Efficacy of Conservative Management of Hyperthyroidism Arising in Patients treated with Alemtuzumab for Multiple Sclerosis

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 449-497-Thyroid Neoplasia & Case Reports
Clinical
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-465
Moebar Mahzari*, Amel Arnaout and Mark S Freedman
University of Ottawa
BACKGROUND:

Alemtuzumab is a monoclonal antibody that binds CD52 receptors on lymphocytes and monocytes causing complement-mediated lysis of these cells. Alemtuzumab has been shown to reduce both the annualized relapse rate and the rate of sustained accumulation of disability in Multiple Sclerosis when compared to Interferon therapy. However, over a third of patients treated with alemtuzumab develop novel secondary autoimmune diseases of the thyroid, in particular Graves’ disease. The mechanism of thyroid autoimmunity could be related to loss of self-tolerance in the immune reconstitution phase that occurs following profound lymphopenia. Previous reports of management of hyperthyroidism in this setting have included treatment with thyroidectomy and radioactive iodine.

OBJECTIVE:

To describe our experience with the management of multiple sclerosis patients who developed hyperthyroidism as a result of alemtuzumab treatment in the clinical trials CARE MS-I & II.

RESULTS:

Of 7 patients who received alemtuzumab in the trials, 4 patients developed thyroid dysfunction. All presented with symptoms of thyrotoxicosis and had biochemically confirmed hyperthyroidism. In all 4 cases the degree of hyperthyroidism was moderate to severe with elevation of Free T4 and Free T3 hormones at presentation to at least 2-3 x upper limit of normal with concomitant suppression of TSH. In 2 of the 4 cases, the hyperthyroidism resolved within 4-8 weeks with no antithyroid treatment, and subsequently the patients became permanently hypothyroid.  In one case, treatment with antithyroid medication was discontinued after 4 months when the patient became hypothyroid. Only in one case was there evidence of sustained hyperthyroidism requiring continuous treatment with antithyroid medication methimazole for one year with good response.

CONCLUSIONS:

In this small case series, the majority of patients developing hyperthyroidism following treatment with alemtuzumab have a temporary course of hyperthyroidism pathognomonic of autoimmune thyroiditis which resolves quickly with minimal medical treatment.  In the case of Graves’ disease induced by alemtuzumab, conservative management with methimazole rather than aggressive treatment with surgery or RAI treatment is shown to be both efficacious and feasible.

Disclosure: MSF: Clinical Researcher, Bayer, Inc., Clinical Researcher, Genzyme Corporation. Nothing to Disclose: MM, AA

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm