For Metastatic Breast Cancer, Nab-Paclitaxel Requires Less Growth Factor Support

Caroline Helwick

March 2012, Vol 3, No 2 - Breast Cancer

San Antonio, TX—In a retrospective utilization and cost analysis, nab-paclitaxel (Abraxane) therapy was associated with substantially lower total use of prophylactic colony-stimulating factor (CSF) than docetaxel (Taxotere) and paclitaxel (Taxol) in the treatment of breast cancer. The study was reported at the 2011 San Antonio Breast Cancer Sympo sium by Rex W. Force, PharmD, Professor and Director of Research, Family Medicine and Pharmacy Practice, Idaho State University, and Partner, ImproveRX, LLC, and colleagues. "Although the other taxanes are less expensive than nab-paclitaxel, the difference is almost made up for when considering the total cost of care with CSF support," Dr Force told Value-Based Cancer Care.

It is estimated that $15 billion in total healthcare costs are spent annually on the treatment of breast cancer in the United States, and much of this cost stems from the use of taxanes. Clinically meaningful differences in adverse effects, including rates of neutropenia, may be present among the different drugs. Comparative trials have shown lower rates of grade 3 or 4 neutropenia with nab-paclitaxel compared with docetaxel or paclitaxel. "Docetaxel tends to be much more toxic to the bone marrow, and comparative trials have shown more grade 3 and 4 neutropenia with both docetaxel and paclitaxel than with nab-paclitaxel," Dr Force said. "The costs of managing adverse effects related to neutropenia are likely to be significant," the investigators stated in their poster. The study was conducted to determine if differences exist in the rates of CSF use for prophylaxis and treatment in women receiving taxane-based chemotherapy for metastatic breast cancer and to compare the costs of this use.

Study Details
Investigators used actual paid medical claims from a national commercial payer (Ingenix Consulting). The data-set included more than 56 million procedure claims from more than 350,000 unique patients with cancer treated between 2006 and 2009. CSF use was defined as prophylactic (days 0-5 posttaxane administration), treatmentrelated (days 6-21 posttaxane administration), or nontaxane-associated (all other CSF administration). In calculating daily CSF costs, investigators controlled for age, comorbidity score, prior chemotherapy use, and concurrent chemotherapy use. The primary outputs of the analyses were CSF use and daily per-patient CSF costs adjusted for those variables. The study included 2599 patients receiving docetaxel, 1643 receiving paclitaxel, and 261 receiving nab-paclitaxel. The average number of days receiving a taxane were 91, 88, and 156, respectively. Dr Force suggested that patients may be receiving more nabpaclitaxel because of its better tolerability. "We have shown in previous studies that patients with nab-paclitaxel actually have less neutropenia, and neutropenia is one of the main reasons for discontinuing the taxanes," he pointed out.

Mean Per-Patient Unadjusted CSF Costs.
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Less CSF Use, Lover Treatment Costs with Nab-Paclitaxel
Overall, more women receiving docetaxel and paclitaxel received CSF support compared with women treated with nab-paclitaxel. Most of this was in the form of prophylaxis; the use of treatment-related CSF was not different between the taxane groups, Dr Force reported. Any use of CSF was documented for 76% of the docetaxel cohort, 50% of the paclitaxel cohort, and 37% of the nabpaclitaxel cohort (P <.05 for all comparisons). Prophylactic use was record ed for 73%, 47%, and 33% of patients, respectively. Treatment-related CSF was administered to 16% of patients receiving docetaxel, 11% receiving paclitaxel, and 15% receiving nab-paclitaxel (P <.05 for docetaxel vs paclitaxel). Nontaxane-associated CSF was used by 26%, 31%, and 10% of patients, respectively (P <.05 for all comparisons). Prophylactic CSF administration represented approximately 70% of overall CSF expenditures. The mean per-patient unadjusted CSF costs are shown in the Table. Median daily CSF expenditures were lower for nab-paclitaxel ($46.24) compared with docetaxel ($176.81), which was 3.8-fold higher, and paclitaxel ($127.71), which was 2.8-fold higher than for nab-paclitaxel, he said. "The manufacturer of nab-paclitaxel asserts that the formulation of this product has a different pharmacokinetic and pharmacodynamic profile that translates into less neutropenia. What we have seen, in this claims dataset, is that there is, in fact, far less spent in terms of CSF support for patients getting nab-paclitaxel," Dr Force said in the interview. "Nab-paclitaxel is more expensive in drug acquisition costs, but the total cost of care in terms of managing a sick patient is small," he said. "The cost of CSF support is a good chunk of this."