Anti-Folate Receptor-α IgE but not IgG Recruits Macrophages to Attack Tumors via TNFα/MCP-1 Signaling

Physiochemical and functional evaluation of the first-in-class anti-cancer IgE antibody drug, MOv18, through process development and good manufacturing practice production

Antibodies used for cancer therapy are monoclonal IgGs, but tumor-targeting IgE antibodies have shown enhanced effector cell potency against cancer in preclinical models. Research-grade recombinant IgE antibodies have been generated and studied for several decades. The recent Phase 1 clinical trial of the first-in-class MOv18 IgE, however, necessitated the inaugural process development and scaled manufacture of a recombinant IgE to clinical quality standards. During the process development and scaled Good Manufacturing Practice production, we demonstrate the retention of glycosylation state, biophysical profile, and functional characteristics of MOv18 IgE, including Fc-mediated mast cell degranulation and tumor cell killing. Assessment of manufacturing parameters shows expected pH, purity, concentration, and stability properties, as well as below threshold levels of known biological manufacturing contaminants. We confirm the suitability of the pipeline described for generating intact, functionally active, clinical-grade material for this novel therapeutic class as an Investigational Medicinal Product (IMP), with comparable characteristics to the original research-grade antibody. Furthermore, we screened patient blood ex vivo for potential type I hypersensitivity reaction to MOv18 IgE, using the basophil activation test, to identify patients not predicted to be hypersensitive to MOv18 IgE administration. This study supports the production of functionally active clinical grade (IMP) recombinant IgE and paves the way for the development of a new therapeutic antibody class for a range of antigenic specificities and disease settings.

Folate receptor alpha for cancer therapy: an antibody and antibody-drug conjugate target coming of age

Folate receptor alpha (FRα) has long been the focus of therapeutics development in oncology across several solid tumors, notably ovarian, lung, and subsets of breast cancers. Its multiple roles in cellular metabolism and carcinogenesis and tumor-specific overexpression relative to normal tissues render FRα an attractive target for biological therapies. Here we review the biological significance, expression distribution, and characteristics of FRα as a highly promising and now established therapy target. We discuss the ongoing development of FRα-targeting antibodies and antibody-drug conjugates (ADCs), the first of which has been approved for the treatment of ovarian cancer, providing the impetus for heightened research and therapy development. Novel insights into the tumor microenvironment, advances in antibody engineering to enhance immune-mediated effects, the emergence of ADCs, and several studies of anti-FRα agents combined with chemotherapy, targeted and immune therapy are offering new perspectives and treatment possibilities. Hence, we highlight key translational research and discuss several preclinical studies and clinical trials of interest, with an emphasis on agents and therapy combinations with potential to change future clinical practice.

Hyperinflammatory repolarisation of ovarian cancer patient macrophages by anti-tumour IgE antibody, MOv18, restricts an immunosuppressive macrophage:Treg cell interaction

Ovarian cancer is the most lethal gynaecological cancer and treatment options remain limited. In a recent first-in-class Phase I trial, the monoclonal IgE antibody MOv18, specific for the tumour-associated antigen Folate Receptor-α, was well-tolerated and preliminary anti-tumoural activity observed. Pre-clinical studies identified macrophages as mediators of tumour restriction and pro-inflammatory activation by IgE. However, the mechanisms of IgE-mediated modulation of macrophages and downstream tumour immunity in human cancer remain unclear. Here we study macrophages from patients with epithelial ovarian cancers naive to IgE therapy. High-dimensional flow cytometry and RNA-seq demonstrate immunosuppressive, FcεR-expressing macrophage phenotypes. Ex vivo co-cultures and RNA-seq interaction analyses reveal immunosuppressive associations between patient-derived macrophages and regulatory T (Treg) cells. MOv18 IgE-engaged patient-derived macrophages undergo pro-inflammatory repolarisation ex vivo and display induction of a hyperinflammatory, T cell-stimulatory subset. IgE reverses macrophage-promoted Treg cell induction to increase CD8+ T cell expansion, a signature associated with improved patient prognosis. On-treatment tumours from the MOv18 IgE Phase I trial show evidence of this IgE-driven immune signature, with increased CD68+ and CD3+ cell infiltration. We demonstrate that IgE induces hyperinflammatory repolarised states of patient-derived macrophages to inhibit Treg cell immunosuppression. These processes may collectively promote immune activation in ovarian cancer patients receiving IgE therapy.

Fc-mediated immune stimulating, pro-inflammatory and antitumor effects of anti-HER2 IgE against HER2-expressing and trastuzumab-resistant tumors

BACKGROUND

Anti-human epidermal growth factor receptor 2 (HER2) IgG1-based antibody therapies significantly improve cancer prognosis, yet intrinsic or acquired resistance to fragment antigen-binding (Fab)-mediated direct effects commonly occurs. Most resistant tumors retain antigen expression and therefore remain potentially targetable with anti-HER2 therapies that promote immune-mediated responses. Tumor-antigen-specific IgE class antibodies can mediate powerful immune cell-mediated effects against different cancers and have been shown to activate IgE Fc receptor-expressing monocytes. We previously reported the engineering of a trastuzumab-equivalent anti-HER2 IgE antibody and showed early evidence of Fc-mediated cancer cell-targeting effects. In the present study, we evaluated the anti-tumoral functions of two anti-HER2 IgEs, trastuzumab and pertuzumab IgE.

METHODS

In vitro functionality of the two anti-HER2 antibodies was assessed by HER2 phosphorylation and ligand-independent viability assays, as well as basophil (RBL-SX38) degranulation, antibody-dependent cellular cytotoxicity/antibody-dependent cellular phagocytosis(ADCC/ADCP) assays and primary monocyte stimulation assays. The potential to trigger a hypersensitivity type I reaction was investigated using the basophil activation test (BAT). anti-tumoral efficacy was assessed in two humanized HER2+, trastuzumab-resistant models in vivo. Changes in the tumor microenvironment were assessed by flow cytometry or bulk RNA sequencing.

RESULTS

We demonstrate the anti-tumoral and immunostimulatory functions of two anti-HER2 IgEs derived from variable region sequences of the clinically available trastuzumab and pertuzumab IgG1 antibodies. IgE engagement of monocytes via the Fc region induced tumor cell cytotoxicity and a pro-inflammatory shift with upregulation of immune-stimulatory CD40, CD80 and CD86, and downregulation of scavenger CD163, cell surface molecules. This was accompanied by enhanced pro-inflammatory tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β cytokine production. The absence of basophil activation by anti-HER2 IgEs ex vivo in whole blood points to potentially safe administration in humans. In two trastuzumab-resistant HER2+ tumor xenograft models in immunodeficient mice reconstituted with human immune cells, the trastuzumab-equivalent anti-HER2 IgE restricted tumor growth. Treatment was associated with enriched classical (CD14+CD16-) monocyte and lower alternatively-activated (CD163+CD206+) macrophage infiltration, and higher densities of activated CD4+ (CD127loCD25hi) T cells and favorable effector T cell(Teff) to regulatory T cell (Treg) ratios in tumors.

CONCLUSION

Collectively, anti-HER2 IgE maintains Fab-mediated antitumor activity, induces Fc-mediated effects against HER2-expressing tumor cells, and stimulates remodeling of the immune microenvironment in tumors to promote pro-inflammatory cell phenotypes which could translate to improved outcomes for patients.

Association of immunoglobulin E levels with glioma risk and survival

BACKGROUND

Previous epidemiological studies have reported an association of serum immunoglobulin E (IgE) levels with reduced glioma risk, but the association between IgE and glioma prognosis has not been characterized. This study aimed to examine how sex, tumor subtype, and IgE class modulate the association of serum IgE levels with glioma risk and survival.

METHODS

We conducted a case-control study using participants from the University of California San Francisco Adult Glioma Study (1997-2010). Serum IgE levels for total, respiratory, and food allergy were measured in adults diagnosed with glioma (n = 1319) and cancer-free control individuals (n = 1139) matched based on age, sex, and race and ethnicity. Logistic regression was adjusted for patient demographics to assess the association between IgE levels and glioma risk. Multivariable Cox regression adjusted for patient-specific and tumor-specific factors compared survival between the elevated and normal IgE groups. All statistical tests were 2-sided.

RESULTS

Elevated total IgE was associated with reduced risk of IDH wild-type glioma (risk ratio [RR] = 0.78, 95% CI = 0.71 to 0.86) and IDH-mutant glioma (RR = 0.73, 95% CI = 0.63 to 0.85). In multivariable Cox regression, positive respiratory IgE was associated with improved survival for IDH wild-type glioma (RR = 0.79, 95% CI = 0.67 to 0.93). The reduction in mortality risk was statistically significant in female individuals only (RR = 0.75, 95% CI = 0.57 to 0.98), with an improvement in median survival of 6.9 months (P < .001).

