A Computational Study of Famciclovir Derivatives Against Thymidine Kinase as a Molecular Target for the Development of Novel Anticancer Drugs via Suicide Gene Therapy Concepts

Abstract

Background: The viral thymidine kinase (TK) phosphorylates the antiviral medication famciclovir (FCV), which treats herpes simplex virus (HSV-TK). The phosphorylated FCV destroys the infected cells by preventing cellular DNA synthesis. Objective: We hypothesize that FCV impurity, which is a related substance to FCV, should be efficient in killing cells independent of HSV-TK and is currently the most widely used suicide agent for gene therapy of cancer. Methods: This study proposes the binding affinity of these derivatives for the active site of TK through molecular docking to a protein (PDB ID: 1W4R). The derivatives' reliability was ensured through the in-silico preliminary drug designing model by screening their Lipinski rule of five violations, if any, ADMET prediction for their profile using online tools. Using MOE 2009.10 computational software, we performed molecular docking of approximately 22 famciclovir derivatives alongside the famciclovir drug. Results: Our results suggest that these derivatives are indicative of possible chemical stability irrespective of all the parameters used to evaluate the selected derivatives as a possible drug candidates for their cytotoxicity. FC20 (i.e., 2-(2-(2-((1-(9-(4-Acetoxy-3-(acetoxymethyl)butyl)-2-amino-9Hpurin- 8-yl)ethyl)amino)-9H-purin-9-yl)ethyl)propane-1,3-diyl diacetate) and FC21 (i.e., 2-Amino-1,9- dihydro-9-(4-hydroxybutyl)-6H-purin-6-one), showed maximum and minimum scores of -26.95 and - 7.21 kcal/mol, respectively when compared to famciclovir (-15.4122 kcal/mol). Conclusion: Considering that there might be a cytotoxicity effect due to competition between protein TK and the suicidal gene of famciclovir derivatives. The outcome of the study proved that the FCV impurity could successfully modify an HSV-TK-dependent antiviral drug into an anti-tumor drug. Further, it can be used for the design and development of novel compounds of FCV impurity that could be cytotoxic agents if properly delivered to cancer cells.