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[1070] Weekly nanoparticle albumin paclitaxel (Abraxane) results in long-term disease control in patients with taxane-refractory metastatic breast cancer.
OShaughnessy JA, Blum JL, Sandbach JF, Savin M, Fenske E, Hawkins MJ.. Baylor-Charles A. Sammons Cancer Center, Dallas, TX; US Oncology, Houston, TX; Texas Oncology, P.A., Austin, TX; Texas Oncology, P.A, Plano, TX; American BioScience, Inc., Santa Monica, CA
Background: Nanoparticle albumin paclitaxel (Abraxane, ABI-007, ABX) is the first biologically interactive composition exploiting a receptor-mediated (gp60) pathway achieving high intracellular tumor concentrations of the active ingredient, paclitaxel. Weekly administration (3 doses, 1 week of rest) of 100 mg/m2 ABX in 106 patients with taxane-refractory metastatic breast cancer (MBC) was active and well tolerated with no grade (GR) 4 nonhematologic toxicities and 91% of patients maintaining full dose with no dose reduction. In that study, overall response rate was 15% (95% CI: 8%-22%), with a 13% probability of being progression-free at 12 months and a 38% probability of survival at 12 months. Since long-term disease control was achieved with this extremely well-tolerated weekly regimen of ABX, we explored the higher dose of 125 mg/m2 in this same patient population.
Methods: In this Phase II study, patients with taxane-refractory, measurable MBC received ABX 125 mg/m2 weekly IV over 30 minutes on days 1, 8, and 15 on a 28-day cycle without premedication. Patients were considered taxane-refractory if they had progressive MBC while receiving paclitaxel, docetaxel, or both; or if they had relapsed within 12 months of adjuvant taxane.
Results: 75 patients enrolled; 74 received treatment. Median age was 53 (range, 33-74); 94% were postmenopausal; median number of metastatic sites was 4 (range: 1-13); 61% had hormone receptor positive MBC; and median number of prior chemotherapy regimens for metastatic disease was 3 (range: 0-5; n=66). 19 patients (26%) had dose reductions, mostly for sensory neuropathy and neutropenia. Treatment-related (TR) GR 4 toxicities were neutropenia (2 patients), anemia (1), thrombocytopenia (1), infection (1), stomatitis/pharyngitis (1), hypokalemia (1), and thrombosis/embolism (1). TR GR3 toxicities for >1 patient were neutropenia (21 patients), sensory neuropathy (8), fatigue (6), nausea (2), diarrhea (2), anorexia (2), anemia (2), thrombocytopenia (2), febrile neutropenia (2), and muscle weakness (2).
Conclusion: ABX 125 mg/m2 administered weekly is well tolerated for this poor prognosis patient population with taxane-refractory MBC. We have demonstrated that 100 mg/m2 is extremely well tolerated and active in this patient population, and the potential risk-benefit of the higher dose (125 mg/m2) awaits efficacy analysis as the data matures.
Wednesday, December 8, 2004 4:30 PM
Poster Session: Treatment: Chemotherapy -- New Drugs and Formulations (4:30 PM-7:00 PM)
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