CONCLUSION

Elevated serum IgE was associated with improved prognosis for IDH wild-type glioma, with a more pronounced protective effect in female than male individuals, which has implications for the future study of IgE-based immunotherapies for glioma.

An IgE antibody targeting HER2 identified by clonal selection restricts breast cancer growth via immune-stimulating activities

BACKGROUND

Tumor-targeting IgE antibodies have elicited potent tumor-restricting effects by recruiting immune effector mechanisms. However, a dedicated platform for the generation, selection and evaluation of novel IgEs based on target antigen recognition and functional profiles has not been reported.

METHODS

By establishing an IgE class antibody therapeutic design platform to allow selection of lead candidates, we generated a panel of IgEs recognising the human epidermal growth factor receptor 2 (HER2), overexpressed in 15-20% of breast cancers. From 1840 phage display-generated variable region sequences panned against HER2, we engineered 30 full length IgE antibodies. We selected three clones based on biophysical properties, reactivity to HER2 + cancer cells, epitope reactivity and Fc-mediated anti-tumor profiles in vitro. Clones with cross-reactivity to rat HER2 were selected to allow functional evaluations in a fully immunocompetent syngeneic HER2 + rat breast cancer model.

RESULTS

IgE antibodies induced degranulation and antibody-dependent cellular cytotoxicity against human and rat HER2-expressing tumor cells in vitro. IgE antibody 26 demonstrated anti-tumor activity in a syngeneic HER2 + rat model, and a human HER2 + breast cancer xenograft model in mice reconstituted with human immune cells. Treatment was associated with enhanced immune cell infiltration and pro-inflammatory immune signatures, and downregulated cancer progression signaling pathways, in the tumor microenvironment.

CONCLUSIONS

This study pioneers the design and generation of anti-HER2 IgE lead antibody candidates with immune-stimulating and tumor-restricting effects. The present work may pave the way for antibody engineering therapeutic opportunities for challenging-to-treat HER2-expressing cancers.

Systematic mutational analysis reveals an essential role of N275 in IgE stability

Therapeutic antibodies have predominantly been IgG-based. However, the ongoing clinical trial of MOv18 IgE has highlighted the potential of using IgE antibodies in cancer therapy. While extensive studies targeting IgG glycosylation resulted in a rational basis for the development of enhanced biotherapeutics, IgE glycosylation remains an area with limited analyses. Previous studies on the role of IgE glycosylation present conflicting data with one study emphasizing the importance of N275 and T277 residues for FcεRI binding whereas another asserts the nonsignificance of IgE glycosylation in receptor interaction. While existing literature underscores the significance of glycans at the N275 position for binding to FcεR1 receptor and initiation of anaphylaxis, the role of other IgE glycosylation sites in folding or receptor binding remains elusive. This study systematically investigates the functional significance of N-linked glycosylation sites in the heavy chain of IgE which validates the pivotal role of N275 residue in IgE secretion and stability. Replacement of this asparagine to non-amine group moieties does not affect IgE function in vitro, yet substitution with aspartic acid compromises antibody yield. The deglycosylated IgE variant exhibits superior efficacy, challenging the conventional importance of glycosylation for effector function. In summary, our study unveils an intricate relationship between N-glycosylation sites and the structural-functional dynamics of IgE antibodies. Furthermore, it offers novel insights into the IgE scaffold, paving the way for the development of more effective and stable IgE-based therapeutics.

Deciphering Folate Receptor alphaGene Expression and mRNA Signatures in Ovarian Cancer: Implications for Precision Therapies

Antibody-drug conjugates targeting folate receptor alpha (FRα) are a promising treatment for platinum-resistant ovarian cancer (OC) with high FRα expression. Challenges persist in accurately assessing FRα expression levels. Our study aimed to better elucidate FRα gene expression and identify mRNA signatures in OC. We pooled OC gene expression data from 16 public datasets, encompassing 1832 OC and 30 normal ovarian tissues. Additional data included DNA copy number and methylation data from TCGA and protein data from 363 cancer cell lines from the Broad Institute Cancer Cell Line Encyclopedia. FOLR1 mRNA expression was significantly correlated with protein expression in pan-cancer cell lines and ovarian cancer cell lines. FOLR1 expression was higher in OC samples than in normal ovarian tissues (OR = 3.88, p = 6.97 × 10-12). Patients with high FOLR1 expression were more likely to be diagnosed with serous histology, FIGO stage III-IV, and high-grade tumors; however, nearly similar percentages of patients with low FOLR1 expression were also diagnosed with these features. FOLR1 mRNA expression was not correlated with platinum sensitivity or complete surgery, nor with prognosis. However, we identified a 187-gene signature associated with high FOLR1 expression that was significantly associated with improved survival (HR = 0.71, p = 1.18 × 10-6), independently from clinicopathological features. We identified a gene expression signature correlated to high FRα expression and OC prognosis, which may be used to refine therapeutic strategies targeting FRα in OC. These findings warrant validation in larger cohorts.

Secretory Nogo-B regulates Th2 differentiation in the lung cancer microenvironment

Nogo-B, a ubiquitously expressed member of the reticulon family, plays an important role in maintaining endoplasmic reticulum (ER) structure, regulating protein folding, and calcium homeostasis. In this study, we demonstrate that Nogo-B expression and secretion are upregulated in lung cancer and correlate to overall survival. Nogo-B is secreted by various cells, particularly lung cancer cells. ER stress and phosphorylation at serine 107 can induce Nogo-B secretion. Secretory Nogo-B suppresses the differentiation of Th2 cells and the release of type 2 cytokines, thus influencing the anti-tumor effects of Th2-related immune cells, including IgE+B cell class switching and eosinophil activation.

Therapeutic Monoclonal Antibodies against Cancer: Present and Future

A series of monoclonal antibodies with therapeutic potential against cancer have been generated and developed. Ninety-one are currently used in the clinics, either alone or in combination with chemotherapeutic agents or other antibodies, including immune checkpoint antibodies. These advances helped to coin the term personalized medicine or precision medicine. However, it seems evident that in addition to the current work on the analysis of mechanisms to overcome drug resistance, the use of different classes of antibodies (IgA, IgE, or IgM) instead of IgG, the engineering of the Ig molecules to increase their half-life, the acquisition of additional effector functions, or the advantages associated with the use of agonistic antibodies, to allow a broad prospective usage of precision medicine successfully, a strategy change is required. Here, we discuss our view on how these strategic changes should be implemented and consider their pros and cons using therapeutic antibodies against cancer as a model. The same strategy can be applied to therapeutic antibodies against other diseases, such as infectious or autoimmune diseases.

A Fully Human IgE Specific for CD38 as a Potential Therapy for Multiple Myeloma

Multiple myeloma (MM) is an incurable malignancy of plasma cells and the second most common hematologic malignancy in the United States. Although antibodies in clinical cancer therapy are generally of the IgG class, antibodies of the IgE class have attractive properties as cancer therapeutics, such as their high affinity for Fc receptors (FcεRs), the low serum levels of endogenous IgE allowing for less competition for FcR occupancy, and the lack of inhibitory FcRs. Importantly, the FcεRs are expressed on immune cells that elicit antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), and/or antigen presentation such as mast cells, eosinophils, macrophages, and dendritic cells. We now report the development of a fully human IgE targeting human CD38 as a potential MM therapy. We targeted CD38 given its high and uniform expression on MM cells. The novel anti-CD38 IgE, expressed in mammalian cells, is properly assembled and secreted, exhibits the correct molecular weight, binds antigen and the high affinity FcεRI, and induces degranulation of FcεRI expressing cells in vitro and also in vivo in transgenic BALB/c mice expressing human FcεRIα. Moreover, the anti-CD38 IgE induces ADCC and ADCP mediated by monocytes/macrophages against human MM cells (MM.1S). Importantly, the anti-CD38 IgE also prolongs survival in a preclinical disseminated xenograft mouse model using SCID-Beige mice and human MM.1S cells when administered with human peripheral blood mononuclear cells (PBMCs) as a source of monocyte effector cells. Our results suggest that anti-CD38 IgE may be effective in humans bearing MM and other malignancies expressing CD38.

