Ubenimex is a compound that Eiger BioPharmaceutical is developing for the treatment of pulmonary arterial hypertension (PAH).

PAH is a high blood pressure condition that damages tiny arteries in the lungs known as pulmonary arterioles. The damage puts pressure on the lower right chamber, or right ventricle, of the heart, because it has to work harder to pump blood through the lungs.

As the pressure builds, the heart muscles weaken and eventually fail. These problems make PAH a progressive, life-threatening disease.

How Ubenimex works

Ubenimex is an oral, small-molecule inhibitor of leukotriene A4 hydrolase (LTA4H), an enzyme that plays a key role in the formation of inflammation-causing agents known as leukortriene B4 (LTB4).

High levels of LTB4 are associated with the inflammation in PAH that leads to obstructed arterioles, constricted blood vessels, and deterioration in heart function. By  blocking the formation of LTB4, Ubenimex is taking a new therapeutic approach to treating PAH.

Ubenimex and clinical trials

Eiger is evaluating Ubenimex in a 24-week Phase 2 clinical trial (NCT02664558). The multicenter, randomized, double-blind, placebo-controlled study is looking at the effectiveness, safety and tolerability of Ebenimex in PAH patients.

The study’s main objective is determining whether Ubenimex can lower patients’ vascular pulmonary resistance by limiting the blood flowing from the right ventricle of the lungs to the pulmonary artery.

Eiger announced the completion of patient enrollment in the trial in May 2017. The 61 patients are being evaluated at 45 sites in the United States and Canada.

Those who complete the 24-week treatment period will be eligible to enroll in an open-label extension study, the company said. That study will evaluate the effectiveness, safety, and tolerability of Ubenimex in patients treated more than 24 weeks.

The U.S. Food and Drug Administration and the European Medicines Agency have designed Ubenimex an orphan drug to accelerate its regulatory approval process.

Ubenimex has been approved in Japan under the brand name Bestatin. Japanese doctors are prescribing it to non-lymphocytic leukemia patients as an add-on treatment to chemotherapy to maintain patients’ remission and extend their survival.


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