Results of the novel clinical protocol were presented today by Kenneth R. McCurry, M.D., assistant professor of surgery at the University of Pittsburgh School of Medicine, at the American Transplant Congress (ATC), the joint scientific meeting of the American Society of Transplant Surgeons and the American Society of Transplantation.
With more than a year of follow-up in many patients, Dr. McCurry found that even those patients who have been able to reduce their medications to one pill a day benefit from the approach, which differs from the conventional twice-a-day triple-drug therapy, said Dr. McCurry.
"Bombarding the immune system with several very potent drugs has done little to improve the outcomes for lung transplant recipients, who continue to have poor survival - about 75 percent at one year - compared to other organ recipients. Moreover, the drugs have not done well to prevent chronic rejection, which affects about half of lung transplant patients by five years and usually results in organ failure and death. These bleak outcomes have motivated us to introduce an approach that we hope will enhance long-term survival, reduce the rates of complications associated with these drugs and improve quality of life," said Dr. McCurry, who also is director of lung and heart-lung transplantation at UPMC.
The approach is the only one of its kind involving lung transplant patients, in whom studies that seek to reduce anti-rejection drugs are rarely performed out of fear that the lungs, already the most vulnerable organ to rejection, would succumb to an irreversible immune system attack, placing patients at risk for death. Ironically, lung recipients have the greatest incidence of immunosuppression-related complications, such as infection and chronic kidney dysfunction, providing incentive to search for alternative immunosuppression approaches.
UPMC's clinical protocol involves a one-time dose of a drug that depletes T cells - key immune system cells that are known to target the donor organ - that is given just before transplantation. Following transplantation, patients are treated with just one anti-rejection drug, tacrolimus, that is administered at reduced levels. Since many lung recipients are treated with prednisone for their underlying disease, the steroid is continued after transplant but at a negligible dose, 5 mg compared to 20 mg.
The rationale is to treat patients with as little immunosuppressive medication as possible following the transplant while preventing injury to the graft by the recipient's immune system.
Since June of 2002, more than 80 patients have been treated under the protocol. At ATC, Dr. McCurry reported results in many of these patients, including 31 who have been followed for more than a year after transplant, several for nearly two years.
The first 38 patients were given a pre-transplant drug called Thymoglobulin. One-year survival for these patients is 87 percent. The remaining patients received Campath, which appears to deplete T cells more broadly and for a longer period of time. Acute rejection episodes have been less in the Campath patients reported on at ATC compared to those who received Thymoglobulin. Twenty-five of the 38 Thymoglobulin patients had rejection episodes greater or equal to Grade 2, compared to two of the first10 Campath treated patients.
There were no opportunistic infections or related complications in the patients treated with Campath; a small percentage of the Thymoglobulin patients developed either cytomegalovirus (8 percent), the bacterial infection Nocardia (8 percent) or post-transplant lymphoproliferative disorder (3 percent), rates that were comparable to conventionally treated patients.
One-year follow-up results are not yet available to compare survival between the Thymoglobulin-treated and Campath-treated groups. However, the overall patient survival for Thymoglobulin-treated patients is 84 percent while in the Campath-treated patients it is 98 percent.
"We are encouraged by these preliminary results. What remains to be seen is if our approach will have an impact on chronic rejection," said Dr. McCurry.
"At this point, I think we can say that the standard multi-drug approach to immunosuppression may be excessive and leads to increased complications. Moreover, our promising early results suggest that altering the approach and reducing immunosuppression is not as risky as some would have guessed. The next step we should consider is a multi-center, randomized trial. Only with that kind of data might the transplant community embrace the notion that radical change is warranted," noted Dr. McCurry.
"Personally, I think our approach will presage significant improvements in outcomes for lung transplantation," he added.
NOTE TO EDITORS: Abstract # 404, "Outcomes Following Pre-transplant T-cell Depletion with Thymoglobulin or Campath in Human Lung Transplantation," is being presented at 2:10 p.m. on Sunday, May 16. The American Transplant Congress will be holding a press briefing with Dr. McCurry at 3:30 p.m. that day. The press room is located in Room 107 and Room 108 of the John B. Hynes Convention Center in Boston. Beginning at 10 a.m., Sunday, May 16, the press room phone number is 617-954-3034. For more information about the press briefing, contact Steven Schiff at 610-449-8056. To schedule interviews with Dr. McCurry call Lisa Rossi at 412-916-3315.