Allergic Rhinitis and Cancer Risk: A Two-Sample Mendelian Randomization Study

Background: There is increasing evidence that allergic rhinitis (AR) is associated with cancer. However, these results are inconsistent. Because of common risk factors, there may be reverse causality and confounding factors that affect our understanding of the relationship between AR and cancer. We aimed to explore the role of AR in cancer development using Mendelian randomization (MR) analysis. Materials and Methods: We performed a two-sample MR analysis using summary data from genome-wide association studies (GWAS). Single nucleotide polymorphisms (SNPs) strongly associated with AR (or hay fever) were used as instrumental variables, mainly using the inverse variance weighted analysis method, supplemented by MR Egger, maximum likelihood, weighted media, and penalized weighted media for MR analysis. Sensitivity analyses included heterogeneity and horizontal pleiotropy; and leave-one-out analyses were performed to test the robustness of our results. Results: MR analysis revealed no evidence of a causal relationship between AR and any of the examined cancers (all p > 0.05). The results using five different analytical approaches were similar. Sensitivity analyses showed no evidence of heterogeneity nor horizontal pleiotropy. According to the leave-one-out sensitivity analyses, no individual SNP was significantly influencing the causal effect of AR on cancers. Conclusions: These findings do not provide evidence to support that AR has a large impact on the risk of eight common cancers in the European population. However, we cannot rule out a very minor effect of AR on cancer. Further large-scale studies are necessary to validate our findings.

Safety and anti-tumour activity of the IgE antibody MOv18 in patients with advanced solid tumours expressing folate receptor-alpha: a phase I trial

All antibodies approved for cancer therapy are monoclonal IgGs but the biology of IgE, supported by comparative preclinical data, offers the potential for enhanced effector cell potency. Here we report a Phase I dose escalation trial (NCT02546921) with the primary objective of exploring the safety and tolerability of MOv18 IgE, a chimeric first-in-class IgE antibody, in patients with tumours expressing the relevant antigen, folate receptor-alpha. The trial incorporated skin prick and basophil activation tests (BAT) to select patients at lowest risk of allergic toxicity. Secondary objectives were exploration of anti-tumour activity, recommended Phase II dose, and pharmacokinetics. Dose escalation ranged from 70 μg-12 mg. The most common toxicity of MOv18 IgE is transient urticaria. A single patient experienced anaphylaxis, likely explained by detection of circulating basophils at baseline that could be activated by MOv18 IgE. The BAT assay was used to avoid enrolling further patients with reactive basophils. The safety profile is tolerable and maximum tolerated dose has not been reached, with evidence of anti-tumour activity observed in a patient with ovarian cancer. These results demonstrate the potential of IgE therapy for cancer.

Anti-cancer pro-inflammatory effects of an IgE antibody targeting the melanoma-associated antigen chondroitin sulfate proteoglycan 4

Outcomes for half of patients with melanoma remain poor despite standard-of-care checkpoint inhibitor therapies. The prevalence of the melanoma-associated antigen chondroitin sulfate proteoglycan 4 (CSPG4) expression is ~70%, therefore effective immunotherapies directed at CSPG4 could benefit many patients. Since IgE exerts potent immune-activating functions in tissues, we engineer a monoclonal IgE antibody with human constant domains recognizing CSPG4 to target melanoma. CSPG4 IgE binds to human melanomas including metastases, mediates tumoricidal antibody-dependent cellular cytotoxicity and stimulates human IgE Fc-receptor-expressing monocytes towards pro-inflammatory phenotypes. IgE demonstrates anti-tumor activity in human melanoma xenograft models engrafted with human effector cells and is associated with enhanced macrophage infiltration, enriched monocyte and macrophage gene signatures and pro-inflammatory signaling pathways in the tumor microenvironment. IgE prolongs the survival of patient-derived xenograft-bearing mice reconstituted with autologous immune cells. No ex vivo activation of basophils in patient blood is measured in the presence of CSPG4 IgE. Our findings support a promising IgE-based immunotherapy for melanoma.

Allergic airway inflammation delays glioblastoma progression and reinvigorates systemic and local immunity in mice

BACKGROUND

Numerous patient-based studies have highlighted the protective role of immunoglobulin E-mediated allergic diseases on glioblastoma (GBM) susceptibility and prognosis. However, the mechanisms behind this observation remain elusive. Our objective was to establish a preclinical model able to recapitulate this phenomenon and investigate the role of immunity underlying such protection.

METHODS

An immunocompetent mouse model of allergic airway inflammation (AAI) was initiated before intracranial implantation of mouse GBM cells (GL261). RAG1-KO mice served to assess tumor growth in a model deficient for adaptive immunity. Tumor development was monitored by MRI. Microglia were isolated for functional analyses and RNA-sequencing. Peripheral as well as tumor-associated immune cells were characterized by flow cytometry. The impact of allergy-related microglial genes on patient survival was analyzed by Cox regression using publicly available datasets.

RESULTS

We found that allergy establishment in mice delayed tumor engraftment in the brain and reduced tumor growth resulting in increased mouse survival. AAI induced a transcriptional reprogramming of microglia towards a pro-inflammatory-like state, uncovering a microglia gene signature, which correlated with limited local immunosuppression in glioma patients. AAI increased effector memory T-cells in the circulation as well as tumor-infiltrating CD4⁺ T-cells. The survival benefit conferred by AAI was lost in mice devoid of adaptive immunity.

CONCLUSION

Our results demonstrate that AAI limits both tumor take and progression in mice, providing a preclinical model to study the impact of allergy on GBM susceptibility and prognosis, respectively. We identify a potentiation of local and adaptive systemic immunity, suggesting a reciprocal crosstalk that orchestrates allergy-induced immune protection against GBM.

Folate receptor alpha in ovarian cancer tissue and patient serum is associated with disease burden and treatment outcomes

BACKGROUND

Survival rates for ovarian cancer remain poor, and monitoring and prediction of therapeutic response may benefit from additional markers. Ovarian cancers frequently overexpress Folate Receptor alpha (FRα) and the soluble receptor (sFRα) is measurable in blood. Here we investigated sFRα as a potential biomarker.

METHODS

We evaluated sFRα longitudinally, before and during neo-adjuvant, adjuvant and palliative therapies, and tumour FRα expression status by immunohistrochemistry. The impact of free FRα on the efficacy of anti-FRα treatments was evaluated by an antibody-dependent cellular cytotoxicity assay.

RESULTS

Membrane and/or cytoplasmic FRα staining were observed in 52.7% tumours from 316 ovarian cancer patients with diverse histotypes. Circulating sFRα levels were significantly higher in patients, compared to healthy volunteers, specifically in patients sampled prior to neoadjuvant and palliative treatments. sFRα was associated with FRα cell membrane expression in the tumour. sFRα levels decreased alongside concurrent tumour burden in patients receiving standard therapies. High concentrations of sFRα partly reduced anti-FRα antibody tumour cell killing, an effect overcome by increased antibody doses.

CONCLUSIONS

sFRα may present a non-invasive marker for tumour FRα expression, with the potential for monitoring patient response to treatment. Larger, prospective studies should evaluate FRα for assessing disease burden and response to systemic treatments.

Comorbidities of Chronic Urticaria: A glimpse into a complex relationship

Chronic Urticaria (CU) is a chronic inflammatory, predominantly mast cell-driven disease, characterized by the development of wheals and/or angioedema for more than 6 weeks. It affects approximately 1%-5% of the total population worldwide and imposes a substantial burden on health-related quality of life, significantly affecting patients' daily life. The economic impact on the health system is also not negligible, with an estimated cost per patient per year of approximately 2.000 $ in the United States. Although the underlying pathophysiology is not fully explored, autoimmune mechanisms have been proposed, including type I ("autoallergy" by means of autoantibodies to self-antigens) and type IIb (autoimmunity). Atopic, autoimmune, and psychiatric disorders are prevalent comorbidities in both children and adults with Chronic Spontaneous Urticaria (CSU). Although malignancies, cardiovascular diseases and other comorbidities have also been reported as associated diseases in patients with CSU, data remain scarce. It is still unknown whether the aforementioned comorbidities share common pathophysiological mechanisms with specific endotypes of CSU. The current review aims to overview current data on comorbidities of CU, and furthermore to comment on the potential linked pathways underlying these diseases.

Influencing tumor-associated macrophages in malignant melanoma with monoclonal antibodies

The application of monoclonal antibodies (mAbs) for the treatment of melanoma has significantly improved the clinical management of this malignancy over the last decade. Currently approved mAbs for melanoma enhance T cell effector immune responses by blocking immune checkpoint molecules PD-L1/PD-1 and CTLA-4. However, more than half of patients do not benefit from treatment. Targeting the prominent myeloid compartment within the tumor microenvironment, and in particular the ever-abundant tumor-associated macrophages (TAMs), may be a promising strategy to complement existing therapies and enhance treatment success. TAMs are a highly diverse and plastic subset of cells whose pro-tumor properties can support melanoma growth, angiogenesis and invasion. Understanding of their diversity, plasticity and multifaceted roles in cancer forms the basis for new promising TAM-centered treatment strategies. There are multiple mechanisms by which macrophages can be targeted with antibodies in a therapeutic setting, including by depletion, inhibition of specific pro-tumor properties, differential polarization to pro-inflammatory states and enhancement of antitumor immune functions. Here, we discuss TAMs in melanoma, their interactions with checkpoint inhibitor antibodies and emerging mAbs targeting different aspects of TAM biology and their potential to be translated to the clinic.

