Onyx Pharmaceuticals, Inc. (ONXX) recently presented positive top-line results on its multiple myeloma candidate, carfilzomib. Results from the phase IIb study showed that patients treated with carfilzomib achieved an overall response rate of 24%. While the median duration of response was 7.4 months, the clinical benefit rate was 36%.

Onyx Pharma said that carfilzomib was well-tolerated with no unexpected or new toxicities being observed. Onyx Pharma will present full data from the study at an upcoming scientific meeting.

The open-label, single-arm study (003-A1) was conducted in patients who had undergone prior therapy (a median of five prior lines of treatment) and whose disease had relapsed and was not responding to the last line of treatment.

Onyx to Seek Accelerated Approval by Year-End

Onyx Pharma intends to discuss the phase IIb data with the US Food and Drug Administration (FDA) and determine the steps required for the filing of a new drug application (NDA). Onyx Pharma is looking to file its NDA by year-end and hopes to gain accelerated approval for carfilzomib.

Onyx Pharma is currently conducting a randomized international phase III trial (ASPIRE) which will evaluate the combination of Celgene’s (CELG) Revlimid (lenalidomide) and low dose dexamethasone with or without carfilzomib in relapsed multiple myeloma patients. The study is being conducted under the FDA’s special protocol assessment (SPA) program.

Another phase III study (FOCUS) will be conducted to evaluate the candidate in patients with advanced myeloma. The company will use results from this study to support its European marketing approval application.

The multiple myeloma market represents huge commercial potential. Multiple myeloma is the second most common hematologic cancer – it is estimated that about 50,000 people in the US are living with the disease with 20,000 new cases being diagnosed every year. Carfilzomib could hit the market as early as late 2011 if the FDA grants accelerated approval.

Underperform on Onyx

Although we are encouraged by the positive results on carfilzomib, we currently have an Underperform recommendation on Onyx Pharma based on its disappointing performance in the first quarter of 2010. Despite an increase in revenues, Onyx Pharma slipped to a loss during the first quarter driven by increased operating expenses.

Moreover, although revenues recorded growth based on strong sales of Nexavar, we remain concerned about increased competition in the kidney cancer market. Besides, the company lowered its 2010 Nexavar sales guidance based on various factors. We believe that unfavorable foreign exchange (Fx) movement, increased competition, reimbursement issues in certain countries and lower sales growth in Japan will continue to affect Nexavar’s performance.
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