Tumor response and thyroglobulin change in differentiated thyroid carcinoma treated with dabrafenib plus trametinib.

Purpose: It has been reported that treatment response does not necessarily correlate with the change of thyroglobulin (Tg) during dabrafenib treatment in differentiated thyroid carcinoma (DTC). This study aimed to assess the association between the clinical response and Tg changes or inflammatory biomarkers in a real-world setting.

Methods: This retrospective multi center cohort study included 22 BRAF-mutated DTC patients treated with dabrafenib plus trametinib in three academic institutions.

Results: All 22 patients harbored the BRAFV600E mutation. Twenty-one patients (95%) had papillary thyroid carcinoma histology, and one had poorly differentiated thyroid carcinoma histology. Among 16 patients without Tg antibody, 14 patients (88%) experienced an increase in their Tg levels one month after the initiation of dabrafenib plus trametinib. In addition, 11 patients (69%) experienced an increase in their Tg levels at the best clinical response. Among these 11 patients who had an increase in Tg level at the best clinical response, the numbers of patients who had partial response, stable disease, and progressive disease were 3, 8, and 0, respectively. Among the 19 patients in whom neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and lymphocyte-to-monocyte ratio were measured at baseline, no distinctive trends were identified between clinical response and change in those inflammatory biomarkers.

Conclusions: Tg changes during dabrafenib plus trametinib treatment may not be associated with clinical response to dabrafenib plus trametinib treatment. Further study is needed to clarify the association between Tg level or inflammatory biomarkers change and clinical response to dabrafenib plus trametinib treatment.