About Osteosarcoma


Osteosarcoma is the most common histological form of primary bone cancer and is most prevalent in children and young adults. Like the osteoblasts in normal bone, the cells that form this cancer make bone matrix. But the bone matrix of an osteosarcoma is not as strong as that of normal bones.

Osteosarcoma usually develops in areas where the bone is growing quickly, such as near the ends of the long bones. Most tumors develop in the bones around the knee, either in the lower part of the thigh bone or the upper part of the shinbone. The part of the upper arm bone close to the shoulder is the next most common site. However, osteosarcoma can develop in any bone, including the bones of the pelvis (hips), shoulder, and jaw. This is especially true in older adults.


High-dose methotrexate (HDMTX) is a common therapeutic regimen in the treatment of osteosarcoma. Methotrexate exerts its chemotherapeutic effect by being able to counteract and compete with folate in cancer cells resulting in a folate deficiency in the cells and causing their death. In order to “rescue” the cells from toxicity, folate-based therapy is used to prevent toxicity related to these extremely high methotrexate levels. Today, leucovorin is the golden standard for this type of treatment.

As the active metabolite of all clinically used folate-based therapies, arfolitixorin does not require metabolic activation and is thus tested as a replacement for leucovorin. arfolitixorin could potentially provide patients with a rescue treatment for HDMTX, not reliant upon metabolic activation that in the long-term may improve the outcome of patients with osteosarcoma.