Now widely available across Canada as a third-line treatment for B-cell lymphomas, CAR T focus now on second-line treatment.
Researchers in cancer medicine have been studying immunotherapies for decades. One form of immunotherapy is stem cell transplants, which have been the standard of care in many types of blood cancers, such as high-risk leukemias, myeloma, and lymphoma, especially where patients haven’t responded to chemotherapy treatment.
Chimeric antigen receptor therapy (CAR T) is a newer form of immunotherapy that has shown increased survival and cure rates when used as a treatment in patients with relapsed or unresponsive B-cell lymphomas. “We’ve seen long-term survival in about 40 per cent of those patients, which is far superior to the long-held gold standard of chemotherapy followed by stem cell transplant,” says Dr. John Kuruvilla, a hematologist in the Division of Medical Oncology and Hematology at Princess Margaret Hospital.
Using patients’ own T-cells to fight cancer
CAR T therapy involves collecting T cells (blood lymphocytes) from the patient, sending them to a lab where they’re genetically modified to target specific cancer markers, and then infusing them back into the patient’s body. Prior to the infusion, patients are prepared with a treatment called lymphodepletion with a standard dose of chemotherapy to ensure the right environment for those cells to expand, multiply, and target the cancer cells.
Getting to where we are today with CAR T therapy has taken decades of work in the lab, well-designed studies, and clinical trials with hundreds of patients.
“Getting to where we are today with CAR T therapy has taken decades of work in the lab, well-designed studies, and clinical trials with hundreds of patients,” says Dr. Kuruvilla. One major challenge was overcoming the tendency of the rapidly growing T cells to cause a cytokine storm in the patient — an intense immune activation resulting in systemic inflammation that could cause extreme illness or even death. “Over time, we learned how to manage that safely without compromising the potential effectiveness of the treatment,” says Dr. Kuruvilla.
Among the first genetically engineered cell therapies
As a third-line cancer treatment for certain types of lymphoma, CAR T has been more widely approved and funded for patients over the last few years in Canada. Initially available only in Ontario, Quebec, and Alberta, there’s now a CAR T treatment centre in nearly every province. Recent clinical trial data shows that CAR T also offers significant promise as a second-line therapy, however, this is not currently available to patients in Canada. “We’re hoping it will soon be funded as a second-line treatment, particularly in patients with the highest risk aggressive B-cell lymphomas who don’t receive remission with their first treatment or whose cancer starts to grow within a year of completion of treatment,” says Dr. Kuruvilla.
Having more CAR T treatment centres across Canada is a step in the right direction, according to Sabrina Hanna, Chief Innovation Officer at the cancer collaborative. “It’s a huge improvement in that a very sick patient from B.C. eventually won’t have to travel to Ontario for treatment, but we’re still not in a place where it’s equitable for all patients, as many still have to travel from their communities to the larger centres.” Hanna would like to see CAR T funded as an earlier treatment line when patients are less sick, have fewer comorbidities, and have a chance at a better outcome. “Quality of life is important and, while with CAR T the patient still has to go through the lymphodepletion process, the side effects are less severe, so patient preferences and needs should be taken into account when making these types of policy decisions,” she says.
Learn more about whether CAR-T therapy is a suitable option for you.