Clinical research of genetically modified dendritic cells in combination with cytokine-induced killer cell treatment in advanced renal cancer

Renal cell carcinoma (RCC) accounts for about [1] 5% of all new cancer cases worldwide. It is estimated that 27, 0000 new cases will be diagnosed with renal cancer in the world [2] and its incidence is rising each year. Radical nephrectomy can be curative for early stage disease, but for those patients with distant metastases the prognosis is poor. After complete resection of the primary tumor, recurrence develops in another 30% of patients [3]. RCC remains a therapeutic challenge because of its resistance to conventional therapies such as radiation, chemotherapy, and hormonal therapy. Although immunotherapy using interleukin-2 (IL-2) or interferon-alpha (IFN-α) [4] has become an accepted standard treatment for patients with RCC benefits, it was limited to a minority of patients. Therefore, attempts to develop more effective and nontoxic therapeutic strategies are needed. Dendritic cells (DCs) are professional antigen-presenting cells, as they are endowed with the unique potential to activate anti-tumor effector T and B lymphocytes [5]. They have been applied in clinics. The first study using DC vaccination for patients with RCC was published in 1999 and altogether 225 clinical trials have been published so far. Cytokine-induced killer (CIK) cells, which are non-major histocompatibility complex (MHC)-restricted CD3⁺CD56⁺T cells, take advantage of the body’s natural ability to eliminate tumor cells by stimulating and restoring the immune system to recognize and kill tumor cells. The first clinical study applying autologous CIK cells for cancer therapy was performed by Schmidt-Wolf and colleagues in 1999 [6].

Recently, clinical trials were performed aiming at combining active immune therapy using tumor vaccines with passive immunotherapy using CIK cells [7]. Evidence is rising that the application of CIK cells in combination with pulsed DC may indeed improve the immune response towards cancer. To improve therapeutic potency of CIK cells by vaccination, Sun et al. made use of DCs in combination with CIK cells for the treatment of relapsed or refractory non-Hodgkin’s lymphoma (NHL) [8]. After immunotherapy, the CD3⁺CD8⁺:CD3⁺ CD56⁺ T cell ratio was improved and IFN-gamma and IL-12 levels were higher in patients of the DCs–CIK group compared to the CIK group. Tumor volume was substantially decreased. Except of transient fever and chill, no remarkable adverse events happened during or after the treatment. Although a small number of patients were treated, data imply that DCs in combination with CIK cells exhibit an improved anti-tumor immune response.

In this study, we evaluated the efficacy and safety of genetically modified DCs in combination with CIK in patients with RCC.

Treatment of RCC, especially metastatic RCCs, confronts a great dilemma in clinical practice. Although there are a number of therapeutic options available such as the immuno-regulating cytokines and the new anti-angiogenic targeted agents at present, these are commonly toxic and rarely produce durable complete remissions. The recent considerable success of cell immunotherapy in melanoma warrants further efforts to apply this treatment to other cancers including RCC.

Based on the antigen specificity of the immune system and the safety profile of cancer vaccines, the effective immunotherapy would be an ideal adjuvant, following initial clinical responses to definitive therapy [10]. In 2010, Yang B conducted autologous cytokine induced killer cells combined with IL-2 for therapy of elderly patients with B-cell malignant lymphoma [11]. The results showed that no adverse reaction was observed in all above mentioned patients. The percentages of CD3⁺,CD3⁺CD8⁺ and CD3⁺CD56⁺ increased significantly (p < 0.05), and serum levels of β2-microglobulin and LDH were markedly decreased (p < 0.05) after autologous CIK cell transfusion. The lymphoma symptoms were relieved with quality of life obviously elevated (p < 0.01) in all patients. Complete remission was seen in 8 patients. In conclusion, autologous CIK cells combined with IL-2 is safe and effective for the therapy of elderly patients with B-cell malignant lymphoma. In 2009, Thomas Schwaab and colleagues made use of autologous dendritic Cell with IL-2 therapy in RCC Patients [12]. The results showed all patients received between two and five treatment cycles. Overall objective clinical response rate was 50% with three complete responses. Treatment-related changes in correlative immunologic end points were noted.

