中文摘要
专利可以激励创新，但制药企业常常通过对现有药物进行细微修改申请专利来延长市场独占期，由此引发了对新颖性较低、几乎不增加治疗价值的专利的担忧。本研究考察专利申请行为在上市许可——这一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”的监管里程碑——之后如何变化。利用一个新构建的欧洲专利—药物数据集和事件研究方法，我们利用从专利优先权申请到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，尤其是次级专利以及涵盖相同疾病领域的专利。相比之下，后续产品专利和针对新疾病领域的专利保持稳定，表明上市许可有选择地抑制了低新颖性专利申请。原研企业与其他企业的反应相似，但反应速度不同。在更早的里程碑之后未出现类似反应，这表明低价值专利更难获得授权或执行，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、使用独占期不变样本，以及考虑非欧洲市场激励、企业特征和工具变量方法的分析——均支持我们的结论。研究结果表明，监管数据透明度能够间接提高专利质量。
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.