*3.1.1 Adjuvant treatment*

Post resection, numerous adjuvant therapies were undertaken in the hopes of enhancing survival, but none of them was found successful. Systemic treatment has relied heavily on sorafenib over the previous decade, making it the only medicine approved for first-line treatment since 2017. Currently, the approval of lenvatinib has been accepted in the practice of first-line setting [17]. T lymphocytes that have been grown ex vivo with cytokines make up CIK cells. In an open-label, phase-3 trial involving 230 patients (associated with HCC) who experienced surgical resection, patients who got CIK lived 44 months longer than those who received placebo (HR, 0.63; 95% CI 0.43–0.94; p = 0.010). However, despite these recent advancements, no adjuvant therapy has consistently proven effective.

### *3.1.2 Neoadjuvant therapy*

Neoadjuvant therapy is a treatment strategy applied prior to the primary cancer treatment to enhance the rate of success for the primary treatment. In neoadjuvant therapy, ICIs can take advantage of the elevated levels of tumor antigens present in the primary tumor to enhance the proliferative potential of tumor-specific T lymphocyte clones already existing in the TME [18]. Mice administered neoadjuvant Tregs level was reduced due to diphtheria toxin fragments. While anti-CD25 lived considerably longer (250 days) than control mice (100 days) in preclinical models of triplenegative breast cancer [19]. A limited time interval between the first administration of neoadjuvant immunotherapy and primary tumor excision was found essential for

maximum efficacy in a second trial, whereas a greater time interval abolished therapeutic efficacy in the neoadjuvant context. The viability of neoadjuvant cabozantinib with nivolumab in HCC was investigated in a single-arm phase 1b study [18]. The trial included 15 unresectable patients, 12 of whom had successful margin-negative resection after neoadjuvant cabozantinib and nivolumab therapy. Furthermore, responders showed enrichment of CD138+ plasma cells and a specific spatial rearrangement of B cells, with B cells in close proximity to other B cells, indicating that this combination modulated the TIME. These findings point to the need for a B-cell orchestration of antitumor immune responses. Immunotherapy is also being researched as a neoadjuvant treatment for liver transplantation. In HCC patients that meet the Milan criteria, the combination of lenvatinib and pembrolizumab is being tested in PLENTY202001 before liver transplantation. The usage of ICIs in the transplant scenario poses considerable safety concerns, as it can result in allograft rejection, which can be deadly [20]. As a result, solid organ patients are routinely excluded from clinical trials employing ICIs. The PLENTY202001 is an outlier in this regard, as it will collect extremely valuable safety data.

#### **3.2 Intermediate HCC immunotherapy**

TACE is the gold standard of therapy for intermediate-stage BCLC-HCC (B). This immunotherapy significantly improves OS [21]. In addition, TACE seems to influence the immunological response of tumors [22–24]. TACE can improve both the antitumor immune response and the pro-inflammatory tumor response by lowering Tregs and fatigued effector T-cells in the tumor core [23]. HCC patients (n = 32) who were not eligible for liver surgical resection or transplantation were evaluated for the efficacy and safety of tremelimumab (anti-CTLA-4) with ablation [25]. Tremelimumab was given to patients every 4 weeks for six doses. They had TACE (subtotal radiofrequency ablation) on day 36. Five of the 19 evaluable patients had an established partial response, and the median OS was 19.4 months. Six-week tumor biopsies revealed an increase in CD8+ T cells in those individuals who had a therapeutic benefit. Hence, the combination of locoregional plus immunotherapy for HCC at the intermediate stage is mechanistically justified. Because it enrolled patients with unresectable HCC. Furthermore, The IMbrave 150 trial revealed information regarding HCC-associated patients at an intermediate stage [8]. The ABC-HCC study proposes a novel type of primary endpoint called timeto-failure of treatment strategy, which assesses the time until the investigator discontinues either treatment strategy (systemic therapy or TACE) due to failure [26].

## **3.3 Immunotherapy for advanced-stage HCC**

Immunotherapy has been shown to be effective in the treatment of advanced HCC. ICIs, particularly those that target PD-1 or PD-L1, are the most commonly used drugs. They've been studied in big clinical studies both individually and in combination, and they have now become an important aspect of HCC treatment. Furthermore, new immunotherapies, including adoptive cell therapy with considerable improvement in ICI's therapeutic efficacy against HCC.

