**4. Vaccines**

However, the current 3-year overall survival rate is yet no more than 40% and a majority of patients will die because of the progressed disease [5]. As a consequence, new targets and therapies are needed to improve patient outcomes. The rapidly evolving field of immunooncology yields several novel immunotherapeutic agents. Currently, cancer vaccines, adoptive T-cell therapy, and immune checkpoint inhibitors (ICIs) are being investigated in advanced RCC and are producing durable responses and noteworthy overall survival improvement. This chapter mainly introduces the treatment landscape of immune therapeutics for RCC.

The immune system interacts intimately with tumors over the entire disease process. The complex crosstalk between the immune system and cancer cells determines the eventual outcome, either inhibiting or enhancing tumor development [6]. First, antigen-presenting cells (APCs), primarily dendritic cells (DCs), must encounter tumor-associated antigen (TAA), which can emerge via the altered protein structure caused by somatic mutations or differentially expressed proteins. The antigen expression pattern needs to be different from that on normal cells to avoid immune tolerance. APCs process TAA into peptide fragments, which then form a complex with major histocompatibility complex (MHC) class I and II molecules. The initial step of T-cell activation is the recognition of antigen presented on the MHC molecule of APCs by T-cell receptor (TCR). Full T-cell activation also requires a co-stimulatory

signal by the binding of CD28 on T cell to B7 ligands (CD80 and CD86) on APCs [7].

Multiple feedback mechanisms exert stimulatory or inhibitory effects on T cells, regulating immune function and preventing an excessive immune response. These mechanisms include immune checkpoint molecules on the surface of T cells and other immune cells such as regulatory T (Treg) cells and myeloid-derived suppressor cells (MDSCs) [8]. Tumor cells can take advantage of these mechanisms to prevent a potential anticancer immune response. RCC usually presents prominent immune cell infiltration, including T cells, natural killer (NK) cells, DCs, and macrophages. During early stages, malignant cells can be poor stimulators and become resistant to the innate immune response. Later, progressively growing tumors impair the adaptive immune response by blocking T-cell signal transduction and function [9]. An increased understanding of these processes has enabled the development of immunotherapy for cancer management.

Immunotherapy is defined as excluding cancer by activating the autoimmune response against the tumor rather than by attacking the tumor directly. Immunotherapy can induce long-lasting anticancer responses owing to the generation of antigen-specific immune memory, either through memory T-cells or antibodies. Several crucial steps are needed to mount an initial effective immune response against tumors [10]. Immune checkpoint blockade disrupts negative immune regulations to enhance immune system activity and boost antitumor immune response. Other immunomodulatory therapies such as cytokine therapy and vaccines potentiate co-stimulatory pathways or stimulate the innate immunity or interact with the immune suppressive tumor microenvironment. The past decade has witnessed the emergence of immunotherapy as an exciting treatment option for different malignancies, including

RCC. The following sections discuss these in more detail (**Figure 1**).

**2. Immunotherapy**

44 Evolving Trends in Kidney Cancer

Studies on vaccine therapies in mRCC are still ongoing. They mainly focus on the treatment of primary tumors rather than prevention. Tumor vaccines have been designed to enhance the ability of the immune system to recognize tumor antigens, improve immune microenvironment, and trigger strong specific antitumor cell immunity. Currently, clinical trials evaluating various vaccines have been conducted, although none has demonstrated an improvement in survival thus far. In the future, vaccination approaches will probably be further tailored to the patient's mutanome and tumor-associated antigen profile, with the goal of individualizing treatments and, thus, maximizing the potential benefits [14–16].

combination with IFN-α, IL-2, or sunitinib as a first-line mRCC therapy did not lead to a significant difference in OS when compared to the arm without MVA-5 T4 (median 20.1 months MVA-5 T4 versus 19.2 months placebo, p = 0.55). The adverse events' profile was also similar

Immunotherapy for Renal Cell Carcinoma http://dx.doi.org/10.5772/intechopen.77377 47

Principally, autologous tumor cell lysate vaccine active APCs, such as dendritic cells, which stimulate a cytotoxic T lymphocyte response toward tumor-associated antigens, leading to tumor cell destruction [26–28]. Adjuvant treatment with autologous vaccination Reniale (Liponova AG, Hannover, Germany) improved OS in pT3 RCC patients (10-year OS rates: 53.6% in vaccine group versus 36.2% in control group; p = 0.022) in a phase III study [29]. Additional current studies on nonprotein antigens have been limited. There are other ongoing trials involving the DC-based vaccines. Some of the promising ones involve the transduction of a fusion gene construct of GM-CSF and carbonic anhydrase IX into autologous DCs (NCT01826877), DC/RCC fusion cells in combination with pidilizumab (a PD-1 antibody) (NCT01441765), and DCs in combination with cytokine-induced killer cells

