What’s new in osteosarcoma research and treatment?
Research on osteosarcoma is now being done at medical centers, university hospitals, and other institutions across the world.
Researchers are learning more about what makes osteosarcoma cells different from normal bone cells. Knowing more about the changes in osteosarcoma cells might eventually result in specific treatments that exploit these changes. For example, researchers have found that osteosarcoma cells often have large amounts of a substance called GD2 on their surfaces. Drugs that target GD2 are already used to treat neuroblastoma (another cancer often seen in children), and are now being studied for use against osteosarcoma.
Tests of gene changes called gene expression profiling might help predict the behavior of each tumor, such as how they will respond to certain types of chemotherapy. These are still being tested in clinical trials.
Great advances have been made in treating osteosarcoma in the past few decades. Still, more research is needed to learn how best to manage hard-to-treat osteosarcomas, such as those that have already spread when they are found. Many clinical trials are focusing on treating osteosarcoma using a variety of strategies.
Doctors now have a much better understanding of the typical growth and spread of osteosarcomas than they did in the past. This, along with newer imaging tests that better define the extent of tumors, lets them plan surgeries to remove the cancer while sparing as much normal tissue as possible.
Some newer types of internal prostheses (man-made devices used to replace pieces of bone) can now be expanded without the need for more surgery. This is especially important for children, who in the past often needed several operations to replace the prosthesis with a larger one as they grew.
Osteosarcoma cells are not killed easily by radiation, so high doses are needed to have an effect. This has limited the use of radiation, because such high doses can often cause unacceptable side effects. Newer forms of radiation let doctors focus the radiation more precisely on the tumor. This limits the doses received by nearby healthy tissues and may allow higher doses to be used on the tumor itself.
Intensity-modulated radiation therapy (IMRT) is an example of an advanced form of therapy. In this technique, radiation beams are shaped to fit the tumor and aimed at the tumor from several angles. The intensity (strength) of the beams can also be adjusted to limit the dose reaching nearby normal tissues. This may let the doctor deliver a higher dose to the tumor. Many major hospitals and cancer centers now use IMRT, especially for tumors in hard-to-treat areas such as the spine or pelvis (hip bones).
A newer approach is to use radioactive particles instead of x-rays to deliver the radiation. One example uses protons, which are positive parts of atoms. Unlike x-rays, which release energy both before and after they hit their target, protons cause little damage to tissues they pass through and then release their energy after traveling a certain distance. Doctors can use this property to deliver more radiation to the tumor and to do less damage to nearby normal tissues. As with IMRT, proton beam therapy may be helpful for hard-to-treat tumors, such as those on the spine or pelvic bones. The machines needed to make protons are expensive, and there are only a handful of them in the United States at this time.
An even newer approach uses carbon ions, which are heavier than protons and cause more damage to cancer cells. This therapy is still in the earliest stages of development and is only available in a few centers around the world.
Doctors are also studying newer forms of radioactive drugs to treat osteosarcoma that has spread to many bones. One example is radium-223 (Xofigo), which might work better than the drugs now used.
Clinical trials are being done to determine the best combinations of chemotherapy (chemo) drugs, as well as the best time to give them. Newer chemo drugs are being studied as well.
The lungs are the most common place for osteosarcoma to spread. Inhaled forms of some chemo drugs (such as cisplatin) are being studied for patients whose cancer has spread to their lungs. Early results have been promising.
Other new forms of treatment
Chemo drugs are often effective against osteosarcoma, but sometimes they don’t work or the cancer becomes resistant to them over time. Researchers are studying newer types of drugs that attack osteosarcoma cells in different ways
Immunotherapy drugs: Clinical trials are looking into ways to help the patient’s own immune system recognize and attack the osteosarcoma cells. An experimental immune-modulating drug called muramyl tripeptide (also known as MTP or mifamurtide) has been shown to help some patients when added to chemotherapy.
Targeted therapy drugs: Doctors are also studying new medicines that target specific molecules on the cancer cells. These are known as targeted therapies. Some of these are man-made versions of immune system proteins, known as monoclonal antibodies. These antibodies attach to certain proteins on the cancer cell and help to stop the growth or kill the cancer cells. Examples now being studied include antibodies against the insulin-like growth factor receptor 1 (IGF-1R), a protein that may help cancer cells grow.
Other targeted drugs being studied for use against osteosarcoma include:
- Drugs that affect a tumor’s ability to make new blood vessels, such as sorafenib (Nexavar) and pazopanib (Votrient).
- Drugs that target the mTOR protein, such as temsirolimus (Torisel) and everolimus (Afinitor).
Drugs that affect the bones: Other drugs that target bone cells called osteoclasts may also be useful against osteosarcoma. Bisphosphonates are a group of drugs that are already used to treat osteoporosis (bone thinning) and certain cancers that have spread to the bone. Some of these drugs, such as pamidronate and zoledronic acid, are now being studied for use in osteosarcoma as well. Another drug that affects bones, known as saracatinib (AZD0530), is also being studied.
Last Medical Review: 04/18/2014
Last Revised: 04/18/2014