Saturday, August 29, 2009

Update on Gitelman's ATG Phase-II Clinical Trial

Dr. Gitelman at UCSF has started a Phase-II human trial aimed at using ATG to cure (or lessen) type-1 diabetes. The goal of this study is to preserve remaining beta cells for people within 100 days from diagnosis. This study started in August 2007, and is expected to run until June 2011. So far it has enrolled 11 out of an expected 66 patients. It's a four day treatment (in hospital), and 12 follow up visits over a 2 year period. They are recruiting at a total of 9 sites (growing to 13), which are listed in the clinical trial page linked below.

Here is a quick summary of how they hope ATG (Thymoglobulin) will work:

Type 1 diabetes is caused by destruction of insulin-producing beta cells by T cells, part of the immune system. Thymoglobulin is a mixture of different antibodies that target T cells. This mixture includes the anti-CD3 antibody (and anti-CD3 treatments are in Phase-III trials already, having completed successful Phase-I and II trials). The researchers hope that this multi-faceted approach will be even more successful and have a longer lasting effect than with anti-CD3 alone, and may treat diabetes by several mechanisms. First, it lowers the number of T cells, so there are fewer to attack the beta cells. It also seems to alter the T cells remaining behind, rendering them less likely to be destructive. Following this depletion, the T cells that grow back in the following weeks may be reset and have a healthier balance (meaning that a special type of T cells, called regulatory T cells, will help keep the destructive T cells in check).

Using ATG to cure type-1 diabetes is an idea that flows from two sources. The first source is a line of clinical trials aimed directly at curing type-1 with ATG. Eisenbarth's work of long ago, a Phase-I trial done in Europe, etc. But it also has another source, which is Burt's Brazilian research as described below.

Discussion: How to Follow Up Burt?

One of the questions that I'm occasionally asked is this: when will there be a follow up to Burt's Brazilian research? When will there be a Burt, phase-II? This is a natural question, because Burt has -- by far -- the best results of any one. Many patients on that trial went years without using external insulin. No other study comes close. So an obvious question is: how do you move forward with that research.

Burt's research is the opposite of most. Most researchers use the smallest possible doses during phase-I. Phase-I is targeted at safety, so they use small doses to assure safety even at the expense of effectiveness. So for most studies, for phase-II studies, they move forward by raising the dose to try to make a safe treatment a more effective one. But Burt's research is the opposite. The effectiveness is the strongest yet, but there are real questions about safety. So you would NOT follow it up by raising the doses!

One way to follow up Burt's relative success, is by turning down the dose. Trade off a little effectiveness for added safety. Oversimplified a little: Burt's research involves using three drugs (ATG, GCSF, and cyclophosphamide), and reinjecting the patient's own precursor bone marrow cells (previously removed). Dosing with just ATG can be viewed as a "kinder, gentler" Burt. Especially since the cyclophosphamide is the most risky drug of the bunch. (I'll be posting on two GCSF clinical trials in the coming weeks.)

Since I'm a software engineer, I'll use a software analogy: Burt is doing a "hard reboot", Gitelman is trying for a "soft reboot".


One of the complexities of following the research, is that ATG is referred to by many different names by different groups. For example: Thymoglobulin, rATG, hATG, ATGAM, antithymocyte globulin, etc.

The cells that Burt is removing and then reinjecting are sometimes called "precursor bone marrow cells" and other times "adult stem cells".

The lead investigator for this clinical trial is Dr. Gitelman at UCSF. For those of you at Bearskin Meadows: yes, this is the same "Dr. Steve" who is often up there. I'm indebted to Dr. Gitelman for his insights into Burt's research and how it relates to other research, including his own. All mistakes, opinions, and oversimplifications are my own.

Patient oriented information on this trial:

Previous Blog postings on this (blog on ATG) (blog on Burt) (blog on Gitelman)

Web pages (but these need updating): (Gitelman) (Burt)

Clinical Trial records for this study: (Phase-II ATG) (Phase-I ATG) (Burt)

Joshua Levy

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