Antitumor activity of a monoclonal antibody targeting major histocompatibility complex class I-Her2 peptide complexes

Bispecific antibody drug conjugates: Making 1+1>2

Bispecific antibody‒drug conjugates (BsADCs) represent an innovative therapeutic category amalgamating the merits of antibody‒drug conjugates (ADCs) and bispecific antibodies (BsAbs). Positioned as the next-generation ADC approach, BsADCs hold promise for ameliorating extant clinical challenges associated with ADCs, particularly pertaining to issues such as poor internalization, off-target toxicity, and drug resistance. Presently, ten BsADCs are undergoing clinical trials, and initial findings underscore the imperative for ongoing refinement. This review initially delves into specific design considerations for BsADCs, encompassing target selection, antibody formats, and the linker-payload complex. Subsequent sections delineate the extant progress and challenges encountered by BsADCs, illustrated through pertinent case studies. The amalgamation of BsAbs with ADCs offers a prospective solution to prevailing clinical limitations of ADCs. Nevertheless, the symbiotic interplay among BsAb, linker, and payload necessitates further optimizations and coordination beyond a simplistic "1 + 1" to effectively surmount the extant challenges facing the BsADC domain.

Estrogen Receptor Mutations as Novel Targets for Immunotherapy in Metastatic Estrogen Receptor-positive Breast Cancer

Estrogen receptor-positive (ER+) breast cancer is not considered immunogenic and, to date, has been proven resistant to immunotherapy. Endocrine therapy remains the cornerstone of treatment for ER+ breast cancers. However, constitutively activating mutations in the estrogen receptor alpha (ESR1) gene can emerge during treatment, rendering tumors resistant to endocrine therapy. Although these mutations represent a pathway of resistance, they also represent a potential source of neoepitopes that can be targeted by immunotherapy. In this study, we investigated ESR1 mutations as novel targets for breast cancer immunotherapy. Using machine learning algorithms, we identified ESR1-derived peptides predicted to form stable complexes with HLA-A*0201. We then validated the binding affinity and stability of the top predicted peptides through in vitro binding and dissociation assays and showed that these peptides bind HLA-A*0201 with high affinity and stability. Using tetramer assays, we confirmed the presence and expansion potential of antigen-specific CTLs from healthy female donors. Finally, using in vitro cytotoxicity assays, we showed the lysis of peptide-pulsed targets and breast cancer cells expressing common ESR1 mutations by expanded antigen-specific CTLs. Ultimately, we identified five peptides derived from the three most common ESR1 mutations (D538G, Y537S, and E380Q) and their associated wild-type peptides, which were the most immunogenic. Overall, these data confirm the immunogenicity of epitopes derived from ESR1 and highlight the potential of these peptides to be targeted by novel immunotherapy strategies.

SIGNIFICANCE

Estrogen receptor (ESR1) mutations have emerged as a key factor in endocrine therapy resistance. We identified and validated five novel, immunogenic ESR1-derived peptides that could be targeted through vaccine-based immunotherapy.

Secreted HLA-Fc fusion profiles immunopeptidome in hypoxic PDAC and cellular senescence

Human leukocyte antigens (HLA) present peptides largely from intracellular proteins on cell surfaces. As these complexes can serve as biomarkers in disease, proper identification of peptides derived from disease-associated antigens and the corresponding presenting HLA is important for the design and execution of therapeutic strategies. Yet, current mass spectrometry methods for immunopeptidomic profiling require large and complex sample inputs, hindering the study of certain disease phenotypes and lowering confidence in peptide and allele identification. Here, we describe a secreted HLA (sHLA)-Fc fusion construct for simple single HLA allele profiling in hypoxic pancreatic ductal adenocarcinoma (PDAC) and cellular senescence. This method streamlines sample preparation, enables temporal control, and provides allele-restricted target identification. Over 30,000 unique HLA-associated peptides were identified across 2 different HLA alleles and 7 cell lines, with ∼9,300 peptides newly discovered. The sHLA-Fc fusion capture technology holds the potential to expedite immunopeptidomics and advance therapeutic interest in HLA-peptide complexes.

