Recent Advances in Adult Post-Transplant Lymphoproliferative Disorder

STAT3 Signaling Pathway in Health and Disease

Signal transducer and activator of transcription 3 (STAT3) is a critical transcription factor involved in multiple physiological and pathological processes. While STAT3 plays an essential role in homeostasis, its persistent activation has been implicated in the pathogenesis of various diseases, particularly cancer, bone-related diseases, autoimmune disorders, inflammatory diseases, cardiovascular diseases, and neurodegenerative conditions. The interleukin-6/Janus kinase (JAK)/STAT3 signaling axis is central to STAT3 activation, influencing tumor microenvironment remodeling, angiogenesis, immune evasion, and therapy resistance. Despite extensive research, the precise mechanisms underlying dysregulated STAT3 signaling in disease progression remain incompletely understood, and no United States Food and Drug Administration (USFDA)-approved direct STAT3 inhibitors currently exist. This review provides a comprehensive evaluation of STAT3's role in health and disease, emphasizing its involvement in cancer stem cell maintenance, metastasis, inflammation, and drug resistance. We systematically discuss therapeutic strategies, including JAK inhibitors (tofacitinib, ruxolitinib), Src Homology 2 domain inhibitors (S3I-201, STATTIC), antisense oligonucleotides (AZD9150), and nanomedicine-based drug delivery systems, which enhance specificity and bioavailability while reducing toxicity. By integrating molecular mechanisms, disease pathology, and emerging therapeutic interventions, this review fills a critical knowledge gap in STAT3-targeted therapy. Our insights into STAT3 signaling crosstalk, epigenetic regulation, and resistance mechanisms offer a foundation for developing next-generation STAT3 inhibitors with greater clinical efficacy and translational potential.

Navigating Epstein-Barr Virus (EBV) and Post-Transplant Lymphoproliferative Disorder (PTLD) in Pediatric Liver Transplantation: Current Knowledge and Strategies for Treatment and Surveillance

Epstein-Barr virus (EBV) is strongly associated with the development of post-transplant lymphoproliferative disorder (PTLD) in pediatric liver transplant recipients. PTLD is one of the most common malignancies following liver transplantation and is associated with significant morbidity and mortality. Factors such as EBV-serostatus mismatch and prolonged or high levels of immunosuppression impact a patient's risk of developing PTLD. While pre-transplant EBV serological screening and post-transplant monitoring of EBV-DNA levels are strongly recommended, universal guidelines for its prevention and management are lacking. Due to a lack of robust prospective studies, current clinical practices vary widely. The treatment of PTLD typically involves reducing immunosuppression and using targeted therapies such as rituximab, or chemotherapy for refractory cases. This review aims to address our current understanding of EBV's relationship with PTLD, evaluate the available treatment modalities, and highlight evolving strategies for using EBV as a biomarker for PTLD screening and prevention.

Post-Transplant Lymphoproliferative Disorder at the Porta Hepatis Causing Hepatic Artery Stenosis and Cholestasis

BACKGROUND Post-transplant lymphoproliferative disorder (PTLD) encompasses a group of disorders ranging from hyperplastic to malignant lymphoid proliferations in the post-transplant period owing to immunosuppression, often in the setting of EBV transformation. PTLD is a rare complication of immunosuppression that, like lymphomas, can have a variable presentation based on disease localization. We report a case of PTLD mass effect at the porta hepatis for the first time in the literature, resulting in hepatic artery stenosis (HAS) and common hepatic duct obstruction. CASE REPORT A 54-year-old woman presented with cholestasis 4 months after receiving a deceased donor liver transplant. MRCP revealed a mass at the porta hepatis causing biliary compression, which resolved with subsequent biliary stenting. The woman presented again 3 weeks later with a similar presentation. CT revealed that the mass had enlarged, causing HAS, which resolved with subsequent hepatic artery stenting. The biopsy revealed PTLD, and the patient was successfully managed with rituximab and a reduction of her immunosuppressive regimen. CONCLUSIONS This case report describes a rare occurrence of PTLD, which particularly impacting the porta hepatis, resulting in HAS and compression of the bile duct. PTLD should be considered in the differential diagnosis for obstructive jaundice and hepatic artery compression, even in the early post-transplant months, when these symptoms are often attributed to surgical factors.

