Plexxikon Announces Combination Trials for Vemurafenib in Melanoma

  • New Phase 2 Trial Initiated to Study Vemurafenib as Single Agent in Thyroid Cancer

Berkeley, CA—June 2, 2011 – Plexxikon Inc., a member of the Daiichi Sankyo Group, today announced new clinical trials in metastatic melanoma testing vemurafenib (PLX4032/RG7204) in combination with other state-of-the-art treatments, including an immunologic therapy and an investigational MEK inhibitor. Additionally, a new trial will test vemurafenib as a single agent in thyroid cancer patients who have the BRAF mutation. Vemurafenib targets the mutant BRAF protein, which is present in about half of melanomas, about 40-70 percent of thyroid cancer and about eight percent of all solid tumors.”

Vemurafenib has demonstrated consistent and positive results to-date as a single agent, and represents a potential new, important treatment option for melanoma patients. By combining vemurafenib with other scientifically rational agents, we hope to further enhance patient treatment outcomes,” said K. Peter Hirth, Ph.D., chief executive officer of Plexxikon. “We are equally excited about exploring vemurafenib treatment in other BRAF-mutant tumor types, particularly thyroid cancer, given the compelling signal for this cancer seen in our Phase 1 dose-escalation trial.”

About Combination Studies with Vemurafenib for Metastatic Melanoma
Earlier this year, a trial evaluating vemurafenib treatment with another investigational candidate, an oral agent targeting MEK kinase inhibitor, GDC-0973, was initiated in metastatic melanoma patients with the BRAF mutation. The addition of GDC-0973 to vemurafenib treatment in this study will enable evaluation as to whether the inhibition of two key parts of the BRAF/MEK cancer cell signaling pathway can improve treatment outcomes for patients, including potentially extending response duration. This trial is expected to enroll approximately 50 patients, with the goal of establishing safety, tolerability and activity of the two drugs given in combination.

Another trial testing vemurafenib treatment with an immunologic antibody infusion therapy for metastatic melanoma is also planned.

About Thyroid Cancer Trial with Vemurafenib
Also recently, a Phase 2 trial has been initiated to evaluate vemurafenib in refractory papillary thyroid cancer. In this trial, approximately 40 thyroid cancer patients with the BRAF mutation will receive vemurafenib at 960 mg BID. The primary endpoint for this study is best overall response rate. In the previous Phase 1 dose escalation trial, three thyroid patients were enrolled and treated at various lower dose levels. All three patients demonstrated activity of the drug as assessed by tumor shrinkage and prolonged stable disease. 

About Vemurafenib (PLX4032)
Vemurafenib is a novel, oral small molecule being developed for the treatment of melanoma and other cancers harboring the oncogenic BRAF mutation. Plexxikon utilized its structure-guided chemistry platform to discover vemurafenib, and initiated clinical development in 2006. Plexxikon and Roche signed a license and collaboration agreement in 2006 to co-develop vemurafenib. A DNA-based companion diagnostic to identify patients whose tumors carry the BRAF mutation also is being co-developed by Roche and Plexxikon in parallel with the therapeutic development of vemurafenib.

Current studies of vemurafenib are being conducted by Roche, Plexxikon and Genentech, a member of the Roche Group. Plexxikon recently announced the submission of applications for market approval for vemurafenib in the U.S. and Europe. During the marketing application review period, vemurafenib is available to eligible patients with BRAFV600 mutation-positive melanoma through a global patient access program. More information about this program or other vemurafenib studies is available at (in the U.S.) or or on the Roche Clinical Trials Registry at (in the EU). Genentech can also be contacted by calling the company’s clinical trial call center at 888-662-6728 or emailing

About Plexxikon
“Plexxikon, a member of the Daiichi Sankyo Group, is a leader in the structure-guided discovery and development of novel small molecule pharmaceuticals to treat human disease. The company’s lead compound, vemurafenib (PLX4032), is in late-stage clinical trials for the treatment of melanoma, and the subject of recent applications for marketing approval in the U.S. and Europe. PLX3397, the company’s next oncology candidate, has advanced to Phase 2 testing. The company is developing a portfolio of clinical and preclinical stage compounds to address significant unmet medical needs in oncology, as well as in several other therapeutic indications. Plexxikon’s proprietary Scaffold-Based Drug Discovery™ platform integrates multiple state-of-the-art technologies, including structural screening as a key component that provides a significant competitive advantage over other drug discovery approaches. 


Back to Press Releases