Secreted HLA Fc-Fusion Profiles Immunopeptidome in Hypoxic PDAC and Cellular Senescence

Human leukocyte antigens (HLA) display peptides largely from intracellular proteins on the surface of cells in major histocompatibility complex (MHC)-peptide complexes. These complexes provide a biological window into the cell, and peptides derived from disease-associated antigens can serve as biomarkers and therapeutic targets. Thus, proper identification of peptides and the corresponding presenting HLA allele in disease phenotypes is important for the design and execution of therapeutic strategies using engineered T-cell receptors or antibodies. Yet, current mass spectrometry methods for profiling the immunopeptidome typically require large and complex sample inputs, complicating the study of several disease phenotypes and lowering the confidence of both peptide and allele identification. Here, we describe a novel secreted HLA (sHLA) Fc-fusion construct that allows for simple peptide identification from single HLA alleles in two important disease models: hypoxic pancreatic ductal adenocarcinoma (PDAC) and cellular senescence. We identify hypoxia and senescence-associated peptides that could act as future targets for immunotherapy. More generally, the method streamlines the time between sample preparation and injection from days to hours, yielding allele-restricted target identification in a temporally controlled manner. Overall, this method identified >30,000 unique HLA-associated peptides across two different HLA alleles and seven cell lines. Notably, ∼9,300 of these unique HLA-associated peptides had previously not been identified in the Immune Epitope Database. We believe the sHLA Fc-fusion capture technology will accelerate the study of the immunopeptidome as therapeutic interest in HLA-peptide complexes increases in cancer and beyond.

Antigen discovery for the development of cancer immunotherapy

Central to successful cancer immunotherapy is effective T cell antitumor immunity. Multiple targeted immunotherapies engineered to invigorate T cell-driven antitumor immunity rely on identifying the repertoire of T cell antigens expressed on the tumor cell surface. Mass spectrometry-based survey of such antigens ("immunopeptidomics") combined with other omics platforms and computational algorithms has been instrumental in identifying and quantifying tumor-derived T cell antigens. In this review, we discuss the types of tumor antigens that have emerged for targeted cancer immunotherapy and the immunopeptidomics methods that are central in MHC peptide identification and quantification. We provide an overview of the strength and limitations of mass spectrometry-driven approaches and how they have been integrated with other technologies to discover targetable T cell antigens for cancer immunotherapy. We highlight some of the emerging cancer immunotherapies that successfully capitalized on immunopeptidomics, their challenges, and mass spectrometry-based strategies that can support their development.

Chimeric antigen receptor T-cell therapy targeting a MAGE A4 peptide and HLA-A*02:01 complex for unresectable advanced or recurrent solid cancer: protocol for a multi-institutional phase 1 clinical trial

INTRODUCTION

Adoptive cell transfer of genetically engineered T cells is a promising treatment for malignancies; however, there are few ideal cancer antigens expressed on the cell surface, and the development of chimeric antigen receptor T cells (CAR-T cells) for solid tumour treatment has been slow. CAR-T cells, which recognise major histocompatibility complex and peptide complexes presented on the cell surface, can be used to target not only cell surface antigens but also intracellular antigens. We have developed a CAR-T-cell product that recognises the complex of HLA-A*02:01 and an epitope of the MAGE-A4 antigen equipped with a novel signalling domain of human GITR (investigational product code: MU-MA402C) based on preclinical studies.

METHODS AND ANALYSIS

This is a dose-escalation, multi-institutional, phase 1 study to evaluate the tolerability and safety of MU-MA402C for patients with MAGE A4-positive and HLA-A*02:01-positive unresectable advanced or recurrent solid cancer. Two dose cohorts are planned: cohort 1, MU-MA402C 2×10⁸/person; cohort 2, MU-MA402C 2×10⁹/person. Prior to CAR-T-cell infusion, cyclophosphamide (CPA) and fludarabine (FLU) will be administered as preconditioning chemotherapy. Three evaluable subjects per cohort, for a total of 6 subjects (maximum of 12 subjects), will be recruited for this clinical trial. The primary endpoints are safety and tolerability. The severity of each adverse event will be evaluated in accordance with Common Terminology Criteria for Adverse Events V.5.0. The secondary endpoint is efficacy. Antitumour response will be evaluated according to Response Evaluation Criteria in Solid Tumours V.1.1.

