The RLT investment thesis is backwards. BD teams are filtering for clinical milestones - Phase III data, pivotal trials, durable responses - and treating manufacturing as secondary diligence. The data shows manufacturing viability is the primary gate, and most clinically advanced assets fail it.

Sleuth analyzed 122 clinically-viable oncology RLTs (Phase II+ with trial maturity supporting registrational potential). 84% of Phase III and approved assets remain supply-constrained despite proven clinical efficacy. Manufacturing scalability separates winners from regional players more decisively than clinical differentiation.

The nuance: not all production routes face identical constraints. Generator-produced radionuclides (Tc-99m, Ga-68, Y-90) solve distribution through on-site hospital radiolabeling. Select reactor assets like Pluvicto and Lutathera built dedicated supply infrastructure. But most reactor programs and virtually all cyclotron programs face structural regional barriers.

Cyclotron distribution is bounded by decay physics - half-lives measured in hours prevent profitable cross-continent shipping. Reactor capacity is concentrated in aging facilities prone to shutdowns. Building Lu-177 supply at Pluvicto scale required years of dedicated partnerships. New programs betting on reactor production assume solved infrastructure that doesn't exist for most assets.

Generator-based production eliminates these constraints. A Mo-99/Tc-99m generator in a hospital pharmacy enables on-site radiolabeling without external supply dependence. These systems collapse the supply chain from global logistics to local chemistry. The manufacturing moat isn't better science - it's eliminated distribution risk.

The strategic error is treating advanced clinical stage as de-risked commercialization. A Phase III reactor-dependent RLT with compelling efficacy is still betting on supply infrastructure that took years to build for Lutathera and Pluvicto. When AbbVie acquired Capstan for $2.1B, they were buying manufacturing independence where supply solutions are entirely new builds.

Three portfolio implications:

First, manufacturing due diligence should precede clinical due diligence. If production route is reactor or cyclotron without solved distribution infrastructure, the addressable market ceiling is regional regardless of efficacy.

Second, discount Phase III valuations for assets with unresolved manufacturing. Clinical success proves efficacy but not commercialization potential.

Third, recognize that manufacturing constraints create whitespace. I&I, neurology, and rare disease indications where RLT competition is sparse often have sparse competition because manufacturing hasn't been solved there yet.

Manufacturing viability is not a back-office problem. It's the binding constraint determining which clinically viable RLTs achieve commercial scale and which remain regional products regardless of efficacy.