So...what did they do again?
The researchers removed CD34+ cells from the patients bone marrow and infected it with the Maloney retrovirus (MFG) in order to correct the non-functioning gene. Thus, the non-functional gamma-c chain of these patients was corrected to function like a normal gamma-c chain. The researchers then took the corrected cells and returned them to the patients.
Did it work?
Yes. The results show a dramatic increase in a variety of major immune system cells. Specifically, figure 2 shows that the number of overall T-cells has incresed dramatically.
Notice how the CD3+, CD4+, and CD8+ lines shoot upwards virtually exponentially. In addition, both B cells (CD19+) and NK cells (CD16+, CD56+) also have similar growth rates. One of the most amazing parts of this trial is the fact that it took only 270 days to see this dramatic change. In essentially one year, these kids were able to rebuild their immune systems.
Is this better than past treatments?
Very much so. One of the best graphical representations of why this is so is seen in Figure 4 - Part B.
This figure shows the amount of antibodies produced by the immune system. Levels of IgG, IgA, and IgM have matched, or have come close to matching, the levels found in a group of control patients. Antibodies have also been produced to combat tetanus, diphtheria, and polio. So, what's so special about this? In the past, patients who received bone marrow transplants did not produce antibodies. Obviously, this gene therapy trial produced far more positive results. Now, these patients will have a proper immune response when they are exposed to both viruses and bacteria.
Where are they now?
Both patients left protective isolation after approximately three months of treatment. After an 11 month analysis, both patients appear to be growing well. No side effects (of any kind) have been reported. Basically, both patients have achieved a nearly perfect recovery in less than a year! On a third patient, similar positive results have been achieved after 4 months of treatment. Drs. Cavazzana-Calvo et. al. have BURSTED THE BUBBLE ON SCIDs!!! Of course, long-term analysis must be completed in order to see the duration of this treatment.
Click "Forward" to read a phenomenal essay by John Tucker on the benefits and concerns of gene therapy.