In the CREST trial, the FDA's critique heavily emphasized an overall survival hazard ratio above one. Though statistically insignificant and based on immature data, this single figure created a powerful suggestion of potential harm that overshadowed the positive primary endpoint and likely contributed to the panel's divided vote.

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Several panelists voted "yes" for approval not because of a compelling risk/benefit profile, but because they believe physicians and patients should have the "option" to choose the therapy. This reveals a philosophy where regulatory approval is seen as a gateway to choice, deferring the final, nuanced risk-benefit decision to the clinic.

The CREST trial showed benefit driven by patients with carcinoma in situ (CIS), while the Potomac trial showed a lack of benefit in the same subgroup. This stark inconsistency demonstrates that subgroup analyses, even for stratified factors, can be unreliable and are a weak basis for regulatory decisions or label restrictions.

When debating immunotherapy risks, clinicians separate manageable side effects from truly life-altering events. Hypothyroidism requiring a daily pill is deemed acceptable, whereas toxicities like diabetes or myocarditis (each ~1% risk) are viewed as major concerns that heavily weigh on the risk-benefit scale for early-stage disease.

The FDA's critique of both CREST and Potomac trials highlights that while event-free survival (EFS) endpoints were met, the lack of improvement in overall survival or prevention of muscle-invasive disease makes the risk/benefit profile questionable for an early-stage cancer, where treatment-related harm is a primary concern.

Praxis Interactive's essential tremor drug succeeded in Phase 3 despite an earlier data monitoring committee (DMC) recommendation to stop for futility. This rare outcome shows that interim analyses on a small fraction of patients can be misleading due to high variance, and continuing a trial against DMC advice can be a winning strategy.

An overall survival (OS) benefit in an adjuvant trial may not be meaningful for patients in systems (e.g., the U.S.) with guaranteed access to the same effective immunotherapy upon recurrence. The crucial, unanswered question is whether treating micrometastatic disease is inherently superior to treating macroscopic disease later, a distinction current trial data doesn't clarify.

A significant criticism of the pivotal KEYNOTE-564 trial is that only half the patients in the control arm received standard-of-care immunotherapy upon relapse. This lack of subsequent optimal treatment complicates the interpretation of the overall survival benefit, raising questions about its true magnitude.

The FDA's current leadership appears to be raising the bar for approvals based on single-arm studies. Especially in slowly progressing diseases with variable endpoints, the agency now requires an effect so dramatic it's akin to a parachute's benefit—unmistakable and not subject to interpretation against historical data.

The CREST trial's positive primary endpoint, assessed by investigators in an open-label setting, was rendered negative upon review by a blinded independent committee. This highlights the critical risk of confirmation bias and the immense weight regulators place on blinded data to determine a drug's true efficacy, especially when endpoints are subjective.

Biohaven's Complete Response Letter (CRL) offers a rare public insight into the FDA's specific statistical objections to using natural history cohorts. The letter details concerns about selection bias and failures in tipping point analyses, serving as a cautionary guide for other companies like Unicure pursuing similar regulatory strategies.