A closer look at Dendreon's new prostate cancer treatment

Two weeks ago, Dendreon Corp. (DNDN) reported that its experimental prostate cancer treatment, the therapeutic vaccine Provenge, was significantly successful in prolonging patient survival, but said it would give more details at a later date at the American Urological Association (AUA) Annual Meeting. It didn't matter, shares of the biotech consequently soared some 130 percent as investors and patients alike hoped the results may clear the way for the long-awaited regulatory approval for the drug.

Today, Dendreon finally released the promised details, claiming they prove its unique prostate cancer treatment, Provenge, extended median survival in a large clinical trial by 4.1 months and increased three-year survival by 38 percent compared to a placebo (31.7 percent versus 23.0 percent).

What does this mean? First, a quick recap on Provenge, which unlike standard chemotherapy it is an active immunotherapy drug that aims to train the patient's own immune system to attack the cancer. Provenge is produced from a patient's white blood cells and tumor proteins, administered when the disease no longer responds to hormone blockers (the standard treatment). Patients treated with Provenge suffered from chills, fever, and headache, which Dendreon says were low grade with a short duration of 1-2 days following infusion. While Provenge is called a therapeutic vaccine, it does not prevent the disease, but treats it once the patient is already ill. Provenge is now the first of its kind to prolong survival in cancer patients.

The IMPACT study enrolled 512 men with advanced prostate cancer who no longer responded to hormone therapy with the primary endpoint was to determine whether treatment with Provenge prolonged overall survival of patients compared to a placebo.

The results mean that not only did Provenge increased survival of patients with advanced prostate cancer (25.8 months versus 21.7 months for Placebo), it also more than doubled the three-year survival rate seen in patients on Sanofi-Aventis' (SNY) Taxotere. Provenge reduced the risk of death by 22.5 percent compared to placebo, with a statistically significant value to rule out chance. It surpassed the 22 percent goal required to meet FDA approval. Provenge has failed to obtain FDA approval in 2007.

Different doctors presented with the study said the results confirm Provenge's clinical value to prolong survival in patients with advanced prostate cancer with a favorable benefit to risk profile. Still, others, like Dr. Otis Brawley, the American Cancer Society's chief medical officer sounded more cautious, even as he said he would vote for approval.

Dendreon plans to give the test results to the Food and Drug Administration by the end of this year in hopes of winning agency approval in 2010. Provenge has blockbuster potential if it is approved for marketing, with some analysts estimating that sales may reach $1 billion a year, providing both top line and bottom line growth for Dendreon in the coming years.

As I write this, Dendreon still hasn't resumed trading (shares were halted ahead of the release) and the last trade at 1:27 was some 45 percent down.
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