Objective To investigate the compatibility of recombinant tissue plasminogen activator (rtPA) and bevacizumab in vitro because during surgery, rtPA or rtPA-induced plasmin may cleave and inactivate bevacizumab.
Methods To simulate the intraoperative range of mixing ratios of rtPA, bevacizumab, and subretinal blood, we calculated the volumes of 12 submacular hemorrhages (SHs) with a spherical cap formula using measurements derived from fundus photographs and spectral-domain optical coherence tomographic images. Bevacizumab was incubated with rtPA or plasmin before gel electrophoresis with Coomassie blue and silver staining. The anti-angiogenetic activity of bevacizumab in the presence of rtPA with or without clotted human blood or of plasmin was quantified by vascular endothelial growth factor–enzyme-linked immunosorbent assay after incubation with the supernatant of porcine retinal pigment epithelium cell cultures.
Results The mean (SD) volume of SH was 28.6 (24.7) mm3 (range, 6.2-94.6 mm3). In sodium dodecyl sulfate–polyacrylamid electrophoresis with Coomassie blue or silver staining, bevacizumab displayed characteristic patterns of protein bands. No additional fragments were detected in co-application of bevacizumab with either rtPA or plasmin. The anti-angiogenetic activity of bevacizumab remained unchanged in co-application with rtPA with or without blood or plasmin.
Conclusions We demonstrated the absence of cleavage or functional inactivation of bevacizumab by rtPA in an in-vitro model of their intraoperative co-application as a treatment of SH.
Clinical relevance In clinical practice, rtPA and bevacizumab can be co-applied as a treatment for neovascular age-related macular degeneration with SH to simultaneously clear SH and reduce choroidal new vessel activity.