Palleon Pharmaceuticals, a privately held biotechnology company based in Waltham, Massachusetts, announced on October 16, 2026, that it will present interim Phase 2 clinical results for HLX79, also known as E-602, at the American College of Rheumatology’s ACR Convergence meeting in Orlando, Florida. The investigational human sialidase enzyme therapy is being evaluated with HLX01, a rituximab biosimilar developed by Shanghai Henlius Biotech, in patients with membranous nephropathy. The oral presentation is scheduled for November 11 and will examine whether removing selected cell-surface sugar structures can improve immune regulation and kidney disease responses.
A publicly available ACR abstract reports that 17 of 26 patients, or approximately 65%, achieved complete or partial remission within 12 to 24 weeks. Higher-dose cohorts showed particularly encouraging proteinuria responses, with a reported response rate of 78% in the 20 mg/kg and 30 mg/kg groups at their respective evaluation points. However, the interim study remains blinded and includes patients receiving rituximab with placebo rather than HLX79, meaning the overall response figures cannot yet be interpreted as the confirmed treatment effect of adding the experimental enzyme.
Palleon and Henlius initiated the study in China in August 2025 under their autoimmune disease development collaboration. The programme represents one of the most advanced clinical applications of Palleon’s glycan-editing technology and follows earlier Phase 1 work establishing initial tolerability and biological activity. The company has also scheduled a related presentation at the American Society of Nephrology’s Kidney Week on October 23, giving researchers an opportunity to examine the emerging kidney disease findings before the ACR meeting.
The scientific objective is important because rituximab has become an established treatment for primary membranous nephropathy, but some patients respond slowly or fail to achieve adequate disease control. Palleon believes modifying sialic acid structures on immune cells may improve the efficiency of B-cell depletion and alter immune pathways involved in kidney injury. The forthcoming unblinded analysis will be necessary to determine whether the combination actually outperforms rituximab alone.
What does the interim Phase 2 response rate establish about HLX79?
The ACR abstract describes a double-blind, placebo-controlled Phase 2 study registered as NCT07038382. Patients with primary membranous nephropathy were randomized in a three-to-one ratio to receive HLX79 plus HLX01 or placebo plus HLX01. The trial evaluated three HLX79 dose levels of 10, 20 and 30 mg/kg, with all participants receiving the rituximab biosimilar.
The interim analysis covered 26 patients across three cohorts. In the first cohort, seven patients were evaluable at the reported assessment, with three achieving partial remission by Week 24. In the second cohort, seven of nine achieved complete or partial remission at Week 24, including one complete response and six partial responses.
The third cohort showed seven partial responses among nine evaluable patients at Week 12. These findings suggest that substantial reductions in disease-related protein loss may occur relatively early during treatment. However, the response rates were reported within blinded cohorts rather than as a complete comparison between patients receiving HLX79 and those receiving its placebo.
The distinction is central to interpreting the findings. All participants received rituximab, which is itself an effective treatment for membranous nephropathy. The current results therefore support further examination of the combination but do not yet establish how much additional benefit comes from the sialidase enzyme.
The ACR abstract also describes reductions in proteinuria accompanied by increases in serum albumin. These measurements are clinically relevant because excessive urinary protein loss and reduced blood albumin are important manifestations of membranous nephropathy. Detailed numerical results and the treatment-arm comparison will provide stronger evidence about the magnitude of these changes.
Why is achieving remission within 12 to 24 weeks potentially important?
Membranous nephropathy is an autoimmune kidney disease in which immune deposits develop along structures involved in filtering blood. This can damage the filtration barrier and allow substantial amounts of protein to escape into urine. Patients may experience swelling, low serum albumin and complications associated with nephrotic syndrome.
Treatment aims to control the immune processes responsible for injury while reducing protein loss and preserving kidney function. However, improvement after B-cell-directed treatment can take time because circulating antibodies, kidney deposits and tissue recovery do not necessarily change at the same rate. A biological response may occur before a measurable improvement in proteinuria becomes apparent.
The landmark MENTOR trial established the clinical importance of rituximab in primary membranous nephropathy. In that randomized study, 60% of patients receiving rituximab achieved complete or partial remission at 12 months, with the same composite rate maintained at 24 months. Results from the current Palleon programme are being evaluated against this established treatment background.
Earlier remission could be valuable if it reduces the duration of severe proteinuria and its associated complications. Nevertheless, the populations, dosing schedules and assessment methods differ between the trials. Comparing their percentages cannot establish that HLX79 produces faster or superior remission.
The published ACR abstract points to encouraging early activity, but a direct, unblinded comparison within the current randomized study remains the more reliable way to evaluate the added value of the experimental medicine.
How does HLX79 use sialidase activity to modify immune cells?
HLX79 is a human sialidase-Fc fusion protein designed to remove sialic acid residues from selected glycans on cell surfaces. Glycans are carbohydrate structures attached to proteins and lipids, and they influence how cells communicate with their surrounding environment. Sialic acids can participate in recognition pathways that regulate immune-cell activity.
Palleon’s approach, known as glycan editing, seeks to modify these structures directly rather than blocking one conventional inflammatory receptor. The company believes removing particular sialic acid residues may alter inhibitory immune interactions and increase the susceptibility of disease-associated cells to therapeutic antibodies. The technology originated from research into the biological functions of glycans and their role in immune regulation.
In membranous nephropathy, the intended benefit involves improving the effectiveness of rituximab-mediated B-cell depletion. Rituximab binds CD20 on B cells and promotes their removal through immune mechanisms. Palleon has reported preclinical findings suggesting that sialidase treatment can enhance antibody-associated cell destruction.