ETHICS AND DISSEMINATION

This clinical trial will be conducted in accordance with the current version of Good Clinical Practice. The protocol was approved by the Clinical Research Ethics Review Committee of Mie University Hospital (approval number F-2021-017). The trial results will be published in peer-reviewed journals and/or disseminated through international conferences.

TRIAL REGISTRATION NUMBER

jRCT2043210077.

Spatially Resolved Transcriptomes of Mammalian Kidneys Illustrate the Molecular Complexity and Interactions of Functional Nephron Segments

Available transcriptomes of the mammalian kidney provide limited information on the spatial interplay between different functional nephron structures due to the required dissociation of tissue with traditional transcriptome-based methodologies. A deeper understanding of the complexity of functional nephron structures requires a non-dissociative transcriptomics approach, such as spatial transcriptomics sequencing (ST-seq). We hypothesize that the application of ST-seq in normal mammalian kidneys will give transcriptomic insights within and across species of physiology at the functional structure level and cellular communication at the cell level. Here, we applied ST-seq in six mice and four human kidneys that were histologically absent of any overt pathology. We defined the location of specific nephron structures in the captured ST-seq datasets using three lines of evidence: pathologist's annotation, marker gene expression, and integration with public single-cell and/or single-nucleus RNA-sequencing datasets. We compared the mouse and human cortical kidney regions. In the human ST-seq datasets, we further investigated the cellular communication within glomeruli and regions of proximal tubules-peritubular capillaries by screening for co-expression of ligand-receptor gene pairs. Gene expression signatures of distinct nephron structures and microvascular regions were spatially resolved within the mouse and human ST-seq datasets. We identified 7,370 differentially expressed genes (p adj < 0.05) distinguishing species, suggesting changes in energy production and metabolism in mouse cortical regions relative to human kidneys. Hundreds of potential ligand-receptor interactions were identified within glomeruli and regions of proximal tubules-peritubular capillaries, including known and novel interactions relevant to kidney physiology. Our application of ST-seq to normal human and murine kidneys confirms current knowledge and localization of transcripts within the kidney. Furthermore, the generated ST-seq datasets provide a valuable resource for the kidney community that can be used to inform future research into this complex organ.

Engineering Antibodies Targeting p16 MHC-Peptide Complexes

Senescent cells undergo a permanent cell cycle arrest and drive a host of age-related pathologies. Recent transgenic mouse models indicate that removing cells expressing the senescence marker p16^Ink4a (p16) can increase median lifespan and delay the onset of many aging phenotypes. However, identifying and eliminating native human cells expressing p16 has remained a challenge. We hypothesize that senescent cells display peptides derived from p16 in major histocompatibility complex (MHC)-peptide complexes on the cell surface that could serve as targetable antigens for antibody-based biologics. Using Fab-phage display technology, we generated antibodies that bind to a p16 MHC-peptide complex from the human leukocyte antigen (HLA) allele HLA-B*35:01. When converted to single-chain Fab chimeric antigen receptor (CAR) constructs, these antibodies can recognize naturally presented p16 MHC-peptide complexes on the surface of cells and activate Jurkat cells. Furthermore, we developed antibodies against predicted p16 MHC-peptide complexes for HLA-A*02:01 that specifically recognize their respective antigen on the surface of cells. These tools establish a platform to survey the surface of senescent cells and provide a potential novel senolytic strategy.

