Molecularly targeted therapy

Molecularly Targeted Therapy

Molecularly targeted therapy is a type of medical treatment that uses drugs or other substances to precisely identify and attack specific types of cancer cells, usually by interfering with specific molecules involved in the growth, progression, and spread of cancer. This approach is part of the broader field of precision medicine, which aims to tailor medical treatment to the individual characteristics of each patient.

Mechanism of Action

Molecularly targeted therapies work by targeting specific molecules that are involved in the growth and survival of cancer cells. These molecules are often proteins that are overexpressed or mutated in cancer cells. By inhibiting these targets, the therapies can block the growth and spread of cancer cells while minimizing damage to normal cells.

Some common targets for these therapies include:

• Receptor Tyrosine Kinases (RTKs): These are high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Examples include the epidermal growth factor receptor (EGFR) and the vascular endothelial growth factor receptor (VEGFR).
• Signal Transduction Pathways: These pathways transmit signals from the cell surface to the DNA in the nucleus. Targeting components of these pathways, such as the PI3K/AKT/mTOR pathway, can inhibit cancer cell growth.
• Apoptosis Regulators: Some therapies aim to induce apoptosis, or programmed cell death, in cancer cells by targeting proteins that regulate this process, such as Bcl-2 family proteins.

Types of Molecularly Targeted Therapies

Molecularly targeted therapies can be classified into several types based on their mechanism of action:

• Monoclonal Antibodies: These are laboratory-produced molecules that can bind to specific antigens on cancer cells. Examples include trastuzumab for HER2-positive breast cancer and rituximab for certain types of lymphoma.
• Small Molecule Inhibitors: These are compounds that can enter cells easily and interfere with the function of specific proteins. Examples include imatinib for chronic myeloid leukemia and erlotinib for non-small cell lung cancer.
• Antibody-Drug Conjugates (ADCs): These are monoclonal antibodies linked to cytotoxic drugs. The antibody targets the cancer cell, delivering the drug directly to it. An example is ado-trastuzumab emtansine for HER2-positive breast cancer.

Advantages and Limitations

Advantages

• Specificity: Targeted therapies are designed to specifically target cancer cells, which can reduce damage to normal cells and decrease side effects compared to traditional chemotherapy.
• Personalization: These therapies can be tailored to the genetic profile of a patient's tumor, potentially increasing their effectiveness.

Limitations

• Resistance: Cancer cells can develop resistance to targeted therapies, often through mutations in the target or activation of alternative pathways.
• Limited Targets: Not all cancers have identifiable targets that can be exploited by current therapies.

Clinical Applications

Molecularly targeted therapies have been approved for the treatment of various cancers, including:

• Breast cancer
• Lung cancer
• Colorectal cancer
• Melanoma
• Leukemia

Research and Development

Ongoing research is focused on identifying new targets, developing new drugs, and overcoming resistance mechanisms. Advances in genomics and proteomics are aiding in the discovery of novel targets and the development of more effective therapies.

Also see

• Precision medicine
• Cancer immunotherapy
• Chemotherapy
• Monoclonal antibody therapy

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