Our Mission

Transform patient outcomes by bringing the cellular biology of depression into its diagnosis and treatment

Our Diagnostic Blood Test:

Commercialization of a patented biomarker-based blood test to assist physician diagnosis and treatment efficacy for each patient diagnosed and in treatment for depression. A variant of this is in development for a prospective predictive screen using a patient's leukocytes to guide treatment options, including drug combinations.


MoodMarkDx® and MoodMarkRx® will be the first evidence-based tests to provide unbiased, biological evidence of depression diagnosis and treatment-response prediction derived from physiological changes specific to clinical depression. U.S. and international patents protect Pax's biomarker assays for antidepressant drug development and Pax's blood tests.

Our Drug Development Services Business:

We are offering pharmaceutical and biotechnology companies the opportunity to work with Pax to analyze antidepressant compounds in early stage discovery and antidepressant clinical trials. In clinical trials, the blood test can streamline recruitment by identifying potential subjects who are and are not biologically depressed, identify responders and non-responders, provide quantitative data, produce greater efficiencies in development, lower costs, and develop better drugs. Preclinical neurobiology and central nervous system (CNS) drug discovery solutions allow the company to work with pharmaceutical companies to identify and validate targets, select new compounds, and reposition or repurpose shelved compounds.


Revenues generated from drug development services are intended to bootstrap the continued development of the blood test assay for the consumer and pharmaceutical markets, and to explore novel pathways for antidepressant development.


Management Team

Mark M. Rasenick, PhD
Founding Member
Mark M. Rasenick, PhD
President & Chief Scientific Officer

Distinguished professor of physiology and psychiatry, specializing in the biology of mood disorders, and long-time advisor to policymakers on mental health.

Helene J. Shambelan, JD-pax neuroscience-sm-brd
Helene J. Shambelan, JD
Chief Executive Officer

Former law professor focused on corporation and securities law, concentrating for over a decade on the areas of health and biotechnology.

SteveTargum_Chief Medical Advisor
Steven D. Targum, MD
Chief Medical Officer

Former professor and chair of psychiatry with three decade expertise in clinical trial methodology and drug development strategy.

Scientific Advisory Board

Mark M. Rasenick, PhD
Founding Member

Mark M. Rasenick, PhD
Founding Member

Dr. Rasenick's work has focused on G protein signaling in the nervous system and the relationship of neurotransmitter activation to rapid modification of the cytoskeleton. He has been particularly interested in how G proteins and the cytoskeleton work in concert to modify synaptic shape and to form a molecular basis for depression and the action of antidepressant drugs. The most recent work from his group is the basis for a blood test indicating depression and therapeutic response to antidepressant therapy.
The science in Dr. Rasenick’s lab has been funded, continuously since 1984, by the NIMH. He has also been funded by other federal agencies (NIDA, NIA, NIAD, NSF, DOD) and by industry sources. He is principal investigator of an NIMH training grant, “Training in the Neuroscience of Mental Health”, which supports graduate students and postdoctoral fellows in the neurosciences. He serves on many scientific review panels (NIH, NSF, DOD), and editorial boards and is the author of numerous publications. Dr. Rasenick has received honors both for teaching and research, including the Searle Young Faculty Award from the Chicago Community Trust, the University Scholar Award and Distinguished Faculty Award from the University of Illinois, a Research Scientist Award from the NIMH, and a Robert Wood Johnson Health Policy Fellowship from the Institute of Medicine/National Academy of Sciences. He is an elected fellow of the American College of Neuropsychopharmacology and the American Association for the Advancement of Science. In addition to research and teaching, Dr. Rasenick is active in public policy. He served as a member of the Commission on Social Action of Reform Judaism and the Chapters committee and Government and Public Affairs Committee (co-chair) and International Affairs Committee of the Society for Neuroscience. He serves on the Public Affairs committees of the American Society for Biochemistry and Molecular Biology, the Society for Neuroscience and the American College of Neuropsychopharmacology. He is a member of the Basic and Clinical Neuroscience Links Committee for the International Brain Research Organization (IBRO). While a Robert Wood Johnson Fellow (1999-2000), he was a staff member of the Senate Committee on Health, Education, Labor, and Pensions with Senator Edward M. Kennedy, (D Mass.). During this time, he worked on legislation concerning Cancer screening, Medicare Prescription Drugs, Organ Transplantation Policy and Mental Health Policy. He is also involved in international outreach for neuroscience and has organized programs designed to foster international cooperation in the basic and clinical neurosciences in Vietnam, Cuba and throughout Latin America. He was asked to testify before the Senate Committee on Foreign Relations concerning outreach to Cuban biomedical scientists. In 2009, he was appointed an Ambassador for Global Health Research by the Paul Rogers Society.