#### *3.3.1 Monotherapies with ICIs*

A monoclonal antibody, *i.e.,* nivolumab, targeting PD-1, was originally investigated in HCC in phase I/II CheckMate 040 investigation, which comprised 262 HCC

#### *Emerging Immunotherapy: Liver Cancer Microenvironment for Treatment DOI: http://dx.doi.org/10.5772/intechopen.106021*

patients with a previous history of sorafenib treatment. Nivolumab had a median response length of 73.87 weeks (95% confidence interval (CI) 6–24) and an ORR of 14 percent by RECIST 1.1 (18% by mRECIST) [27]. The study found a median OS of 15.6 months and a safety profile that was similar to prior nivolumab trials. As a result, the FDA granted nivolumab expedited approval for patients with advancedstage HCC who had previously received sorafenib treatment. In the CheckMate 459 research, nivolumab was compared with sorafenib as a first-line treatment in patients with advanced HCC who had not previously undergone systemic treatment.

In HCC patients (with a previous history of sorafenib treatment) after intolerable toxicity or rejection of sorafenib, the trial-22 (phase 1/2) found a median OS of 65.6 months (95% CI 7.7–24.6) and a median PFS of 8.69 months (95% CI 1.8–5.4) with an acceptable safety profile for tremelimumab monotherapy. Tremelimumab plus durvalumab (anti-PD-L1), on the other hand, had a better overall benefit–risk ratio [28]. Furthermore, early growth of Ki67+ CD8 + T cells was linked to response to either the single treatment or the combination. This is the final trial that potentially leads to global regulatory clearance for a single drug checkpoint inhibitor. The focus and expectations have shifted to combination therapies in general.

#### *3.3.2 Dual therapeutic strategy using ICIs and anti-VEGF antibodies*

Based on the positive results of the IMbrave150 phase-3 trial 8, the combination of a PD1/PD-L1 inhibitor and a VEGF blocker has become a new strategy to treat advanced HCC [8]. The IMbrave150 experiment resulted in the approval of atezolizumab plus bevacizumab as first-line treatment for unresectable HCC in the United States and Europe, replacing the TKIs sorafenib and lenvatinib. Inhibition of PD-L1, which increases the immune response (especially T-effector cells), and inhibition of VEGF, which stimulates T-cell infiltration in the tumor microenvironment and overcomes VEGF-mediated immunosuppression, is thought to have synergistic antitumor efficacy [29].

The ORIENT-32 phase 2/3 trial compared sintilimab (anti-PD1) and IBI305 (a bevacizumab biosimilar) to sorafenib in systemic treatment-naive Chinese patients, similar to the IMbrave150 trial (NCT03794440). In comparison to sorafenib, sintilimab/IBI305 exhibited an elevated median OS and PFS (median OS: not attained vs. 10.4 months; median PFS: 41.2 weeks vs. 12.17 weeks) with acceptable tolerability of [30].

#### *3.3.3 Combination therapies of PD-1 and CTLA-4 inhibitors*

Immune checkpoint inhibitor therapy for cancer patients has undoubtedly been a big achievement in oncology in recent years, and it represents a huge stride forward as a novel type of immunotherapy in cancer treatment. The combined ICIs including (anti-CTLA-4, and anti-PD-1/L1) are currently being investigated in advanced HCC. The CheckMate 040 trial, which evaluated nivolumab with ipilimumab in 148 patients with advanced HCC who had developed resistance to sorafenib, yielded the first clinical data [31]. The underlined therapy has been approved by the FDA post successful results of the trials. Moreover, systemic steroids are needed to treat adverse events.

#### *3.3.4 Combination therapies of the checkpoint and multi-kinase inhibitors*

Anti-VEGF antibodies can be replaced with ICIs and TKIs to inhibit VEGF. Currently, several such combinations are being investigated. As a secondary outcome measure, cabinozantinib monotherapy is compared with sorafenib. In a phase 1b trial involving 104 patients with unresectable HCC, the combination of lenvatinib with pembrolizumab was found to have potential anticancer efficacy [32].

Finally, camrelizumab (SHR1210, anti-PD-1) and apatinib (rivoceranib, a TKI inhibits VEGFR2) were tested in the clinic. An ORR of 50% was observed in a phase 1 investigation of individuals with advanced HCC [33]. The combination therapies are being evaluated as a first-line treatment for patients with advanced HCC in the phase 3 clinical trial.

