How soon will human embryonic stem cells jump to the clinic?

by Alexey Bersenev on April 16, 2008 · 0 comments

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This question was a subject of the discussion on federal level in USA last week. The main regulatory organization – Food and Drug Administration (FDA), which examines clinical trials and biological products for clinical use, held a meeting last week to discuss all of the issues around the future of embryonic stem cell therapy. Oh god, we have been waiting for it so long! Finally it happened and I have to admit that the discussion seemed to be productive.

The advisory committee, which was made up of 25 independent scientists and FDA researchers, addressed issues of proper animal studies for preclinical testing and how researchers can control the embryonic stem cells for appropriate differentiation – that is, so they don’t form cancerous teratomas.

As we know, FDA was alarmed by a bad experience of gene therapy clinical trials. So, of course, the main point of discussion was a safety issue. One issue raised was how to set up a reliable teratoma assay. Current animal models (mouse/large animals, allogeneic/xeno-) and vitro assays to facilitate embryonic stem cell therapy were discussed.

Three companies, including Geron Corporation , Advanced Cell Technology, and Novocell presented some of their scientific results from preclinical models of ESC-based therapies. All of them could not detect any unexpected teratoma formation after differentiated cells were purified from ESC.

A big question is how many transplanted cells it takes to get a teratoma. Geron’s Lebkowski presented data in which ES cells were spiked into a population of progenitor cells and rodents were monitored for teratomas for twelve months. If ES cells were fewer than 5 percent of the total of two million transplanted, researchers never saw teratomas.

Some of clinically-relevant questions were addressed about ESC transplantation – level of ESC purity, optimal cell dosage and site of implantation, tracking cells after transplantation and manipulation of grafted cells in the recipient.

Committee members worried about their inability to remove cells from patients if they started awry, but a proposal for inserting a “suicide gene” into cells intended for therapy won little enthusiasm; one committee member suggested it could introduce as many risks as it eliminated.
“We should not create too many standards,” urged Jeffrey Chamberlain of the University of Washington School of Medicine. “A quarter of people who get the cells will die of cancer anyway.”


As a result of the meeting, FDA issued 12-page document: “Cellular Therapies Derived from Human Embryonic Stem Cells – Considerations for Pre-Clinical Safety Testing and Patient Monitoring”.

I’d like to pointed out that it was just a first meeting on this level and a lot of questions and issues were raised, but there was no solution. So, to me it seems that ESC-based therapy still has a long way to go. Nonetheless, this year could be essential for ESC therapy and for stem cell business in general, because FDA is in the process of reviewing IND applications for the first human ESC therapy clinical trials, submitted by Geron and Advanced Cell Technology.

By the way, one Asian news already reported about the first infusion of ESC-derived cells into a human patients in 2006 in India and didn’t report about any adverse effects so far.

Quotes: Monya Baker (the Niche)
Blogs reaction:
Gearing for nitty-gritty questions on making safe products from embryonic stem cells (the Niche)
Overview of FDA meeting on embryonic stem cells: cautious movement toward the clinic (the Niche)
FDA mulls embryonic stem cell therapy (the Scientist)

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