What You Need to Know About the Inrebic Approval for Myelofibrosis

After almost eight years since the last Food and Drug Administration (FDA) action, patients with myelofibrosis now have two approved treatment options available to them.

Last week, the agency approved Inrebic (fedratinib), a JAK-2 inhibitor, to treat adult patients with intermediate-2 or high-risk primary or secondary (post-polycythemia vera or post-essential thrombocythemia) myelofibrosis.

“We at the MPN Research Foundation are thrilled to see more options for people living with myelofibrosis who have long suffered with few options for relief,” Michelle Woehrle, executive director of the foundation, said in an interview with CURE. “We hope the approval of Inrebic ushers in a new era with many more new, safe and effective options for people living with polycythemia vera, essential thrombocythemia and myelofibrosis.”

Myelofibrosis

Myelofibrosis — a type of myeloproliferative neoplasm (MPN) – is a chronic blood cancer where excessive scar tissue forms in the bone marrow, disrupting the body’s normal production of blood cells, which can lead to anemia, weakness, fatigue and enlargement of the spleen and liver, among other symptoms.

The disease can arise on its own or from progression from polycythemia vera or essential thrombocythemia — also two types of MPNs.

Prior to last week’s approval, this patient population had few options for treatment: Jakafi (ruloxitinib) or an allogenic stem cell transplantation (ASCT).

“Because myelofibrosis is a serious and potentially life-threatening malady, we and others are still pursuing research in hopes of finding more therapies and eventually a cure, but in the meantime and in cases where people with myelofibrosis are not necessarily qualified or interested in a stem cell transplant, they are suffering with symptoms which can in some cases be relieved,” Woehrle said.

Inrebic approval

The FDA based its decision on data from the double-blind, randomized, placebo-controlled phase 3 JAKARTA trial — a pivotal study designed to evaluate the efficacy of once-daily doses of Inrebic compared with placebo in 289 patients with intermediate-2 or high-risk myelofibrosis, post-polycythemia vera myelofibrosus or post-essential thrombocythemia myelofibrosis with splenomegaly – an abnormal enlargement of the spleen.

The study demonstrated that patients experienced a 35% or great spleen volume reduction. Of the 96 patients treated with the recommended dose of 400 mg of Inrebic, 35 (37%) achieved a 35% or greater reduction in spleen volume, compared with just one of 96 patients who received placebo in the study.

Moreover, the median duration of time to spleen response for patients in the recommended dosing group was 18.2 months, and 40% experienced a 50% or greater reduction in myelofibrosis-related symptoms compared with only 9% of patients receiving placebo who experienced a decline in these symptoms.

The most common side effects associated with Inrebic were diarrhea, nausea, anemia and vomiting.

Moving Forward

With this approval, Woehrle said, patients diagnosed with a disease that comes with a heterogeneous and complicated group of conditions now have an option that they have deserved for a long time, highlighting the need for more research in the MPN space.

“The person living with an MPN today has a wealth of information that someone diagnosed 10 or 20 years ago did not have,” she added. “They can have an informed conversation with their physician, they will have at least the opportunity to consider clinical trials with different mechanisms of action and they will have a strong and supportive community to turn to when they need to ask a question, get a second opinion or just vent about their situation. In short, they should have hope.”

Read CURE’s original coverage from the FDA approval of Inrebic last week.