Recombinant Human Thyrotropin Noninferior to Thyroid Hormone Withdrawal With Radioiodine Therapy: Presented at ATA

By Frances Morin

Washington, DC -- October 10, 2018 -- The use of recombinant human thyrotropin (rhTSH) is no less effective than thyroid hormone withdrawal in preparation of thyroidectomy and radioiodine (RAI) therapy for differentiated thyroid cancer (DTC), regardless of other outcome predictors, according to a study presented here at the 88th Annual Meeting of the American Thyroid Association (ATA).

“Our study shows noninferiority of rhTSH compared with thyroid hormone withdrawal for adjuvant RAI therapy in a large cohort of N1 DTC patients at low to intermediate recurrence risk,” said David Taieb, MD, PhD, Nuclear Medicine Department, La Timone Hospital, Marseille, France, on October 5.

The use of rhTSH is approved for and seen as a useful alternative to thyroid hormone withdrawal in the preparation of RAI of N1 DTC patients, which can cause hypothyroidism in most patients, whereas rhTSH has no known long-term side effects.

However, data on its effectiveness and the role of factors such as the extent of lymph node involvement are limited.

Dr. Taieb noted that this is important because “the presence of nodal involvement can be associated with decreased disease-free survival.”

To more extensively investigate the effects of rhTSH versus thyroid hormone withdrawal in the multicentre study, Dr. Taieb and colleagues evaluated 404 pT1 to pT3 DTC patients with lymph node metastases, including 205 who were prepared with rhTSH and 199 with thyroid hormone withdrawal.

The patients were matched in the 2 groups according to age (5), with ~90% in each group having ≤5.

The results in the intent-to-treat population showed that at the first follow-up, performed at 6 to 18 months after RAI therapy, the rate of disease-free control in the rhTSH group (75.1%; 95% confidence interval [CI], 68.6-80.9) was noninferior to the hormone-withdrawal group (71.9%; 95% CI, 65.1-78.0).

At the last follow-up, between 29.7 and 36.7 months, complete remission was achieved in 83.5% of the rhTSH group and 81.5% of the hormone-withdrawal group, again showing noninferiority.

None of the prognostic factors that were evaluated, including gender, sex, number, location of regional lymph node involvement (N1a, N1b), and tumour stage, were found to be associated with different RAI outcomes after rhTSH or thyroid hormone-withdrawal therapy.

Rates of abnormal RAI uptake foci on posttherapy scintigraphy were similar in the groups (15.6% in the rhTSH group vs 14.6% in the hormone-withdrawal group).

“The success rate we found in the study is not influenced by prognostic factors, including administrated RAI activities and DFS is not different between rhTSH and thyroid hormone withdrawal,” concluded Dr. Taieb.

Additional long-term follow-up data are expected soon.

Funding for the study was provided by Sanofi Genzyme.

[Recombinant Human Thyrotropin vs. Thyroid Hormone Withdrawal in Radioactive Iodine Therapy of Thyroid Cancer Patients With Nodal Metastatic Disease: Influence of Prognostic Factors on Follow-Up Clinical Status. Abstract 21]

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