Thymic carcinoma is an exceptionally rare
tumor, which has a very poor prognosis, differing from
thymoma. Although cytotoxic
chemotherapy is commonly used to treat advanced
thymic carcinoma, its effectiveness has not been found to be sufficient. There are several reports that
thymic carcinoma also harbors an oncogenic driver mutation, similar to
lung cancer. A patient with a c-kit mutation-positive
thymic carcinoma received
imatinib followed by
sunitinib consecutively, which are both c-Kit inhibitors. Although the patient had achieved long-term disease control for 21 months, the primary lesion and pulmonary
metastases had increased in size by November, 2014. Following failure of
imatinib treatment, the patient received
sunitinib, a multiple
kinase inhibitor, initiated in December, 2014. Following administration of
sunitinib, a computed tomography scan revealed a partial response and the disease was effectively controlled with continued
sunitinib treatment for 6 months, up to June, 2015. The patient achieved long-term disease control (~27 months) with
imatinib followed by
sunitinib. The efficacy of consecutive
molecular-targeted therapy for
thymic carcinoma was demonstrated in this case. Therefore,
thymic carcinoma with oncogenic driver mutations should be treated with molecular-targeted agents rather than with cytotoxic drugs, and it may be suitable to treat c-kit mutation-positive
thymic carcinoma as a mediastinal
gastrointestinal stromal tumor.