Clinical Sciences


Clinical Sciences by CenExel offers a unique opportunity for collaboration with pharmaceutical sponsors, CROs, and vendors, to support study development and conduct within the Sponsor’s clinical development program across the development lifecycle. These activities include Clinical Sciences support from pre-IND, Phase I, and translational medicine studies through to Phase III pivotal studies, peri-approval, and Phase IV studies. Clinical Sciences can provide scientific consulting for clinical development planning, study design, recruitment solutions, dose selection criteria to support more confident go/no-go decisions through the application of fit-for-purpose biomarkers, measures, and endpoints.


Clinical Sciences Leadership

Debra Hoffmeyer

Larry Ereshefsky, PharmD, BCPP

Chief Scientific Officer, Early Phase

Dr. Ereshefsky is an internationally recognized key opinion leader in clinical translational central nervous system research with a proven track record in designing and performing first-in-human, proof-of-concept, and a broad range of Phase I clinical pharmacology studies. With over 30 years’ experience leading early phase research sites, he is utilized as a global resource within CenExel, providing support to ensure consistency and quality across sites. Dr. Ereshefsky is actively involved in strategic planning for compound development. He helps design translational research programs and define the critical path towards regulatory approval. He has extensive experience working with regulatory agencies and developing strategic plans to address compound differentiation and reimbursement challenges.

Dr. Ereshefsky has contributed significantly to many drug approvals, including by providing drug development planning, PK evaluation, and methodological innovation. He has introduced strategies to de-risk early phase drug development through the application of neurocircuitry/biomarker-based (RDoC) strategies, e.g., continuous CSF sampling, QEEG, ERPs, PSG, fMRI, PET, and cognitive and behavioral paradigms.

Dr. Ereshefsky is a retired Regents Professor of Pharmacy, Psychiatry, and Pharmacology from The University of Texas at Austin and University of Texas Health Science Center at San Antonio. Subsequently, he was EVP and CSO for California Clinical Trials from 2003 to 2008 when it was acquired by Parexel International where his role was VP, Principal Pharmacologist, and Therapeutic Area Leader for CNS Early Phase until his departure in 2016. Dr. Ereshefsky has published almost 150 peer-reviewed scholarly articles and abstracts. He received his Pharm.D. from the University of Southern California. His post Post-Graduate Residency in Psychiatric Pharmacy/Psychopharmacology was completed at Los Angeles County+USC Medical Center (LAC+USC).

Dr. Robert Litman

Robert E. Litman, MD

Chief Scientific Officer, Psychiatry

Dr. Litman is the Medical Director and Principal Investigator for all clinical trials at CenExel CBH. He developed his interest in the treatment of schizophrenia at Massachusetts General Hospital, where he completed his residency in psychiatry. Shortly thereafter, he joined the Experimental Therapeutics Branch, National Institute of Mental Health, NIH, as a Senior Staff Fellow. He remained at NIH until 1995, where he continued to pursue his interest in schizophrenia, including investigating the effects of atypical neuroleptics biological and genetic markers in schizophrenia, as well as the development of better combination therapies for schizophrenia using the alpha-2 antagonist idazoxan. After leaving the NIH, he formed his own clinical trials research organization, first in conjunction with area hospitals, and then as a free-standing inpatient and outpatient clinical research organization now known as CBH Health. Since then, he has conducted over 300 Phase I-IV clinical trials and has participated in many of the important advances in pharmacotherapy of schizophrenia and other brain disorders.

Dr. Litman has an extensive background in psychopharmacology, the evaluation and treatment of schizophrenia, bipolar, major depression, anxiety, and Alzheimer disease. He serves as a consultant in psychopharmacology to many area hospitals and group practices, has over 30 academic publications, and frequently speaks about new advances in the field of psychopharmacology, and on the current issues regarding drug development for psychiatric illness. He is currently an Associate Professor of Psychiatry at Georgetown University Medical School (where he teaches and trains Psychiatry residents) and a Fellow and Diplomate of the American Board of Psychiatry and Neurology and Diplomate, Added Qualifications in Geriatric Psychiatry.

Dr. Robert Litman

Diana Shuster, PhD

Vice President of Clinical Sciences

Dr. Diana Shuster, PhD, serves as Vice President of Clinical Sciences at CenExel, bringing over a decade of expertise in Translational and Early Phase central nervous system research. Her role encompasses the design and execution of first-in-human, proof-of-concept, and diverse Phase I clinical pharmacology studies. With a background spanning big pharma, CROs, and TechBio, Dr. Shuster has significantly contributed to advancing rare disease compounds.