#### *3.3.5 Systemic treatment beyond ICIs*

The most common method of cancer immunotherapy is the attenuation of the immunological checkpoints PD1/PD-L1 and CTLA-4. LAG-3 is an alternative immunological checkpoint that suppresses T-cell function, indicating T-cell depletion. In phase 2 RELATIVITY-073 trial in advanced, ICI-naive HCC post-progression on prior TKI therapy, relatlimab, an antibody that blocks LAG-3, is being tested in combination with nivolumab. Additionally, a growing number of novel immunotherapeutic methods are being investigated. Where today's ICIs fail, such interventions could be effective. Adoptive transfer of NK or T cells to increase tumor infiltration, for example, could benefit patients whose tumors aren't infiltrated by effector immune cells.

Besides classic checkpoint inhibition, the majority of immunotherapies are still in the preclinical or early clinical stages, and these include allogeneic NK cells, CAR-T, as well as oncolytic viruses [34]. CAR-T cells targeting GPC3 are currently being studied in phase 1 trials. Moreover, autologous T cells expressing improved TCRs specific for AFP (AFP c332 T) are being tested in HLA-A2-positive people with advanced HCC in the first phase 1 experiment targeting AFP. Pexastimogene devacirepvec (Pexa-Vec) failed in the TRAVERSE phase 2b trial and the PHOCUS trial as a second-line monotherapy in advanced HCC [35, 36]. Pexa-Vec and nivolumab are currently being tested in a phase 1/2a experiment. Novel immunotherapeutic techniques have the potential to provide immunotherapy benefits to a larger number of patients. However, it is not yet obvious which approaches will enhance or even replace current systemic therapeutic strategies.

### **4. Other HCC immunotherapies**

#### **4.1 Adoptive cell therapy (ACT)**

In ACT combined with effector cells, lymphocytes are activated and/or amplified ex vivo before being reintroduced into the patients. Redirected peripheral blood T cells, TILs, CIK cells, NK cells, and lymphokine-activated killer cells (LAKs) are among the cell types that are used in this procedure. T-lymphocytes in the peripheral circulation have been genetically recoded to preferentially target tumor cells. The two basic techniques are chimeric antigen receptors (CARs) and transgenic tumor antigen-specific TCRs. CIK, TIL, and LAK therapies are not affected by the cancer-associated genes. Except in LAK, CIK, and CAR T cells, MHC-specific antitumor activity has been found in TIL and TCR-redirected cells. Usually, adoptive transplant cells are preconditioned with fludarabine and cyclophosphamide to promote lymphodepletion and enhance in vivo growth. Patients receiving LAK, CIK, or TIL treatment are often given IL-2 to assist the transferred cells' proliferation in vivo.

#### *Emerging Immunotherapy: Liver Cancer Microenvironment for Treatment DOI: http://dx.doi.org/10.5772/intechopen.106021*

Because of the technology's apparent complexity and absence of efficiency, the first attempts to use ACT to treat HCC never got to the clinical stage. The fact that LAK cells poorly develop ex-vivo and have a poor cytolytic impact in melanoma patients serves as an example of the intricacy of this system. HCC recurrence was reduced by using LAK cells as an additive following resection to reduce the risk of HCC recurrence. However, this had not improved survival. However, CIK cells are more cytotoxic and proliferative when compared with LAK cells. NKT cells principally contribute to the antitumor effect of this diverse population. In 2015, a multicenter, randomized phase III trial involving 226 patients demonstrated that combination immunotherapy with CIK cells increased PFS and OS of HCC patients following percutaneous ablation or curative surgical resection relative to the patients who did not receive combination therapy. Considering the underlined outcomes, the majority of institutions do not use ACT as adjuvant therapy, most likely due to a lack of in-house cell therapy facilities. From tumor samples (fresh), TILs were obtained followed by selecting the tumor-reactive growing cells on the basis of their autologous cell recognition. Next, these cells were amplified to produce many active cells. The effectiveness of combined TIL treatment was indicated in a Phase-I study with individuals who had HCC7. TILs were given to 15 of 17 patients, with doses up to 3 × 10 [9] cells administered with the least side effects. The major challenges for clinical usage are obtaining sufficient T-cells that are selective for tumor neoepitopes and shortening the underlined procedure.

