotherapy can be considered standard therapy in the treatment of metastatic RCC today. However, new therapies such as tumor vaccines, anti-angiogenesis agents, and small molecule inhibitors are being developed to improve efficacy and treat those patients who are unable to tolerate or are resistant to systemic immunotherapy. The aim of this review is to provide an update on current therapeutic approaches and targeted molecular therapy for metastatic RCC.

Antigenic targets for renal cell carcinoma immunotherapy

Renal cell carcinoma (RCC) has been shown to respond to immunotherapeutic intervention, thus fostering continued interest in exploiting the ability of the immune system to recognise and eradicate renal malignancy. Considerable progress in the characterisation of tumour-associated antigens, coupled with the appreciation that dendritic cells act as master regulators of immunity and tolerance, has opened new possibilities for immunotherapeutic intervention against human cancer. However, in contrast to other tumour systems, clinically relevant antigens expressed by RCC have not yet been identified. Therefore, most RCC vaccine trials have employed unfractionated antigens derived from tumour cells, with the goal of eliciting T cell responses against many unknown antigens expressed by the tumour. The recent discovery of genes with critical roles in oncogenesis has facilitated the identification of novel, more universal targets that may make cancer vaccines more practical, applicable and, potentially, more effective. In addition, immunisation against tumour antigens can be combined with tumour stroma-associated targets, thereby exerting a synergistic antitumour effect. Continued identification of molecular targets, in concert with more effective vaccination protocols, is likely to produce vaccination strategies with clinical impact.

Simultaneous expression of T-cell activating antigens in renal cell carcinoma: implications for specific immunotherapy

PURPOSE

The activation of antigen specific T cells by tumor associated antigens (TAA) might be a promising treatment strategy for patients with renal cell carcinoma (RCC). We analyzed TAA expression in patients with RCC as well as the prevalence of fitting HLA phenotypes and calculated the percent of patients eligible for peptide vaccination trials.

MATERIALS AND METHODS

A total of 41 RCC samples from primary tumors were analyzed for TAA expression by reverse transcriptase-polymerase chain reaction. Genes of interest were MAGE-1, MAGE-3, G250 and PRAME since peptides derived from these genes have been shown to activate antigen specific cytotoxic T lymphocytes. Results were combined with data on the HLA gene and haplotype frequencies in the German population as an example of a white population.

RESULTS

Tumor specific expression of at least 1 T-cell activating antigen was observed in all patients. Of the patients 80% expressed 2 or more TAAs simultaneously. HLA molecules suitable for presentation of the respective antigens were calculated to be expressed in 51% to 85% of white German patients. These results mirror with only minor variations most of the white populations in Europe and North America.

CONCLUSIONS

We noted that T-cell activating tumor associated antigens are frequently expressed in patients with RCC. Based on HLA expression analysis in a white population at least 30% of patients with RCC are eligible for monovalent specific immunotherapy and 41% are eligible for polyvalent specific immunotherapy. These data are a rational basis for future prospective vaccination trials in patients with RCC.

Generation of Kidney Cancer-Specific Antitumor Immune Responses Using Peripheral Blood Monocytes Transduced With a Recombinant Adenovirus Encoding Carbonic Anhydrase 9

PURPOSE

Carbonic anhydrase 9 (CA9) is the most promising molecular marker described for renal cell carcinoma (RCC) to date. We investigated whether transduction of monocytes from peripheral blood with adenovirus encoding the CA9 gene (AdV-CA9) could stimulate a T-cell mediated immune response against cancer cells expressing CA9. The ability to consistently generate a T-cell response is an important step toward the development of a CA9-specific RCC vaccine.

EXPERIMENTAL DESIGN

AdV-CA9 was generated using the AdEasy system. AdV-CA9-transduced peripheral blood mononuclear cell (PBMC)-derived monocytes were used to raise CTLs from autologous peripheral blood lymphocytes (PBLs). The ability of CTLs to lyse targets expressing CA9 was assessed by (51)Cr-release.

RESULTS

Monocytes were efficiently transduced with AdV-CA9. In five of six experiments, AdV-CA9-transduced monocytes were able to induce a population of CTLs from bulk PBLs. CTLs were capable of lysing autologous, but not allogeneic monocytes expressing CA9. Furthermore, CTLs were able to lyse autologous RCC tumor cells expressing CA9. The ability of CTLs to lyse relevant targets was blocked by anti-CD3, anti-CD8, and anti-MHC class I antibodies demonstrating a MHC class I restricted response.

