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Our immune system is the first line of defense against any disease; however, diseases such as cancer require additional intervention to strengthen the immune response. Cancer immunotherapy has emerged as a strategy to target cancer by either (a) directing immune cells to target specific, distinguishable molecules on cancer cells or (b) interfering with signaling pathways that would either inhibit cell growth or dampen immune system activity.
In order to develop effective therapeutics that meet either of these strategies, identification of therapeutic targets is required. For example, PD-1 And PD-L1 are well established antibody targets that function as immune checkpoints to downregulate immune responses against tumors. Anti-PD-1 antibodies have since been developed to mediate antitumor activity. Therefore, identifying the appropriate targets and the subsequent design of effective antibodies or gene therapies are integral to the development of cancer immunotherapies.
Cancer immunotherapy using antibodies relies on recruiting elements in the immune system to produce a therapeutic effect. For example, although antibody binding to a specific epitope of a cell surface receptor can directly induce apoptotic signals, the effect is usually amplified by cross-linking of the antibody Fc domains through binding to Fc receptors on immune effector cells, such as macrophages and NK cells. Concomitantly, the immune effector cells are activated by engagement of the Fc receptors. This results in an attack on the cells to which they are bound, a process known as antibody-dependent cell mediated cytotoxicity (ADCC). The Fc domains can also activate the complement system, causing complement-dependent cytotoxicity (CDC). Not sure which antibody service is right for your cancer immunotherapy application? Learn more
The use of recombinant antibody technology has led to an enormous growth in the use of antibodies as agents in cancer immunotherapy. For example the single chain variable fragments (scFv) are shown to retain their full binding specificity and affinity. scFv fusions can be used to link scFv to toxins, enzymes, cytokines or chemokines. Recombinant antibody fragments are also being generated as bispecific molecules to target human cytoxotic T cells or NK cells. There are several antibody formats that can be used for the purpose of cancer immunotherapy. GenScript has launched a suite of Recombinant Antibody Services for research surrounding cancer immunotherapy. View our Service Selection Guide to choose from services that deliver between micrograms to gram quantities of pure recombinant antibody for each stage of your cancer immunotherapy, antibody drug discovery program.
Tumor associated antigens (TAAs) are peptide sequences that are recognized by CD8+ T-cells as “non-self” .Detection of these antigens vastly increases immune system activity to eradicate cells that present these antigens, or tumor cells, and thus are a major focus for cancer immunotherapy. To amplify the immune response, T cells have been engineered ex-vivo to specifically recognize these antigens, and ultimately the more specifically they recognize the antigen, the better. Many cancer immunotherapy studies have focused on identification of specific epitopes on these antigens or T cell engineering. Peptide Libraries are often used in these studies to narrow down the most important, immunostimulatory sequences. Once identified, researchers can genetically alter the T cell receptor to identify this epitope, creating chimeric antigen receptor-modified T cells, or CAR-T cells. Making better T cells, such as CAR-T cells, is quickly becoming one of the most promising targeted cancer immunotherapy strategy. Learn more about designing peptide libraries for cancer immunotherapy applications
An important component of cancer therapy is finding new methods to detect it earlier and non-invasively. In this study, researchers sought B-cell epitopes that would target Sox2, a transcription factor that plays an important role in cancer stem cell activities. A computer-assisted algorithm was used to predict the dominant B-cell epitopes for Sox2, and these peptides were synthesized using GenScript’s Peptide Services. The authors discovered that serum samples from a range of cancer patients recognized these synthesized epitopes. Their findings could eventually be applied to novel cancer immunotherapies.
Shih et al.Dominant B-cell epitopes from cancer/stem cell antigen Sox2 recognized by serum samples from cancer patients.
Am J Clin Exp Immunol. 2014 Aug; 3 (2): 84-90.
Naturally occurring T cells that target tumor cells are insufficient for mounting an adequate immune response. In this study, Peptide Libraries were used to help design T cell receptors that target cancer peptides MART1/HLA-A2. Development of these engineered T cell clones will improve specificity of TCRs for peptide antigens on cancer cells.
Tittarelli et al. Smith et al. Changing the peptide specificity of a human T-cell receptor by directed evolution. Nat Commun. 2014 Dec.
