Investigational treatment for primary immune thrombocytopenia shows promise in trial

An experimental monoclonal antibody called ianalumab had promising results for more than half of patients with primary immune thrombocytopenia enrolled in a phase 3 trial, according to data published in the New England Journal of Medicine.

The research, titled “Ianalumab plus Eltrombopag versus Placebo plus Eltrombopag in Immune Thrombocytopenia,” was also presented at the 67^th American Society of Hematology Annual Meeting and Exposition held this week in Orlando.

“As a hematologist, I’m glad that we have effective therapies for ITP, but they’re not necessarily ideal for chronic disease management or long-term quality of life,” Adam Cuker, M.D., MS, section chief for hematology, clinical director of the Penn Blood Disorders Center and lead author, said in a news release. “This study shows that prolonged, durable responses to ITP treatment, without the need for ongoing therapy, are possible—and that’s a huge advantage for patients.”

Primary immune thrombocytopenia (ITP) is a rare autoimmune condition that affects approximately 50,000 people in the United States and can be diagnosed at any age. It is characterized by severe bleeding episodes, associated with skin and mucous membranes, caused by immune cells that mistakenly attack platelets, which are the blood cells responsible for clotting. Symptoms include bleeding gums, nosebleeds, heavy menstruation, fatigue and easy bruising.

Not all patients with ITP require treatment, but for patients with recurrent bleeding episodes, ITP can be deadly. There are currently three FDA-approved second-line therapies for ITP, but all generally require lifelong use, given as weekly injections or a daily pill.

ITP is caused by autoreactive B-cells, which produce anti-platelet antibodies. Ianalumab targets the B-cell-activating factor (BAFF) receptor, which depletes these cells.

Cuker and his team recruited 152 adult patients with ITP and separated them into three arms: high-dose ianalumab, low-dose ianalumab, and placebo. Patients were given ianalumab intravenously once a month for four months alongside eltrombopag, a pill currently approved for long-term treatment, because ianalumab takes time to start working. Eltrombopag was tapered off and stopped.

Success was measured using “time to treatment failure,” which was defined as a low platelet count, the need for additional ITP therapy, the inability to discontinue eltrombopag or death.

Results showed that 54% of patients given high doses of ianalumab had an estimated probability of avoiding treatment failure for 12 months, compared with 51% of patients in the low-dose arm and 30% of patients given placebo.

Platelet counts were measured at six months, which was two months after the final ianalumab dose. Most patients in the high-dose arm (62%) had stable platelet counts compared with only 40% of patients given placebo.

“We’re looking forward to seeing if the treatment-free responses in this study extend out even further,” Cuker said. “Improving the long-term reality of living with ITP is not something we’ve been able to think about before. The goal has always been to improve platelet counts or reduce the risk of bleeding, but this research is ushering in a new era of hope for patients with ITP.”