Optimization of Donor-Recipient Matching in Lung Transplantation

Lung transplantation is the curative treatment for end-stage respiratory failure involving highly selected patients. In 2018, the International Transplant Registry counts 69200 lung transplants among 260 transplant centers. Between 2010 and June 2017, the 3-month survival rate of patients after lung transplantation is 90%. The causes of early death are primary graft failure, renal failure, infections, acute rejection (cellular or humoral), surgical complications. The median survival is 6.7 years and the median conditioned survival at 1 year is 8.9 years. Bronchiolitis obliterans is the leading cause of death after 1 year; it affects 10% more patients each year and peaks at 5 years at more than 50% of transplanted patients. These results encourage transplant professionals to continue their efforts to improve the prognosis of transplantation. Among these, the optimization of graft matching, taking into account the characteristics of the donor and the recipient, constitute a relevant avenue of study. Several donor characteristics seem to play a role in the prognosis of the transplant. Survival at 12 months is significantly worse when the donor's age is greater than 50 years. There does not appear to be a significant difference in donor cause of death. Recipients of a graft exposed to smoking ≥ 20 pack-years have a 3% and 1.5% decreased survival at 1 and 5 years postoperatively.

Similarly, the 5-year survival of patients with conditional 1-year survival is poorer in case of other toxic exposures such as alcohol, cocaine, crack or marijuana. Analysis of international registry data also suggests a negative association between post-transplant survival and donor hypertension and diabetes. However, the biological mechanisms by which these factors affect survival remain unknown. Graft ischemia time is significantly associated with survival with a 5-year survival of 70% and 65% for grafts exposed to ischemia ≥ 4 hours or less. The cumulative effect of donor hypertension and ischemia time are appreciated by the fact that the best postoperative survival is observed in donors without hypertension and graft ischemia time ≥ 4 hours. Graft size is also associated with post-transplant prognosis, in front of a significant decrease in survival for patients with emphysema, chronic obstructive pulmonary disease, alpha-1 antitrypsin deficiency, transplanted with a smaller graft size.

This result is not found in patients transplanted for pulmonary fibrosis. One study has also suggested the negative role of a gender mismatch between donor and recipient on post-transplant survival, but there is currently no clear explanation for this result. The presence of antibodies to the recipient's HLA system [DSA (donor-specific antibodies)] in pre-transplant is a risk factor for hyperacute rejection and chronic graft dysfunction. Thus, the choice of matching between the donor and the recipient appears complex in view of the number of criteria to be taken into account which impact the duration of post-transplant survival in the short and medium term. The objective of the project is to develop a decision support tool, using artificial intelligence algorithms, to assist the thoracic surgeon in identifying the patient, among those registered on the team's waiting list, who could benefit most from a bi-pulmonary graft offered by the Biomedicine Agency.