The US FDA approved Merck & Co’s Zinplava as an add-on treatment for Clostridium difficile infections after a three-month delay.
The positive verdict comes after the FDA asked for additional information to enable their review of Zinplava (bezlotoxumab; MK 6072), delaying its approval by three months. In June, an FDA advisory committee voted by 10 to 5 with one abstention that Zinplava (bezlotoxumab) is effective for preventing the recurrence of C. difficile infections.
Merck (known as MSD outside North America) said it intends to launch Zinplava in early 2017, and Credit Suisse has suggested the drug could approach $300m in sales by 2020. A marketing authorisation application for bezlotoxumab has been filed with the EMA and is also under review.
Bezlotoxumab has been approved to reduce recurrence of C. difficile in adults who are already receiving antibacterial drug treatment for the infection and are at high risk for CDI recurrence. Merck stresses that Zinplava should not be used alone as it is not an antibacterial drug. The antibody antitoxin neutralises toxin B produced by C. difficile.
C. difficile infections are often linked to antimicrobials taken for other infections, and while unpleasant are generally not life-threatening and can usually be treated effectively with another course of antibiotics. In some cases, damage to the bowel or severe dehydration can result, and the infection can be more serious in patents with compromised immune systems.
Bezlotoxumab was originally developed by Medarex, which was acquired by Bristol-Myers Squibb in 2009. Merck licensed rights to the antibody earlier that year for $60m upfront and $165m in milestone payments.
According to market research firm GlobalData, the therapeutics and prophylactics market for C. difficile infections in the US, France, Germany, Italy, Spain, the UK and Japan will grow more than fourfold from $356m in 2014 to more than $1.5bn by 2024.
GlobalData says Merck will lead the market thanks to Dificid/Dificlir (fidaxomicin), which it predicts will be the biggest-selling antibiotic for these infections, while Zinplava could see competition in the adjunctive therapy category from the likes of Seres Therapeutics’ SER-109 and Rebiotix’ RBX2660.
Prophylactic vaccines, such as Pfizer’s PF-06425090 and Sanofi Pasteur’s ACAM-CDIFF (in phase III), are also expected to contribute to the increase in the market over the forecast period.