Current clinical trials for advanced osteosarcoma and soft tissue sarcoma

Sarcomas form a rare group of tumors greatly differing between each other in biology, behavior, and sensitivity to treatments. Their rarity and heterogeneity render it very challenging to conduct clinical trials, a phenomenon taking place in virtually all tumor types wherein detailed characterization reveals that most histopathologically categorized tumor groups consist of many small subentities. As sarcoma clinician-scientists have already long faced the challenges accompanying trials in rare tumors, lessons learned from sarcoma studies apply also to other tumor types. This review addresses current clinical trials in osteosarcomas and soft tissue sarcomas (STSs).

A wide range of antitumor agents is being explored in osteosarcomas and STS. Although studies increasingly take into account the heterogeneity of sarcomas by stratifying studies for subtypes or by performing studies in specific subtypes only, still many studies are conducted in patients unselected for sarcoma subtype thereby being at risk to miss potential antitumor activity limited to specific subgroups.

Consensus on what preclinical work is needed before starting sarcoma trials in humans, how to select patients, trial design, and the choice of endpoints is warranted. To address the challenges accompanying studies in sarcoma, global collaboration should become more intensified.