On the basis of above research reports, we propose a new combinatorial therapy approach to mobilize anti-tumor immunity against RCC. Our results indicate that vaccination of these patients with gmDCs-CIK is safe and efficient. We found a ORR (39%) and a CRR (12%) which compared favorably to the historical observations of ORR (16%) and CR (6%) for high-dose IL-2 or IL-2 plus IFN-α therapy [13–16]. In addition, Turnbull JD and his colleages had reported results of a clinical trial [17] of bevacizumab in treating mRCC showing an ORR of 9.5% which was not superior to ORR in our study. Moreover, data of DCR is superior to other related clinical research [18, 19]. For example, Kadono Y et al. had conducted a clinical trial of IFN-α in systemic treatment on 15 patients with mRCC enrolled from June 2005 through September 2008 [20] showing an ORR of 7% and a DCR of 27% which is lower than our DCR of 75%.

Clinical response of immunotherapy was evaluated by WHO and RESIST in a large number of clinical trial. However there is now ample evidence that these criteria do not apply to immunotherapy [21]. Immunotherapy induced tumor regressions have been well documented after initial progression and even after the appearance of new lesions, which are presumably caused by the infiltration of lymphocytes into tumours. For example, in some patients receiving ipilimumab, metastases may grow or new lesions may even develop before there is a decline in total tumor burden. These observations have led to the proposal of novel immune-related response criteria, as response evaluation according conventional response criteria (such as WHO and RECIST) can lead to unwanted early cessation of treatment owing to initial tumor growth [22]. These observations reflect the different dynamics of the immune response compared with the direct effects of cytotoxic drugs on cancer cells [23]. This also has important implications for the design and conduct of clinical trials, such as the planning of interim analyses.

Historically, cancer immune therapies have focused on stimulation of effector cells. In the present study, we observed no obvious difference between pre-vaccination and post-vaccination in Th2 but Th1 is significant higher than pre-vaccination (p = 0.003). Subsets of lymphocyte were evaluated in 11 patients with RCC treated with gmDCs-CIK. Result shows CD3⁺, CD4⁺, CD4⁺/CD8⁺,CD56⁺, CD4⁺CD25⁺doesn’t have significantly difference (P > 0.05) as compared with treatment before. Th cells are central to the development of an immune response by activating antigen-specific effector cells and recruiting cells of the innate immune system [24]. Two predominant Th cell subtypes exist, Th1 and Th2. Th1 cells, characterized by secretion of IFN-gamma and TNF-alpha, are primarily responsible for activating and regulating the development and persistence of CTL. In addition, Th1 cells activate antigen-presenting cells (APC) and induce limited production of the type of antibodies that can enhance the uptake of infected cells or tumor cells into APC. Th2 cells favor a predominantly humoral response. Th1 immune response is considered more effective than T helper 2 (Th2) for anti-tumor immunity. In this study, Th1 is significant higher than pre-vaccination by immunotherapy which indirectly proves that the immunological effect. Most data on lymphocyte subsets in malignant disease originate from melanoma or renal cell carcinoma (RCC) studies. There are several studies implying that the relative amount of CD3⁺, CD4⁺, CD8⁺, and CD56⁺ may be important and by reducing the tumor burden. However, only some of these studies imply that these changes can have an correlation on clinical outcome and prognosis [21]. Our results showed no correlation between recent clinical efficacy and metastatic sites from either bone or lung. This differed from results from other references for the difference of TNM staging of renal cancer, time of immune treatment, cycle of treatment, and time of testing of the peripheral blood lymphocyte subsets [25]. However, at present there is a lack of robust assays to monitor the anti-tumor immune response. Although there is an abundance of different assays that are being used to measure tumor antigen-specific T cell responses, these assays have not shown consistent results among trials, and none has been validated in prospective clinical trials.

In conclusion, genetically modified DCs in combination with CIK represent a novel immunotherapy approach for treating advanced RCC. gmDCs-CIK is safe and effective for RCC. We have revealed, for the first time, the relationship between cycle of treatment and the DCR; our study also has indicated that immunotherapy could improve the clinical efficacy of advanced renal cancer and increased frequency of immunotherapy could result in additional benefits. A larger scale clinical trial should be conducted to confirm the conclusion. Standardization of immunotherapy needs to be the focus of ongoing research.