Experience with starting tacrolimus postoperatively after transsternal extended thymectomy in patients with myasthenia gravis.

BACKGROUND: Thymectomy is a standard treatment of myasthenia gravis (MG). Immunomodulating agents are frequently given during the post-thymectomy latency period until complete remission is fully consolidated, but serious side effects is a relevant clinical problem for patients on long-term immunomodulating treatment.

OBJECTIVE: To assess the effectiveness of starting tacrolimus in the immediate postoperative period in MG patients undergoing transsternal extended thymectomy, with complete stable remission (CSR) as the primary outcome of the study.

METHODS: Forty-eight MG patients received tacrolimus, 0.1 mg/kg per day b.i.d. (started 24 h after thymectomy) and prednisone 1.5 mg/kg/day. Histologically, 34 patients had hyperplasia, 20 thymic involution, and 14 thymoma. Of the 48 patients, 40 completed 1 year of tacrolimus therapy, 38 completed 2 years, 27 completed 3 years, 21 completed 4 years, and 9 more than 5 years. Mean dose of tacrolimus was 4.9 mg/day (range 2-8 mg/day) with a mean plasma drug concentration of 7.6 ng/mL (range 7-9 ng/mL). Prednisone could be withdrawn after the first year in 93.7% of patients and at 2 years in 100%.

RESULTS: The mean follow-up was 24.4 months, SD 17.3 (range 6-60 months). Improvement of muscular strength and decrease of anti-AChR antibodies were statistically significant (p < 0.001) shortly after operation. CSR was obtained in 33.4% of patients, pharmacological remission in 62.6%; 4% of patients had minimal symptoms. None of the patients with thymoma achieved CSR. The estimated median follow-up to obtain a CSR was 37.9 months (95% confidence interval [CI] 26.4-49.5 months). The overall crude CSR rate was 33.4%, with 47% for non-thymoma patients. The probability to achieve CSR at 3 years was 67% for the non-thymomatous group.

CONCLUSIONS: Long-term immune-directed treatment with tacrolimus to improve the effectiveness of thymectomy in MG is feasible and was associated with a high rate of CSR in patients without thymoma.