Curing mice with large tumors by locally delivering combinations of immunomodulatory antibodies

Cationic nanoparticles enhance T cell tumor infiltration and antitumor immune responses to a melanoma vaccine

In clinical settings, cancer vaccines as monotherapies have displayed limited success compared to other cancer immunotherapeutic treatments. Nanoscale formulations have the ability to increase the efficacy of cancer vaccines by combatting the immunosuppressive nature of the tumor microenvironment. Here, we have synthesized a previously unexplored cationic polymeric nanoparticle formulation using polyamidoamine dendrimers and poly(d,l-lactic-co-glycolic acid) that demonstrate adjuvant properties in vivo. Tumor-challenged mice vaccinated with an adenovirus-based cancer vaccine [encoding tumor-associated antigen (TAA)] and subsequently treated with this nanoparticulate formulation showed significant increases in TAA-specific T cells in the peripheral blood, reduced tumor burden, protection against tumor rechallenge, and a significant increase in median survival. An investigation into cell-based pathways suggests that administration of the nanoformulation at the site of the developing tumor may have created an inflammatory environment that attracted activated TAA-specific CD8⁺ T cells to the vicinity of the tumor, thus enhancing the efficacy of the vaccine.

Engineering of a trispecific tumor-targeted immunotherapy incorporating 4-1BB co-stimulation and PD-L1 blockade

Co-stimulatory 4-1BB receptors on tumor-infiltrating T cells are a compelling target for overcoming resistance to immune checkpoint inhibitors, but initial clinical studies of 4-1BB agonist mAbs were accompanied by liver toxicity. We sought to engineer a tri-specific antibody-based molecule that stimulates intratumoral 4-1BB and blocks PD-L1/PD-1 signaling without systemic toxicity and with clinically favorable pharmacokinetics. Recombinant fusion proteins were constructed using scMATCH3 technology and humanized antibody single-chain variable fragments against PD-L1, 4-1BB, and human serum albumin. Paratope affinities were optimized using single amino acid substitutions, leading to design of the drug candidate NM21-1480. Multiple in vitro experiments evaluated pharmacodynamic properties of NM21-1480, and syngeneic mouse tumor models assessed antitumor efficacy and safety of murine analogues. A GLP multiple-dose toxicology study evaluated its safety in non-human primates. NM21-1480 inhibited PD-L1/PD-1 signaling with a potency similar to avelumab, and it potently stimulated 4-1BB signaling only in the presence of PD-L1, while exhibiting an EC₅₀ that was largely independent of PD-L1 density. NM21-1480 exhibited high efficacy for co-activation of pre-stimulated T cells and dendritic cells. In xenograft models in syngeneic mice, NM21-1480 induced tumor regression and tumor infiltration of T cells without causing systemic T-cell activation. A GLP toxicology study revealed no evidence of liver toxicity at doses up to 140 mg/kg, and pharmacokinetic studies in non-human primates suggested a plasma half-life in humans of up to 2 weeks. NM21-1480 has the potential to overcome checkpoint resistance by co-activating tumor-infiltrating lymphocytes without liver toxicity.

Antibodies to EGF Receptor Family Members Can Upregulate Tumor Immunity

Immunologic mechanisms influence how a cancer patient responds to therapy. Monoclonal antibodies (mAbs) to the epidermal growth factor receptor are clinically approved, and a lung cancer vaccine inducing antibodies to epidermal growth factor (EGF) has some beneficial clinical effects. We tested the hypothesis that mAbs to epidermal growth factor receptor, EGF, and tumor growth factor alpha (TGF-α), in addition to any other effects, can facilitate the generation of a tumor-destructive immunologic response. Data from studies with mouse tumors showed that all 3 of these mAbs stimulated the in vitro generation of a Th1 response with tumor cells killed by spleen cells from mice with SW1 melanoma, B16 melanoma, or ID8 ovarian carcinoma. The mAb to TGF-α was most effective, and tumor lines releasing TGF-α were more sensitive than lines not releasing TGF-α. Stimulated by these findings we then performed pilot experiments in which mice with SW1 melanoma were injected with mAbs intraperitoneally or with a combination of the 2. A combination of anti-TGF-α and anti-PD-1 mAbs could cure mice with established tumor while single anti-TGF-α or anti-PD1 mAbs could not.

Tumors establish resistance to immunotherapy by regulating Treg recruitment via CCR4

BACKGROUND

Checkpoint inhibitors (CPIs) such as anti-PD(L)-1 and anti-CTLA-4 antibodies have resulted in unprecedented rates of antitumor responses and extension of survival of patients with a variety of cancers. But some patients fail to respond or initially respond but later relapse as they develop resistance to immune therapy. One of the tumor-extrinsic mechanisms for resistance to immune therapy is the accumulation of regulatory T cells (T_reg) in tumors. In preclinical and clinical studies, it has been suggested that tumor trafficking of T_reg is mediated by CC chemokine receptor 4 (CCR4). Over 90% of human T_reg express CCR4 and migrate toward CCL17 and CCL22, two major CCR4 ligands that are either high at baseline or upregulated in tumors on CPI treatment. Hence, CCR4 antagonism has the potential to be an effective antitumor treatment by reducing the accumulation of T_reg into the tumor microenvironment (TME).

METHODS

We developed in vitro and in vivo models to assess T_reg migration and antitumor efficacy using a potent and selective CCR4 antagonist, CCR4-351. We used two separate tumor models, Pan02 and CT26 mouse tumors, that have high and low CCR4 ligand expression, respectively. Tumor growth inhibition as well as the frequency of tumor-infiltrating T_reg and effector T cells was assessed following the treatment with CCR4 antagonist alone or in combination with CPI.

RESULTS

Using a selective and highly potent, novel small molecule inhibitor of CCR4, we demonstrate that migration of CCR4⁺ T_reg into the tumor drives tumor progression and resistance to CPI treatment. In tumor models with high baseline levels of CCR4 ligands, blockade of CCR4 reduced the number of T_reg and enhanced antitumor immune activity. Notably, in tumor models with low baseline level of CCR4 ligands, treatment with immune CPIs resulted in significant increases of CCR4 ligands and T_reg numbers. Inhibition of CCR4 reduced T_reg frequency and potentiated the antitumor effects of CPIs.

CONCLUSION

Taken together, we demonstrate that CCR4-dependent T_reg recruitment into the tumor is an important tumor-extrinsic mechanism for immune resistance. Blockade of CCR4 led to reduced frequency of T_reg and resulted in increased antitumor activity, supporting the clinical development of CCR4 inhibitors in combination with CPI for the treatment of cancer.

STATEMENT OF SIGNIFICANCE

CPI upregulates CCL17 and CCL22 expression in tumors and increases T_reg migration into the TME. Pharmacological antagonism of the CCR4 receptor effectively inhibits T_reg recruitment and results in enhanced antitumor efficacy either as single agent in CCR4 ligand^high tumors or in combination with CPIs in CCR4 ligand^low tumors.

