Pioglitazone Therapy of PAX8-PPARγ Fusion Protein Thyroid Carcinoma
Thomas J Giordano, Bryan R Haugen, Steven I Sherman, Manisha H Shah, Elaine M Caoili, Ronald J Koenig, Thomas J Giordano, Bryan R Haugen, Steven I Sherman, Manisha H Shah, Elaine M Caoili, Ronald J Koenig
Abstract
Context: A subset of thyroid carcinomas expresses an oncogenic paired box 8 (PAX8) and peroxisome proliferator activated receptor γ (PPARγ) fusion protein (PPFP). The PPARγ/PPFP ligand pioglitazone is highly therapeutic in a transgenic mouse model of PPFP thyroid carcinoma, but whether pioglitazone is therapeutic in patients with PPFP thyroid carcinoma is unknown.
Case description: Tumor blocks from 40 patients with progressive thyroid cancer despite standard-of-care therapy were screened for PPFP, and the tumor from only one patient (2.5%) was positive. The patient had a 6.0-cm acetabular soft tissue metastasis from Hürthle cell carcinoma that caused severe pain on weight bearing and had a serum thyroglobulin level of 1974 ng/mL. After 24 weeks of therapy with pioglitazone, the metastatic lesion was 3.9 cm, the thyroglobulin level was 49.4 ng/mL, and the patient was pain-free. Thirteen months after discontinuation of pioglitazone, the metastatic lesion was 3.6 cm, the thyroglobulin level was 4.7 ng/mL, and the patient remained pain-free.
Conclusions: Pioglitazone may be therapeutic in patients with PPFP thyroid cancer. However, thyroid cancers that are progressive despite standard-of-care therapy appear to only rarely express PPFP.
Trial registration: ClinicalTrials.gov NCT01655719.
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Source: PubMed