Onyx Pharmaceuticals Inc. (ONXX), which has seen its shares double after the approval of the blood-cancer drug Kyprolis in July, is on the hunt for new drugs to add to its pipeline.

"We've got great prospects for this company, so there is every indication that we should just keep going on our own," Chief Executive N. Anthony Coles said in an interview after the firm's investor meeting in New York Thursday. "The way to build a successful, sustainable business is through acquisitions, either companies or products -- even licensing deals."

The strategy is intended to help Onyx transform itself from a drug development shop dependent on partners like Bayer AG (BAYRY) to shoulder sales costs to a full-fledged pharmaceutical company with its own sales organization and multiple revenue streams. Mr. Coles said he's interested in acquiring more biopharmaceutical drugs, which can be sold at premium prices, but are also more costly to develop and manufacture.

Analysts, meanwhile, are watching closely for whether the company, based in South San Francisco, Calif., can become more disciplined in its spending and begin to generate profits.

"Onyx is in transition from a royalty and development company to a revenue and commercial one," and some companies have suffered hiccups during the transition, said Geoff Porges, a Sanford C. Bernstein analyst, in a note to investors Friday.

Investor interest in the company is being driven by Kyprolis, which Onyx acquired through its 2009 acquisition of start-up Proteolix Inc.

On Thursday, Onyx said it would soon begin two late-stage trials to help get the drug approved in more patients, including newly diagnosed patients who haven't received treatment previously and are ineligible for stem-cell transplants. Kyprolis is currently only approved for relapsed cancer patients whose tumors don't respond to other treatments.

If Onyx can gain expanded approvals for the drug, as analysts expect, Kyprolis could have annual sales of $2 billion to $3 billion after 2018, according to Mr. Porges. Last week, the National Comprehensive Cancer Network, which creates treatment guidelines, recommended Kyprolis with new patients, which could help bolster off-label use of the drug ahead of formal approval.

However, Kyprolis is competing against several existing drugs for multiple myeloma, a blood cancer that kills 10,710 Americans annually. Its rivals include Velcade, made by Takeda Pharmaceutical Co. (4502.TO) and Celgene Corp.'s (CELG) Pomalyst, which received U.S. regulatory approval in February.

Dr. Coles, a trained cardiologist, said he hoped to make deals that would replicate the success of the Proteolix acquisition, for which Onyx agreed to pay $276 million upfront and up to $539 million in milestone payments.

He said he particularly is interested in drug candidates with biomarkers, a diagnostic tool that can predict which patients will respond to a certain therapy. The company also is looking at adding, among other areas, a class of biotechnology drugs known as monoclonal antibodies, which the Mayo Clinic says are designed to attach to the specific defects of cancer cells.

Onyx, which ended the fourth quarter with $492.8 million in cash and cash equivalents and raised $352 million in a stock sale in January, may beef up its pipeline without an outright acquisition of a company, an approach that could be less costly and carry fewer risks. "We could buy the product, not the company, or license rights in certain parts of the world," he said, adding that the company would potentially do all of those things.

Onyx shares recently traded at $87.75, down 1% on the day.

Another question surrounding Onyx is how soon it can become profitable. The firm is still spending large sums on clinical trials to gain new indications for Kyprolis and its liver and kidney cancer drug Nexavar. Bernstein's Mr. Porges predicts Onyx will break even next year, but not generate significant earnings before 2016.

Dr. Coles defended the firm's research and development spending, projected to be between $400 million and $450 million this year, as being directed toward advancing Kyprolis, its most promising product.

"We really want to make sure that we're investing appropriately and strategically in Kyprolis," he said. "We would hate to shortchange any opportunity to bring Kyprolis to patients."

Write to Joseph Walker at Joseph.Walker@dowjones.com

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