CHICAGO ( TheStreet) -- Patients with advanced melanoma, a deadly form of skin cancer, are living longer following treatment with two new drugs developed separately by Roche ( RHHBY) and Bristol-Myers Squibb ( BMY), researchers reported Sunday at the American Society of Clinical Oncology annual meeting.

While neither drug provides melanoma patients with a cure, the results from phase III studies of Roche's vemurafenib and Bristol's Yervoy are being heralded at this year's ASCO meeting as a triumph of science over a deadly cancer that has long alluded the best efforts of researchers.

"The studies presented today highlight tremendous advances in the treatment of metastatic melanoma, said Dr. Lynn Schuchter, a University of Pennsylvania cancer expert. "Until recently, we've had limited options for our patients, and little hope for long-term survival. In the past two years, we've seen remarkable progress with immunotherapy, and now, a promising targeted therapy."

Bristol's Yervoy was approved earlier this year and Roche's vemurafenib is still under regulatory review, but both drugs could generate $1 billion or more in sales, analysts say.

Roche's vemurafenib is noteworthy in that it is the first drug developed specifically to target and block a mutation known as V600E in the BRAF gene. This mutation is found in approximately half of all melanoma tumors.

The phase III study compared the efficacy of vemurafenib to the chemotherapy drug dacarbazine in 675 patients with previously untreated advanced, metastatic melanoma. All patients in the study had the defective mutation in the BRAF gene.

At a planned interim analysis, vemurafenib-treated patients had a 63% reduction in risk of death compared to those receiving dacarbazine. Patients who received vemurafenib also had a 74% reduction in the risk of tumor progression or death compared to dacarbazine. All results were statistically significant in favor of vemurafenib.

Extending survival is the gold standard for cancer drug clinical trials but in this study, vemurafenib also shrank more tumors than dacarbazine -- with response rates of 48.4% compared to 5.5%.

"This is really a huge step toward personalized care in melanoma," said Dr. Paul Chapman, a melanoma expert at Memorial Sloan-Kettering Cancer Center in New York and the lead investigator in the vemurafenib study.

Due to the early and overwhelmingly positive results, the vemurafenib study was stopped early and patients in the dacarbazine arm were allowed to cross over and receive the Roche drug.

Fewer than 10 percent of patients who received vemurafenib experienced problems with high levels of toxicity, grade three or worse. The most common side effects were skin rashes, photosensitivity, and joint pain. About 12% patients developed a low-grade skin cancer, squamous cell carcinoma, but once removed, patients could continue treatment with vemurafenib.

Bristol's Yervoy belongs to a new class of drugs that harness a patient's own immune system to target and fight cancer. Yervoy is an antibody that targets cytotoxic T-lymphocyte associated antigen (CTLA-4), which acts like a brake on the T-cell, a key component of the immune system. Yervoy removes this brake, enabling a patient's own T cells to attack the cancer.

Yervoy was approved in March to treat patients with advanced metastatic melanoma that was no longer responding to previous treatments. The study being highlighted at ASCO this year demonstrates Yervoy's ability to prolong survival in previously untreated melanoma patients.

In this study, 502 patients with metastatic melanoma were randomized to treatment with Yervoy plus the chemotherhapy drug dacarbazine or placebo and dacarbazine. The Yervoy-chemotherapy treatment resulted in a 28% reduction in the risk of death compared to the chemotherapy alone treatment.

The overall survival rate for the Yervoy combination after one year was 47.3% compared to 36.3% for dacarbazine alone. After two years, the overall survival rate was 28.5% for the Yervoy combination versus 17.9 percent for dacarbazine alone. At three years, overall survival was 20.8% for the combination compared to 12.2% for chemotherapy alone.

"This trial's three-year endpoint is significant. No randomized trial for metastatic melanoma has followed patients for this long, and it demonstrates the durability of this survival benefit, now out to three years in this population, and even four years in some cases," said Dr. Jedd Wolchok of Memorial Sloan-Kettering Cancer Center in New York.

Wolchok added, "It's one of the advantages of immunotherapy. The immune system is a 'living drug,' able to adapt itself to changes in the tumor that might otherwise lead to resistance when treated with chemotherapy or a pathway inhibitor."

Cancer immunotherapy drugs take longer to benefit patients and may not result in the rapid tumor shrinkage often seen with chemotherapy or targeted therapies even though they can prolong survival, experts say. This was evident in the Yervoy study, where patients treated with the drug reported a median time to tumor progression of 2.8 months compared to 2.6 months for the chemotherapy arm. The rate of tumor shrinkage attributed to Yervoy-dacabazine was 15% compared to 10% for dacarbazine alone.

--Written by Adam Feuerstein in Boston.

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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; click here to send him an email.

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