中文摘要
专利可以激励创新，但制药企业往往通过为现有药物的细微改动申请专利来延长市场独占期，这引发了人们对治疗价值甚微的低新颖性专利的担忧。本研究考察上市许可后专利申请行为如何变化——上市许可是一项监管里程碑，它会使临床试验数据公开，从而形成限制未来专利权利要求的“现有技术”。我们使用一个新构建的欧洲专利—药物数据集和事件研究方法，利用从专利优先权申请到获得上市许可所需时间中可合理视为外生的变异。我们发现，上市许可后策略性专利申请显著减少，这种下降在次级专利以及涵盖相同疾病领域的专利中尤为明显。相比之下，后续产品专利和新疾病领域专利保持稳定，这表明上市许可选择性地遏制了低新颖性专利申请。原研企业和其他企业的反应相似，但反应速度不同。较早的里程碑之后并未出现类似反应，这表明获得低价值专利或对其进行权利执行的难度上升，可能是其作用机制。稳健性检验——包括采用其他双重差分估计量、使用独占期恒定样本，以及在分析中考虑非欧洲市场激励、企业特征和工具变量方法——支持我们的结论。我们的研究结果表明，监管数据透明度可以间接提高专利质量。
Abstract
Patents can incentivize innovation, but pharmaceutical firms often extend market exclusivity by patenting minor modifications to existing drugs, raising concerns about low-novelty patents that add little therapeutic value. This study examines how patenting behavior changes after marketing authorization, a regulatory milestone that makes clinical trial data public and thereby creates “prior art” that limits future patent claims. Using a novel European patent–drug dataset and event study methods, we exploit plausibly exogenous variation in the time from patent priority filing to marketing authorization. We find a significant decline in strategic patenting after authorization, particularly in secondary patents and those covering the same disease areas. In contrast, follow-on product patents and patents for new disease areas remain stable, suggesting that authorization selectively curbs low-novelty filings. Both originators and other firms respond similarly, though at different speeds. The absence of similar responses after earlier milestones indicates increased difficulty in obtaining or enforcing low-value patents as the likely mechanism. Robustness checks – including alternative difference-in-differences estimators, constant exclusivity samples, and analyses accounting for non-European market incentives, firm characteristics, and instrumental variable approaches – support our conclusions. Our findings show how regulatory data transparency can indirectly improve patent quality.