Rilzabrutinib Shows Promising Long-Term Benefits for ITP Patients

Rilzabrutinib has demonstrated sustained platelet responses and improved symptoms in patients with immune thrombocytopenia (ITP) according to long-term extension data from the LUNA 3 trial. Presented by David Kuter, MD, director of clinical hematology at Massachusetts General Hospital and professor of medicine at Harvard Medical School, these findings highlight the potential of rilzabrutinib to enable patients to reduce their reliance on corticosteroids.

The results were shared at the 67th American Society of Hematology (ASH) Annual Meeting and Exposition. Kuter emphasized the significance of the long-term extension study, stating, “The major outcome is that patients were able to wean off or down on their concurrent ITP therapies,” which primarily included corticosteroids and thrombopoietin receptor agonists. More than half of the patients in the study either discontinued or reduced these medications.

Overview of the LUNA 3 Trial

The LUNA 3 trial was a randomized, double-blind study conducted at 155 sites globally. Enrollment criteria required participants to be aged 12 years or older and have primary ITP lasting more than six months. Patients also needed to have platelet counts averaging ≥35,000/μL and hemoglobin levels exceeding 9 g/dL prior to the first dose.

During the initial 24-week treatment period, patients were randomly assigned to receive either rilzabrutinib 400 mg or a matching placebo twice daily. The primary outcome measured was durable platelet response over the final six weeks of treatment. Secondary outcomes included the number of weeks with platelet counts ≥50,000/μL, the proportion of patients requiring rescue therapy, and overall stability of platelet responses during the trial.

After completing the initial phase of LUNA 3, patients who achieved a defined response during the last eight weeks were eligible to participate in the extension study, which involved continued treatment with oral rilzabrutinib until a loss of response occurred on two consecutive visits or for safety reasons.

Key Findings and Patient Impact

As of April 1, 2025, a total of 169 patients had enrolled in the extension study. The median age of participants was 52 years, with a range from 18 to 80 years. Among those, 72% were female, and the median duration of ITP was 9.6 years.

At the outset, the median platelet count of participants was 18 x 10^9/L. Follow-up visits showed that platelet counts increased significantly, ranging from 83 to 168 x 10^9/L over the 33 months of the extension study. During the first year, patients maintained platelet counts of ≥50 x 10^9/L or between 30-50 x 10^9/L in an average of 88% of visits.

For those receiving rilzabrutinib monotherapy or in conjunction with corticosteroids, median platelet counts at entry were 78 x 10^9/L and 115 x 10^9/L, respectively. These counts remained stable, ranging up to 270 x 10^9/L and 160 x 10^9/L throughout the study period.

Among the 34 patients who had been on concurrent corticosteroids, ten discontinued their use, while two reduced their dosage by at least 50%. The median platelet counts before and after corticosteroid cessation were 148 x 10^9/L and 178 x 10^9/L, respectively.

In addition to these findings, Sanofi has shared data from the LUMINA series of trials, which is also investigating rilzabrutinib in warm autoimmune hemolytic anemia. The company has plans for broader investigations into various autoimmune conditions, with Kuter noting the relevance of ITP as a model for therapy in these diseases.

The results from the LUNA 3 trial extension provide significant insights into the long-term benefits of rilzabrutinib for patients with ITP, potentially transforming treatment protocols and improving quality of life.