Amgen will await three-year data before submitting the RANK ligand inhibitor denosumab for treatment of postmenopausal osteoporosis, the company said April 19.

"We believe three-year fracture data will provide the basis for regulatory approval, based on the novel mechanism of action of denosumab," Amgen Exec VP-Research & Development Richard Perlmutter said during the firm's first quarter earnings call. Data from the Phase III trial will not be available until late 2008.

Primary endpoints for the 1,100-patient trial include change in bone mineral density and fracture rates.

Amgen had previously suggested that it might be able to file for the postmenopausal osteoporosis indication using data from a two-year interim analysis of the trial.

However, "after discussions with FDA, we felt that the right thing to do would be to look at three-year data, which would give us the longest-term exposure and harmonize our U.S. and European submission. That's our current plan and that's what we're going forward with," Perlmutter said.

Since the postmenopausal osteoporosis filing will be based on three-year data, Perlmutter said the company will not conduct the interim analysis to avoid reducing the statistical power of the study. "With our decision that we're going to use three-year data to file, there's not much point in doing a two-year analysis," he added.

Amgen also said it wants the best chance of demonstrating a statistically significant reduction in hip fractures, which is more likely with longer-term data.

Additional Phase III studies of denosumab in preventing osteoporosis are ongoing, the firm said.

Denosumab is also being studied in separate Phase III trials for preventing bone marrow loss in breast cancer and prostate cancer patients undergoing ablative therapy. A Phase III trial of prevention of bone metastases in prostate cancer patients began in 2006, with three other studies planned for the second and third quarter to evaluate skeletal-related events in patients with metastatic bone disease.

Perlmutter suggested that there is a small chance that the firm could file for an oncology claim in advance of a postmenopausal osteoporosis claim.

"Is it possible we could have a data set come forward that we would think was so compelling that we would feel as if we needed to file in an oncology setting as an example before we filed in postmenopausal osteoporosis, certainly that's a possibility," he said.

On April 3, Amgen completed its acquisition of Abgenix, which eliminated future royalties that Amgen would have paid to Abgenix on denosumab and gave the firm full ownership of the pending oncologic panitumumab (¹ Also see "Amgen To Acquire Panitumumab Development Partner Abgenix" - Pink Sheet, 14 December, 2005.).

-Todd Leeuwenburgh

Amgen Denosumab Osteoporosis Submission To Await Three-Year Data

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