*5.2.2. BMS-936559*

BMS-936559 (MDX-1105) is a fully human monoclonal antibody with high affinity to PD-L1 and blocks the binding of PD-L1 to both PD-1 and B7.1. In a phase I trial of evaluating BMS-936559 in 207 patients with different advanced cancer types, 17 patients had mRCC. The study showed that 2 of 17 RCC patients had an objective response with response durations for 4 and 17 months, respectively [59].

#### *5.2.3. Avelumab*

Avelumab (MSB0010718C) is a fully human IgG1 monoclonal antibody against PD-L1 and inhibits PD-1-PD-L1 interactions. It also has a native Fc region that could induce antibody-dependent cell-mediated cytotoxicity (ADCC). In a phase Ib, open-label expansion study, avelumab was used in patients with advanced solid tumors and showed an acceptable safety profile [60]. Two ongoing trials evaluate avelumab in combination with axitinib (NCT02493751, NCT02684006).

#### *5.2.4. Durvalumab*

Durvalumab (MEDI4736) is another human anti-PD-L1 IgG1 monoclonal antibody. It blocks PD-L1 binding to PD-1 and CD80, with no binding to PD-L2. ADCC and complement-dependent cytotoxicities are removed by an engineered triple mutation in the Fc domain. A Phase 1/2, multicenter, open-label study which evaluated the safety and clinical activity of the drug in patients with multiple solid tumor types such as non-small cell lung cancer noted a very manageable safety profile [61]. There are ongoing trials evaluating durvalumab in combination with other drugs, including tremelimumab (NCT01975831) and MEDI0680 (AMP-514) (a humanized IgG4 monoclonal antibody against PD-1) (NCT02118337) for patients with advanced malignancies including RCC.

#### **5.3. Anti-CTLA-4 antibodies**

In addition to the PD-1/PD-L1 checkpoint, CTLA-4, an immune checkpoint on the surface of cytotoxic T-cells, counteracts the action of the co-stimulatory receptor CD28 and plays a key role in the immune response. Both CTLA-4 and CD28 bind identical ligands CD80 and CD86 (called B7-1 and B7-2), but CTLA4 has a higher affinity for both ligands than CD28. Therefore, CTLA4 can antagonize CD28-ligand interactions by competing for ligand binding. In addition, the interaction of CTLA4 with CD80 or CD86 can lead to the endocytosis of these ligands from the APC surface into a CTLA4-expressing T-cell (a process called trans-endocytosis). The ligand removal impairs the stimulatory capacity of APCs by limiting CD28 signaling and thus inhibits T-cell responses [32, 62]. CTLA-4 antibodies were initially tested on colon adenocarcinoma and sarcoma in mouse models with noted tumor shrinkage [63]. These encouraging results led to the subsequent development of CTLA-4 antibodies, including ipilimumab and tremelimumab.

achieving a heightened antitumor effect [76]. This approach has demonstrated clinically effective synergy from nivolumab plus ipilimumab treatment in patients with advanced melanoma [77]. Several studies are ongoing in patients with mRCC on the combinations of ICIs with different targets, for example, anti-PD-1 or PD-L1 and anti-CTLA-4 antibodies [78, 79], allowing dual/multifaceted manipulation of immunosuppression. A combination of nivolumab and ipilimumab has acquired success in patients with treatment naïve or previously treated RCC (CheckMate 016 study) with an ORR of about 40% [80] these provided the rationale for a phase III trial comparing this combination with sunitinib in treatment-naïve

Immunotherapy for Renal Cell Carcinoma http://dx.doi.org/10.5772/intechopen.77377 55

