Senior Management Team


David M. Epstein, Ph.D. – Co-Founder, President and Chief Executive Officer

David M. Epstein, Ph.D., is a biopharmaceutical leader and executive who has successfully led large and small R&D teams in academic, start-up, mid-size, and global large-pharmaceutical settings. His teams have progressed multiple novel agents through development in oncology, cardiovascular disease, and retinal degeneration.

Before his appointment as Black Diamond’s President and CEO, David was Vice Dean, Innovation & Entrepreneurship, and Associate Professor in Cancer & Stem Cell Biology, at Duke-NUS Medical School, Singapore, where he founded and built Duke-NUS’s Centre for Technology & Development, which  has developed a pipeline of innovation projects. Previously, he was Chief Scientific Officer at OSI Pharmaceuticals, a pharmaceutical company acquired by Astellas Pharma, and founder of Archemix Corporation, where he led the advancement of multiple product candidates into the clinical in multiple therapeutic areas.

David earned a Ph.D. in Biochemistry at Brandeis University and completed a joint post-doctoral fellowship, leading a collaboration in protein structure, function, and NMR dynamics between the labs of Steven Benkovic (Penn State) and Peter Wright at The Scripps Research Institute in La Jolla, California. He received a B.Sc. in Chemistry from Lewis & Clark College.

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Elizabeth Buck, Ph.D. - Co-Founder, Executive Vice President, Discovery & Translational Sciences

Elizabeth Buck, Ph.D., was instrumental in developing Black Diamond’s MAP platform through which she made critical discoveries leading to our understanding of the properties of allosteric mutations in oncogene activation.

She has more than 15 years of experience in oncology therapeutics in biotechnology and large pharmaceutical companies. Her expertise and productivity are evidenced by more than 40 peer-reviewed publications and patents. Prior to co-founding Black Diamond and being named its Executive Vice President, Discovery and Translational Sciences, Liz was Assistant Director of Advanced Preclinical Pharmacology at OSI Pharmaceuticals, where she led discovery and translational research to advance a series of oncology programs to clinical development. During her tenure at OSI, she managed multidisciplinary global teams and spearheaded major academic collaborations to progress programs to investigational new drug applications.

Liz earned a Ph.D. in Cellular and Molecular Biology from New York University/Mount Sinai School of Medicine and completed postdoctoral work with Jim Wells at Sunesis Pharmaceuticals. She received her undergraduate degree in Physics from the University of New Hampshire.

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Brent Hatzis-Schoch - Chief Operating Officer, General Counsel

With more than 20 years’ experience in the global pharmaceutical and biotechnology industry, Brent Hatzis-Schoch has held leadership positions at both commercial and development-stage companies.

Prior to joining Black Diamond as Chief Operating Officer, General Counsel, Brent was Senior Vice President (SVP), General Counsel and Corporate Secretary at Radius Health, Inc., a publicly traded commercial-stage biopharmaceutical company focused on the areas of osteoporosis and oncology. While at Radius, Brent had responsibility for the legal, intellectual property, contracts management, compliance, regulatory, and quality assurance functions, and helped build the company from a development-stage company to a commercial organization. Previously, he served as SVP and Chief Legal Counsel at Merz Pharma, an international healthcare company, in Frankfurt, Germany, where he had global responsibility for the legal, IP, and compliance functions. Brent began his legal career in private practice and later held senior legal positions in the U.S. and internationally, including as General Counsel to two publicly traded development-stage German biopharmaceutical companies, European legal counsel for Baxter International, and Associate General Counsel of Pharmacia Corporation.

Brent holds a Juris Doctor from George Washington University and was a Fulbright Scholar at the University of Cologne, Germany. He received his B.A. in International Relations from the University of Delaware.


Christopher Roberts, Ph.D. – Chief Scientific Officer

As Black Diamond’s Chief Scientific Officer, Chris Roberts, Ph.D., brings more than two decades of experience leading discovery and development functions and clinical development projects for multiple therapies in oncology and immunology, among other areas. He joined Black Diamond from SR One, the corporate venture capital arm of GlaxoSmithKline (GSK), where he was an Entrepreneur in Residence.

Previously, Chris was the Vice President (VP) of Chemistry and Early Development at Syros Pharmaceuticals, Inc., a publicly traded biotechnology company focused on gene control and drugging transcription, where he built and led a variety of discovery and development functions and helped guide two oncology assets into clinical development. Prior to joining Syros, Chris held numerous positions of increasing responsibility at GSK, including VP and Head of the Host Defense Discovery Performance Unit, and also led multiple clinical development projects. He joined GSK as Senior Director of Hepatitis C Virus (HCV) Medicinal Chemistry via its acquisition of Genelabs Technologies. As a medicinal chemist at Genelabs, Chris was significantly involved in establishing Genelabs’ HCV research focus. His work has been extensively published.

