A research team disclosed an intelligent design framework for adeno‑associated virus (AAV) vectors that selectively activate within the tumor microenvironment (TME). The engineered AAVs incorporate sensor elements that detect TME cues and modulate transgene expression, improving tumor targeting while limiting off‑tumor exposure. The approach addresses a persistent delivery bottleneck for viral gene therapies—achieving both specificity and potency—by making vector activity conditional on local biology. AAVs are the most commonly used delivery vehicle in gene therapy; conditioning their activity on tumor signals could reduce systemic toxicity and increase therapeutic windows.