The Unknown Effects of VEGF-A Inhibition Beyond the rationale presented here and elsewhere that indicates a clinical benefit with the use of IV-TA as well as a scientific selleck chemical Tipifarnib explanation for its enhanced biologic activity in the treatment of ME, there is another important area of interest that is currently being studied with anti-VEGF-A therapy. While there has been a huge advance in our fundamental knowledge of VEGF-A signaling and an unprecedented growth in the utilization of VEGF-A Inhibitors,Modulators,Libraries inhibitors in the clinic, there have been several studies which point to the role of VEGF-A in the survival of a multitude of retinal cell types. In an initial study, administration of IV or systemic VEGF-A antagonists resulted in retinal ganglion cell apoptosis approximately 8 weeks after treatment in a rat model [60].

Independent Inhibitors,Modulators,Libraries follow-up studies showed that endogenous VEGF-A is necessary for M��ller and photoreceptor cell survival, and systemic blockade led to apoptosis of these cell types at 2�C4 weeks after treatment in a mouse model [61]. In another mouse model, subretinal injection of a lentivirus encoding a VEGF-A antagonist Inhibitors,Modulators,Libraries caused significant photoreceptor degeneration at 6 months compared to controls [62]. Lastly, in a very recent study, it was found that a transgenic mouse strain in which the VEGF-A isoforms normally produced by the RPE were ablated developed choriocapillaris degeneration and RPE cell loss, suggesting that VEGF-A carries a survival function in the RPE-choroidal tissues as well as the neural retina [63].

Many groups have been studying whether similar effects occur in patients receiving frequent anti-VEGF-A treatments for age-related macular degeneration. In a small series of patients followed Inhibitors,Modulators,Libraries over Inhibitors,Modulators,Libraries the course of a year after treatment with ranibizumab every month for 3 months followed by as-needed dosing, a significant reduction in the mean retinal arteriolar diameter was observed that stabilized by day 90 and persisted after the study endpoint. In another clinical study, it was found that increased numbers of ranibizumab treatments correlated with specific neural retinal dysmorphic features. In this particular study, the inner segment/outer segment photoreceptor junction was often not visible using optical coherence tomography in patients receiving more frequent ranibizumab administrations, suggesting that retinal damage might occur with increased anti-VEGF-A exposure.

Finally, in a study analyzing the efficacy of IV-TA versus that of IV-B for central retinal vein occlusion, minor differences in BCVA at 1 year were evident, yet ME did resolve with IV-TA and persisted with IV-B, which was significant Batimastat at 6 months and persisted at 1 year [64]. However, in this particular study, final BCVA only differed in that 50% more patients lost 2 or more lines in the IV-B group compared to the IV-TA group.