A Frontiers in Nuclear Medicine review proposes an evidence-gated translation roadmap explaining why some promising PET tracers fail to reach clinical utility. The framework distinguishes established PSMA and somatostatin receptor theranostics from less mature platforms such as FAP, HER2 and CXCR4. The authors emphasize that clinical translation is not only about imaging signal but also about reproducible clinical endpoints, assay validity, and translational readiness. The roadmap is positioned as a structured way to separate mature theranostic classes from earlier, more uncertain candidates. For industry stakeholders, the review provides a decision template for portfolio triage—helping teams manage capital allocation and avoid late-stage setbacks when evidence does not support broad clinical deployment.