Novo Nordisk announced during its second quarter 2025 earnings call on August 6 that it will advance coramitug into Phase 3 development for transthyretin amyloidosis with cardiomyopathy (ATTR-CM) before the end of 2025, following successful completion of a Phase 2 trial. The potential first-in-class amyloid depleter antibody was originally developed by Prothena Corporation and acquired by Novo Nordisk in July 2021.
Phase 2 Trial Results Drive Advancement Decision
The Danish pharmaceutical company successfully completed a Phase 2 trial investigating coramitug's efficacy and safety in 105 patients with ATTR cardiomyopathy. The study evaluated once-monthly intravenous doses of coramitug compared to placebo over 52 weeks, with primary endpoints including functional measures such as the six-minute walking test (6MWT) and changes in NT-proBNP levels.
While detailed trial data has not yet been released, Novo Nordisk confirmed that results will be presented at a medical conference later this year. The positive outcomes were sufficient to support the company's decision to proceed with Phase 3 development.
Unique Mechanism of Action Targets Amyloid Depletion
Coramitug represents a differentiated approach to treating ATTR amyloidosis through its proposed mechanism of depleting both deposited amyloid to improve organ function and circulating non-native transthyretin (TTR) to prevent further organ deposition. The investigational antibody is designed to target amyloid associated with disease pathology in both hereditary and wild-type ATTR amyloidosis while preserving the native, normal tetrameric form of the protein.
In preclinical studies, coramitug demonstrated the ability to inhibit amyloid fibril formation, bind soluble aggregate forms of non-native TTR, and promote clearance of insoluble amyloid fibrils through antibody-mediated phagocytosis. A Phase 1 clinical study showed that coramitug was well tolerated in patients with hereditary ATTR amyloidosis and demonstrated potential clinical activity on Global Longitudinal Strain (GLS) and Neuropathy Impairment Score (NIS).
Addressing Critical Unmet Medical Need
"We are excited by Novo Nordisk's decision to advance coramitug into Phase 3 development. There remains a significant unmet need in patients with ATTR amyloidosis with cardiomyopathy, who are at high risk for early mortality and significant morbidity due to amyloid deposition in vital organs," said Gene Kinney, Ph.D., President and Chief Executive Officer of Prothena.
The differentiated depleter mechanism of action positions coramitug as a potential monotherapy approach to ATTR amyloidosis that might also complement existing therapeutic approaches, which either stabilize or reduce production of the native TTR tetramer.
Financial Implications and Market Response
Under the acquisition agreement, Prothena is eligible to receive up to $1.2 billion upon achievement of clinical development and sales milestones, including $100 million earned to date. The company will earn an additional clinical milestone payment when prespecified enrollment criteria are met in the Phase 3 clinical trial.
Market response to the announcement was positive for Prothena, with stock prices rising from $7.03 at market close on August 5 to $7.45 at market open on August 6, representing a 5.97% increase.
Competitive Landscape in ATTR Therapeutics
The ATTR cardiomyopathy treatment landscape has seen recent developments with both successes and setbacks. Alnylam's Amvuttra (vutrisiran) gained European Commission approval in June 2025, three months after FDA approval in March. Other approved therapies include Pfizer's Vyndamax (tafamidis) and BridgeBio Pharma's Attruby (acoramidis).
However, the field has also experienced challenges, including Intellia Therapeutics facing a serious adverse event in a Phase 3 trial of its ATTR cardiomyopathy gene therapy, and Prothena's own setback in May 2025 when birtamimab missed its primary endpoint in a Phase 3 AL amyloidosis study.
Novo Nordisk gained full worldwide rights to the intellectual property and related rights of the ATTR amyloidosis business and pipeline acquired from Prothena, positioning the company to advance coramitug through late-stage development and potential commercialization.
