Tumor-specific Monoclonal Antibodies Research Articles

Exosomes: The Role in Tumor Tolerance and the Potential Strategy for Tumor Therapy

Drug and radiotherapy resistance is the primary cause of treatment failure and poor prognosis in patients with tumors. Exosomes are extracellular vesicles loaded with substances such as nucleic acids, lipids, and proteins that transmit information between cells. Studies have found that exosomes are involved in tumor therapy resistance through drug efflux, promotion of drug resistance phenotypes, delivery of drug-resistance-related molecules, and regulation of anti-tumor immune responses. Based on their low immunogenicity and high biocompatibility, exosomes have been shown to reduce tumor therapy resistance by loading nucleic acids, proteins, and drugs inside xosomes or expressing tumor-specific antigens, target peptides, and monoclonal antibodies on their phospholipid bimolecular membranes. Consequently, future research on genetically engineered exosomes is expected to eliminate resistance to tumor treatment, improving the overall prognosis of patients with tumors.

Neutrophils and their friends.

Neutrophils and their friends.

Targeted Cytokine Delivery for Cancer Treatment: Engineering and Biological Effects

Anti-tumor properties of several cytokines have already been investigated in multiple experiments and clinical trials. However, those studies evidenced substantial toxicities, even at low cytokine doses, and the lack of tumor specificity. These factors significantly limit clinical applications. Due to their high specificity and affinity, tumor-specific monoclonal antibodies or their antigen-binding fragments are capable of delivering fused cytokines to tumors and, therefore, of decreasing the number and severity of side effects, as well as of enhancing the therapeutic index. The present review surveys the actual antibody-cytokine fusion protein (immunocytokine) formats, their targets, mechanisms of action, and anti-tumor and other biological effects. Special attention is paid to the formats designed to prevent the off-target cytokine-receptor interactions, potentially inducing side effects. Here, we describe preclinical and clinical data and the efficacy of the antibody-mediated cytokine delivery approach, either as a single therapy or in combination with other agents.

BCL11B depletion induces the development of highly cytotoxic innate T cells out of IL-15 stimulated peripheral blood αβ CD8+ T cells

ABSTRACT BCL11B, an essential transcription factor for thymopoiesis, regulates also vital processes in post-thymic lymphocytes. Increased expression of BCL11B was recently correlated with the maturation of NK cells, whereas reduced BCL11B levels were observed in native and induced T cell subsets displaying NK cell features. We show that BCL11B-depleted CD8+ T cells stimulated with IL-15 acquired remarkable innate characteristics. These induced innate CD8+ (iiT8) cells expressed multiple innate receptors like NKp30, CD161, and CD16 as well as factors regulating migration and tissue homing while maintaining their T cell phenotype. The iiT8 cells effectively killed leukemic cells spontaneously and neuroblastoma spheroids in the presence of a tumor-specific monoclonal antibody mediated by CD16 receptor activation. These iiT8 cells integrate the innate natural killer cell activity with adaptive T cell longevity, promising an interesting therapeutic potential. Our study demonstrates that innate T cells, albeit of limited clinical applicability given their low frequency, can be efficiently generated from peripheral blood and applied for adoptive transfer, CAR therapy, or combined with therapeutic antibodies.

Immunotherapy for cancer treatment.

Immunotherapy is an effective way to treat many diseases associated with disorders of the immune system by modulating immune response. It involves several ways of manipulating the immune system, which either suppress the immune response or, on the contrary, stimulates it. Immunotherapy is currently of immense importance not only in the context of the treatment of autoimmune diseases and immunodeficiencies, but it is also a promising method for treating cancer. Efforts to use the bodys own anti-tumor response have led to the discovery of alternative treatments for cancer. The aim of this paper is to provide a literature review focused on the current possibilities of cancer immunotherapy. In addition to classical procedures such as chemotherapy and radiotherapy, treatments consisting of adoptive cell therapy and blockade of immune checkpoints are being increasingly indicated. The latest form of adoptive cell therapy is the use of T-lymphocytes expressing chimeric antigen receptors. This type of treatment is indicated for hematological cancers. In recent years, a new approach to the treatment of cancer has emerged using blockade of immune checkpoints by monoclonal antibodies. At present, antitumor therapy focuses on blocking of inhibitory molecules - cytotoxic T-lymfocyte antigen 4 (CTLA-4) and programmed cell death 1 (PD-1). Administration of anti-CTLA-4 receptor specific monoclonal antibodies blocks binding between CTLA-4 receptors and B7 ligands, thereby preventing inhibition of activated cytotoxic T cells. Another type of checkpoints of the immune response include PD-1 molecules expressed on the surface of T-lymphocytes, B-lymphocytes, but also on the surface of myeloid cells. Blockade of PD-1 receptors and PD-L1 ligands prevents the inhibition of T-lymphocytes by tumor cells, leading to an increase in the immune systems ability to recognize tumor cells and subsequently destroy them. Blockade of PD-1 receptors and PD-L1 ligands prevents the inhibition of T-lymphocytes by tumor cells, leading to an increased immune response to the recognition of tumor cells and their subsequent destruction. An alternative form of tumor treatment is the administration of tumor vaccines and tumor-specific monoclonal antibodies (mAbs). The use of mAbs to kill tumors requires the expression of tumor-specific antigens on the surface of tumor cells. Through these receptors, mAb targets cytotoxic cells, toxins, drugs, or radioisotopes to tumor cells and thereby destroys them. Also, mAbs are able to block angiogenesis, which is crucial in tumor cell proliferation.

