Targeting T Cells with Bispecific Antibodies for Cancer Therapy

Bispecific antibodies (BiAbs) offer a unique opportunity to redirect immune effector cells to kill cancer cells. BiAbs combine the benefits of different binding specificities of two monoclonal antibodies (mAbs) into a single construct. This unique feature of BiAbs enables approaches that are not possible with single mAbs. Advances in antibody engineering and antigen profiling of malignant cells have led to the development of a number of BiAb formats and their combinations for redirecting effector cells to tumor targets. There have been significant advances in the design and application of BiAbs for intravenous and local injection.The initial barrier of cytokine storm has been partially overcome by more recent constructs that have improved clinical effectiveness without dose-limiting toxicities. Since the recent revival of BiAbs, there has been multiple, ongoing, phase I/II and III trials, and some promising clinical outcomes have been reported in completed clinical studies. This review focuses on arming T cells with BiAbs to create the 'poor man's cytotoxic lymphocyte'.     

Bispecific Antibodies for Cancer Immunotherapy

The concept of using bispecific antibodies to retarget immune effector cells for cancer therapy was conceived more than 20 years ago. However, initial clinical studies were rather disappointing mainly due to low efficacy, severe adverse effects and immunogenicity of the bispecific antibodies. A deeper understanding of effector cell biology and especially developments in the field of antibody engineering has led to the generation of new classes of bispecific antibodies capable of circumventing many of these obstacles. Furthermore, new applications were established for bispecific antibodies, such as pre-targeting strategies in radioimmunotherapy or dual targeting approaches in order to improve binding, selectivity, and efficacy. This review summarizes recent progress in the development of bispecific antibodies and describes some new concepts developed for cancer immunotherapy.     

Modulation of Cancer Patients' Immune Responses by Anti-idiotypic Antibodies

The immunomodulatory role of anti-idiotypic antibodies (Ab2) in patients with gastrointestinal cancer has been demonstrated in two types of clinical trials. In the first, cancer patients were treated with a monoclonal antibody (MAb) defining a tumor-associated antigen (Ag). MAb administration initiated an idiotypic network as demonstrated by the induction of both Ab2 and anti-anti-idiotypic antibodies (Ab3) in the treated patients. The Ab3 bound to tumor cells and isolated tumor Ag with the same specificity as the Mab (Ab1) at the beginning of the idiotypic cascade. A beneficial role of Ab3 is postulated for patients showing delayed clinical responses to MAb therapy.

In a recent trial, patients with advanced colorectal cancer responded to immunization with Ab2 that functionally mimicked in vitro and in vivo (animals) a gastrointestinal tumor-associated Ag by developing highly specific Ab3 with anti-tumor binding reactivities. Thus, Ab2 are promising agents in immunotherapy approaches to cancer. These studies suggest an immunoregulatory role for Ab2 in cancer patients. Modulation of cellular immune responses by Ab2 in cancer patients will be an important consideration in future studies.     

Enhancement of Immune Function and Tumor Growth Inhibition by Antibodies Against Prostaglandin E2

Mice bearing a Lewis lung carcinoma (LLC) were passively immunized against prostaglandin E₂ (PGE₂ by administration of rabbit serum containing anti-PGE₂ antibodies. The effect of PGE₂-inxnune serum on the suppressed imnunity of LLC-bearing mice was examined. Treatment of tumor-bearing mice with anti-PGE₂ prevented the suppression of lymphocyte mito-genesis and the alterations in macrophage migration which typically occur in LLC-bearing mice. Furthermore, tumor growth was reduced In LLC-bearing mice which received antibodies directed against PGE₂ rather than a placebo treatment.     

Natural Immunity has Significant Impact on Immune Responses Against Cancer

The immune system defends the host against pathogenic attacks by micro-organisms and their products. It does not react against self-components due to the relatively efficient negative selection of developing T lymphocytes in the thymus. This process does permit T cells with low avidity against self to be present in the T cell repertoire. Such cells play an important physiological role as the host needs so-called autoimmune reactions in order to eliminate dying cells or transformed tumour cells. One of the mysteries in immunology is how the host maintains beneficial autoimmune reactions and avoids pathogenic autoimmune reactions. Activation of the adaptive T lymphocytes is mediated by the low avidity interaction between T-cell antigen receptors and antigenic peptides associated with major histocompatibility complex class I or class II molecules. This interaction is strengthened by T-cell co-receptors such as CD2, CD4, CD8, CD28 and CD154, which react with ligands expressed by cells of the innate immune system. In recent years, the importance of pre-activation of the innate immune system for initiation of adaptive T-cell immune responses has been appreciated. In the present review, I will summarize our work on how natural immunity plays an important role in determining the level of beneficial autoimmune reactions against cancer.     

