Pegylated filgrastim(Bio-Ker s.r.l.)

A number of recombinant protein therapeutic products, such as filgrastim (methionyl granulocyte colony stimulating factor [Met-GCSF] used to boost the immune system in chemotherapy treated cancer patients), and interferon alpha-2 (used for the treatment of various viral infections), have been chemically modified with the addition of a polyethylene glycol (PEG) chain. This modification prolongs residency of the drug in the body and reduces metabolic degradation, which allows less frequent administration of the products. Here we show how NMR spectroscopy methods can assess the higher order structure (HOS) of pegylated-filgrastim (Neulasta®), pegylated interferon-α2a (Pegasys®) pegylated interferon-α2b (PEG-Intron®) purchased from the marketplace. The addition of the PEG moiety effectively doubles the molecular weight of the three products. This presents a significant challenge for the application of NMR techniques. Nevertheless, the results showed that high-resolution spectra could be recorded for two of the three products. Comparison of the spectra of the pegylated protein and the non-pegylated protein shows that the chemical modification did not alter the HOS of these proteins.

To analyze the duration of preventive filgrastim administration as support for chemotherapy and its affecting factors.

Single institutional data from a phase Ⅱ clinical trial and a phase Ⅲ clinical trial of pegylated filgrastim were combined. In the two randomized cross-over trials, patients with previously untreated cancer received two cycles of chemotherapy of the same regimen. In the study group, the patients received a single subcutaneous injection of 100 μg/kg pegylated filgrastim, and in the control group, they received daily subcutaneous injections of 5 μg/kg filgrastim.

In 53 chemotherapy cycles, the median duration of filgrastim administration was (9.57±2.10)d. 83.0% (44/53) of them received filgrastim for 7-11 days. Patients with baseline absolute neutrophil count of <4×10(9)/L or body mass index less than 22 received a longer filgrastim prophylaxis(P<0.05). RESULTS of multivariate analysis showed that the baseline absolute neutrophil count is associated with the time of filgrastim administration(P=0.019). The most common adverse event of rhG-CSF was skeletal pain, generally mild and no treatment-related death occurred.

The median duration of filgrastim support for chemotherapy was 10 days. Patients with lower baseline neutrophil count require a longer filgrastim prophylaxis.

: ClinicalTrials.gov identifier, NCT01285219.