Non-Invasive Characterization and Early Detection of Post-Transplant Lymphoproliferative Disorders

Schroers-Martin, Joseph

Oral and Poster Abstracts
Oral
622. Lymphomas: Translational - Non-Genetic: Demystifying the Complexity of the Lymphoma Tumor Microenvironment and Immune Responses

Research, Translational Research, Lymphomas, Non-Hodgkin lymphoma, B Cell lymphoma, Diseases, Aggressive lymphoma, Immunology, Lymphoid Malignancies, Biological Processes, Microbiome, Technology and Procedures, Study Population, Human, Measurable Residual Disease , Molecular testing, Serologic Tests

Joseph G. Schroers-Martin, MD¹, Andrea Garofalo, BS, BA², Shuyu Shi³, Joanne Soo, MD⁴^*, Helen Luikart, RN, MSN⁵^*, Brian J. Sworder, MD, PhD⁶, Jan Boegeholz, MD⁷, Xiaoman Kang, BS⁸^*, Mari Olsen, BS²^*, Chih Long Liu, PhD²^*, Feng Tian, PhD²^*, Annette Skoda⁵^*, Gerardo Gamino⁵^*, Dave Jimil Morales⁵^*, Kathrin Freystaetter, MD⁹^*, Sean Agbor-Enoh, MD, PhD¹⁰^*, Martin Andreas, MBA, PhD¹¹^*, Dan Chambers, MBBS MRCP FRACP MD¹²^*, Maria Crespo-Leiro, MD, PhD¹³^*, Gundeep Dhillon, MBBS¹⁴^*, Maryjane Farr, MD¹⁵^*, Seth Hollander, MD¹⁶^*, Abdallah Kfoury, MD¹⁷^*, Evan Kransdorf, MD, PhD¹⁸^*, Marcel Nijland, MD, PhD¹⁹^*, Jayant Raikhelkar, MD²⁰^*, David Rosenthal, MD²¹^*, Heather Ross, MD²²^*, Stijn Verleden, PhD²³^*, Lorenzo Zaffiri, MD, PhD¹⁸^*, Andreas Zuckermann, MD⁹^*, David Kurtz, MD, PhD^2,24, Yasodha Natkunam, MD, PhD²⁵, Maximilian Diehn, MD, PhD^26,27^*, Kiran Khush, MD⁵^* and Ash A. Alizadeh, MD, PhD²⁸

¹Department of Medicine, Division of Oncology and Hematology, Stanford University, Menlo Park, CA
²Department of Medicine, Divisions of Oncology and Hematology, Stanford University, Stanford, CA
³Dept. of Bioengineering, Schools of Engineering and Medicine, Stanford, CA
⁴Stanford University, Stanford, CA
⁵Division of Cardiovascular Medicine, Stanford University, Stanford, CA
⁶Division of Hematology and Oncology, University of California, Irvine, Irvine, CA
⁷Divisions of Hematology and Oncology, Stanford University, Stanford, CA
⁸Department of Medicine, Division of Oncology, Stanford University, Stanford, CA
⁹Medical University of Vienna, Vienna, Austria
¹⁰National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
¹¹University of Vienna, Vienna, Austria
¹²University of Queensland, Brisbane, Australia
¹³Universitario A Coruña, La Coruna, Spain
¹⁴Division of Pulmonary, Allergy, and Critical Care Medicine, Stanford University, Stanford, CA
¹⁵Heart Failure, Mechanical Circulatory Support and Transplant, UT Southwestern, Dallas, TX
¹⁶Stanford University, Palo Alto, CA
¹⁷Intermountain Heart Institute, Murray, UT
¹⁸Cedars Sinai Medical Center, Beverly Hills, CA
¹⁹University Medical Center Groningen and University of Groningen, Groningen, Netherlands
²⁰Columbia University, New York, NY
²¹Department of Pediatrics, Division of Cardiology, Stanford University, Stanford, CA
²²Toronto General Hospital, University Health Network, Toronto, Canada
²³Katholieke Universiteit Leuven, Leuven, Belgium
²⁴Department of Medicine (Oncology), Stanford University, Palo Alto, CA
²⁵Department of Pathology, Stanford University School of Medicine, Stanford, CA
²⁶Department of Radiation Oncology, Stanford University, Stanford, CA
²⁷Department of Radiation Oncology, Stanford University Medical Center, Stanford, CA
²⁸Stanford University, San Mateo, CA

Background: Post-transplant lymphoproliferative disorder (PTLD) is a feared complication of solid organ transplantation with no standard surveillance strategy. Serial EBV titers provide limited sensitivity for EBV-negative PTLD. Cell-free DNA (cfDNA) is an effective biomarker in lymphomas, and we hypothesized that cfDNA could allow multimodal non-invasive characterization and early detection of PTLD. We evaluated cfDNA-based genotyping, viral detection, and T-cell receptor (TCR) repertoire to characterize and facilitate early detection of PTLD.