Novel antigens for targeted radioimmunotherapy in hepatocellular carcinoma.

Liver cancer is the sixth common cancer and forth cause of cancer-related death worldwide. Based on usually advanced stages of hepatocellular carcinoma (HCC) at the time of diagnosis, therapeutic options are limited and, in many cases, not effective, and typically result in the tumor recurrence with a poor prognosis. Radioimmunotherapy (RIT) offers a selective internal radiation therapy approach using beta or alpha emitting radionuclides conjugated with tumor-specific monoclonal antibodies (mAbs), or specific selective peptides. When compared to chemotherapy or radiotherapy, radiolabeled mAbs against cancer-associated antigens could provide a high therapeutic and exclusive radiation dose for cancerous cells while decreasing the exposure-induced side effects to healthy tissues. The recent advances in cancer immunotherapy, such as blockade of immune-checkpoint inhibitors (ICIs), has changed the landscape of cancer therapy, and the efficacy of different classes of immunotherapy has been tested in many clinical trials. Taking into account the use of ICIs in the liver tumor microenvironment, combined therapies with different approaches may enhance the outcome in the future clinical studies. With the development of novel immunotherapy treatment options in the recent years, there has been a great deal of information about combining the diverse treatment modalities to boost the effectiveness of immunomodulatory drugs. In this opinion review, we will discuss the recent advancements in RIT. The current status of immunotherapy and internal radiotherapy will be updated, and we will propose novel approaches for the combination of both techniques. Potential target antigens for radioimmunotherapy in Hepatocellular carcinoma (HCC). HCC radioimmunotherapy target antigens are the most specific and commonly accessible antigens on the surface of HCC cells. CTLA-4 ligand and receptor, TAMs, PD-1/PD-L, TIM-3, specific IEXs/TEXs, ROBO1, and cluster of differentiation antigens CD105, CD147 could all be used in HCC radioimmunotherapy. Abbreviations: TAMs, tumor-associated macrophages; CTLA-4, cytotoxic T-lymphocyte associated antigen-4; PD-1, Programmed cell death protein 1; PD-L, programmed death-ligand1; TIM-3, T-cell immunoglobulin (Ig) and mucin-domain containing protein-3; IEXs, immune cell-derived exosomes; TEXs, tumor-derived exosomes.

Immunotherapy in neoplastic diseases

Malignant tumors occur when neoplastic cells escape the supervision of the immune system. For this reason, in recent years, the interest has been focused on immunotherapy, the goal of which is to strengthen and focus the immune response against the tumor, exploiting the unique properties of the immune system, namely memory, potency and specificity that no drug possesses. Major developments in the field of immunology have already provided the knowledge and techniques needed to develop new immunotherapeutic approaches, in particular active, passive and adoptive immunotherapy. Although induction of the anti-tumor response by vaccination (active immunotherapy) appears to be theoretically logical and is expected to be successful, the administration of tumor-specific monoclonal antibodies has demonstrated, through evidence from clinical trials, a therapeutic response in patients receiving this treatment. Recently, a new approach has been developed, called chimeric antigen receptor therapy (CAR chimeric antigen receptor). The gates for the transition to the era of immunotherapy have been opened, as recent clinical successes signal the beginning of the evolution of immunotherapy from the experimental phase to established therapy.

