June 6, 2012
Shrinking Tumors in Multiple Cancers
(Ivanhoe Newswire) — Clinical trials have shown promising early results in patients with advanced non-small cell lung cancer, melanoma, and kidney cancer.
Johns Hopkins Kimmel Cancer Center is leading a clinical study testing experimental drugs aimed at restoring the immune system´s ability to spot and attack cancer.“Based on the positive response rates to these drugs and longevity of many of these responses, we believe that new clinical trials should move forward,” quoted Suzanne Topalian, M.D. and professor of surgery and oncology at Johns Hopkins.
Preliminary analysis shows that, among responding patients who were followed were maintained for more than one year in two-thirds of those treated on one trial and in half of those in the other trial. The immune based therapies tested in the two clinical trials aim not to kill cancer cells directly, but to block a pathway that shields tumor cells from immune system components able and poised to fight cancer.
The pathway includes two proteins called programmed death-1 (PD-1), expressed on the surface of immune cells, and programmed death ligand-1 (PD-L1), expressed on cancer cells. When PD-1 and PD-L1 join together, they form a biochemical “shield” protecting tumor cells form being destroyed by the immune system. To make cells more vulnerable to attack by the immune system, investigators tested each of two drugs, BMS-936558, which blocks PD-1, and BMS-936559, which blocks PD-L1. The drugs are given through an IV in an outpatient clinic every two weeks, and patients can remain on the treatment for up to two years.
The PD-1 blocking drug was tested in 296 patients with various advanced cancer who had not responded to standard therapies. Of those patients receiving this therapy, 240 who started treatment by July 2011 were analyzed for tumor response. Significant tumor shrinkage was seen in 18% of non-small cell lung cancer patients, 28% of melanoma patients, and 27% of kidney cancer patients. In this trial, some patients experienced no growth or shrinkage of the tumor for six months or more.
The PD-L1 blocking therapy also showed responses among 207 treated patients. 10% of non-small lung cancer patients, 17% of melanoma patients, and 12% of kidney cancer patients responded.
“The positive results from both drugs give us a good indication that the PD-L1/PD-1 pathway is an important target for cancer therapy,” added Topian.
Source: 2012 Annual Meeting of the American Society for Clinical Oncology