The Equivalents Are Coming! Developing a Shared Nomenclature for Radiopharmaceutical Therapy of Neuroendocrine Tumors, Prostate Cancer, and Beyond

As radiopharmaceutical therapy (RPT) expands beyond neuroendocrine tumors and prostate cancer, it is important to understand the U.S. Food and Drug Administration (FDA) approval process and to establish a shared vocabulary for effective communication. The 505(b)(2) New Drug Application is a well-established mechanism for FDA approval of nuclear medicine products. It is an application for drugs that are similar to an approved product, supported by published literature and studies conducted on similar drugs, and bridging studies demonstrating the scientific relevance of the data to the product. This streamlined approval pathway can encourage development of more treatment options, facilitating greater patient access and improved resilience to supply chain disruptions. The evolving RPT landscape necessitates new nomenclature. "Radioligand equivalent" refers to an RPT approved through the 505(b)(2) pathway, distinct from a generic RPT approved through an Abbreviated New Drug Application. Establishing shared terminology supports clear multidisciplinary communication and fosters informed treatment selection.