Life with chronic myelogenous leukemia changed a decade ago with what has been called the TKI revolution. The tyrosine kinase inhibitor (TKI) medications – Gleevec, Sprycel, Tasigna, Bosulif and Iclusig – changed not only how CML is treated, but people’s expectations of what can be achieved.
But are the benefits truly revolutionary?
A study in Sweden examined patient records over the past 40 years to see how much of an impact various treatments have had on survival (Ohn and colleagues. Leuk Lymphoma 2014; epublished August 20, 2014).
For the period 1973-1979, the median survival of someone diagnosed with CML was 1.9 years. (“Median” means that one-half of the people lived more than 1.9 years and one-half lived less.) This was the first decade after the underlying cause of CML (the defect affecting chromosomes 9 and 22) was first identified. The mainstays of treatment were busulfan (first used in the 1950s) and hydroxyurea (first used in the 1960s). These drugs reduced white blood cell counts but did not have a significant impact on survival. New CML treatments introduced in the 1970s were various chemotherapy cocktails, and surgical removal of the spleen.
The second period examined in the study was 1991-1997. The two main treatments for CML during this period were first developed in the 1980s: bone marrow transplant, and interferon-alpha. Unfortunately, these therapies were not effective for the majority of people with CML so neither had much impact on long-term survival. In the Swedish database, the median survival in the early 1990s was only 4 years.
The first TKI, Gleevec, was introduced in 2001, so the third period examined was 2002-2008. The impact of this one drug was remarkable: median survival increased to 13 years. And progress has continued since then. The second-generation TKIs, Sprycel and Tasigna, were introduced in 2006, followed by Bosulif and Iclusig in 2012. So now people with CML have many options to combat their disease. And as doctors gain more experience with these medications, fine-tune their goals of treatment and improve how they monitor a person’s response to treatment (i.e. with PCR testing), we’re seeing additional gains in long-term survival. The net result: mortality due to CML has been estimated to be 70% lower now than in 1994. And over 90% of people diagnosed with CML today are expected to be alive in the year 2020.
There have been many milestones in the CML story over the past 60 years. Some of these key events have been documented in the CML-IQ infographic – our way of celebrating World CML Day and the progress that has been made. Click here for a free download.