A biotechnology company developing a novel, personalized cancer treatment said Monday the vaccine showed promise in a small segment of patients with advanced skin cancer.

Antigenics Inc.'s (search) announcement was made before the stock markets opened and the New York-based company's share price rose 67 cents to close at $5.68 on the Nasdaq Stock Market.

Antigenics executives and Wall Street analysis warned that the announcement Monday was based only on preliminary results gleaned from between 60 and 80 patients involved in larger, advanced experiment involving 322 patients worldwide.

The company's vaccine Oncophage (search) didn't improve the life expectancy of the group when taken as a whole and the company said it will now concentrate its efforts on the segment that the drug showed promise in.

The results showed patients with cancer less widespread than the rest of the group who received the experimental vaccine Oncophage lived an average of about 21 months each, 50 percent longer than expected.

"It's encouraging," said Needham & Co. Inc. analyst Mark Monane. "But it's all very preliminary."

Monane estimates that about 1,400 new patients a year could benefit from Oncophage if the preliminary results hold up. Company executives said sales could reach $200 million annually.

But any regulatory approval is at least three years away, Monane said.

The beneficial results aren't "statistically significant" and are can't be used for marketing approval from the Food and Drug Administration. Instead the company will have to conduct another large-scale experiment focused exclusively on the patient population that the drug showed promised on.

"While these results aren't statistically significant, we believe that the improved survival benefit observed with Oncophage signals a meaningful clinical benefit," said Renu Gupta, who is in charge of the company's research.

Oncophage is a cancer vaccine that aims to trick patients' immune system to attack the disease, a concept researchers hope will yield treatments with fewer side effects than the toxic chemotherapy now used.

Oncophage is tailor-made from tissue collected from each patients cancerous tumors removed by cancer doctors.