**9. Therapy response and predictive biomarkers**

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

RCC, renal cell carcinoma; TKI, tyrosine kinase inhibitor; VEGF, vascular endothelial growth factor.

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

**Checkpoint inhibitor Targeted therapy Phase Population Identifier**

I Advanced RCC,

RCC

allowed

RCC

RCC

RCC

RCC

RCC

RCC

prior therapy allowed

prior cytokine therapy allowed

advanced clear cell

RCC, prior therapy

advanced clear cell

advanced clear cell

RCC treated with failure of at least one prior therapy

treated with at least one prior VEGF TKI

advanced clear cell

advanced clear cell

advanced clear cell

advanced clear cell

NCT01472081 (CheckMate

016)

NCT01633970

NCT02210117

NCT02423954

NCT02014636

NCT02133742

NCT02348008

NCT02298959

NCT02493751

NCT02420821

NCT02684006

KEYNOTE-426)

NCT02853331 (MK-3475-426/

Nivolumab Sunitinib

56 Evolving Trends in Kidney Cancer

Pazopanib

Atezolizumab Bevacizumab Ib Untreated,

Nivolumab Bevacizumab Neoadjuvant pilot Metastatic clear cell

Nivolumab Temsirolimus Ib/II Metastatic RCC,

Pembrolizumab Pazopanib I/II Untreated,

Pembrolizumab Axitinib Ib Untreated,

Pembrolizumab Bevacizumab Ib/II Metastatic clear cell

Pembrolizumab Aflibercept I Metastatic RCC

Avelumab Axitinib Ib Untreated,

Atezolizumab Bevacizumab III Untreated,

Avelumab Axitinib III Untreated,

Pembrolizumab Axitinib III Untreated,

therapies.

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 predictive biomarkers of treatment response to optimize patient selection.

The evaluation of responses to immunotherapeutic agents represents a challenge in the clinic. Specific tumor response patterns with ICI treatment sometimes differ from those with chemotherapeutic and targeted agents. Due to immune-mediated mechanisms, tumor flare, which shows enlarged size of baseline lesions or increased total tumor burden, may occur before cellular immune responses have a chance to affect the actual tumor size [103]. Additionally, transient immune cell infiltration at the tumor site may boost the appearance of tumor growth [103, 104]. Therefore, tumor flare can confuse tumor response interpretation by appearing as disease progression, hence the term pseudoprogression, and may result in inappropriately switching therapy before ongoing clinical benefits manifest on imaging [105]. While pseudoprogression is relatively uncommon (occurring in <10% of patients) versus true progression, it sometimes presents a challenge for patients and for clinicians in determining when to stop and/or switch therapy [105]. Recently updated guidelines for the use of modified RECIST (iRECIST) in trials of immunotherapies were published in an effort to standardize and validate these criteria and harmonize the interpretation of the results [106].

Preclinical research has demonstrated the role of VEGF in suppressing tumor immune responses—an attractive strategy to combine with ICIs [117–119]. This successful synergy has been confirmed in phase 1 and 2 studies with axitinib-pembrolizumab [84], axitinib-avelumab [120], lenvatinib-pembrolizumab [121], and bevacizumab-atezolizumab [122, 123]. The ORR ranged between 32% and 67%, and AEs were manageable in all these studies, in contrast to studies in other combinations as TKIs (pazopanib/sunitinib) plus immunotherapy, which did not move forward because of unacceptable toxicity [83, 124, 125]. Although preliminary, the abovementioned results are encouraging and have led to larger, confirmatory, phase 3 trials,

Immunotherapy for Renal Cell Carcinoma http://dx.doi.org/10.5772/intechopen.77377 59

In addition, different novel immunotherapies beyond ICIs are being investigated, including