Heterogeneity and Functions of Tumor-Infiltrating Antibody Secreting Cells: Lessons from Breast, Ovarian, and Other Solid Cancers

Simple Summary

B cells are gaining increasing recognition as important contributors to the tumor microenvironment, influencing, positively or negatively, tumor growth, patient survival, and response to therapies. Antibody secreting cells (ASCs) constitute a variable fraction of tumor-infiltrating B cells in most solid tumors, and they produce tumor-specific antibodies that can drive distinct immune responses depending on their isotypes and specificities. In this review, we discuss the current knowledge of the heterogeneity of ASCs infiltrating solid tumors and how both their canonical and noncanonical functions shape antitumor immunity, with a special emphasis on breast and ovarian cancers.

Abstract

Neglected for a long time in cancer, B cells and ASCs have recently emerged as critical actors in the tumor microenvironment, with important roles in shaping the antitumor immune response. ASCs indeed exert a major influence on tumor growth, patient survival, and response to therapies. The mechanisms underlying their pro- vs. anti-tumor roles are beginning to be elucidated, revealing the contributions of their secreted antibodies as well as of their emerging noncanonical functions. Here, concentrating mostly on ovarian and breast cancers, we summarize the current knowledge on the heterogeneity of tumor-infiltrating ASCs, we discuss their possible local or systemic origin in relation to their immunoglobulin repertoire, and we review the different mechanisms by which antibody (Ab) subclasses and isoforms differentially impact tumor cells and anti-tumor immunity. We also discuss the emerging roles of cytokines and other immune modulators produced by ASCs in cancer. Finally, we propose strategies to manipulate the tumor ASC compartment to improve cancer therapies.

A human IgE bispecific antibody shows potent cytotoxic capacity mediated by monocytes

The generation of bispecific antibodies (bsAbs) targeting two different antigens opens a new level of specificity and, compared to mAbs, improved clinical efficacy in cancer therapy. Currently, the different strategies for development of bsAbs primarily focus on IgG isotypes. Nevertheless, in comparison to IgG isotypes, IgE has been shown to offer superior tumor control in preclinical models. Therefore, in order to combine the promising potential of IgE molecules with increased target selectivity of bsAbs, we developed dual tumor-associated antigen-targeting bispecific human IgE antibodies. As proof of principle, we used two different pairing approaches - knobs-into-holes and leucine zipper-mediated pairing. Our data show that both strategies were highly efficient in driving bispecific IgE formation, with no undesired pairings observed. Bispecific IgE antibodies also showed a dose-dependent binding to their target antigens, and cell bridging experiments demonstrated simultaneous binding of two different antigens. As antibodies mediate a major part of their effector functions through interaction with Fc receptors (FcRs) expressed on immune cells, we confirmed FcεR binding by inducing in vitro mast cell degranulation and demonstrating in vitro and in vivo monocyte-mediated cytotoxicity against target antigen-expressing Chinese hamster ovary cells. Moreover, we demonstrated that the IgE bsAb construct was significantly more efficient in mediating antibody-dependent cell toxicity than its IgG1 counterpart. In conclusion, we describe the successful development of first bispecific IgE antibodies with superior antibody-dependent cell toxicity-mediated cell killing in comparison to IgG bispecific antibodies. These findings highlight the relevance of IgE-based bispecific antibodies for clinical application.

Harnessing the Anti-Tumor Mediators in Mast Cells as a New Strategy for Adoptive Cell Transfer for Cancer

The emergence of cancer immunotherapies utilizing adoptive cell transfer (ACT) continues to be one of the most promising strategies for cancer treatment. Mast cells (MCs) which occur throughout vascularized tissues, are most commonly associated with Type I hypersensitivity, bind immunoglobin E (IgE) with high affinity, produce anti-cancer mediators such as tumor necrosis factor alpha (TNF-α) and granulocyte macrophage colony-stimulating factor (GM-CSF), and generally populate the tumor microenvironments. Yet, the role of MCs in cancer pathologies remains controversial with evidence for both anti-tumor and pro-tumor effects. Here, we review the studies examining the role of MCs in multiple forms of cancer, provide an alternative, MC-based hypothesis underlying the mechanism of therapeutic tumor IgE efficacy in clinical trials, and propose a novel strategy for using tumor-targeted, IgE-sensitized MCs as a platform for developing new cellular cancer immunotherapies. This autologous MC cancer immunotherapy could have several advantages over current cell-based cancer immunotherapies and provide new mechanistic strategies for cancer therapeutics alone or in combination with current approaches.

AllergoOncology: Role of immune cells and immune proteins

Background

Immune cells and immune proteins play a pivotal role in host responses to pathogens, allergens and cancer. Understanding the crosstalk between allergic response and cancer, immune surveillance, immunomodulation, role of immunoglobulin E (IgE)‐mediated functions and help to develop novel therapeutic strategies. Allergy and oncology show two opposite scenarios: whereas immune tolerance is desired in allergy, it is detrimental in cancer.

Aim

The current review provides an update on the role of immune cells and immune proteins in allergy and cancer fields.

Methods

Authors investigated the role of relevant immunological markers and the correlation with cancer progression or cancer suppression.

Results

Activated immune cells such as macrophages ‘M1’, dendritic cells (DCs), innate lymphoid cells (ILC2), NK cells, Th1, follicular T helper cells (TFH), TCD8+, B lymphocytes and eosinophils have inhibitory effects on tumourigenesis, while tolerogenic cells such as macrophages ‘M2,’ tolerogenic DCs, ILC3, T and B regulatory lymphocytes appear to favour carcinogenesis. Mastocytes and alarmins can have both effects. RIgE antibodies and CCCL5 chemokine have an anticancer role, whereas IgG4, free light chains, Il‐10, TGF‐β, lipocalin‐2, CCL1 chemokine promote cancer progression. Fundamental is also the contribution of epigenetic changes regulated by the microRNA in cancer progression.

Conclusion

This knowledge represents the key to developing new anticancer therapies.

Clinical and Translational Significance of Basophils in Patients with Cancer

Despite comprising a very small proportion of circulating blood leukocytes, basophils are potent immune effector cells. The high-affinity receptor for IgE (FcɛRI) is expressed on the basophil cell surface and powerful inflammatory mediators such as histamine, granzyme B, and cytokines are stored in dense cytoplasmic granules, ready to be secreted in response to a range of immune stimuli. Basophils play key roles in eliciting potent effector functions in allergic diseases and type 1 hypersensitivity. Beyond allergies, basophils can be recruited to tissues in chronic and autoimmune inflammation, and in response to parasitic, bacterial, and viral infections. While their activation states and functions can be influenced by Th2-biased inflammatory signals, which are also known features of several tumor types, basophils have received little attention in cancer. Here, we discuss the presence and functional significance of basophils in the circulation of cancer patients and in the tumor microenvironment (TME). Interrogating publicly available datasets, we conduct gene expression analyses to explore basophil signatures and associations with clinical outcomes in several cancers. Furthermore, we assess how basophils can be harnessed to predict hypersensitivity to cancer treatments and to monitor the desensitization of patients to oncology drugs, using assays such as the basophil activation test (BAT).

Folate Metabolism in Hepatocellular Carcinoma. What Do We Know So Far?

Cancer cells are characterized by accelerated proliferation and an outstanding adaptation of their metabolic pathways to meet energy demands. The folate cycle, also known as folate metabolism or one-carbon metabolism, through enzymatic interconversions, provides metabolites necessary for nucleotide synthesis, methylation, and reduction power, helping to maintain the high rate of proliferation; therefore, the study of this metabolic pathway is of great importance in the study of cancer. Moreover, multiple enzymes involved in this cycle have been implicated in different types of cancer, corroborating the cell's adaptations under this pathology. During the last decade, nonalcoholic fatty liver disease has emerged as the leading etiology related to the rise in the incidence and deaths of hepatocellular carcinoma. Specifically, cholesterol accumulation has been a determinant promoter of tumor formation, with solid evidence that an enriched-cholesterol diet plays a crucial role in accelerating the development of an aggressive subtype of hepatocellular carcinoma compared to other models. In this review, we will discuss the most recent findings to understand the contribution of folate metabolism to cancer cells and tumor microenvironment while creating a link between the dynamics given by cholesterol and methylenetetrahydrofolate dehydrogenase 1-like, a key enzyme of the cycle located in the mitochondrial compartment.

