Dr. Jacek Cieslak is a product quality team leader in the Office of Biotechnology Products (OBP), Office of Pharmaceutical Quality (OPQ), CDER, FDA. Between 2005 and 2014, Dr. Cieslak has been working at FDA as a researcher/reviewer in the Division of Therapeutic Proteins in OBP where he gained review experience including protein therapeutics and biosimilar products. Dr. Cieslak joined the FDA in 2001 where he conducted his postdoctoral research on chemical synthesis and modifications of oligonucleotides. Prior to joining the FDA, he earned his Ph.D. degree in Chemistry from the Polish Academy of Sciences. He has authored and co-authored over 40 peer-reviewed publications in the area of oligonucleotide synthesis.