Open-Label, Randomized, Multicenter, Phase III Study Comparing Oral Paclitaxel Plus Encequidar Versus Intravenous Paclitaxel in Patients With Metastatic Breast Cancer.

PURPOSE: Intravenous paclitaxel (IVpac) is complicated by neuropathy and requires premedication to prevent hypersensitivity-type reactions. Paclitaxel is poorly absorbed orally; encequidar (E), a novel P-glycoprotein pump inhibitor, allows oral absorption. METHODS: A phase III open-label study comparing oral paclitaxel plus E (oPac + E) 205 mg/m2 paclitaxel plus 15 mg E methanesulfonate monohydrate 3 consecutive days per week versus IVpac 175 mg/m2 once every 3 weeks was performed. Women with metastatic breast cancer and adequate organ function, at least 1 year from last taxane, were randomly assigned 2:1 to oPac + E versus IVpac. The primary end point was confirmed radiographic response using RECIST 1.1, assessed by blinded independent central review. Secondary end points included progression-free survival (PFS) and overall survival (OS). RESULTS: Four hundred two patients from Latin America were enrolled (265 oPac + E, 137 IVpac); demographics and prior therapies were balanced. The confirmed response (intent-to-treat) was 36% for oPac + E versus 23% for IVpac (P = .01). The PFS was 8.4 versus 7.4 months, respectively (hazard ratio, 0.768; 95.5% CI, 0.584 to 1.01; P = .046), and the OS was 22.7 versus 16.5 months, respectively (hazard ratio, 0.794; 95.5% CI, 0.607 to 1.037; P = .08). Grade 3-4 adverse reactions were 55% with oPac + E and 53% with IVpac. oPac + E had lower incidence and severity of neuropathy (2% v 15% > grade 2) and alopecia (49% v 62% all grades) than IVpac but more nausea, vomiting, diarrhea, and neutropenic complications, particularly in patients with elevated liver enzymes. On-study deaths (8% oPac + E v 9% IVpac) were treatment-related in 3% and 0%, respectively. CONCLUSION: oPac + E increased the confirmed tumor response versus IVpac, with trends in PFS and OS. Neuropathy was less frequent and severe with oPac + E; neutropenic serious infections were increased. Elevated liver enzymes at baseline predispose oPac + E patients to early neutropenia and serious infections (funded by Athenex, Inc; ClinicalTrials.gov identifier: NCT02594371).

Biosimilar Versus Originator Pegfilgrastim for Preventing Chemotherapy-Induced Neutropenia: A Phase III Randomized, Multicenter, Evaluator-Blinded, Noninferiority Study.

PURPOSE: This study evaluated the efficacy, safety, and immunogenicity of biosimilar pegfilgrastim (PegFilBS) and originator pegfilgrastim (PegFilOR) in patients with stage 2-4 breast cancer. METHODS: This phase III randomized, multicenter, evaluator-blinded, noninferiority study recruited women with stage 2-4 breast cancer in Argentina who were scheduled to receive chemotherapy. Stratification was based on the breast cancer stage. The primary end point was the duration of severe neutropenia (DSN, noninferiority margin: 1 day) in the first chemotherapy cycle. Secondary end points assessed were incidence of severe neutropenia, grade 3 neutropenia, febrile neutropenia, infections, postchemotherapy hospitalization and duration, and the incidence of adverse drug reactions (ADRs). RESULTS: A total of 120 patients were randomly assigned to receive PegFilBS (58 patients) or PegFilOR (62 patients). Severe neutropenia occurred in 52 of 283 cycles (18.4%) for 27 patients who received PegFilBS and in 48 of 297 cycles (16.2%) for 20 patients who received PegFilOR (P = .48). During the first cycle, severe neutropenia occurred in 16 patients who received PegFilBS (DSN: 0.78 ± 1.53 days) and in 11 patients who received PegFilOR (DSN: 0.53 ± 1.25 days; 95% CI, -0.26 to 0.76 days). In the intention-to-treat analysis, the mean DSN values were 0.90 ± 1.79 days for the PegFilBS group and 0.50 ± 1.21 for the PegFilOR group (95% CI, -0.15 to 0.95 days). No significant differences were observed for the secondary efficacy end points. Three patients experienced seven ADRs in the PegFilBS group while 10 patients experienced 31 ADRs in the PegFilOR group. The most common ADR was myalgia. CONCLUSION: Relative to PegFilOR, PegFilBS provided noninferior efficacy outcomes in Argentinian women with stage 2-4 breast cancer who were treated using myelosuppressive chemotherapy.