Cost-Effectiveness of Adding Imatinib to Chemotherapy in Adult Patients with Chromosom-Positive Acute Lymphoblastic Leukemia (Ph+ALL): A Canadian Perspective

BACKGROUND: Ph+ALL is a rare, high-risk, aggressive form of acute leukemia, affecting primarily adults and the elderly. Patients with high-risk forms of ALL typically have extremely poor prognosis and incur high disease-related costs. Successful use of imatinib in patients with Ph+CML has led to the administration of imatinib in recent clinical studies for patients with Ph+ALL. Given the changing treatment landscape of Ph+ALL and the recent development of additional targeted treatments for this disease, an appraisal of the economic burden associated with Ph+ALL is warranted for evaluation of appropriate treatment options and the potential value associated with novel therapies. This study explores the cost effectiveness of imatinib plus conventional chemotherapy (CC) regimens versus CC alone in adult Ph+ALL patients.

METHODS: A Markov model simulated a hypothetical cohort of 1000 adult Ph+ALL patients receiving imatinib+CC or CC alone. Patients were distributed over time into three health states: alive without disease progression (DFS), alive with disease progression (DS), or dead. Probabilities of being in the states were derived from the published literature. In the absence of relevant data pertaining to Ph+ALL, assumptions about costs and utilities were derived from a cost analysis of CML. A Canadian health care payer perspective was considered, therefore only direct medical costs were included in the analysis. Patients were followed for a total of ten years in monthly intervals. All outcomes were discounted at a 5% rate per annum.

RESULTS: Based on the model framework and assumptions, the total discounted survival was 1.09 years for CC and 4.13 years for imatinib+CC. Total discounted disease free survival was 0.76 year for CC and 2.69 years for imatinib+CC. Assuming utility weights of 0.854 and 0.596 for DFS and DS, respectively, the total discounted quality adjusted life years (QALY) were estimated to be 0.84 versus 3.16 for CC and imatinib+CC, respectively. Thus, the net incremental gain in discounted quality adjusted survival was 2.32 QALYs. The monthly costs of DFS and DS were estimated at $168 and $848, respectively. The net costs associated with imatinib were $101,929. The incremental cost per QALY of imatinib+CC v. CC alone was approximately $44,048 (i.e., $101,929 divided by 2.32 QALYs).

CONCLUSIONS: Our results suggest that imatinib in the treatment of Ph+ALL is a cost-effective use of health-care resources, and should be considered in patients who are appropriate candidates for such therapy.