Peptide Therapy and The Fight Against Cancer
- Advanced ChemTech offers flexible and economic peptide synthesis services for both solid and solution phase, and can be delivered in various choices of configurations, modifications, and purity.
- The importance of peptides and their role in our pharmaceutical market can be illustrated by this informative article.
The role of peptides in cancer therapy with special emphasis on peptide drugs which are already approved and those in clinical trials is very interesting and making advancement. The potential of peptides in cancer treatment is evident from a myriad of different tactics that are available to address the progression of tumor growth and propagation of cancer. Use of peptides that can directly target cancer cells without affecting normal cells (targeted therapy) is evolving as an alternate strategy to conventional chemotherapy. Peptide can be used directly as a cytotoxic agent through various mechanisms or can act as a carrier of cytotoxic agents and radioisotopes by specifically targeting cancer cells. Peptide-based hormonal therapy has been extensively studied and utilized for the treatment of breast and prostate cancers. Prodigious amount of clinical data is currently available attesting to the efficiency of peptide-based cancer vaccines. Combination therapy is emerging as an important strategy to achieve synergistic effects in fighting cancer as a single method alone may not be efficient enough to produce positive results. Combining immunotherapy with conventional therapies such as radiation and chemotherapy or combining an anticancer peptide with a nonpeptidic cytotoxic drug is an example of this emerging field.
Chemotherapy is one of the prime approaches to treat cancer by delivering a cytotoxic agent to the cancer cells. The main complication with the conventional chemotherapy is the inability to deliver the correct amount of drug directly to cancer cells without impacting normal cells. Drug resistance, altered biodistribution, biotransformation, and drug clearance are also regular problems. Targeted chemotherapy and drug delivery techniques are emerging as a formidable method to bypass such problems. This will allow the selective and effective localization of drugs at predefined targets (e.g., overexpressed receptors in cancer) while restricting its access to normal cell thus maximizing therapeutic index and minimize toxicity.
Discovery of several protein/peptide receptors and tumor-related peptides and proteins is expected to create a “new wave” of more effectual and selective anticancer drugs in the future, seizing the large share of the cancer therapeutic market. The “biologics” treatment alternative against cancer includes the use of proteins, monoclonal antibodies, and peptides. The monoclonal antibodies (mAbs) and large protein ligands have two major limitations compared to peptides: poor delivery to tumors due to their large size and dose-limiting toxicity to the liver and bone marrow due to nonspecific uptake into the reticuloendothelial system. The use of such macromolecules has therefore been restricted to either vascular targets present on the luminal side of tumor vessel endothelium or hematological malignancies. Peptides possess many advantages, such as small size, ease of synthesis and modification, tumor-penetrating ability, and good biocompatibility . Peptide degradation by proteolysis can be prevented by chemical modifications such as incorporation of D-amino acids or cyclization.
Current peptide drugs available in the market for treating cancer and also peptide candidates in clinical and preclinical stages of development. Peptides can be utilized in a number of different ways in treating cancer. This includes using peptides directly as drugs (e.g., as angiogenesis inhibitors), tumor targeting agents that carry cytotoxic drugs and radionuclides (targeted chemotherapy and radiation therapy), hormones, and vaccines. Different possible cancer treatment options using peptides are summarized in the figure below. Due to the ability to bind to different receptors and also being part of several biochemical pathways, peptides act as potential diagnostic tool and biomarkers in cancer progression. Out of these different possibilities, peptide drugs currently available in the market come from peptide hormone therapy and tumor targeting agents carrying radionuclides (peptide-receptor radio nuclide therapy and imaging).
There is a colossal progression in other areas such as peptide-vaccine development and peptide angiogenesis inhibitors, and multiple clinical trials are underway which is expected to succeed in near future providing better options to millions of cancer patients.
Journal of Amino Acids Volume 2012 (2012), Article ID 967347, 13 pages http://dx.doi.org/10.1155/2012/967347