Identification of Immune-Related Key Genes in Ovarian Cancer Based on WGCNA

Background: Ovarian cancer (OV) is a fatal gynecologic malignancy and has poor survival rate in women over the age of forty. In our study, we aimed to identify genes related to immune microenvironment regulations and explore genes associated with OV prognosis. Methods: The RNA-seq data of GDC TCGA Ovarian Cancer cohort of 376 patients was retrieved from website. Weighted gene co-expression network analysis (WGCNA) and ESTIMATE algorithm were applied to identify the key genes associated with the immune scores. The correlation between key genes and 22 immune cell types were estimated by using CIBERSORT algorithms. Results: WGCNA showed that the pink module was most correlated with the immune score. Seven of 14 key genes (FCRL3, IFNG, KCNA3, LY9, PLA2G2D, THEMIS, and TRAT1) were significantly associated with the OS of OV patients. Correlation analysis showed our key genes positively related to M1 macrophages, CD8 T cells, plasma cells, regulatory T (Treg) cells and activated memory CD4 T cells, and negatively related to naive CD4 T cells, M0 macrophages, activated dendritic cells (DCs) and memory B cells. Kaplan-Meier survival analysis showed that lower abundances of neutrophils and higher abundances of M1 macrophages, plasma cells, T cells gamma delta (γδT) cells and follicular helper T (Tfh) cells predicted better OV prognosis. Conclusion: Forteen key genes related to the immune infiltrating of OV were identified, and seven of them were significantly related to prognosis. These key genes have potential roles in tumor infiltrating immune cells differentiation and proliferation. This study provided potential prognostic markers and immunotherapy targets for OV.

IgE-Based Therapeutic Combination Enhances Antitumor Response in Preclinical Models of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) represents 3% of all cancer cases and 7% of all cancer deaths in the United States. Late diagnosis and inadequate response to standard chemotherapies contribute to an unfavorable prognosis and an overall 5-year survival rate of less than 10% in PDAC. Despite recent advances in tumor immunology, tumor-induced immunosuppression attenuates the immunotherapy response in PDAC. To date, studies have focused on IgG-based therapeutic strategies in PDAC. With the recent interest in IgE-based therapies in multiple solid tumors, we explored the MUC1-targeted IgE potential against pancreatic cancer. Our study demonstrates the notable expression of FceRI (receptor for IgE antibody) in tumors from PDAC patients. Our study showed that administration of MUC1 targeted-IgE (mouse/human chimeric anti-MUC1.IgE) antibody at intermittent levels in combination with checkpoint inhibitor (anti-PD-L1) and TLR3 agonist (PolyICLC) induces a robust antitumor response that is dependent on NK and CD8 T cells in pancreatic tumor-bearing mice. Subsequently, our study showed that the antigen specificity of the IgE antibody plays a vital role in executing the antitumor response as nonspecific IgE, induced by ovalbumin (OVA), failed to restrict tumor growth in pancreatic tumor-bearing mice. Utilizing the OVA-induced allergic asthma-PDAC model, we demonstrate that allergic phenotype induced by OVA cannot restrain pancreatic tumor growth in orthotopic tumor-bearing mice. Together, our data demonstrate the novel tumor protective benefits of tumor antigen-specific IgE-based therapeutics in a preclinical model of pancreatic cancer, which can open new avenues for future clinical interventions.

Macrophages in ovarian cancer and their interactions with monoclonal antibody therapies

The unmet clinical need for effective treatments in ovarian cancer has yet to be addressed using monoclonal antibodies (mAbs), which have largely failed to overcome tumour-associated immunosuppression, restrict cancer growth, and significantly improve survival. In recent years, experimental mAb design has moved away from solely targeting ovarian tumours and instead sought to modulate the wider tumour microenvironment (TME). Tumour-associated macrophages (TAMs) may represent an attractive therapeutic target for mAbs in ovarian cancer due to their high abundance and close proximity to tumour cells and their active involvement in facilitating several pro-tumoural processes. Moreover, the expression of several antibody crystallisable fragment (Fc) receptors and broad phenotypic plasticity of TAMs provide opportunities to modulate TAM polarisation using mAbs to promote anti-tumoural phenotypes. In this review, we discuss the role of TAMs in ovarian cancer TME and the emerging strategies to target the contributions of these cells in tumour progression through the rationale design of mAbs.

Remodeling of the tumor microenvironment via disrupting Blimp1+ effector Treg activity augments response to anti-PD-1 blockade

BACKGROUND

Accumulation of Foxp3⁺ regulatory T (Treg) cells in the tumor often represents an important mechanism for cancer immune evasion and a critical barrier to anti-tumor immunity and immunotherapy. Many tumor-infiltrating Treg cells display an activated phenotype and express the transcription factor Blimp1. However, the specific impact of these Blimp1⁺ Treg cells and their follicular regulatory T (T_FR) cell subset on tumor and the underlying mechanisms of action are not yet well-explored.

METHODS

Various transplantable tumor models were established in immunocompetent wild-type mice and mice with a Foxp3-specific ablation of Blimp1. Tumor specimens from patients with metastatic melanoma and TCGA datasets were analyzed to support the potential role of Treg and T_FR cells in tumor immunity. In vitro culture assays and in vivo adoptive transfer assays were used to understand how Treg, T_FR cells and antibody responses influence tumor control. RNA sequencing and NanoString analysis were performed to reveal the transcriptome of tumor-infiltrating Treg cells and tumor cells, respectively. Finally, the therapeutic effects of anti-PD-1 treatment combined with the disruption of Blimp1⁺ Treg activity were evaluated.

RESULTS

Blimp1⁺ Treg and T_FR cells were enriched in the tumors, and higher tumoral T_FR signatures indicated increased risk of melanoma metastasis. Deletion of Blimp1 in Treg cells resulted in impaired suppressive activity and a reprogramming into effector T-cells, which were largely restricted to the tumor-infiltrating Treg population. This destabilization combined with increased anti-tumor effector cellular responses, follicular helper T-cell expansion, enhanced tumoral IgE deposition and activation of macrophages secondary to dysregulated T_FR cells, remodeled the tumor microenvironment and delayed tumor growth. The increased tumor immunogenicity with MHC upregulation improved response to anti-PD-1 blockade. Mechanistically, Blimp1 enforced intratumoral Treg cells with a unique transcriptional program dependent on Eomesodermin (Eomes) expression; deletion of Eomes in Blimp1-deficient Treg cells restored tumor growth and attenuated anti-tumor immunity.

CONCLUSIONS

These findings revealed Blimp1 as a new critical regulator of tumor-infiltrating Treg cells and a potential target for modulating Treg activity to treat cancer. Our study has also revealed two FCERIA-containing immune signatures as promising diagnostic or prognostic markers for melanoma patients.

In vivo trafficking of a tumor-targeting IgE antibody: molecular imaging demonstrates rapid hepatobiliary clearance compared to IgG counterpart

IgE antibodies elicit powerful immune responses, recruiting effector cells to tumors more efficiently and with greater cytotoxicity than IgG antibodies. Consequently, IgE antibodies are a promising alternative to conventional IgG-based therapies in oncology (AllergoOncology). As the pharmacokinetics of IgE antibodies are less well understood, we used molecular imaging in mice to compare the distribution and elimination of IgE and IgG antibodies targeting the human tumor-associated antigen chondroitin sulfate proteoglycan 4 (CSPG4). Anti-CSPG4 IgE and IgG1 antibodies with human Fc domains were radiolabeled with 111In. CSPG4-expressing A375 human melanoma xenografts implanted in NOD-scid IL2rg-/- mice were also engrafted with human immune cells by intravenous administration. 111In-anti-CSPG4 antibodies were administered intravenously. Their distribution was determined by single-photon emission computed tomography (SPECT) and ex vivo gamma-counting over 120 h. SPECT imaging was conducted from 0 to 60 min after antibody administration to precisely measure the early phase of IgE distribution. 111In-labeled anti-CSPG4 IgG and IgE showed serum stability in vitro of >92% after 5 days. In A375 xenograft-bearing mice, anti-CSPG4 IgE showed much faster blood clearance and higher accumulation in the liver compared to anti-CSPG4 IgG. However, tumor-to-blood and tumor-to-muscle ratios were similar between the antibody isotypes and higher compared with a non-tumor-targeting isotype control IgE. IgE excretion was much faster than IgG. In non-tumor-bearing animals, early SPECT imaging revealed a blood clearance half-life of 10 min for IgE. Using image-based quantification, we demonstrated that the blood clearance of IgE is much faster than that of IgG while the two isotypes showed comparable tumor-to-blood ratios.

