The Destiny Breast 11 trial compared a new drug to a chemotherapy regimen (ACTHP) that many US oncologists no longer use. This choice of a less common control arm makes it difficult for them to directly compare the new treatment's efficacy against their own current standard (TCHP), complicating adoption.

A lack of representation in genomic data has direct clinical consequences. A deep understanding of European genetics and a poor understanding of other groups has already manifested in less precise medical treatments for non-European populations, undermining the core promise of precision medicine.

Despite strong efficacy data, the drug DV-Toripalimab scored lower than a competitor (2.5 vs 3.0). Experts attribute this confidence gap to its Phase 3 trial being conducted only in China, which raises generalizability concerns and reflects a lack of hands-on experience for Western physicians.

The STARGLO trial (glofitamab-gemox) showed a strong survival benefit in Asia-Pacific patients but not in the small North American cohort. This geographic discrepancy, with only 9% of patients from the US, was a key reason the FDA did not approve the combination, while European agencies did.

To de-risk clinical programs from recruitment and activation hurdles within the UK's strained NHS, companies like Resolution Therapeutics run an equal number of trial sites in other countries, like Spain. This geographic diversification provides a valuable real-time benchmark and a hedge against single-country operational delays.

The FDA is requiring higher US patient enrollment in global trials to address concerns that results from predominantly non-US populations (e.g., Asia) may not be generalizable. This reflects worries about differences in prior standard-of-care treatments and potential pharmacogenomic variations affecting outcomes.

Even when trials like LITESPARK 022 and Keynote 564 use identical eligibility criteria, outdated staging systems result in patient populations with different underlying risks. This makes direct comparison of outcomes between trials, even for the same drug, an unfair and statistically flawed analysis that ignores the function of a control arm.

Even with positive results from two registrational Phase 3 trials, experts note a potential regulatory hurdle. The FDA has shown increasing concern over studies with a low proportion of patients from North America, a characteristic of these trials, potentially complicating an otherwise strong case for approval based on clinical merit.

Amidst growing uncertainty at the US FDA, biotech companies are using a specific de-risking strategy: conducting early-stage clinical trials in countries like South Korea and Australia. This global approach is not just about cost but a deliberate move to get fast, reliable early clinical data to offset domestic regulatory instability and gain a strategic advantage.