NK cells have a wide spectrum of receptors that allow them to identify tumor cells even without prior sensitization or the acquisition of receptor reconfiguration. For clinical usage, their inability to grow in vitro may be overcome. Phase II clinical trials are now using allogeneic NK cells to treat patients who have an increased risk of HCC recurrence following surgery or TACE.

In the treatment of hematologic malignancies (such as leukemia, multiple myeloma, and lymphoma), CAR T cell therapy has shown significant promise; however, its use in solid tumors is still under investigation. CAR T cells express transmembrane, intracellular signaling domains, and antigen-recognition domains that are common features of CAR T cells. One-chain variable fragments produced from the variable heavy and light chains of monoclonal antibodies selective for certain tumor cell targets, which can be tumor antigens, usually make up the extracellular antigen-recognition domains. In HCC, GPC3 has emerged as the most specific and appealing target. The efficacy of orthotopic and patient-derived xenografts has been demonstrated in various animal models. One of the most serious issues with CAR T cells is off-target toxicity. This occurs when the expression of the targeting molecule is in non-tumor tissues.

According to several studies, AFP is often overexpressed in HCC. Due to its intracellular expression and secretion, TCR-based therapy is relatively more effective when compared with CAR-based therapies. In patients associated with HCC, four HLA-A2-restricted AFP epitopes were identified. TP53 hotspot mutations, which are common in HCC and HBV antigens, are two more possible targets for T-cells (TCR-engineered).

#### **4.2 Therapeutic vaccines**

The key stimulus for using cancer vaccines is to induce tumor-specific reactions with higher efficacy. The underlined impact can be obtained by de novo priming T-cells against antigens produced by tumor cells that do not generate a spontaneous response and further enhancing the remaining reactions or expanding the repertoire and breadth of tumor-specific responses. Vaccinations were once thought to be a stand-alone treatment. However, it is now obvious that they should be used in combination with ICIs or ACT. Combinations of ICIs could block these variables, making it easier for antitumor lymphocytes to accomplish their activities.

In situ therapeutic vaccines act by activating tumor-infiltrating APCs, which absorb and display endogenous TAAs. Classic tumor vaccines, on the other hand, rely on the exogenous delivery of antigens or antigen-pulsed DCs. Cancer antigens should be immunogenic enough to overcome the tolerance induced by multiple selfmolecules appearing on tumor cells, while also conferring selectivity for tumor cells and blocking the response of non-tumor cells. Antigen identity is uncertain in tumor lysate, which comprises self-molecules that could not confirm the accurate view of relevant TAA. Using tumor cell lysates as a treatment for HCC in a number of trials did not lead to consistent results.

TAAs including GPC-3, AFP, and telomerase have been addressed as HCC peptide vaccines (antigens specific). HCC patients have revealed spontaneous T-cell responses to the above antigens, suggesting that they are immunogenic in some way. In the majority of cases, T-cell sensitivity to their corresponding antigen is unclear. Hardly a few telomerase and GPC-3-targeting techniques have progressed to clinical evaluations, and none of them has yielded clinically relevant data that could serve as an active pharmaceutical candidate. One of the problems with the approach of therapeutic vaccination is tumor phenotypic heterogeneity and the real possibility that despite best efforts, some tumor cells will simply not be targeted by the vaccine, even if the vaccine is multivalent.

The identification of real tumor-specific antigens should be used to develop more immunogenic vaccinations. HLA peptidomics approaches are the first option that can be used to identify peptides that utilize peptides and serve as a unique immunological signature that CTLs may identify. On the basis of this method, a vaccine clinical evaluation has completed recruitment in HCC.

The use of neoantigens is a second approach. Their detection is based on a complicated pathway that involves analyzing mutations in tumor cells in comparison with wild-type cells. This method is utilized to investigate mutant gene expression as well as immune-associated factors including epitope process ability and HLA molecule interaction. Furthermore, the method has been used to anticipate significantly immunogenic neoantigens with antitumor potential as vaccines in different tumors, including glioblastoma and melanoma. There is a need for extensive studies to clinically evaluate HCC. Only a limited number of studies have been reported that relate the existence of mutations to specific immune responses. According to the results obtained from our ongoing research, mutations observed in HCC patients may generate peptides with stronger HLA-interacting potential when compared with nonmutated wild-type sequences. This research is still being conducted by our group. It has been shown that these peptides stimulate T-cells to recognize only the mutant sequence and not the wild type in HLA-transgenic mice, implying that the method could possibly be used as a vaccination for HCC.