Intratumoural administration and tumour tissue targeting of cancer immunotherapies

Immune-checkpoint inhibitors and chimeric antigen receptor (CAR) T cells are revolutionizing oncology and haematology practice. With these and other immunotherapies, however, systemic biodistribution raises safety issues, potentially requiring the use of suboptimal doses or even precluding their clinical development. Delivering or attracting immune cells or immunomodulatory factors directly to the tumour and/or draining lymph nodes might overcome these problems. Hence, intratumoural delivery and tumour tissue-targeted compounds are attractive options to increase the in situ bioavailability and, thus, the efficacy of immunotherapies. In mouse models, intratumoural administration of immunostimulatory monoclonal antibodies, pattern recognition receptor agonists, genetically engineered viruses, bacteria, cytokines or immune cells can exert powerful effects not only against the injected tumours but also often against uninjected lesions (abscopal or anenestic effects). Alternatively, or additionally, biotechnology strategies are being used to achieve higher functional concentrations of immune mediators in tumour tissues, either by targeting locally overexpressed moieties or engineering 'unmaskable' agents to be activated by elements enriched within tumour tissues. Clinical trials evaluating these strategies are ongoing, but their development faces issues relating to the administration methodology, pharmacokinetic parameters, pharmacodynamic end points, and immunobiological and clinical response assessments. Herein, we discuss these approaches in the context of their historical development and describe the current landscape of intratumoural or tumour tissue-targeted immunotherapies.

Antitumor efficacy and reduced toxicity using an anti-CD137 Probody therapeutic

Costimulation via CD137 (4-1BB) enhances antitumor immunity mediated by cytotoxic T lymphocytes. Anti-CD137 agonist antibodies elicit mild liver inflammation in mice, and the maximum tolerated dose of Urelumab, an anti-human CD137 agonist monoclonal antibody, in the clinic was defined by liver inflammation-related side effects. A protease-activated prodrug form of the anti-mouse CD137 agonist antibody 1D8 (1D8 Probody therapeutic, Pb-Tx) was constructed and found to be selectively activated in the tumor microenvironment. This construct, which encompasses a protease-cleavable linker holding in place a peptide that masks the antigen binding site, exerted antitumor effects comparable to the unmodified antibody but did not result in liver inflammation. Moreover, it efficaciously synergized with both PD-1 blockade and adoptive T-cell therapy. Surprisingly, minimal active Pb-Tx reached tumor-draining lymph nodes, and regional lymphadenectomy did not abrogate antitumor efficacy. By contrast, S1P receptor-dependent recirculation of T cells was absolutely required for efficacy. The preferential cleavage of the anti-CD137 Pb-Tx by tumor proteases offers multiple therapeutic opportunities, including neoadjuvant therapy, as shown by experiments in which the Pb-Tx is given prior to surgery to avoid spontaneous metastases.

Modulation of the immune microenvironment of high-risk ductal carcinoma in situ by intralesional pembrolizumab injection

Ductal carcinoma in situ (DCIS) is a risk factor for the subsequent development of invasive breast cancer. High-risk features include age <45 years, size >5 cm, high-grade, palpable mass, hormone receptor negativity, and HER2 positivity. We have previously shown that immune infiltrates are positively associated with these high-risk features, suggesting that manipulating the immune microenvironment in high-risk DCIS could potentially alter disease progression. Patients with high-risk DCIS were enrolled in this 3 × 3 phase 1 dose-escalation pilot study of 2, 4, and 8 mg intralesional injections of the PD-1 immune checkpoint inhibitor, pembrolizumab. Study participants received two intralesional injections, three weeks apart, prior to surgery. Tissue from pre-treatment biopsies and post-treatment surgical resections was analyzed using multiplex immunofluorescence (mIF) staining for various immune cell populations. The intralesional injections were easily administered and well-tolerated. mIF analyses demonstrated significant increases in total T cell and CD8+ T cell percentages in most patients after receiving pembrolizumab, even at the 2 mg dose. T cell expansion was confined primarily to the stroma rather than within DCIS-containing ducts. Neither cleaved caspase 3 (CC3) staining, a marker for apoptosis, nor DCIS volume (as measured by MRI) changed significantly following treatment. Intralesional injection of pembrolizumab is safe and feasible in patients with DCIS. Nearly all patients experienced robust total and CD8+ T cell responses. However, we did not observe evidence of cell death or tumor volume decrease by MRI, suggesting that additional strategies may be needed to elicit stronger anti-tumor immunity.

The emerging role of co-stimulatory molecules and their agonistic mAb-based combination therapies in melanoma

Although anti-PD-1/L1 and anti-CTLA-4 antibodies, the validated immune checkpoint blockades, can elicit durable long-lasting antitumor immunity and improve the clinical outcomes of melanoma treatment, there are still a fraction of patients who did not receive therapeutic benefits as expected. In addition to findings of blocking the co-inhibitory pathways, the preclinical and clinical evidence suggests that triggering the co-stimulatory pathways through agonists such as CD137, OX40, CD40, GITR and CD27 may be a rational next step for melanoma therapy. In this review, we discuss the progress of studies on these co-stimulatory molecules in terms of their promising therapeutic effects and underlying antitumor mechanisms, and provide a review of the possible combinations that orchestrate the interplay of co-stimulatory agonistic mAbs and other therapies for treating melanoma, including inhibitory immune checkpoint mAbs, adoptive T cell therapy, chemotherapy and radiotherapy. We also briefly present the limitations and challenges involved in these co-stimulatory agonistic mAb-based combination strategies for melanoma patients.

Intratumoral Immunotherapy: From Trial Design to Clinical Practice

Systemic immunotherapies such as immune checkpoint blockade targeted at PD(L)1 and CTLA4 have demonstrated their ability to provide durable tumor responses and long-term overall survival benefits for some patients in several solid tumor types. However, a majority of patients remain resistant to these treatments and a significant proportion of them develop severe autoimmune and inflammatory adverse events. Preclinical studies have demonstrated that intratumoral injections of immunostimulatory products (oncolytics, pattern recognition receptor agonists,…) that are able to trigger type I IFN release and enhance tumor antigen presentation on immune cells could generate a strong antitumor immunity and overcome the resistance to systemic immune checkpoint blockade therapies. The intratumoral immunotherapy strategies that are currently in clinical development offer a unique therapeutic and exploratory setting to better understand the immune contexture across tumor lesions of patients with metastatic cancer. Also these local therapeutic products could turn cold tumors into hot and improve the response rates to cancer immunotherapies while diminishing their systemic exposure and toxicities. Intratumoral immunotherapies could prime or boost the immunity against tumors and therefore radically change the combinatorial therapeutic strategies currently pursued for metastatic and local cancers to improve their long-term survival. We aimed to review and discuss the scientific rationale for intratumoral immunotherapy, the challenges raised by this strategy in terms of drug development within clinical trials and the current state-of-the-art regarding the clinical practice of this innovative approach.

