Sunitinib-related thyroid dysfunction: A single-center retrospective and prospective evaluation

3092 Background: Sunitinib is a multi-target tyrosine kinase inhibitor with anti-angiogenic and anti-proliferative activity mediated by signal blockade of VEGFR1/2, KIT, PDGFRα/β, and FLT-3. Phase II/III trials have demonstrated efficacy of the oral agent in Imatinib-resistant GIST and advanced renal cell cancer (RCC). We observed several cases of thyroid dysfunction in GIST during treatment with sunitinib suggesting that the drug may be associated with hypothyroidism. We therefore assessed the incidence and severity of thyroid dysfunction in cancer patients treated with sunitinib. Methods: Thyroid function (serum TSH, T3 and free thyroxin index) and thyroid antibodies (anti-TPO, -Tg and TSH-R-Ab) were evaluated retrospectively in a cohort of patients with GIST in a Phase III trial and in an expanded access program (1st part of the investigation) and in a prospective cohort of RCC and GIST patients treated in the framework of expanded access programs (2nd part). Sunitinib was given at a daily oral dose of...