Plexxikon Inc. Advances Novel Targeted Treatment PLX3397 in Blood Cancer

News | 12. 12. 2011


Plexxikon Advances Novel Targeted Treatment PLX3397 in Blood Cancer

Berkeley, CA, December 12, 2011

Plexxikon Inc., a member of Daiichi Sankyo Group, today announced scientific findings from preclinical studies showing that treatment with a novel oral agent, PLX3397, selectively inhibited key cancer-driving Flt3 mutations that occur in 20-30 percent of acute myeloid leukemia (AML) patients. In a preclinical model of AML, PLX3397 showed significant tumor regression. This preclinical work also showed that PLX3397 retained activity against certain drug-resistant forms of mutated Flt3 that can occur with other treatments. These scientific findings were presented during the American Society of Hematology (ASH) Conference, taking place December 10-13, 2011 in San Diego (Abstracts #764 and #3632). Plexxikon recently initiated a Phase 1/2 study in AML patients, further described at

“Given PLX3397’s selectivity for relevant mutations, we are exploring this potential personalized medicine for AML patients with Flt3 mutations,” said K. Peter Hirth, Ph.D., chief executive officer of Plexxikon. “Plexxikon’s hallmark capability to design selective kinase inhibitors enables clinical researchers to test the hypotheses of such targeted therapies directly and rapidly.”

Phase 1 dose escalation testing in patients with solid tumors has been completed, and showed that PLX3397 reached therapeutic drug levels that were well tolerated at the doses tested. Two Phase 2 studies are now under way to further evaluate PLX3397, including one study in Hodgkin lymphoma and another study recently initiated in patients with Flt3-mutated AML. Plasma from Phase 1 patients contained sufficient levels of PLX3397 to block signaling in Flt3-mutant AML cells ex vivo. Additionally, PLX3397 has been tested in primary AML patient blood samples, which showed a clear dose response to drug at clinically achievable drug levels.

About PLX3397
PLX3397 is an oral agent that is being evaluated in several clinical trials for the treatment of different cancers, including AML. PLX3397 selectively co-inhibits three key targets, allowing down-modulation of a number of cell types, including macrophages, microglia, osteoclasts and mast cells, as well as the inhibition of Flt3 mutations that are key oncogenic drivers in AML.

About Plexxikon
Plexxikon, a member of 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 drug Zelboraf™ (vemurafenib/PLX4032) was approved by the FDA in August 2011, and is being co-promoted in the U.S. by Daiichi Sankyo Inc. and Genentech. The company is developing a portfolio of clinical and preclinical stage compounds to address significant unmet medical needs in oncology, as well as several other therapeutic indications. Plexxikon’s 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.