Follow-On Cancer Drugs Target Earlier Stages Than Initial Drugs: Implications Of The IRA

The Inflation Reduction Act (IRA) of 2022 mandates price negotiations for certain drugs under Medicare, shortening the exclusivity period historically used to recoup research and development investments and support follow-on innovation. This article characterizes the clinical significance of follow-on oncology drug approvals, using a novel data set of Food and Drug Administration oncology drug approvals from the period 2000-24. We found that, compared with initial approvals, follow-on drugs target earlier disease stages, where therapeutic success is often more likely. Among 184 cancer drugs analyzed, 41.8 percent had at least one follow-on approval, with 59.7 percent of those targeting earlier disease stages than the original approval. The average reduction in disease stage between original indication approval and follow-on approval was 0.54. The shortened exclusivity period under the IRA may have influenced these development trajectories. One potential effect is a shift from depth-oriented development toward horizontal expansion across tumor types or patient populations. This shift may disproportionately affect small-molecule drugs, which (compared with biologics) more commonly rely on sequential, indication-by-indication development.