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Table 4 Clinical trials of ixabepilone in drug-resistant metastatic breast cancer

From: Chemotherapy resistance in metastatic breast cancer: the evolving role of ixabepilone

Study Population Evaluable for efficacy/enrolled Pretreatment characteristics Activity
Ixabepilone monotherapy
Trial 009, phase II [88] Resistant to taxane; prior treatment with anthracycline-based regimena 49/49 All had received ≥1 prior taxane-based regimen (31 % had ≥2 regimens); 98% had a taxane-containing regimen as their most recent MBC therapy, and 73% had progressed within 1 month of the last administered taxane dose ORR 12%; 41 % stable disease
Median DOR 10.4 months
Median TTP 2.2 months (95% CI, 1.4 to 3.2 months)
Median OS 7.9 months (95% CI, 6.1 to 14.5 months)
Trial 081, phase II [89] Resistant to an anthracycline, a taxane, and capecitabine 113/126 77% with visceral disease in liver and/or lung; 88% had completed ≥2 prior chemotherapy regimens for MBC, 48% had ≥3 lines ORR 11.5%; 50% stable disease
Median DOR 5.7 months (95% CI, 4.4 to 7.3 months)
Median PFS 3.1 months (95% CI, 2.7 to 4.2 months)
Median OS 8.6 months (95% CI, 6.9 to 11.1 months)
Ixabepilone/capecitabine combination
Trial 031, phase II [90] Anthracycline-pretreated or resistant and taxane-resistantb 50/62 72% had baseline visceral metastases, 43% had ≥2 prior chemotherapy regimens in the metastatic setting for MBC ORR 30%c; 32% stable disease
Median time to response 6 weeks (range, 5 to 14 weeks)
Median DOR 6.9 months (95% CI, 4.3 to 9.7 months)
Trial 046, phase III [92] Pretreated with or resistant to anthracyclines and resistant to taxanesd 737/752 65% had ≥3 metastatic disease sites; 48% had received ≥1 prior regimen for MBC; 85% had progressed on prior taxane therapy for metastatic disease ORR 34.7% vs. 14.3%
Median DOR 6.4 months vs. 5.6 months
Median PFS 5.8 months vs. 4.2 months; hazard ratio = 0.75 (95% CI, 0.64 to 0.88)e
  1. MBC, metastatic breast cancer; ORR, overall response rate; DOR, duration of response; TTP, time to progression (months); CI, confidence interval; OS, overall survival; PFS, progression-free survival. aPatients had progressed within 4 months of taxane therapy (6 months, if adjuvant therapy only) and had a taxane as their last chemotherapy regimen. bPatients were ineligible if they had received more than three prior chemotherapy regimens for metastatic disease. cAll responders had extensive metastatic disease at baseline. dResistance to anthracycline and taxane is defined as tumor progression during treatment or within 3 months of the last administered dose in the metastatic setting, or recurrence within 6 months in the neoadjuvant or adjuvant setting. This was subsequently revised to include recurrence within 4 months of the last administered dose in the metastatic setting or 12 months in an adjuvant setting. e P = 0.0003.