#### **5. Locoregional therapies**

The immune system has developed to deal with microbial infections as well as severe tissue injuries. These situations are recognized by interconnected innate

#### *Emerging Immunotherapy: Liver Cancer Microenvironment for Treatment DOI: http://dx.doi.org/10.5772/intechopen.106021*

receptors, the function of which determines whether or not an adaptive immune response is produced and progresses. Furthermore, these activities may influence whether tumor antigens trigger immunization, tolerance, or not. As a result, hard efforts have been made over the years in order to develop cancerous tissue that seems like diseased or stressed tissue, which might encourage cytotoxic immunity's adaptive response. Immune cell death and the use of PAMPs are two important concepts to look into in this context.

Immunogenic cell death (ICD) occurs when cells secrete or synthesize alarmins, a group of proteins that signal and stimulate APCs, i.e., DCs. ICD is linked to ER stress, necroptosis or necrosis, the secretion of mitochondrial and nuclear substances, and the activation of the Type-I IFNs. Moreover, chemo and radiotherapies, as well as other physical stimuli, activate cell and tissue damage and enhance immunity against tumor progression.

The immune system is activated by entities other than viruses, bacteria, and other prokaryotic entities. This reactivity allows drugs such as inflammasome agonists, Toll-like receptor (TLR) agonists, MDA5 or RIGI agonists, and cGAS–STING agonists to be delivered locally, stimulating localized immunity. These substances are usually synthetic analogs or obtained from microbial products, and when administered systemically, cause systemic inflammation and sepsis-like cytokine secretion syndromes. They may be more potent in triggering an immunological response with fewer adverse effects when administered intratumorally. Microorganisms can boost antitumor immunity without using their immune-stimulating substances. Therefore, Bacillus Calmette-Guérin vaccine is used for the local treatment of superficial bladder carcinoma. Oncolytic virotherapy is an effective therapeutic technique against cancer progression. This technique employs viruses that proliferate specifically in cancerous cells in order to kill them, with promising results in HCC. But instead of the cytopathic effects of the viruses, it has become clear that most of the therapeutic benefits of virotherapy come from boosting immune responses that target tumor antigens. Also, spores of anerobic bacteria have been used to amplify immune responses against tumors, since they only germinate in hypoxic environments, which occur in tumor nodules. This is why some bacterial infections trigger immune stimulation that in turn target tumor cells.

Locoregional methods are highly recommended for the treatment of individuals with unresectable HCC. Catheter-based procedures (yttrium-90 irradiation and transarterial chemoembolization) and locoregional ablative treatments, either chemical (percutaneous ethanol injection) or thermal (thermal ablation), are examples of image-guided therapies (laser, microwave, and radiofrequency ablation, and cryoablation) [4]. HCC is favorable for local therapies that can trigger ICD or local delivery of PAMPs due to its easy availability to tumor-affected regions. Notably, multiple locoregional therapies can be used independently or in combination with systemic immunotherapies, to obtain an elevated level of immune activation. Following RFA, immunological responses are activated, and T-cells infiltrate the tumor. In patients with advanced HCC receiving tremelimumab, partial tumor ablation with RFA or TACE achieved a 26% and 89% response rate and disease control rate, respectively. Furthermore, 45% of stabilizations last longer than 26.07 weeks and have an OS of 53.45 weeks [22]. As a result of these encouraging findings, clinical trials involving the use of ICIs, whether alone or combined with other ICIs or bevacizumab, in accordance with chemo, radioembolization, or post-complete percutaneous or surgical ablation, have given considerable support.

