A new study has looked at the proportion of people with CML who achieve the key treatment milestones, which represent the optimal response to a medication at different time points (Jain and colleagues. Br J Haematol 2016;173:114-126). These milestones are developed by research groups such as European LeukemiaNet (ELN) based on clinical trials and observational studies.
For example, an optimal response to treatment is defined as a 1-log reduction or better within the first three months of treatment, according to the current ELN guidelines (Baccarani and colleagues. Blood 2013;122:872-884). After six months, the goal is to have a 2-log response or better. After one year, an optimal treatment response is better than a 3-log response.
How many people achieve these goals?
According to an analysis of 487 people with chronic-phase CML, 89% of people overall achieved the 3-month goal of a 1-log response. When analysed according to the medication that people took, 75% of those on Gleevec reached the three-month goal, compared to 89% taking Sprycel and 97% taking Tasigna.
At the six-month mark, optimal responses were seen in 41% of people on Gleevec, 86% on Sprycel and 89% on Tasigna. At one year, the proportions were 47% with Gleevec, 76% with Sprycel and 87% with Tasigna.
Reaching these treatment milestones was important because people with an optimal response were less likely to suffer a relapse, less likely to develop progressive disease, and had better overall survival. The researchers concluded that the current guidelines for treatment response reliably predict how well people will do over the longer term.