Anti-EpCAM functionalized graphene oxide vector for tumor targeted siRNA delivery and cancer therapy

Graphene oxide (GO) has emerged as a potential drug delivery vector. For siRNA delivery, GO should be modified to endow it with gene delivery ability and targeting effect. However, the cationic materials used previously usually had greater toxicity. In this study, GO was modified with a non-toxicity cationic material (chitosan) and a tumor specific monoclonal antibody (anti-EpCAM) for the delivery of survivin-siRNA (GCE/siRNA). And the vector (GCE) prepared was proved with excellent biosafety and tumor targeting effect. The GCE exhibited superior performance in loading siRNA, maintained stability in different solutions and showed excellent protection effect for survivin-siRNA in vitro. The gene silencing results in vitro showed that the mRNA level and protein level were down-regulated by 48.24% ± 2.50% and 44.12% ± 3.03%, respectively, which was equal with positive control (P > 0.05). It was also demonstrated that GCE/siRNA had a strong antitumor effect in vitro, which was attributed to the efficient antiproliferation, and migration and invasion inhibition effect of GCE/siRNA. The results in vivo indicated that GCE could accumulate siRNA in tumor tissues. The tumor inhibition rate of GCE/siRNA 54.74% ± 5.51% was significantly higher than control 4.87% ± 8.49%. Moreover, GCE/siRNA showed no toxicity for blood and main organs, suggesting that it is a biosafety carrier for gene delivery. Taken together, this study provides a novel design strategy for gene delivery system and siRNA formulation.

Defucosylation of Tumor-Specific Humanized Anti-MUC1 Monoclonal Antibody Enhances NK Cell-Mediated Anti-Tumor Cell Cytotoxicity.

Simple SummaryAntibodies with their high specificity to antigens have been widely used in cancer immunotherapy. Natural killer (NK) cells are a group of innate immune cells which have strong cytotoxicity against cancerous cells, virus infected cells, or transformed cells. NK cells express abundant Fc receptors that can bind tumor-specific antibodies, thus allowing them to precisely redirect and eliminate cancer cells. In this study, we demonstrated that NK cells cytotoxicity toward MUC1-positive hematologic and solid tumor can be further enhanced by a humanized 5E5 anti-MUC1 antibody. Furthermore, Fc defucosylation of the antibodies further boosted the kill capacity of NK cells. We believe that our humanized anti-MUC1 antibody is a promising therapeutic candidate for clinical cancer treatment.Antibodies are commonly used in cancer immunotherapy because of their high specificity for tumor-associated antigens. The binding of antibodies can have direct effects on tumor cells but also engages natural killer (NK) cells via their Fc receptor. Mucin 1 (MUC1) is a highly glycosylated protein expressed in normal epithelial cells, while the under-glycosylated MUC1 epitope (MUC1-Tn/STn) is only expressed on malignant cells, making it an interesting diagnostic and therapeutic target. Several anti-MUC1 antibodies have been tested for therapeutic applications in solid tumors thus far without clinical success. Herein, we describe the generation of fully humanized antibodies based on the murine 5E5 antibody, targeting the tumor-specific MUC1-Tn/STn epitope. We confirmed that these antibodies specifically recognize tumor-associated MUC1 epitopes and can activate human NK cells in vitro. Defucosylation of these newly developed anti-MUC1 antibodies further enhanced antigen-dependent cellular cytotoxicity (ADCC) mediated by NK cells. We show that endocytosis inhibitors augment the availability of MUC1-Tn/STn epitopes on tumor cells but do not further enhance ADCC in NK cells. Collectively, this study describes novel fully humanized anti-MUC1 antibodies that, especially after defucosylation, are promising therapeutic candidates for cellular immunotherapy.

Biomarkers and Target Therapy for Lung Cancer

Precision (target) medicine is proposed as a new strategy to identify and develop new highly selective drugs against specific targets for the disease and more precise tailoring of medicines to the target populations of patients. Precision medicine can be an important approach to create more novel and safer therapeutics (tyrosine kinase inhibitors, tumour specific monoclonal antibodies) for patients with gene mutation, aberrations, or protein over-expression. Precision medicine requires an understanding mutational processes, and heterogeneity between cancer cells during tumor evolution. The present review briefly define various heterogeneities and potential associations with drug efficacy and resistance, emphasize the importance to develop functional biomarkers to monitor drug efficacy and resistance, and define opportunities and challenges of precision medicine for clinical practice.

