WATERTOWN, Mass.–Palleon Pharmaceuticals, a clinical-stage biotechnology company developing treatments for autoimmune diseases and cancer, has reported positive early results from a Phase 2 clinical trial evaluating its experimental therapy HLX79/E-602 in patients with primary membranous nephropathy, a rare autoimmune kidney disease.
The findings, presented at the American College of Rheumatology’s ACR Convergence 2026 meeting in Orlando, showed that combining HLX79/E-602, also known as efgitasialase alfa, with rituximab produced faster and more substantial treatment responses than rituximab alone.
The randomized Phase 2 study was conducted in China by Palleon’s development partner, Shanghai Henlius Biotech, and enrolled 26 patients with primary membranous nephropathy.
Researchers evaluated three doses of HLX79/E-602—10, 20, and 30 mg/kg—in combination with Henlius’ rituximab biosimilar, HANLIKANG. The treatment was administered weekly for four weeks, with additional dosing at six months.
Rituximab, which targets B cells involved in autoimmune activity, is an established treatment for primary membranous nephropathy. However, patients may require several months to respond, and approximately half achieve remission.
In the Phase 2 trial, patients receiving the highest dose of HLX79/E-602 in combination with rituximab achieved complete or partial remission in a median of three weeks, compared with 11 weeks among patients receiving rituximab alone.
By week 36, all seven patients receiving the 30 mg/kg combination had achieved complete or partial remission, including three patients who experienced complete remission.
In comparison, three of six patients, or 50%, receiving rituximab alone achieved remission during the same period.
The company reported that the combination treatment was well tolerated across all evaluated doses, with no severe adverse events attributed to HLX79/E-602.
The findings provide early evidence that the investigational therapy could improve treatment outcomes when administered alongside existing B-cell-targeting therapies. However, the small number of patients means additional clinical studies will be necessary to confirm its effectiveness and safety.
“Growing evidence suggests that macrophages persist in the kidney after B cells are gone and continue to drive damage. HLX79/E-602 reduces pro-fibrotic macrophages in inflamed tissue without compromising the beneficial functions macrophages perform elsewhere in the body,” said Jim Broderick, M.D., Chief Executive Officer and Founder of Palleon Pharmaceuticals. “As these macrophages are an important driver of progressive organ damage in many autoimmune conditions beyond pMN, including lupus nephritis, systemic sclerosis, and interstitial lung disease, this mechanism offers a potential new path forward for addressing unmet needs in rheumatology.”
HLX79/E-602 is a first-in-class sialidase-Fc fusion protein designed to modify sugar molecules on cell surfaces through a process known as glycan editing.
The therapy uses a sialidase enzyme to remove sialic acid from cell surfaces, targeting populations of CD163-positive macrophages associated with inflammation and tissue scarring.
Macrophages are immune cells that play important roles in defending the body against infection and maintaining tissue health. However, certain macrophage populations can also contribute to chronic inflammation, fibrosis, and progressive organ damage.
Palleon’s approach is designed to reduce the activity of harmful macrophages in inflamed tissues while preserving their beneficial functions elsewhere in the body.
The company believes the mechanism could have applications beyond primary membranous nephropathy, including autoimmune conditions such as lupus nephritis, systemic sclerosis, and interstitial lung disease.
The Phase 2 findings represent an early clinical assessment of HLX79/E-602’s potential to improve treatment responses in autoimmune kidney disease.