CONCLUSIONS

These results suggest that PBMC-derived monocytes transduced with AdV-CA9 can generate RCC-specific MHC class I restricted CTLs capable of lysing CA9-expressing cancer cells. Transduction of PBMC-derived monocytes with adenovirus provides a simple and effective alternative to the use of dendritic cells for the induction of antigen-specific CTL.

Epitope-based vaccines: an update on epitope identification, vaccine design and delivery

The basic premise of the epitope-based approach to vaccine development is that, in certain cases, the responses induced by the natural immunogen are not optimal, and can be improved upon by isolation or optimization of specific components of the response. For example, immunodominance is a key factor limiting the type and breadth of adaptive immunity. Recent advances in understanding the mechanisms of immunodominance thus represent an opportunity to further develop the epitope-based approach.

Immunotherapy for renal cell carcinoma

Renal cell carcinoma (RCC) is the most prevalent malignancy within the kidney and the incidence is rising. Due to improved radiological evaluation over 50% of the renal cancers are found incidentally. Despite the fact that these incidentalomas are often confined to the kidney, around 50% of all patients diagnosed with kidney cancer will develop systemic disease. Metastatic RCC has a poor prognosis. Traditional treatment modalities like chemo- and radiotherapy show overall response percentages of 2-6%. In view of the observed spontaneous remissions of advanced renal cancer, immune mechanisms have been suggested to play a role in the natural disease course of RCC. At present, several non-specific cytokine regimens are used in the treatment of mRCC, e.g. interleukin-2 and interferon-alpha, in combination or as monotherapy or in combination with substances like 13-cis-retinoic acid and/or 5-fluorouracil. Collective data of trials evaluating cytokine-based therapies for mRCC show an overall response rate of approximately 15%, with 5% of the patients showing complete responses. More importantly, cytokine treatment clearly translates into a significant survival benefit in a subset of patients. Nevertheless, the toxicity profile of these cytokine regimens is significant. With the enhanced knowledge of tumor-immunology, the identification of immunogenic tumor proteins, and antibodies recognizing tumor-associated antigens, new treatment strategies with increased specificity and fewer side effects are of interest. Here we review the different immunotherapeutical modalities currently used as well as new approaches for the treatment of advanced RCC.

Stimulation of tumor-reactive T lymphocytes using mixtures of synthetic peptides derived from tumor-associated antigens with diverse MHC binding affinities

The use of reverse immunology may be necessary to identify new tumor-associated antigens, particularly for cancers, against which tumor-reactive T cell populations have been difficult to establish. One approach has been to screen peptides derived from a candidate antigen with high major histocompatibility complex (MHC) binding affinities for the induction of tumor-reactive T lymphocytes in vitro. However, many candidate antigens that are overexpressed in tumors are nonmutated self-proteins, and unlike foreign or mutated proteins, immunodominant epitopes may not be expressed at high density on the surface of tumor cells. Therefore, to identify tumor-associated epitopes, it may be necessary to screen large panels of peptides with wide ranges of MHC binding affinities. The current methodology of stimulating peripheral blood lymphocytes (PBL) from donors expressing the MHC molecule of interest with individual peptides is impractical for screening such large panels. Therefore, we evaluated the use of mixtures of peptides with variable MHC binding affinities for the induction of tumor-reactive T lymphocytes with the melanoma antigens gp100 and an alternate isoform of tyrosinase-related protein 2 (TRP2-6b) as models. A mixture of 10 known human leukocyte antigen (HLA)-A*0201-restricted peptides from gp100 induced melanoma-reactive cytotoxic T lymphoycte (CTL) from multiple patients with metastatic melanoma. The majority of these T cell populations recognized the known immunodominant epitopes gp100:209-217 and gp100:280-288, even though the HLA-A*0201 binding affinities of these peptides were much lower than other peptides in the mixture. Similarly, melanoma-reactive CTL were generated with a mixture of HLA-A*0201-restricted peptides from TRP2-6b, and these responses were directed against the previously identified tumor-associated epitopes TRP2-6b:180-188, TRP2-6b:288-296 and TRP2-6b:403-411. These results suggest that the use of peptide mixtures may facilitate the identification of new tumor-associated antigens through the application of reverse immunology.