Building the Bridge: Molecular Imaging Biomarkers for 21st Century Cancer Therapies

Precision medicine, in which the molecular underpinnings of the dis-ease are assessed for tailored therapies, has greatly impacted cancer care. In parallel, a new pillar of therapeutics has emerged with pro-found success, including immunotherapies such as checkpoint inhibi-tors and cell-based therapies. Nonetheless, it remains essential to develop paradigms to predict and monitor for therapeutic response. Molecular imaging has the potential to add substantially to all phases of cancer patient care: predictive, companion diagnostics can illumi-nate therapeutic target density within a tumor, and pharmacodynamic imaging biomarkers can complement traditional modalities to judge a favorable treatment response. This "Focus on Molecular Imaging" arti-cle discusses the current role of molecular imaging in oncology and highlights an additional step in the clinical paradigm termed a thera-peutic biomarker, which serves to assess whether next-generation drugs reach their target to elicit a favorable clinical response.