Protego Biopharma has secured $130 million in an oversubscribed Series B funding round to advance its light chain amyloidosis program. The California-based company plans to use the funds to initiate a pivotal clinical trial for PROT-001, an investigational small-molecule drug designed to treat the rare disorder. A specific timeline for the registrational study was not disclosed.
The Series B round was led by Novartis Venture Fund and Forbion, with participation from new investors YK Bioventures, Digitalis Ventures, and Droia Ventures.
Light chain (AL) amyloidosis affects between nine and 14 people per one million in the United States. The disease occurs when misfolded light chain proteins accumulate in organs such as the heart and kidneys, impairing their function. Symptoms can include carpal tunnel syndrome, numbness in extremities, shortness of breath, fatigue, and can be fatal in severe cases.
According to the company’s announcement, PROT-001 is a small molecule drug that acts as a “guide” to help target proteins fold correctly. By stabilizing these proteins and preventing toxic buildup, PROT-001 aims to address what Forbion Principal Tim Lohoff described as the “root cause” of AL amyloidosis. Lohoff said: "Through this mechanism, PROT-001 stabilizes the light chain proteins and prevents the buildup of toxic, misfolded amyloid, in turn offering a therapeutic option that targets the ‘root cause’ of the disease."
Protego was founded in 2017 by Jeffery Kelly, a protein folding expert at Scripps whose research contributed to FoldRx—acquired by Pfizer in 2010—and helped develop drugs for transthyretin amyloidosis.
The fundraising comes amid several large investments in biotech during 2025. Isomorphic Labs raised $600 million earlier this year for AI-powered drug design development. Verdiva Bio secured $411 million in an oversubscribed Series A round focused on obesity treatments. Other notable financings include Artios Pharma’s $115 million Series D for oncology research and hair loss biotechs Veradermics and Pelage Pharmaceuticals raising $150 million and $120 million respectively.
