An Analysis of Gastrointestinal Graft Versus Host Disease (GVHD) in Bone Marrow Transplant (BMT) Patients in the Era of Short Tandem Repeat (STR) Chimerism Testing - Is it Time to Stop Hedging?

Document Type

Conference Proceeding

Publication Date

3-1-2024

Publication Title

Lab Invest

Abstract

Background: GVHD is estimated to occur in 40-50% of BMT patients and is potentially life threatening. Histologic evaluation of GI biopsies to assess for GVHD is often difficult and frequently requested. Short tandem repeat (STR) chimerism testing has emerged as a clinical adjunct for diagnosing and monitoring GVHD, but is often performed on blood or bone marrow (B-STR) and data on its correlation with morphology and tissue STR (T-STR) results on GI biopsies is limited. The purpose of this study is to evaluate a large cohort of BMT patients and correlate B-STR testing with GI biopsy findings and T-STR testing results. Design: Results of STR testing performed on blood, bone marrow and tissue between October 2021 and July 2023 by our hospital’s HLA laboratory were reviewed to identify a cohort of 68 BMT patients transplanted December 2008-April 2023. Relevant clinical information was collected. Available GI surgical biopsies with discordant concurrent STR results (within 20 days of biopsy) were also reviewed. T- STR chimerism testing was performed on FFPE tissue sections on a subset of 6 discrepant results. Statistical analysis was performed. Results: Table 1 compares the clinical features, STR testing results and biopsy results between the STR positive and negative cohorts. There was a significantly higher incidence of ALL/AML/MDS in the STR positive cohort. A total of 84 biopsy results (53 GI and 31 skin) were reviewed on which 74 (88%) had both biopsy findings and concurrent STR results. 44 (59.5%) had concordant biopsy and STR results while 30 (40.5%) had discordant results. Of discordant results, 73% had biopsy findings of GVHD with negative B-STR testing. In a subset of 6 discordant cases, T-STR testing was performed on FFPE tissue sections. Two of 2 (100%) biopsy confirmed GVHD/B-STR negative cases tested positive for chimerism in tissue while 3 of 4 (75%) biopsy negative/B-STR positive cases tested negative for chimerism in tissue. Conclusions: Our study demonstrates that STR testing presents a potentially useful adjunct to the diagnosis and monitoring of GVHD, but, when performed on blood and bone marrow samples, the overall concordance with GI biopsy diagnosis is modest (59.5%). When T-STR testing was performed on discordant tissue samples, 83.3% of biopsy results were concordant with T-STR testing, suggesting a multimodal approach for diagnosis may be necessary.

Volume

104

Issue

3

First Page

S741

Last Page

S742

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