Tegoprubart Islet Transplant Signal Is Compelling But Evidence Tier Remains Early-Phase and Uncontrolled

Eledon's Tegoprubart Enables Two Years of Insulin Independence in T1D Patient

Marlaina Goedel, the first patient in a clinical trial, achieved insulin independence for two years following a pancreatic islet cell transplantation using Eledon Pharmaceutical Inc.'s investigational anti-rejection drug, tegoprubart. The procedure, led by Dr. Piotr Witkowski at the University of Chicago Medicine, involved transplanting deceased-donor pancreatic islet cells into the patient's liver. This breakthrough offers a "functional cure" for type 1 diabetes, with Goedel stopping insulin within weeks and maintaining excellent blood sugar control. The trial's success, including 12 patients achieving complete insulin independence with an average HbA1c of 5.4% and no severe hypoglycemic events, highlights tegoprubart's potential as a safer anti-rejection drug.

• Marlaina Goedel's achievement marks a significant milestone, being the first patient to maintain insulin independence for two years after a pancreatic islet cell transplant. The procedure, performed at the University of Chicago Medicine by Dr. Piotr Witkowski, involved transplanting deceased-donor islet cells into the liver, followed by treatment with Eledon's tegoprubart to prevent rejection. This demonstrates the long-term viability and effectiveness of this novel therapeutic approach.
• Eledon Pharmaceutical Inc.'s investigational drug, tegoprubart, is crucial to the trial's success, acting as a safer anti-rejection medication compared to traditional immunosuppressants like tacrolimus, which are toxic to islet cells and kidneys. The drug's ability to protect transplanted cells without causing severe side effects has been a game-changer, allowing patients to maintain insulin independence and excellent glycemic control.
• The initial cohort of 12 patients in the trial all achieved complete insulin independence, maintained an average HbA1c of 5.4%, and experienced no severe hypoglycemic events or drug side effects. This strong data has led Eledon to submit tegoprubart as an Investigational New Drug (IND) to the FDA in September 2026, aiming to advance it to a registrational clinical trial. This could expand eligibility for islet cell transplants beyond patients with life-threatening hypoglycemia, making the therapy accessible to a much broader T1D population.

Tegoprubart's Islet Transplant Trial: Key Efficacy and Safety

Recent clinical research in type 1 diabetes spans a range of interventions — from immunomodulatory therapies and closed-loop insulin delivery to glucagon rescue agents and advanced hybrid systems — each generating distinct efficacy and safety signals relevant to clinical and strategic decision-making.

• CLOuD Study | Hybrid Closed-Loop Insulin Delivery: This open-label, multicentre, randomised parallel trial enrolled 96 participants aged 10–16.9 years within 21 days of T1D diagnosis. The intervention compared hybrid closed-loop (CL) insulin delivery against standard multiple daily injections (MDI) over 24 months. The primary efficacy outcome is the between-group difference in area under the stimulated C-peptide curve (AUC) of the mixed meal tolerance test (MMTT) at 12 months post-diagnosis. Key secondary outcomes include time in target glucose range (3.9–10 mmol/L), HbA1c, and time in hypoglycaemia (<3.9 mmol/L) at 12 months.

• Immunomodulatory Interventions Meta-Analysis | Teplizumab, Otelixizumab, Low-Dose IL-2: This systematic review and meta-analysis of 19 studies (n = 1,852) found that immunotherapy significantly preserved C-peptide (SMD = 0.221, 95% CI: 0.069–0.373, p = 0.007) without improving HbA1c (SMD = 0.033, 95% CI: -0.070–0.136, p = 0.488). Low-dose IL-2 produced a paradoxical profile: marked regulatory T-cell expansion (SMD = 2.23, p = 0.003) and improved HbA1c (SMD = -0.514, p = 0.025) without preserving C-peptide (SMD = 0.020, p = 0.967). WBC clearance agents demonstrated 3.2-fold higher serious adverse event rates than Treg enhancement agents (34.5% vs. 10.8%), with all five reported deaths occurring in the WBC clearance group. Insulin requirement benefits showed significant time-dependent attenuation (R² = 49.06%, p = 0.009).

• Dasiglucagon Integrated Safety and Efficacy Analysis | Dasiglucagon: Pooled data from two placebo-controlled and two non-placebo-controlled trials in adults with T1D evaluated dasiglucagon — a ready-to-use aqueous glucagon analogue — for severe hypoglycaemia rescue. Median time to plasma glucose recovery was 10.0 minutes for dasiglucagon versus 12.0 minutes for reconstituted glucagon and 40.0 minutes for placebo (P < 0.0001). In placebo-controlled datasets, no serious adverse events, withdrawals due to adverse events, or deaths were reported. The most common causally related adverse events were nausea (56.5%) and vomiting (24.6%).