Insights from IgE Immune Surveillance in Allergy and Cancer for Anti-Tumour IgE Treatments

IgE, the predominant antibody class of the allergic response, is known for its roles in protecting against parasites; however, a growing body of evidence indicates a significant role for IgE and its associated effector cells in tumour immunosurveillance, highlighted by the field of AllergoOncology and the successes of the first-in-class IgE cancer therapeutic MOv18. Supporting this concept, substantial epidemiological data ascribe potential roles for IgE, allergy, and atopy in protecting against specific tumour types, with a corresponding increased cancer risk associated with IgE immunodeficiency. Here, we consider how epidemiological data in combination with functional data reveals a complex interplay of IgE and allergy with cancer, which cannot be explained solely by one of the existing conventional hypotheses. We furthermore discuss how, in turn, such data may be used to inform future therapeutic approaches, including the clinical management of different patient groups. With epidemiological findings highlighting several high-risk cancer types protected against by high IgE levels, it is possible that use of IgE-based therapeutics for a range of malignant indications may offer efficacy to complement that of established IgG-class antibodies.

Development of a novel multi-functional integrated bioconjugate that effectively targets K-Ras mutant pancreatic cancer

Folate receptor (FR) overexpression occurs in a variety of cancers, including pancreatic cancer. In addition, enhanced macropinocytosis exists in K-Ras mutant pancreatic cancer. Furthermore, the occurrence of intensive desmoplasia causes a hypoxic microenvironment in pancreatic cancer. In this study, a novel FR-directed, macropinocytosis-enhanced, and highly cytotoxic bioconjugate folate (F)-human serum albumin (HSA)-apoprotein of lidamycin (LDP)-active enediyne (AE) derived from lidamycin was designed and prepared. F-HSA-LDP-AE consisted of four moieties: F, HSA, LDP, and AE. F-HSA-LDP presented high binding efficiency with the FR and pancreatic cancer cells. Its uptake in wild-type cells was more extensive than in K-Ras mutant-type cells. By in vivo optical imaging, F-HSA-LDP displayed prominent tumor-specific biodistribution in pancreatic cancer xenograft-bearing mice, showing clear and lasting tumor localization for 360 h. In the MTT assay, F-HSA-LDP-AE demonstrated potent cytotoxicity in three types of pancreatic cancer cell lines. It also induced apoptosis and caused G2/M cell cycle arrest. F-HSA-LDP-AE markedly suppressed the tumor growth of AsPc-1 pancreatic cancer xenografts in athymic mice. At well-tolerated doses of 0.5 and 1 mg/kg, (i.v., twice), the inhibition rates were 91.2% and 94.8%, respectively (P<0.01). The results of this study indicate that the F-HSA-LDP multi-functional bioconjugate might be effective for treating K-Ras mutant pancreatic cancer.

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We designed and generated a folate receptor-targeted and macropinocytosis-enhanced recombinant protein conjugate.

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F-HSA-LDP displayed highly specific biodistribution and long-lasting tumor accumulation in pancreatic cancer cells.

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F-HSA-LDP-AE induced apoptosis and G2/M cell cycle arrest and markedly suppressed the growth of pancreatic cancer cells.

Immunotherapy using IgE or CAR T cells for cancers expressing the tumor antigen SLC3A2

Background

Cancer immunotherapy with monoclonal antibodies and chimeric antigen receptor (CAR) T cell therapies can benefit from selection of new targets with high levels of tumor specificity and from early assessments of efficacy and safety to derisk potential therapies.

Methods

Employing mass spectrometry, bioinformatics, immuno-mass spectrometry and CRISPR/Cas9 we identified the target of the tumor-specific SF-25 antibody. We engineered IgE and CAR T cell immunotherapies derived from the SF-25 clone and evaluated potential for cancer therapy.

Results

We identified the target of the SF-25 clone as the tumor-associated antigen SLC3A2, a cell surface protein with key roles in cancer metabolism. We generated IgE monoclonal antibody, and CAR T cell immunotherapies each recognizing SLC3A2. In concordance with preclinical and, more recently, clinical findings with the first-in-class IgE antibody MOv18 (recognizing the tumor-associated antigen Folate Receptor alpha), SF-25 IgE potentiated Fc-mediated effector functions against cancer cells in vitro and restricted human tumor xenograft growth in mice engrafted with human effector cells. The antibody did not trigger basophil activation in cancer patient blood ex vivo, suggesting failure to induce type I hypersensitivity, and supporting safe therapeutic administration. SLC3A2-specific CAR T cells demonstrated cytotoxicity against tumor cells, stimulated interferon-γ and interleukin-2 production in vitro. In vivo SLC3A2-specific CAR T cells significantly increased overall survival and reduced growth of subcutaneous PC3-LN3-luciferase xenografts. No weight loss, manifestations of cytokine release syndrome or graft-versus-host disease, were detected.

Conclusions

These findings identify efficacious and potentially safe tumor-targeting of SLC3A2 with novel immune-activating antibody and genetically modified cell therapies.

Isotype selection for antibody-based cancer therapy

The clinical application of monoclonal antibodies (mAbs) has revolutionized the field of cancer therapy, as it has enabled the successful treatment of previously untreatable types of cancer. Different mechanisms play a role in the anti-tumour effect of mAbs. These include blocking of tumour-specific growth factor receptors or of immune modulatory molecules as well as complement and cell-mediated tumour cell lysis. Thus, for many mAbs, Fc-mediated effector functions critically contribute to the efficacy of treatment. As immunoglobulin (Ig) isotypes differ in their ability to bind to Fc receptors on immune cells as well as in their ability to activate complement, they differ in the immune responses they activate. Therefore, the choice of antibody isotype for therapeutic mAbs is dictated by its intended mechanism of action. Considering that clinical efficacy of many mAbs is currently achieved only in subsets of patients, optimal isotype selection and Fc optimization during antibody development may represent an important step towards improved patient outcome. Here, we discuss the current knowledge of the therapeutic effector functions of different isotypes and Fc-engineering strategies to improve mAbs application.

In vivo safety profile of a CSPG4-directed IgE antibody in an immunocompetent rat model

IgE monoclonal antibodies hold great potential for cancer therapy. Preclinical in vivo systems, particularly those in which the antibody recognizes the host species target antigen and binds to cognate Fc receptors, are often the closest approximation to human exposure and represent a key challenge for evaluating the safety of antibody-based therapies. We sought to develop an immunocompetent rat system to assess the safety of a rodent anti-tumor IgE, as a surrogate for the human therapeutic candidate. We generated a rat IgE against the human tumor-associated antigen chondroitin sulfate proteoglycan 4 (CSPG4) and cross-reactive for the rat antigen. We analyzed CSPG4 distribution in normal rat and human tissues and investigated the in vivo safety of the antibody by monitoring clinical signs and molecular biomarkers after systemic administration to immunocompetent rats. Human and rat CSPG4 expression in normal tissues were comparable. Animals receiving antibody exhibited transient mild to moderate adverse events accompanied by mild elevation of serum tryptase, but not of angiotensin II or cytokines implicated in allergic reactions or cytokine storm. In the long term, repeated antibody administration was well tolerated, with no changes in animal body weight, liver and kidney functions or blood cell counts. This model provides preclinical support for the safety profiling of IgE therapeutic antibodies. Due to the comparable antigen tissue distribution in human and rat, this model may also comprise an appropriate tool for proof-of-concept safety evaluations of different treatment approaches targeting CSPG4.

Classification of ovarian cancer associated with BRCA1 mutations, immune checkpoints, and tumor microenvironment based on immunogenomic profiling

Background

Ovarian cancer is a highly fatal gynecological malignancy and new, more effective treatments are needed. Immunotherapy is gaining attention from researchers worldwide, although it has not proven to be consistently effective in the treatment of ovarian cancer. We studied the immune landscape of ovarian cancer patients to improve the efficacy of immunotherapy as a treatment option.

Methods

We obtained expression profiles, somatic mutation data, and clinical information from The Cancer Genome Atlas. Ovarian cancer was classified based on 29 immune-associated gene sets, which represented different immune cell types, functions, and pathways. Single-sample gene set enrichment (ssGSEA) was used to quantify the activity or enrichment levels of the gene sets in ovarian cancer, and the unsupervised machine learning method was used sort the classifications. Our classifications were validated using Gene Expression Omnibus datasets.

Results

We divided ovarian cancer into three subtypes according to the ssGSEA score: subtype 1 (low immunity), subtype 2 (median immunity), and subtype 3 (high immunity). Most tumor-infiltrating immune cells and immune checkpoint molecules were upgraded in subtype 3 compared with those in the other subtypes. The tumor mutation burden (TMB) was not significantly different among the three subtypes. However, patients with BRCA1 mutations were consistently detected in subtype 3. Furthermore, most immune signature pathways were hyperactivated in subtype 3, including T and B cell receptor signaling pathways, PD-L1 expression and PD-1 checkpoint pathway the NF-κB signaling pathway, Th17 cell differentiation and interleukin-17 signaling pathways, and the TNF signaling pathway.

