Physician–scientist trained at Yale (B.A., summa cum laude) and the University of Pennsylvania (M.D.), with residency at Penn–Presbyterian and fellowship in Hematology/Oncology at UC San Diego. Early NIH-supported work at The Wistar Institute in tumor immunology, followed by a Physician–Scientist Award in cancer biology and cellular senescence, established a foundation in mechanistic cancer research.

Founded the San Diego Cancer Center (1991; later integrated into UC San Diego), leading it for two decades as a major regional oncology institution and clinical trial site during the emergence of genome-targeted therapy. Contributed to early adoption and clinical integration of molecularly guided treatment strategies.

Founding Director of WebMD (1998–2017), guiding the integration of physician (Medscape) and public platforms into a leading global medical information and education system—positioned at the early intersection of medicine and the internet. Board roles include CareInsite, Medical Manager, HLTH, and Forian (NASDAQ), reflecting ongoing leadership in healthcare data and informatics.

Current work focuses on next-generation cancer diagnostics and therapeutics: at XZOM, advancing exosome-based liquid biopsy approaches for early detection; at TRACT Bio, developing therapeutic strategies targeting cancer stem cell systems and regenerative tumor architecture.

Across academic research, clinical leadership, and digital medicine, his work has remained oriented toward the same problem: how to define cancer at the level of mechanism and use that definition to improve detection, treatment, and durability of response.