Abstract P3-10-19: Precise targeting of POLR2A for treating triple negative breast cancer with Chr17p loss

Abstract Triple-negative breast cancer (TNBC) is a molecularly diverse and clinically heterogeneous disease. The challenges for developing novel treatment approaches for TNBC are the paucity of actionable targets, lack of targeted therapies, and poor prognosis of patients. Breast cancer genomics revealed that heterozygous deletion of chromosome 17p (Chr17p) is the most prevalent (53%) event in TNBC. Within the 17p deletion region is the tumor suppressor TP53 (encoding p53), whose deletion or mutation has been long known as a primary tumorigenic driver. However, it remains unclear whether the deletion event, which often includes as many as 200 genes, impacts tumorigenesis beyond TP53 loss alone. While p53 aberrancy promotes proliferation, metabolism and metastatic potential of the TNBC cells, we found that heterozygous deletion of Chr17p is tightly correlated with poor cytotoxicity of tumor infiltrating lymphocytes (TILs) and poor clinical outcomes in patients with TNBC. This result suggests that selective advantage due to Chr17p loss reflects the combined impact of TP53 loss and the reduced dosage of co-deleted genes. Our recent study also identified POLR2A in the TP53-neighboring region as a collateral vulnerability target in the TNBC tumors with Chr17p loss, suggesting that inhibition of POLR2A may be a precision therapy approach for TNBC. As a proof-of-concept, we designed pH-activated nanoparticles (termed as nanobomb) for delivery of POLR2A siRNA, which enhances bioavailability and improves endo/lysosomal escape of the siRNA. In this study (Nature Nanotechnology, 2019)1, we demonstrated that suppressing POLR2A expression with the siRNA-laden nanoparticles led to marked growth reduction of TNBC tumors with 17p loss. Despite recent success of the first FDA-approved RNAi-based therapy for polyneuropathy, the issues of RNAi-based drugs, such as non-specific and incomplete knockdown, can make RNAi unpredictable, slow, and risky, in particular in drug discovery, where speed and reliability of results are crucial factors. To accelerate the translational development of our important finding, we will use α-amanitin, a natural small compound isolated from Amanita phalloides, to specifically inhibit POLR2A (Kd ∼10−9 M). However, free form of α-amanitin causes liver toxicity via the interaction with the hepatocyte-specific OATP1B3 transporter, limiting its clinical applications. To overcome the drug toxicity of α-amanitin, we have been developing α-amanitin-based antibody-drug conjugates (ADC). This approach inhibits the specific uptake of α-amanitin into hepatocytes and increases tumor-specific targeting using tumor-specific monoclonal antibodies. This type of ADC showed significant efficacy in inhibiting the growth of colorectal tumors with heterozygous deletion of TP53 and POLR2A (Nature, 2015)2. Here, we propose that heterozygous deletion of Chr17p not only contributes to TNBC tumorigenesis, but also confers therapeutic vulnerabilities, which can be utilized to develop novel targeted cancer therapy. Refernces 1. Xu,J. et al. Precise targeting of POLR2A as a therapeutic strategy for human triple negative breast cancer. Nat. Nanotechnol. 14, 388-397 (2019). 2. Liu,Y. et al. TP53 loss creates therapeutic vulnerability in colorectal cancer. Nature 520, 697-701 (2015). Citation Format: Xiongbin Lu, Yujing Li, Yifan Sun, Kevin Van der Jeught, Michael Kulke, Pahl Andreas, Xinna Zhang, Xiaoming He, Chi Zhang. Precise targeting of POLR2A for treating triple negative breast cancer with Chr17p loss [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-10-19.

Abstract 3733: Development of photoimmunotherapy for colon cancer in nude mice models

