Kosaka, Y., Rai, Y., Masuda, N., Takano, T., Saeki, T., Nakamura, S., . . . Tamura, K. (2015). Phase III placebo-controlled, double-blind, randomized trial of pegfilgrastim to reduce the risk of febrile neutropenia in breast cancer patients receiving docetaxel/cyclophosphamide chemotherapy. Supportive Care in Cancer, 23, 1137–1143. 

To determine the extent to which pegfilgrastim reduces the risk of febrile neutropenia (FN) in Japanese women with early-stage breast cancer receiving docetaxel and cyclophosphamide (DC) chemotherapy

Pegfilgrastim at 3.6 mg or a placebo was administered subcutaneously on day 2 (at least 24 hours after DC chemotherapy) of a 21-day cycle. The study compared the incidence of FN between the pegfilgrastim and placebo cohorts. The incidence of FN during the first cycle of chemotherapy, incidence of hospitalization related to FN, incidence of grade 4 neutropenia, and percentage of patients who received antibiotics as a result of FN also were tracked.

• N = 346
• MEDIAN AGE = 50–51 years (range = 26–69 years)
• FEMALES: 100%
• KEY DISEASE CHARACTERISTICS: Stages I–III primary invasive breast cancer
• OTHER KEY SAMPLE CHARACTERISTICS: Not applicable

• SITE: Multi-site  
• SETTING TYPE: Not specified  
• LOCATION: Japan

• PHASE OF CARE: Active antitumor treatment

Randomized, double-blinded, controlled trial using pegfilgrastim versus a placebo

FN was defined as an absolute neutrophil count < 500 and an axillary temperature at or above 37.5°C on the same day or the following day. Complete blood counts were checked on days 1, 2, 8, 11, and 15 during cycle 1 and on days 1, 2, 8, and 11 of subsequent cycles. Axillary body temperature was measured daily.

Patients treated with pegfilgrastim experienced a significantly lower incidence of FN (1.2%) compared to those who received a placebo (68.8%; p < 0.001). The measurement of secondary endpoints also revealed significant differences between the two groups. None of the patients in the pegfilgrastim group required hospitalization for FN whereas 6.9% of the placebo group did (p < 0.001). Patients who received pegfilgrastim were significantly less likely to require antibiotics to treat FN (0.6%) than those in the control group (56.6%; p < 0.001). During the first chemotherapy cycle, only one patient (0.6%) in the pegfilgrastim cohort developed FN compared to greater than half (57.8%) of the placebo group (p < 0.001). Only 4% of the pegfilgrastim group developed grade 4 neutropenia during chemotherapy whereas all of the placebo group developed this grade (p < 0.001).

Previous studies demonstrated the value of pegfilgrastim in significantly reducing FN in European and North American patients with breast cancer receiving chemotherapy with docetaxel. This study confirmed the efficacy of pegfilgrastim (using a dose of 3.6 mg) for use in Japanese female patients with breast cancer receiving DC chemotherapy. These results suggest that additional studies should be designed to determine if the lower pegfilgrastim dose of 3.6 mg is not inferior to the standard 6 mg dose.

• Findings not generalizable
• Other limitations/explanation: This study used pegfilgrastim at 3.6 mg, not the 6 mg that is the standard dose in the United States and Europe. The authors chose 3.6 mg for their study population because this dose has been demonstrated to be effective in reducing the incidence of FN following docetaxel, doxorubicin, and cyclophosphamide chemotherapy in Japanese patients.

The focus of this study was to demonstrate pegfilgrastim's efficacy in female Japanese patients with breast cancer, and it used a smaller pegfilgrastim dose than is commonly prescribed in the United States or Europe. Additional study is warranted to determine the appropriate dosage of pegfilgrastim for this particular population.