High dose cyclophosphamide for severe refractory myasthenia gravis

Myasthenia gravis (MG) exemplifies autoimmune disease. Most patients require immunomodulating treatment, including steroids, chemotherapy, or intravenous immunoglobulin (Ig), in addition to anticholinesterase treatment. Drachman et al 1 published the beneficial effects of high dose cyclophosphamide in three patients with severe refractory myasthenia. We recount our experience of three myasthenic patients treated in a similar way. All patients participated in studies approved by the Drexel University College of Medicine and signed informed consent. These three patients with severe (class IVb) refractory MG includes all patients treated. Patients received cyclophosphamide 50 mg/kg (adjusted ideal body weight)/day over four consecutive days. Patients received antibacterial, antiviral, and antifungal prophylaxis. Haemorrhagic cystitis prophylaxis included Mesna and forced diuresis. Packed red cells and platelets were transfused to maintain haemoglobin ⩾8.5 g/dL and platelets ⩾10 × 109/L, respectively. Patients received filgrastion (G-CSF) (5 μg/kg/day) starting day 10 until their absolute neutrophil count (ANC) reached 10 × 109/L for two consecutive days. Patient 1 was diagnosed with seronegative MG at 30 years of age by a positive tensilon test and a decremental response on repetitive stimulation. Initial treatment included pyridostigine and plasmapheresis, but worsening symptoms prompted thymectomies at 12 and 18 months later. Her thymic pathology revealed thymic hyperplasia. Additional treatment with …