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Campath-1H

 

Campath-1H is an experimental drug treatment for multiple sclerosis, organ transplant rejection and several types of leukemia. The generic name for Campath is alemtuzumab.

Campath-1H works by destroying the body's T cells which are believed to be responsible for initiating the destructive process seen in multiple sclerosis. In one small trial of 27 people with Secondary Progressive MS (SPMS), the drug was found to virtually eliminate the formation of new lesions and the inflammation associated with the disease for at least eighteen months. These results were demonstrated by MRI scans.

For 14 of these volunteers, the progress of their disease initially appeared to be completely halted. In the remaining 13, however, their MS symptoms continued to worsen even in the absence of new inflammatory lesions. MRI studies have discovered that the trial subjects, whose disease continued to progress, were the ones that had the greatest amount of existing lesions and brain atrophy. Unfortunately, as time goes on, it appears that even some of those people whose progression appeared to have been arrested by the drug are now beginning to deteriorate as well. These results have led Campath's researchers to make several important inferences:

As a result, a new clinical trial of Campath-1H taking volunteers with early relapsing-remitting MS has begun. The hope is that, if inflammation can be stopped from the outset of the disease, then the progressive phase of the disease will never happen. The trial will compare Campath-1H with Rebif, and be tested on 180 people in the USA and Europe. The trial is called CAMMS223 and more details are listed below. It is expected that preliminary results from this trial will be available in 2006.

Side-effects

Campath-1H appears to be reasonably well tolerated despite the fact that it kills T cells. In theory, this should leave people seriously immuno-compromised but, in reality, few serious infections were encountered during the trials and no one died.

One serious side-effect was that one third of the trial subjects developed autoimmune thyroid disease (Graves disease). Despite the seriousness of this condition, it is relatively easily managed with thyroxin supplementation and most people with MS would happily exchange multiple sclerosis for Graves disease.

Another noted side-effect was that most volunteers experienced a temporary worsening of their symptoms immediately following their first infusion of the drug.

How Campath-1H works

Campath-1H is something called a humanised anti-CD52 monoclonal antibody. I will try to explain what this means.

Antibodies are small proteins produced by the immune system that stick to small sections of other proteins called epitopes. Proteins containing such epitopes are called antigens. Once attached to an antigen, other aspects of the immune system destroy the cell to which it belongs. Antibodies are extremely specific to particular antigens and will usually only stick to a single one. The immune system usually targets antigens belonging to viruses, bacteria and other unwelcome invaders but it can also attack the body's own cells in autoimmune diseases.

Because antibodies are so specific, researchers have looked at engineering antibodies to disable specific cells in the human body. These are known as monoclonal antibodies and have been called "magic bullets". Campath-1H is just such a monoclonal antibody. It is designed to latch onto cells expressing a protein called CD52 thereby killing them.

CD52 is a type of protein known as a leukocyte antigen. It is expressed on the surface of several types of white blood cells (leukocytes) including lymphocytes (which include T cells), macrophages, monocytes and thymocytes (immature lymphocytes). Campath-1H has been shown to be very effective at destroying T-cells, the cells responsible for initiating the damage in multiple sclerosis. CD52 is also expressed on the cells lining the male reproductive tract. I am unaware whether Campath-1H has any implications for male fertility.

After the initial infusion with Campath, the body's T cell population takes many years fully to regenerate. To make up for the lost immune function, reconstituted lymphocytes of a kind that weren't associated with the disease process in MS were given to the trial volunteers (Th2 cells).

It is thought that because the Campath-1H treatment moves the body's immune response away from a Th1 type of response, one third of the volunteers developed antibodies to a protein found in the thyroid organ (the thyrotropin receptor) and thus developed autoimmune thyroid disease.

Miscellaneous

Campath-1H has been approved by the US Federal Drug Authority for the treatment of chronic lymphocytic leukemia. It has been developed by Millennium Pharmaceuticals and ILEX Oncology. Schering AG and its US affiliate, Berlex Laboratories (the makers of Betaseron), have exclusive world-wide marketing rights.

The CAMMS223 Campath-1H Trial Protocol

Study Title: A Phase II, randomized, open-label, three-arm study comparing low- and high-dose CAMPATH® and high-dose Rebif® (interferon beta-1a) in patients with early, active relapsing-remitting Multiple Sclerosis (MS).

Study Description: This is a Phase II, randomized, open-label, three-arm study comparing low- and high-dose CAMPATH® and high-dose Rebif® in patients with early, active relapsing-remitting Multiple Sclerosis (MS) who have not been previously treated with immunotherapies other than steroids. Patients will be split equally between the three types of treatment.

Inclusion and Exclusion Criteria: The following are selected inclusion and exclusion criteria.

Please discuss your involvement in this clinical trial with your physician.

Selected Eligibility Criteria
Patients must meet all of the following criteria for admission into this study:

Selected Exclusion Criteria
Patients who meet any of the following criteria will be excluded from study admission: Study Site Locations

USA - Click here for a full list of sites
UK - Addenbrooke's Hospital, Cambridge
Croatia - Zagreb
Italy - Milan

Campath-1H links:

The Story of Campath
David's experience with Campath-1H for MS
Campath Patient's Site
Early Use of Campath in MS May Decrease Disability
Campath Clinical Data in Multiple Sclerosis
Campath-1H in multiple sclerosis
MRI after Campath-1H treatment for SPMS (1997)
Campath-1H and autoimmune thyroid disease in MS
Campath-1H exposes 3 mechanisms underlying MS
Transient increase in MS symptoms with Campath-1H
Is Campath-1H effective in treating MS?
Pharmacokinetics of Campath-1H
Campath (Alemtuzumab) For Injection
Alemtuzumab (Millennium/ILEX)
Patient Experience of the Drug

News stories on Campath-1H:

Campath-1H (1999)
More On Campath-1H (2002)
Campath-1H/Clinical Trial (2002)
Leukaemia and MS (1999)
Monoclonal Antibodies (2001)
Two PwMS Using Campath-1H
Woman w/MS - Campath-1H


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