Randomized phase II trial of three dosing schedules of nanoparticle albumin-bound paclitaxel with bevacizumab as first-line therapy for HER2-negative metastatic breast cancer: An initial interim safety report

1104 Background: Nanoparticle paclitaxel (NP) at 260mg/m 2 every 3 weeks (q3wk) is more effective than standard paclitaxel (P) (Gradishar et al, JCO 2005). Weekly, uninterrupted administration of P is superior to q3wk P in MBC (Seidman et al, Proc ASCO 2004). When added to weekly P as 1 st -line therapy for MBC, bevacizumab (B) improves response rate and progression-free survival (Miller et al, Proc ASCO 2005). We initiated a randomized phase II trial of NP given at 260mg/m 2 q3wk (arm A) vs. 260mg/m 2 q2wk with filgrastim (arm B) vs. 130mg/m 2 weekly, all with B, as 1st-line therapy for patients (pts) with HER2- MBC. Methods: 66 of planned 225 pts have enrolled. After 31 pts had been randomized and treated, investigators concerned about possible differential neurotoxicity requested this early interim safety analysis. Median age is 54 (range 40–78). 83% are post-menopausal and 100% have visceral dominant disease. 68% had prior adjuvant or neo-adjuvant chemotherapy; 35% with taxanes. Results: With 170 cycles delivered (median: 4, range 1–15) 10 dose reductions have been necessary for NP (1 in A, 5 in B, 4 in C). No hypersensitivity reactions or dose interruptions have occurred for NP; 3 doses of B have been held due to hypertension. Significant preliminary antitumor activity has been noted in all arms. One grade 4 toxicity occurred in arm C, hyperglycemia. 15 grade 3 toxicities have been reported across all arms. Pts on arm A have experienced 3 grade 3 toxicities (30%): fatigue, neutropenia, and arthralgia with no grade 3 neurotoxicity. Pts on arm B have had 7 grade 3 toxicities (58%) with 3 pts experiencing grade 3 sensory neuropathy (25%) and others experiencing fatigue, neutropenia, anemia, esophagitis, dyspnea, and ataxia. 5 arm C pts experienced grade 3 toxicities (56%) including diarrhea, dehydration, mucositis, neutropenia, hypokalemia; 2 pts have had grade 3 sensory neuropathy (22%). Conclusions: This early safety analysis does not detect any statistically or clinically significant differences in grade 3 toxicity and all arms continue to accrue. The next protocol-specified safety analysis is expected in early 2007, with mature safety data for 60 pts. Updated results will be presented. [Table: see text]