Utility of 18F-FDG PET/CT metabolic parameters on post-transplant lymphoproliferative disorder diagnosis

OBJECTIVE

Using 18F-FDG PET/CT metabolic parameters to differentiate post-transplant lymphoproliferative disorder (PTLD) and reactive lymphoid hyperplasia (RLH), and PTLD subtypes.

METHODS

18F-FDG PET/CT and clinical data from 63 PTLD cases and 19 RLH cases were retrospectively collected. According to the 2017 WHO classification, PTLD was categorized into four subtypes: nondestructive (ND-PTLD), polymorphic (P-PTLD), monomorphic (M-PTLD), and classic Hodgkin. Metabolic parameters included maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and at different thresholds of SUVmax (2.5 and 41%), as well as gross tumor volume (GTV) was also collected. Nonparametric test and receiver operating characteristic (ROC) curves were used for statistics.

RESULTS

There were 42 ND-PTLD patients, 7 P-PTLD patients, and 14 M-PTLD patients. Ki-67 was significantly correlated with all metabolic parameters (P all < 0.01). SUVmean, SUVmax, MTV, TLG and GTV were all highest in M-PTLD, followed by P-PTLD, ND-PTLD, and RLH. ROC curves showed 18F-FDG PET/CT metabolic parameters all had moderate diagnostic efficacy in differentiating between PTLD and RLH, the area under the curves (AUC) range from 0.682 to 0.747. Diagnostic efficacy for P-PTLD + M-PTLD showed excellent performance (AUC for RLH + ND-PTLD vs P-PTLD + M-PTLD was 0.848 for SUVmax, 0.846 for SUVmean41%, 0.834 for SUVmean2.5, and 0.819 for GTV). For MTV41%, TLG 41%, MTV2.5, TLG2.5, the AUC was 0.676, 0.761, 0.761, 0.787, respectively.

CONCLUSION

18F-FDG PET/CT metabolic parameters at different thresholds of SUVmax (2.5 and 41%) exhibited comparable diagnostic efficacy for PTLD and its subtypes. All metabolic parameters demonstrated moderate diagnostic efficacy in distinguishing PTLD and RLH. SUVmax, SUVmean41%, SUVmean2.5 and GTV showed excellent performance in diagnosing P-PTLD + M-PTLD.

Recurrent Verruconis gallopava Infection at One Year after Excision of a Solitary Pulmonary Lesion

We herein report a case of recurrent infection caused by Verruconis gallopava, which is known to cause fatal phaeohyphomycosis. A 71-year-old man presented with a fever, and computed tomography revealed right chest wall thickening. Eleven years earlier, he had undergone autologous peripheral blood stem cell transplantation for a hematological malignancy. One year earlier, he had undergone excision of a solitary pulmonary nodule, from which had been detected V. gallopava. On this occasion, right chest wall surgery was performed to investigate the cause of the fever, which led to the diagnosis of recurrent infection. Even if a localized lesion is excised, additional antifungal therapy should be performed.

Post-transplant lymphoproliferative disorder in pediatric liver transplant recipients: Experience from a South African transplant center

INTRODUCTION

Post-transplant lymphoproliferative disorder (PTLD) is a clinically heterogeneous potentially fatal complication of pediatric liver transplantation (PLT). We determined the prevalence, complications, and associated factors for PTLD in PLT recipients from Wits Donald Gordon Medical Centre, South Africa from January 2012 to August 2019.

METHODS

We performed a retrospective record review of 150 PLT recipients.

