Chemotherapy-Bevacizumab Combo Treatment Increases Risk of Arterial Blood Clots
Bevacizumab – popularly marketed as Avastin® - was the first USFDA-approved biological therapy designed to inhibit the formation of new blood vessels in tumors (angiogenesis inhibitor).
The bevacizumab-chemotherapy combination has been found to survival in patients with metastatic colorectal and non–small-cell lung cancer, though previous studies have suggested that patients on this combo treatment are at an increased for arterial blood clots.
But now, treatment with chemotherapy and bavacizumab has been found to be associated with a greater risk of blood clots in patients’ arteries compared to treatment with bevacizumab alone.
As published online on August 7 in the Journal of the National Cancer Institute:
Among patients treated with the combination therapy, 3.8 percent experienced blood clots in their arteries, compared with 1.7 percent of patients on chemotherapy alone.
There was no statistically significant difference in the incidence of blood clots in veins.
Risk factors for blood clots in both arteries and veins included previous blood clots and older age (65 or older.)
Source: EurekAlert
Tags: angiogenesis-inhibitor, arterial-blood-clots, bevacizumabRelated Stories
POSTED IN: ~ Anti-cancer treatments ~
1 opinion for Chemotherapy-Bevacizumab Combo Treatment Increases Risk of Arterial Blood Clots
Gregory D. Pawelski
Sep 15, 2007 at 9:18 pm
An interesting caveat about Avastin
Anti-angiogenesis drugs work by blocking the activity of VEGF to prevent the growth of new capillaries into the tumor and thereby sustain tumor growth. VEGF causes angiogenesis by attaching to special receptors, and this action starts a series of chemical reactions inside the cell.
Avastin (bevacizumab) directly binds to VEGF to directly inhibit angiogenesis. Within 24 hours of VEGF inhibition, endothelial cells have been shown to shrivel, retract, fragment and die by apoptosis. Tumors which secrete relatively low levels of VEGF might be more susceptible to an agent like Avastin which works by blocking VEGF (Avastin “sensitive” tumors). It potently inhibits the formation of new blood vessels.
There is an interesting caveat about Avastin which deals with colon cancer - gastrointestinal perforations. If Avastin is given within at least 28 days following major surgery (or before), it results in an abscess formation. This is due to the impaired wound healing induced by Avastin.
By Avastin working like it’s supposed to work, not only does it cut off blood supply to the tumor, it also cuts off blood supply to the colon entirely causing the tissue to die. Avastin can cause you to loose your colon. What’s distubring is oncologists’ comment that this is common with Avastin, but is never mentioned until it is too late.
Most bowel perforations with Avastin have been in cases where there is tumor going right through the wall of the colon. Avastin causes the tumor to melt away, leaving a hole. With Avastin, the tumor dissolves, but scar tissue won’t form because it can’t make a blood supply.
The same thing applies to bowl perforations with Avastin in advanced ovarian cancer. Advanced ovarian cancer commonly involves bowel walls. The problem is a direct result of the drug’s ability to kill tumor cells that have replaced healthy bowel tissue, leading to a dead area that then perforates.
With conventional chemotherapy, as the tumor melts away, new connective tissue forms a patch. But Avastin can inhibit the growth of capillaries into newly forming tissue, as well as in tumor tissue. If one does not have any known bowel involvement, one would probably be okay.
Many of these new “targeted” therapies often get a pass on toxicities because they are just so darn cool (Herceptin and CHF in the adjuvant setting is another example). The problem is that few drugs work the way oncologists think and few of them take the time to think through what it is they are using them for.
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