• AWeSoMe Study | Open-Source AID vs. MiniMed™ 780G: This multicentre retrospective study compared glycaemic outcomes in youth with T1D using open-source automated insulin delivery (AID; n = 26) versus the MiniMed™ 780G system (n = 20) over a median of 10.9 months. Both systems similarly reduced HbA1c (~0.3%) and achieved comparable time-in-range (TIR) improvement. However, open-source AID users spent significantly longer time below range: TBR <3.9 mmol/L was 4.2% (IQR 2.6, 7.3) versus 2.0% (IQR 1.0, 4.0) (p = 0.005), and TBR <3.0 mmol/L was 1.1% (IQR 0.4, 2.3) versus 0.0% (IQR 0.0, 1.0) (p = 0.001).

• Older Adults Diabetes Technology Meta-Analysis | Automated Insulin Delivery and CGM: This systematic review and meta-analysis of five RCTs (482 participants; mean age 69.2 years; mean T1D duration 36.1 years) evaluated stepwise advances in diabetes technology. Higher-level technologies significantly increased TIR (MD = +7.90%, 95% CI: 7.09 to 8.72, p <0.001) and reduced TBR <3.9 mmol/L (MD = -0.62%, 95% CI: -1.02 to -0.22, p = 0.002). Severe hypoglycaemia risk was markedly lower with higher-level technologies (Peto OR = 0.16, 95% CI: 0.06 to 0.41, p <0.001; number-needed-to-treat = 20), without a significant increase in DKA risk (Peto OR = 3.72, 95% CI: 0.75 to 18.49, p = 0.11).

Overcoming Immunosuppression Challenges in T1D Islet Transplants

Despite significant advances in insulin therapy, device technology, and emerging immunological approaches, the management of Type 1 Diabetes (T1D) remains constrained by a range of clinical, pharmacological, and safety limitations. No single current strategy fully replicates endogenous insulin physiology or addresses the underlying autoimmune etiology, leaving substantial unmet need across the treatment landscape.

• Suboptimal glycemic control and insulin-associated risks: Intensive insulin therapy — whether via multiple daily injections or continuous subcutaneous insulin infusion (CSII) — is associated with hypoglycemia and weight gain. Complications of T1D remain prevalent due to suboptimal glycemic control despite advances in analogue insulin, its delivery, and glucose monitoring technology.

• Limitations of insulin pump therapy and infusion set failure: CSII is not without hazard. Early morning CSII programming for a fixed increase in insulin delivery to counteract the dawn phenomenon is ineffective and may be hazardous, with hypoglycemia occurring more frequently in CSII programmers (37%) compared to non-programmers (18%) (P=0.001). Infusion set failures — including kinking, occlusion, lipohypertrophy, and dislodgement — occur at an average rate of 4.5 failures/person-year in pediatric populations, with lipohypertrophy specifically associated with worsening metabolic control (P<0.0028).

• DKA risk with adjunctive SGLT inhibitor therapy: While SGLT2 inhibitors such as dapagliflozin, sotagliflozin, and empagliflozin offer glycemic and weight benefits as adjuncts to insulin, they carry a clinically meaningful risk of diabetic ketoacidosis (DKA). In a real-world Saudi cohort, DKA episodes were reported in 10.8% of empagliflozin-treated T1D patients. Emerging safety data have raised questions as to whether the risk of euglycaemic DKA is higher in clinical practice than observed in controlled trials.

• Unapproved status of promising adjunctive agents: GLP-1 receptor agonists (GLP-1 RAs) are associated with improved cardiometabolic profile — including considerable weight loss and reduction in total daily insulin dose — but are currently not approved for the treatment of T1D. Real-world use remains off-label, limiting systematic adoption and post-market safety surveillance.

• Immunotherapy durability and breadth of effect: Teplizumab, the first approved disease-modifying therapy for stage 2 T1D, delays progression to clinically manifest T1D by an average of only 2–3 years. A single administration or short course of immunotherapy is unlikely to provide sustained freedom from exogenous insulin. HbA1c and total insulin dose are less likely to be significantly different between treated and placebo groups, and most successful trials have been conducted in narrow populations with preserved C-peptide.

• Islet transplantation barriers: Transplantation of pancreatic islets holds potential to restore endogenous insulin production, but widespread implementation is constrained by significant limitations, including initial islet loss, engraftment failure, and vulnerability to alloimmunity and autoimmunity. Stem-cell-based β-cell replacement therapies remain under clinical investigation and are not yet broadly available.

