Say there is a person with multiple sclerosis (MS) who meets all the criteria for a clinical trial of Tovaxin. Her name is Lexie. Let’s take a look and see what it takes to make Tovaxin for Lexie:
Step 1: Determine if Lexie Can “Make” VaccineThe very first step in making Tovaxin for Lexie is to collect a blood sample. With this sample, it can be determined if she has the right kind of cells to make the vaccine. Let me explain. A company named Opexa has created a test that can detect the myelin reactive T-cells (MRTCs) that are attacking the myelin of a person with MS. However, in some people, these cells cannot be detected, even though we all have them.
There could be several reasons why Lexie’s MRTCs might not be detected by this test:
- The test may be lacking the ability to detect the exact proteins against which Lexie’s specific MRTCs are working. Right now the test reacts to 109 different “peptide fragments” (pieces of protein called “epitopes”) from the three primary myelin proteins that have been implicated in MS.
- Lexie may have levels of MRTCs that are too low to be detected. One reason for this could be that the MRTCs were reduced by something like a big dose of Solu-Medrol. It could also be that there are just times when there are not very many MRTCs in circulation and times that there are more.
Bottom line here – if Lexie has MRTCs that can be detected, then the process moves forward. If not, then Tovaxin cannot be made for Lexie at this time. Right now it seems that more than 60% of people tested have enough detectable MRTCs to make Tovaxin.
Good news for Lexie! She has detectible MRTCs and the process moves forward…
Step 2: Isolate and Expand MRTCsOnce the MRTCs are detected in Lexie’s blood sample, they are separated from all of the other immune cells and “expanded” to make millions of them. This is done by culturing them with myelin antigens and other immune cells, basically tricking the MRTCs into thinking that there is a whole bunch of myelin that they need to attack. Remember, for some reason the MRTCs of a person with MS think that the myelin is an antigen (an invader) and see it as their job to attack it. To do this, they replicate themselves into a veritable army of MRTCs.
These MRTC will be expanded in the laboratory until enough of them are available to make five doses of the vaccine for the first year. The first dose will contain between 30 and 45 million MRTCs. This process takes from 40 to 60 days before there are enough MRTCs.
Step 3: Attenuate (Weaken) the MRTCsOnce it has been determined that there are enough MRTCs to use for a vaccine, the MRTCs are then exposed to radiation. This “weakens” them so that they cannot attack the myelin, but they still “look the same” on the outside.
The radiation used to weaken (or “attenuate”) the MRTCs poses no danger to the person when these cells are reintroduced. The MRTCs are not “radioactive” when they are injected.
Step 4: Inject the Vaccine Into LexieThe day is here. Lexie goes into her neurologist’s office and she is “vaccinated” with her dose of Tovaxin. It is a simple subcutaneous injection into her arm. That is it. She probably won’t have much of a reaction at all, except maybe a little irritation at the injection site.
Now What Happens?Lexie will probably be given four additional doses of the same vaccine and monitored – her first blood collection is enough to make vaccines for a year. In a year, her blood will be taken again and tested for MRTCs and a new vaccine of Tovaxin will be made for her in exactly the same way. It is necessary to make a new vaccine, as there will probably be an “epitope shift” in her MRTCs. This simply means that her MRTCs have changed slightly so a new somewhat modified vaccine is required to better combat her MS.
Source: Correale J, Farez M, Gilmore W. Vaccines for multiple sclerosis: progress to date. CNS Drugs. 2008;22(3):175-98. Opexa Therapeutics website.
Correale J, Farez M, Gilmore W. Vaccines for multiple sclerosis: progress to date. CNS Drugs. 2008;22(3):175-98.
Opexa Therapeutics website.