Assessing the Likeliness of "Unlikely" - An Institutional Analysis of Graft Versus Host Disease (Gvhd) in Solid Organ Transplant Patients Correlating Short Tandem Repeat (Str) Chimerism Testing with Clinical and Available Pathologic Findings

Document Type

Conference Proceeding

Publication Date

3-1-2024

Publication Title

Lab Invest

Abstract

Background: Graft versus host disease (GVHD) is a potentially serious complication of transplantation; however, the risk in solid organ transplant (SOT) is considered to be very low. As an adjunct, Short Tandem Repeat (STR) chimerism testing has evolved as a surrogate marker for GVHD, but is often performed on blood and questions remain whether these samples are reflective of pathologic and clinical findings. As such, this study aims to address these questions by reviewing a large cohort of STR testing results to examine the rate of positive testing and correlate with clinical and biopsy findings in SOT patients. Design: Results of clinical STR chimerism testing between December 2019 and June 2023 performed and reported by our hospital’s HLA laboratory were reviewed. Relevant clinical data was collected including transplant type and date, clinical symptoms and management for GVHD, STR and biopsy results. Statistical analysis was performed. Results: 65 patients with a history of SOT and STR testing (blood or bone marrow) results were reviewed. Testing included 126 STR tests (123 (97.6%) blood, 2 (1.6%) each bone marrow, CSF and skin, 1 (0.8%) each stomach and colon) with an average of 1.9 tests per patient (median 1, range 1-29). In this period, 5 patients (7.7%) tested positive and 60 (92.3%) tested negative. Table 1 summarizes relevant clinical characteristics, STR results and biopsy findings between the STR positive and negative cohorts. There were significantly more multiorgan transplants in STR positive versus negative. Similarly, STR patients were significantly more likely to have GVHD findings and be labeled GVHD clinically. In the STR positive patients, the mean time from transplant to positive test was 41 days (range 6-82 days) and the mean percent donor detection ranged from less than 1 to 52%. In the 12 positive tests, chimerism was detected in blood (8 (66.7%)), CSF (2 (16.7%)), bone marrow (1 (8.3%)) and tissue (1 (8.3%)). All 5 STR positive SOT patients had clinical symptoms of GVHD and, of the 3 with concurrent biopsies, 2 (both skin) had histologic features of GVHD. Conclusions: Here we report a cohort of SOT patients with STR results and correlate them with clinical and pathologic findings of GVHD. While the rate of STR positive was low (7.7%), results correlated with clinical evaluation and with biopsy findings. There were significantly more STR positive results in patients with liver and multiorgan transplant. As such, STR testing may be a useful surrogate marker for these patients.

Volume

104

Issue

3

First Page

S887

Last Page

S888

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