Hansa Biopharma’s Idefirix Achieves 90% One-Year Graft Failure-Free Survival in Kidney Transplant Study

Hansa Biopharma's Idefirix PAES Shows 90% One-Year Graft Survival

Hansa Biopharma announced positive results from its open-label, European 20-HMedIdeS-19 post-authorisation efficacy study (PAES) (NCT05369975) for Idefirix (imlifidase). The study, involving 51 highly sensitised patients undergoing HLA-incompatible kidney transplantation, demonstrated a 90% one-year graft failure-free survival, meeting its primary endpoint. Secondary endpoints also showed strong outcomes, with 92% graft survival and 98% patient survival, alongside a consistent safety profile. These results support Hansa's plan to apply to the European Medicines Agency (EMA) for full marketing authorisation, converting Idefirix's current conditional approval.

• The 20-HMedIdeS-19 PAES confirmed Idefirix's clinical benefit, achieving a 90% one-year graft failure-free survival in highly sensitised patients receiving HLA-incompatible kidney transplants. Key secondary endpoints included a 92% graft survival rate and a 98% patient survival rate one year post-transplantation, with an estimated glomerular filtration rate (eGFR) of 52.4mL/min/1.73m².
• These robust results are crucial for Hansa Biopharma's regulatory strategy, as they will be used to support an application to the European Medicines Agency (EMA) for full marketing authorisation of Idefirix, transitioning from its current conditional approval. The drug's safety profile was consistent with prior clinical trial experience, indicating good tolerability among patients.
• Beyond its primary use in kidney transplantation, Idefirix has shown potential as a pre-treatment in gene therapy, reducing IgG antibodies to enable eligibility for treatment, as demonstrated in a Phase I study with Sarepta Biosciences and Roche’s Elevidys. Separately, Hansa submitted a Biologics License Application (BLA) to the US FDA in February 2026, with a PDUFA target action date of December 19, 2026.

Idefirix's PAES Confirms Clinical Benefit for Kidney Transplants

Recent studies have demonstrated several innovative approaches for managing highly sensitized patients requiring HLA-incompatible kidney transplantation. A 2026 case report detailed the successful use of combination B-cell maturation antigen (BCMA)-targeted T-cell engager therapy in a 37-year-old woman with extreme HLA sensitization (cPRA over 99.9%) who had been waitlisted for 20 years without a suitable transplant offer. The intervention combined obinutuzumab (type II humanized anti-CD20 antibody) with elranatamab (BCMA-targeted T-cell engager), resulting in profound reduction of anti-HLA antibodies from 99.96% to 0% cPRA within six months. Safety outcomes were favorable, with only transient, asymptomatic cytokine release syndrome and self-limited sapovirus-induced diarrhea, while the patient achieved successful transplantation and remained rejection-free with excellent graft function at ten months post-transplant.

A comprehensive 2025 immunoadsorption study evaluated 49 highly sensitized patients (cPRA >85%) undergoing HLA-incompatible kidney transplantation, comparing outcomes with 160 HLA-compatible recipients. The desensitization protocol included immunoadsorption sessions, rituximab, tacrolimus, steroids, and mycophenolate mofetil, followed by antithymocyte globulin induction. Over a mean follow-up of 7.4 years, patient and death-censored graft survival rates were similar between HLA-compatible and HLA-incompatible groups, though HLA-incompatible patients experienced significantly more biopsy-proven rejections, predominantly antibody-mediated. Infectious complication rates remained comparable between groups, demonstrating that immunoadsorption-based desensitization protocols can achieve favorable long-term outcomes in this challenging population.

Novel rescue therapies have also shown promise in refractory cases. A 2025 case series described three patients with refractory early active antibody-mediated rejection who failed standard plasmapheresis and IVIG therapy, but responded to low-dose repetitive splenic irradiation (50cGy per session for 10 sessions). All patients demonstrated continuous decline in donor-specific antibody levels with recovery of renal function, and during 14-75 months of follow-up, two patients achieved negative DSA status while maintaining stable graft function. These findings collectively illustrate the expanding therapeutic arsenal for highly sensitized patients, though they emphasize the need for individualized approaches and careful monitoring of both immunologic and infectious risks.

Addressing Critical Gaps in HLA-Incompatible Kidney Transplants

HLA-incompatible kidney transplantation faces substantial clinical and operational challenges that limit therapeutic success in highly sensitized patients. Current treatment approaches are constrained by inadequate long-term antibody reduction strategies, prolonged wait times, and increased risks of adverse outcomes. These limitations significantly impact patient access to transplantation and post-transplant graft survival.

