Comparing supplemental indications for cancer drugs approved in the US and EU

IMPORTANCE: Cancer drugs initially granted regulatory approval for one disease may also prove useful in treating other diseases. In these cases, manufacturers may seek to add supplemental indications to their drug labels. The extent to which manufacturers seek supplemental indications for cancer drugs may differ in the US and EU.

OBJECTIVE: To investigate how manufacturers have pursued supplemental indications for cancer drugs approved in the US vs. EU.

METHODS: We performed a retrospective observational cohort study of cancer drugs first approved in the US and EU from 2005-2022 to compare the rate at which supplemental indications are added to drug labels and the times to first, second, and third supplemental indications.

RESULTS: Among 129 cancer drugs approved in both the US and EU from 2005-2022, approval occurred an average of 0.79 years earlier in the US. These drugs had a total of 145 indications at the time of approval in the US and 144 indications in the EU. Supplemental indications were granted at a rate of 0.22 per drug-year in the US, compared to 0.17 per drug-year in the EU (incidence rate ratio=1.30, 95 % confidence interval [CI]: 1.06-1.60, p = 0.01). This resulted in a total of 221 approved supplemental indications in the US and 152 approved supplemental indications in the EU through October 1, 2023. The times to the first and second supplemental indications were similar across the two jurisdictions, while the time to the third supplemental indication was shorter in the US (hazard ratio: 2.06, 95 % CI: 1.03-4.14, p = 0.04).

CONCLUSIONS AND RELEVANCE: Manufacturers obtained supplemental indications for cancer drugs in the US at a higher rate than in the EU, which could be due to variable regulatory requirements and/or different market forces.