We are too readily seduced by what is going on in the blood in CLL. The real deal is what is happening in the lymph nodes. Like in other cancers, a major factor in the progression of the disease is the formation of new blood vessels. In last week's Blood a paper from Italy explores the relationship between blood levels of Angiopoietin-2 and prognosis. Angiopoietin-2 is a glycoprotein which destabilizes blood vessels causing them to revert to a more plastic state and making them more succeptible to the effect of vascular endothelial growth factor (VEGF). It is secreted by CLL cells, especially those that are CD38 positive. unsurprisingly, this paper finds that high levels of Angiopoietin-2 correlate with a poor prognosis.
My friend and colleague, Steve Devereux, suggested to me a couple of years ago that CLL might benefit from treatment with Avastin. Alas, he couldn't raise a grant to study the question, but this is further evidence that he may have been right.