drugs

Thyrogen - thyrotropin alfa

What is Thyrogen?

Thyrogen is a powder for the preparation of a solution to be administered by injection. Each vial contains 0.9 mg of the active ingredient thyrotropin alfa.

What is Thyrogen used for?

Thyrogen is used in patients undergoing thyroid removal (thyroidectomy) surgery because they have cancer. Thyrogen is used with the thyroglobulin test with or without radioactive iodine scanning assay (131I) to identify any thyroid cells not removed by surgery. Thyrogen can also be used in combination with higher doses of radioactive iodine for the ablation (elimination) of any thyroid cells not removed.

The medicine can only be obtained with a prescription.

How is Thyrogen used?

Thyrogen should be used under the supervision of a doctor experienced in thyroid cancer. The administration takes place via two injections of 0.9 mg each performed in the gluteal muscle 24 hours apart. If Thyrogen is used with a radioactive iodine scanning test, it should be administered 24 hours after the last Thyrogen injection, after which the test should be performed 48-72 hours after such administration. If Thyrogen is administered with higher doses of radioactive iodine in ablation therapy, iodine should also in this case be administered 24 hours after the last Thyrogen injection, however the scanning test, which is intended to ascertain the actual ablation of all cells not removed with surgery will be performed after a longer interval (a few days).

How does Thyrogen work?

The active ingredient in Thyrogen, thyrotropin alfa, is used to conduct thyroid function tests. It is a natural replica of TSH (thyroid stimulating hormone) produced by the method known as "recombinant DNA technology": that is, it is obtained from a cell in which a gene (DNA) has been introduced that makes it able to produce the hormone.

Patients who have had their thyroid glands removed are subjected to a replacement therapy based on thyroxine (a hormone produced by the thyroid) which involves inactivation of any thyroid cells still present in the body, stopping the production of TSH. However, TSH is necessary for post-operative examinations aimed at detecting the possible presence of non-excised thyroid cells, since active cells are easier to detect. Thyrogen behaves like TSH, stimulating all the cells left in the thyroid, including the cancerous ones. The activity of the latter can be detected by measuring the levels of a protein, thyroglobulin, or by acquiring diagnostic images with the aid of radioactive iodine, as the active thyroid cells absorb the iodine thus becoming visible on examination . At higher doses, radioactive iodine can also suppress all remaining thyroid cells.

How has Thyrogen been studied?

Thyrogen has been the subject of two studies involving a total of 406 patients who underwent thyroidectomy and who had to be examined to detect the possible presence of non-excised thyroid cells. For each individual patient, repeated measurement of thyroglobulin production and absorption of radioactive iodine was performed once after treatment with Thyrogen and once during suppressive hormone therapy (THST). THST makes it possible to restore the natural production of TSH in the body by interrupting thyroxine replacement therapy for 4-6 weeks. The results of the two measurements were then compared to see if there was a match.

Thyrogen was also the subject of a study on thyroid tissue ablation conducted on 63 patients with thyroid cancer treated with 131I after Thyrogen administration or after THST. The main efficacy parameter was based on an eight-month control from the treatment aimed at determining whether thyroid cells were still present in the patient.

What benefit has Thyrogen shown during the studies?

In detecting the thyroid cells left after surgery, the efficacy of Thyrogen in stimulating thyroglobulin production and absorption of radioactive iodine was comparable to that obtained with THST. The use of Thyrogen allows the patient to continue the replacement therapy before the execution of the examination, with a consequent improvement in the quality of life. Regarding the ablation of thyroid tissues, images with radioactive iodine obtained eight months after treatment have shown 100% success of both treatments.

What is the risk associated with Thyrogen?

The most common side effect associated with Thyrogen (ie that seen in more than 1 in 10 patients) is nausea. For the full list of all side effects reported with Thyrogen, see the Package Leaflet. Thyrogen should not be used in patients who may be hypersensitive (allergic) to bovine TSH or to any of the excipients. Thyrogen should not be used during pregnancy.

Why has Thyrogen been approved?

The Committee for Medicinal Products for Human Use (CHMP) decided that Thyrogen's benefits are greater than its risks when used in patients undergoing thyroidectomy who receive hormone suppressive therapy (THST) for the detection of thyroid residues and carcinoma of the well-differentiated thyroid (with serum thyroglobulin examination with or without radioactive iodine images) and for ablation of residual thyroid tissues in combination with radioactive iodine (131I) and has therefore recommended the release of the product marketing authorization .

More information on Thyrogen:

On 9 March 2000, the European Commission issued a marketing authorization valid for Thyrogen to Genzyme Europe BV, valid throughout the European Union. The marketing authorization was renewed on 9 March 2005.

The full EPAR for Thyrogen can be found here.

Last update of this summary: 09-2007.