The FDA approved Travere's drug for the kidney disease FSGS based on the surrogate endpoint of proteinuria, despite the drug failing on the traditional eGFR endpoint. This decision, following a company-backed effort to validate proteinuria, suggests increased regulatory flexibility and creates a new pathway for kidney disease drug approvals.

Minimal Residual Disease (MRD) negativity is now recognized by regulators as a surrogate endpoint in oncology. Because it is considered 'reasonably likely to predict progression-free survival,' this shift allows drug developers to use MRD data to support accelerated approval pathways, expediting the availability of new therapies.

For its alpha-1 antitrypsin deficiency program, Beam aligned with the FDA on an accelerated approval pathway based on a surrogate endpoint: restored alpha-1 protein levels. This strategy allows for faster market entry, with a longer-term confirmatory trial measuring clinical outcomes like lung and liver function running in parallel.

After a decade on the market and multiple shifts in endpoints, Sarepta's definitive Phase 3 study for its DMD drugs failed. This outcome casts doubt on the entire accelerated approval framework for slowly progressive diseases, where surrogate endpoints may not translate to clinical benefit, leaving regulators and patients in a difficult position.

The FDA now allows a single, well-designed pivotal trial instead of the traditional two. This reform significantly cuts costs by $100M-$300M and shortens development timelines, enabling companies to test twice as many potential drugs with the same capital.

The successful use of a surrogate endpoint (proteinuria reduction) for IgA nephropathy approvals has created a clear regulatory pathway. This blueprint is now being leveraged by developers to advance therapies for other previously untreatable renal diseases like FSGS, de-risking their clinical programs.

Skeletalis's platform targets osteoporosis with precision using "site-specific pharmacology." A small molecule anchors an inactive prodrug to the bone, where it is activated only by the cells causing bone loss. This localized approach dramatically improves the safety profile and therapeutic index, enabling the use of novel biological targets that would be too risky for systemic delivery.

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.

For lifelong conditions like osteoporosis, drugs whose effects plateau after 1-2 years create treatment uncertainty for patients and providers. The goal should be therapies that provide a sustained, linear benefit without a ceiling. This is achieved by respecting the body's natural biology (e.g., bone remodeling) while precisely intervening only in the disease process.