Emerging evidence suggests that antiangiogenic therapies may have immune-modulatory effects such as the enhancement of cytotoxic T-cell trafficking and infiltration in addition to their known direct antiangiogenic effects, possibly potentiating the effectiveness of checkpoint inhibitors when administered concurrently [81]. Based on this rationale, several clinical studies are ongoing in patients with mRCC under the combinations of ICIs and VEGF pathway inhibitors (**Table 2**) [78, 79]. While a few of these combinations have produced unacceptable hepatic toxicity [82, 83], the use of the combinations of PD-1 pathway inhibitors with more selective inhibitors of the VEGF pathway (e.g., atezolizumab with bevacizumab, pembrolizumab with axitinib, or avelumab with axitinib) has proven to be more tolerable [55, 84–87]. Preliminary results from studies combining immune checkpoints and VEGF pathway inhibitors have shown encouraging clinical activity in terms of PFS and ORR [83–86]. In an ongoing phase Ib study of 52 treatment-naïve patients, pembrolizumab plus axitinib resulted in an ORR of 67%, including 2 complete responses and 33 PR; median PFS is not yet mature, with 7 patients of 11 enrolled in the dose-finding phase remaining progression-free at 11 months [84]. Smaller phase I studies evaluating avelumab plus axitinib and pembrolizumab plus pazopanib combination therapy reported ORRs of 83% (5 PRs of 6 treated patients) and 60% (6 of 10 patients; pazopanib 800 mg cohort), respectively [47, 85]. Atezolizumab plus bevacizumab combination therapy in 10 previously untreated patients with mRCC also resulted in clinical benefits (4 patients with PRs and 4 with stable disease) [86]. Confirmatory randomized phase III trials comparing sunitinib versus either atezolizumab with bevacizumab (NCT02420821), avelumab with axitinib (NCT02684006), or pembrolizumab with axitinib (NCT02853331) are ongoing. Preclinical data from an RCC mouse model showed that radiation enhanced the therapeutic effect of IL-2 immunotherapy on pulmonary metastases [88]. One explanation is that DCs are recruited to the irradiated site when radiotherapy is applied in few-fraction and high-dose manners [89]. Currently, a clinical trial evaluating the combination of radiation therapy with pembrolizumab for patients with recurrent or mRCC is ongoing (NCT02318771). Therefore, a number of combination strategies, such as PD-1/PD-L1 blockade, PD-1 antibody with other immunotherapeutic agents, PD-1 antibody with antiangiogenesis agents, and combination with radiotherapy, are currently in clinical trial research to determine whether there is a most favorable sequence of treatment and if combination strategy benefits mRCC patients. Results from recent clinical trials with immunotherapeutic agents suggest that immunotherapy in combination with other agents is capable of producing durable responses and significant overall survival improvement. Thus, in the future, immunotherapy, together with other treatments, will likely cause a paradigm shift in the clinical management of mRCC patients. However, the combination of immunotherapeutic agents does have considerable

patients (CheckMate 214, NCT02231749).

#### *5.3.1. Ipilimumab*

Ipilimumab, an anti-CTLA-4 IgG1 monoclonal antibody, received US FDA approval for the treatment of melanoma in 2011 [64, 65]. It has been investigated as monotherapy plus nivolumab in metastatic melanoma, with the combination treatment being more effective albeit accompanied with significantly more toxicity [66]. Currently, ipilimumab is being investigated in mRCC with the combination of nivolumab. In a phase II study of ipilimumab in patients with mRCC, 1 of 21 patients had a partial response in the lower dose group (3 mg/ kg followed by 1 mg/kg every 3 weeks). A total of 5 of 40 patients had partial responses at the higher dose (3 mg/kg every 3 weeks). AEs were highly significant and associated with tumor regression [67]. Ipilimumab has also been investigated in another phase II trial in mRCC; however, just 12% of patients achieved a partial response, with a substantial amount of toxicities [67]. Further phase III trials investigating ipilimumab alone (NCT00057889) and in combination with other drugs have not yet been studied (NCT02231749, NCT02381314).

#### *5.3.2. Tremelimumab*

Tremelimumab is another anti-CTLA-4 antibody that is actively being investigated in mRCC. Unlike ipilimumab, it is an IgG2 antibody. It is currently being evaluated with durvalumab in the treatment of patients with mRCC (NCT01975831).

#### **5.4. Anti-LAG-3 antibodies**

Lymphocyte activation gene 3 (LAG-3) is expressed on activated T cells and Treg-cells [68]. Upon binding to the MHC class II on APCs, LAG-3 induces an inhibitory signal in T-cells [69], whereas LAG-3 enhances the suppressive function of Treg-cells [70, 71]. Co-expression of LAG-3 and PD-1 is a marker of exhausted T cells and, therefore, the blockade of both receptors confers additive therapeutic activity in preclinical models of chronic infection and cancer [72–74]. In a phase I study, a soluble LAG-3-Ig fusion protein (IMP321), which was designed to stimulate MHC class II-driven DC activation, has been evaluated in patients with advanced RCC. IMP321 induced CD8 T-cell activation in patients and disease stabilization with the absence of toxicity [75]. Currently, a blocking mAb targeting LAG-3 is being tested in the clinic (NCT01968109).

