Suramin is a polyanionic compound whose mechanism of action is unknown. It is normally used in the treatment of African trypanosomiasis. It is currently being studied as a treatment for cancer.
One research study (1) discussed suramin and its effectiveness against cancer. In vitro and in vivo studies have been done on the substance. They revealed that suramin blocks the growth of pancreatic cells and blocks the blood vessel formation to the tumor (this is also called angiogenesis). In the study, the researchers mixed suramin with five different pancreatic cell lines.
It found that suramin was able to block the growth of the pancreatic cells and decreased their viability. Because this particular study was done in vitro (outside of the body), more research needs to be done on human subjects to see if suramin works on real patients with cancer.
Source: 1.Bhargava S, et al. Suramin inhibits not only tumor growth and metastasis but also angiogenesis in experimental pancreatic cancer. J Gastrointest Surg. 2007 Feb;11(2):171-8.