Management Team

David J. Leffell, MD

Chief Medical Advisor

David J. Leffell, MD, a physician, researcher and writer is the David Paige Smith Professor of Dermatology and Surgery and chief of dermatologic surgery and cutaneous oncology at the Yale School of Medicine. For 15 years he was chief executive officer of the Yale Medical Group, one of the country’s largest academic medical group practices, providing specialty care in more than 120 medical areas. For almost a decade Dr. Leffell was also deputy dean for clinical affairs at Yale University School of Medicine responsible for relations with Yale New Haven Hospital, strategic development and clinical trials oversight.

Dr. Leffell serves as chair of the Advisory Board of Tullis Heath Investors where he is also a venture partner. Previously he was an advisory partner at MalinPLC. Dr. Leffell consults with a wide range of consumer and skin focused companies including Merck and Unilever, as well as early stage biotechnology and pharmaceutical companies. He serves on the advisory boards of Dermasensor, First String and on the board of Validus Pharmaceuticals.

Dr. Leffell’s clinical focus is the diagnosis, treatment, and prevention of melanoma and nonmelanoma skin cancer and new diagnostic and therapeutic technologies in skin health.

He holds a patent for a laser device to measure skin aging and shares a patent for the discovery of the skin cancer gene, PTCH. He also invented a novel surgical therapy for treating vitiligo, a depigmenting condition of the skin.

Dr. Leffell is the author or co-author of more than 160 papers, several. He was an editor of the world’s leading textbook of dermatology, Fitzpatrick’s Dermatology in General Medicine (including Russian and Spanish editions) and author of Manual of Skin Surgery (English and Chinese editions). Dr. Leffell wrote a consumer oriented book, Total Skin: The Definitive Guide to Whole Skin Care for Life, published by Hyperion. It is considered the go-to reference for information about skin health. Dr. Leffell has held editorial positions with many peer-reviewed journals and is also the author of a contribution called “Longevity Strategies” which appears in The Enlightened Bracketologist: The Final Four of Everything, published in 2006.

Dr. Leffell, born and raised in Montreal received his BS, cum laude from Yale College. He graduated with MD, CM from McGill University Faculty of Medicine in Montreal. Board certified in medicine and dermatology, he completed residencies at Cornell Cooperating Hospitals (Memorial Sloan Kettering Cancer Center and North Shore Hospital) and Yale-New Haven Hospital. At Yale, he also completed a post-doctoral fellowship as a National Institutes of Health research fellow. Following his residencies, he completed a clinical fellowship in advanced dermatologic surgery at the University of Michigan before returning to Yale in 1988 to found a new program in skin cancer and melanoma. The program, which combines patient-centered clinical care with teaching and research, has trained over 140 residents and 24 fellows in advanced dermatologic surgery and skin oncology.

Dr. Leffell lives in New Haven and Norfolk, CT. He has served as president of Artspace in New Haven and Connecticut Public Television. He has been a trustee of the Hopkins School, New Haven since 2011.


Christina Grek, PhD
Senior Director of Research and Development

Dr. Grek is an experienced translational scientist with foundations in both industry and academia. After receiving her BScH at Queen’s University in Kingston, Ontario, Canada, Dr. Grek pursued a career in industry at the biotech startup KAIROS Scientific, where she aided in the development of a high-throughput technology, that enables solid phase enzyme screening of mutagenized bacterial libraries expressing enzymes that have undergone directed evolution.  She then worked as a cancer researcher in the drug discovery team at SUGEN, a pioneering drug discovery company focused on the development of small-molecule protein kinase inhibitors as cancer therapeutics. At SUGEN, Dr. Grek developed a keen understanding of the pipeline components involved in drug discovery protocols and the development of successful therapeutics.

Dr. Grek earned a PhD in Biomedical Sciences at the Medical University of South Carolina, Charleston, SC, where she studied the role of oxygen sensitive genes in the alveolar epithelium and successfully designed and developed a novel semi-permeable hollow fiber based membrane system that enables the culture and differentiation of alveolar epithelial cells. At MUSC, she continued her pursuit as a translational scientist through a series of preclinical and clinical studies focusing on the discovery and development of pharmacodynamic biomarkers for current and novel redox modulating chemotherapeutics. Dr. Grek was also instrumental in a drug discovery program involving the screening, development, and evaluation of small molecule inhibitors that target protein disulfide isomerase that may serve as the basis for future cancer therapeutic development.   She has extensive experience in the development of in vivo and in vitro model systems as well as experience in the development and implementation of preclinical and clinical studies.

Carissa James

Carissa James, PhD
Director of Research and Development

Dr. James is a translational scientist committed to discovering novel therapeutic opportunities and translating basic research into clinical successes in the field of intercellular junctions. She earned a PhD in Translational Biology, Medicine, and Health program at the Fralin Biomedical Research Institute at Virginia Tech, where she investigated the role of GJA1-20k, an alternatively translated isoform of Connexin43 encompassing the C-terminus, in cancer progression. Dr. James identified translation of GJA1, the mRNA coding for Cx43 and GJA1-20k, as a target for TGF-b, and a novel mechanism by which intercellular junctions are degraded during epithelial-mesenchymal transition (EMT). EMT is fundamental to wound healing in epithelial cells, development, and cancer metastasis. This discovery and her interest in translational biology led her to FirstString Research, where she is focused on the development of therapeutics that capitalize on the translational potential of the Cx43 C-terminus. Dr. James is an expert on the junctional and non-junctional roles of the Cx43 C-terminus and the mechanisms by which aCT1 peptide modulates the behavior of junctional proteins.