Monday, December 20, 2010
Monday, November 29, 2010
Two weeks ago brought good news and bad news for gene transfer. First the good news. New England Journal of Medicine beatified a new gene transfer strategy for Wiskott-Aldrich Syndrome (WAS). WAS is a primary immunodeficiency that primarily affects boys. It is thus in the same family of disorders that have been, in varying degrees, successfully addressed using retroviral gene transfer. Like other immunodeficiencies, this represents relatively low hanging fruit for an approach like gene transfer, because scientists can access and target stem cells, and because corrected cells should be at a selective advantage for survival compared with uncorrected cells.
The NEJM article reported clinical, functional, and molecular outcomes for two boys in a trial based in Germany. Briefly the two boys were given a type of chemotherapy (in order to make space for genetically corrected cells), and then transplanted with “corrected” blood stem cells. The corrected blood stem cells contained a viral vector similar to those used in previous gene transfer trials of primary immune deficiency. The team saw: 1) stable levels of genetically corrected stem cells that expressed the WAS protein (indicating the genetically modified cells “took,” and produced WAS; 2) recovery of the function of a variety of immune cells; 3) reduction of disease symptoms, including improvement of eczema, and reduced severity of infections.
The article exhaustively ruled out events that have occurred in other, similar gene transfer trials in which children developed leukemias from the vector. Now the bad news. The same day NEJM published the results, American Society of Gene and Cell Therapy (the largest professional society devoted to gene transfer) released a statement saying that the German team just announced “a serious adverse event in a gene therapy trial for Wiskott-Aldrich syndrome (WAS)”- one of the ten children in the German trial developed a leukemia.
And so continues the saga of gene transfer: three steps forward, one back. (photo credit: vk-red 2009)
Monday, September 20, 2010
Wednesday, August 4, 2010
Thursday, June 17, 2010
They provide a very critical view of these clinics and the practice of offering nonvalidated stem cell interventions to large numbers of patients outside of clinical trials- a view that readers of this blog will recognize as one that I share: "those who travel to other countries for stem cell treatments enter into a sort of medical Russian roulette." I would add: they pay large sums to shady characters for the privilege.
The back end of the article takes issue with commentators who have offered a quasi-defense of stem cell tourism, viewing stem cell development as analogous to surgical innovation. These commentators have thus defended the idea of offering stem cells outside the trial context. According to the Cohens, these commentators "do not explain in what respects these interventions resemble surgical procedures and do not furnish reasons why clinical trials are not possible for them."
There is an intriguing theme in this article that ties in with my recent Science article. Namely, the Cohens are careful to point out that there are many legitimate stem cell scientists in Russia and India that have called on their governments to regulate stem cell clinics because their activities harm the reputation of unaffiliated stem cell researchers in the same country. More on how stem cell scientists have attempted to draw boundaries between their own work and that of these clinics in my next post... (photo credit: Alex McGibbon, (courtesy Banksy), 2006)