Peptides derived from tumor-associated antigens are presented via MHC I and II epitopes to

the peptide presented by MHC requires further co-stimulatory signals, resulting in the activation of downstream pathways and secretion of cytotoxic molecules, such as granzyme and perforin [31]. Regulatory mechanisms exist to weaken or inhibit immune response, avoiding excessive autoimmune response. These breaks in the immune system are often referred to as "immune checkpoints," including PD-1/PD-L1, CTLA4/CD80, and so on. Immune checkpoint proteins on CTLs cut off co-stimulatory signals after ligand binding and give rise to T-cell anergy and immune suppression. However, immune checkpoint proteins may become dysregulated under tumor settings, typically via an overexpression of inhibitory ligands and receptors [32]. Blocking these immune checkpoint proteins could improve the capability of

Over the past decade, immune checkpoint inhibition (ICI) has become a major focus of research given its durable response rates and promising survival benefits in various malignancies. Current ICIs include the cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) antibodies (ipilimumab and tremelimumab), the programmed cell death protein 1 (PD-1) antibodies (nivolumab, pembrolizumab, and pidilizumab), and the programmed cell death protein ligand 1 (PD-L1) antibodies (atezolizumab, BMS-936559, durvalumab, and avelumab) [35] (**Figure 2**). Multiple clinical trials studying the efficacy of these agents on mRCC are being conducted (**Table 1**), among which nivolumab is the only agent approved for the treatment of

T cells, respectively [30]. The binding of the T-cell receptor (TCR) to

between the treatment arms.

(NCT00862303).

stimulate CD8<sup>+</sup>

**4.4. Autologous tumor cell lysate (Reniale)**

**5. Immune checkpoint inhibitors**

and CD4+

mRCC by USFDA in 2015 [36].

CTL to mount and maintain an effective T-cell response [32–34].

#### **4.1. AGS-003**

AGS-003 is a dendritic cell immunotherapeutic vaccine constructed from autologous blood dendritic cells and generated through the electroporation of tumor-derived RNA and CD40 ligands (CD40L) RNA into host immune cells [17–19]. The tumor RNA-loaded mature dendritic cells present patient tumor-specific antigens in T-cells via MHC I. Meanwhile, the upregulated CD40L promotes the recruitment of CD8<sup>+</sup> T-cell through the regional production of IL-12. A phase II study on 21 mRCC patients were treated by a combination therapy of AGS-003 with 1 cycle of sunitinib (4 weeks on, 2 weeks off), followed by AGS-003 immunotherapy until tumor progression or the end of the study. The median progression-free survival (PFS) and overall survival (OS) were 11.2 months and 30.2 months, respectively. Remarkably, OS was more than 5 years in 5 patients (24%), with 2 patients achieving durable responses for more than 5 years. Of 21 patients, 13 (62%) achieved a clinical benefit (9 with a partial response and 4 with stable disease). Treatment with AGS-003 was well tolerated, with injection site reactions as the primary adverse event (AE). Based on these promising results, a randomized multicenter phase III ADAPT trial is currently under way, to determine whether there is an overall survival benefit between AGS-003 and sunitinib in comparison to sunitinib alone in mRCC patients undergoing de-bulking nephrectomy (NCT01582672).

#### **4.2. IMA901**

IMA901 is a therapeutic vaccine consisting of nine different HLA class I-binding tumorassociated peptides and one HLA class II-binding tumor-associated peptide. A phase II trial investigating the addition of cyclophosphamide (which reduces the T regulatory cells) to IMA901 showed that pretreatment with cyclophosphamide prolonged the survival of RCC patients compared with IMA901 therapy alone [20]. The majority of adverse events reported were local injection site reactions. A phase III trial comparing sunitinib with or without this vaccine for mRCC was recently completed. Unfortunately, the OS did not differ significantly between the 2 groups [21].

