The economic impact of the transition from branded to generic oncology drugs.

Background: Economic evaluations are an integral component of many clinical trials. Costs used in those analyses are based on the prices of branded drugs when they first enter the market. The effect of genericization on the cost-effectiveness (ce) or cost-utility (cu) of an intervention is unknown because economic analyses are rarely updated using the costs of generic drugs. Methods: We re-examined the ce or cu of regimens previously evaluated in Canadian Cancer Trials Group (cctg) studies that included prospective economic evaluations and where genericization has occurred or is anticipated in Canada. We incorporated the new costs of generic drugs to characterize changes in ce or cu. We also determined acceptable cost levels of generic drugs that would make regimens reimbursable in a publicly funded health care system. Results: The four randomized controlled trials included (representing 1979 patients) were cctg br.10 (early lung cancer, adjuvant vinorelbine-cisplatin vs. observation, n = 172), cctg br.21 (metastatic lung cancer, erlotinib vs. placebo, n = 731), cctg co.17 (metastatic colon cancer, cetuximab vs. best supportive care, n = 557), and cctg ly.12 (relapsed or refractory lymphoma, gemcitabine-dexamethasone-cisplatin vs. cytarabine-dexamethasone-cisplatin, n = 619). Since the initial publication of those trials, the genericization of vinorelbine, erlotinib, cetuximab, and cisplatin has taken place or is expected in Canada. Costs of generics improved the ces and cus of treatment significantly. For example, genericization of erlotinib ($1460.25 per 30 days) resulted in an incremental cost-effectiveness ratio (icer) of $45,746 per life-year gained compared with $94,638 for branded erlotinib. Likewise, genericization of cetuximab ($275.80 per 100 mg) produced an icer of $261,126 per quality-adjusted life-year (qaly) gained compared with $299,613 for branded cetuximab. Decreases in the cost of generic cetuximab to $129.39 and $63.51 would further improve the icer to $150,000 and $100,000 per QALY respectively. Conclusions: Genericization of a costly oncology drug can modify the ce and cu of a regimen significantly. Failure to revisit economic analyses with the costs of generics could be a missed opportunity for funding bodies to optimize value-based allocation of health care resources. At current levels, the costs of generics might not be sufficiently low to sustain publicly funded health care systems.

Tamoxifen metabolism predicts drug concentrations and outcome in premenopausal patients with early breast cancer.

Tamoxifen is the standard-of-care treatment for estrogen receptor-positive premenopausal breast cancer. We examined tamoxifen metabolism via blood metabolite concentrations and germline variations of CYP3A5, CYP2C9, CYP2C19 and CYP2D6 in 587 premenopausal patients (Asians, Middle Eastern Arabs, Caucasian-UK; median age 39 years) and clinical outcome in 306 patients. N-desmethyltamoxifen (DM-Tam)/(Z)-endoxifen and CYP2D6 phenotype significantly correlated across ethnicities (R(2): 53%, P<10(-77)). CYP2C19 and CYP2C9 correlated with norendoxifen and (Z)-4-hydroxytamoxifen concentrations, respectively (P<0.001). DM-Tam was influenced by body mass index (P<0.001). Improved distant relapse-free survival (DRFS) was associated with decreasing DM-Tam/(Z)-endoxifen (P=0.036) and increasing CYP2D6 activity score (hazard ratio (HR)=0.62; 95% confidence interval (CI), 0.43-0.91; P=0.013). Low (<14 nM) compared with high (>35 nM) endoxifen concentrations were associated with shorter DRFS (univariate P=0.03; multivariate HR=1.94; 95% CI, 1.04-4.14; P=0.064). Our data indicate that endoxifen formation in premenopausal women depends on CYP2D6 irrespective of ethnicity. Low endoxifen concentration/formation and decreased CYP2D6 activity predict shorter DRFS.