June 9, 2009

Proteolix Presents Clinical Data From Two Clinical Studies Of Carfilzomib In Multiple Myeloma At The 14th Congress

'Carfilzomib monotherapy achieves durable responses in relapsed multiple myeloma patients regardless of their prior exposure to bortezomib, and notably, a number of patients remain progression free after twelve cycles,' said Dr. Stewart. 'Further, carfilzomib has been generally well tolerated, and the compound's selectivity appears to avoid the off-target effects, such as peripheral neuropathy, associated with currently available proteasome inhibitors.'

Adverse events were generally mild and manageable and carfilzomib has been well tolerated for up to one year. Of 31 patients treated, 29 percent have received 12 full cycles of treatment.

These data were reported by Dr. Stewart in an oral presentation, titled '# 0474: Safety and Efficacy Update of PX-171-004, an Open-label Phase II Trial of Carfilzomib in Relapsed Multiple Myeloma,' on Saturday, June 6, 2009.

Carfilzomib Combination with Lenalidomide is Well-Tolerated; Achieves Responses in Heavily Pre-treated Patients at Low Doses

Positive preliminary data from an ongoing Phase 1b dose-escalating trial of carfilzomib in combination with lenalidomide and low-dose dexamethasone in relapsed and refractory patients was presented by Michael Wang, M.D., of the University of Texas MD Anderson Cancer Center on Sunday, June 7, 2009. The Phase 1b clinical trial is designed to evaluate safety and to establish a maximum-tolerated dose of carfilzomib in combination with lenalidomide and dexamethasone administered on a 28-day treatment cycle. Lenalidomide in combination with dexamethasone is currently indicated for use in patients with multiple myeloma who have had at least one prior therapy.

To date, the combination of carfilzomib and lenalidomide was well tolerated in heavily pre-treated patients and adverse events were manageable. The most common adverse events reported include anemia and fatigue. No cases of peripheral neuropathy, a common adverse event associated with approved proteasome inhibitors, have been reported. A maximum-tolerated dose has not yet been established and dose-escalation in this trial continues.

Sixty-one percent of the 18 patients evaluable for efficacy achieved very good partial, partial or minor responses. Responses occurred in the first 28-day cycle of treatment at doses well below the maximum-tolerated dose for either lenalidomide or carfilzomib alone. Initial responses improved with continued therapy. Potent inhibition of the proteasome has been observed and the lenalidomide/dexamethasone combination does not appear to interfere with carfilzomib's activity.

'Results observed to date in our Phase 1b combination study of carfilzomib are very promising,' said Michael Kauffman, M.D., Ph.D., Chief Medical Officer of Proteolix. 'We believe that carfilzomib in combination with lenalidomide and dexamethasone should provide superior activity to lenalidomide and dexamethasone alone. In addition, the lack of overlapping toxicities and absence of peripheral neuropathy may allow for long-term dosing - and ultimately, sustained clinical benefit.'

Dr. Wang presented interim data from the Phase 1b clinical trial during the Novel Therapeutics and Drug Resistance session in an oral talk, titled '#1070: PX-171-006: Phase IB Multicenter Dose Escalation Study of Carfilzomib (CFZ) plus Lenalidomide (LEN) and Low Dose Dexamethasone (LODEX) in Relapsed and Refractory Multiple Myeloma (MM) - Preliminary Results.'

About Multiple Myeloma

According to the American Cancer Society, in 2009, approximately 20,500 new cases of multiple myeloma will be diagnosed in the United States. Newly diagnosed patients have treatment options that include combination chemotherapeutic agents and stem cell transplantation. While many patients respond to treatment, most eventually relapse and require subsequent treatment. Few patients are ultimately cured of their disease. In spite of advances in the treatment of multiple myeloma, this year alone, approximately 10,500 patients are expected to die of the disease.

About Carfilzomib

Carfilzomib is the first in a new class of selective, irreversible proteasome inhibitors. Carfilzomib produces specific and sustained inhibition of the proteasome, leading to apoptosis in cancer cells with minimal off-target effects. In Phase 1 and Phase 2 clinical trials, carfilzomib has demonstrated single-agent activity in hematologic malignancies and solid tumors, including multiple myeloma, Waldenstrom's macroglobulinemia, mantle cell lymphoma and renal cell carcinoma.

Proteolix is conducting a comprehensive clinical development program evaluating carfilzomib for the treatment of multiple myeloma, including an ongoing accelerated approval study in heavily pre-treated relapsed/refractory patients and a Phase 2 clinical trial in relapsed patients stratified by prior treatment with bortezomib. Both Phase 2 clinical trials are being conducted by Proteolix in collaboration with the Multiple Myeloma Research Consortium (MMRC). A Phase Ib clinical trial of carfilzomib in combination with lenalidomide and dexamethasone in patients with relapsed multiple myeloma is also ongoing. In addition, Proteolix is conducting a single-agent Phase 2 clinical trial of carfilzomib in patients with recurrent or advanced solid tumors.

About Proteolix

Founded in December 2003, Proteolix, Inc. is a privately-held biotechnology company, headquartered in South San Francisco, dedicated to discovering, developing and commercializing novel therapeutics that target protein degradation pathways for cancer and autoimmune diseases. Proteolix's lead product, carfilzomib, is the first in a new class of selective, irreversible proteasome inhibitors. Proteolix is also developing a pipeline of novel proteasome inhibitors, including a selective, oral proteasome inhibitor and a selective immunoproteasome inhibitor.

Source: Proteolix, Inc