Drug aimed at choking tumor blood vessels fails
By Ransdell Pierson
NEW YORK, Feb 8 (Reuters) - Pharmacia Corp. (NYSE:PHA - news) on Friday said a key experimental cancer drug obtained in its $650 million purchase of biotech firm Sugen had proved ineffective, a setback for medicines meant to starve tumors by shutting off their blood supply.
The Peapack, New Jersey-based firm said an analysis of a late-stage trial showed the drug, called SU5416, was not effective among patients with colorectal cancer that had spread to other parts of the body.
Pharmacia said it was also ending studies of the drug in a wide range of other tumors, including lung, breast and AIDS-related Kaposi's sarcoma.
The intravenous medicine was the crown jewel of Sugen, the California biotech firm Pharmacia bought in 1999 that developed the synthetic compound. It is designed to block receptors for one of the hottest targets in oncology, a protein called vascular endothelial growth factor, or VEGF.
Tumors send out bits of VEGF as messengers to nearby blood cells, ordering them to start building blood vessels that can deliver vital supplies of oxygen and nutrients to tumor cells.
By blocking receptors for the protein, which are located on the surface of endothelial blood cells, Pharmacia hoped the drug would choke off the blood supply to tumor cells and thereby kill them.
``We found out SU5416 didn't work, and now we need to find out why,'' Dr. Lee Rosen, a UCLA oncologist who helped lead the Phase III trials, said in an interview.
But Rosen said he remains as optimistic as ever about the prospects for drugs that stop blood vessel growth to tumors, or so-called ``anti-angiogenesis'' medicines, including pill formulations of two earlier-stage Pharmacia compounds that will continue to be tested.
ALL EYES ON AVASTIN
The newer Pharmacia treatments target VEGF as well as the proteins bFGF and PDGF, which are also members of the large kinase family of proteins that transmit signals between cells.
``Although SU5416 failed, it's given us a better idea how to attack the VEGF target. Maybe we'll find out that these kinds of drugs will work better in combination with other types of cancer therapies or that they will work better in patients whose cancers are less advanced,'' he added.
About 60 clinical trials of anti-angiogenesis drugs are now under way, taking aim at over a dozen different molecular targets. But the most promising target remains VEGF and its receptor, according to Dr. William Li, president of the nonprofit Angiogenesis Foundation based in Cambridge, Massachusetts.
``The trial of SU5416 was stopped because the drug was not effective for the overall group of patients tested, but some patients showed striking benefits,'' Li said, adding the study of the Pharmacia medicine was not stopped because of safety issues.
Li said all eyes will now turn to Genentech Inc's (NYSE:DNA - news) drug against VEGF, called Avastin, a monoclonal antibody being tested in Phase III trials for breast, colorectal and lung cancer as well as for kidney cancer.
Other promising anti-angiogenesis drugs in late-stage development include Celgene Corp's (NasdaqNM:CELG - news) Thalomid (thalidomide) for multiple myeloma and AEterna Laboratories Inc's (Toronto:AEL.TO - news) Neovastat for lung and kidney cancer.
Shares of Pharmacia closed up 91 cents to $38.41 on Friday, while Genentech rose $1.36 to $48.25, both on the New York Stock Exchange. (Additional reporting by Jed Seltzer) |
