Challenges of aptamers as targeting ligands for anticancer therapies

Cancer is a most prevalent diseases condition in human beings and it stands at second position among the most widespread noncommunicable diseases worldwide. As per recent database, cancer is causing mortality of 10 million in the world. This has persuaded the scientific community to look for newer and better cancer management methods. Among recent trends, immunotherapy-based approaches have gained significant attention for cancer therapy. These molecular ligands hold tremendous promise in the field of cancer diagnosis and therapeutics. Toward this, aptamers are valuable for targeting specific cells or initiating a functional response by binding and internalization with the aid of receptor molecules found on the surface of cancer cells. Aptamers are about 20–80 nucleotides long, RNAs or single-stranded DNAs. Systematic Evolution of Ligands by Exponential Enrichment is an iterative method for the generation of aptamers. The last few decades have witnessed the generation of aptamers for use against a variety of tumor markers such as tenascin, nucleolin, annexin A2, and prostate-specific membrane antigen Aptamers can be used for targeted delivery of another drug, antibody or nanoparticle for treatment of cancer. Aptamers with therapeutic potential have been generated against various forms of cancer such as prostate cancer, renal cancer, cervical carcinoma, stomach carcinoma and bladder carcinoma. Moreover, aptamers have certain drawbacks like fast renal clearance rate and are prone to degradation by nucleases present in the cell. Thus, to overcome these lacunae, various biochemical approaches have been used to increase the stability of aptamers in vivo and increase their pharmacodynamic and pharmacokinetic properties.