Amgen (Nasdaq: AMGN) announced top-line results from a Phase 3 trial evaluating XGEVA(TM) (denosumab) versus placebo in 1,432 men with castrate-resistant prostate cancer. The trial, known as the '147 study, demonstrated that XGEVA significantly improved median bone metastasis-free survival by 4.2 months (HR=0.85, 95 percent CI 0.73-0.98, p=0.03) compared to placebo (primary endpoint), and significantly improved time to first occurrence of bone metastases (secondary endpoint). Overall survival was similar between the XGEVA and placebo groups (secondary endpoint).

Overall rates of adverse events and serious adverse events were generally similar between XGEVA and placebo, with hypocalcemia and osteonecrosis of the jaw (ONJ) observed at increased frequencies in the XGEVA arm. The yearly rate of ONJ in the XGEVA-treated group was similar to what has been observed in prior XGEVA trials.

"Our data demonstrate that XGEVA, which antagonizes the RANK Ligand axis, limits the ability of tumors to colonize bone, an important finding for men at risk for bone metastases and their healthcare providers," said Roger M. Perlmutter, M.D., Ph.D., executive vice president of Research and Development at Amgen. "We look forward to presenting these landmark data at an upcoming medical conference."

The RANK Ligand pathway, first discovered by Amgen scientists in the mid-1990s, is believed to play a central role in cancer-induced bone destruction, regardless of cancer type. Data suggest that in bone metastasis, the invasion of cancer is facilitated by bone destruction. Hence, increased bone resorption due to increased RANK Ligand expression appears to augment bone metastasis.

XGEVA is a fully human monoclonal antibody that binds to RANK Ligand, a protein essential for the formation, function and survival of osteoclasts (the cells that break down bone). XGEVA prevents RANK Ligand fromactivating its receptor, RANK, on the surface of osteoclasts, thereby decreasing bone destruction and halting release of growth factors, making the environment less conducive to tumor growth.

About Study '147

Study '147 was a randomized, placebo-controlled, multi-center Phase 3 study comparing the treatment effect of XGEVA with placebo on prolonging bone metastasis-free survival in men with hormone-refractory (castrate-resistant) prostate cancer with rapidly-rising PSA levels who had no bone metastases at baseline. The primary endpoint of the trial was time to first occurrence of bone metastasis or death from any cause, with secondary endpoints including time to first occurrence of bone metastasis (excluding death) and overall survival.

XGEVA Skeletal-Related Events Regulatory Status

XGEVA was approved by the U.S. Food and Drug Administration (FDA) for the prevention of skeletal-related events (SREs) in patients with bone metastases from solid tumors on Nov. 18, 2010. XGEVA is not indicated to prevent SREs in patients with multiple myeloma.

Administered as a single 120 mg subcutaneous injection every four weeks, XGEVA provides a new option for urologists and oncologists to prevent serious bone complications in men with prostate cancer.

Amgen has also submitted marketing applications for XGEVA in the European Union, Australia, Canada and Switzerland. In Japan, Amgen is working with its licensing partner, Daiichi-Sankyo Company, Limited and a marketing application was submitted.

XGEVA Important Safety Information

XGEVA can cause severe hypocalcemia. Correct pre-existing hypocalcemia prior to XGEVA treatment. Monitor calcium levels and administer calcium, magnesium, and vitamin D as necessary. Advise patients to contact a healthcare professional for symptoms of hypocalcemia.

Osteonecrosis of the jaw (ONJ) can occur in patients receiving XGEVA. Patients who are suspected of having or who develop ONJ while on XGEVA should receive care by a dentist or an oral surgeon. In these patients, extensive dental surgery to treat ONJ may exacerbate the condition.

The most common adverse reactions in patients receiving XGEVA were fatigue/asthenia, hypophosphatemia, and nausea. The most common serious adverse reaction in patients receiving XGEVA was dyspnea. The most common adverse reactions resulting in discontinuation of XGEVA were osteonecrosis and hypocalcemia.

Denosumab is also marketed as Prolia(TM) in other indications.

Bone Metastases: Prevalence and Impact

Bone metastases occur in more than 1.5 million patients with cancer worldwide and are most commonly associated with cancers of the prostate, lung, and breast, with incidence rates as high as 75 percent of patients with metastatic disease. (i)

The total economic burden of patients with bone metastases in the U.S. alone estimated to be $12.6 billion annually.

Denosumab and Amgen's Research in Bone Biology

The denosumab development program demonstrates Amgen's commitment to researching and delivering pioneering medicines to patients with unmet medical needs. Amgen is studying denosumab in numerous tumor types across the spectrum of cancer-related bone diseases. Over 11,000 patients have been enrolled in the denosumab oncology clinical trials. In addition to study 147, XGEVA is also being investigated for its potential to delay bone metastases in breast cancer.

(i) Coleman RE. Skeletal complications of malignancy. Cancer. 1997; 80(suppl): 1588-1594.

Source: Amgen

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