Paul Billings, MD, PhD
Founding Member

Dr. Billings was Senior Vice President for Corporate Development at Laboratory Corporation of America Holdings (LabCorp). He recently served as Director and Chief Scientific Officer of the Genomic Medicine Institute at El Camino Hospital, the largest community hospital in Silicon Valley, improving patient care through expanding the use of medically relevant genomic technologies in clinical settings. He currently serves as a member of the United States Department of Health and Human Services Secretary's Advisory Committee on Genetics, Health and Society, where he helps shape policy in the rapidly evolving field of genomic medicine.
Dr. Billings has had a distinguished career as a physician and researcher. He has been a founder or chief executive officer of companies involved in genetic and diagnostic medicine, including GeneSage, Omicia and CELLective Dx Corporation. He has held academic appointments at some of the most prestigious universities in the United States, including Harvard Medical School, Stanford School of Medicine and the University of California, Berkeley, and has served as a physician at a number of medical centers throughout the country, including the University of California, San Francisco. He is the author of nearly 200 publications and books on genomic medicine. Dr. Billings holds an M.D. from Harvard Medical School and a Ph.D. in immunology, also from Harvard University.
Eric Nestler

Eric Nestler, MD, PhD

Dr. Nestler is the Nash Family Professor of Neuroscience and the Dean of Academic and Scientific Affairs at Mt. Sinai. Eric was previously the Lou and Ellen McGinley Distinguished Professor and Chair of Psychiatry at the University of Texas Southwestern Medical Center at Dallas. He was formerly the Elizabeth Mears and House Jameson Professor of Psychiatry and Director of the Division of Molecular Psychiatry at Yale University School of Medicine.
The focus of his research is molecular mechanisms underlying behavior disorders. Dr. Nestler is a member of the Institute of Medicine of the National Academy of the Sciences.
Mark Rapaport, M.D-pax-neuroscience

Mark Rapaport, MD

Dr. Rapaport is CEO of Huntsman Mental Health Institute (HMHI) and chair of the Department of Psychiatry at the University of Utah School of Medicine. A nationally recognized clinician and researcher known for his interdisciplinary approach to mental health treatment and care, he recently served as the Reunette W. Harris Professor and Chair of the Department of Psychiatry and Behavioral Sciences at the Emory University School of Medicine in Atlanta.
He also served as chief of Psychiatric Services for Emory Healthcare Systems. During his tenure, he co-created the Emory Brain Health Center, breaking down silos between psychiatry, neurology, neurosurgery, and neuroscience, allowing a collaborative approach to studying and solving the challenges of brain disorders. While at Emory, he also co-created the Addiction Alliance of Georgia with the Hazelden Betty Ford Foundation, transforming how addiction and recovery services are delivered in Georgia. Before joining Emory University, he was the Chair of Psychiatry and Behavioral Neurosciences at Cedars-Sinai Medical Center and professor of Psychiatry at both Cedars-Sinai and the David Geffen School of Medicine at University of California, Los Angeles. Nationally known for his leadership, writing, and research, Rapaport has received several awards and honors for his work. Most recently, he was recognized as a Distinguished Life Fellow from the American Psychiatric Association (APA). He is currently editor-in-chief of Focus: A Journal of Lifelong Learning in Psychiatry published by the APA. As an investigator, Rapaport has been funded by the National Institute of Mental Health (NIMH) for three decades and has over 180 peer-reviewed publications. His research interests include the biologic genesis of anxiety disorders, bipolar disorder, depression, and immunity abnormalities in psychotic and mood disorders. Rapaport graduated cum laude in biology from the University of California, San Diego, where he also earned his medical degree and completed his residency in psychiatry.
Dr. Natalie Rasgon-pax-neuroscience

