As it prepares to commercialize its hematopoietic stem cell purification technology, Cellerant Therapeutics Inc. raised $16 million in a Series B financing.

It may be the last time the Palo Alto, Calif.-based company has to turn to private investors. Cellerant expects to introduce its technology to the market within the next two years.

"The financing is very significant, both for us and, I think, for the industry, because it's been historically difficult to raise money for stem cell-based businesses," said Bruce Cohen, president and CEO of Cellerant. "This money will allow us to get to commercial revenue."

Cohen said the money should last the company one to two years. Cellerant last raised $10 million in a Series A financing, bringing the total money raised by the company to $26 million since its 2002 inception. (See BioWorld Today, May 30, 2003.)

Cellerant focuses on its hematopoietic stem cell (HSC) purification technology, which allows for the clinical use of adult-derived stem cells for indications in which conventional drug therapy has failed. Proceeds will help accelerate the commercial development of the HSC purification platform, and help initiate clinical trials of Cellerant's first cell-based product, human myeloid progenitors for radiation- and chemotherapy-induced neutropenia.

The HSC purification platform enables scientists to select pure stem cells from mobilized blood or bone marrow.

"We have a proprietary method for selecting stem cells and only stem cells," Cohen told BioWorld Today. "We pull the stem cells out and we leave behind all of the contaminants that we don't want. The stem cells have different surface markers than the other cells."

HSCs help cancer patients recover from the intensive treatment of high-dose chemotherapy and radiation. The cells are harvested from the patient before therapy and then infused back into the patient later to regenerate the blood-forming system, boosting the patient's ability to fight off disease and recover from injury.

The strategy has hit some roadblocks, however. The infusion of cells brings with it cancer cells that contaminate the rescue dose of stem cells. Cellerant's technology reduces the number of cancer cells to below detectable levels, eliminating the risk of bringing cancer back into a patient following effective chemotherapy.

"If you give somebody high-dose chemotherapy," Cohen said, "and you need to rescue them with their own blood-forming stem cells, when you give them back their own stem cells, our method allows you to do that in a way where you do not re-transfuse the cancer cells."

Likewise, the cell purification platform also eliminates T-cell contamination to below detectable levels, providing a greater opportunity for HSCs to be used in genetic blood disorders and autoimmune disease. Clinical data have shown that HSCs from a donor who does not carry the genetic predisposition to certain diseases can cure sickle cell disease, as well as lupus, Crohn's disease, rheumatoid arthritis, multiple sclerosis and Type I diabetes. The procedures, however, have been limited by the risk of a fatal complication, graft-vs.-host disease, caused by contaminating T cells.

"The stem cells will cure the disease if you can eliminate the risk of graft-vs.-host that would come from contaminating T cells," Cohen said. "The same method that we use to eliminate cancer cells eliminates T cells in that setting."

While Cellerant intends to begin confirmatory clinical trials of its platform technology in oncology, sickle cell disease and lupus by the end of this year, it also plans to start clinical trials in 2006 of its human myeloid progenitors, a manufactured cell product derived from adult HSCs that has been shown in animal models to be protective against neutropenia. One application is in cancer patients undergoing radiation and chemotherapy who often suffer from neutropenia, or a shortage of platelets and infection-fighting macrophages and neutrophils.

"It's also being developed as a counter-terrorism measure for people who are exposed to lethal doses of radiation," Cohen said.

Cellerant's portfolio of intellectual property and its clinical assets are licensed from Basel, Switzerland-based Novartis AG and Stanford University in California.

The Series B financing was led by San Diego-based Novel Bioventures, and included investments from chairman George Rathmann and CX Venture Group, as well as Series A stockholders, New York-based Allen & Co. and Boston-based MPM Capital.