Kidney Week

Abstract: PO2394

Development and Clinical Experience with a Cell-Free DNA Monitoring Algorithm for Kidney Re-Transplants

Session Information

• Clinical and Immunologic Predictors of Post-Transplant Outcomes
  October 22, 2020 | Location: On-Demand
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 1902 Transplantation: Clinical

Authors

• McKanna, Trudy, Natera, Inc, San Carlos, California, United States

Trudy McKanna,

• Ahmed, Ebad, Natera, Inc, San Carlos, California, United States

Ebad Ahmed,

• Simmons, William, Natera, Inc, San Carlos, California, United States

William Simmons,

• Pastrick, Meredith, Natera, Inc, San Carlos, California, United States

Meredith Pastrick,

• Gauthier, Philippe M., Natera, Inc, San Carlos, California, United States

Philippe M. Gauthier,

• Keen-Kim, Dianne, Natera, Inc, San Carlos, California, United States

Dianne Keen-Kim,

Background

The presence of donor-derived cell-free DNA (dd-cfDNA) in blood samples from kidney transplant recipients can be utilized as a biomarker for transplant rejection.¹ Failure of the original allograft due to rejection, infection, or recurrent disease leads to retransplants, observed in up to 10% of all kidney transplant patients.^2,3 In these cases, the original transplanted kidney is generally left in-situ. A rapid, accurate, and noninvasive diagnostic test assessing dd-cfDNA using single nucleotide polymorphism (SNP) based massively multiplexed PCR (mmPCR) test (Prospera^TM) may be utilized to detect allograft rejection.¹ Among retransplant patients, this test can detect both donor fractions in the plasma, when both the new and previously transplanted kidneys are releasing cfDNA.
Objective: To present the clinical performance of the SNP-based mmPCR test analysis algorithm on samples from patients with kidney retransplants in which allografts are present from two genetically distinct donors.

Methods

Plasma samples from a cohort of second transplant patients were collected and processed as described previously.^1,4 The SNP-based mmPCR test algorithm is designed to detect all donor fractions in the plasma, when both the newly transplanted kidney as well as previously transplanted kidney(s) may be releasing cfDNA into the plasma. This algorithm estimates the total fraction of DNA due to all donor fractions combined.

Results

We present the clinical performance of patients with a second kidney transplant by this retransplant algorithm. In our dataset to date, no significant difference in dd-cfDNA levels compared to single allograft recipients was observed, suggesting limited cfDNA shedding from the initial kidney transplanted. Our results confirm the ability of this assay to analyze and quantify dd-cfDNA levels in kidney retransplant patients.

Conclusion

Our results indicate that performance of this SNP-based mmPCR test is preserved in repeat transplant recipients. Non-invasive assessment of dd-cfDNA in retransplant patients may be used to detect the presence of injury or rejection of the transplanted organ at an early stage, facilitating physician management around change of anti-rejection therapy.

Funding

• Commercial Support – Natera, Inc