#### **6. Reactions and resistivity**

It is critical to developing pretreatment baseline levels of T-cell infiltration and stimulation when evaluating response to checkpoint inhibition in different carcinomas. While the influence of CD4+ and CD8 + T-cell infiltration on survival post advanced HCC treatment using second-line PD1 inhibitors has been observed in the form of poor interactions and trends. The underlined results show that the impact is not as significant as originally assumed. According to the immunohistochemistry results, about 20% of advanced HCC tumors express PDL1. Tumor responses were reported in the CheckMate 040 trial independent of PDL1 expression. However, response rates were higher in patients with a minimum of 1% of tumor cells expressing PDL1. PDL1 expression in stromal immune cells as well as in tumor cells was elevated in pembrolizumab-treated patients who obtained objective remission. However, according to the obtained results, the responses were observed even in the absence of expression in both types of cells. In naive patients associated with PDL1-positive HCC, median OS was 70 weeks and 37.3 weeks (HR 0.80), accordingly. In the case of PDL1 negative HCC patients, after sorafenib and nivolumab treatment, the median OS was 72.6 weeks and 66 weeks (HR 0.84), respectively. Furthermore, a trend toward better OS with nivolumab monotherapy was observed in patients with increased tumor infiltration via CD3 + or CD8 + cells. In addition, various signatures of inflammatory genes (such as COX-2) were linked to an elevated response rate and OS. The underlined gene signatures were linked to inflammatory activities, cytolytic genes, IFN-associated genes, exhaustion markers, NK cell markers, and antigen presentation. In this view, these findings reveal an elevated level and activity of T cells and NK cells that utilize cytolysis and IFNγ as their primary antitumor effector mechanisms. In this study, the most complicated transcriptome classification, which includes a huge set of genes, was not found to be predictive of response. However, in the current evaluation, the number of patients for whom small data of RNA sequencing were existing, as large sample data could provide more definitive outcomes (positive or negative). Integrating genomics and transcriptomics into immunotherapy effectiveness will include comprehensive integrative analysis as well as obtaining biopsy samples before and during therapy.

Patients with objective remissions demonstrated potent CD3 + and CD8 + infiltration as compared with non-responders in paired HCC biopsy samples taken prior to and post two doses of tremelimumab. In the case of the combinations, objective HCC remissions were achieved regardless of PDL1 expression in nivolumab + ipilimumab treated cancerous cells. A single biomarker is insufficiently sensitive to provide timely clinical data. However, thorough immunohistological, mutational, and transcriptomic evaluations are required, as integrated multifactorial indices may be able to determine subgroups of individuals who would take advantage of ICI treatment. The significance of matching biopsies prior to and following treatment cannot be emphasized, since diagnostic biopsies for HCC are rarely taken.

The question of whether we are dealing with synergistic effects or just an additive impact arises when evaluating the enhanced combination of ICI therapeutic efficacy. Complementary analysis from major clinical studies is still lacking. Nevertheless, a subgroup analysis has reported a correlation between durvalumab, tremelimumab, or both in combinations. Furthermore, on day 15 after therapy began, an elevated level of proliferating Ki67 + CD8 + T cells among blood mononuclear cells was observed. In particular, in comparison with durvalumab, tremelimumab monotherapies, or the combined effect of a routine low dosage of tremelimumab with a similar dosage of durvalumab, the elevation in the underlined population of peripheral effector T-cells

#### *Emerging Immunotherapy: Liver Cancer Microenvironment for Treatment DOI: http://dx.doi.org/10.5772/intechopen.106021*

was found optimum for responders to an elevated priming dosage of durvalumab plus tremelimumab. The underlined combined therapies obtained the highest OS. It could be helpful to use biomarkers that are easily available to help design new combinations of therapies and to compare data between combinations. Significant TME changes were found in animal models with VEGFR blockade. The blockage of VEGFR improves PD1 inhibitory activity. According to multiple reported studies on mouse models, combined VEGFR and PD1 inhibition decreases M2-polarized macrophages and T-reg cells, enhances HCC cells and PDL1 expression in TAMs, and enhances normalized vasculature development triggered by CD4 + cells. Notably, effectiveness was achieved with a low dosage of anti-angiogenics (vascular normalizing rather than anti-vascular), offering a promising path of research into minimizing the associated toxicities.

The development of ADAs (anti-drug antibodies) that can affect the elimination of these drugs or neutralize their effectiveness is another viable cause of tumor resistance. The estimated prevalence of ADAs during monotherapies with anti-CTLA4 (ipilimumab), anti-PD1 (cemiplimab, nivolumab, and pembrolizumab), and anti-PDL1 (durvalumab and avelumab) agents is low, ranging from 0 to 12.7% in all tumor types. While no relevant impact of ADAs on efficiency has been noticed for nivoluma. ADAs, on the other hand, were found in up to 36% of NSCLC patients who had received atezolizumab and had a negative impact on systemic exposure to the drug as well as antitumor effectiveness. In the case of HCC, effectiveness (impact on OS) was poorer in the 20% of patients (ADA-positive by week 6) treated with bevacizumab and atezolizumab in a subanalysis of the IMbrave150 study. PD-L1 and CTLA4 are only two molecules that are involved in T cell exhaustion. There are many others on the surface of tumor cells that could compensate. Also, CTLs may have a hard time penetrating solid tumors, especially those that are encased in a fibrous capsule. This may also limit the effects of immunotherapy.

