Molecularly targeted agents have shown activity in
soft tissue sarcoma (STS) and benign connective tissue
tumors over the past ten years, but response rates differ by histologic subtype. The field of molecularly targeted agents in
sarcoma is increasingly complex. Often, clinicians must rely on phase II data or even case series due to the rarity of these diseases. In subtypes with a clear role of specific factors in the pathophysiology of disease, such as
giant cell tumor of the bone and diffuse-type
tenosynovial giant cell tumor, it is reasonable to treat with newer targeted
therapies, when available, in place of
chemotherapy when systemic treatment is needed to control disease. In diseases without documented implication of a pathway in disease pathogenesis (e.g.
soft tissue sarcoma and
vascular endothelial growth factor), clear benefit from
drug treatment should be established in randomized phase III trials before implementation into routine clinical practice. Histologic subtype will continue to emerge as a critical factor in treatment selection as we learn more about the molecular drivers of
tumor growth and survival in different subtypes. Many of the drugs that have been recently developed affect
tumor growth more than survival, therefore progression-free survival may be a more clinically relevant intermediate endpoint than objective response rate using Response Evaluation Criteria In Solid Tumors (RECIST) in early phase
sarcoma trials. Because of the rarity of disease and increasing need for multidisciplinary management, patients with connective tissue
tumors should be evaluated at a center with expertise in these diseases. Participation in clinical trials, when available, is highly encouraged.