Abstract Introduction: Photoimmunotherapy (PIT) uses tumor specific monoclonal antibodies conjugated to photosensitizer phthalocyanine dye IR700 to produce cytotoxicity. To date, there is no published data on the use of PIT in colorectal cancers, which could be useful as an adjunct to surgery to prevent local recurrence, or as a primary therapy. Methods: Humanized anti-CEA antibody (m5A) was conjugated to IR700CW dye (LI-COR). In vitro PIT was performed using a human colon cancer cell line LS174T. Cancer cells (2x103) were seeded on a 96-well plate and incubated for 24 hours. m5A-IR700CW containing media was added to the cells. Cells received either 2 minutes of PIT or no treatment. PIT was administered at 4 J/cm2, 8 J/cm2 or 16 J/cm2. Cell viability was measured on a microplate reader with CellTiter 96 Aqueous One Solution (Promega, Madison, WI). Subcutaneous implantation of LS174T was performed on the bilateral flanks of four male nude mice. Tail vein injection of 25 micrograms of m5A-IR700CW reconstituted in 100 microliters PBS was performed for each mouse. Animal imaging was performed with a LI-COR Pearl Trilogy imaging system. Right flank tumors of three mice were treated with a 690 nm laser at 150 mW/cm2 for 30 minutes, delivering a total of 270 J/cm2. A non-treated mouse served as the control. Images were obtained prior to PIT, immediately after PIT and 10 minutes, 20 minutes, 30 minutes and 24 hours after treatment. Maximum fluorescence intensity was measured at each time point. Tumor size was measured prior to treatment, 24 hours, 48 hours, 5 days and 10 days after treatment. Results: In vitro PIT was effective to kill the cancer cells in a dose response manner. In vivo PIT decreased tumor fluorescence intensity in a time-dependent manner. PIT arrested tumor growth in all mice, compared to the control, which demonstrated continuous tumor growth. Conclusion: PIT affects cancer cell death in vitro and arrests tumor growth in colon cancer models. Citation Format: Hannah Hollandsworth, Siamak Amirfakhri, Filemoni Filemoni, Sahar Razemjooie, Paul Yazaki, Robert Hoffman, Michael Bouvet. Development of photoimmunotherapy for colon cancer in nude mice models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3733.

Improved Protein Toxin Delivery Based on ATTEMPTS Systems.

Ribosome-inactivating proteins (RIPs) are wildly found in multiple species of plants, bacteria and fungi. As a special family of protein toxins, RIPs can inhibit protein synthesis and induce cell death via inactivating ribosome in eukaryotic cells. Thus, RIPs have been applied for anti-tumor therapy in the past two decades. However, because of poor cell permeability, nonselective mode of action for tumor cells, poor pharmacokinetic profiles and immunogenicity, their clinical application has been severely constrained. As an effort to overcome these obstacles, tumor-specific monoclonal antibodies (mAb) have been conjugated to RIPs (forming so called "immunotoxins") specifically to increase their cytotoxicity and provide tumor targeting. Nevertheless, immunotoxins yet have not fully resolved all the issues and critical challenges still remain, such as immunogenicity and inability to penetrate into the deep site of tumor. To overcome the constrain of immunotoxins, the novel cell-penetrating peptide (CPP)- modified ATTEMPTS systems based on combination of CPP-mediated penetration and antibodymediated tumor targeting, with triggerable drug release function, were developed to achieve effective and safe delivery of protein toxin. The CPP-modified ATTEMPTS systems showed effective protamine-triggered CPP-toxin release and thus enhanced CPP-mediated cellular uptake and cytotoxicity. It also showed antibodymediated in vivo tumor targeting and significantly increased in vivo tumor growth suppression with limited systematic toxicity. The CPP-modified ATTEMPTS systems were developed and demonstrated as a proof-ofconcept for CPP-based protein toxin delivery with triggerable antibody targeting to improve the druggability of protein toxin drugs. The systems showed the potential application of protein toxin clinical translation in anticancer treatment.

Checkpoint inhibition in pediatric hematologic malignancies

ABSTRACTImmune surveillance comprising of adaptive and innate immune systems is naturally designed to eliminate cancer development; overexpression of inhibitory receptors and their ligands prevent this check and lead to evasion and hence cancer progression and metastasis. The use of tumor-specific monoclonal antibodies (MAbs) targeting these checkpoint regulators is promising and has led to this novel field of cancer immunotherapy. The first antibody directed against cytotoxic T-lymphocyte associated protein 4 (CTLA-4), ipilimumab, showed promising results in clinical trials and was approved by the US Food and Drug Administration (FDA) for the treatment of metastatic melanoma in 2011. Since then, various other immune checkpoint inhibitors are being studied in preclinical and clinical trial phases, targeting programmed-death-1 (PD-1) and its ligand programmed death ligand 1 (PD-L1), T cell lymphocyte activation gene-3 (LAG-3), and others. Results from clinical trials are promising, and currently this approach has proven effective and safe in patients with solid tumors and some hematological malignancies in adults. In general, CTLA-4 and PD-1 inhibitors are well tolerated; however, the augmented immune response enabled by this class of agents is associated with a unique group of side effects called immune-related adverse events (irAEs). Experience in pediatrics using immune checkpoint inhibitors for hematological malignancies is limited to Hodgkin's disease and non-Hodgkin's lymphoma as in the ongoing Children's Oncology Group (COG) protocol ADVL1412. Therapeutic advances in childhood leukemia and lymphoma (TACL) consortium will initiate an early phase clinical trial with PD-1 inhibitor nivolumab in relapsed/refractory acute myeloid leukemia (AML) in the next few months.

