By Dr Giselle Roberts
Bone cancer. It’s not something you think about when you are a teenager. But for most osteosarcoma patients, the inevitable teenage growth spurt coincides with tumours developing in the bones around the knee, or in the upper arm bone close to the shoulder.
Up to thirty Australians under the age of 19 are diagnosed with osteosarcoma each year. What’s more, it is incredibly difficult to treat: over one third of patients fail to respond to current therapies.
Dr Christine Hawkins, an expert on cancer biology at the La Trobe Institute for Molecular Science, is investigating new treatment options for the disease.
“Osteosarcoma patients often present with a lump in the bone that might be initially disregarded as a sports injury or growing pain,” she explains. “By the time a diagnosis is made, the cancer may have spread. Thanks to advances in surgical techniques, amputation of an arm or a leg is often avoidable, but intensive chemotherapy is usually necessary. With that comes long-term side effects, which can be as severe as heart disease or therapy-related cancers.”
In research funded by The Kids’ Cancer Project and Cancer Council Victoria, Dr Hawkins and colleagues are identifying alternatives to chemo. They have discovered that a new class of anti-cancer drugs, known as Smac mimetics, can limit the growth and spread of osteosarcomas in vivo.
“The drugs affect the way that cancer cells respond to a protein called TNFα, which is produced by particular immune cells that can infiltrate tumours,” Hawkins said. “Under normal conditions, TNFα enables cancer cells to divide and spread. But when Smac mimetics are introduced, the same encounter with TNFα causes the cancer cells to die.”
“Smac mimetics converts TNFα from acting as a pro-cancerous force for evil, into an anti-cancer force for good.”
“Using chemotherapy to treat osteosarcoma improved the five-year survival rate from 20% in the 1960s to 60% by the 1980s,” Dr Hawkins said. “Unfortunately there has been no significant improvement since. Our findings provide hope that Smac mimetics may enable more osteosarcoma patients to survive their cancers.”