Neulasta Reduces Risk of Fever and Low White Blood Cell Count in Women Taking Taxotere

Reviewed study: "Neulasta Reduces Risk of Fever and Low White Blood Cell Count in Women Taking Taxotere" by C. L. Vogel et al., Journal of Clinical Oncology, February 20, 2005

Background and importance of the study: A potentially serious side effect of chemotherapy is febrile neutropenia, a fever caused by a lower-than-normal white blood cell count. White blood cells are part of your immune system. The two kinds of immune cells that are most helpful in protecting you against infection are neutrophils (mature white blood cells) and bands (brand new ones that are not quite fully mature). These cells are very sensitive to chemotherapy, and their counts drop when you have chemotherapy. With fewer immune cells to protect you, your risk of infection increases.

If you develop a fever of 100.5 Fahrenheit or higher and your white blood cell counts are low (under 1,000 neutrophils and bands combined), then your doctor will assume that you have an infection. You will be hospitalized to receive intravenous (IV) antibiotics and medicine to help build up the immune cell counts.

Neulasta (chemical name: pegfilgrastim), also known as granulocyte colony-stimulating factor or "growth factor," can reduce the risk of getting febrile neutropenia. Neulasta is given once with every chemotherapy cycle by injection under the skin. This drug is closely related to another medication, Neupogen (chemical name: filgrastim), given every day for about a week with each chemotherapy cycle, either as an injection or intravenously. Most people prefer Neulasta over Neupogen because it requires fewer injections.

Every chemotherapy regimen is associated with some risk of febrile neutropenia. If that risk is 40% or higher, then Neulasta is recommended.

The study reviewed here looked at women taking Taxotere (chemical name: docetaxel), a chemotherapy that is associated with a 10% to 20% risk of febrile neutropenia. The researchers wanted to see if Neulasta could reduce the risk of febrile neutropenia enough to warrant recommending its use in this lower-risk group.

Study design: This Phase III study was conducted by researchers from the United States, Poland, Russia, and Mexico. The researchers looked at 928 women at 88 sites in Europe and North America.

The women in the study had these characteristics:

• About half were older than 52 and half were younger.
• 66% were white, 31% were Hispanic, and 3% were of another race.
• White blood cell counts within the normal range at the start of the study.
• 30% had had radiation therapy in the previous two years.
• 65% had had chemotherapy in the previous two years.
• 62% had metastatic (advanced) breast cancer.
• 94% were either fully active despite their cancer or able to carry out light or office work.

The women were randomly assigned to one of two groups, each receiving a 6-mg injection the day after receiving chemotherapy with Taxotere. In the first group (465 women) the injection was a placebo (dummy). In the second group (463 women) the injection was Neulasta. This was a double-blind study, which means that neither the researchers nor the women being treated knew who was getting Neulasta and who was getting a placebo.

The women received up to four cycles of Taxotere given every three weeks. Anyone who developed febrile neutropenia was given Neulasta, regardless of which group they were in.

Results: The researchers found that febrile neutropenia happened less frequently (1%) in the women who got Neulasta after their first cycle of chemotherapy than in those who got the placebo (17%). These results were significant, meaning they were most likely due to the drug, rather than just to chance.

Febrile neutropenia happened less often in the Neulasta group than in the placebo group after the other three cycles of chemotherapy, too. But those differences were not significant (it's possible that they were due to chance).

The majority (about 66%) of all febrile neutropenia in the placebo group happened during the first chemotherapy cycle.

The women who received Neulasta also needed fewer intravenous antibiotic treatments for febrile neutropenia than those who received the placebo (2% compared to 10%). Those in the Neulasta group were also hospitalized less frequently due to febrile neutropenia than those in the placebo group (1% compared to 14%). These results were seen after the first cycle of chemotherapy treatments and were statistically significant (not just due to chance).

Bone pain is a known side effect of Neulasta. About 31% of those in the Neulasta group (146 women) and 27% of those in the placebo group (126 women) had bone pain. Most reported that it was mild to moderate, but 2% of those in the Neulasta group (11 women) and 1% of those in the placebo group (6 women) reported severe bone pain.

Conclusions: Women receiving chemotherapy with Taxotere who took Neulasta were much less likely to develop febrile neutropenia. The relative risk reduction was 94% (a drop from 17% to 1%). Neulasta also decreased febrile neutropenia-related antibiotic IV treatments and hospital stays. The researchers also concluded that giving Neulasta to women getting chemotherapy who have less than a 40% chance of developing febrile neutropenia is justified.

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