Safety Information

The use of Thyrogen^® (thyrotropin alfa for injection) should be directed by physicians knowledgeable in the management of patients with thyroid cancer.

The safety profile of patients who received Thyrogen as an adjunctive treatment for radioiodine ablation of thyroid tissue remnants who have undergone a thyroidectomy for well-differentiated thyroid cancer did not differ from that of patients who received Thyrogen for diagnostic purposes.

Thyrogen is known to cause a transient but significant rise in serum thyroid hormone concentration when given to patients who have substantial thyroid tissue still in situ. Therefore, caution should be exercised in patients with a known history of heart disease and with significant residual thyroid tissue.

Thyroglobulin (Tg) antibodies may confound the Tg assay and render Tg levels uninterpretable. Therefore, in such cases, even with a negative or low-stage Thyrogen radioiodine scan, consideration should be given to evaluating patients further with, for example, a confirmatory thyroid hormone withdrawal scan to determine the location and extent of thyroid cancer.

Thyrogen should be administered intramuscularly only. It should not be administered intravenously.

The most common adverse events (>5%) reported in clinical trials were nausea (11.9%) and headache (7.3%). Post-marketing experience indicates that Thyrogen administration may cause transient (<48 hours) influenza-like symptoms [also called flu-like symptoms (FLS)], which may include fever (>100°F/38°C), chills/shivering, myalgia/arthralgia, fatigue/asthenia/malaise, headache (non-focal), and chills.

Very rare manifestations of hypersensitivity to Thyrogen have been reported in clinical trials, post-marketing settings and in a special treatment program involving patients with advanced disease; these are urticaria, rash, pruritus, flushing and respiratory signs and symptoms. In clinical trials no patients have developed antibodies to thyrotropin alfa, either after single or repeated (27 patients) use of the product.

Information from post-marketing surveillance, as well as from the literature, suggests that elimination of Thyrogen is significantly slower in dialysis-dependent end stage renal disease (ESRD) patients, resulting in prolonged elevation of TSH levels. ESRD patients who receive Thyrogen may have markedly elevated TSH levels for several days after treatment, which may lead to increased risk of headache and nausea.

Post-marketing data include cases of atrial arrhythmias in elderly patients with pre-existing cardiac disease who received Thyrogen, and suggest that use of Thyrogen in this group should be considered carefully.

Adverse events should be reported promptly to Genzyme Medical Information at 1-800-745-4447. For more information on Thyrogen, please see Full Prescribing Information (PDF), or contact Genzyme Medical Information at 1-800-745-4447.

Considerations in the Use of Thyrogen

Even when Thyrogen-stimulated Tg testing is performed in combination with radioiodine imaging, there remains a meaningful risk of missing a diagnosis of thyroid cancer or of underestimating the extent of disease.

Although Thyrogen appeared non-inferior to thyroid hormone withholding in a study of postsurgical thyroid remnant ablation, long-term clinical outcome data are limited. 

The primary study of Thyrogen for remnant ablation employed 100mCi +/- 10% in all patients. Data are inadequate to determine if a lower dose of radioiodine would be effective when Thyrogen is used as an adjunct to radioiodine in postsurgical thyroid remnant ablation. 

A newly detectable Tg level or a Tg level rising over time after Thyrogen, or a high index of suspicion of metastatic disease, even in the setting of a negative or low-stage Thyrogen radioiodine scan, should prompt further evaluation such as thyroid hormone withdrawal to definitively establish the location and extent of thyroid cancer. 

The decisions whether to perform a Thyrogen radioiodine scan in conjunction with a Thyrogen serum Tg test and whether and when to withdraw a patient from thyroid hormone are complex. In the clinical trials, combination of Tg and scan testing did enhance the diagnostic accuracy of Thyrogen in some cases. 

The signs and symptoms of hypothyroidism which accompany thyroid hormone withdrawal are avoided with Thyrogen.

Adverse events should be reported promptly to Genzyme Medical Information at 1-800-745-4447. For more information on Thyrogen, please see Full Prescribing Information (PDF), or contact Genzyme Medical Information at 1-800-745-4447.