RESULTS

Histologically proven PTLD occurred in 17/150 PLT recipients (11.3%). Children with PTLD were significantly younger at transplant (17.9 vs. 32.7 months, p = 0.001) with a significantly higher prevalence of obstructive etiology (17/17 vs. 81/133, p = 0.001). Fifteen (88.2%) children with PTLD were Epstein-Barr virus (EBV) seronegative at transplant. High post-transplant EBV viral load at a threshold value of 4.8 log10 DNA copies/mL (sensitivity: 80.0% [95% confidence interval {CI}, 46.7%-100.0%]; specificity: 73.1% [95% CI 42.3%-93.3%; area under the curve {AUC} 75.8%]) and low post-transplant albumin levels at a threshold value of 21.5 g/L (sensitivity: 70.6% [95% CI, 41.2%-94.1%]; specificity: 85.7% [95% CI, 60.4%-94.5%; {AUC} 74.8%]) were associated with PTLD. The prevalence of cytomegalovirus (CMV) disease was significantly higher in children who developed PTLD versus non-PTLD (12/17 vs. 18/133; p < 0.001). CMV disease and the combination of post-transplant high EBV viral load and low albumin were independently associated with an increased risk of developing PTLD. Four (23.5%) children with PTLD died, however, survival was equivalent to non-PTLD PLT (p = 0.580).

CONCLUSION

The prevalence of PTLD in our cohort mirrors international cohorts, with mortality similar to non-PTLD PLT recipients.

Immune deficiency/dysregulation -associated lymphoproliferative disorders. Revised classification and management

Significant advances in the field of lymphoma have resulted in two recent classification proposals, the International Consensus Classification (ICC) and the 5th edition WHO. A few entities are categorized differently in the ICC compared to the WHO. Nowhere is this more apparent than the immunodeficiency lymphoproliferative disorders. The three previous versions of the WHO classification (3rd, 4th and revised 4th editions) and the ICC focused on four clinical settings in which these lesions arise for primary categorization. In contrast the 2023 WHO 5th edition includes pathologic characteristics including morphology and viral status, in addition to clinical setting, as important information for lesion classification. In addition, the 2023 WHO recognizes a broader number of clinical scenarios in which these lesions arise, including not only traditional types of immune deficiency but also immune dysregulation. With this classification it is hoped that new treatment strategies will be developed leading to better patient outcomes.

The role of 18F-FDG PET/CT metabolic parameters in the differential diagnosis of post-transplant lymphoproliferative disorder after pediatric liver transplantation

Background

Post-transplant lymphoproliferative disorder (PTLD) is a significant complication after liver transplantation. Research on the diagnostic value of the Fluorine-18 fluorodeoxyglucose positron emission tomography/computerized tomography (18F-FDG PET/CT) metabolic parameters of PTLD in pediatric liver transplantation (pLT) recipients is limited. This study sought to evaluate the diagnostic efficacy of 18F-FDG PET/CT in differentiating between PTLD and non-PTLD lymphadenopathy in pLT recipients.

Methods

This retrospective study collected the 18F-FDG PET/CT scans with clinical and pathological information of all consecutive children who were clinically suspected of PTLD from November 2016 to September 2022 at the Beijing Friendship Hospital. The 18F-FDG PET/CT metabolic parameters of the two groups were analyzed. We then established a diagnostic model composed of the clinical characteristics and metabolic parameters.