Distinct immunopathology in the early stages between different antiresorptives-related osteonecrosis of the jaw-like lesions in mice

There is limited information about denosumab-related osteonecrosis of the jaw (DRONJ), unlike bisphosphonate-related ONJ (BRONJ). The mode of action is clearly different between denosumab and bisphosphonates. DRONJ occurs mainly following tooth extraction in cancer patients treated with the combination of denosumab and other drugs including chemotherapy. However, DRONJ animal models similar to these clinical situations have not been developed. The aims of this study were to 1) create a new model of high-prevalence chemotherapy/anti-RANKL antibody-related ONJ-like lesions to mimic patients receiving a denosumab/chemotherapy combination; and 2) compare the histopathological and immunopathological findings in the early stages of BRONJ-like and anti-RANKL antibody-related ONJ-like lesions. Cyclophosphamide (CY) and anti-mouse RANKL monoclonal antibody (mAb) or zoledronate combination therapy (CY/mAb and CY/ZA, respectively) was performed to create ONJ-like lesions in female C57BL/6J mice. Both maxillary first molars were extracted at 3 weeks after drug administration. The animals were euthanized at either 2 or 4 weeks after tooth extraction. Increased necrotic bone and empty lacunae with decreased living bone and osteocyte numbers were common histopathological findings in CY/mAb- and CY/ZA-induced impaired wound healing at 4 weeks after tooth extraction, and they were diagnosed as ONJ-like lesions based on validation of BRONJ and DRONJ in humans. In areas of impaired healing at 2 weeks post-extraction, decreases in angiogenesis and F4/80⁺LYVE-1^- macrophages were noted as common immunopathological findings, although anti-angiogenesis was worse with CY/mAb than with CY/ZA. Interestingly, CY/mAb did not reduce F4/80⁺LYVE-1⁺ cells and normal lymphangiogenesis remained, whereas CY/ZA profoundly suppressed the larger size of F4/80⁺LYVE-1⁺ cells, similar to vessels with a concomitant decrease in lymphangiogenesis. Therefore, the distribution of the larger size of F4/80⁺LYVE-1⁺ cells differed in the early stages between different antiresorptive-induced ONJ-like lesions in conjunction with lymphangiogenesis, although the histopathological findings were similar. These findings suggest that the pathogenesis of BRONJ and DRONJ may differ due to the distributions of F4/80⁺LYVE-1⁺ tube-like-structured cells.

CD137, an attractive candidate for the immunotherapy of lung cancer

Immunotherapy has become a hotspot in cancer therapy in recent years. Several immune checkpoints inhibitors have been used to treat lung cancer. CD137 is a kind of costimulatory molecule that mediates T cell activation, which regulates the activity of immune cells in a variety of physiological and pathological processes. Targeting CD137 or its ligand (CD137L) has been studied, aiming to enhance anticancer immune responses. Accumulating studies show that anti-CD137 mAbs alone or combined with other drugs have bright antitumor prospects. In the following, we reviewed the biology of CD137, the antitumor effects of anti-CD137 Ab monotherapy and the combined therapy in lung cancer.

BTLA blockade enhances Cancer therapy by inhibiting IL-6/IL-10-induced CD19high B lymphocytes

Background

The standard treatment for epithelial ovarian carcinoma (EOC) is surgery followed by platinum/paclitaxel-based chemotherapy, but the overall survival rate is poor. The purpose of this study was to investigate the therapeutic potential of chemotherapy combined with inhibition of B and T lymphocyte attenuator (BTLA) for clinical use to treat EOC.

Methods

Initially, we evaluated the potential application of chemotherapy combined with anti-BTLA antibody in an animal model. We then analyzed the distribution and regulation of BTLA expression on immunocytes in vitro. Finally, we examined the correlation between BTLA expression levels in cancerous tissues and prognosis in 254 EOC cases.

Results

The combination of chemotherapy and anti-BTLA antibody for inhibiting BTLA significantly reduced peritoneal tumor volume and extended survival in tumor-bearing mice. In addition, BTLA could be identified mostly on B lymphocytes, especially on CD19^hi B cells, rather than on T lymphocytes and natural killer cells. Under regulation of interleukins 6 and 10, more BTLA⁺CD19^hi B lymphocytes could be induced through AKT and STAT3 signaling pathways. Detectable BTLA expression in ovarian cancerous tissues was associated with worse disease-free and overall survivals of EOC patients.

Conclusions

BTLA detected in cancerous tissues can predict poor outcome of EOC patients. Inhibition of BTLA combined with chemotherapy can elevate immune activation and generate potent anti-tumor effects. Thus, the combination of chemotherapy and anti-BTLA antibody may hold potential clinical application for the treatment of EOC patients.

Trial registration

The Trial Registration Number was NCT00854399.

CD137 ligand feedback upregulates PD-L1 expression on lung cancer via T cell production of IFN-γ

BACKGROUND

The expression of PD-L1 and its regulation in tumors remains unclear. The importance of IFN-γ in upregulating the PD-L1 expression in various tumors, and the effects of other essential cytokines in the tumor microenvironment (TME), need to be further elucidated.

METHODS

Constitutive expression of PD-L1 and CD137L in all 13 lung cancer cell lines were tested by flow cytometry. CD137L mRNA of lung cancer cell lines was detected by RT-PCR. PD-L1 expression rates following stimulation with these cytokines (IFN-γ, TNFα and IL2) were measured. After coculture of cells expressing CD137L (lung cancer cells or 293FT cells transfected with CD137L plasmid) with T cells, the PDL1 expression of lung cancer cells and IFN-γ in supernatant was detected.

RESULTS

Our data revealed that adenocarcinoma and squamous cell carcinoma cells had the highest positive expression rate. IFN-γ was the core-inducing factor for enhancing the PD-L1 expression. CD137L was also widely expressed in the lung cancer cell lines at the mRNA level, whereas its expression was generally low at the protein level. However, the low expression of CD137L protein was still enough to induce T cells to produce IFN-γ, which subsequently increased the PD-L1 expression by lung cancer cells. The CD137 signal induces IFN-γ secretion by T cells, which stimulates high-level of PD-L1 expression in cancer cells; this negative immune regulation may represent a mechanism of immune escape regulation.

CONCLUSIONS

CD137L mRNA was widely expressed in lung cancer cell lines whereas levels of protein expression were generally low. The low level of CD137L protein was still enough to induce T cells to produce IFN-γ that subsequently increased PD-L1 expression. The CD137L-induced negative immune regulation may represent a mechanism of immune escape.

Tumor Regression and Cure Depends on Sustained Th1 Responses

Supplemental Digital Content is available in the text.