Novel HLA-A2 restricted antigenic peptide derivatives with high affinity for the treatment of breast cancer expressing NY-ESO-1

Tumor immunotherapy based on specific tumor antigen has become the focus for breast cancer, and research into cancer/testes antigens (CTA) is progressing. As an important member in the CTA, NY-ESO-1 plays a crucial role in the treatment and prognosis of breast cancer. In this study, we aimed to improve the binding ability to MHC by designing and synthesizing stable NY-ESO-1-derived peptides, based on NetMHC 4.0 webserver (http://www.cbs.dtu.dk/services/NetMHC/) and HLP webserver (http://crdd.osdd.net/raghava/hlp/pep_both.htm). Moreover, after modification of the lead compound, affinity of the peptides to human leukocyte antigen-A2 (HLA-A2) was determined by a flow cytometry and an inverted fluorescence microscope in T2 cells that show high expression of HLA-A2. The results demonstrated that the affinity of peptides II-4 and II-10 to HLA-A2 was significantly better when compared to others (II-Lead, II-1 ~ II-3, II-5 ~ II-9, II-11 ~ II-15). Further studies indicated that II-4 and II-10, especially II-4, significantly promoted the maturation of HLA-A2-positive human peripheral blood-derived dendritic cells (DCs) from morphology and surface markers, the activation of CD8 + T lymphocytes, and the type-specific killing effect on HLA-A2⁺/NY-ESO-1⁺ MDA-MB-231 cells. Molecular docking studies suggested a strong interaction between peptide II-4 and HLA-A2, thereby indicating that the II-4 is a promising candidate with antigenic potential in the field of immunotherapy that needs more studies.

Synthetic tumor-specific antigenic peptides with a strong affinity to HLA-A2 elicit anti-breast cancer immune response through activating CD8+ T cells

Researches on tumor-associated antigen have become a hot target in immunotherapy, but it stagnated in the pre-clinical/clinical stages. Here, we developed a series of MAGE-A1-restricted antigenic peptides, which exhibited prominent inhibiting effect on specific breast cancer. Peptides were synthesized by Fmoc solid phase method and analyzed by online servers. The stability and affinity to HLA-A2 was assessed by inverted fluorescence and flow cytometry qualitatively and quantitatively. In vitro effect on dendritic cells (DCs) maturation was observed by morphology and surface markers. The secretion of IFN-γ in the supernatant was detected by co-incubation of DCs loaded with as-synthesized peptides and CD8⁺ T lymphocytes. The specific immune response was evaluated against 4 cell lines, and the response in MCF-7 xenografted BALB/c nude mice were further assessed. Most of the derived peptides, especially I-6, showed great HLA-A2 binding ability. Compared with cytokines, I-6 significantly induced DCs maturation and promoted CD8⁺ T lymphocytes activation. Additionally, it is more specific for the lethality of MAGE & HLA-A2 double positive cells compared with others. We successfully developed I-6 with a high affinity to HLA-A2 which could induce strong specific immune response. It could be a potential candidate for breast cancer immunotherapy, which deserves further studies.

The Antitumor Activity of TCR-Mimic Antibody-Drug Conjugates (TCRm-ADCs) Targeting the Intracellular Wilms Tumor 1 (WT1) Oncoprotein

Wilms tumor 1 (WT1) oncoprotein is an intracellular oncogenic transcription factor which is barely expressed in normal adult tissues but over expressed in a variety of leukemias and solid cancers. WT1-derived HLA-A*02:01 T cell epitope, RMFPNAPYL (RMF), is a validated target for T cell-based immunotherapy. We generated two T cell receptor mimic antibody-drug conjugates (TCRm-ADCs), ESK-MMAE, and Q2L-MMAE, against WT1 RMF/HLA-A*02:01 complex with distinct affinities, which mediate specific antitumor activity. Although ESK-MMAE showed higher tumor growth inhibition ratio in vivo, the efficacy of them was not so promising, which might be due to low expression of peptide/HLA targets. Therefore, we explored a bispecific TCRm-ADC that exerted more potent tumor cytotoxicity compared with TCRm-ADCs. Hence, our findings validate the feasibility of the presenting intracellular peptides as the targets of ADCs, which broadens the antigen selection range of antibody-based drugs and provides new strategies for precision medicine in tumor therapy.