Expanding Islet Transplant Access for More T1D Patients

Several intersecting unmet needs define the current T1D landscape. Disease-modifying intervention remains a critical gap: teplizumab, an anti-CD3 monoclonal antibody, has received FDA approval (2022) and European Medicines Agency authorization (2025) specifically to delay progression to stage 3 T1D in adults and children aged 8 years and older diagnosed with stage 2 disease — making it the first approved disease-modifying therapy in this indication. Research is now focused on identifying which endotypes derive the greatest benefit, with clinical evidence suggesting that individuals under 15 years of age, who exhibit the highest immune activity marked by aggressive T-cell infiltration and rapid pancreatic β-cell destruction, experience the most significant delay in disease progression following teplizumab treatment. This underscores early-onset T1D as a priority population for prevention trials and refined screening protocols.

Beta-cell replacement and preservation represent a second major axis of unmet need. Allogeneic islet transplantation, now covered by the French national health insurance system since 2021, remains constrained by donor scarcity, complex isolation procedures, and the requirement for lifelong immunosuppression. Stem cell-derived approaches are advancing rapidly: insulin independence under immunosuppression was achieved at 1 year in 83% of patients after intraportal transplantation of human embryonic stem-cell-derived islets, and stable human C-peptide production was observed 12 months after intra-muscular transplantation of engineered hypoimmune islets without immunosuppression. Residual beta-cell function at diagnosis — measurable through circulating C-peptide — is strongly associated with HbA1c (β=−0.29; 95% CI −0.39, −0.20) and CGM time in range (β=0.41; 95% CI 0.30, 0.52), reinforcing the clinical value of preservation strategies in newly diagnosed patients.

Pediatric populations carry a disproportionate burden of acute and chronic complications that remain inadequately addressed. Diabetic ketoacidosis (DKA) at T1D onset in children from Greater Poland rose from 47.7% in 2006–2014 to 53.4% in 2015–2023 (p=0.007), with severe DKA cases increasing sharply from 15.5% to 27.7% (p<0.001) — a trend driven in part by low healthcare and parental awareness of T1D symptoms. Adolescents and young adults face additional psychosocial and metabolic challenges: disordered eating behaviors were identified in 42.1% of 147 individuals with T1D aged 13–21 years, with distinct risk factor profiles across high and low glycemic variability groups. Diabetic gastroparesis, though rare in pediatric age, represents a further underrecognized complication in adolescents with long-standing, poorly controlled diabetes. Collectively, these data highlight the need for population-specific intervention strategies spanning early diagnosis, disease modification, beta-cell replacement, and psychosocial support.

A Functional Cure for T1D: Islet Transplantation's Next Frontier

The recent announcement regarding Eledon Pharmaceutical Inc.'s tegoprubart in pancreatic islet cell transplantation for type 1 diabetes marks a potentially transformative moment. Achieving two years of insulin independence with excellent glycemic control and no severe hypoglycemic events in a patient, and similar results across a small cohort, suggests a significant leap towards a 'functional cure.' This is particularly impactful given the chronic burden of T1D and the limitations of current therapies for patients with problematic hypoglycemia and glycemic lability.

The core innovation appears to be tegoprubart's role as a safer anti-rejection drug. Existing literature consistently highlights that avoiding the risks of chronic immunosuppression is a critical 'next frontier' in cell replacement therapies. If this safety profile holds, it could dramatically expand the accessibility and appeal of islet transplantation, moving it from a last-resort option for high-risk patients to a more broadly considered treatment.

For Eledon Pharma, this positions them at the forefront of a burgeoning field. The strategic implications are substantial:

• It could establish a new standard of care for islet transplantation, potentially expanding the market beyond its current niche.

• The success validates their anti-rejection platform, suggesting broader applicability for tegoprubart in other transplant indications.

However, the journey towards widespread adoption and sustained success is nuanced, with several critical considerations:

• Long-term Graft Integrity: Studies indicate that even with initial success, transplanted β-cells can lose their end-differentiated phenotype, raising questions about the sustained functional mass and durability of the 'cure' beyond the observed period.

• Persistent Immune Challenges: Despite advanced immunosuppression, the risk of late graft rejection due to breakthrough immune responses, such as B cell infiltration, remains a concern, suggesting ongoing vigilance is required.

• Replicability and Standardization: The literature emphasizes that successful outcomes in islet transplantation are highly dependent on factors like sufficient islet mass and standardized protocols. Ensuring consistent results across diverse patient populations and clinical settings will be crucial.

This early success with tegoprubart offers a compelling vision for the future of T1D treatment. The next steps will involve rigorous, larger-scale trials to confirm these promising results, address long-term durability, and solidify its role in the evolving landscape of cell replacement therapies.