Cellcept responsiveness for patients with antibody-negative myasthenia gravis; is it worth a trial?

My neurologist is suggesting Cellcept, even though I have antibody-negative myasthenia gravis (hereditary...my mother, grandmother, and a couple of great-aunts all have it). He says that there are hundreds of types of antibodies, and we only now how to test for a few, so it's worth a trial of Cellcept to see if my symptoms improve. Does anyone else with antibody negative myasthenia gravis out there have any success with Cellcept? I already take Mestinon.