Targeting the MHC Ligandome by Use of TCR-Like Antibodies

Monoclonal antibodies (mAbs) are valuable as research reagents, in diagnosis and in therapy. Their high specificity, the ease in production, favorable biophysical properties and the opportunity to engineer different properties make mAbs a versatile class of biologics. mAbs targeting peptide–major histocompatibility molecule (pMHC) complexes are often referred to as “TCR-like” mAbs, as pMHC complexes are generally recognized by T-cell receptors (TCRs). Presentation of self- and non-self-derived peptide fragments on MHC molecules and subsequent activation of T cells dictate immune responses in health and disease. This includes responses to infectious agents or cancer but also aberrant responses against harmless self-peptides in autoimmune diseases. The ability of TCR-like mAbs to target specific peptides presented on MHC allows for their use to study peptide presentation or for diagnosis and therapy. This extends the scope of conventional mAbs, which are generally limited to cell-surface or soluble antigens. Herein, we review the strategies used to generate TCR-like mAbs and provide a structural comparison with the analogous TCR in pMHC binding. We further discuss their applications as research tools and therapeutic reagents in preclinical models as well as challenges and limitations associated with their use.

TCR-like antibody drug conjugates mediate killing of tumor cells with low peptide/HLA targets

The currently marketed antibody-drug conjugates (ADC) destabilize microtubule assembly in cancer cells and initiate apoptosis in patients. However, few tumor antigens (TA) are expressed at high densities on cancer lesions, potentially minimizing the therapeutic index of current ADC regimens. The peptide/human leukocyte antigen (HLA) complex can be specifically targeted by therapeutic antibodies (designated T cell receptor [TCR]-like antibodies) and adequately distinguish malignant cells, but has not been the focus of ADC development. We analyzed the killing potential of TCR-like ADCs when cross-linked to the DNA alkylating compound duocarmycin. Our data comprise proof-of-principle results that TCR-like ADCs mediate potent tumor cytotoxicity, particularly under common scenarios of low TA/HLA density, and support their continued development alongside agents that disrupt DNA replication. Additionally, TCR-like antibody ligand binding appears to play an important role in ADC functionality and should be addressed during therapy development to avoid binding patterns that negate ADC killing efficacy.

TCR-like antibodies mediate complement and antibody-dependent cellular cytotoxicity against Epstein-Barr virus-transformed B lymphoblastoid cells expressing different HLA-A*02 microvariants

Epstein-Barr virus (EBV) is a common gammaherpesvirus associated with various human malignancies. Antibodies with T cell receptor-like specificities (TCR-like mAbs) provide a means to target intracellular tumor- or virus-associated antigens by recognising their processed peptides presented on major histocompatibility complex (MHC) class I (pMHC) complexes. These antibodies are however thought to be relevant only for a single HLA allele. Here, we show that HLA-A*02:01-restricted EBV antigenic peptides EBNA1_562-570, LMP1_125-133 and LMP2A_426-434 display binding degeneracy towards HLA-A*02 allelic microvariants, and that these pMHC complexes are recognised by anti-EBV TCR-like mAbs E1, L1 and L2 raised in the context of HLA-A*02:01. These antibodies bound endogenously derived pMHC targets on EBV–transformed human B lymphoblastoid cell lines expressing A*02:01, A*02:03, A*02:06 and A*02:07 alleles. More importantly, these TCR-like mAbs mediated both complement-dependent and antibody-dependent cellular cytotoxicity of these cell lines in vitro. This finding suggests the utility of TCR-like mAbs against target cells of closely related HLA subtypes, and the potential applicability of similar reagents within populations of diverse HLA-A*02 alleles.