Results

In total, 57 eligible patients were enrolled in this study, of whom 40 had PTLD and 17 had non-PTLD lymphadenopathy. Of the metabolic parameters examined in this study, total lesion glycolysis (TLG) had the highest area under the curve (AUC) value [0.757, 95% confidence interval (CI): 0.632-0.883, P=0.002]. The AUCs of the other metabolic parameters were all less than the AUC of TLG, including the maximum standardized uptake value (SUVmax) (AUC: 0.725, 95% CI: 0.597-0.853, P=0.008), mean standardized uptake value (SUVmean) (AUC: 0.701, 95% CI: 0.568-0.834, P=0.017), metabolic tumor volume total (MTVtotal) (AUC: 0.688, 95% CI: 0.549-0.827, P=0.040), TLG total (AUC: 0.674, 95% CI: 0.536-0.812, P=0.026). The diagnostic model, which was composed of clinical characteristics (digestive symptoms), the SUVmax, TLG, and the MTVtotal, showed excellent performance in the differential diagnosis (sensitivity: 0.675, 95% CI: 0.508-0.809; specificity: 0.941, 95% CI: 0.692-0.997; positive predictive value: 0.964, 95% CI: 0.798-0.998; and negative predictive value: 0.552, 95% CI: 0.360-0.730).

Conclusions

The 18F-FDG PET/CT metabolic parameters can be used to distinguishing between PTLD and non-PTLD lymphadenopathy in pLT recipients.

Genomic profiling of post-transplant lymphoproliferative disorders using cell-free DNA

Diagnosing post-transplant lymphoproliferative disorder (PTLD) is challenging and often requires invasive procedures. Analyses of cell-free DNA (cfDNA) isolated from plasma is minimally invasive and highly effective for genomic profiling of tumors. We studied the feasibility of using cfDNA to profile PTLD and explore its potential to serve as a screening tool. We included seventeen patients with monomorphic PTLD after solid organ transplantation in this multi-center observational cohort study. We used low-coverage whole genome sequencing (lcWGS) to detect copy number variations (CNVs) and targeted next-generation sequencing (NGS) to identify Epstein-Barr virus (EBV) DNA load and somatic single nucleotide variants (SNVs) in cfDNA from plasma. Seven out of seventeen (41%) patients had EBV-positive tumors, and 13/17 (76%) had stage IV disease. Nine out of seventeen (56%) patients showed CNVs in cfDNA, with more CNVs in EBV-negative cases. Recurrent gains were detected for 3q, 11q, and 18q. Recurrent losses were observed at 6q. The fraction of EBV reads in cfDNA from EBV-positive patients was 3-log higher compared to controls and EBV-negative patients. 289 SNVs were identified, with a median of 19 per sample. SNV burden correlated significantly with lactate dehydrogenase levels. Similar SNV burdens were observed in EBV-negative and EBV-positive PTLD. The most commonly mutated genes were TP53 and KMT2D (41%), followed by SPEN, TET2 (35%), and ARID1A, IGLL5, and PIM1 (29%), indicating DNA damage response, epigenetic regulation, and B-cell signaling/NFkB pathways as drivers of PTLD. Overall, CNVs were more prevalent in EBV-negative lymphoma, while no difference was observed in the number of SNVs. Our data indicated the potential of analyzing cfDNA as a tool for PTLD screening and response monitoring.

Important Considerations in the Diagnosis and Management of Post-transplant Lymphoproliferative Disorder

PURPOSE OF REVIEW

A relative lack of molecular and clinical studies compared to other lymphoid cancers has historically made it difficult to determine optimal management approaches in post-transplant lymphoproliferative disorder (PTLD). We sought to better define the "state of the science" in PTLD by examining recent advances in risk assessment, genomic profiling, and trials of PTLD-directed therapy.

RECENT FINDINGS

Several major clinical trials highlight risk-stratified sequential therapy incorporating rituximab with or without chemotherapy as a rational treatment strategy in patients with CD20+ PTLD who do not respond to reduction of immunosuppression alone. Epstein Barr virus (EBV)-targeted cytotoxic lymphocytes are a promising approach in patients with relapsed/refractory EBV+ PTLD, but dedicated clinical trials should determine how autologous chimeric antigen receptor T cell therapy (CAR-T) may be safely administered to PTLD patients. Sequencing studies underscore the important effect of EBV infection on PTLD pathogenesis, but comprehensive genomic and tumor microenvironment profiling are needed to identify biomarkers that predict response to treatment in this clinically heterogeneous disease.