Targeted Drug Helps Leukemia Patients Resistant to Initial Therapy

Many patients with chronic myeloid leukemia (CML) who have not responded to interferon treatments have now been found to experience long-term benefits when switched to the targeted drug imatinib, which blocks the protein encoded by a particular cancer-causing gene.

While imatinib is now the standard drug given after a diagnosis of CML, there remain many thousands of CML patients who have undergone unsuccessful interferon treatment then switched to imatinib. However, long-term response studies have not been reported.

To investigate, Hagop Kantarjian, MD, of the University of Texas MD Anderson Cancer Center (MD Anderson; Houston, TX, USA) and colleagues analyzed 368 CML patients from MD Anderson who started taking imatinib (formally, imatinib mesylate) after failing to respond to interferon. The estimated 10-year survival rate was 68%, the progression-free survival rate was 67%, and the event-free survival rate was 51%. In multivariate analysis, age ≥60 years, hemoglobin <10 g/dL, bone marrow basophils ≥5%, any peripheral blasts, and clonal evolution were independent adverse factors for survival. The estimated 7-year survival rate according to the presence of no factors (n = 154), 1 or 2 factors (n = 190), or ≥3 factors (n = 24) were 93%, 70%, and 25%, respectively (P < .01).

In summary, the team estimated that 68 percent of patients survived for at least 10 years, a major improvement compared to previous research indicating that only 20% to 30% of patients who do not respond to interferon therapy and have no access to imatinib survive this long.

The study was published online ahead of print on February 27, 2012, in the American Cancer Society sponsored journal Cancer.

Related Links:
University of Texas MD Anderson Cancer Center