While immunomodulatory monoclonal antibodies (mAbs) have therapeutic efficacy against many tumors, few patients are cured. Attempting to improve their therapeutic efficacy we have applied the TC1 mouse lung carcinoma model and injected established subcutaneous tumors intratumorally with 3 weekly doses of various combinations of mAbs. Combinations of mAbs to CTLA4/PD1/CD137 (the 3 mAb combination) and to CTLA4/PD1/CD137/CD19 (the 4 mAb combination) were most efficacious to induce complete regression of both the injected tumor and an untreated tumor in the same mouse. Tumor cure was consistently associated with shifting a Th2 to a Th1 response in tumor-draining lymph nodes and spleen and it involved epitope specific and long-lived memory T cells as well as M1 macrophages. This shift and accompanying tumor rejection was harder to achieve as the treated tumors increased in size. Relapse of tumors which had initially regressed following treatment with immunomodulatory mAbs was associated with return of a Th2 microenvironment in tumors, tumor-draining lymph nodes and spleens rather than the emergence of immune-resistant tumor cells. While mAbs to CTLA4 plus PD-1 were therapeutically ineffective, combining the 2 of them with intraperitoneal cisplatin, 10 mg/kg, induced long-term complete tumor regression in most mice with small TC1 tumors and the therapeutic efficacy against larger tumors improved by administrating cisplatin together with the 3 or 4 mAb combination.

Immunotherapy with Monoclonal Antibodies in Lung Cancer of Mice: Oxidative Stress and Other Biological Events

Background: Lung cancer (LC) is a major leading cause of death worldwide. Immunomodulators that target several immune mechanisms have proven to reduce tumor burden in experimental models through induction of the immune microenvironment. We hypothesized that other biological mechanisms may also favor tumor burden reduction in lung cancer-bearing mice treated with immunomodulators. Methods: Tumor weight, area, T cells and tumor growth (immunohistochemistry), oxidative stress, apoptosis, autophagy, and signaling (NF-κB and sirtuin-1) markers were analyzed (immunoblotting) in subcutaneous tumor of BALB/c mice injected with LP07 adenocarcinoma cells treated with monoclonal antibodies (CD-137, CTLA-4, PD-1, and CD-19, N = 9/group) and non-treated control animals. Results: Compared to non-treated cancer mice, in tumors of monoclonal-treated animals, tumor area and weight and ki-67 were significantly reduced, while T cell counts, oxidative stress, apoptosis, autophagy, activated p65, and sirtuin-1 markers were increased. Conclusions: Immunomodulators elicited a reduction in tumor burden (reduced tumor size and weight) through decreased tumor proliferation and increased oxidative stress, apoptosis, autophagy, and signaling markers, which may have interfered with the immune profile of the tumor microenvironment. Future research should be devoted to the elucidation of the specific contribution of each biological mechanism to the reduced tumor burden.

Antitumor T-cell Homeostatic Activation Is Uncoupled from Homeostatic Inhibition by Checkpoint Blockade

T-cell transfer into lymphodepleted recipients induces homeostatic activation and potentiates antitumor efficacy. In contrast to canonical T-cell receptor-induced activation, homeostatic activation yields a distinct phenotype and memory state whose regulatory mechanisms are poorly understood. Here, we show in patients and murine models that, following transfer into lymphodepleted bone marrow transplant (BMT) recipients, CD8⁺ T cells undergo activation but also simultaneous homeostatic inhibition manifested by upregulation of immune-checkpoint molecules and functional suppression. T cells transferred into BMT recipients were protected from homeostatic inhibition by PD-1/CTLA4 dual checkpoint blockade (dCB). This combination of dCB and BMT-"immunotransplant"-increased T-cell homeostatic activation and antitumor T-cell responses by an order of magnitude. Like homeostatic activation, homeostatic inhibition is IL7/IL15-dependent, revealing mechanistic coupling of these two processes. Marked similarity in ex vivo modulation of post-BMT T cells in mice and patients is promising for the clinical translation of immunotransplant (NCT03305445) and for addressing homeostatic inhibition in T-cell therapies. SIGNIFICANCE: For optimal anticancer effect, T-cell therapies including chimeric antigen receptor T-cell, tumor-infiltrating lymphocyte, and transgenic T-cell therapies require transfer into lymphodepleted recipients and homeostatic activation; however, concomitant homeostatic inhibition mitigates T-cell therapies' efficacy. Checkpoint blockade uncouples homeostatic inhibition from activation, amplifying T-cell responses. Conversely, tumors nonresponsive to checkpoint blockade or BMT are treatable with immunotransplant.See related commentary by Ansell, p. 1487.This article is highlighted in the In This Issue feature, p. 1469.

Reduced lung cancer burden by selective immunomodulators elicits improvements in muscle proteolysis and strength in cachectic mice

Identification of to what extent tumor burden influences muscle mass independently of specific treatments for cancer-cachexia remains to be elucidated. We hypothesized that reduced tumor burden by selective treatment of tumor with immunomodulators may exert beneficial effects on muscle wasting and function in mice. Body and muscle weight, grip strength, physical activity, muscle morphometry, apoptotic nuclei, troponin-I systemic levels, interleukin-6, proteolytic markers, and tyrosine release, and apoptosis markers were determined in diaphragm and gastrocnemius muscles of lung cancer (LP07 adenocarcinoma cells) mice (BALB/c) treated with monoclonal antibodies (mAbs), against immune check-points and pathways (CD-137, cytotoxic T-lymphocyte associated protein-4, programed cell death-1, and CD-19; N = 10/group). Nontreated lung cancer cachectic mice were the controls. T and B cell numbers and macrophages were counted in tumors of both mouse groups. Compared to nontreated cachectic mice, in the mAbs-treated animals, T cells increased, no differences in B cells or macrophages, the variables final body weight, body weight and grip strength gains significantly improved. In diaphragm and gastrocnemius of mAbs-treated cachectic mice, number of apoptotic nuclei, tyrosine release, proteolysis, and apoptosis markers significantly decreased compared to nontreated cachectic mice. Systemic levels of troponin-I significantly decreased in treated cachectic mice compared to nontreated animals. We conclude that reduced tumor burden as a result of selective treatment of the lung cancer cells with immunomodulators elicits per se beneficial effects on muscle mass loss through attenuation of several biological mechanisms that lead to increased protein breakdown and apoptosis, which translated into significant improvements in limb muscle strength but not in physical activity parameters.

Inflammatory cytokines and change of Th1/Th2 balance as prognostic indicators for hepatocellular carcinoma in patients treated with transarterial chemoembolization

Tumor-associated immune response plays a critical role in cancer pathogenesis. This study evaluated clinical implications of T cell cytokines and regulatory T cells (Tregs) in HCC patients treated with TACE. Whole blood was obtained for analysis of T cell cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12p70, IL-13, IL-17A, IL-22, IFN-γ, and TNF-α) and Tregs from 142 HCC patients. Patients with CTP class A had a significantly lower proportion of detectable IL-4 or IL-6, but a higher proportion of detectable IL-22 than patients with CTP class B/C. IL-6 level was well correlated with tumor stage and undetectable IL-17A was associated with extrahepatic metastasis. The overall survival rate was significantly higher in patients who had undetectable IL-6 or detectable IL-22 than patients who did not. IL-6 among cytokines remained independently predictive factor for survival. Increased IFN-γ/IL-10 ratio and no increase in IL-6 level following TACE were associated with prolonged survival, and baseline Tregs could affect Th1/Th2 balance. T cell cytokines are associated with a variety of clinical aspects of HCC, and IL-6 is the most significant predictor of survival. A shift toward increased Th1 response and no increase in IL-6 level exert favorable immunologic effects on HCC prognosis.