## **6. Combined therapy**

Preclinical studies point out that the dual blockade of PD-1 and CTLA-4 reduced regulatory Treg cell infiltration and increased effector T-cell infiltration and interferon-γ production, achieving a heightened antitumor effect [76]. This approach has demonstrated clinically effective synergy from nivolumab plus ipilimumab treatment in patients with advanced melanoma [77]. Several studies are ongoing in patients with mRCC on the combinations of ICIs with different targets, for example, anti-PD-1 or PD-L1 and anti-CTLA-4 antibodies [78, 79], allowing dual/multifaceted manipulation of immunosuppression. A combination of nivolumab and ipilimumab has acquired success in patients with treatment naïve or previously treated RCC (CheckMate 016 study) with an ORR of about 40% [80] these provided the rationale for a phase III trial comparing this combination with sunitinib in treatment-naïve patients (CheckMate 214, NCT02231749).

the interaction of CTLA4 with CD80 or CD86 can lead to the endocytosis of these ligands from the APC surface into a CTLA4-expressing T-cell (a process called trans-endocytosis). The ligand removal impairs the stimulatory capacity of APCs by limiting CD28 signaling and thus inhibits T-cell responses [32, 62]. CTLA-4 antibodies were initially tested on colon adenocarcinoma and sarcoma in mouse models with noted tumor shrinkage [63]. These encouraging results led to the subsequent development of CTLA-4 antibodies, including ipilimumab and tremelimumab.

Ipilimumab, an anti-CTLA-4 IgG1 monoclonal antibody, received US FDA approval for the treatment of melanoma in 2011 [64, 65]. It has been investigated as monotherapy plus nivolumab in metastatic melanoma, with the combination treatment being more effective albeit accompanied with significantly more toxicity [66]. Currently, ipilimumab is being investigated in mRCC with the combination of nivolumab. In a phase II study of ipilimumab in patients with mRCC, 1 of 21 patients had a partial response in the lower dose group (3 mg/ kg followed by 1 mg/kg every 3 weeks). A total of 5 of 40 patients had partial responses at the higher dose (3 mg/kg every 3 weeks). AEs were highly significant and associated with tumor regression [67]. Ipilimumab has also been investigated in another phase II trial in mRCC; however, just 12% of patients achieved a partial response, with a substantial amount of toxicities [67]. Further phase III trials investigating ipilimumab alone (NCT00057889) and in combi-

nation with other drugs have not yet been studied (NCT02231749, NCT02381314).

valumab in the treatment of patients with mRCC (NCT01975831).

Tremelimumab is another anti-CTLA-4 antibody that is actively being investigated in mRCC. Unlike ipilimumab, it is an IgG2 antibody. It is currently being evaluated with dur-

Lymphocyte activation gene 3 (LAG-3) is expressed on activated T cells and Treg-cells [68]. Upon binding to the MHC class II on APCs, LAG-3 induces an inhibitory signal in T-cells [69], whereas LAG-3 enhances the suppressive function of Treg-cells [70, 71]. Co-expression of LAG-3 and PD-1 is a marker of exhausted T cells and, therefore, the blockade of both receptors confers additive therapeutic activity in preclinical models of chronic infection and cancer [72–74]. In a phase I study, a soluble LAG-3-Ig fusion protein (IMP321), which was designed to stimulate MHC class II-driven DC activation, has been evaluated in patients with advanced RCC. IMP321 induced CD8 T-cell activation in patients and disease stabilization with the absence of toxicity [75]. Currently, a blocking mAb targeting LAG-3 is being tested in the clinic (NCT01968109).

Preclinical studies point out that the dual blockade of PD-1 and CTLA-4 reduced regulatory Treg cell infiltration and increased effector T-cell infiltration and interferon-γ production,

*5.3.1. Ipilimumab*

54 Evolving Trends in Kidney Cancer

*5.3.2. Tremelimumab*

**5.4. Anti-LAG-3 antibodies**

**6. Combined therapy**

Emerging evidence suggests that antiangiogenic therapies may have immune-modulatory effects such as the enhancement of cytotoxic T-cell trafficking and infiltration in addition to their known direct antiangiogenic effects, possibly potentiating the effectiveness of checkpoint inhibitors when administered concurrently [81]. Based on this rationale, several clinical studies are ongoing in patients with mRCC under the combinations of ICIs and VEGF pathway inhibitors (**Table 2**) [78, 79]. While a few of these combinations have produced unacceptable hepatic toxicity [82, 83], the use of the combinations of PD-1 pathway inhibitors with more selective inhibitors of the VEGF pathway (e.g., atezolizumab with bevacizumab, pembrolizumab with axitinib, or avelumab with axitinib) has proven to be more tolerable [55, 84–87]. Preliminary results from studies combining immune checkpoints and VEGF pathway inhibitors have shown encouraging clinical activity in terms of PFS and ORR [83–86]. In an ongoing phase Ib study of 52 treatment-naïve patients, pembrolizumab plus axitinib resulted in an ORR of 67%, including 2 complete responses and 33 PR; median PFS is not yet mature, with 7 patients of 11 enrolled in the dose-finding phase remaining progression-free at 11 months [84]. Smaller phase I studies evaluating avelumab plus axitinib and pembrolizumab plus pazopanib combination therapy reported ORRs of 83% (5 PRs of 6 treated patients) and 60% (6 of 10 patients; pazopanib 800 mg cohort), respectively [47, 85]. Atezolizumab plus bevacizumab combination therapy in 10 previously untreated patients with mRCC also resulted in clinical benefits (4 patients with PRs and 4 with stable disease) [86]. Confirmatory randomized phase III trials comparing sunitinib versus either atezolizumab with bevacizumab (NCT02420821), avelumab with axitinib (NCT02684006), or pembrolizumab with axitinib (NCT02853331) are ongoing. Preclinical data from an RCC mouse model showed that radiation enhanced the therapeutic effect of IL-2 immunotherapy on pulmonary metastases [88]. One explanation is that DCs are recruited to the irradiated site when radiotherapy is applied in few-fraction and high-dose manners [89]. Currently, a clinical trial evaluating the combination of radiation therapy with pembrolizumab for patients with recurrent or mRCC is ongoing (NCT02318771).

