New hope for patients with chronic myeloid leukemia
Lisa Machado, who was diagnosed with chronic myeloid leukemia (CML) two years ago, a life-threatening form of leukemia, is grateful that another option is available to keep her cancer in check.
Tasigna (nilotinib) capsules have been approved with conditions in Canada as a new therapy for patients with CML, in the chronic phase (first phase) of the disease. Patients must be resistant to or intolerant of at least one prior therapy, including (Pr)Gleevec (imatinib mesylate), an established standard of care.
Before Gleevec, patients' options were limited. However, in a landmark clinical trial, 86.4 per cent of newly diagnosed chronic-phase Philadelphia chromosome-positive (Ph+) CML adult patients, treated with Gleevec, were alive after 7 years. Despite this success, about 20 per cent of those diagnosed with CML will be resistant or intolerant to Gleevec, driving the need for new treatment options like Tasigna.
"Thankfully, I have had an excellent response to Gleevec," says Machado. "Knowing that there are alternatives like Tasigna should Gleevec stop working for me, gives me and thousands of other Canadians with CML the ability to look to the future with a little more certainty."
What is CML?
CML is one of the four types of leukemia. It is caused by an abnormal chromosome, called the Philadelphia (Ph) chromosome which produces an abnormal cancer protein called Bcr-Abl, which is responsible for blocking the normal signal that tells the body to stop producing white blood cells. As a result, CML patients have a significantly elevated cancerous white blood cell count.
Without treatment, CML typically progresses over three to five years from the initial (chronic) phase through a transition period (accelerated phase) to a rapidly fatal form (blast crisis).
"Targeted therapy offers hope to those living with CML and will make a huge difference for many of them and their families," says Cheryl-Anne Simoneau, president and CEO of The CML Society of Canada. "While we applaud Health Canada's approval of Tasigna, we urge provincial governments to act quickly and provide reimbursement to patients who need access to this important treatment option. Available options can mean the difference between success with achieving treatment goals or having the disease become critical and or fatal for some patients."
How it works
Taken twice daily on an empty stomach, Tasigna works by inhibiting the proliferation of cells containing the Ph+ chromosome. It does this by targeting the production of the Bcr-Abl protein, which is produced only by cells containing the abnormal Ph chromosome. This protein is recognized as the key cause and driver of the overproduction of cancer-causing white blood cells in patients with Ph+ CML.
The Health Canada conditional approval was based on the interim analysis of an ongoing Phase II open label, multicenter clinical trial of 280 patients, which evaluated the drug's safety and rates of major cytogenetic response (MCyR) (where a significant reduction or no CML cells containing the Ph chromosome can be seen in a sample of bone marrow) and rates of complete hematologic response (CHR) (normalization of white blood cell counts) in Gleevec resistant or intolerant patients with Ph+ CML in chronic phase. Tasigna reduced or eliminated cells carrying the abnormal Ph chromosome in 52 per cent of patients in the chronic phase of the disease after a median treatment duration of 261 days.
"Although Gleevec remains a wonderful drug for the majority of patients who are taking it and doing well, for those patients whose disease did not respond or no longer responds, Tasigna represents an important advance," says Dr. Jeffrey Lipton, a medical oncologist with Princess Margaret Hospital in Toronto, Ontario. "Treatment options are important for cancer patients, since not all therapies work or are tolerated by every patient. This approval means Canadian physicians have another option or choice to treat their CML patients. However, a treatment is only effective when it can be accessed, so public funding is critical to allow these patients to effectively manage their cancer."
Access to treatment is paramount
It was a strange bruise on her forearm that prompted Lisa Machado, a mother of two young children, to seek medical attention. "When I found out I had CML, all I could think about was whether or not I would see my babies grow up," says Machado. "Gleevec has given me hope. It has meant that I can still be an active and involved mom even though I have cancer. The fact that there are other medications, like Tasigna, is a gift. But accessibility is key - nobody with a life-threatening disease wants to be told they can't get the medication that could save their life."
"Novartis is pleased to bring another targeted therapy to market that will benefit CML patients in Canada. We will work with governments and payers to ensure that patients have access to this innovative treatment," says Tom Rossi, president of Novartis Pharmaceuticals Canada Inc.