Naples, Florida-based Attralus, Inc. announced receipt of US FDA orphan drug designation for zamubafusp alfa (AT-02) for the treatment of immunoglobulin light chain (AL) amyloidosis, a rare and progressive multiorgan disease for which no approved therapy currently targets amyloid removal directly.
The designation may provide development incentives including tax credits, user-fee exemptions, and, if ultimately approved for the indication, seven years of US orphan exclusivity.
The AL amyloidosis orphan drug designation is the fourth such designation zamubafusp alfa has received globally. The drug previously received FDA orphan drug designation for transthyretin-associated amyloidosis (ATTR), and the European Medicines Agency’s Committee for Orphan Medicinal Products adopted positive opinions for orphan medicinal product designations for zamubafusp alfa in both ATTR and AL amyloidosis. In the EU, orphan drug designation provides a 10-year period of marketing exclusivity following product approval, along with incentives including protocol assistance from the EMA and direct access to the centralized authorization procedure.
The current standard of care in AL amyloidosis — the combination of daratumumab, cyclophosphamide, bortezomib, and dexamethasone (dara-CyBorD) — targets the underlying plasma cell clone responsible for producing toxic light chains. Achieving deep hematologic response suppresses new amyloid formation, but existing amyloid deposits in organs such as the heart and kidneys are not cleared by these agents. Patients who achieve hematologic remission but retain organ dysfunction represent a population with no approved therapeutic option targeting the amyloid itself.
Zamubafusp alfa is designed to address this gap. The molecule is a humanized IgG1 monoclonal antibody genetically fused with Attralus’s proprietary pan-amyloid binding peptide. The peptide component binds broadly to amyloid fibrils across multiple types, while the antibody’s Fc region engages the immune system — specifically stimulating macrophage-mediated phagocytosis — to clear the bound amyloid deposits from affected organs and tissues. Preclinical data demonstrated binding to multiple amyloid types in major organs, induction of macrophage-mediated phagocytosis, and amyloid removal. Because the peptide targets a structural feature common to amyloid fibrils rather than a protein-specific epitope, the molecule is described by Attralus as a pan-amyloid removal (PAR) therapeutic, with potential application across amyloidosis subtypes. Attalus is testing zamubafusp alfa in an ongoing Phase II open-label trial in AL amyloidosis patients.
The AT-02 orphan drug designation for arrives as the competitive landscape for this indication is becoming more active. Los Angeles-based Immix Biopharma, Inc. (Nasdaq: IMMX) is advancing NXC-201, a BCMA-targeted CAR-T cell therapy, through the Phase II NEXICART-2 trial in relapsed/refractory AL amyloidosis, with topline results expected in Q3 2026. In a recent interim update, Immix reported a 95% complete response rate in the first 20 evaluable patients — a result that, if sustained, could position NXC-201 as the first approved therapy specifically for relapsed/refractory AL amyloidosis. NXC-201 and zamubafusp alfa are mechanistically and strategically distinct: NXC-201 targets the plasma cell clone producing toxic light chains, while zamubafusp alfa targets the amyloid deposits themselves. The two approaches could potentially be complementary rather than competing in a treatment algorithm.
AL amyloidosis affects an estimated 74,000 patients worldwide, with approximately 25,000 in the United States and around 4,500 new diagnoses annually. The disease most commonly involves the heart and kidneys, and patients in hematologic remission with persistent organ dysfunction have no approved amyloid-depleting option. Zamubafusp alfa’s development is specifically oriented toward this population.
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