The use of generic docetaxel instead of branded docetaxel appears to be associated with a significantly higher event rate of neutropenia, as well as increased healthcare costs, during the 6 months following drug initiation, according to a US Oncology Research study that compared resource utilization and costs.1
The study authors found that breast cancer patients treated with generic docetaxel were about 40% more likely to have a medical claim for neutropenia, relative to branded docetaxel treatment. This cost the healthcare system an additional $9000 per patient, reported Stephen Jones, MD, and colleagues at the American Society of Clinical Oncology 2014 annual meeting.
Before and after its approval in March 2011 in the United States, generic docetaxel has raised some concerns. It has been reported that 90% of the generic docetaxel formulations contain an insufficient amount of active drug, high levels of impurities, or both, which can affect both efficacy and safety.2
The authors compared the disease burden and resource utilization of 1955 breast cancer patients treated with the 2 taxanes between April 2011 and June 2012. The retrospective inception cohort study used the Clinformatics DataMart national healthcare claims database, which contains clinical diagnoses, therapeutic procedures, pharmacy dispensing records, and healthcare resource utilization and expenditures from a large US national health insurer.
The study examined emerging differences between generic and branded formulations during the 6 months after docetaxel initiation by using a hierarchical mixed effects model for adjustment of patient characteristics during the 6 months prior to starting the drug.
The final analysis included 360 patients whose baseline characteristics were similar, including use of anthracyclines, cyclophosphamide, and growth factors, as well as comorbidities and the occurrence of prior neutropenia.
More Problems With Generics at 6-Month Follow-up
During the 6-month follow-up period, the generic docetaxel cohort showed a higher rate of healthcare claims for neutropenia (67.3% vs 48.9%; P < .01) and malaise and fatigue (22.4% vs 13.7%; P < .05) compared with the branded docetaxel cohort. However, the branded cohort had higher rates of nausea and vomiting (43.5% vs 29.6%; P = .02) than the generic cohort.
The following baseline variables were adjusted for the estimation of neutropenia: age, baseline neutropenia, inpatient admission, total healthcare costs, adjuvant therapy, comorbidities, use of granulocyte colony-stimulating factor (G-CSF) and fosaprepitant, and number of treatment cycles. Fosaprepitant, which is indicated for the prevention of delayed vomiting, can cause neutropenia (<1%).
After these adjustments, the rate of neutropenia remained higher with generic than with branded docetaxel (73.9% vs 52.8%; P < .01), even after accounting for history of neutropenia and baseline use of G-CSF or fosaprepitant.
In addition, the generic group used more fosaprepitant at follow-up than the branded group (54.1% vs 30.2%; P < .01). Fosaprepitant use increased the odds of developing neutropenia almost 2.5-fold among generic docetaxel users versus those using the branded drug (P = .03); in the absence of fosaprepitant, neutropenia was 1.4 times higher in the generic group, but this was not statistically significant (P = .31).
Further investigation showed that the difference in neutropenia between generic and branded docetaxel (58.4% vs 35.4%; P = .003) was observed only in patients without a history of neutropenia, whereas there was no between-group difference seen in patients with a prior diagnosis of neutropenia at baseline, in which case the risk was approximately 98% regardless of drug used.
Generic Costs Were Actually Higher
Excluding the cost of branded docetaxel, the mean outpatient cost after initiating treatment was significantly higher for generic docetaxel in both the unadjusted model and the model adjusted for age, comorbidities, inpatient admissions, total costs, and adjuvant therapy at baseline.
In the unadjusted model, the mean cost was $59,177 for the generic cohort and $50,243 for the branded cohort (P = .009), and the cost remained significantly higher after adjustments for baseline healthcare costs, inpatient admissions, and other baseline patient characteristics ($54,282 vs $46,698; P = .03). The mean total healthcare costs after initiating treatment were $83,982 with generic docetaxel and $74,832 with branded docetaxel (P = .05) in the unadjusted model and $76,454 versus $70,736, respectively (P = .22) in the adjusted model.
“The cost differential seems more than offsetting the potential difference in acquisition costs relative to the branded docetaxel,” the authors suggested in a poster.
William Sikov, MD, of Brown University in Providence, Rhode Island, commented while viewing the poster that he found the results interesting and somewhat surprising. He said that he is not aware of whether the patients in his center receive branded or generic products but that he has had some concerns and has often questioned whether generic products may, indeed, be equivalent.
“At times, I have tried to influence the pharmacy to buy a brand name, when the cost differential is minimal, but have been told that I am not allowed [to request that],” he said. “I wonder if the pharmacokinetics are really the same? We are given assurances by the FDA, but we don’t know how extensively they are really tested.”
References
- Jones SE, Liao L, Xiao Z, et al. Resource utilization in patients with breast cancer treated with generic versus branded docetaxel. J Clin Oncol. 2014;32(15 suppl):1015. Presented at: 50th Annual Meeting of the American Society of Clinical Oncology; May 30-June 3, 2014; Chicago, IL. Abstract 1015.
- Vial J, Cohen M, Sassiat P, et al. Pharmaceutical quality of docetaxel generics versus originator drug product: a comparative analysis. Curr Med Res Opin. 2008; 24(7):2019-2033.