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Surrogate Endpoints

17
Feb
4 min read

When Tumor Shrinkage Doesn't Mean Living Longer

In 2019, FDA granted accelerated approval to voxelotor for sickle cell disease based on a surrogate endpoint: hemoglobin increase. The mechanism was sound. Voxelotor increased hemoglobin oxygen affinity, which should reduce sickling and improve outcomes. The biology made sense. The FDA agreed. Patients got access. In September 2024, the drug

05
Feb
4 min read

The Post-Hoc Problem: Why Bayesian Pre-Specification Matters More Than the Philosophy

The Bayesian vs. frequentist debate usually centers on philosophy. Priors are subjective! No, they formalize existing knowledge! You're smuggling in assumptions! You're ignoring relevant information! It's a fun argument. It's also the wrong one, at least for regulatory decision-making. The real value

27
Jan
7 min read

Qalsody: The Probability of Harm

What FDA Actually Decided When the Trial Failed