About
About Sio
Sio Gene Therapies is a clinical-stage company with a singular focus on pushing the boundaries of gene therapy to develop treatments for debilitating rare neurodegenerative diseases, including GM1 gangliosidosis and Tay-Sachs/Sandhoff disease.
Sio is leveraging its foundational scientific expertise built on decades of research, extensive collaborations with leading gene therapy institutes, and a flexible vector platform to liberate patients with debilitating diseases through the transformational power of gene therapies.
Our mission is simple:
To combine cutting-edge science with bold imagination to develop genetic medicines that aim to radically improve the lives of patients. We are working tirelessly to advance our rare fatal pediatric neurodegenerative programs through clinical development so that patients can access the therapies they need.
Management
Our team is made up of leading scientific and gene therapy experts with decades of experience in all stages of drug development and commercialization. Our leaders are passionate about treating life-limiting neurodegenerative diseases on behalf of patients and their families.

David Nassif, JD

Raquel Crystal
David Nassif, JD
Chief Executive Officer, Chief Financial Officer & General Counsel
David Nassif, JD, serves as Chief Executive Officer, Chief Financial Officer and General Counsel at Sio. He has more than 25 years of life sciences industry experience in executive financial management roles in development-stage, commercial-stage, public and private companies. Prior to joining Sio, Mr. Nassif was Executive Vice President and Chief Financial Officer of SteadyMed Therapeutics, where he was instrumental in its acquisition by United Therapeutics in August 2018. From 2011 to 2014, Mr. Nassif served as the President and Chief Financial Officer of Histogen. Previously, he was Executive Vice President and Chief Financial Officer of Zogenix and held several key roles at Amphastar Pharmaceuticals and RealAge Inc. Earlier in his career, Mr. Nassif held various positions with Cypros Pharmaceuticals, where he was instrumental in leading its merger with Ribogene, Inc. to form Questcor Pharmaceuticals, Inc. He holds a BS in finance and management information systems with honors from the University of Virginia and a JD from the University of Virginia School of Law.
Raquel Crystal
Head of Human Resources & Operations
Raquel Crystal serves as Head of Human Resources & Operations at Sio. Ms. Crystal has over 15 years of human resources experience across different industries including financial technology and financial services. She previously served as Head of Human Resources and Talent Acquisition at Roivant Sciences, Inc. Prior to that, Ms. Crystal was the Head of Human Resources at CoreOne Technologies, a financial technology firm, covering Europe, Asia and North America. She also held multiple roles in human resources at Morgan Stanley and Ambrose Employer Group. She holds a BS in Industrial and Labor Relations from Cornell University.
Board of Directors