Monoclonal Antibodies Radiolabeling with Rhenium-188 for Radioimmunotherapy.

Rhenium-188, obtained from an alumina-based tungsten-188/rhenium-188 generator, is actually considered a useful candidate for labeling biomolecules such as antibodies, antibody fragments, peptides, and DNAs for radiotherapy. There is a widespread interest in the availability of labeling procedures that allow obtaining 188Re-labeled radiopharmaceuticals for various therapeutic applications, in particular for the rhenium attachment to tumor-specific monoclonal antibodies (Mo)Abs for immunotherapy. Different approaches have been developed in order to obtain 188Re-radioimmunoconjugates in high radiochemical purity starting from the generator eluted [188Re]ReO4−. The aim of this paper is to provide a short overview on 188Re-labeled (Mo)Abs, focusing in particular on the radiolabeling methods, quality control of radioimmunoconjugates, and their in vitro stability for radioimmunotherapy (RIT), with particular reference to the most important contributions published in literature in this topic.

High-efficiency lysis of cervical cancer by allogeneic NK cells derived from umbilical cord progenitors is independent of HLA status

Down-regulation of HLA in tumor cells, low numbers and dysfunctionality of NK cells are commonly observed in patients with end-stage cervical cancer. Adoptive transfer of high numbers of cytotoxic NK cells might be a promising treatment approach in this setting. Here, we explored the cytotoxic efficacy on ten cervical cancer cell lines of activated allogeneic NK cells from two sources, i.e., peripheral blood (PBNK) with and without cetuximab (CET), a tumor-specific monoclonal antibody directed against EGFR, or derived from umbilical cord blood (UCB-NK). Whereas CET monotherapy was ineffective against the panel of cervical cancer cell lines, irrespective of their EGFR expression levels and despite their RASwt status, it significantly enhanced the in vitro cytotoxic efficacy of activated PBNK (P = 0.002). Equally superior cytotoxicity over activated PBNK alone was achieved by UCB-NK (P < 0.001). Both PBNK- and UCB-NK-mediated cytotoxic activity was dependent on the NK-activating receptors natural killer group 2, member D receptor (NKG2D) and DNAX accessory molecule-1 (DNAM-1) (P < 0.05) and unrelated to expression levels of the inhibitory receptors HLA-E and/or HLA-G. Most strikingly, whereas the PBNK’s cytotoxic activity was inversely correlated with HLA-ABC levels (P = 0.036), PBNK + CET and UCB-NK cytotoxicity were entirely independent of HLA-ABC expression. In conclusion, this study provides a rationale to initiate a clinical trial for cervical cancer with adoptively transferred allogeneic NK cells, employing either UCB-NK or PBNK + CET for EGFR-expressing tumors. Adoptive transfer of UCB-NK might serve as a generally applicable treatment for cervical cancer, enabled by HLA-, histology- and HPV-independent killing mechanisms.

Anti-GD2 mAbs and next-generation mAb-based agents for cancer therapy.

Tumor-specific monoclonal antibodies (mAbs) have demonstrated efficacy in the clinic, becoming an important approach for cancer immunotherapy. Due to its limited expression on normal tissue, the GD2 disialogangloside expressed on neuroblastoma cells is an excellent candidate for mAb therapy. In 2015, dinutuximab (an anti-GD2 mAb) was approved by the US FDA and is currently used in a combination immunotherapeutic regimen for the treatment of children with high-risk neuroblastoma. Here, we review the extensive preclinical and clinical development of anti-GD2 mAbs and the different mechanisms by which they mediate tumor cell killing. In addition, we discuss different mAb-based strategies that capitalize on the targeting ability of anti-GD2 mAbs to potentially deliver, as monotherapy, or in combination with other treatments, improved antitumor efficacy.

