Ianalumab Enhances Treatment Outcomes in Immune Thrombocytopenia Patients

Patients with immune thrombocytopenia (ITP) who received the investigational drug ianalumab alongside standard therapy experienced significantly longer periods without treatment failure compared to those given a placebo. This important finding emerged from a study presented at the 67th American Society of Hematology (ASH) Annual Meeting and published in the journal Blood.

The research marks a significant advancement as it is the first trial to evaluate a novel medication for ITP early in the disease progression. According to the lead study author, Hanny Al-Samkari, MD, who holds the Peggy S. Blitz Endowed Chair in Hematology/Oncology at the Mass General Brigham Cancer Institute and serves as an associate professor of medicine at Harvard Medical School, the addition of ianalumab provided long-term disease control without necessitating chronic therapy or increasing infection risk.

ITP is an autoimmune disorder in which the immune system erroneously destroys platelets, which are essential for blood clotting. A normal platelet count ranges from 150,000 to 400,000 per microliter, while patients with ITP often have counts below 50,000. Approximately 50,000 individuals in the United States are affected by this rare condition, with women being more frequently diagnosed than men. Standard first-line treatments typically involve steroids, which can lead to adverse effects such as obesity, cataracts, and reduced bone density.

Dr. Al-Samkari emphasized the challenges of treating patients with ITP over time, stating, “The longer people have ITP, the more difficult it becomes to treat. One of the major unmet needs in ITP treatment is a therapy that truly changes the course of the disease.”

Ianalumab works by targeting B cells, which are white blood cells that contribute to the immune response. By inhibiting signals necessary for B cell activation and growth, the drug helps eliminate the overactive cells while preventing the formation of new ones.

The VAYHIT2 trial, a Phase III randomized controlled study, involved 152 patients from the United States and 23 other countries who had either not responded to or relapsed after standard first-line treatments. Approximately two-thirds of participants were women, and all had platelet counts below 30,000 upon entering the study.

Patients received eltrombopag, a once-daily oral medication approved by the U.S. Food and Drug Administration, for 16 to 24 weeks, which stimulates the bone marrow to increase platelet production. In addition to this treatment, participants were randomly assigned to receive either four once-monthly infusions of a lower dose of ianalumab (3 mg/kg), a higher dose (9 mg/kg), or a placebo.

The primary endpoint of the study was the time to treatment failure, defined as the time until patients experienced a bleeding event that required “rescue therapy” or a new treatment for ITP after discontinuation of the study therapy. The secondary endpoint assessed stable response at six months, defined by maintaining platelet counts above 50,000 without requiring rescue therapy.

Results showed that patients on the higher dose of ianalumab had a median time to treatment failure of 13 months, while those on the lower dose had “not estimable” results due to a small number of events. In contrast, the placebo group had a time to treatment failure of 4.7 months.

At the six-month mark, 62% of patients on the higher dose of ianalumab and 56.9% of those on the lower dose achieved a stable response, compared to 39.2% in the placebo group. Additionally, both ianalumab groups reported lower fatigue levels—an important symptom of ITP—on quality of life assessments compared to the placebo group.

While patients treated with ianalumab experienced higher rates of transient neutropenia, a condition characterized by low levels of neutrophils, this side effect typically resolved within a few days. Importantly, the rate of infections among ianalumab recipients was not higher than that of the placebo group, nor were the infections more severe.

One limitation of the study is that all enrolled patients had only received one prior treatment for ITP, leaving unclear whether ianalumab would be effective for those with multiple previous therapies. Furthermore, the follow-up period was not sufficiently long to determine if ianalumab could halt long-term disease progression.

Dr. Al-Samkari noted, “We will follow the patients for 39 months to look at the long-term durability of ianalumab treatment.” A subsequent trial, VAYHIT1, is currently underway to evaluate the efficacy of ianalumab combined with steroids or placebo in previously untreated patients with ITP. This study will also be published in The New England Journal of Medicine.

More information can be found in the study “Primary results from VAYHIT2, a randomized, double-blind, phase 3 trial of ianalumab plus eltrombopag versus placebo plus eltrombopag in patients with primary immune thrombocytopenia (ITP) who failed first-line corticosteroid treatment,” available in Blood (2025). DOI: 10.1182/blood-2025-lba-2.