Sept. 23, 2009

San Francisco Business Times

Plexxikon: Melanoma drug shrinks tumors

An early-stage oral metastatic melanoma treatment from Plexxikon Inc. has reduced tumor size in 70 percent of patients, and the Berkeley company and partner Roche said larger trials will start shortly.

The announcement is the second major melanoma treatment news from a Bay Area-related company at the European Cancer Organisation/European Society for Medical Oncology conference in Berlin. Roche reported that the Genentech-developed drug Avastin with chemotherapy failed to show a significant improvement in progression-free survival in patients with malignant melanoma.

Fifteen of 31 patients involved in the Phase I extension study of Plexxikon’s PLX-4032 saw their tumors regress more than 50 percent, the company said. Tumors shrank more than 30 percent in 18 patients.

Patients in the trial have undergone at least one prior treatment and tested positive for BRAFV600E, a cancer-causing mutation that occurs in about half of melanomas and about 8 percent of all solid tumors.

Plexxikon also is helping to develop a diagnostic test for the mutation.

It is too early in the extension study to report median progression-free survival, the length of time during and after treatment in which a patient lives without the disease getting worse, Plexxikon said. But, the company added, an analysis of an earlier dose-escalation study indicates that progression-free survival is seven months as patients continue treatment.

“Since we have now confirmed the earlier Phase I results for PLX-4032 in metastatic melanoma, we are moving quickly to advance this product candidate to pivotal trials, which we expect to start shortly,” Plexxikon CEO Peter Hirth said in a press release.

More than 50,000 people in the United States and 160,000 worldwide are diagnosed with melanoma each year.

Plexxikon, which is codeveloping PLX-4032 with Roche under a 2006 license and collaboration deal, also said it will enroll a group of patients with colorectal cancer in another extension study by the end of the year.