The 2025 R.T. Williams Distinguished Scientific Achievement Award Presentation

Includes a Live Web Event on 03/20/2026 at 12:00 PM (EDT)

The International Society for the Study of Xenobiotics (ISSX) is proud to announce that Dr. Scott Obach has been named the 2025 recipient of the R.T. Williams Distinguished Scientific Achievement Award, one of the most prestigious recognitions within the Society. This award, generously sponsored by Charles Crespi and his family, honors ISSX members who have made substantial and lasting contributions to the field of xenobiotic research.

As part of this distinguished recognition, Dr. Obach delivered his award lecture at the 2025 ISSX International Meeting in Chicago. This webinar offers the broader ISSX community the opportunity to hear his presentation, highlighting the scientific achievements and insights that have shaped his career and contributed meaningfully to the advancement of xenobiotic research worldwide.

About the R.T. Williams Distinguished Scientific Achievement Award Named in honor of R.T. Williams, this award recognizes an ISSX member who has made seminal and sustained scientific contributions to the field. It represents the pinnacle of scientific recognition within ISSX and celebrates vision, dedication, and achievement at the highest international level.

R. Scott Obach, PhD

Vice President of Scientific Research

Pfizer

Dr. Obach’s distinguished career at Pfizer Global Research and Development exemplifies the award’s spirit. Rising from Research Scientist to Vice President of Scientific Research, he has advanced global understanding of drug metabolism, enzyme kinetics, bioactivation, and drug-drug interactions. His work has profoundly influenced drug discovery and development, improving the prediction of human pharmacokinetics across therapeutic areas.

A prolific scientist, Dr. Obach has authored more than 240 publications, achieved an H-Index of 76, and garnered over 12,000 citations. His groundbreaking research and mentorship have earned him a global reputation as the “godfather of applied ADME sciences.

Dr. Obach’s contributions extend beyond research. A committed leader within ISSX, he has served as President (2022–2023), President-Elect (2020–2021), and Chairman of the Scientific Advisory Board (2016–2020), as well as a journal editor for Drug Metabolism and Disposition and Xenobiotica.

This year’s award marks a historic milestone, as Dr. Obach becomes the first industry scientist to receive the R.T. Williams Distinguished Scientific Achievement Award. His career stands as a testament to the excellence, innovation, and dedication that define the ISSX community.

Upendra Dahal (Moderator)

Upendra Dahal is currently a Scientific Director in Pharmacokinetic and Drug Metabolism (PKDM) Department at Amgen. He represents PKDM in multi-disciplinary teams from discovery to development, oversees small molecule projects and outsourcing of ADME studies, and supervises scientists and PTRs. Proficient in designing in vitro and in vivo studies to characterize/understand PKDM properties of the drug candidates, provides recommendations to the teams to design better compounds with minimal metabolic and DDI liabilities. Leading the biotransformation group for small molecule drugs, Upendra reviews data, monitors studies, and addresses PKDM challenges to mitigate risks. His role involves preparing as well as reviewing regulatory documents for IND and NDA submissions. Previously worked at Celgene and Pfizer, Upendra boasts diverse research interests, evidenced by a strong track record of peer-reviewed publications across various domains. Upendra received his PhD focusing on enzyme kinetics and drug metabolism from Washington State University under supervision of Prof. Jeff Jones.