Preface

Drug repurposing or drug repositioning is a new approach to presenting new indications for common commercial and clinically approved existing compounds and drugs. Many drugs have been repositioned including minoxidil, a vasodilator approved for treating alopecia (brand name Rogaine) and sildenafil, another vasodilator that is approved for erectile dysfunction (brand name Viagra).

Moreover, we are proposing drug repositioning as a new treatment option to overcome cancer cell resistance or drug resistance in general. In this regard, old drugs seem to be ideal candidates for either reposition or combination therapy with known chemotherapeutic drugs. The development of cancer cell resistance is attributed to different cellular mechanisms such as the development of multidrug resistance (MDR). Therefore, there is no wonder that several research studies have been directed toward the discovery of chemosensitizing agents among commonly available approved drugs that will not only increase the sensitivity of cancer cells but that will also decrease the applied doses of chemotherapeutic drugs and their associated side effects.

Therefore, several scientists have been directed to discover novel compounds that interfere with efflux pumps such as P-glycoprotein and consequently enhance cancer cell sensitivity towards chemotherapeutic drugs. Recently, the old antimalarial drug chloroquine has shown to be a good candidate for treating COVID-19 and interfering with MDR in several types of cancer. Moreover, quinine, which is a known and commercially available natural anti-malarial alkaloid, has been reported for its efficacy as a chemosensitizer in human leukemic cells.

In this book, we focus on the hypothesis, risk/benefits, and economic impacts of drug repurposing on drug discovery in dermatology, infectious diseases, neurological disorders, cancer, and orphan diseases.

More importantly, two chapters explain in full detail the usefulness of simple and cheap chemicals such as fumaric and salicylic acids or their esters for new therapeutic purposes. They address several controversial issues regarding these interesting natural molecules with fascinating multi-pharmacological and therapeutic effects.

This book poses a balance between developments in scientific research and the premises that researchers must be able to absorb and to link scientific advances with clinical practice so that the management of diseases can be based on sound physiological concepts. Each chapter has been reviewed and revised and new authors have brought up-to-date research to make the book informative, illustrative, and easy to read.

**II**

**Section 3**

*by Alkeshkumar Patel*

and Future Perspective

*and Mitsutoshi Nakada*

*and John Robert Paterson*

Broad Potential

*by Matteo Conti*

**Section 4**

Drug Repurposing in Oncotherapeutics

Salicylic Acid Sans Aspirin in Animals and Man *by James Ronald Lawrence, Gwendoline Joan Baxter* 

Drug Repurposing Advances in Oncology **119**

**Chapter 7 121**

**Chapter 8 135**

**Chapter 9 161**

Repositioning of Old Chemicals for New Therapeutic Uses **175**

**Chapter 10 177**

**Chapter 11 197**

Drug Repositioning for the Treatment of Glioma: Current State

*by Sho Tamai, Nozomi Hirai, Shabierjiang Jiapaer, Takuya Furuta* 

Repurposing Infectious Pathogen Vaccines in Cancer Immunotherapy

Repurposing Fumaric Acid Esters to Treat Conditions of Oxidative Stress and Inflammation: A Promising Emerging Approach with

*by Ravirajsinh N. Jadeja, Folami L. Powell and Pamela M. Martin*

We hope this book is useful to a wide range of readers from students newly learning about drug discovery to advanced clinicians, the pharmaceutical industry, and researchers who are looking for a review of current treatments and conceptualizations.