The ErbB2 protein is overexpressed in numerous cancers, including breast cancer. ErbB2 is immunogenic, therefore researchers sought to determine whether inoculation with purified recombinant ErbB2 could confer protective immunity against mammary cancer in a mouse model of breast cancer. Codon optimization and gene synthesis from GenScript were used to generate three different variants of the immunogenic extracellular domain of ErbB2, which were then expressed in the plant Nicotiana benthamiana, a highly tractable model organism. The ErbB2 variant with the highest expression level was solubilized, purified, and administered to healthy mice, which showed ErbB2-specific immune responses after administration; vaccinated mice were protected from a later challenge with syngeneic transplantable ErbB2+ mammary carcinoma cells, indicating that the recombinant ErbB2 vaccine induced potent antitumor activity by the immune systems of vaccinated mice.
Matic et al. The rat ErbB2 tyrosine kinase receptor produced in plants is immunogenic in mice and confers protective immunity against ErbB2+ mammary cancer. Plant Biotechnology Journal. 2015 Apr 10. doi: 10.1111/pbi.12367. Full Text.
To develop adoptive immunotherapy strategies for treating cancer, researchers look for antigens that are specifically expressed by tumor cells but are not expressed by normal cells in tissues that are essential for patient health. In one study, researchers focused on SSX2, a protein that is classified as a cancer-testis antigen. SSX2 is highly expressed in melanoma, prostate cancer, lymphoma, multiple myeloma, pancreatic cancer, and other types of tumor cells, but is absent in healthy tissues with the exception of non-MHC expressing germ cells of testis; because these testic cells do not generally present antigens to T-cells, SSX2 is expected to be a safe and efficacious target against which to engineer T-cells to specifically recognize tumor cells in a wide variety of cancer types. When constructing retroviral vectors to introduce novel receptors targeting SSX2 into T-cells, they found that Codon Optimization of the vectors increased the expression of recombinant T-cell receptors in transduced T cells and enabled potent antigen-specific reactivity against SSX2. Further optimization of the TCR nucleotide sequence enabled the development of clinical-grade retroviral vector producer cell line for future use in adoptive immunotherapy clinical trials.
Abate-Daga et al. Development of a T Cell Receptor Targeting an HLA-A*0201 Restricted Epitope from the Cancer-Testis Antigen SSX2 for Adoptive Immunotherapy of Cancer. PLoS One. 2014 Mar 28;9(3):e93321. doi: 10.1371/journal.pone.0093321. eCollection 2014.
For your downstream Antibody Drug Development, GenScript offers a full spectrum of services, from initial hybridoma development all the way to recombinant antibody production. If your target antigen is difficult to express in vitro, DNA immunization can be the alternative approach for animal immunization, enabling protein antigen expression in vivo.
Altering key immune-checkpoint proteins can enhance the immune system’s activity against tumor cells. The cell-based immune-checkpoint assay service at GenScript provides a variety of engineered stable cell lines o support assay development. GenScript also provides multiple syngeneic mouse tumor models to facilitate your drug discovery.
GenScript’s GenEZ™ ORF clones can be used for transient expression of target receptors like PD1 or other co-stimulatory ligands such as CD275 in the study of immune checkpoint pathway signaling and interactions. ORF clones come in our signature pcDNA3.1+-DYK vector or in your expression-ready vector of choice. ORF Mutant Clones and plasmid preparations can also be made from ORF clones to further customize your assays.
GenScript’s Custom Peptide Synthesis service is ideal for both epitope screening and development of highly specific antibodies. Modifying T cells to recognize specific cancer cell epitopes is an important component of cancer immunotherapy. Peptide Libraries make it easier to screen hundreds of peptide combinations to identify stimulatory regions. Crude, Overlapping Peptide Libraries are ideal for these applications.
In order to efficiently generate antigenic proteins, chimeric T-cell receptors, and other immune-modulating biomolecules for cancer immunotherapy research, researchers rely upon codon-optimized gene synthesis to create expression constructs. Codon Optimization maintains the desired amino acid sequence of the protein product while adjusting the nucleotide sequence of the DNA construct to favor efficient transcription, mRNA stability, translation, and proper protein folding. Gene Synthesis enables any wild-type, mutant, chimeric, or custom-designed DNA sequence to be generated quickly and with 100% sequence accuracy. VectorArk™ Cloning allows easy, cost-efficient cloning of synthetic gene inserts into any vector to deliver expression-ready clones.