Bloom Off the Denosumab Rose, but All Eyes on Oncology

(MoneyWatch)  Amgen's denosumab, which analysts have called the knight in shining armor set to save the big biotech's flagging blood product franchise, lost a bit of its luster last week.
An FDA advisory panel reviewed the drug for two types of bone loss: that associated with osteoporosis in postmenopausal women, and that induced by hormone ablation therapy in prostate or breast cancer.
The panel gave denosumab a thumbs up for treatment of osteoporosis and prostate cancer-associated bone loss, but a thumbs down for the treatment of breast cancer-associated bone loss and for prevention in all three indications.

Osteoporosis, at more than a billion dollars, is the biggest market and a big potential win for Amgen. But the mixed review and emphasis on safety issues (tumors, endocarditis, fractures) were undeniably bad news -- especially for a drug that has been hailed as Amgen's most important prospect.

As BNET reported previously, The Street has called denosumab "the most important new drug to come out of Amgen's research labs in years" and "a key to the company's future growth." Credit Suisse analyst Michael Aberman called it "critical to our thesis of Amgen returning to growth."

The FDA's decision is expected Oct. 19, and the agency tends to follow the recommendations of its advisory committees ?€" although it's certainly not obligated to.

Problem No. 1, according to a BioWorld article, is that even though most analysts expect approval in osteoporosis, it's not clear what the label will look like:

A worst-case scenario, a black-box warning similar to the label for Eli Lilly and Co.'s parathyroid hormone drug Forteo (teriparatide), would not come as a surprise to Leerink Swann analyst Joshua Schimmer. "We did not walk away from the discussion feeling warm and fuzzy regarding Dmab's PMO commercial prospects," he wrote in a research note.

Problem No. 2, BioWorld wrote, is denosumab's future in oncology ?€" the biggest market of them all. The drug has performed well thus far, matching Novartis AG's Zometa (zoledronic acid) in a Phase III multiple myeloma/solid tumor trial and beating it in a Phase III breast cancer trial. Data from two Phase III prostate cancer trials are expected next year -- but the advisory committee's safety concerns mean the drug's future is far less certain.