Chris earned a Ph.D. in Organic Chemistry from the University of California, Riverside, and completed a post-doctoral fellowship at the University of Bern, Switzerland. He graduated with a B.A. in Chemistry from Whitworth University.

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Rachel Humphrey, M.D. – Chief Medical Officer

Rachel Humphrey has more than 20 years of oncology drug development experience and has pioneered the clinical development of numerous first-in-class oncology drugs. As Black Diamond’s Chief Medical Officer, Rachel is responsible for leading and executing the Company’s clinical development strategy.

Rachel joined Black Diamond from CytomX Therapeutics, Inc. in 2020, where she served as Chief Medical Officer and as a member of its Board of Directors. While at CytomX, she supervised the clinical development of ProbodyTM Therapeutics for the treatment of cancer. Previously, she held numerous senior leadership roles in cancer drug development, including Vice President (VP), Head of Immuno-Oncology at Eli Lilly and Company, Senior VP and Head of Immuno-Oncology at AstraZeneca, Executive VP and Chief Medical Officer at Mirati Therapeutics, and VP, Clinical Development at Bristol-Myers Squibb (BMS). Rachel also held multiple positions in global clinical development at Bayer. Rachel’s career is notable for, among other achievements, her overall supervision of the early and late-stage clinical development of ipilimumab (Yervoy®) at BMS and sorafenib (Nexavar®) at Bayer.

Rachel received her M.D. from Case Western Reserve University and her B.A. from Harvard University. She received her training in internal medicine at The Johns Hopkins Hospital and started her career as an oncology fellow and staff physician at the National Cancer Institute in Bethesda, MD. She is also the lead singer and one of the co-founders of the band, The Checkpoints, a blues band made up of luminaries in immuno-oncology, including the Nobel Laureate, Jim Allison, and is featured in the movie “Jim Allison: Breakthrough,” which was released in the fall of 2019.

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Thomas (Tommy) Leggett – Chief Financial Officer

Tommy Leggett brings nearly two decades of multi-disciplinary experience leading, obtaining financing for, and advising life science companies. As Black Diamond’s Chief Financial Officer (CFO), Tommy oversees all of the Company’s financial operations including financial strategy, investor relations, accounting operations, financial planning and analysis, tax and treasury.

He joined Black Diamond from Axcella Health, where Tommy was Senior Vice President of Finance and CFO. During his tenure at Axcella, Tommy was influential in three of Axcella’s financings, including its initial public offering in May 2019.  Before joining Axcella, Tommy was Treasurer and Head of Business Development Finance at Purdue Pharma, L.P. Previously, he was an investment banker for the healthcare groups at J.P. Morgan Securities, Lazard Frères & Company, and UBS Securities, respectively.

Tommy holds an M.B.A. in Finance from The Wharton School at the University of Pennsylvania and a B.A. in Economics from Columbia University.

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Fang Ni, Pharm.D., Chief Business Officer

Fang Ni, Pharm.D, brings considerable experience in business development and corporate strategy in the life sciences sector. As Chief Business Officer, Fang is responsible for leading Black Diamond’s strategic and business development initiatives.

Prior to joining Black Diamond in 2020, Fang served as Principal and member of the investment team at Versant Ventures. He was Black Diamond’s founding Chief Business Officer following the Company’s Versant-led Series A financing, making critical contributions to Black Diamond’s corporate and business strategy. While at Versant, Fang also served as Interim Chief Business Officer for several new ventures, including Monte Rosa Therapeutics and Bright Peak Therapeutics. Prior to joining Versant, he was previously a Global Business Development & Licensing director within Roche’s Partnering organization, where he was responsible for leading transactions across the fields of oncology, immunology, and infectious and rare diseases.

Fang earned a Doctor of Pharmacy degree from Purdue University, and he then completed a post-doctoral fellowship at Rutgers University.

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Karsten Witt, M.D., Senior Vice President of Clinical Development

Karsten Witt, M.D., brings more than 30 years of clinical development and regulatory affairs experience in the areas of oncology and inflammatory disease. Prior to joining Black Diamond, Karsten served as Vice President, Clinical Sciences & Drug Safety at Array BioPharma, and as Senior Vice President, Pharmaceutical Operations at OSI Pharmaceuticals, where he was involved in the development of small-molecule targeted oncology therapies. He has served on executive management and global development committees, and as a chair of scientific committee for TopoTarget, a Copenhagen-based biotechnology company, until its merger with BioAlliance, which resulted in the formation of Onxeo.

Karsten earned his M.D. from the University of Copenhagen and practiced medicine at Hvidovre University Hospital in Copenhagen in the internal medicine subspecialties of gastroenterology, infectious disease, and cardiology, before transitioning to the biopharmaceutical industry.