靶向CD20和HLA-DR分子Crossmab的设计与构建表达

目的设计、构建与表达靶向CD20和HLA-DR分子的Crossmab双特异性抗体。方法设计靶向CD20和HLA-DR分子的Crossmab双特异性抗体分子,命名为CD20-HLA-DR CrossmabCH1-CL,利用基因工程技术构建Crossmab四条链的真核表达载体,然后利用FreeStyle 293-F Cells哺乳动物细胞表达体系表达CD20-HLA-DR CrossmabCH1-CL。结果获得了CD20-HLA-DR CrossmabCH1-CL抗体分子蛋白。结论成功设计、构建、表达并初步鉴定了靶向CD20和HLA-DR分子的双特异性抗体CD20-HLA-DR CrossmabCH1-CL,为研制新型抗肿瘤的双特异性抗体药物打下了基础。     

Lactobacillus acidophilus Could Modulate the Immune Response Against Breast Cancer in Murine Model

Cancer immune-therapy is an interesting avenue of studying the effects of deviating immune system responses to achieve the desired result. Lactobacilli are inhabitants of the GI tract which have shown beneficial health effects on various ailments including malignancies. Their mechanisms of action comprise a very intense area of research. In this study we evaluated the immunomodulatory effects of Lactobacillus acidophilus in in vivo model of breast cancer. Lactobacillus acidophilus (L.a) was isolated from traditional home-made yogurt and also from neonatal stool by aerobic overnight culture at 37°C in MRS broth. Delayed Type Hypersensitivity (DTH) assay was performed to find the best immunostimulant dose. 4T1 tumour bearing mice were treated with 2?×?10⁸ cfu of isolated L. acidophilus and 20 mg/kg Cyclophosphamide for 15 consecutive days. Tumour volume was measured using a digital vernier calliper. Lymphocyte proliferation was done using MTT proliferation assay. Production of IFNγ, IL-4 and TGF-β from cultured Splenocytes was assessed in the presence of purified tumour antigen. According to results administration of L.a induced a significant decrease in tumour growth pattern (P value?=?0.00). Significant alterations in splenocyte production of IFN-γ, IL-4 and TGf-β (P values?<?0.05) and also lymphocyte proliferation in L.a treated animals was evident (P value?<?0.05). This study indicated that oral administration of L.a is able to alter the cytokine production in tumour bearing mice into a Th1 protective pattern, favourable to anti tumour immunity. Reduced tumour growth rate and increased lymphocyte proliferation are also thus supportive. Further studies are required to elucidate the exact mechanism by which local actions of probiotics affect the systemic immune responses against transformed cells.     

Multi-Specific Antibodies for Cancer Immunotherapy

Targeted treatment of cancer with monoclonal antibodies has added to the beneficial outcome of patients. In an attempt to improve anti-tumor activity of monoclonal antibodies, multi-specific antibodies have entered the research arena. To date, only a few multi-specific constructs have entered phase III clinical trials, in contrast to classical monoclonal antibodies, which are the standard first-line therapy in several tumor entities. In this review, we will assess selected multi-specific antibodies in pre-clinical and clinical development that may be new treatment options for cancer patients in the very near future. We will further evaluate therapy modalities including the timely distribution or the combination of various therapeutic approaches and assess the potential role of multi-specific antibodies in cancer treatment.     

