May 02, 2016 9:09 AM ET


Company Overview of Plexxikon Inc.

Company Overview

Plexxikon Inc. develops small molecule pharmaceuticals. The company develops a portfolio of preclinical and clinical stage compounds to address unmet medical needs in oncology, CNS, autoimmune and bone, and other therapeutic areas. Its pipeline comprises Zelboraf (vemurafenib), an oral and small molecule that targets the BRAF mutation, occurring in about half of all cases of melanomas; and oral and investigational agent that co-inhibits kinase targets, FMS, and Kit and oncogenic Flt3 to treat diseases. The company’s pipeline also includes agents to treat neurological diseases, including pain, multiple sclerosis, and Alzheimer's disease; agents that target to address unmet medical needs in rh...

91 Bolivar Drive

Berkeley, CA 94710

United States

Founded in 2000





Key Executives for Plexxikon Inc.

Chief Executive Officer
Co-founder, Chairman of the Board and Member of Scientific Advisory Board
Age: 70
Co-Founder and Chairman of Scientific Advisory Board
Chief Financial Officer and Vice President
Compensation as of Fiscal Year 2015.

Plexxikon Inc. Key Developments

Plexxikon Inc. and Merck to Collaborate on Combination Study Evaluating Investigational Immuno-oncology Regimen

Plexxikon Inc. and Merck announced a collaborative clinical trial that will evaluate the combination of PLX3397, Plexxikon’s investigational CSF-1R inhibitor, and KEYTRUDA® (pembrolizumab), Merck’s anti-PD-1 therapy, which provides the potential for a double blockade of cancer-induced immune suppression. The Phase 1/2 trial will enroll patients with advanced melanoma and multiple other solid tumors with the goal of determining the safety and tolerability of the combination therapy. The trial is expected to begin enrollment by mid-year. PLX3397 is a novel oral small molecule that potently and selectively inhibits CSF-1R, KIT, and mutant FLT3 kinases. CSF1R and KIT regulate key components of both the tumor and its microenvironment (macrophages, osteoclasts, mast cells). In addition to melanoma and other solid tumors to be studied in this collaborative trial, PLX3397 is being evaluated in several other clinical indications, including tenosynovial giant cell tumor (TGCT), historically called pigmented villonodular synovitis (PVNS) or giant cell tumor of the tendon sheath (GCT-TS), breast cancer and glioblastoma. KEYTRUDA (pembrolizumab) is a humanized monoclonal antibody that blocks the interaction between PD-1 (programmed death receptor-1) and its ligands, PD-L1 and PD-L2. By binding to the PD-1 receptor and blocking the interaction with the receptor ligands, KEYTRUDA releases the PD-1 pathway-mediated inhibition of the immune response, including the anti-tumor immune response. KEYTRUDA is indicated in the United States at a dose of 2 mg/kg administered as an intravenous infusion over 30 minutes every three weeks for the treatment of patients with unresectable or metastatic melanoma and disease progression following ipilimumab and, if BRAF V600 mutation positive, a BRAF inhibitor. This indication is approved under accelerated approval based on tumor response rate and durability of response. An improvement in survival or disease-related symptoms has not yet been established. Continued approval for this indication may be contingent upon verification and description of clinical benefit in the confirmatory trials.

Oncosec Medical Incorporated and Plexxikon Inc. Collaborate to Explore Combination Immunotherapy in Preclinical Tumor Studies

OncoSec Medical Inc. announced a preclinical collaboration with Plexxikon Inc., to test the combination of Plexxikon's selective CSF-1R inhibitor with OncoSec's Immunopulse pIL-12. Intratumoral macrophages and other related cell types, like myeloid-derived suppressor cells, can be strongly immunosuppressive and block anti-tumor immunity. Given understanding of IL-12 as a potent driver of immunogenicity and tumor-infiltrating lymphocytes (TILs) and the potential role of tumor-resident myeloid cells in suppressing the anti-tumor effects of TILs, hypothesize that blocking CSF-1R with Plexxikon's selective CSF-1R inhibitor will lead to synergistic effects in the syngeneic B16.F10 melanoma mouse model. Interleukin-12 (IL-12) is an inflammatory cytokine that is believed to be a master regulator of the immune system, and is important in the up-regulation of both the innate and adaptive immune responses. IL-12 is a key driver of the cascade of biological events which ultimately lead to T-cell-specific killing of cancer cells. Moreover, cytokines and chemokines induced by this pathway also increase the recruitment of inflammatory T-cells into tumors.

Plexxikon, Inc. Announces Promising, Proof-Of-Concept Phase 1 Extension Clinical Data with PLX3397 in Pigmented Villonodular Synovitis

Plexxikon, Inc. announced promising, proof-of-concept Phase 1 extension clinical data with PLX3397 in pigmented villonodular synovitis (PVNS), a type of rare, often locally aggressive, musculoskeletal neoplasm that arises from the soft tissues of joints and tendons. Interim data from this ongoing trial show that all evaluable patients treated with PLX3397 achieved either partial responses or stable disease. PLX3397 is a novel, oral small molecule that potently and selectively inhibits CSF1R, KIT and oncogenic FLT3 kinases, which play important roles in cancer. CSF1R, in particular, has been shown to be a primary driver in PVNS. These data are being released as part of the American Society of Clinical Oncology (ASCO) 50(th) Annual Meeting Press Program. More detailed data will be presented at the ASCO 50(th) Annual Meeting, being held May 31-June 3 in Chicago. The data come from an extension cohort of a multicenter Phase 1 clinical study in solid tumors that enrolled 23 advanced PVNS patients who received at least one dose at the time of the interim analysis. Of the 14 patients with evaluable MRI scans, 11 patients (79 percent) achieved partial response and three patients (21 percent) had stable disease as assessed by a novel scoring method to measure PVNS tumor volume. Mean tumor size reduction was 61 percent. For the 23 enrolled patients, the most common treatment-related side effects were hair color changes, fatigue, nausea, swelling around the eyes, abnormal taste, diarrhea, vomiting, and decreased appetite. Treatment-related, severe adverse events were liver enzyme elevations, hyponatremia, anemia, fatigue, diarrhea, and neutropenia. PVNS tumors are known to express high levels of CSF1, which causes proliferation of tumor-associated macrophages, osteoclasts and other CSF1R-dependent cells. By selectively inhibiting CSF1R, PLX3397 should reverse the accumulation of macrophages and reduce PVNS tumor size. PLX3397 previously has been shown to inhibit CSF1R-dependent CD14+/CD16+ pro-inflammatory monocyte cell numbers in cancer patients.

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