From the Hellstrom paradox toward cancer cure

Several decades ago we published some of the first papers showing that both murine and human cancers are recognized in vitro as immunologically foreign and that this is the case also in the presence of a growing tumor. The latter situation, sometimes referred to as the Hellstrom paradox, implies that the tumor is protected in vivo by a highly immunosuppressive environment. After many disappointments, the discovery that tumor-related immunosuppression can be counteracted by administrating monoclonal antibodies (mAbs) to checkpoint inhibitors such as CTLA-4, PD-1, and PD-L1 is now revolutionizing cancer therapy. Over the past several years we have applied mouse models in attempts to further improve the ability of such mAbs to cause long-term complete tumor rejection. This review is focused on that work and emphasizes that successful immunotherapy is associated with a shift from a tumor-promoting Th2 inflammation to a tumor-inhibiting Th1 response.

Preclinical evaluation of an innovative anti-TAM approach based on zoledronate-loaded erythrocytes

In tumor microenvironment, tumor-associated macrophages (TAMs) are implicated in cancer sustainment, metastasis, and drug resistance, raising a growing interest as targets in cancer therapy. Since the bisphosphonate zoledronate has proven to affect TAMs' functions, the anti-tumor effect of single or repeated administrations of red blood cells (RBCs) encapsulating zoledronate was evaluated in a mouse model of mammary carcinoma. The obtained results showed that loaded RBCs, but not free zoledronate, caused a significant (p < 0.01) and time-lasting reduction of TAMs' extent in tumor mass of Balb/C mice inoculated with murine mammary carcinoma T41 cells; in addition, a significant reduction (p < 0.05) of tumor growth rate has been obtained only following repeated administrations of zoledronate-loaded RBCs. The anti-tumor effect was secondary to the early depletion of spleen macrophages. Moreover, by assessing the IgG2a/IgG1 ratio, a prevalence of Th1 cytotoxic response in tumor-bearing mice receiving zoledronate by means of RBCs has been observed. These encouraging findings provide further evidence for the central role played by macrophages in tumor setting and highlight the suitability of zoledronate-loaded RBCs as pharmacological agents in depleting, even if indirectly, TAMs and, thus, their eligibility as part of a therapeutic strategy in cancer treatment.

Building blocks for bispecific and trispecific antibodies

Bispecific antibodies (BsAbs), which target two antigens or epitopes, incorporate the specificities and properties of two distinct monoclonal antibodies (mAbs) into a single molecule. As such, BsAbs can elicit synergistic activities and provide the capacity for enhanced therapeutic efficacy and/or safety compared to what can be achieved with conventional monospecific IgGs. There are many building block formats to generate BsAbs and Trispecific antibodies (TsAbs) based on combining the antigen recognition domains of monoclonal antibodies (mAbs). This review describes the many and varied antibody-based building blocks used to achieve multivalency and multispecificity. These diverse building blocks provide opportunities to tailor the design of BsAbs and TsAbs to match the desired applications.

Anti-drug antibodies to LMB-100 are enhanced by mAbs targeting OX40 and CTLA4 but not by mAbs targeting PD1 or PDL-1

LMB-100 is a recombinant immunotoxin being developed for cancer treatment that is composed of a Fab that binds to mesothelin and a portion of Pseudomonas exotoxin A. LMB-100 is in clinical trials for the treatment of mesothelioma and pancreatic cancer. To determine if check point modulating antibodies enhance the formation of anti-drug antibodies (ADA) against LMB-100, we treated mice with LMB-100 and four different immune modulating monoclonal antibodies that have different mechanisms of action; anti-CTLA4, anti-OX40, anti-PD-1 and anti-PDL-1. We found that anti-PD-1 and anti PDL-1 do not increase the formation of ADA, but anti-CTLA-4 and anti-OX-40 do increase the onset of ADA. These results indicate that combining anti-CTLA-4 and anti-OX-40 with antibodies and other protein-based therapeutics may enhance ADA formation in humans.

Targeting ubiquitin-proteasome pathway by natural, in particular polyphenols, anticancer agents: Lessons learned from clinical trials

The ubiquitin-proteasome pathway (UPP) is the main non-lysosomal proteolytic system responsible for degradation of most intracellular proteins, specifically damaged and regulatory proteins. The UPP is implicated in all aspects of the cellular metabolic networks including physiological or pathological conditions. Alterations in the components of the UPP can lead to stabilization of oncoproteins or augmented degradation of tumour suppressor favouring cancer appearance and progression. Polyphenols are natural compounds that can modulate proteasome activity or the expression of proteasome subunits. All together and due to the pleiotropic functions of UPP, there is a great interest in this proteasome system as a promising therapeutic target for the development of novel anti-cancer drugs. In the present review, the main features of the UPP and its implication in cancer development and progression are described, highlighting the importance of bioactive polyphenols that target the UPP as potential anti-cancer agents.

Potent CD4+ T cell-associated antitumor memory responses induced by trifunctional bispecific antibodies in combination with immune checkpoint inhibition

Combinatorial approaches of immunotherapy hold great promise for the treatment of malignant disease. Here, we examined the potential of combining an immune checkpoint inhibitor and trifunctional bispecific antibodies (trAbs) in a preclinical melanoma mouse model using surrogate antibodies of Ipilimumab and Catumaxomab, both of which have already been approved for clinical use. The specific binding arms of trAbs redirect T cells to tumor cells and trigger direct cytotoxicity, while the Fc region activates accessory cells eventually giving rise to a long-lasting immunologic memory. We show here that T cells redirected to tumor cells by trAbs strongly upregulate CTLA-4 expression in vitro and in vivo. This suggested that blocking of CTLA-4 in combination with trAb treatment enhances T-cell activation in a tumor-selective manner. However, when mice were challenged with melanoma cells and subsequently treated with antibodies, there was only a moderate beneficial effect of the combinatorial approach in vivo with regard to direct tumor destruction in comparison to trAb therapy alone. By contrast, a significantly improved vaccination effect was obtained by CTLA-4 blocking during trAb-dependent immunization. This resulted in enhanced rejection of melanoma cells given after pre-immunization. The improved immunologic memory induced by the combinatorial approach correlated with an increased humoral antitumor response as measured in the sera and an expansion of CD4⁺ memory T cells found in the spleens.

