By Karen Pihl-Carey

Antigenics LLC went public Friday with an initial public offering of 3.5 million shares that raised $63 million in gross proceeds.

By the end of the day, those shares (NASDAQ:AGEN) were trading for more than triple the $18 offering price, to close at $61.375, up $43.375, or 241 percent.

The New York-based company originally intended to raise $46 million when it filed its initial registration statement with the SEC in late November (see BioWorld Today, Dec. 1, 1999, p. 1). In January, it amended its filing, showing it intended to raise $55.2 million from 3.45 million shares priced at a maximum of $16 apiece. Then last week, the company registered for an additional 575,000 shares and priced the offering at a higher rate of $18 per share.

Total proceeds, which the company expects will be about $58.59 million, not including an overallotment option, will go toward funding clinical trials of Antigenics' lead product, the cancer vaccine Oncophage, as well as preclinical and development activities and general corporate purposes, which could include an increase in administrative staff. The company may decide to use some of the funds to increase its manufacturing capacity or to acquire businesses or products.

The offering was led by Minneapolis-based U.S. Bancorp Piper Jaffray and co-managed by Fleetboston Robertson Stephens Inc., of New York. The underwriters have a 30-day option to purchase up to 525,000 additional shares to cover any overallotments. If exercised in full, the option would gross Antigenics another $9.45 million.

The company now has about 24.2 million shares outstanding. Options on another 2 million shares also are outstanding.

Antigenics, formed in March 1994, is focused on heat-shock protein-based immunotherapeutics, which modulate the immune system to fight disease. Oncophage is in six Phase II or Phase I/II trials in renal cell carcinoma, metastatic melanoma, colorectal cancer and gastric cancer. The company expects to begin soon Phase II trials of Oncophage to treat sarcoma and low-grade indolent non-Hodgkin's lymphoma, as well as a pivotal Phase III trial in renal cell carcinoma by mid-2000.

Oncophage consists of purified, patient-specific heat shock protein-peptide complexes. The therapy is manufactured when a patient's tumor is removed and shipped frozen overnight to Antigenics' manufacturing facility in Woburn, Mass. The company purifies Oncophage from the tumor tissue in less than 10 hours, then ships it frozen back to the patient, who is injected with it on an outpatient basis four to six weeks after surgery, and then once per week for four to six weeks.

The company also is conducting preclinical studies in infectious diseases and autoimmune disorders, and it expects to file an investigational new drug application with the FDA this year for a therapeutic for genital herpes.

For 1999, Antigenics had a net loss of $18.124 million. The company had cash and cash equivalents of about $46.4 million as of Dec. 31. It has not generated any revenues since its inception.