DUBLIN – Shares in Ablynx NV dropped 18 percent Thursday morning on news that Abbvie Inc. decided not to trigger an option to take forward vobarilizumab in rheumatoid arthritis (RA). Vobarilizumab, an interleukin-6 receptor (IL-6R) inhibitor, recently demonstrated solid efficacy in a phase IIb head-to-head monotherapy trial against Actemra (tocilizumab, Roche Holding AG) and in a phase IIb combination trial with methotrexate.