Curing tumor-bearing mice by shifting a Th2 to a Th1 anti-tumor response

Over the past several years remarkable therapeutic responses have been obtained with immunomodulatory monoclonal antibodies (mAbs), both in mice \cite{10,18,20,48,54,61} and human cancer patients \cite{1,3,14,28,30,39,80}. However, complete regressions and cures are infrequent and not predictable and some tumor types respond much worse than others. As an attempt to increase curability, we have investigated in mouse models the therapeutic efficacy of several mAb combinations, focusing on anti-PD-1/CTLA-4/CD137 and anti-PD-1/CTLA-4/CD137/CD19, and we have also combined mAbs with the chemotherapeutic drug cisplatin. Our data demonstrate an important contribution of anti-CD19 mAb to therapeutic efficacy, they show that intratumoral delivery of the mAbs is therapeutically more effective than systemic delivery, and that there is synergy when the mAbs are combined with cisplatin. In an attempt to improve predictability, we developed an in vitro model that may also be employed to search for novel immunomodulatory agents and combinations. This article reviews our data and discusses what is known about the underlying mechanisms.

Recent Advances in Targeting CD8 T-Cell Immunity for More Effective Cancer Immunotherapy

Recent advances in cancer treatment have emerged from new immunotherapies targeting T-cell inhibitory receptors, including cytotoxic T-lymphocyte associated antigen (CTLA)-4 and programmed cell death (PD)-1. In this context, anti-CTLA-4 and anti-PD-1 monoclonal antibodies have demonstrated survival benefits in numerous cancers, including melanoma and non-small-cell lung carcinoma. PD-1-expressing CD8⁺ T lymphocytes appear to play a major role in the response to these immune checkpoint inhibitors (ICI). Cytotoxic T lymphocytes (CTL) eliminate malignant cells through recognition by the T-cell receptor (TCR) of specific antigenic peptides presented on the surface of cancer cells by major histocompatibility complex class I/beta-2-microglobulin complexes, and through killing of target cells, mainly by releasing the content of secretory lysosomes containing perforin and granzyme B. T-cell adhesion molecules and, in particular, lymphocyte-function-associated antigen-1 and CD103 integrins, and their cognate ligands, respectively, intercellular adhesion molecule 1 and E-cadherin, on target cells, are involved in strengthening the interaction between CTL and tumor cells. Tumor-specific CTL have been isolated from tumor-infiltrating lymphocytes and peripheral blood lymphocytes (PBL) of patients with varied cancers. TCRβ-chain gene usage indicated that CTL identified in vitro selectively expanded in vivo at the tumor site compared to autologous PBL. Moreover, functional studies indicated that these CTL mediate human leukocyte antigen class I-restricted cytotoxic activity toward autologous tumor cells. Several of them recognize truly tumor-specific antigens encoded by mutated genes, also known as neoantigens, which likely play a key role in antitumor CD8 T-cell immunity. Accordingly, it has been shown that the presence of T lymphocytes directed toward tumor neoantigens is associated with patient response to immunotherapies, including ICI, adoptive cell transfer, and dendritic cell-based vaccines. These tumor-specific mutation-derived antigens open up new perspectives for development of effective second-generation therapeutic cancer vaccines.

TUSC2 Immunogene Therapy Synergizes with Anti-PD-1 through Enhanced Proliferation and Infiltration of Natural Killer Cells in Syngeneic Kras-Mutant Mouse Lung Cancer Models

Expression of the multikinase inhibitor encoded by the tumor suppressor gene TUSC2 (also known as FUS1) is lost or decreased in non-small cell lung carcinoma (NSCLC). TUSC2 delivered systemically by nanovesicles has mediated tumor regression in clinical trials. Because of the role of TUSC2 in regulating immune cells, we assessed TUSC2 efficacy on antitumor immune responses alone and in combination with anti-PD-1 in two Kras-mutant syngeneic mouse lung cancer models. TUSC2 alone significantly reduced tumor growth and prolonged survival compared with anti-PD-1. When combined, this effect was significantly enhanced, and correlated with a pronounced increases in circulating and splenic natural killer (NK) cells and CD8⁺ T cells, and a decrease in regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), and T-cell checkpoint receptors PD-1, CTLA-4, and TIM-3. TUSC2 combined with anti-PD-1 induced tumor infiltrating more than NK and CD8⁺ T cells and fewer MDSCs and Tregs than each agent alone, both in subcutaneous tumor and in lung metastases. NK-cell depletion abrogated the antitumor effect and Th1-mediated immune response of this combination, indicating that NK cells mediate TUSC2/anti-PD-1 synergy. Release of IL15 and IL18 cytokines and expression of the IL15Rα chain and IL18R1 were associated with NK-cell activation by TUSC2. Immune response-related gene expression in the tumor microenvironment was altered by combination treatment. These data provide a rationale for immunogene therapy combined with immune checkpoint blockade in the treatment of NSCLC. Cancer Immunol Res; 6(2); 163-77. ©2018 AACR.

Immunotherapy targeting 4-1BB: mechanistic rationale, clinical results, and future strategies

4-1BB (CD137, tumor necrosis factor receptor superfamily 9) is an inducible costimulatory receptor expressed on activated T and natural killer (NK) cells. 4-1BB ligation on T cells triggers a signaling cascade that results in upregulation of antiapoptotic molecules, cytokine secretion, and enhanced effector function. In dysfunctional T cells that have a decreased cytotoxic capacity, 4-1BB ligation demonstrates a potent ability to restore effector functions. On NK cells, 4-1BB signaling can increase antibody-dependent cell-mediated cytotoxicity. Agonistic monoclonal antibodies targeting 4-1BB have been developed to harness 4-1BB signaling for cancer immunotherapy. Preclinical results in a variety of induced and spontaneous tumor models suggest that targeting 4-1BB with agonist antibodies can lead to tumor clearance and durable antitumor immunity. Clinical trials of 2 agonist antibodies, urelumab and utomilumab, are ongoing. Despite initial signs of efficacy, clinical development of urelumab has been hampered by inflammatory liver toxicity at doses >1 mg/kg. Utomilumab has a superior safety profile, but is a less potent 4-1BB agonist relative to urelumab. Both antibodies have demonstrated promising results in patients with lymphoma and are being tested in combination therapy trials with other immunomodulatory agents. In an effort to optimally leverage 4-1BB-mediated immune activation, the next generation of 4-1BB targeting strategies attempts to decouple the observed antitumor efficacy from the on-target liver toxicity. Multiple therapeutics that attempt to restrict 4-1BB agonism to the tumor microenvironment and minimize systemic exposure have emerged. 4-1BB is a compelling target for cancer immunotherapy and future agents show great promise for achieving potent immune activation while avoiding limiting immune-related adverse events.