Natalie Rasgon, MD, PhD

Dr. Rasgon is a Professor in the Department of Psychiatry and Behavioral Sciences and Obstetrics and Gynecology in the Stanford School of Medicine. Dr. Rasgon has been involved in longitudinal placebo-controlled neuroendocrine studies for over two decades, and she has been involved in neuroendocrine and brain imaging studies of estrogen effects on depressed menopausal women for over 10 years.
In addition to her duties as a Professor of Psychiatry and Obstetrics & Gynecology, Dr. Rasgon is also the Director of the Stanford Center for Neuroscience in Women’s Health and Associate Dean of Academic Affairs for the School of Medicine. She has an extensive history of teaching and mentoring, and many of her trainees have secured independent faculty positions in academia.
Alan F. Schatzberg, M.D. -pax neuroscience

Alan F. Schatzberg, MD

Dr. Schatzberg is the Kenneth T. Norris, Jr. Professor and Chairman of the Department of Psychiatry and Behavioral Sciences at Stanford Dr. Schatzberg is an active investigator in the biology and psychopharmacology of anxiety and depressive disorders. He has authored or edited over 200 publications, including the Manual of Clinical Psychopharmacology and the recently published Textbook of Psychopharmacology.
Dr. Schatzberg has recently investigated antecedents of depression in adults. Dr. Schatzberg is a member of the Institute of Medicine of the National Academy of the Sciences and is the current past-president of the American Psychiatric Association.

Steven Targum, MD

Dr. Targum is the Chief Medical Officer for Pax Neuroscience. He has been principal investigator for over 100 clinical trials over the past three decades. After teaching Psychiatry at Georgetown University School of Medicine and University of South Florida School of Medicine, and serving as Medical Director at Sarasota Palms Hospital, Dr. Targum was Chair of Psychiatry at Hahnemann Medical School.
He has continued his research, focused primarily on the experimental design of CNS clinical trials, subject selection, ratings precision, management of placebo response, in-study monitoring, and optimization of clinical trial outcomes, in numerous Chief Medical Officer and Advisor roles.
Dr. Madhukar Trivedi

Madhukar Trivedi, MD

Dr. Trivedi is a Professor of Psychiatry, Chief of the Division of Mood Disorders, and founding Director of the Center for Depression Research and Clinical Care at UT Southwestern Medical Center, where he holds the Betty Ho Hay Distinguished Chair in Mental Health and the Julie K. Hersh Chair for Depression Research and Clinical Care.
An internationally recognized translational researcher focusing on developing and validating biosignatures of depression, he has served as PI and Co-PI on several single and multi-site clinical trials, funded by NIH, foundations and industry members. Dr. Trivedi has authored more than 500 peer-reviewed articles and chapters about the diagnosis and treatment of mood disorders. For six consecutive years, he has been named a Global Highly Cited Researcher by Clarivate Analytics. His accolades include the Gerald L. Klerman award from the National Depressive and Manic-Depressive Association Scientific Advisory Board, the Psychiatric Excellence Award from the Texas Society of Psychiatric Physicians, the Gerald Klerman Senior Investigator Award, the American Psychiatric Association Award for Research, and the American College of Psychiatrists Award for Research in Mood Disorders. Dr. Trivedi served as Deputy Editor of the American Journal of Psychiatry and as President of the American Society of Clinical Psychopharmacology.
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