By Mary Welch

LeukoSite Inc., which develops drugs that block the disease-promoting actions of white blood cells, closed a nearly $12 million private placement of common stock to support a pivotal Phase II trial of Campath, a monoclonal antibody, for chronic lymphocytic leukemia (CLL) and additional research and development projects.

Current shareholders participated in the $11.8 million placement, as did two new investors: Goldman Sachs, of New York, and Perseus Capital LLC, of Washington. The Cambridge, Mass., company self-managed the transaction. The 1.97 million shares sold were priced at $6 per share.

LeukoSite's stock (NASDAQ:LKST) closed Monday at $7.375, unchanged.

Campath (LDP-03) has an intriguing history. Originally developed by Burroughs Wellcome plc (now Glaxo Wellcome plc, of London), the drug was tested for rheumatoid arthritis, non-Hodgkin's lymphoma and solid organ and bone marrow transplantations. It proved to be an inadequate treatment for non-Hodgkin's lymphoma and its degree of lymphocyte depletion was too high for a rheumatoid arthritis indication. (See BioWorld Today, May 15, 1997, p. 1.)

Glaxo Wellcome wasn't interested in the drug even though it had promising results with leukemia patients.

LeukoSite acquired the product and formed a partnership with Ilex Oncology Inc., of San Antonio, to develop Campath for CLL, which is the most prevalent form of adult leukemia in Western countries, affecting 120,000 in the U.S. and Europe.

A malignant disorder, the disease is characterized by accumulation of abnormal lymphocytes in the body. Over time, these cells spread, causing bone-marrow dysfunction and enlargement of the lymph nodes, liver and spleen.

Campath is designed to target the cell surface antigen DC52, which is found exclusively on lymphocytes, destroy the malignant cells and spare blood-forming (hematopoietic) stem cells necessary for a functioning immune system.

Campath BLA Expected In '99

When working properly, leukocytes, which include lymphocytes, rid the body of infectious organisms and repair damage to tissues and organs; when malfunctioning, leukocytes are linked to diseases such as lymphomas, leukemias, asthma, rheumatoid arthritis and HIV.

"Right now [Campath] is in a pivotal clinical study," said Gus Lawlor, vice president of corporate development and the chief financial officer of LeukoSite. "We expect to enroll 75 patients in multicenters in the U.S. and Europe and conclude the trial by the end of 1998. Results are expected in the first quarter of 1999."

Currently patients with CLL are treated with chemotherapy and, if that fails, with Fludarabine, a drug marketed by Schering AG, of Berlin. After that, there is no therapy.

"Eventually, the disease is fatal," said Lawlor. "Campath will give physicians a treatment option that has demonstrated clinical benefit."

Earlier investigational studies showed patients experienced a partial or complete remission with Campath.

LeukoSite intends to file a biologics license application (BLA) with the FDA next year. The drug could reach the market by 2000.

Analysts have estimated Campath's potential sales at between $75 million and $100 million within three years.

"We don't want to estimate future sales, but that's what we're hearing other people say," Lawlor said.

The new capital infusion also will be used to advance two other humanized monoclonal antibodies, LDP-O2 and LDP-O1.

LDP-O2, an antibody to the alpha4-beta7 integrin molecule, is being targeted for the treatment of inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis. The drug, being developed in conjunction with Genentech Inc., of South San Francisco, completed its Phase I trial and should start Phase II soon.

LDP-O1, for treatment of stroke and prevention of kidney transplant rejection, is in Phase I/IIa trials. LDP-01, an anti-integrin monoclonal antibody targeting CD18, should finish its trials by 1998.

"In addition, we have a range of small molecule programs under way for the treatment of various autoimmune and inflammatory diseases," Lawlor said. *