EMERYVILLE, Calif. ( TheStreet) -- Onyx Pharmaceuticals ( ONXX) is delaying an expected approval filing of its multiple myeloma drug carfilzomib in order to provide regulators with more information about the drug's manufacturing process, the company said Thursday.

Carfilzomib will be filed with the U.S. Food and Drug Administration by the middle of 2011, pushed back from Onyx's earlier estimate of an end-of-2010 filing.

Onyx said the carfillzomib delay came about after FDA raised questions and asked for more information about the company's plans to expand the production of the drug to meet commercial specifications. The clinical profile of carfilzomib has not changed, and no new safety signals have been observed, Onyx said.

"This is a timing issue," said Onyx CEO Tony Coles on a conference call.

Coles added that Onyx still plans to seek carfilzomib's approval under the FDA's accelerated approval regulations, typically reserved for cancer drugs that can show a meaningful benefit for patients who have no other treatment options.

In July, Onyx reported results from a pivotal phase IIb study demonstrating that carfilzomib was able to induce a clinically meaningful tumor response in 24% of multiple myeloma patients with a median duration of response of 7.4 months, according to study results that were independently verified and released by Onyx.

--Written by Adam Feuerstein in Boston.

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