Thursday, October 28, 2004

Improving Survival and Costs for Leukemia Patients
By Julie McKeel

The life expectancy and cost-effectiveness of treatment options for patients with chronic myeloid leukemia (CML) were explored in companion articles published recently in Cancer.

Dr. Kevin Schulman, Director of the Center for Clinical and Genetic Economics, with Kevin J. Anstrom, PhD, Shelby D. Reed, PhD, Andrew S. Allen, PhD, and Jennifer A. Ludmer, MS, all of the Outcomes Research and Assessment Group, studied the long-term survival of patients newly diagnosed with chronic-phase CML given imatinib versus interferon-a plus low-dose cytarabine. The companion article compared the costs associated with both therapies.

Interferon-a was the treatment of choice for CML patients during the 1990s. However, imatinib has shown promising results across all phases of CML. In the first article, the research team estimated long-term survival rates for patients who received imatinib as the initial treatment.

The researchers estimated the long-term survival based on the rate of complete cytogenetic response (the absence of mutated cells) seen among treated patients. Two-year survival and gene-response data were gathered from 553 patients in the International Randomized Interferon versus ST571 Study (IRIS). Data from two other trials ? one studying long-term survival for patients with a positive gene response to the combination therapy (317 patients), and one studying patients with no gene response to the combination therapy (275 patients) ? also were included in the analysis.

Based on existing survival data for patients with a positive gene response and those without, the authors assumed that similar survival data applied when establishing their estimates for the same patient population.

Estimated survival for patients treated with imatinib was 6.23 years longer than that of patients treated with the combination therapy (15.3 versus 9.07 years). The advantage decreased slightly to 5.9 years longer after adjusting for quality of life.

“We found that patients achieving [a positive gene response] have superior survival compared with typical CML patients. Using two independent survival data sources, we obtained multiple estimates of life-years gained with highly consistent results,” the investigators noted.

Based on results of individual studies similar to these, imatinib has become standard therapy for patients who are newly diagnosed with chronic-phase CML. However, the current healthcare environment also demands cost-effectiveness, even for breakthrough therapies. The second article therefore estimated the long-term cost-effectiveness of imatinib versus combination therapy in the treatment of these patients.

Cost, survival, and quality-adjusted survival estimates were based on data from the first article. Survival estimates also were based on published data for patients with and without mutated cells who were treated with combination therapy.

Compared with combination therapy, imatinib is a cost-effective initial treatment option. Estimated total lifetime costs for patients first treated with imatinib were $242,000 higher than those first given combination treatment. As noted above, the estimated survival for these patients averages 6.2 years longer.

After adjustment for both quality of life and future cost increases, the imatinib group survival estimate was almost 4 years longer, and their costs were $168,000 higher. This translates to an extra $43,300 in costs per additional year of life saved with imatinib treatment.

The traditional threshold for cost-effectiveness is having extra costs of less than $50,000 per additional year of life with a given treatment, adjusted for quality of life. Thus the results for imatinib fall well within this range.

“As additional [treatment] strategies emerge and long-term data become available, it will be important to evaluate the cost-effectiveness of add-on therapies, update our evaluation of existing therapies, and determine how well our analysis reflects real-world experience, “ note the investigators. “Our analysis shows that imatinib is a cost-effective initial treatment option for newly diagnosed chronic-phase CML patients.”

Novartis, the maker of imatinib, funded these analyses.