Abstract 4013: Transcriptionally mediated effects of radiation on the expression of immune susceptibility markers in murine and human melanoma

Abstract Radiation therapy (RT) may enhance tumor susceptibility to immune response. We and others have observed a cooperative interaction between RT and various immunotherapies, which appears dependent on the relative sequencing of each therapy. We reported a synergistic interaction between RT and the antibody-dependent cell-mediated cytotoxicity (ADCC) response to tumor-specific monoclonal antibodies (mAb) in murine melanoma. We reported enhanced cooperative effect when immunotherapy is administered 6-10 days after RT compared to administration on days 1-5 or 11-15. We hypothesized that this might reflect a delayed, transcriptionally-mediated effect of RT on the expression of tumor markers of immune susceptibility. In this study, we investigated the effect of RT on a variety of immune susceptibility markers at both transcriptional and post-translational levels to explore mechanisms behind the observed RT-induced changes. We used flow cytometry to examine the time course of phenotypic changes in immune susceptibility markers in B78 murine melanoma cells following in vitro RT. We observed a time- and RT dose-dependent increase in the expression of specific death receptors (Fas, DR5), as well as T cell co-stimulatory/co-repressor ligands (PD-L1, CD80). The timing of these changes correlated with tumor susceptibility to ADCC immune response in vivo. All protein expression changes observed by flow cytometry were found to occur over a similar time course by quantitative polymerase chain reaction (qPCR), suggesting that RT-induced protein expression changes were mediated by changes in transcriptional activity. Using high throughput qPCR, we observed a similar time course of transcriptional effects in additional markers of tumor cell immune susceptibility, including Fas, MHC I, CD40, and others. We compared the effect of RT on these markers in human and mouse melanoma cell lines and observed a comparable time course for transcript-level changes across species. This study sheds light on the mechanistic basis of time sensitivity in the interaction of RT with ADCC in vivo and suggests opportunities to enhance anti-tumor immune response by combining RT and immunotherapeutic agents. Such findings bear relevance for research investigating the potential role for RT in driving and optimizing the response to various cancer immunotherapies. Citation Format: Lauryn R. Werner, Monica Gressett, Maureen Riegert, Shyhmin Huang, Joseph G. Kern, Amy Erbe, Paul M. Harari, Paul M. Sondel, Zachary S. Morris. Transcriptionally mediated effects of radiation on the expression of immune susceptibility markers in murine and human melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4013.

Durable antitumor responses to CD47 blockade require adaptive immune stimulation

Therapeutic antitumor antibodies treat cancer by mobilizing both innate and adaptive immunity. CD47 is an antiphagocytic ligand exploited by tumor cells to blunt antibody effector functions by transmitting an inhibitory signal through its receptor signal regulatory protein alpha (SIRPα). Interference with the CD47-SIRPα interaction synergizes with tumor-specific monoclonal antibodies to eliminate human tumor xenografts by enhancing macrophage-mediated antibody-dependent cellular phagocytosis (ADCP), but synergy between CD47 blockade and ADCP has yet to be demonstrated in immunocompetent hosts. Here, we show that CD47 blockade alone or in combination with a tumor-specific antibody fails to generate antitumor immunity against syngeneic B16F10 tumors in mice. Durable tumor immunity required programmed death-ligand 1 (PD-L1) blockade in combination with an antitumor antibody, with incorporation of CD47 antagonism substantially improving response rates. Our results highlight an underappreciated contribution of the adaptive immune system to anti-CD47 adjuvant therapy and suggest that targeting both innate and adaptive immune checkpoints can potentiate the vaccinal effect of antitumor antibody therapy.

Nanoparticle Targeting of Neutrophils for Improved Cancer Immunotherapy.

Cancer immunotherapy using tumor-specific monoclonal antibodies presents a novel approach for cancer treatment. A monoclonal antibody TA99 specific for gp75 antigen of melanoma initiates neutrophil recruitment in tumor responsible for cancer therapy. Here, a strategy is reported for hijacking neutrophils in vivo using nanoparticles (NPs) to deliver therapeutics into tumor. In a mouse model of melanoma, it is shown that systemically delivered albumin NPs increase in tumor when TA99 antibody is injected; and the NP tumor accumulation is mediated by neutrophils. After the administration of pyropheophorbide-a loaded albumin NPs and TA99, photodynamic therapy significantly suppresses the tumor growth and increases mouse survival compared with treatment with the NPs or TA99. The study reveals a new avenue to treat cancer by NP hitchhiking of immune systems to enhance delivery of therapeutics into tumor sites.