Adoptive T-cell transfer therapy refers to the autologous or allogeneic infusion of T-cells. One such therapy involves the generation and infusion of chimeric antigen receptor (CAR) T-cells—T cells that have been genetically modified to express a receptor specific to tumor epitopes independent of HLA. The promising efficacy of anti-CD19 CAR T cells in hematological malignancies has inspired further investigations in solid tumors [126]. One of the key aspects of designing effective CAR T cells is finding a tumor-associated antigen that is uniformly expressed in tumor cells but not in the normal tissue. Carbonic anhydrase 9 (CAIX) is an enzyme that is overexpressed in clear-cell RCC but minimally expressed in normal tissue [127]. Early efforts in using CAIX as a tumor-associated antigen for CAR resulted in liver enzyme elevations that limited its use, likely owing to the therapy also targeting CAIX expressed in the liver bile duct epithelium [128]. Cor H.J. Lamers and his colleagues gave patients a CAIX monoclonal antibody before infusion of CAR T cells to reduce this off-target toxicity [129]. However, in the study, no clinical

responses were observed, and the efficacy of CAIX CAR T cells is yet to be proven.

show that therapy is well tolerated and might have activity against RCC [132].

and in combination with atezolizumab in phase I/II trials in RCC (NCT02386111).

Another form of adoptive immune cell therapy tested in RCC is autologous cytokine-induced killer (CIK) cell immunotherapy. CIK cells are created in vitro by harvesting peripheral mononuclear cells in the blood using an anti-CD3 antibody. The resulting phenotype by IL-1, IFNγ, and IL-2 shares features of effector T-cells and natural killer cells [130]. A phase II trial randomly assigned 148 patients with mRCC to CIK cell immunotherapy or IL-2 combined with IFNα [131]. PFS and OS at 3 years in the CIK cell therapy arm were 18% and 61%, respectively, compared with 12% and 23% in the IL-2 plus IFNα arm (p = 0.031 and p < 0.001, respectively). This therapy is being further investigated in conjunction with DC vaccines and early results

Stimulatory molecules expressed on immune cells can also be targeted with agonist antibodies. CD137 is a co-stimulatory molecule for T-cells that increases T-cell effector activity and survival. Its use in combination with anti-DR5 and anti-CD40 antibodies in mouse models of RCC has shown to improve survival compared with control mice (p < 0.001) [133]. The CD137 agonist PF-05082566 is currently being tested in combination with pembrolizumab in a phase I trial of advanced solid tumors, including RCC (NCT02179918). Varlilumab is an agonist antibody targeting CD27, another co-stimulatory molecule for T-cell activation. In a phase I trial in solid tumors, including 11 patients with RCC, of the six evaluable RCC patients, two had stable diseases [134]. This antibody is currently being studied in combination with sunitinib

which are now actively accruing patients.

adoptive T-cell therapy and T-cell agonists.

Response to ICI has been associated with specific intrinsic and extrinsic properties of tumors or of the host that have been recently classified as the elements of the cancer-immune set point [107]. Intrinsic properties reflect the degree of tumor foreignness [108], linked to the mutational burden and the presence of neoantigens that can be recognized by the immune system, as shown in NSCLC and melanoma [109, 110]. Foreignness of RCC might vary by molecular subtype and a higher number of mutations [111]. In addition, the general individual immune status, mirrored by the levels of circulating lymphocytes and the neutrophil to lymphocyte ratio (NLR), the increase of the C reactive protein, the erythrocyte sedimentation rate PD-L1 expression (although controversial), and LDH were shown to influence the response to ICI.

In addition to the intrinsic properties of the tumors, extrinsic factors, such as exposure to sunlight and to cigarette smoke, the presence of viral infections, and the composition of the gut microbiota, were classified as elements of the cancer-immune set point [107]. The exposure to sunlight and cigarette smoke was relevant for melanoma and NSCLC, respectively, while the presence of viral infections might impact the response to ICI in human papilloma virus positive tumors and Epstein-Barr virus related tumors. Preclinical evidence showed that several bacteroides and bifidobacterium species influenced the efficacy of ICI with anti-CTLA-4 and anti-PD-L1 mAb in mice [112–114]. The role of the gut microbiota in patients with renal cancer treated with ICB requires further investigations.

Taken together, these data suggest that multiple parameters should be taken into account to identify ideal candidates for immunotherapy in RCC. The genomic landscape likely has a role in determining the putative immunogenicity of the tumor [115]; TIL, PD-L1 expression, and immune gene signatures could detect tumors with an inflamed phenotype, which have higher chances of response to ICB [107, 116].