人肺癌单克隆抗体的制备及其抗原分子的鉴定

用人肺癌细胞株A549的细胞膜蛋白作为免疫原,采用杂交瘤技术成功制备了抗人肺癌细胞单克隆抗体McAb4E7,并利用双向电泳、免疫印迹杂交、肽指纹图谱和MALDI-TOF-MS串连质谱分析鉴定其相关抗原分子,发现其相关抗原在人肺癌细胞株A549及人肝癌细胞株HepG2中有表达,且在A549细胞中表达量较高。最后得到一个在A549细胞中表达的与单克隆抗体McAb4E7特异性结合的蛋白,并鉴定出这个蛋白是ATP合成酶β亚基,从而证明了ATP合成酶β亚基就是肺癌单克隆抗体McAb4E7的靶抗原,其可作为肺癌具有潜在治疗意义的靶点。     

Broadly Neutralizing Antibodies as Treatment: Effects on Virus and Immune System

Purpose of Review

The purpose of this study is to summarize recent advances in the use of broadly neutralizing antibodies (bNAbs) as therapeutics in human clinical trials and in non-human primate (NHP) models. We seek to highlight lessons from these studies with an emphasis on consequences to the virus and immune system.

Recent Findings

In the past 10 years, advances in HIV-1 trimer structure and B cell isolation methods have precipitated the identification of “new-generation” anti-HIV antibodies with broad and potent neutralization. In the past 2 years, the concept of using these bNAbs as therapeutic tools has moved from NHP models into human clinical trials. These trials have investigated the effects of bNAb infusions into patients chronically infected with HIV-1, while the NHP model has investigated treatment during acute infection.

Summary

Through this work, the relationship between in vitro breadth and potency and in vivo clinical effect, although unresolved, is gradually being elucidated. These results emphasize the need for combination antibody therapy.

     

运动神经元单克隆抗体的制备及初步鉴定

以猪脊髓前角运动神经细胞制备的匀浆免疫Ｂａｌｂ／ｃ小鼠。按常规方法制备、筛选抗运动神经元单克隆抗体。总计３５株杂交瘤细胞所分泌的ＭｃＡｂ，与大鼠半月神经节细胞免疫组化反应均呈阴性，３０株与脊髓前角运动细胞（Ｍｎ）呈阳性反应、其中５株ＭｃＡｂｓ免疫组化反应特异性较强，用ＥＬＩＳＡ方法测定其滴度在２０４８～４０９６之间，免疫双扩散法测定，５株杂交瘤均分泌ＩｇＧ。     

Anti-Cardiolipin and Anti-Phosphatidylglycerol Antibodies Prepared Against Bacterial Phospholipids

Anti-phosphatidylglycerol and anti-cardiolipin antisera were prepared in rabbits by using phospholipids purified from Micrococcus lysodeikticus. Anti-phosphatidylglycerol antibodies were found in antisera when either phosphatidylglycerol or cardiolipin were used as immunogens, but adsorption studies indicated they were not similar. Antibodies which reacted with phosphatidylinositol and phosphatidic acid were also found in the anti-cardiolipin antiserum. Structures of the antigenic groups in phosphatidylglycerol and cardiolipin are suggested from cross-reaction and adsorption studies. Adsorption studies with pure phospholipid antigens indicated the importance of the spacial orientation of phospholipid haptens for immunological reactivity.     

Monoclonal Antibodies Against a Sulfathiazole Derivative for the Immunochemical Detection of Sulfonamides

To prepare monoclonal antibodies (mAbs) against the generic part of sulfonamides, a sulfathiazole derivative was chemically linked to carrier proteins in such a way that the aromatic amino group, common to all sulfonamides, was distal to the proteins. Four mice were immunized with the sulfathiazole-protein derivatives. The spleen cells of one of the mice were fused with myeloma cells to produce hybridomas of which the supernatants were screened in an indirect ELISA (iELISA) for the presence of sulfathiazole antibodies. After cloning, positive supernatants were tested in a competitive iELISA (ciELISA) for inhibition with 18 sulfonamides. This resulted in four different mAbs (all IgG1 kappa light chain) which recognized several sulfonamides. By use of the best monoclonal (27G3) and an optimized ciELISA protocol, eight structurally different sulfonamides showed 50% inhibition at concentrations less than 100 ngml^- or 5 ng/well. However, other relevant sulfonamides (such as sulfadimidine, sulfatroxazole and sulfachloropyrazine) were detected at a high level only with this mAb. This means that the ciELISA (with the best Mab) showed a broad specificity for sulfonamides but the sensitivity towards the different sulfonamides varied too much to call it a generic sulfonamide ELISA.