Tumor Antigen Overview

Tumor antigens are targets for immunotherapy, such as:
- Monoclonal antibodies (e.g., trastuzumab targeting HER2).
- Cancer vaccines (e.g., sipuleucel-T for prostate cancer).
- CAR T-cell therapies targeting specific antigens (e.g., CD19).
Enhance immune system's ability to recognize and destroy cancer cells.

Techniques include:
- Genomic and proteomic profiling to identify unique surface proteins on tumor cells.
- Use of high-throughput sequencing and bioinformatics.
- Identification of neoantigens arising from tumor mutations.
Focus on finding antigens that elicit strong immune responses.

Tumor antigens can induce both humoral (antibody-mediated) and cellular (T-cell mediated) immune responses.
Immune evasion mechanisms by tumors include:
- Downregulation of antigen presentation.
- Secretion of immunosuppressive factors.
- Induction of regulatory T cells.
Effective therapies aim to overcome these barriers to enhance immune response.

Tumor-Specific Antigens (TSAs):
- Unique to cancer cells, not found on normal cells (e.g., mutated proteins).
Tumor-Associated Antigens (TAAs):
- Present on both tumor and normal cells, often overexpressed in tumors (e.g., HER2, CEA).
Neoantigens:
- Result from tumor-specific mutations; highly immunogenic and personalized.
Viral Antigens:
- Associated with virus-induced cancers (e.g., HPV antigens in cervical cancer).
Oncofetal Antigens:
- Normally expressed during fetal development but re-expressed in tumors (e.g., alpha-fetoprotein, AFP).

Tumor antigens are crucial indicators for detecting cancer and monitoring its progression.
Blood tests utilize tumor antigens, such as PSA for prostate cancer and CA-125 for ovarian cancer.
Early detection of cancer and assessment of treatment effectiveness are facilitated by these biomarkers.
High specificity and sensitivity of tumor antigen tests are essential for successful diagnostics.

Tumor antigens are primary targets in various immunotherapy approaches.
Monoclonal antibodies like trastuzumab specifically target HER2 protein in breast cancer treatment.
Cancer vaccines, such as sipuleucel-T, are designed to stimulate an immune response against prostate cancer.
CAR T-cell therapies target defined antigens, exemplified by CD19 in certain blood cancers.
These therapies enhance the immune system's ability to recognize and eliminate cancer cells.

Genomic and proteomic profiling techniques identify unique proteins on tumor cell surfaces.
High-throughput sequencing and bioinformatics play significant roles in the discovery process.
Neoantigens, which arise from mutations specific to tumor cells, are a primary focus due to their strong immune response potential.
The aim is to identify antigens that elicit robust immune reactions for effective targeting.

Tumor antigens can trigger both antibody-mediated (humoral) and T-cell mediated (cellular) immune responses.
Tumors employ immune evasion strategies to avoid detection, including:
- Downregulation of antigen presentation to immune cells.
- Secretion of factors that suppress immune responses.
- Induction of regulatory T cells that inhibit immune activity.
Therapeutic strategies aim to counteract these immune evasion mechanisms to strengthen immune responses against tumors.

Tumor-Specific Antigens (TSAs): Exclusive to cancer cells, often arising from mutated proteins and not present on normal cells.
Tumor-Associated Antigens (TAAs): Found on both tumors and normal cells, frequently overexpressed in cancer (e.g., HER2, CEA).
Neoantigens: Result from specific mutations in tumors; recognized as highly immunogenic and pivotal for personalized therapies.
Viral Antigens: Linked to cancers associated with viruses, such as HPV in cervical cancer.
Oncofetal Antigens: Normally expressed during fetal development but reappearing in certain tumors, such as alpha-fetoprotein (AFP).