### **7. Management of immunotherapy toxicities**

### **7.1 Immune-associated side effects**

Immune checkpoints or coinhibitory receptors including CTLA-4 and PD-1 control T cell reactions and are efficient therapeutic targets [37, 38]. One of the drawbacks of the underlined advancements in the development of a novel spectrum of immune-related adverse events (irAEs), which are frequently distinct from the conventional toxicities associated with chemotherapy. Due to the rising use of ICIs in oncology, clinicians will progressively encounter both frequent and rare irAEs; hence, it is needed to increase attention regarding the clinical manifestation, evaluation, and managing these toxicities.

Unlike anti-CTLA-4-related adverse events, the risk of irAEs caused by PD-1/ PD-L1 inhibition is independent of dosage [39, 40]. The skin and gastrointestinal tract were the most commonly affected organ systems by anti-CTLA4 and PD-1/PD-L1 inhibitors, whereas the liver and the endocrine system were less frequently damaged [39, 40]. However, ipilimumab was found to be linked with a considerably elevated incidence of rash and colitis than anti-PD-1/PD-L1 medicines [41].

#### **7.2 irAEs management**

Since irAEs are linked with a large array of aggravating conditions in the HCC, hepatologists face numerous hurdles while detecting and treating them. First,

liver cirrhosis causes immunological dysfunction, which worsens over time [42]. Consequently, the immunological homeostasis linked with the liver in these patients is substantially damaged. Second, cirrhosis-related hepatic and extrahepatic consequences may overlap with or intensify symptoms mediated by irAEs [43]. Consequently, prior to ICI therapy, HCC patients should be carefully selected and evaluated [43].

Furthermore, the underlined approaches should be utilized for managing irAEs. First, strict surveillance is required, with weekly clinical controls, based on the intensity of the incidents. This is especially critical in patients with liver cirrhosis because distinguishing between problems (linked with cirrhosis) and irAEs can be difficult, and prematurely terminating a considerable antitumor therapy or initiating steroid therapy in cirrhotic patients might have serious implications [43].

Depending on the nature and severity of irAEs, it may be required to temporarily stop or permanently discontinue ICI therapy. With the exception of PD-1/PD-L1 driven rash, nephritis, adrenal insufficiency, and hypothyroidism, which recover after 1 month of treatment, permanent termination of ICI therapy should be addressed for irAEs of grade ≥ 3 [43]. There is a considerable risk of recurrence of irAEs when ICI medication is restarted after it has been discontinued: Twenty-five percent (22 of 40) of the 93 patients with irAEs of grade ≥ 2 who were treated with anti-PD-1/PD-L1 drugs had a recurrence of irAEs post-termination [44]. While recurrence of irAEs was linked with a more rapid onset of the early irAE, the frequency of the recurring irAEs did not vary [44]. TKIs used for HCC include sorafenib, lenvatinib, regorafenib and cabozantinib, all of which are associated with skin toxicity. However, the type of adverse effect and time course can help distinguish between ICI- and TKI-related events. For TKIs, the onset of rash is usually within weeks of starting and palmarplantar erythema is the most common AE, reported in 52% and 27% of patients receiving sorafenib and lenvatinib, respectively. 29 This compares with around 2% for PD1 inhibitors. Additionally, the relatively short half-life of TKIs results in rapid resolution of skin toxicity over the course of days, which contrasts with the weeks or months that may be required for ICI-related toxicity to resolve.

Glucocorticoids may be prescribed for irAEs of grade ≥ 2 (0.5–2 mg/kg/day prednisone PO or IV, depending on the kind and intensity of the irAEs). Topical, oral, and intravenous glucocorticoids, as well as oral or topical antihistamines, are used to treat cutaneous irAEs, which range from simple rash or itch to less common but more serious illnesses such as Stevens-Johnson syndrome (SJS) [43]. Stevens-Johnson syndrome (SJS) is a form of severe adverse drug reactions and is characterized by epidermal necrolysis. The disease has the unique expression of blisters on the skin and the affection of mucous membranes in the mouth, nose, eyes, and genitals. SJS is characterized by a large area of skin and mucosal epithelial cell shedding and typical performance on the oropharynx, eyes, urogenitals, and anal mucosa. SJS has less than 10% of body surface area involvement. Steroids should be continued for at least 3 days before being reduced over 1–4 weeks [21, 45]. It should be noted that steroids are only beneficial in non-viral-associated chronic liver disease. If viruses are involved (HBV, HCV), steroids will simply permit virus replication to increase, and when steroids are withdrawn, a severe exacerbation of chronic liver disease may be seen.