Therefore, a number of combination strategies, such as PD-1/PD-L1 blockade, PD-1 antibody with other immunotherapeutic agents, PD-1 antibody with antiangiogenesis agents, and combination with radiotherapy, are currently in clinical trial research to determine whether there is a most favorable sequence of treatment and if combination strategy benefits mRCC patients. Results from recent clinical trials with immunotherapeutic agents suggest that immunotherapy in combination with other agents is capable of producing durable responses and significant overall survival improvement. Thus, in the future, immunotherapy, together with other treatments, will likely cause a paradigm shift in the clinical management of mRCC patients. However, the combination of immunotherapeutic agents does have considerable


**7. Adjuvant and neoadjuvant immunotherapy**

in the adjuvant or neoadjuvant setting of surgically managed patients.

evaluating ICIs as a single agent or in combination in patients with nccRCC.

predictive biomarkers of treatment response to optimize patient selection.

The use of immunotherapies for RCC provides evidence that immune-based treatments can drastically improve survival or antitumor effects for patients with advanced RCC. However, only certain patients obtain clinic benefit as a durable response, so we need to identify reliable

**9. Therapy response and predictive biomarkers**

**8. Non-clear cell RCC (nccRCC)**

With the promising outcome of immunotherapy in mRCC, it is reasonable to explore whether immunotherapy works in the non-metastatic adjuvant setting. Noteworthy, spontaneous antitumor immune infiltration was shown to be higher in primary tumors with respect to matched metastases [92], suggesting that the administration of immunotherapy in the early setting might be more effective than in the advanced setting. However, trials of adjuvant therapy involving tumor cell vaccination, IFN-α, or HD IL-2 have not shown survival benefits [93]. Trials studying the role of checkpoint inhibition (anti PD-1/PD-L1 agents) are proceeding, and the results are eagerly awaited. Studies are also under way to determine the feasibility of ICIs as neoadjuvant (nivolumab, NCT02575222, NCT02595918; durvalumab with or without tremelimumab, NCT02762006) or adjuvant therapy (nivolumab; NCT02595944, NCT02388906, NCT02743494, NCT02632409; pembrolizumab, NCT02362594, NCT02504372; atezolizumab, NCT02450331, NCT02927301, NCT02912559, NCT02486718). We believe that a big movement in RCC management will occur if we can find a way to increase survival rates

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Non-clear cell histology constitutes 20–25% of RCCs [94, 95]. However, this group is heterogeneous, and individually each subtype is relatively rare and thus difficult to study in large prospective trials. nccRCC includes papillary, chromophobe, sarcomatoid, collecting duct, medullary, and various hereditary forms, among which papillary is the most common subtype [94]. Patients with metastatic nccRCC have generally proven to be less responsiveness to the drugs shown to be active in ccRCC [96]. Although some patients with nccRCC may obtain some benefit from VEGF-targeting TKIs, retrospective studies have generally suggested that these agents have inferior efficacy compared with what would be expected in patients with ccRCC [97]. This was also true in the previous era of immunotherapy HD IL-2. Although included in some of the large trials of HD IL-2, patients with nccRCC rarely experienced clinical benefits [95, 98, 99]. Treatment with IFN-α has also showed limited efficacy in patients with non-clear cell histology [95]. No prospective data currently exist to characterize the response of patients with nccRCC to ICIs, though several case reports have been published identifying single responses across various histologies [100–102]. Several ongoing studies are

**Table 2.** Ongoing immune checkpoint inhibitor and targeted therapy combinational trials in RCC.

toxicities such as gastrointestinal and hepatic toxicities, and careful patient selection must be guaranteed [90, 91]. Therefore, much more studies must be taken to define the role of combination treatment with immunotherapy agents in mRCC. Moreover, further studies are warranted to identify biomarkers that reliably predict the treatment benefit from these new therapies.