Targeting Epstein-Barr virus-transformed B lymphoblastoid cells using antibodies with T-cell receptor-like specificities

Epstein-Barr virus (EBV) is an oncovirus associated with several human malignancies including posttransplant lymphoproliferative disease in immunosuppressed patients. We show here that anti-EBV T-cell receptor-like monoclonal antibodies (TCR-like mAbs) E1, L1, and L2 bound to their respective HLA-A*0201-restricted EBV peptides EBNA1562-570, LMP1125-133, and LMP2A426-434 with high affinities and specificities. These mAbs recognized endogenously presented targets on EBV B lymphoblastoid cell lines (BLCLs), but not peripheral blood mononuclear cells, from which they were derived. Furthermore, these mAbs displayed similar binding activities on several BLCLs, despite inherent heterogeneity between different donor samples. A single weekly administration of the naked mAbs reduced splenomegaly, liver tumor spots, and tumor burden in BLCL-engrafted immunodeficient NOD-SCID/Il2rg(-/-) mice. In particular, mice that were treated with the E1 mAb displayed a delayed weight loss and significantly prolonged survival. In vitro, these TCR-like mAbs induced early apoptosis of BLCLs, thereby enhancing their Fc-dependent phagocytic uptake by macrophages. These data provide evidence for TCR-like mAbs as potential therapeutic modalities to target EBV-associated diseases.

Activity of 8F4, a T-cell receptor-like anti-PR1/HLA-A2 antibody, against primary human AML in vivo

The PR1 peptide, derived from the leukemia-associated antigens proteinase 3 and neutrophil elastase, is overexpressed on HLA-A2 in acute myeloid leukemia (AML). We developed a high affinity T cell receptor-like murine monoclonal antibody, 8F4, which binds to the PR1/HLA-A2 complex, mediates lysis of AML, and inhibits leukemia colony formation. Here, we explored whether 8F4 was active in vivo against chemotherapy-resistant AML, including secondary AML. In a screening model, co-incubation of AML with 8F4 ex vivo prevented engraftment of all tested AML subtypes in immunodeficient NSG mice. In a treatment model of established human AML, administration of 8F4 significantly reduced or eliminated AML xenografts and extended survival compared with isotype antibody-treated mice. Moreover, in secondary transfer experiments, mice inoculated with bone marrow from 8F4-treated mice showed no evidence of AML engraftment, supporting possible activity of 8F4 against the subset of AML with self-renewing potential. Our data provide evidence that 8F4 antibody is highly active in AML, including chemotherapy-resistant disease, supporting its potential use as a therapeutic agent in patients with AML.

Sinuleptolide inhibits proliferation of oral cancer Ca9-22 cells involving apoptosis, oxidative stress, and DNA damage

OBJECTIVE

Sinuleptolide, a soft corals-derived bioactive norditerpenoid, is a marine natural product with a potent anti-inflammatory effect. We evaluate the potential anti-oral cancer effects of sinuleptolide and investigate the possible mechanisms involved.

DESIGNS

Cell viability, cell cycle, apoptosis, reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and DNA damage analyses were performed.

RESULTS

In a cell viability assay, we found that sinuleptolide is dose-responsively antiproliferative against oral gingival cancer Ca9-22 cells but less harmful to normal human gingival fibroblast (HGF-1) cells (P<0.001). In cell cycle analysis, sinuleptolide induced subG1 accumulation at a higher dose and led to G2/M arrest of Ca9-22 cells (P<0.005). Apoptosis was significantly increased in sinuleptolide-treated Ca9-22 cells based on annexin V and poly(ADP-ribose) polymerase (PARP) expressions (P<0.05-0.0001). Based on flow cytometer analysis, sinuleptolide also induced the generation of ROS and decreased MMP in a dose-responsive manner (P<0.05-0.0001). DNA damage increased dose-responsively after sinuleptolide treatments (P < 0.001) based on comet and γH2AX assays.

CONCLUSION

Sinuleptolide can induce an antiproliferation of oral cancer Ca9-22 cells involving apoptosis, oxidative stress and DNA damage, suggesting that sinuleptolide represents a potential chemotherapeutic drug for oral cancer treatment.