Differential diagnosis is required for gastrointestinal irAEs, notably colitis and/ or diarrhea, to rule out infectious illnesses and medication adverse effects [43]. For grades 2 and ≥ 3, glucocorticoids should be started, and hospitalization with sigmoidoscopy/colonoscopy should be considered. Moreover, immunosuppressive medication should be added early in the case of glucocorticoid failure [43, 46]. Depending on the

*Emerging Immunotherapy: Liver Cancer Microenvironment for Treatment DOI: http://dx.doi.org/10.5772/intechopen.106021*

steroid reaction and the severity of clinical presentation, discontinuation should be done over 2–8 weeks [21, 45].

Immune-related hepatitis is particularly difficult to diagnose and treat in individuals with HCC who are receiving ICI therapy [43]. However, early contact with an experienced hepatologist is thus strongly advised. Intrahepatic growth of the tumor, HBV/HCV flares, and adverse events linked with hepatotoxic medication, ascites, cholestasis, and CMV reactivation should all be ruled out before a diagnosis of immune-associated hepatitis is made. A liver biopsy should also be conducted prior to the administration of steroids [43].

Pneumonitis is an irAE that can be life-threatening. Hence, a prompt and extensive differential diagnosis should be conducted with suspected pneumonitis, including the exclusion of portopulmonary hypertension, viral etiologies, and hepatopulmonary syndrome [43]. Steroids should be started for grade 2 and discontinued over a period of 4–6 weeks [21]. Post glucocorticoid failure, infliximab (which is inflammatory by inhibiting TNFα) or mycophenolate mofetil (an immunosuppressive compound that inhibits inosine monophosphate dehydrogenase) may be administered [43]. It should be noted that therapeutic approaches involving prolonged immunosuppression increase the risk for selected infectious diseases and tumor types that usually never develop in the presence of intact immune surveillance.

#### **8. Future directions**

The licensing of the initial ICIs in advanced HCC and their clinical efficacy have revolutionized the concept of cancer immunotherapy. However, this field still has to address three major questions: Is immunotherapy beneficial in the preclinical stage? If so, it will reduce the risk of disease progression to cancer. In addition to PD-1/ PD-L1/CTLA-4 suppression, which immunological treatments have antitumor effects in HCC? Which therapy options exist for patients not responding to the presently approved ICIs? Perhaps immunomodulation with histone deacetylase inhibitors (HDACi) in combination with ICI would permit a sustained antitumor response with reduced risk of adverse effects.

In response to the first question, various clinical studies in the initial and intermediate stages have reported the use of ICIs. It's uncertain whether checkpoint inhibitor exhibit regimens are a TACE alternative. As an alternative, the RENOTACE and ABC-HCC trials will test atezolizumab with bevacizumab and regorafenib plus nivolumab. Patients above the up-to-seven criteria, i.e., the subgroup with a relatively great tumor burden at an advanced stage, were recruited for RENOTACE, whereas patients with the whole spectrum of intermediate stages of disease were targeted for ABC-HCC. In addition, the initial trials examining ICIs for neoadjuvant approaches are currently in progress. The underlined collection of trials will look at the safety and efficacy of immunotherapy in the initial and intermediate stages from a variety of perspectives, providing high-quality data that will be useful in understanding the contribution of ICIs in the underlined situations.

To address the second question, there are a number of treatments that are currently being evaluated in clinical trials, which include the use of oncolytic viruses, CAR T/ NK cells, and LAG-3 checkpoint inhibitors. These treatments might help patients with established ICIs who are unresponsive or have failed to respond to the treatment.

The third question may also be addressed by the above new immunotherapeutic strategies. A subset of patients, particularly those with an immunological desert TME, is likely to take advantage less of immunotherapy. Although immunotherapy has made tremendous advances. It should not be overlooked when considering treatment options for patients who may benefit from existing and future specialized therapies.
