What a “game-changing” cancer therapy really looks like

Gleevec structure - Structure of Gleevec bound to the kinase domain

Gleevec binds to the kinase domain of the mutant enzyme BCR-ABL1

A 55-year-old diagnosed with chronic myeloid leukemia in 1990 could expect to lose more than 20 years of life as a result of the cancer. By 2010, the loss in expectation of life was less than 3 years.

In other words, CML patients now have a life expectancy that’s nearly equal to that of the general population, according to a Swedish study quantifying the life-saving impact of Gleevec, the targeted therapy ushered from lab bench to clinical success by Dr. Brian Druker, director of the OHSU Knight Cancer Institute, where I work as a science writer.

Hannah Bower and colleagues considered the lifespans of 2,662 patients recorded as having CML in the Swedish Cancer Registry from 1973 to 2013. They used statistical modeling to estimate changes in life expectancy and also changes in the number of years of life lost as a result of a cancer diagnosis.

CML life expectancy

The figure shows years of life expectancy at age 55 for women and men diagnosed with CML compared with the general population from 1980 to 2010. (The data are from the report by Bower and co-authors in the Journal of Clinical Oncology.)

Even before the introduction of Gleevec, the Swedish analysis shows big improvements in life expectancy during the 1990s for people with CML. The use of allogeneic stem cell transplantation, interferon alfa, more precise diagnostics, and a more structured approach in treating and monitoring patients are plausible explanations, the researchers said.

After U.S. Food and Drug Administration approval in 2001, Gleevec quickly became the gold standard for first-line treatment of CML. It is a tyrosine kinase inhibitor that specifically targets a mutant protein, BCR-ABL1, that is a driver of malignant transformation in CML. Second- and third-generation TKIs have continued to better outcomes by providing effective therapy when the cancer develops resistance to Gleevec.

Bower and colleagues note, however, that TKIs have been associated with cardiovascular adverse effects and increased incidence of other cancers that could somewhat offset the survival gains. Thus, the life expectancy of patients with CML may never equal that of the general population.

“Even so,” the researchers said, “the life expectancy of patients with CML was within 3 years of the life expectancy of the general population for diagnoses in 2010, which can be seen as a great success of CML treatment.”

Citation:

Life Expectancy of Patients With Chronic Myeloid Leukemia Approaches the Life Expectancy of the General Population by Hannah Bower, Magnus Björkholm, Paul W. Dickman, Martin Höglund, Paul C. Lambert and Therese M.-L. Andersson, Journal of Clinical Oncology, June 20, 2016.

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