Human Leukocyte Antigen-Presented Macrophage Migration Inhibitory Factor Is a Surface Biomarker and Potential Therapeutic Target for Ovarian Cancer

T cells recognize cancer cells via HLA/peptide complexes, and when disease overtakes these immune mechanisms, immunotherapy can exogenously target these same HLA/peptide surface markers. We previously identified an HLA-A2-presented peptide derived from macrophage migration inhibitory factor (MIF) and generated antibody RL21A against this HLA-A2/MIF complex. The objective of the current study was to assess the potential for targeting the HLA-A2/MIF complex in ovarian cancer. First, MIF peptide FLSELTQQL was eluted from the HLA-A2 of the human cancerous ovarian cell lines SKOV3, A2780, OV90, and FHIOSE118hi and detected by mass spectrometry. By flow cytometry, RL21A was shown to specifically stain these four cell lines in the context of HLA-A2. Next, partially matched HLA-A*02:01+ ovarian cancer (n = 27) and normal fallopian tube (n = 24) tissues were stained with RL21A by immunohistochemistry to assess differential HLA-A2/MIF complex expression. Ovarian tumor tissues revealed significantly increased RL21A staining compared with normal fallopian tube epithelium (P < 0.0001), with minimal staining of normal stroma and blood vessels (P < 0.0001 and P < 0.001 compared with tumor cells) suggesting a therapeutic window. We then demonstrated the anticancer activity of toxin-bound RL21A via the dose-dependent killing of ovarian cancer cells. In summary, MIF-derived peptide FLSELTQQL is HLA-A2-presented and recognized by RL21A on ovarian cancer cell lines and patient tumor tissues, and targeting of this HLA-A2/MIF complex with toxin-bound RL21A can induce ovarian cancer cell death. These results suggest that the HLA-A2/MIF complex should be further explored as a cell-surface target for ovarian cancer immunotherapy.

T cell receptor mimic antibodies for cancer therapy

The major hurdle to the creation of cancer-specific monoclonal antibodies (mAb) exhibiting limited cross-reactivity with healthy human cells is the paucity of known tumor-specific or mutated protein epitopes expressed on the cancer cell surface. Mutated and overexpressed oncoproteins are typically cytoplasmic or nuclear. Cells can present peptides from these distinguishing proteins on their cell surface in the context of human leukocyte antigen (HLA). T cell receptor mimic (TCRm) mAb can be discovered that react specifically to these complexes, allowing for selective targeting of cancer cells. The state-of-the-art for TCRm and the challenges and opportunities are discussed. Several such TCRm are moving toward clinical trials now.

Emerging immunotherapy strategies in breast cancer

Although immunogenicity is typically associated with renal cell carcinomas and melanoma, there are several compelling reasons why immune-based therapies should be explored in breast cancer. First, breast cancers express multiple putative tumor-associated antigens, such as HER-2 and MUC-1, which have been the successful focus of vaccine development over the past decade, translating into tumor-specific immune responses and, in some cases, clinical benefit. Second, passive immune strategies with anti-HER-2 antibodies, such as trastuzumab and pertuzumab, have led to survival benefits in breast cancer. Finally, the successes observed with novel immunotherapeutic strategies, such as immune checkpoint blockade and adoptive T-cell therapies in other malignancies, combined with a growing body of literature that supports an interplay between solid tumors and the immune system, indicate that these strategies have the potential to revolutionize the treatment of breast cancer.

Defining the expression hierarchy of latent T-cell epitopes in Epstein-Barr virus infection with TCR-like antibodies

Epstein-Barr virus (EBV) is a gamma herpesvirus that causes a life-long latent infection in human hosts. The latent gene products LMP1, LMP2A and EBNA1 are expressed by EBV-associated tumors and peptide epitopes derived from these can be targeted by CD8 Cytotoxic T-Lymphocyte (CTL) lines. Whilst CTL-based methodologies can be utilized to infer the presence of specific latent epitopes, they do not allow a direct visualization or quantitation of these epitopes. Here, we describe the characterization of three TCR-like monoclonal antibodies (mAbs) targeting the latent epitopes LMP1(125-133), LMP2A(426-434) or EBNA1(562-570) in association with HLA-A0201. These are employed to map the expression hierarchy of endogenously generated EBV epitopes. The dominance of EBNA1(562-570) in association with HLA-A0201 was consistently observed in cell lines and EBV-associated tumor biopsies. These data highlight the discordance between MHC-epitope density and frequencies of associated CTL with implications for cell-based immunotherapies and/or vaccines for EBV-associated disease.