1. SAD Stage

* RA diagnosed according to the ACR

* For patients taking anti-rheumatic therapies, receipt of a stable regimen prior to randomization

* Previous treatment with biologic agents, including anti-TNF agents, permitted but discontinued for an appropriate washout period

2. MAD Stage (same as above with the addition of the following)

* Failure of at least one biologic agent, defined as lack of or loss of response or intolerance

* Active disease defined by swollen and tender count

A Study of the Safety, Pharmacokinetics, and Pharmacodynamics of MTRX1011A in Patients With Rheumatoid Arthritis