The Lancet: First report of long-term safety of human embryonic stem cells to treat human disease

PUBLIC RELEASE DATE:

14-Oct-2014

Contact: Robert Lanza rlanza@advancedcell.com 508-756-1212 x315 The Lancet @TheLancet

New research published in The Lancet provides the first evidence of the medium-term to long-term safety and tolerability of transplanting human embryonic stem cells (hESCs) in humans.

hESC transplants used to treat severe vision loss in 18 patients with different forms of macular degeneration appeared safe up to 3 years post-transplant, and the technology restored some sight in more than half of the patients.

"Embryonic stem cells have the potential to become any cell type in the body, but transplantation has been complicated by problems including the risk of teratoma formation[1] and immune rejection"[2], explains lead author Professor Robert Lanza, Chief Scientific officer at Advanced Cell Technology in the USA. "As a result, immunoprivileged sites (that do not produce a strong immune response) such as the eye have become the first parts of the human body to benefit from this technology."[2]

In the two phase 1/2 studies, hESCs were differentiated into retinal pigment epithelium cells [3] and transplanted into nine patients with Stargardt's macular dystrophy and nine patients with dry atrophic age-related macular degeneration, the leading causes of juvenile and adult blindness in the developed world, respectively. No effective treatments exist for either condition, and eventually the light-receiving (photoreceptor) cells of the retina degenerate leading to complete blindness.

All participants were injected with one of three different doses of retinal cells (50 000, 100 000, and 150 000 cells) into the subretinal space (under the retina) of the eye with the worse vision.

The hESC-derived cells were well tolerated for up to 37 months after transplantation. No safety concerns (eg, hyperproliferation or rejection) in the treated eyes were detected during a median follow-up of 22 months. Adverse events were associated with vitreoretinal surgery and immunosuppression, but none were deemed to be related to the hESC-derived cells.

Follow-up testing showed that 10 out of 18 treated eyes had substantial improvements in how well they could see, with 8 patients reading over 15 additional letters in the first year after transplant. Visual acuity remained the same or improved in seven patients, but decreased by more than 10 letters in one patient. Importantly, untreated eyes did not show similar visual improvements.

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The Lancet: First report of long-term safety of human embryonic stem cells to treat human disease