Biogen (NASDAQ:BIIB) outlined its growing “West Coast Hub” and development plans for felzartamab, an anti-CD38 antibody being studied across multiple kidney-related immunology indications, during a conference discussion between Leerink Partners analyst Marc Goodman and Utpal Patel, Biogen’s Head of the West Coast Hub.
West Coast Hub built around HI-Bio acquisition and felzartamab
Patel, a nephrologist by training, said he joined Human Immunology Biosciences (HI-Bio) to help develop new treatments for kidney disease. HI-Bio had licensed felzartamab from MorphoSys, and early proof-of-concept studies in three indications “read out positively,” prompting plans to advance the program into Phase 3.
Antibody-mediated rejection (AMR) positioned as lead indication
Patel identified antibody-mediated rejection (AMR) in kidney transplant recipients as the lead felzartamab indication, driven by what he described as “compelling results” in a Phase 2 proof-of-concept study and an earlier expected data readout versus other programs. He said AMR is a leading cause of late kidney transplant loss and that once patients develop it, “over 75% will lose their grafts” within a few years, with a median time to graft failure of about two years.
Patel described an investigator-initiated European trial in 22 patients, randomized 1:1 to felzartamab or control, using a nine-dose regimen over five months. The primary endpoint was biopsy-based histology at six months, assessed using Banff classification criteria, including the microvascular inflammation (MVI) score. Patel said the study showed “dramatic reversal” of AMR by histology, with over 80% showing reversal and more than two-thirds of treated participants reaching an MVI score of zero—an outcome he said had not previously been seen in the field.
Biogen’s Phase 3 AMR study is designed as a 120-patient global trial, primarily enrolling in Europe, North America, South America, Australia, and New Zealand. Patients are randomized to felzartamab or placebo, with biopsies required for inclusion. The primary endpoint is at six months, with follow-up to one year. Patel said that because AMR activity returned in Phase 2 after therapy stopped, the Phase 3 design continues dosing into the second six months for patients originally assigned to felzartamab. Patients on placebo will cross over to active therapy at six months, which Patel said was intended to reduce dropouts and support trial completion.
Patel said the study is enrolling well and that Biogen expects a primary topline readout next year. He also said the program has Breakthrough Therapy designation and Orphan designation in the U.S.
Market sizing and competition discussed for AMR
On the potential market, Patel said the U.S. has more than 300,000 people living with a kidney transplant, with around 23,000 people having AMR. He estimated that approximately 11,000 U.S. patients meet the trial’s criteria (including being at least six months post-transplant and donor-specific antibody positive). Patel described that number as growing, citing more than 100,000 people on the U.S. kidney transplant wait list and the survival difference between dialysis and transplantation.
Patel said there are no approved therapies for AMR and described current practice as focused on removing antibodies through plasmapheresis or interfering with antibody activity using intravenous immunoglobulin, which he said are not effective at reversing AMR. He characterized competing pipeline approaches as complement-focused therapies (including C1s inhibition), which he described as downstream from the disease mechanism. In contrast, Patel said targeted CD38 therapy depletes antibody-producing cells and also removes natural killer (NK) cells that express CD38, which he said are drivers of the disease and were highlighted through Biogen’s studies.
On pricing, Patel said Biogen had not provided details, but the discussion referenced IgA nephropathy (IgAN) pricing as an analog for rare kidney disease therapies.
Additional programs: MVI, IgAN, and primary membranous nephropathy
Patel also discussed microvascular inflammation (MVI) as a newer recognized entity in transplant patients who are donor-specific antibody negative. He cited an epidemiologic study published in late 2024 in The New England Journal of Medicine evaluating international registries and said patients with MVI can have graft loss rates “almost as bad” as donor-specific antibody-positive AMR under updated Banff 2022 criteria. Patel estimated the U.S. MVI population at about 5,000 patients and said Biogen has started a Phase 2 study with 81 patients, enrolling at the same centers as the AMR Phase 3 trial, with the first participant enrolled “this month.” He said the study could potentially be registration-enabling.
