UCB and Otsuka Pharmaceutical Co have decided to focus their collaboration on central nervous system disorders and end their immunology pact, notably a co-development and co-promotion agreement for the Belgian drugmaker's rheumatoid arthritis biologic Cimzia in Japan.

The firms say the move is in line with Otsuka’s "clear priorities to focus in the future on CNS and oncology in its pharmaceutical business". UCB is preparing to file Cimzia (certolizumab pegol) with the Japanese Ministry of Health, Labour and Welfare during this quarter, based on positive results from a study conducted in the country which showed that the drug was associated with significant inhibition of structural joint damage progression and improvements in physical function compared to placebo.

The companies' other partnerships will continue as before. In December, Otsuka Pharmaceutical filed UCB's Neupro (rotigotine) patch for Parkinson’s disease and restless legs syndrome in Japan and has been selling the anti-epileptic Keppra(levetiracetam) in the country since 2010.

Taro Iwamoto, Otsuka's president, said that "we remain dedicated to maximising the value of these two compounds while continuing to investigate additional indications". Mark McDade, UCB's chief operating officer, added that the Brussels-based firm is "happy to continue our successful partnership" with Otsuka in CNS, but is also "committed to building on the franchises of the immunology therapeutic area in Japan", starting with Cimzia.