Event-free survival 0.557 on ravulizumab and 0.475 on placebo in transplant-associated TMA
In the Phase 3 trial, with 64 participants analyzed on ravulizumab and 62 on placebo, the event-free survival proportion at Week 26 was 0.557 on ravulizumab and 0.475 on placebo, with a p-value of 0.6386. Alexion's full results for this HSCT-TMA study are now public.
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In a Phase 3 trial of ravulizumab in thrombotic microangiopathy (TMA) after hematopoietic stem cell transplant (HSCT), the proportion of participants with event-free survival during the 26-week treatment period was 0.557 on ravulizumab and 0.475 on placebo, the registry record shows. The sponsor, Alexion Pharmaceuticals, Inc., posted the results on November 4, 2026. The record now gives transplant centers and sponsors the full set of measures from 148 enrolled participants, including a p-value of 0.6386 for the primary outcome comparison.
| Measure | Ravulizumab | Placebo |
|---|---|---|
| Event-free survival during the 26-week treatment period | 0.557 (95% confidence interval 0.427 to 0.669) | 0.475 (95% confidence interval 0.343 to 0.595) |
| TMA response during the 26-week treatment period | 18.8 percent (95% confidence interval 10.1 to 30.5) | 14.5 percent (95% confidence interval 6.9 to 25.8) |
| Hematologic response | 25.0 percent (95% confidence interval 15.0 to 37.4) | 17.7 percent (95% confidence interval 9.2 to 29.5) |
| Overall survival at Week 52 | 0.458 (95% confidence interval 0.332 to 0.576) | 0.453 (95% confidence interval 0.322 to 0.575) |
| Non-relapse mortality at Week 52 | 0.509 (95% confidence interval 0.378 to 0.626) | 0.407 (95% confidence interval 0.280 to 0.531) |
| Deaths from any cause | 27 of 63 participants | 31 of 62 participants |
From the trial registry record NCT04543591, results first posted November 4, 2026.
Why it matters
The Ultomiris label on DailyMed, version published Nov 04, 2026, lists ravulizumab for paroxysmal nocturnal hemoglobinuria, atypical hemolytic uremic syndrome "to inhibit complement-mediated thrombotic microangiopathy (TMA)", generalized myasthenia gravis, neuromyelitis optica spectrum disorder and immunoglobulin A nephropathy. The record's own summary says the study was designed to evaluate the efficacy, safety, pharmacokinetics and pharmacodynamics of ravulizumab in adult and adolescent participants with HSCT-TMA.
Primary outcome
Results were first posted on November 4, 2026. The primary outcome was the proportion of participants with event-free survival during the 26-week treatment period in Stage 2, measured in the full analysis set of all participants randomized in Stage 2.
- Ravulizumab (64 participants): 0.557 (95% confidence interval 0.427 to 0.669).
- Placebo (62 participants): 0.475 (95% confidence interval 0.343 to 0.595).
- Hazard ratio: 0.879 (95% confidence interval 0.526 to 1.467), from a Cox proportional-hazards model with treatment, acute GVHD status and geographic region.
- The p-value was 0.6386, from a stratified log-rank test with stratification by acute graft versus host disease (GVHD) status and geographic region.
The record defines event-free survival as the time from randomization until the first of 2 events: death due to any cause, and clinical worsening up through Week 26. Clinical worsening meant meeting 2 or more criteria: doubling of serum creatinine from baseline or a new requirement of dialysis; an increase in lactate dehydrogenase (LDH) above 25% compared to baseline; a reduction in platelets of more than 25% compared to baseline; a reduction in hemoglobin of more than 10% compared to baseline; increased requirement for platelets or red blood cells at any time. The criteria had to be confirmed by 2 independent samples collected at least 8 hours apart.
Secondary measures
The record lists these Stage 2 secondary measures for ravulizumab and placebo.
- Percentage of participants with TMA response during the 26-week treatment period: 18.8 (95% confidence interval 10.1 to 30.5) on ravulizumab and 14.5 (95% confidence interval 6.9 to 25.8) on placebo.
- Percentage of participants with hematologic response: 25.0 (95% confidence interval 15.0 to 37.4) on ravulizumab and 17.7 (95% confidence interval 9.2 to 29.5) on placebo.
- Overall survival at Week 52: 0.458 (95% confidence interval 0.332 to 0.576) on ravulizumab and 0.453 (95% confidence interval 0.322 to 0.575) on placebo.
- Non-relapse mortality at Week 52: 0.509 (95% confidence interval 0.378 to 0.626) on ravulizumab and 0.407 (95% confidence interval 0.280 to 0.531) on placebo.
The record's TMA response definition has a hematologic response and a renal response. The hematologic response requires a platelet count above 50000 per cubic millimeter without platelet transfusion support during the prior 7 days when the baseline count was 50000 or lower, or a platelet increase of at least 50% from baseline when it was higher, plus normalization of LDH and absence of schistocytes. The renal response requires at least a 50% reduction of proteinuria from baseline.
Study design and size
The trial, ALXN1210-TMA-313, was randomized, double-blind and placebo-controlled, with a start date of December 10, 2020 and a primary completion date of September 19, 2025, both listed as actual. In Stage 1, 20 participants received open-label ravulizumab plus best supportive care to confirm the dosing regimen. In Stage 2, participants were randomized to blinded ravulizumab plus best supportive care or matching placebo plus best supportive care. The treatment period was 26 weeks, followed by a 26-week follow-up period. Weight-based doses of ravulizumab were given intravenously as a loading dose followed by maintenance dosing every 8 weeks.
Safety and deaths
The record's adverse event tables cover Day 1 through Week 52 in the safety set of participants who received at least 1 dose of study drug. During the Stage 2 treatment period, 52 of 63 participants on ravulizumab and 44 of 62 on placebo had a serious adverse event. Deaths from any cause were 27 of 63 participants on ravulizumab and 31 of 62 on placebo. Ten participants on placebo who met criteria for clinical worsening after Day 15 received ravulizumab as rescue treatment.