In her capacity as Vice President, Dr. Shuster is dedicated to integrating her multifaceted expertise to ensure consistency and quality across global research sites. Actively engaged in strategic planning, she specializes in designing translational research programs and navigating the critical path to regulatory approval. Driven by a commitment to de-risking early phase drug development, she employs innovative strategies, including continuous CSF sampling, QEEG, ERPs, PSG, fMRI, PET, and cognitive paradigms.

Internal Scientific Experts

Todd Bertoch, MD

Todd Bertoch, MD

Chief Medical Officer, CenExel JBR

Dr. Todd Bertoch, M.D. is a diplomate of the American Board of Anesthesiology. He graduated Summa Cum Laude with a Bachelor of Science Degree in Biochemistry from California State University at Fullerton and received a Doctor of Medicine degree from the Uniformed Services University of the Health Sciences in Bethesda, Maryland. After an internship in Internal Medicine, he completed his Anesthesiology residency at Wilford Hall Medical Center in San Antonio, Texas, where he was Chief Resident and received the Arthur B. Tarrow Outstanding Resident Award. He is a member of the esteemed Alpha Omega Alpha Honor Medical Society.

Dr. Bertoch served as an anesthesiologist in the United States Air Force until 2006 where he gained extensive experience in both trauma care and pain management. He is a recipient of the Air Force Achievement Medal, the Air Force Commendation Medal, and the Meritorious Service Medal.

After completing his military service, Dr. Bertoch served for 11 years as the managing partner of Prescott Anesthesia in Prescott, Arizona where his practice included a focus on cardiovascular surgery, chronic pain management and addiction medicine. Since joining JBR Clinical research in 2017, he has served as Principal Investigator for over 100 clinical trials, defended development programs for sponsors before the FDA, been invited to present study results on behalf of clients at professional meetings, designed and authored numerous clinical trial protocols, and has helped author several industry-related articles and white papers.

Rajeev Kumar, MD

Chief Medical Officer, CenExel RMCR

Dr. Kumar is one of the world’s foremost experts on movement disorders, with unparalleled experience and expertise treating and researching Parkinson’s disease, Huntington’s disease, Dystonia, and many other debilitating movement disorders. Trained at the renowned Mayo Clinic, Dr. Kumar has over two decades of experience working in the fields of Neurology and Movement Disorders, and as Medical Director of Rocky Mountain Movement Disorders Center and director of the Huntington’s Disease Center of Excellence both here and at the former Colorado Neurological Institute, he has solidified his status as one of the most trusted and respected professionals in the field.

Dr. Kumar has been dedicated to the care of patients with movement disorders in Colorado since 1998. He has been designated a Dystonia Doctor of Excellence by the Dystonia Medical Research Foundation. Dr. Kumar and his team serve individuals with movement disorders from early adulthood through advanced age. Our center is dedicated to helping patients with serious neurologic conditions achieve their life goals.

Robert A. Riesenberg, MD

Medical Director, CenExel ACMR

Dr. Riesenberg is the founder and principal investigator for CenExel ACMR. A research psychiatrist with four decades of experience, Dr. Riesenberg’s primary focus is on CNS, PK, healthy normal, and child/adolescent disorders. Dr. Riesenberg has been the principal investigator in over 600 studies.

Dr. Riesenberg earned a bachelor’s degree in both Zoology and Psychology from Memphis State University in 1972. In 1975, he earned his MD from the University of Tennessee. He is licensed to practice in Georgia.

Sanjiv K. Sharma, MD, CPI

Chief Medical Officer, CenExel AMRI

Dr. Sharma has been involved in memory research since 2009. In 2013, he started AMRI as the principal investigator. Since then he has worked on over 35 memory related protocols. Dr. Sharma has his board certification in internal medicine as well as geriatric medicine. He is passionate about caring for patients and families who are worried about memory loss.

Dr. Sharma graduated from Mahatma Gandhi Medical Memorial College in Jamshedpur, India and completed his residency in internal medicine at Jersey Shore University Medical Center. In 2000, Dr. Sharma opened his private practice, Geriatric Medical Center, in Toms River, New Jersey.

Contact us if you’re interested in learning more about our Clinical Sciences services.