Filgrastim, fibrinolysis, and neovascularization

Segmental recanalization of chronically occluded arteries was observed in patients with chronic limb‐threatening ischemia (CLTI) treated with Filgrastim, a granulocyte colony stimulating factor, every 72 h for up to a month, and an infra‐geniculate programmed compression pump (PCP) for 3 h daily. Molecular evidence for fibrinolysis and neovascularization was sought. CLTI patients were treated with PCP alone (N = 19), or with Filgrastim and PCP (N = 8 and N = 6, at two institutions). Enzyme‐Linked Immunosorbent Assay was used to measure the plasma concentration of plasmin and of fibrin degradation products (FDP), and the serum concentration of proteins associated with neovascularization. In the PCP‐alone group, blood was sampled on Day 1 (baseline) and after 30 days of daily PCP. In the Filgrastim and PCP group, blood was drawn on Day 1, and 1 day after the 5th and the 10th Filgrastim doses. Each blood draw occurred before and after 2 h of supervised PCP. Significant (p < 0.01) PCP independent increases in the plasma concentration of plasmin (>10‐fold) and FDP (>5‐fold) were observed 1 day after both the 5th and the 10th Filgrastim doses, compared to Day 1. Significant (p < 0.05) increases in the concentration of pro‐angiogenic proteins (e.g., HGF, MMP‐9, VEGF A) were also observed. Filgrastim at this novel dosimetry induced fibrinolysis without causing acute hemorrhage, in addition to inducing a pro‐angiogenic milieu conducive to NV. Further clinical testing is warranted at this novel dosimetry in CLTI, as well as in other chronically ischemic tissue beds. Trial registration. https://clinicaltrials.gov/ct2/show/NCT02802852.