Advances in Treating Tenosynovial Giant Cell Tumor
Tenosynovial giant cell tumor (TGCT) is a rare type of tumor that develops in your joints, often near the end of a bone. As TGCTs grow, they can cause pain and affect your movement. Surgery has been, and still is, the primary form of treatment for TGCTs that lead to problematic symptoms. But within the last few years, an oral medication was approved for treating certain cases of TGCT, and even more may be coming down the line in the future.
Tenosynovial giant cell tumors can develop in three areas: the synovium, bursae, and tendon sheath. Your synovium is the tissue that lines your joints. Your bursae are small fluid-filled sacs that provide cushion and decrease friction between bones, tendons, and muscles in your joints. Your tendon sheath is the tissue that surrounds your tendons. TGCTs cause these areas to thicken and swell.
TGCTs can be “localized,” affecting specific areas in smaller joints in your hands and feet. They may appear as swollen nodules. TGCTs can also be “diffuse,” affecting the entirety of larger joints. Knees are the most common location, but they can also develop in your hip, ankle, elbow, or shoulder. TGCTs generally occur in people aged 25 to 50 years old.
If you have TGCT, you may experience joint pain, swelling, and difficulty moving the affected joint. In addition to a physical examination, your doctor will likely rely on radiology, usually an MRI, to make a diagnosis of tenosynovial giant cell tumor. Occasionally, a sample of fluid will be drawn from the joint or a small amount of tissue will be removed through a biopsy to confirm you have a TCGT.
Though the name may sound intimidating, tenosynovial giant cell tumors are almost always benign, or noncancerous. However, they can be aggressive and potentially damage nearby tissue and bone. An accurate diagnosis and proper treatment can help avoid permanent damage or disability from occurring.
Surgery to remove the tumor remains the primary method of treatment for tenosynovial giant cell tumors. In some cases, this is performed as a traditional “open” surgery, requiring a larger incision to access the joint. For others, arthroscopic surgery, using special equipment and a tiny camera, may be an option to remove the tumor through smaller incisions. If the tumor can’t be completely removed, radiation therapy may also be used after surgery to help shrink it.
But what if surgery isn’t a feasible option? In 2019, a drug called pexidartinib (Turalio) was approved for adults with TGCT who are unable to undergo surgery or are unlikely to benefit from surgery. This is particularly helpful for individuals with the diffuse type of TGCT since these tumors tend to grow back even after surgery, sometimes leading to multiple operations.
Pexidartinib is a type of drug called a CSF1R inhibitor. It works by blocking a protein in your cells that helps the tumor grow. Clinical trials demonstrated that pexidartinib helped reduce the size of TGCTs and improved range of motion in the affected joint. It comes in pill form and is taken twice a day.
Other medications are currently being studied as tenosynovial giant cell tumor treatment. One is a monoclonal antibody–a man-made version of an antibody like the ones produced by your immune system. It’s called cabiralizumab, and it’s given as an infusion to your vein. Another CSF1R inhibitor known as DCC-3014 is also undergoing clinical trials to determine its safety and effectiveness in treating TGCT.
If you’ve been diagnosed with TGCT, talk to your doctor about your treatment options. With one approved oral drug and other potential therapies coming down the pipeline, you can work together to find the one that’s right for you.