Standing on the shoulders of stem cell gene therapists: history, hyperbole and hope for the future.

A new type of medicine was approved in Europe at the end of May that culminated from the successful convergence of two fields of science: stem cell transplantation and gene therapy. Strimvelis, a patient-specific gene-modified stem cell medicine for ADA-SCID (a fatal immunometabolic disorder similar to the bubble-boy disease), was developed by scientists at the San Raffaele Telethon Institute for Gene Therapy (TIGET) in Milan, then later partnered with GSK. The journey took over 25 years of dedicated work from many groups and involved a pivotal trial with 12 children and their brave families. I was fortunate to be involved on the GSK side of the TIGET alliance from 2010-2015, building upon my previous experiences in gene-modified stem cells during a post-doctoral fellowship in the mid-1990s and at Chiron, which had acquired Viagene, an early gene therapy biotech. I thought it was timely to pick out a couple of observations from the development of Strimvelis to see how these might apply not only for the future of stem cell gene therapy but also be the shoulders for the adjacent CAR-T and gene editing technologies to stand on.