Conclusion

Ovarian cancer subtypes that are based on immune biosignatures may contribute to the development of novel therapeutic treatment strategies for ovarian cancer.

IgE Activates Monocytes from Cancer Patients to Acquire a Pro-Inflammatory Phenotype

IgE contributes to host-protective functions in parasitic and bacterial infections, often by monocyte and macrophage recruitment. We previously reported that monocytes contribute to tumour antigen-specific IgE-mediated tumour growth restriction in rodent models. Here, we investigate the impact of IgE stimulation on monocyte response, cellular signalling, secretory and tumour killing functions. IgE cross-linking on human monocytes with polyclonal antibodies to mimic formation of immune complexes induced upregulation of co-stimulatory (CD40, CD80, CD86), and reduced expression of regulatory (CD163, CD206, MerTK) monocyte markers. Cross-linking and tumour antigen-specific IgE antibody-dependent cellular cytotoxicity (ADCC) of cancer cells by cancer patient-derived monocytes triggered release of pro-inflammatory mediators (TNFα, MCP-1, IL-10, CXCL-10, IL-1β, IL-6, IL-23). High intratumoural gene expression of these mediators was associated with favourable five-year overall survival in ovarian cancer. IgE cross-linking of trimeric FcεRI on monocytes stimulated the phosphorylation of intracellular protein kinases widely reported to be downstream of mast cell and basophil tetrameric FcεRI signalling. These included recently-identified FcεRI pathway kinases Fgr, STAT5, Yes and Lck, which we now associate with monocytes. Overall, anti-tumour IgE can potentiate pro-inflammatory signals, and prime tumour cell killing by human monocytes. These findings will inform the development of IgE monoclonal antibody therapies for cancer.

IgE Antibodies against Cancer: Efficacy and Safety

Immunoglobulin E (IgE) antibodies are well known for their role in allergic diseases and for contributions to antiparasitic immune responses. Properties of this antibody class that mediate powerful effector functions may be redirected for the treatment of solid tumours. This has led to the rise of a new class of therapeutic antibodies to complement the armamentarium of approved tumour targeting antibodies, which to date are all IgG class. The perceived risk of type I hypersensitivity reactions following administration of IgE has necessitated particular consideration in the development of these therapeutic agents. Here, we bring together the properties of IgE antibodies pivotal to the hypothesis for superior antitumour activity compared to IgG, observations of in vitro and in vivo efficacy and mechanisms of action, and a focus on the safety considerations for this novel class of therapeutic agent. These include in vitro studies of potential hypersensitivity, selection of and observations from appropriate in vivo animal models and possible implications of the high degree of glycosylation of IgE. We also discuss the use of ex vivo predictive and monitoring clinical tools, as well as the risk mitigation steps employed in, and the preliminary outcomes from, the first-in-human clinical trial of a candidate anticancer IgE therapeutic.

Tumor-associated macrophages: Role in the pathological process of tumorigenesis and prospective therapeutic use (Review)

The aim of the present study was to evaluate the current body of knowledge regarding tumor-associated macrophages (TAMs) and their potential use in antitumor therapy, based on their role in the pathological process of tumorigenesis. For this purpose, a critical analysis of published data and summarization of the findings available from original studies, focusing on the role of TAMs in the pathological process, and their potential therapeutic application was performed. Promising key avenues of research were identified in this field. The following issues seem the most promising and thus worth further investigation: i) The process of M1/M2 macrophage polarization, macrophage characteristics at intermediate polarization steps and their role in the tumor process; ii) determining the conditions necessary for transitions between the M1 and M2 macrophage phenotypes and the role of signals from the microenvironment in this process; iii) cause-and-effect associations between the quantity and quality of macrophages, and the prognosis and outcome of the pathological process; iv) modulation of macrophages and stimulation of their phagocytic activity with drugs; v) targeted vector-based systems for drug delivery to macrophages; and vi) targeted drug delivery systems with macrophages as carriers, thus potentially combining chemotherapy and immunotherapy.

Filling the Antibody Pipeline in Allergy: PIPE Cloning of IgE, IgG1 and IgG4 against the Major Birch Pollen Allergen Bet v 1

Birch pollen allergy is among the most prevalent pollen allergies in Northern and Central Europe. This IgE-mediated disease can be treated with allergen immunotherapy (AIT), which typically gives rise to IgG antibodies inducing tolerance. Although the main mechanisms of allergen immunotherapy (AIT) are known, questions regarding possible Fc-mediated effects of IgG antibodies remain unanswered. This can mainly be attributed to the unavailability of appropriate tools, i.e., well-characterised recombinant antibodies (rAbs). We hereby aimed at providing human rAbs of several classes for mechanistic studies and as possible candidates for passive immunotherapy. We engineered IgE, IgG1, and IgG4 sharing the same variable region against the major birch pollen allergen Bet v 1 using Polymerase Incomplete Primer Extension (PIPE) cloning. We tested IgE functionality and IgG blocking capabilities using appropriate model cell lines. In vitro studies showed IgE engagement with FcεRI and CD23 and Bet v 1-dependent degranulation. Overall, we hereby present fully functional, human IgE, IgG1, and IgG4 sharing the same variable region against Bet v 1 and showcase possible applications in first mechanistic studies. Furthermore, our IgG antibodies might be useful candidates for passive immunotherapy of birch pollen allergy.

Harnessing Therapeutic IgE Antibodies to Re-educate Macrophages against Cancer

Currently, IgG is the only class of antibodies employed for cancer therapy. However, harnessing the unique biological properties of a different class ( e.g., IgE) could engender potent effector cell activation, and unleash previously untapped immune mechanisms against cancer. IgE antibodies are best known for pathogenic roles in allergic diseases and for protective effector functions against parasitic infestation, often mediated by IgE Fc receptor-expressing macrophages. Notably, IgE possess a very high affinity for cognate Fc receptors expressed by tumor-associated macrophages (TAMs). This paper reviews pre-clinical studies, which indicate control of cancer growth by tumor antigen-specific IgE that recruit and re-educate TAMs towards activated profiles. The clinical development harnessing the antitumor potential of recombinant IgE antibodies in cancer patients is also discussed.

Antibodies specific for disease-associated antigens (DAA) expressed in non-malignant diseases reveal potential new tumor-associated antigens (TAA) for immunotherapy or immunoprevention

Immune responses to a large number of mutated and non-mutated tumor antigens have been studied in an attempt to unravel the highly complex immune response to cancer. Better understanding of both the effectors and the targets of successful immunosurveillance can inform various immunotherapeutic approaches, which can strengthen or replace natural immunosurveillance that a tumor has managed to escape. In this review we highlight targets of antibodies generated in the context of diseases other than cancer, such as asthma, allergies, autoimmune disorders, inflammation and infections, where the antibody presence correlates either with an increased or a reduced lifetime risk of cancer. We focus on their target antigens, self-molecules abnormally expressed on diseased cells or cross-reactive with exogenous antigens and found on cancer cells as tumor associated antigens (TAA). We refer to them as disease-associated antigens (DAA). We review 4 distinct categories of antibodies according to their target DAA, their origin and their reported impact on cancer risk: natural antibodies, autoantibodies, long-term memory antibodies and allergy-associated antibodies. Increased understanding and focus on their specific targets could enable a more rational choice of antigens for both therapeutic and preventative cancer vaccines and other more effective and less toxic cancer immunotherapies.

In Planta Glycan Engineering and Functional Activities of IgE Antibodies

Human immunoglobulin E (IgE) is the most extensively glycosylated antibody isotype so glycans attached to the seven N-glycosites (NGS) in its Fab and Fc domains may modulate its functions. However, targeted modification of glycans in multiply glycosylated proteins remains a challenge. Here, we applied an in vivo approach that allows the manipulation of IgE N-glycans, using a trastuzumab equivalent IgE (HER2-IgE) as a model. Taking advantage of plant inherent features, i.e., synthesis of largely homogeneous complex N-glycans and susceptibility to glycan engineering, we generated targeted glycoforms of HER2-IgE largely resembling those found in serum IgE. Plant-derived HER2-IgE exhibited N-glycans terminating with GlcNAc, galactose or sialic acid, lacking, or carrying core fucose and xylose. We were able to not only modulate the five NGSs naturally decorated with complex N-glycans, but to also induce targeted glycosylation at the usually unoccupied NGS6, thus increasing the overall glycosylation content of HER2-IgE. Recombinant human cell-derived HER2-IgE exhibited large N-glycan heterogeneity. All HER2-IgE variants demonstrated glycosylation-independent binding to the target antigen and the high affinity receptor FcεRI, and subsequent similar capacity to trigger mast cell degranulation. In contrast, binding to the low affinity receptor CD23 (FcεRII) was modulated by the glycan profile, with increased binding to IgE variants with glycans terminating with GlcNAc residues. Here we offer an efficient in planta approach to generate defined glycoforms on multiply glycosylated IgE, allowing the precise exploration of glycosylation-dependent activities.