Frank Torti, MD

Atul Pande, MD

Eric Venker, MD, PharmD

Kristiina Vuori, MD, PhD

Berndt Modig

Senthil Sundaram

David Nassif, JD
Frank Torti, MD
Chairperson of the Board of Directors
Dr. Torti has served as a member of our board since September 2018. Since January 2020, Dr. Torti served as the Vant Chair of Roivant Sciences, Inc. (RSI), where he previously worked as Vant Investment Chair. Prior to joining RSI, Dr. Torti served as a Partner of New Enterprise Associates (NEA), specializing in investments in healthcare. Before NEA, Dr. Torti worked for the Duke University Center for Clinical & Genetic Economics, where he was involved in clinical trials research and economic evaluations of multinational clinical trials. Dr. Torti presently serves as Chairperson of the board of directors of Immunovant, Inc., Arbutus Biopharma Corp. and several private biopharmaceutical companies. Dr. Torti earned an MD from the University of North Carolina School of Medicine, an MBA from Harvard Business School and a BA from the University of North Carolina.
Atul Pande, MD
Lead Independent Director
Dr. Pande has served as a member of the Sio board since March 2015. He serves as Chief Medical Advisor of PureTech Health, President of Verity BioConsulting, a drug development consulting firm, and Chief Medical Officer of Tal Medical, a clinical-stage medical device company. From 2007 to April 2014, Dr. Pande was Senior Vice President and Senior Advisor, Pharmaceutical R&D, at GlaxoSmithKline. He has also held senior roles at Pfizer R&D, Parke-Davis/Warner-Lambert and Lilly Research Laboratories. Dr. Pande is also a non-executive board member of Autifony Therapeutics and Karuna Pharmaceuticals. Dr. Pande received a Bachelor of Medicine, Bachelor of Surgery (MBBS) degree from the University of Lucknow, India, and completed his research fellowship training in psychiatry at the University of Michigan Medical School and postgraduate specialty training and psychiatry residency program at Western University.
Eric Venker, MD, PharmD
Eric Venker has served as a member of the Sio board since February 2020. He serves as Chief Operating Officer of Roivant Sciences. Dr. Venker first joined Roivant in 2014 and has since served in various roles of increasing responsibility, including Chief of Staff to the CEO. Prior to joining Roivant, Dr. Venker was a physician at New York Presbyterian Hospital, Columbia University Medical Center, where he trained in internal medicine. While there, Eric served as the Chair of the Housestaff Quality Council and led operational initiatives to improve efficiencies across a large hospital system with $5 billion in annual revenue. Earlier in his career, Eric was a Clinical Pharmacist at Yale-New Haven Hospital. He received his PharmD from St. Louis College of Pharmacy and his MD from Yale School of Medicine.
Kristiina Vuori, MD, PhD
Dr. Vuori has served as member of our board since October 2020. Since January 2010, Dr. Vuori has served as President and member of the Board of Directors of Sanford Burnham Prebys Medical Discovery Institute (SBP), one of the largest non-profit biomedical research centers in the U.S. with a focus on cancer, neurodegeneration, inflammatory and infectious diseases, heart disease and rare children’s disorders. Since January 1995, Dr. Vuori has also served as a Professor at SBP’s National Cancer Institute-designated Cancer Center. Previously, she served as SBP’s EVP for Scientific Affairs in 2008-2010, as Director of the Cancer Center in 2005-2013, and as Deputy Director of the Cancer Center in 2003-2005. Dr. Vuori currently serves or has served on the Board of Directors for American Association for Cancer Research, California Institute for Regenerative Medicine, California Breast Cancer Research Program, Sanford Consortium for Regenerative Medicine, UCSD Sanford Stem Cell Clinical Center, and Bionano Genomics, Inc. She was director of WebMD, Inc. until it was sold to KKR in 2017. Dr. Vuori holds M.D. and Ph.D. degrees from University of Oulu, Finland.
Berndt Modig
Modig has served as a member of the board since March 2015. He also serves as Chief Executive Officer of Pharvaris N.V. Previously, he served as Chief Financial Officer of Prosensa Holding N.V., a pharmaceutical company, from March 2010 until its acquisition by BioMarin Pharmaceutical Inc. in January 2015. From October 2003 to November 2008, Mr. Modig was Chief Financial Officer at Jerini AG where he directed private financing rounds, the company’s initial public offering in 2005, and its acquisition by Shire plc in 2008. Before that, Mr. Modig served as Chief Financial Officer at Surplex AG from 2001 to 2003 and as Finance Director Europe of U.S.-based Hayward Industrial Products Inc. from 1999 to 2001. In previous positions, Mr. Modig was a Partner in the Brussels-based private equity firm Agra Industria from 1994 to 1999 and a Senior Manager in the Financial Services Industry Group of Price Waterhouse LLP in New York from 1991 to 1994. Mr. Modig was also a director of Mobile Loyalty plc from 2012 to 2013. He is currently a member of the Supervisory Board and audit committee chair of Centogene N.V. Mr. Modig received a bachelor’s degree in business administration, economics, and German from the University of Lund, Sweden, and an M.B.A. from INSEAD, Fontainebleau, France.
Senthil Sundaram
Mr. Sundaram has served as a member of the Sio board since June 2019. He was most recently the Chief Financial Officer at Nightstar Therapeutics, until its acquisition by Biogen in June 2019. While at Nightstar, he was responsible for corporate finance and operations, business development, and strategy. He helped lead the execution of multiple equity offerings, as well as licensing and M&A transactions. Prior to joining Nightstar, Mr. Sundaram was the Vice President and Head of Business and Corporate Development at Intercept Pharmaceuticals, Inc. Previously, Mr. Sundaram spent 13 years in the healthcare investment banking groups at Lehman Brothers/Barclays, Citigroup and Lazard. Mr. Sundaram holds a BS in Computer Engineering and a BA in Economics from Brown University.
Scientific Advisors

Guangping Gao, PhD
Guangping Gao, PhD
Chief AAV Scientific Advisor
Dr. Gao is Co-Director of the Li Weibo Institute for Rare Disease Research, Director of the Horae Gene Therapy Center and Viral Vector Core, Professor of Microbiology and Physiological Systems and Penelope Booth Rockwell Professor in Biomedical Research at the University of Massachusetts Medical School. Dr Gao’s more than 30 years in scientific research in molecular genetics have made foundational contributions to the development of viral vector gene therapy for rare genetic diseases including the discovery, development and engineering of novel viral vectors for in vivo gene delivery as well as preclinical and clinical gene therapy product development. He has also made significant contributions to the development of viral vector manufacturing for gene therapy applications and the development of technology platforms for novel gene therapy approaches in humans. Dr. Gao has published nearly 300 research papers and serves as the Executive Editor-In-Chief of Human Gene Therapy, Senior Editor of the Gene and Cell Therapy book series and serves on the Editorial Boards of several other gene therapy and virology journals. In addition to previously serving as President of ASGCT, he is an elected fellow of the U.S. National Academy of Inventors, holding 174 patents and an additional 373 patent applications pending with over 10 licensed to pharmaceutical companies. Dr. Gao is co-founder of Voyager Therapeutics, Adrenas Therapeutics and Aspa Therapeutics.
Partners
Sio Gene Therapies believes that patients deserve long-lasting, transformative therapies, not just incremental improvements. We see the potential in harnessing the power of gene therapies to deliver better options for patients and believe that collaborations with other leaders in the field will get us there faster. We look for partners who share our same vision and are driven by the same urgency to deliver new gene therapies to patients. If you are interested in working with us, please contact us at info@siogtx.com.
Sio is proud to partner with the following organizations to accelerate the development of our transformative gene therapies: