The introduction of generic imatinib will be the most cost-effective tyrosine kinase inhibitor for the initial treatment of chronic myeloid leukemia, according to study results.
The price of imatinib (Gleevec, Novartis) is expected to decrease substantially following the loss of patent protection, whereas other branded TKI costs are expected to remain high, according to the researchers.
“Health system spending on incident chronic myeloid leukemia in chronic phase [CML-CP] after generic imatinib becomes available is the subject of great interest among patients, physicians and payers,” Rena Conti, PhD, assistant professor in the departments of pediatrics and public health sciences at The University of Chicago, and colleagues wrote. “Loss of patent exclusivity opens the market to potential competition from multiple manufacturers.”
Generic imatinib is currently available in Canada and expected to be introduced in the United States and Europe during the first quarter of 2016, according to study background.
The price of generic imatinib in Canada is currently 18% to 26% lower than the branded drug price.
Conti and colleagues conjectured that an “imatinib-first” treatment strategy — in which newly diagnosed patients with CML-CP who receive initial treatment with generic imatinib, followed by dasatinib (Sprycel, Bristol-Myers Squibb) or nilotinib (Tasigna, Novartis) — would be more cost-effective than a physicians’ choice strategy of first-line treatment with any one of the three TKIs.
The researchers constructed Markov models to compare the 5-year cost-effectiveness of imatinib-first vs. physicians’ choice treatment strategies from a commercial payer standpoint. The models assumed 3% annual discounting (2013 U.S. dollars).
Further, researchers conducted a systematic review of clinical trial results to construct the models’ clinical endpoint of 5-year OS. They estimated per-person spending on incident CML-CP using MarketScan claims data from 397 patients.
Cost per quality-adjusted life-year (QALY) served as the primary measure. Outcomes were interpreted based on a willingness-to-pay threshold of $100,000 per QALY.
Branded imatinib had a similar average per-person cost of treatment ($79,000 per year) to dasatinib and nilotinib ($87,000-$92,000 per year).
However, imatinib had a lower mean annual cost of the drug itself ($59,000) than dasatinib ($76,000) or nilotinib ($75,000).
Following the end of imatinib’s patent exclusivity, the total cost of imatinib-based treatment was expected to decrease to $46,000 per year.
Overall, initiating treatment with generic imatinib and the physicians’ choice treatment strategy both met the willingness-to-pay threshold compared with a no-alternative-treatment option.
Compared with physicians’ choice, imatinib-first strategy yielded a 0.1 decrement in QALYs (3.87 vs. 3.97), but a savings of $88,343 to payers over 5 years ($277,401 vs. $365,744).
Based on 12-month complete cytogenetic responses, imatinib first cost less over 5 years with slighter fewer QALYs compared with physicians’ choice for an incremental cost-effectiveness ratio of $883,730 per QALY.
Imatinib-first therapy maintained a strong association with cost-effectiveness in multiple sensitivity analyses, with 99.7% of simulations determining an improved net monetary benefit. Additionally, 85.1% identified imatinib-first as cost-effective.
The researchers acknowledged study limitations, including their models’ assumption of perfect patient adherence, which may not reflect actual adherence rates. Further, the study did not employ a lifetime time horizon and lacked data on additional TKI switching among patients.
“In 2016, we anticipate that the per-person, per-month cost of imatinib will drop 60% to 90% once it loses patent protection, while second-generation TKIs dasatinib and nilotinib will hold their high costs steady,” Conti and colleagues wrote. “From a U.S. payer perspective, imatinib will be the cost-effective initial treatment strategy for CML-CP, compared with dasatinib and nilotinib.” – by Cameron Kelsall
Conti reports no relevant financial disclosures. Please see the full study for a list of all other researchers’ relevant financial disclosures.