Bayer HealthCare of Germany and its U.S. drug development partner Regeneron Pharmaceuticals have agreed to collaborate on Derived Growth Factor Receptor Beta (PDGFR-β) as a potential combination therapy with their jointly developed treatment for wet age-related macular degeneration, Eylea (aflibercept).

According to Bayer, preclinical data suggests that, given the multi-factorial nature of wet AMD, combining PDGFR-β blockade with Eylea's vascular endothelial growth factor (VEGF) blockade can offer additional advantages not achievable with Eylea alone. The first human clinical studies are currently planned to begin in early 2014.

The potential next-generation product candidate will combine Regeneron's PDGFR-β antibody and Eylea in a single intravitreal injection, the companies said.

Under the agreement, Bayer HealthCare will make an upfront payment of $25.5 million to Regeneron and will share global development costs for the program. Outside the U.S., the German company will have exclusive commercialization rights to the combination product. In these markets, however, it will share profits equally with its U.S. partner. Regeneron will retain not only exclusive commercialization rights but also all profits in the U.S.

Additionally, Regeneron is eligible to receive up to $40 million in option and milestone payments from Bayer HealthCare, which also will be responsible for certain payments due to a third party, including royalties on ex-U.S. sales and a share of development milestones.

Bayer is due to react soon to challenges to the reimbursement of Eylea by German health insurance companies. The Institute for Quality and Efficiency in Health Care (IQWiG), a healthcare cost watchdog, said recently it could not assess whether the drug was more effective than a rival product because of differences in the way the drug was administrated in clinical trials.