Protego Bets on a New Path for Amyloidosis With $130M Raise

San Diego–based Protego Biopharma has raised $130 million in Series B funding to advance a new therapeutic approach for AL amyloidosis , a rare and often fatal disease caused by misfolded antibody fragments known as light chains. The company’s lead drug, PROT-001 , is designed to stabilize these proteins before they misfold and accumulate — a shift from the traditional strategy of treating the damage after it occurs. Early clinical data is expected next year, with a Phase 2/3 trial planned for the second half of 2026.

The timing is significant. Several competitors have stumbled recently: both ProthenaDealroom has a profile for this one. Try Dealroom → and AstraZeneca saw their amyloidosis programs fall short in clinical testing this year, despite years of investment. Those failures targeted the removal of existing toxic deposits. Protego is betting that intervening earlier — before the proteins clump together — may offer a more direct way to slow or halt the disease’s progression. CEO Brent WarnerDealroom has a profile for this one. Try Dealroom → argues that growing scientific evidence points to these unstable light chains as the core driver of organ damage and mortality.

Protego’s strategy draws from the work of Jeffery Kelly , a Scripps Research scientist and co-founder of the company. Kelly previously helped develop Vyndamax , the first U.S.-approved stabilizer for transthyretin amyloidosis, now a blockbuster drug under Pfizer. That precedent matters: it demonstrated both the scientific and commercial potential of protein-stabilizing therapies, and it laid the foundation for Protego’s belief that misfolding can be intercepted rather than merely managed.

If PROT-001 can validate that approach, it could complement — and potentially improve — existing treatments like Darzalex and chemotherapy, which aim to eliminate the plasma cells producing the misfolded proteins. Patients often relapse because some of those cells eventually return. Adding a stabilizer, Warner says, could lead to “faster, deeper, and more durable responses.” In his words: “You don’t always need a sledgehammer — sometimes a sharper knife will do.”

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Biopharma DIVE
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