• Limited therapeutic effectiveness: Current treatments targeting HLA antibodies lack long-term effectiveness, with no existing therapies proven to remove or reduce HLA antibodies effectively in the majority of patients

• Prolonged waiting times and reduced access: Highly sensitized patients experience significantly longer wait times proportional to their sensitization breadth, with some patients never receiving organ offers due to rare HLA phenotypes incompatible with donor populations

• Increased rejection and readmission risks: HLA-incompatible transplants demonstrate higher incidence of early hospital readmission (26.6%) and 2.26-fold increased risk compared to compatible transplants, with patients showing 1.5-fold and 3-fold greater risks of late readmission and death-censored graft loss respectively

• Desensitization protocol limitations: Current protocols using plasmapheresis, IVIG, and rituximab do not eliminate donor-specific B cell clones, leaving patients vulnerable to antibody rebound during pro-inflammatory events and requiring ongoing intensive monitoring

• Technological and diagnostic constraints: HLA typing methodologies yield ambiguous results requiring extensive laboratory resources, while current antibody detection methods are time-consuming and require extensive reagents, limiting rapid clinical decision-making

• Implementation barriers: Molecular matching integration faces logistical, financial, and technological obstacles, including concerns about decreased access for marginalized populations and the need for specialized staffing, funding, and stakeholder education

Beyond Kidney Transplants: Idefirix's Expanding Potential

Imlifidase is being evaluated across several autoimmune and transplant-related conditions beyond its approved indication for HLA-incompatible kidney transplantation. Clinical trials have been conducted for anti-glomerular basement membrane disease through the GOOD-IDES-01 trial, which treated 15 patients with imlifidase and demonstrated complete IgG cleavage within hours. In this open-label study with prospective sample collection over 6 months, plasmapheresis was restarted if anti-GBM antibodies rebounded, which occurred in 10 patients who subsequently showed lower estimated glomerular filtration rates compared to those without rebound.

A randomized, open-label, multicenter trial has evaluated imlifidase for antibody-mediated rejection in kidney transplantation, comparing it directly to plasma exchange across 14 transplant centers. This study randomized 30 patients and achieved its primary endpoint of superior donor-specific antibody reduction with imlifidase (97% versus 42% for plasma exchange), though clinical outcomes showed slightly higher graft survival in the plasma exchange arm. Additional clinical investigation includes a case report of imlifidase treatment in lupus nephritis with end-stage kidney disease, where anti-SSA 60 kDa and anti-SSB autoantibodies decreased by 96% within 36 hours of treatment.

Preclinical research has explored imlifidase applications in immune thrombocytopenia through a novel targeted approach using a recombinant protein conjugate (scIV.3-IdeS) that specifically targets FcγRIIA receptors on platelets. This intervention model demonstrated reduced antiplatelet IgG binding and decreased platelet phagocytosis in vitro, with improved platelet survival in murine models of immune thrombocytopenia. While these studies show promising mechanistic effects, the clinical translation remains limited by imlifidase's immunogenicity and the profound hypogammaglobulinemia it induces.

Idefirix Secures Full Approval, Bolstering Desensitization Strategies

Hansa Biopharma's successful 20-HMedIdeS-19 study, demonstrating a 90% one-year graft failure-free survival for Idefirix, represents a pivotal moment for highly sensitized patients awaiting kidney transplantation. This robust data paves the way for full marketing authorization in Europe, moving beyond its current conditional approval and solidifying imlifidase's role as a critical desensitization agent. For patients with high calculated panel-reactive antibody (cPRA) levels, who often endure prolonged waiting times and limited access to compatible organs, imlifidase offers a rapid and effective solution by cleaving donor-specific antibodies (DSA) and enabling transplantation across significant immunological barriers.

The strategic implications are clear:

• Full marketing authorization will significantly strengthen Idefirix's market position and facilitate broader clinical adoption, particularly for highly sensitized patients who face severe barriers to kidney transplantation.

• The known phenomenon of donor-specific antibody rebound post-imlifidase necessitates strategic development of combination therapies, potentially involving agents targeting B-memory cells and plasma cells, to ensure durable desensitization and long-term graft survival.

• Imlifidase's rapid and extensive IgG cleavage provides a distinct competitive advantage over conventional desensitization methods, positioning it as a preferred option for urgent or challenging HLA-incompatible kidney transplant cases.

However, the journey is not without considerations. While imlifidase excels in pre-transplant desensitization, a randomized trial indicated it did not demonstrate a clinical benefit in improving graft survival when used to treat established antibody-mediated rejection (AMR), suggesting a more defined role in the transplant pathway. Furthermore, the prevalence of anti-IdeS antibodies in the general population, including a small percentage with neutralizing activity, introduces a potential risk of reduced efficacy in some patients, highlighting the need for further assessment and potentially personalized treatment approaches. Despite these considerations, the encouraging five-year follow-up data, showing excellent patient and graft survival, underscores imlifidase's transformative potential. Its integration into international guidelines further cements its importance, promising improved access and outcomes for immunologically disadvantaged patients.