) -- An experimental drug from


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Array Biopharma

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shrank tumors in half of patients with melanoma of the eye and delayed the re-growth of tumors for twice as long as patients treated with temozolomide, a commonly used melanoma drug.

The phase II study of selumetinib, presented at the American Society of Clinical Oncology (ASCO) annual meeting, is the first to ever demonstrate a meaningful clinical benefit for patients with advanced melanoma of the eye.

Selumetinib is a pill which blocks a protein known as MEK used by cancer cells to grow. Array discovered selumetinib and licensed the drug to AstraZeneca in 2003. AstraZeneca is conducting phase II studies of selumetinib in non-small cell lung cancer, pancreatic cancer and thyroid cancer.

Melanoma of the eye is a rare cancer, with about 2,000 cases diagnosed in the U.S. each year. About half of patients develop metastatic disease with survival ranging from nine to 12 months. No currently approved drugs are effective in treating melanoma of the eye, including drugs for skin melanoma.

In the study, 98 patients with metastatic melanoma of the eye were randomized to treatment with selumetinib or temozolomide. Fifteen percent of selumetinib-treated patients achieving major tumor shrinkage while temozolomide produced no tumor shrinkage.

Selumetinib delayed the regrowth of tumors (progression-free survival) by a median of 15.9 weeks compared to 7 weeks for temozolomide.

Median overall survival for selumetinib-treated patients was 10.8 months compared to 9.4 months for temozolomide. The relatively small survival benefit was impacted by temozolomide patients who "crossed over" to receive selumetinib once their tumors started to grow again.

Selumetinib failed to demonstrate significant efficacy in the more widely diagnosed skin melanoma. In a phase II study also being presented at the ASCO meeting, the combination of selumetinib and dacarbazine reduced the risk of death by only 7 percent compared to dacarbazine plus a placebo. The narrow survival edge was not statistically significant.

Earlier this week, a


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MEK inhibitor known as Mekinist was approved by the FDA for patients with metastatic melanoma with two gene mutations known as BRAF V600E or V600K. Mekinist's approval was based on a pivotal study in which the drug delayed tumor growth by 3.3 months compared to chemotherapy.

AstraZeneca is conducting multiple phase II studies of selumetinib in other forms of cancer.

-- Reported by Adam Feuerstein in Chicago.

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Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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