Novel Islet Transplant Drug is Suspended in Human Trials—Anti-CD154 Kept Diabetic Monkeys off Insulin
On October 21, Biogen announced that it was suspending several trials of its anti-CD154 drug because of blood clotting.
"This is a precautionary measure, based on [blood clotting] events that were encountered in nondiabetic patients," says Bernhard Hering, MD, head of the University of Minnesota's islet transplantation program and anti-CD154 researcher. "The anti-CD154 islet transplant protocol has also been temporarily suspended, pending further FDA review of the anti-CD154 antibody in consultation with an expert panel."
A Disappointing Turn of Events
Kathryn Bloom, company spokesperson for Biogen, declined to divulge the number of patients affected by blood clotting episodes. Bloom did say, however, that no one died while taking anti-CD154. One patient who took anti-CD154 earlier this year but was switched to another drug, did die. Bloom declined to elaborate whether the patients who suffered the life-threatening blood clots were receiving the drug at a specific medical center or which dosage levels were involved.
This turn of events has to be a major disappointment to people like Hering who in the August issue of DIABETES HEALTH ("Transplant Expert Excited About Anti-CD154," p. 24) called work with anti-CD154 a "very exciting project."
Diabetic Monkeys Were Kept Free of Insulin Injections
In its August issue, DIABETES HEALTH reported on studies on six monkeys who had their pancreases removed and islets donated from other monkeys ("The Holy Grail of Islet Research?"). The monkeys received monthly injections of anti-CD154 and no other antirejection drug. Anti-CD154 kept the transplanted islets working and kept the monkeys free of insulin injections and other harmful immunosuppressive drugs for one year.
The University of Miami's Diabetes Research Institute (DRI), which performed the research on the monkeys, called anti-CD154 a "significant breakthrough in islet transplantation." Camillo Ricordi, MD, one of the lead authors of the anti-CD154 study, earlier stated that there is evidence that anti-CD154 could "re-educate the immune system," so that you could discontinue treatment with the drug and still have tolerance of the transplant.
"It seems that it is possible to discontinue treatment [with anti-CD154] and continue to have grafts functioning," he said.
High Hopes Now Face a Roadblock
Jim Vincent, chief executive officer for Biogen, says that determining whether the blood clotting events were connected to anti-CD154 or not is very complicated.
"In the interests of patient safety," says Vincent, "we have asked the investigators participating in the affected phase II trials to stop dosing patients at this time."
There is still some hope that anti-CD154 trials will resume, but the optimism of a few months back seems to have given way to making contingencies for the future of islet transplantation tolerance.
"I remain optimistic for the future of anti-CD154, but at the same time, we will continue to test alternative approaches," says Ricordi.
Biogen said it is working closely with the FDA on reviewing data and determining when trials could be resumed.Click Here To View Or Post Comments