Buried in Amgen's third-quarter earnings release came bad news that the company received a second Complete Response letter from FDA regarding its BLA for Prolia (denosumab) for prevention of bone loss caused by hormone ablation therapy in breast and prostate cancer.

The Complete Response Letter on the HALT applications requested additional information on the safety of Prolia in patients with breast cancer receiving aromatase inhibitor therapy and patients with prostate cancer receiving androgen deprivation therapy, the Thousand Oaks, Calif. company revealed deep down in its Oct. 21 release.

"Results from additional adequate and well-controlled clinical trials demonstrating that Prolia has no detrimental effects on either time-to-disease progression or overall survival" will be needed, according to the letter.

It's unclear how long it will take to comply. The company said it is now reviewing the letter and plotting its next steps.

Amgen spokesperson Lisa Rooney said the Complete Response letter for the HALT applications came this week but declined to provide an exact date of receipt. The company had announced on Oct. 19 that it received a Complete Response letter for Prolia in the treatment and prevention of postmenopausal osteoporosis (Also see "Amgen Perfectly Positioned To Deal With Prolia Complete Response Letter; Quick Turn-Around Expected" - Pink Sheet, 19 October, 2009.).

The fact that FDA issued two response letters separately issued implies that the agency has split the company's Prolia BLA into two parts: PMO and the cancer indications.

For PMO, the agency has not asked for additional studies as yet and analysts are expecting an eight-month delay to the filing.

Analysts appeared unfazed by the news of a second Complete Response letter during an investors' call, which was held right after the markets closed Oct. 21.

A Complete Response letter for the cancer indications could have been expected considering the thumbs down for these indications at an August advisory committee (Also see "Amgen Perfectly Positioned To Deal With Prolia Complete Response Letter; Quick Turn-Around Expected" - Pink Sheet, 19 October, 2009.). The PMO letter, however, was a bit surprising given that members had voted in favor of approval.

Also as part of its earnings release, Amgen said it expects that data from a study of the effect of denosumab on skeletal-related events in patients with bone metastases from prostate cancer will be available in the first quarter of 2010. Results from this and other SRE studies could be used in support of the oncology indications, according to the company.

- Emily Hayes (e.hayes@elsevier.com)

Amgen Buries Second FDA Action Letter For Bone Drug in Cancer Indications

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