October 18th, 2013
FDA Approves New Pulmonary Hypertension Drug from Actelion
Larry Husten, PHD
The FDA today approved macitentan (Opsumit, Actelion), a new oral endothelin-receptor antagonist that is an enhanced version of the company’s bosentan (Tracleer). The drug is indicated to delay disease progression in patients who have pulmonary arterial hypertension (WHO Group I).
Last August the results of the pivotal phase 3 trial, SERAPHIN (Study with an Endothelin Receptor Antagonist in Pulmonary Arterial Hypertension to Improve Clinical Outcome), were published in the New England Journal of Medicine. After 2 years of treatment with macitentan or placebo, significant reductions in the primary endpoint (a composite endpoint of death, atrial septostomy, lung transplantation, initiation of treatment with intravenous or subcutaneous prostanoids, or worsening of pulmonary arterial hypertension) occurred in the patients who took macitentan. The best results were seen in the group which took 10 mg of macitentan, the dose approved by the FDA.
The Opsumit label will contain a boxed warning that the drug should not be used in pregnant women since it can harm the fetus. Women will be only able to receive the drug through a Risk Evaluation and Mitigation Strategy (REMS) Program. The program will require prescribers and pharmacies to be certified. Female patients will need to be enrolled in the program and comply with applicable pregnancy testing and contraception requirements, the FDA said.
Actelion said the drug would be available to U.S. patients in November.
The approval of macitentan comes a little more than a week after the FDA approved Bayer HealthCare’s riociguat (Adempas). The drug, a soluble guanylate cyclase stimulator thought to have vasodilating, antiproliferative, and antifibrotic effects, received a broader indication that included not only pulmonary arterial hypertension but also persistent or recurrent chronic thromboembolic pulmonary hypertension (CTEPH) after surgical treatment or inoperable CTEPH to improve exercise capacity and WHO functional class. Riociguat also contained a boxed warning and women will likewise be able to receive the drug only through a REMS program.
Macicentan is a dual endothelial receptor antagonist for PAH, therefore similar to bosentan, but differs from ambrisentan which is selective for type A endothelin receptors. From a practical standpoint, macicentan is a once a day medicine, as is ambrisentan, whereas bosentan is a twice a day medicine. In clinical trials, less LFT abnormalities have been observed with macicentan and ambrisentan than were seen with bosentan. It is important to remember that these medicines and the benefits observed in these trials, have only been demonstrated in pulmonary arterial hypertension (PAH), also known as Group 1 PH, and are not indicated in pulmonary hypertension secondary to heart disease or lung disease- which together account for almost 80% of the PH seen in community practice.
John, I agree. Judith