Johnson & Johnson and GlaxoSmithKline PLC said Thursday they are preparing to start late-stage clinical trials of an experimental rheumatoid arthritis drug.

GlaxoSmithKline and Johnson & Johnson’s Janssen Biologics unit will start two late-stage studies of sirukumab as a treatment for moderate to severe rheumatoid arthritis.

In one trial, the drug will be tested on patients who were not helped by treatment with a class of rheumatoid arthritis drugs called anti-tumor necrosis factor, or anti-TNF, agents. The other study will involve patients not helped by a class of treatments called disease-modifying antirheumatic drugs. Anti-TNF drugs include Amgen Inc.’s Enbrel and Abbott Laboratories’ Humira. Antirheumatic drugs include methotrexate.

Rheumatoid arthritis is a major area of research for drug companies because the condition is chronic, meaning patients will likely take drugs for the disease regularly and for a long time.

Shares of GlaxoSmithKline rose 34 cents to $46.20 in morning trading, and Johnson & Johnson stock lost a penny to $67.74.