Radioligand Equivalents: Advancing Nomenclature and Understanding the 505(b)(2) Pathway in Neuroendocrine Tumor Treatment
Dr. Aman Chauhan from UCSF moderated a discussion with Dr. Andrew Hendifar from Cedars-Sinai Medical Center, Dr. Heloisa Soares from University of Utah Health, and Dr. Ghassan El-Haddad from Moffitt Cancer Center on the emerging regulatory and nomenclature landscape for radioligand therapy in neuroendocrine tumors (NETs). The program introduced the term radioligand equivalent (RLE) to describe products approved through the FDA's 505(b)(2) pathway, a mechanism accounting for 55% of new drug applications approved between 2020 and 2024, yet unfamiliar to many clinicians. The discussion distinguished RLEs from both novel reference-listed drugs (approved via 505(b)(1)) and generics (approved via abbreviated new drug application), explained the scientific bridging requirements, and explored practical implications for formulary decisions, multidisciplinary communication, staff education, and patient counseling. Key themes included supply chain resilience, institutional infrastructure preparation for different waste-handling requirements between carrier-added and non-carrier-added products, barriers to RLE adoption, and the potential for RLE terminology and the 505(b)(2) pathway to accelerate innovation across an expanding radioligand therapy landscape.