Methods: We studied 265 plasma or serum samples from 75 lymphoma patients (pts) from our global consortium of 12 solid organ transplant centers (median 3.5 samples/pt). We profiled serial pre-diagnostic specimens obtained during routine post-transplant care to characterize the window for early non-invasive detection, and post-treatment samples to evaluate response kinetics. We additionally assessed healthy adults without transplant (n=35), and transplant pts in good health (n=13), during acute allograft rejection (n=25), CMV reactivation (n=25), and EBV reactivation without lymphoma (n=18). CfDNA was extracted and enriched via hybrid capture to evaluate 186 B-cell lymphoma related genes (Alig et al Nature 2024), 180 viral species (Garofalo et al Blood 2019), TCR for immune repertoire profiling (Shukla Blood 2020), and common SNPs to assess donor-derived cfDNA.

Results: Clinical Characteristics: Pts underwent heart (53%), lung (29%), kidney (12%), or liver transplantation (6%), with median 810 days between transplant and PTLD diagnosis. Clinical tumor EBER status was 71% EBV+, 23% EBV-, and 6% unknown. Among pts with available treatment data, 93% received initial rituximab, followed by observation (37%) or R-CHOP-like chemotherapy (63%).

Circulating Virome: Higher cell-free EBV levels were observed in PTLD pts as compared to healthy adults or healthy transplant pts. Heart and lung transplant recipients had greater EBV and Anellovirus burden compared to kidney or liver recipients, likely reflecting more intensive immunosuppression. Circulating EBV was higher in patients with EBER+ tumors (p=0.019) and with diagnosis ≤2 years post-transplant (p=0.04). Anellovirus levels were higher in the early post-transplant period with no chronologic association with PTLD, while EBV levels increased in proximity to clinical PTLD diagnosis (≤3 months, p=0.026).

TCR Repertoire: We evaluated circulating TCR clonotypes using SABER and quantified TCR repertoire diversity via Chao1 index. TCR repertoire diversity was similar between PTLD and non-malignant EBV reactivation but lower diversity was seen in a subset of patients with CMV reactivation and acute allograft rejection.

Mutational Profiling: At diagnosis or closest pre-diagnostic timepoint, PTLD pts had a higher burden of missense mutations detected in cfDNA as compared to healthy adults (p=0.0041). As previously observed in PTLD tumors, more coding mutations were observed in cfDNA from EBV- as compared to EBV+ PTLD. Considering mutational signatures, EBV- cases were enriched in SBS84, an AID/SHM signature, while EBV+ cases were enriched in the DNA mismatch repair signature SBS6.

Response Assessment: Among pts receiving risk-stratified sequential treatment (RSST) with initial rituximab monotherapy and available post-rituximab sample, pts achieving durable CR had lower interim ctDNA concentration (n=6, median 6 HGE/mL) as compared to pts requiring chemotherapy consolidation based on radiographic response (n=8, median 53 HGE/mL).

Early Detection: We considered pre-diagnostic samples from pts developing PTLD (n=45). Samples obtained ≤6 months before clinical diagnosis had higher EBV levels (p=0.028) and more frequent coding mutations as compared to more distant timepoints. Mutations were detected in 71% of samples (32/45) at median 58 days prior to diagnosis, suggesting a window of months for early detection.

Conclusions: Multimodal characterization of cfDNA revealed patterns of virome dysregulation and oncogenic mutations preceding clinical lymphoma diagnosis. Non-invasive surveillance via cfDNA is a promising approach in solid organ transplant pts at risk for PTLD, and could also facilitate risk-stratified therapy approaches.

Disclosures: Boegeholz: Takeda Switzerland: Other: travel support. Kurtz: Foresight Diagnostics: Current Employment, Current equity holder in private company, Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Natkunam: Kite Pharma: Research Funding; Leica Biosystems: Membership on an entity's Board of Directors or advisory committees; Roche Pharma: Consultancy. Alizadeh: Gilead: Consultancy; Roche: Consultancy; Forty Seven: Other: stock; BMS: Research Funding; CARGO Therapeutics: Divested equity in a private or publicly-traded company in the past 24 months; CiberMed: Consultancy, Other: Scientific Co-founder; Foresight: Consultancy, Other: Scientific Co-founder; Pharmacyclics: Consultancy; ADC Therapeutics: Consultancy; Adaptive Biosciences: Consultancy.

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648 Non-Invasive Characterization and Early Detection of Post-Transplant Lymphoproliferative Disorders