Dose-dense nab-paclitaxel (nanoparticle albumin-bound paclitaxel) in adjuvant chemotherapy for breast cancer: A feasibility study

594

Background: We sought to evaluate the feasibility of substituting nab-paclitaxel (ABI-007) for paclitaxel as part of “dose-dense” adjuvant sequential doxorubicin / cyclophosphamide (AC) followed by taxane chemotherapy. Patients and Methods: Eligible patients had stage I-III breast cancer receiving adjuvant/neoadjuvant chemotherapy, ANC > 1500, and LVEF > 50%. Patients received AC (60 mg/m2 and 600 mg/m2) every 2 weeks × 4 cycles with G-CSF support, followed by nab- paclitaxel 260 mg/m2 every 2 weeks × 4 cycles. The endpoint was incidence of treatment delay during nab-paclitaxel therapy. Results: 66 women (median age 48 years) were enrolled. Among the first 11 given nab-paclitaxel without G-CSF support, one developed febrile neutropenia, and 4 had nab-paclitaxel treatment delays related to neutropenia (ANC < 1,000). The protocol was amended to require G-CSF support (filgrastim or pegfilgrastim) during nab-paclitaxel. Among the next 55 patients, 3 had febrile neutropenia, none during nab- paclitaxel. In cycles 6–8, nab-paclitaxel was delayed only 6 times (1 neutropenia, 3 hepatic toxicity, 2 patient scheduling); 96% of these cycles were delivered on time. By comparison, 82% of such cycles were delivered on time in a prior institutional study using paclitaxel. In the full cohort, 8 patients had nab-paclitaxel dose reduction, 4 for neuropathy, while other neuropathy was moderate (grade 2, n = 6; grade 3, n=1; grade 4, n=0). Conclusions: Administration of nab-paclitaxel every 2 weeks is feasible but requires G-CSF support. Data comparing nab-paclitaxel dose-delivery, toxicities and quality of life to paclitaxel as seen in prior studies will be presented.

No significant financial relationships to disclose.

Clinical outcomes of ethnic minority women in MA.17: a trial of letrozole after 5 years of tamoxifen in postmenopausal women with early stage breast cancer

BACKGROUND

Aromatase inhibitors are widely employed in the adjuvant treatment of early stage breast cancer. The impact of aromatase inhibitors has not been established in ethnic minority women.

PATIENTS AND METHODS

The purpose of this study was to evaluate the impact of letrozole on minority women in MA.17, a placebo-controlled trial of letrozole following 5 years of tamoxifen in postmenopausal women with early stage breast cancer. Retrospective comparison of disease-free survival (DFS), side effects, and mean changes in quality of life (QOL) scores from baseline between Caucasian and minority women was performed.

RESULTS

Minority (n = 352) and Caucasian (n = 4708) women were analyzed. There was no difference between these groups in DFS (91.6% versus 92.4% respectively for 4 year DFS). Letrozole, compared with placebo, significantly improved DFS for Caucasians (HR = 0.55; P < 0.0001) but not for minorities (HR = 1.39; P = 0.53). Among women who received letrozole, minorities had a significantly lower incidence of hot flashes (49% versus 58%; P = 0.02), fatigue (29% versus 39%; P = 0.005), and arthritis (2% versus 7%; P = 0.006) compared with Caucasians. Mean change in QOL scores for minority women who received letrozole demonstrated improved mental health at the 6-month assessment (P = 0.02) and less bodily pain at the 12-month assessment (P = 0.046).

CONCLUSION

Letrozole improved DFS in Caucasians but a definite benefit in minority women has not yet been demonstrated. Minority women tolerated letrozole better than Caucasians in terms of toxicity. These results need confirmation in other trials of aromatase inhibitors.

NCIC CTG MA.17: Tolerability of letrozole among ethnic minority women

6018

Background: Disease free survival was significantly improved in women receiving letrozole after standard adjuvant tamoxifen in the MA.17 trial. Based on the results of MA.17 and of other trials of aromatase inhibitors in early stage breast cancer, chronic aromatase inhibitor therapy, in postmenopausal women free of breast cancer recurrence, is now being widely employed. We analyzed the toxicity of letrozole according to ethnic status among women enrolled in MA.17. Methods: The chi-square test was used for comparison of rates of side effects between the two groups, Caucasian vs. ethnic minority (defined as all non-Caucasians). In a subset of women, quality of life (QOL) was assessed by the SF-36 Health Survey. Mean change scores in QOL from baseline were compared between groups for summary measures and domains using the Wilcoxon test. Results: 352 minority women and 4,708 Caucasians were enrolled in MA.17, of which 183 minority women and 2,339 Caucasians were randomized to receive letrozole. Caucasians were older than minority women and had a slightly longer duration of treatment with prior tamoxifen. Tumor size and nodal status were not significantly different between the two groups. In women who received letrozole, minority women had significantly lower incidence of hot flashes (49% vs. 58%; p = 0.02), fatigue (29% vs. 39%; p = 0.005), and arthritis (2% vs. 7%; p = 0.006) compared with Caucasians. Mean QOL change scores of SF-36 domains for women who received letrozole were not different but minority women had better mental health at 6 month assessment (p = 0.02) and worse bodily pain at 12 month assessment (p = 0.046). Conclusions: Minority women tolerated letrozole considerably better than Caucasians in the MA.17 trial. These preliminary findings suggest that minority women respond differently to letrozole in terms of toxicity. Recent demonstration of genotypic variations in the aromatase gene in different ethnic groups plus likely pharmacogenomic differences suggests that further research is needed to clarify the clinical outcomes of aromatase inhibition in women of diverse ethnicities. Future research strategies should focus on examining in vivo genotype-phenotype correlations to determine the effects of genetic variation on response to anticancer therapy and on toxicities and end-organ effects.

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Hemolytic uremic syndrome associated with clopidogrel: a case report

Clopidogrel and ticlopidine are antiplatelet agents used in the treatment of patients with cerebrovascular and peripheral vascular disease and to reduce the risk for thrombosis in patients undergoing coronary artery stenting. Ticlopidine has been reported to have major hematologic adverse effects, including neutropenia and thrombotic thrombocytopenic purpura or hemolytic uremic syndrome (HUS). Clopidogrel, an analogue of ticlopidine, was developed because it did not show bone marrow toxic effects in either tissue culture or animal models. In human studies, to date, clopidogrel has been associated with a low incidence of severe neutropenia and no reported cases of thrombotic thrombocytopenic purpura or HUS. For these reasons, clopidogrel has been increasingly used in place of ticlopidine after coronary artery stenting. We report a case of clopidogrel-associated HUS. This observation implicates clopidogrel as a possible causative agent in HUS.