However, changing cell-surface glycans may influence more than one immune-cell population. The biological consequences can depend on the tissue, degree of desialylation and duration of exposure. Careful evaluation of safety and immune function is therefore essential.
The Phase 2 trial includes exploratory biomarker assessments intended to investigate whether the proposed mechanism occurs in patients. These include anti-PLA2R antibodies, circulating B-cell subsets and urinary markers associated with macrophage activity. Such measurements may help connect biological activity with the observed changes in proteinuria.
Why is rituximab an important comparator in membranous nephropathy?
Primary membranous nephropathy is frequently associated with autoantibodies directed against proteins expressed in the kidney, particularly the phospholipase A2 receptor. These antibodies contribute to immune-mediated injury of the glomerular filtration barrier. Suppressing the responsible B-cell response can reduce the production of pathogenic antibodies and support remission.
Rituximab has become an important therapeutic option because it targets CD20-positive B cells without requiring the same mechanism of broad cytotoxic immunosuppression used by some older treatments. Its efficacy has been supported by randomized clinical studies, although patients with severe disease or persistent autoantibody activity may respond inadequately. Treatment choice still depends on disease risk, kidney function and individual medical circumstances.
The MENTOR trial compared rituximab with cyclosporine in 130 patients. At 24 months, complete or partial remission was achieved in 60% of the rituximab group compared with 20% receiving cyclosporine. The findings helped establish sustained B-cell depletion as an effective strategy in suitable patients.
The Palleon programme builds on that treatment foundation rather than replacing rituximab outright. Its question is whether adding HLX79 can produce deeper or faster responses through more effective immune modulation. A benefit would be meaningful only if improvements justify the additional treatment exposure and potential risks.
Direct comparison is therefore essential. A high remission rate among patients receiving both treatments would be encouraging, but only an appropriately analyzed control group can determine whether HLX79 contributes an incremental effect.
What safety findings have emerged from the initial study?
The publicly available ACR abstract describes treatment-emergent adverse events as predominantly Grade 1 or Grade 2. It reports no Grade 3 or higher events assessed as related to HLX79 and identifies one Grade 3 serious adverse event considered unrelated to either study medicine. These findings provide encouraging preliminary information about tolerability within the small interim population.
However, the study’s primary endpoints concern safety and tolerability, making a complete evaluation particularly important. The overall number of treated patients remains limited, and uncommon immune-related complications may not emerge in small early-stage cohorts. Longer treatment and follow-up may also reveal effects not apparent during the initial assessment.
Palleon’s earlier Phase 1 study involved patients with advanced cancers and demonstrated treatment exposure up to 30 mg/kg without reported dose-limiting toxicity. The company also described biological effects involving immune-cell desialylation at higher doses. These results provided a rationale for investigating the medicine in autoimmune disease.
Nevertheless, patients with cancer can differ substantially from those with chronic kidney disorders. Immune function, underlying medical conditions and accompanying treatments may influence tolerability. Safety results from oncology studies therefore cannot establish the complete risk profile of the autoimmune combination.
The addition of rituximab creates further considerations because B-cell depletion can affect infection risk and immune responses. The forthcoming presentation should help clarify the distribution of adverse events between treatment groups and whether there are safety differences associated with HLX79.
How does the Henlius partnership support international development?
Palleon and Shanghai Henlius Biotech established their autoimmune disease collaboration in December 2024. Under the agreement, Henlius obtained exclusive rights to E-602 in China, while Palleon retained rights outside the licensed territory. Henlius is responsible for funding and conducting the Chinese clinical development programme involving its rituximab biosimilar, HANLIKANG.
Palleon is eligible for up to $95.3 million in development and commercial milestone payments under the autoimmune collaboration, together with royalties linked to future commercialization in China. These amounts are contingent on specified achievements and do not represent guaranteed current revenue. The agreement provides a financial and operational framework for testing the approach without Palleon independently conducting every aspect of the Chinese programme.
The companies already had an earlier oncology partnership involving bifunctional sialidase therapies. The autoimmune agreement extended their work into another application of glycan editing. However, the financial terms and development programmes are separate and should not be combined as though they represent one transaction.
For Palleon, positive results could support development outside China, where it retains commercial rights. Such expansion would still require appropriate clinical studies, regulatory engagement and financing. The current Phase 2 response findings do not establish that an international registration programme is already underway.
What should investors and clinicians watch at ASN and ACR 2026?
The first forthcoming presentation is scheduled for October 23 at ASN Kidney Week in Denver. ACR Convergence will follow in Orlando, with the November 11 oral session focused on membranous nephropathy results from the Phase 2 trial. The two meetings provide opportunities to examine additional details of a programme that has already disclosed encouraging preliminary findings.
The published abstracts contain somewhat different interim response summaries, reflecting evolving analyses and potentially different data cutoffs. The ACR abstract reports 17 complete or partial responses among 26 patients, whereas an earlier ASN abstract reported 14 partial responses among 26. The distinction makes it important to identify each dataset’s assessment timing and outcome definition rather than treating the figures as directly interchangeable.
The most consequential information will concern the unblinded comparison between HLX79 plus rituximab and rituximab with placebo. Investigators will also need to examine whether higher doses consistently improve proteinuria and whether biomarker findings support the intended mechanism. Safety outcomes and response durability will influence whether larger development is justified.
Palleon’s latest announcement highlights the emergence of glycan editing as a potential new approach to autoimmune kidney disease. The early results provide a reason for further investigation, particularly because rapid remission could be clinically valuable in patients experiencing substantial protein loss. However, the decisive question remains whether the enzyme adds measurable benefit to an already effective B-cell-directed treatment.
Until the randomized results are fully unblinded, HLX79 should be regarded as an investigational therapy with encouraging preliminary activity rather than a demonstrated improvement over rituximab alone.