AllergoOncology: High innate IgE levels are decisive for the survival of cancer-bearing mice

Background

Atopics have a lower risk for malignancies, and IgE targeted to tumors is superior to IgG in fighting cancer. Whether IgE-mediated innate or adaptive immune surveillance can confer protection against tumors remains unclear.

Objective

We aimed to investigate the effects of active and passive immunotherapy to the tumor-associated antigen HER-2 in three murine models differing in Epsilon-B-cell-receptor expression affecting the levels of expressed IgE.

Methods

We compared the levels of several serum specific anti-HER-2 antibodies (IgE, IgG1, IgG2a, IgG2b, IgA) and the survival rates in low-IgE ΔM1M2 mice lacking the transmembrane/cytoplasmic domain of Epsilon-B-cell-receptors expressing reduced IgE levels, high-IgE KN1 mice expressing chimeric Epsilon-Gamma1-B-cell receptors with 4-6-fold elevated serum IgE levels, and wild type (WT) BALB/c. Prior engrafting mice with D2F2/E2 mammary tumors overexpressing HER-2, mice were vaccinated with HER-2 or vehicle control PBS using the Th2-adjuvant Al(OH)₃ (active immunotherapy), or treated with the murine anti-HER-2 IgG1 antibody 4D5 (passive immunotherapy).

Results

Overall, among the three strains of mice, HER-2 vaccination induced significantly higher levels of HER-2 specific IgE and IgG1 in high-IgE KN1, while low-IgE ΔM1M2 mice had higher IgG2a levels. HER-2 vaccination and passive immunotherapy prolonged the survival in tumor-grafted WT and low-IgE ΔM1M2 strains compared with treatment controls; active vaccination provided the highest benefit. Notably, untreated high-IgE KN1 mice displayed the longest survival of all strains, which could not be further extended by active or passive immunotherapy.

Conclusion

Active and passive immunotherapies prolong survival in wild type and low-IgE ΔM1M2 mice engrafted with mammary tumors. High-IgE KN1 mice have an innate survival benefit following tumor challenge.

IgE re-programs alternatively-activated human macrophages towards pro-inflammatory anti-tumoural states

BACKGROUND

Antibody Fc-driven engagement of macrophages is critical for evoking cellular activation and effector functions and influencing tumour-associated macrophage (TAM) recruitment. We previously reported that IgE class antibodies promote restriction of cancer growth in rodent models associated with significant TAM infiltration. However, the human macrophage-associated IgE-Fc Receptor (FcεR) axis remains unexplored. We investigated the effects of anti-tumour IgE stimulation on human macrophage activation.

METHODS

Human blood monocyte-differentiated quiescent (M0), classically-(M1) and alternatively-(M2) activated macrophages were crosslinked with IgE and polyclonal antibodies to mimic immune complex formation. We examined surface marker expression, cytokine secretion, protein kinase phosphorylation and gene expression in IgE-stimulated macrophages and IgE antibody-dependent macrophage-mediated cytotoxicity (ADCC) against tumour cells.

FINDINGS

A proportion (40%) of M2 and (<20%) M0 and M1 macrophages expressed the high-affinity IgE receptor FcεRI. IgE crosslinking triggered upregulation of co-stimulatory CD80, increased TNFα, IFNγ, IL-1β, IL-12, IL-10, IL-13, CXCL9, CXCL11 and RANTES secretion by M0 and M2 and additionally enhanced MCP-1 by M2 macrophages. IgE-stimulated M1 macrophages retained secretion of pro-inflammatory cytokines. IgE crosslinking enhanced the FcεRI-dependent signalling pathway, including phosphorylation of the Lyn kinase, ERK1/2 and p38 in M2 macrophages and upregulated Lyn gene expression by M1 and M2 macrophages. Anti-tumour IgE engendered ADCC of cancer cells by all macrophage subsets.

INTERPRETATION

IgE can engage and re-educate alternatively-activated macrophages towards pro-inflammatory phenotypes and prime all subsets to mediate anti-tumour functions. This points to IgE-mediated cascades with potential to activate immune stroma and may be significant in the clinical development of strategies targeting tumour-resident macrophages.

Immune mediator expression signatures are associated with improved outcome in ovarian carcinoma

Immune and inflammatory cascades may play multiple roles in ovarian cancer. We aimed to identify relationships between expression of immune and inflammatory mediators and patient outcomes. We interrogated differential gene expression of 44 markers and marker combinations (n = 1,978) in 1,656 ovarian carcinoma patient tumors, alongside matched 5-year overall survival (OS) data in silico. Using machine learning methods, we investigated whether genomic expression of these 44 mediators can discriminate between malignant and non-malignant tissues in 839 ovarian cancer and 115 non-malignant ovary samples. We furthermore assessed inflammation markers in 289 ovarian cancer patients’ sera in the Swedish Apolipoprotein MOrtality-related RISk (AMORIS) cohort. Expression of the 44 mediators could discriminate between malignant and non-malignant tissues with at least 96% accuracy. Higher expression of classical Th1, Th2, Th17, anti-parasitic/infection and M1 macrophage mediator signatures were associated with better OS. Contrastingly, inflammatory and angiogenic mediators, CXCL-12, C-reactive protein (CRP) and platelet-derived growth factor subunit A (PDGFA) were negatively associated with OS. Of the serum inflammatory markers in the AMORIS cohort, women with ovarian cancer who had elevated levels of haptoglobin (≥1.4 g/L) had a higher risk of dying from ovarian cancer compared to those with haptoglobin levels <1.4 g/L (HR = 2.09, 95% CI:1.38–3.16). Our findings indicate that elevated “classical” immune mediators, associated with response to pathogen antigen challenge, may confer immunological advantage in ovarian cancer, while inflammatory markers appear to have negative prognostic value. These highlight associations between immune protection, inflammation and clinical outcomes, and offer opportunities for patient stratification based on secretome markers.

IgE Antibodies: From Structure to Function and Clinical Translation

Immunoglobulin E (IgE) antibodies are well known for their role in mediating allergic reactions, and their powerful effector functions activated through binding to Fc receptors FcεRI and FcεRII/CD23. Structural studies of IgE-Fc alone, and when bound to these receptors, surprisingly revealed not only an acutely bent Fc conformation, but also subtle allosteric communication between the two distant receptor-binding sites. The ability of IgE-Fc to undergo more extreme conformational changes emerged from structures of complexes with anti-IgE antibodies, including omalizumab, in clinical use for allergic disease; flexibility is clearly critical for IgE function, but may also be exploited by allosteric interference to inhibit IgE activity for therapeutic benefit. In contrast, the power of IgE may be harnessed to target cancer. Efforts to improve the effector functions of therapeutic antibodies for cancer have almost exclusively focussed on IgG1 and IgG4 subclasses, but IgE offers an extremely high affinity for FcεRI receptors on immune effector cells known to infiltrate solid tumours. Furthermore, while tumour-resident inhibitory Fc receptors can modulate the effector functions of IgG antibodies, no inhibitory IgE Fc receptors are known to exist. The development of tumour antigen-specific IgE antibodies may therefore provide an improved immune functional profile and enhanced anti-cancer efficacy. We describe proof-of-concept studies of IgE immunotherapies against solid tumours, including a range of in vitro and in vivo evaluations of efficacy and mechanisms of action, as well as ex vivo and in vivo safety studies. The first anti-cancer IgE antibody, MOv18, the clinical translation of which we discuss herein, has now reached clinical testing, offering great potential to direct this novel therapeutic modality against many other tumour-specific antigens. This review highlights how our understanding of IgE structure and function underpins these exciting clinical developments.

Folate-targeted immunotherapies: Passive and active strategies for cancer

The glycoprotein FRα is a membrane-attached transport protein that is shielded from the immune system in healthy cells. However, it is upregulated in various malignancies, involved in cancer development and is also immunogenic. Furthermore, FRα is a tumor-associated antigen endowed with unique properties, thus rendering it a suitable target for immunotherapeutic development in cancer. Various anti- FRα immunotherapeutic strategies are thus currently being developed and clinically assessed for the treatment of various solid tumors. These approaches include passive anti-FRα immunotherapies, such as monoclonal antibodies, or active immunotherapies, such as CART, folate haptens and vaccines. In this review, we will explore the advances in the field of FRα-based immune therapies and discuss both their successes and shortcomings in the clinical setting.