Companies use different approaches for transplanting islets
At ENDO 2022, Dr. Jaiman presented results for three patients who received pancreatic precursor (PEC-01) cells derived from ViaCyte’s proprietary pluripotent stem cell line. The cells are housed in an open delivery device about the size of a standard bandage to allow direct vascularization and are implanted in a patient’s forearm. An earlier version of the device was used in the two patients in “The Human Trial.”
All three patients experienced improved blood glucose levels with lower daily insulin doses and a rise from undetectable C-peptide to levels above 0.3 ng/mL. Of the three, the best results were seen in a 52-year-old woman with type 1 diabetes for 36 years complicated by hypoglycemic unawareness. At 1-year post transplant, her hemoglobin A1c dropped from 7.4% to 6.9%, and time in range [of ideal blood glucose] from 55% to 94%, plus she had a reduction in daily exogenous insulin use of 70%. However, at 18 months her time-in-range had dropped to about 75%.
“We are watching very closely to see what this means,” Dr. Jaiman said.
Further optimization of the approach is planned. “We’re still waiting on the bulk of the data and analyzing it ... We do realize this is a journey but we’re very excited by where we are,” she enthused.
In February 2022, ViaCyte announced it had teamed up with CRISPR Therapeutics to develop an allogeneic, gene-edited stem cell-derived product designed to produce insulin while at the same time evading the immune system.
Preliminary data from another company, Sernova, using a pouch device were presented at the 2022 annual scientific sessions of the American Diabetes Association by Piotr J. Bachul, MD, of the Transplantation Institute at the University of Chicago.
The Sernova Cell Pouch System containing cadaver islets was successfully transplanted into the abdominal wall of six of seven patients. After waiting a month to allow for vascularization, the cells are then placed into the pouch (as opposed to ViaCyte’s method where they are implanted together). The first three patients achieved islet cell graft function – with positive C-peptide – for up to 1 year, although all also required supplemental transplants into the portal vein to achieve insulin independence.
In May 2022, Sernova announced a partnership with Evotec to develop a product that will combine induced pluripotent stem cell (iPSC)-based beta cells for use with the Cell Pouch System.
Clinical testing is scheduled to begin in 2024, a Sernova representative told this news organization.
And as reported earlier in June, findings from Vertex Pharmaceuticals showed success in two patients who received that company›s investigational allogeneic stem-cell derived islets (VX-880), with the first person completely insulin independent 9 months post transplant.
In contrast to the other two companies, Vertex’s approach is to transplant the cells directly to the hepatic portal vein rather than into a subcutaneous pouch.
“The only space that has ever worked efficiently for islets is the liver because they immediately get blood. ... The subcutaneous space is an interesting place, but the problem is it’s not very well vascularized,” James F. Markmann, MD, PhD, chief of the division of transplant surgery at Massachusetts General Hospital, Boston, who worked on the Vertex trials, told this news organization.
However, the Sernova representative countered: “With the Cell Pouch transplant, not only can surgeons avoid the risks associated with [hepatic] portal vein infusion – including immediate blood-mediated inflammatory reaction, which is known to kill a large proportion of infused islets – but also liver pathologies.”
Furthermore, the cells remaining in the pouch “may be entirely removed from the patient in the event of a subsequently detected cell quality issue,” which isn’t possible with cells delivered into the portal vein.
“I think it will be interesting how it plays out,” Dr. Markmann said, referring to the field as a whole.