Administration of low-dose combination anti-CTLA4, anti-CD137, and anti-OX40 into murine tumor or proximal to the tumor draining lymph node induces systemic tumor regression

The delivery of immunomodulators directly into the tumor potentially harnesses the existing antigen, tumor-specific infiltrating lymphocytes, and antigen presenting cells. This can confer specificity and generate a potent systemic anti-tumor immune response with lower doses and less toxicity compared to systemic administration, in effect an in situ vaccine. Here, we test this concept using the novel combination of immunomodulators anti-CTLA4, -CD137, and -OX40. The triple combination administered intratumorally at low doses to one tumor of a dual tumor mouse model had dramatic local and systemic anti-tumor efficacy in lymphoma (A20) and solid tumor (MC38) models, consistent with an abscopal effect. The minimal effective dose was 10 μg each. The effect was dependent on CD8 T-cells. Intratumoral administration resulted in superior local and distant tumor control compared to systemic routes, supporting the in situ vaccine concept. In a single tumor A20 model, injection close to the tDLN resulted in similar efficacy as intratumoral and significantly better than targeting a non-tDLN, supporting the role of the tDLN as a viable immunotherapy target in addition to the tumor itself. Distribution studies confirmed expected concentration of antibodies in tumor and tDLN, in keeping with the anti-tumor results. Overall intratumoral or peri-tDLN administration of the novel combination of anti-CTLA4, anti-CD137, and anti-OX40, all agents in the clinic or clinical trials, demonstrates potent systemic anti-tumor effects. This immunotherapeutic combination is promising for future clinical development via both these safe and highly efficacious routes of administration.

Treg depletion potentiates checkpoint inhibition in claudin-low breast cancer

Claudin-low breast cancer is an aggressive subtype that confers poor prognosis and is found largely within the clinical triple-negative group of breast cancer patients. Here, we have shown that intrinsic and immune cell gene signatures distinguish the claudin-low subtype clinically as well as in mouse models of other breast cancer subtypes. Despite adaptive immune cell infiltration in claudin-low tumors, treatment with immune checkpoint inhibitory antibodies against cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed death receptor 1 (PD-1) were ineffective in controlling tumor growth. CD4+FoxP3+ Tregs represented a large proportion of the tumor-infiltrating lymphocytes (TILs) in claudin-low tumors, and Tregs isolated from tumor-bearing mice were able to suppress effector T cell responses. Tregs in the tumor microenvironment highly expressed PD-1 and were recruited partly through tumor generation of the chemokine CXCL12. Antitumor efficacy required stringent Treg depletion combined with checkpoint inhibition; delays in tumor growth were not observed using therapies that modestly diminished the number of Tregs in the tumor microenvironment. This study provides evidence that the recruitment of Tregs to the tumor microenvironment inhibits an effective antitumor immune response and highlights early Treg recruitment as a possible mechanism for the lack of response to immune checkpoint blockade antibodies in specific subtypes of cancer that are heavily infiltrated with adaptive immune cells.

Innate immune mediators in cancer: between defense and resistance

Chronic inflammation in the tumor microenvironment and evasion of the antitumor effector immune response are two of the emerging hallmarks required for oncogenesis and cancer progression. The innate immune system not only plays a critical role in perpetuating these tumor-promoting hallmarks but also in developing antitumor adaptive immune responses. Thus, understanding the dual role of the innate system in cancer immunology is required for the design of combined immunotherapy strategies able to tackle established tumors. Here, we review recent advances in the understanding of the role of cell populations and soluble components of the innate immune system in cancer, with a focus on complement, the adapter molecule Stimulator of Interferon Genes, natural killer cells, myeloid cells, and B cells.

The differentiation and plasticity of Tc17 cells are regulated by CTLA-4-mediated effects on STATs

As the blockade of inhibitory surface-molecules such as CTLA-4 on T cells has led to recent advances in antitumor immune therapy, there is great interest in identifying novel mechanisms of action of CD8⁺ T cells to evoke effective cytotoxic antitumor responses. Using in vitro and in vivo models, we investigated the molecular pathways underlying the CTLA-4-mediated differentiation of IL-17-producing CD8⁺ T cells (Tc17 cells) that strongly impairs cytotoxicity. Our studies demonstrate that Tc17 cells lacking CTLA-4 signaling have limited production of STAT3-target gene products such as IL-17, IL-21, IL-23R and RORγt. Upon re-stimulation with IL-12, these cells display fast downregulation of Tc17 hallmarks and acquire Tc1 characteristics such as IFNγ and TNF-α co-expression, which is known to correlate with tumor control. Indeed, upon adoptive transfer, these cells were highly efficient in the antigen-specific rejection of established OVA-expressing B16 melanoma in vivo. Mechanistically, in primary and re-stimulated Tc17 cells, STAT3 binding to the IL-17 promoter was strongly augmented by CTLA-4, associated with less binding of STAT5 and reduced relative activation of STAT1 which is known to block STAT3 activity. Inhibiting CTLA-4-induced STAT3 activity reverses enhancement of signature Tc17 gene products, rendering Tc17 cells susceptible to conversion to Tc1-like cells with enhanced cytotoxic potential. Thus, CTLA-4 critically shapes the characteristics of Tc17 cells by regulating relative STAT3 activation, which provides new perspectives to enhance cytotoxicity of antitumor responses.

Basis for molecular diagnostics and immunotherapy for esophageal cancer

INTRODUCTION

Esophageal cancer (EC) is an extremely aggressive neoplasm, diagnosed in about 17,000 Americans every year with a mortality rate of more than 80% within five years and a median overall survival of just 13 months. For decades, the go-to regimen for esophageal cancer patients has been the use of taxane and platinum-based chemotherapy regimens, which has yielded the field's most dire survival statistics. Areas covered: Combination immunotherapy and a more robust molecular diagnostic platform for esophageal tumors could improve patient management strategies and potentially extend lives beyond the current survival figures. Analyzing a panel of biomarkers including those affiliated with taxane and platinum resistance (ERCC1 and TUBB3) as well as immunotherapy effectiveness (PD-L1) would provide oncologists more information on how to optimize first-line therapy for EC. Expert commentary: Of the 12 FDA-approved therapies in EC, zero target the genome. A majority of the approved drugs either target or are effected by proteomic expression. Therefore, a broader understanding of diagnostic biomarkers could give more clarity and direction in treating esophageal cancer in concert with a greater use of immunotherapy.

CD137-CRDI is not necessary in the role of contacting its natural ligand

Immune checkpoint inhibitors result in impressive clinical responses and are expanding to treat a wide variety of tumors. One common problem is low responses from current clinical trials that only benefit a fraction of patients. One key promising direction is combination therapy to increase clinical benefit. CD137, a well-defined antitumor target, can cause strong co-stimulating activity and break immune tolerance. In this study, the role of CD137-CRDI (cysteine rich domain I) in the binding of CD137-CD137L was further investigated based on our previous work. The results revealed that CRDI-mediated limited CD137 assembly without relying on CD137L. Furthermore, CRDI was not involved in direct contact with CD137L in either mice or humans. Isolated mouse CRDII and human CRDII+CRDIII were proven to be the minimum unit for interface with their respective ligands. Fine-tuning of this signaling may improve CD137-targeting strategy.