#### **4.3. Modified vaccinia Ankara (MVA-5 T4; TroVax)**

MVA-5 T4 was created to stimulate the immune system to destroy cells expressing 5 T4 antigen. The 5 T4 oncofetal antigen is rarely detected in normal adult tissues but is over-expressed in kidney cancer [22–24]. A randomized, double-blind phase III study (TRIST trial) assessed OS and safety in patients with mRCC [25]. Patients were randomized to MVA-5 T4 (n = 365) or placebo (n = 368) in combination with IL-2, IFN-α, or sunitinib. Unfortunately, MVA-5 T4 in combination with IFN-α, IL-2, or sunitinib as a first-line mRCC therapy did not lead to a significant difference in OS when compared to the arm without MVA-5 T4 (median 20.1 months MVA-5 T4 versus 19.2 months placebo, p = 0.55). The adverse events' profile was also similar between the treatment arms.

#### **4.4. Autologous tumor cell lysate (Reniale)**

ability of the immune system to recognize tumor antigens, improve immune microenvironment, and trigger strong specific antitumor cell immunity. Currently, clinical trials evaluating various vaccines have been conducted, although none has demonstrated an improvement in survival thus far. In the future, vaccination approaches will probably be further tailored to the patient's mutanome and tumor-associated antigen profile, with the goal of individualizing treatments

AGS-003 is a dendritic cell immunotherapeutic vaccine constructed from autologous blood dendritic cells and generated through the electroporation of tumor-derived RNA and CD40 ligands (CD40L) RNA into host immune cells [17–19]. The tumor RNA-loaded mature dendritic cells present patient tumor-specific antigens in T-cells via MHC I. Meanwhile, the

of IL-12. A phase II study on 21 mRCC patients were treated by a combination therapy of AGS-003 with 1 cycle of sunitinib (4 weeks on, 2 weeks off), followed by AGS-003 immunotherapy until tumor progression or the end of the study. The median progression-free survival (PFS) and overall survival (OS) were 11.2 months and 30.2 months, respectively. Remarkably, OS was more than 5 years in 5 patients (24%), with 2 patients achieving durable responses for more than 5 years. Of 21 patients, 13 (62%) achieved a clinical benefit (9 with a partial response and 4 with stable disease). Treatment with AGS-003 was well tolerated, with injection site reactions as the primary adverse event (AE). Based on these promising results, a randomized multicenter phase III ADAPT trial is currently under way, to determine whether there is an overall survival benefit between AGS-003 and sunitinib in comparison to sunitinib

IMA901 is a therapeutic vaccine consisting of nine different HLA class I-binding tumorassociated peptides and one HLA class II-binding tumor-associated peptide. A phase II trial investigating the addition of cyclophosphamide (which reduces the T regulatory cells) to IMA901 showed that pretreatment with cyclophosphamide prolonged the survival of RCC patients compared with IMA901 therapy alone [20]. The majority of adverse events reported were local injection site reactions. A phase III trial comparing sunitinib with or without this vaccine for mRCC was recently completed. Unfortunately, the OS did not differ significantly

MVA-5 T4 was created to stimulate the immune system to destroy cells expressing 5 T4 antigen. The 5 T4 oncofetal antigen is rarely detected in normal adult tissues but is over-expressed in kidney cancer [22–24]. A randomized, double-blind phase III study (TRIST trial) assessed OS and safety in patients with mRCC [25]. Patients were randomized to MVA-5 T4 (n = 365) or placebo (n = 368) in combination with IL-2, IFN-α, or sunitinib. Unfortunately, MVA-5 T4 in

alone in mRCC patients undergoing de-bulking nephrectomy (NCT01582672).

T-cell through the regional production

and, thus, maximizing the potential benefits [14–16].

upregulated CD40L promotes the recruitment of CD8<sup>+</sup>

**4.1. AGS-003**

46 Evolving Trends in Kidney Cancer

**4.2. IMA901**

between the 2 groups [21].

**4.3. Modified vaccinia Ankara (MVA-5 T4; TroVax)**

Principally, autologous tumor cell lysate vaccine active APCs, such as dendritic cells, which stimulate a cytotoxic T lymphocyte response toward tumor-associated antigens, leading to tumor cell destruction [26–28]. Adjuvant treatment with autologous vaccination Reniale (Liponova AG, Hannover, Germany) improved OS in pT3 RCC patients (10-year OS rates: 53.6% in vaccine group versus 36.2% in control group; p = 0.022) in a phase III study [29]. Additional current studies on nonprotein antigens have been limited. There are other ongoing trials involving the DC-based vaccines. Some of the promising ones involve the transduction of a fusion gene construct of GM-CSF and carbonic anhydrase IX into autologous DCs (NCT01826877), DC/RCC fusion cells in combination with pidilizumab (a PD-1 antibody) (NCT01441765), and DCs in combination with cytokine-induced killer cells (NCT00862303).