For IgA nephropathy, Patel described Phase 2 results from the IGNAZ study: 54 participants across four dosing arms plus an additional Japanese cohort. Dosing arms included placebo and regimens of two doses over two weeks, five doses over two months, and nine doses over five months. Patel said the nine-dose course produced a roughly 50% placebo-adjusted reduction in proteinuria, with durability observed out to two years off treatment in non-Japanese participants (the Japanese cohort was followed to one year). He also said the safety profile showed modest IgG decreases that returned to normal a few months after dosing and noted that participants mounted a normal immune response to COVID vaccination during the trial period.
Patel described IgAN’s competitive landscape in three broad “buckets”: foundational chronic kidney disease therapies that reduce decline but are not disease-modifying, complement-focused anti-inflammatory therapies, and potentially disease-modifying approaches such as APRIL-pathway agents and CD38 therapies. He said APRIL-pathway agents require chronic dosing, with markers such as proteinuria returning within three to four months after stopping therapy. Biogen’s IgAN Phase 3 study is underway globally, using a 1:1 randomization to a nine-dose felzartamab regimen or placebo, with follow-up to two years and a nine-month interim analysis based on proteinuria. Patel said the program includes a small subcohort with lower kidney function (GFR 20–30).
For primary membranous nephropathy (PMN), Patel said felzartamab’s nine-dose regimen rapidly depleted the PLA2R autoantibody in Phase 1/2 studies in high-risk patients and that effects deepened beyond the treatment interval, though some patients had return of the autoantibody near one year. Biogen’s Phase 3 PMN trial includes 180 participants randomized to felzartamab or tacrolimus. Patients on felzartamab receive the nine-dose course at the start of year one and again at the start of year two, with complete remission at two years as the approvable endpoint. Patel said there are no approved PMN therapies and outlined current options clinicians cycle through, including anti-CD20 therapies (with noted non-response and relapse rates), tacrolimus (limited by potential kidney injury with prolonged use), and cyclophosphamide (effective but potentially toxic). He estimated the U.S. PMN population at about 36,000, and said IgAN prevalence estimates are at least 130,000 in the U.S.
Pipeline expansion and commercialization approach
Looking ahead, Patel said Biogen is working to develop a subcutaneous formulation of felzartamab to improve convenience and is also pursuing a next-generation anti-CD38 to expand beyond the initial indications. He said clinicians have used available anti-CD38 therapies off-label in difficult autoimmune diseases, providing a roadmap for additional opportunities. Patel said Biogen plans to start two additional proof-of-concept studies this year in other indications but did not specify which ones.
On commercialization, Patel argued that initial focus could be manageable due to care concentration at major centers. He said there are roughly 250 transplant centers in the U.S., but “north of 80%” of transplant patients are followed at 50 to 100 centers. He added that many of these specialized centers also treat complex glomerular diseases such as IgAN and PMN. Patel estimated there are about 10,000 nephrologists in the U.S., with around 5,000 actively treating glomerular disease, and he said the field is moving toward “centers of excellence” as more therapies enter development.
About Biogen (NASDAQ:BIIB)
Biogen Inc is a multinational biotechnology company focused on discovering, developing and delivering therapies for neurological and neurodegenerative diseases. Headquartered in Cambridge, Massachusetts, the company has a longstanding emphasis on neuroscience, with research and commercial activities spanning multiple therapeutic areas including multiple sclerosis, spinal muscular atrophy and Alzheimer’s disease. Biogen was founded in 1978 and has grown into a global biopharmaceutical firm with operations and commercial presence across North America, Europe, Japan and other international markets.
The company’s marketed portfolio has historically included several well-known therapies for multiple sclerosis such as Avonex, Tysabri and Tecfidera, and it has pursued treatments for rare neurological conditions and genetic neuromuscular disorders.