Recent developments and future challenges in immune checkpoint inhibitory cancer treatment

PURPOSE OF REVIEW

In this review, we focus on the recent findings and future challenges in cancer treatment with immune checkpoint inhibitors.

RECENT FINDINGS

Major progress has been made in recent years as the first immune checkpoint inhibitors are approved by the US Food and Drug Administration for the treatment of cancer patients. Anticytotoxic T-lymphocyte-associated protein 4 and antiprogrammed death protein 1/programmed death-ligand 1 (PD-L1) monoclonal antibodies are being extensively studied in many different tumor types, often showing impressive response rates, but also a typical serious toxicity profile in the form of auto-immunity. Unfortunately, it is not yet possible to prevent or predict these immune-related adverse events. Studies on mutational load, neo-epitopes, lactate dehydrogenase, PD-L1 expression, and T-cell infiltration suggest that these markers are correlating with efficacy, but have not yet reached the status of a validated biomarker for checkpoint inhibitors. Other immune checkpoints are being investigated and new checkpoint inhibitors are on the brink of being evaluated in clinical trials.

SUMMARY

The main challenge for the near future will be to predict efficacy of immune checkpoint blockade and to predict and prevent immune-related adverse events. More research should be done in order to find potential biomarkers that predict treatment response and/or toxicity; the optimal administration route, dosage, and frequency; and possible combinations of therapies that have an added or synergetic effect.

Deciphering CD137 (4-1BB) signaling in T-cell costimulation for translation into successful cancer immunotherapy

CD137 (4-1BB, TNF-receptor superfamily 9) is a surface glycoprotein of the TNFR family which can be induced on a variety of leukocyte subsets. On T and NK cells, CD137 is expressed following activation and, if ligated by its natural ligand (CD137L), conveys polyubiquitination-mediated signals via TNF receptor associated factor 2 that inhibit apoptosis, while enhancing proliferation and effector functions. CD137 thus behaves as a bona fide inducible costimulatory molecule. These functional properties of CD137 can be exploited in cancer immunotherapy by systemic administration of agonist monoclonal antibodies, which increase anticancer CTLs and enhance NK-cell-mediated antibody-dependent cell-mediated cytotoxicity. Reportedly, anti-CD137 mAb and adoptive T-cell therapy strongly synergize, since (i) CD137 expression can be used to select the T cells endowed with the best activities against the tumor, (ii) costimulation of the lymphocyte cultures to be used in adoptive T-cell therapy can be done with CD137 agonist antibodies or CD137L, and (iii) synergistic effects upon coadministration of T cells and antibodies are readily observed in mouse models. Furthermore, the signaling cytoplasmic tail of CD137 is a key component of anti-CD19 chimeric antigen receptors that are used to redirect T cells against leukemia and lymphoma in the clinic. Ongoing phase II clinical trials with agonist antibodies and the presence of CD137 sequence in these successful chimeric antigen receptors highlight the importance of CD137 in oncoimmunology.

Immune Mechanisms Are Major Players in Cancer

Vaccination with sipuleucel-T produced IgG antibodies to secondary prostatic carcinoma antigens and prolonged survival in some patients, and assaying for antibodies may provide prognostic information and identify new vaccine targets. Additional approaches to improve T-cell responses are needed to improve the clinical efficacy. See related article by GuhaThakurta et al., p. 3619.

Evolving synergistic combinations of targeted immunotherapies to combat cancer

Immunotherapy has now been clinically validated as an effective treatment for many cancers. There is tremendous potential for synergistic combinations of immunotherapy agents and for combining immunotherapy agents with conventional cancer treatments. Clinical trials combining blockade of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) may serve as a paradigm to guide future approaches to immuno-oncology combination therapy. In this Review, we discuss progress in the synergistic design of immune-targeting combination therapies and highlight the challenges involved in tailoring such strategies to provide maximal benefit to patients.

Inhibition of Tumor Growth and Immunomodulatory Effects of Flavonoids and Scutebarbatines of Scutellaria barbata D. Don in Lewis-Bearing C57BL/6 Mice

Immunomodulatory effect has been found to be an important therapeutic measure for immune responses against cancer. In this study, we evaluated the inhibition of Scutellaria barbata D. Don (SB), an anti-inflammatory and an antitumor Chinese herb, including flavonoids and scutebarbatines on tumor growth and its immunomodulatory effects in vivo. HPLC and LC/MS/MS methods were conducted for the analysis of flavonoids and scutebarbatines in SB. Lewis-bearing C57BL/6 mice model was established and tumor volume was evaluated by high frequency color ultrasound experiment. ELISA and western blot analysis were performed for the determination of immunomodulatory factors. SB treatment at the dose of 10, 6.67, and 3.33 g crude drug/kg/d significantly inhibited tumor growth of Lewis-bearing C57BL/6 mice with the inhibition rates of 44.41 ± 5.44%, 33.56 ± 4.85%, and 27.57 ± 4.96%, respectively. More importantly, the spleen and thymus indexes were increased remarkably by SB treatment. SB could decrease IL-17, IL-10, FOXP3, TGF-β1, RORγt, and IL-6 levels whereas it could increase remarkably IL-2 and IFN-γ levels. Our results demonstrated that SB could inhibit tumor growth in vivo through regulating immune function in tumor-bearing mice and suggested that the immunomodulatory function of SB had a potential therapeutic effect in lung cancer.

Trial Watch: Immunomodulatory monoclonal antibodies for oncological indications

Immunomodulatory monoclonal antibodies (mAbs) differ from their tumor-targeting counterparts because they exert therapeutic effects by directly interacting with soluble or (most often) cellular components of the immune system. Besides holding promise for the treatment of autoimmune and inflammatory disorders, immunomodulatory mAbs have recently been shown to constitute a potent therapeutic weapon against neoplastic conditions. One class of immunomodulatory mAbs operates by inhibiting safeguard systems that are frequently harnessed by cancer cells to establish immunological tolerance, the so-called "immune checkpoints." No less than 3 checkpoint-blocking mAbs have been approved worldwide for use in oncological indications, 2 of which during the past 12 months. These molecules not only mediate single-agent clinical activity in patients affected by specific neoplasms, but also significantly boost the efficacy of several anticancer chemo-, radio- or immunotherapies. Here, we summarize recent advances in the development of checkpoint-blocking mAbs, as well as of immunomodulatory mAbs with distinct mechanisms of action.

Immunomodulatory antibody therapy of cancer: the closer, the better

Immune checkpoint blockade therapies have demonstrated promising therapeutic effects; however, clinical outcomes are variable, with only a subgroup of cancer patients achieving durable complete responses. New therapeutic strategies, including local administration of immunomodulatory antibodies, have been considered as better routes for improving the overall efficacy of antibody-based therapy.