AstraZeneca's Ultomiris Shows Promise in Rare Post-Transplant Complication

AstraZeneca has unveiled encouraging early results from a phase 3 trial of Ultomiris (ravulizumab) in pediatric patients with thrombotic microangiopathy (TMA) following hematopoietic stem cell transplantation (HSCT). The data, presented at the 2025 European Hematology Association meeting in Milan, Italy, highlights the potential of Ultomiris to address a life-threatening complication that currently lacks targeted treatment options.

Impressive Survival Rates in Pediatric HSCT-TMA Patients

The ALXN1210-TMA-314 study, involving 41 pediatric patients aged 28 days to under 18 years, demonstrated an overall survival rate of 87.2% at 26 weeks. This marks a significant improvement over historical survival rates, which have been estimated to be as low as 18% in children with HSCT-TMA.

While only 17.1% of patients achieved the primary endpoint of complete TMA response at 26 weeks, AstraZeneca reported that 71% of patients met at least one TMA response criterion. Notably, 58.5% and 53.7% of patients met predefined response criteria for platelet count and urine protein-to-creatine ratio, respectively.

Potential Game-Changer for Post-Transplant Complications

HSCT-TMA is a rare and potentially fatal complication that can occur after stem cell transplant procedures for cancer and other diseases. It causes clotting and damage to blood vessels, potentially leading to organ failure and death. The condition is particularly challenging to diagnose due to its symptoms overlapping with other post-transplant complications.

Franco Locatelli, M.D., Ph.D., an investigator in the Ultomiris trial, stated, "The response rates and the overall survival observed with ravulizumab may be a practice-changing advancement in this field, providing a potentially effective option for these young patients and their families."

Ultomiris: A Key Asset in AstraZeneca's Rare Disease Portfolio

Ultomiris, which AstraZeneca acquired through its $39 billion purchase of Alexion in 2021, has been a focal point of the company's rare disease strategy. The complement inhibitor has already matched the indications of its predecessor, Soliris, most recently gaining FDA approval for neuromyelitis optica spectrum disorder (NMOSD) in March 2025.

AstraZeneca has communicated blockbuster sales expectations for Ultomiris in both HSCT-TMA and cardiac surgery-associated acute kidney injury, pending approval in these indications. The drug has shown strong commercial performance, with sales growing approximately 32% to $3.9 billion in 2024.

As AstraZeneca continues to expand Ultomiris' reach, the company is also conducting midphase trials for the drug in lupus nephritis and immunoglobulin A nephropathy, further solidifying its position in the rare disease market.