*Purpose: Donor derived cell free DNA (dd-cfDNA) is increasingly being utilized to discern the presence of rejection in kidney transplant recipients (KTRs). There continues to be a lack of guidance for therapeutic interventions for pre – existing and de novo HLA donor specific antibodies (DSA), the presence of which portends to worse graft outcomes in KTRs. Given dd-cfDNA can be utilized to risk stratify and detect the presence of incipient rejection, we sought to ascertain correlation between dd-cfDNA and DSA.

*Methods: We performed a retrospective analysis involving KTs done between 2017 and 2020. Demographics, clinical data and DSA data with concomitant dd-cfDNA (Allosure, CareDx) measurements were collected via the electronic health record. Statistical analysis included Pearson correlation.

*Results: We identified a total of 188 patients who had HLA antibody and dd-cfDNA measurements. Median age at transplantation was 54 years (IQR 43-63), with 42% being female and 45% African-American. Majority (77%) were deceased donor kidney transplants with 25% having 2 or more previous kidney transplants. Levels of de novo and pre-transplant DSA correlated positively with levels of dd-cfDNA (r=0.67 ; r=0.34 respectively ; Figure 1). Class II DSAs demonstrated a better correlation with dd-cfDNA for both de novo and pre-existing subtypes (r=0.73 ; r=0.38 respectively; Figure 2).

*Conclusions: A positive association between DSA and dd-cfDNA exists, with a higher correlation with class II DSAs- this being the largest study to examine this association. Dd-cfDNA could be utilized for monitoring for incipient rejection in patients with pre-existing and de novo DSA, prompting expedient allograft biopsy and management. Further studies need to be done to elucidate the correlation of the combination of DSA and dd-cfDNA with clinical outcomes.

« Back to 2022 American Transplant Congress