Circulating Tumor DNA-Based Genotyping and Monitoring for Predicting Disease Relapses of Patients with Peripheral T-Cell Lymphomas.

PURPOSE: Plasma circulating tumor DNA (ctDNA) could reflect the genetic alterations present in tumor tissues. However, there is little information about the clinical relevance of cell-free DNA genotyping in peripheral T-cell lymphoma (PTCL). MATERIALS AND METHODS: After targeted sequencing plasma cell-free DNA of patients with various subtypes of PTCL (n=94), we analyzed the mutation profiles of plasma ctDNA samples and their predictive value of dynamic ctDNA monitoring for treatment outcomes. RESULTS: Plasma ctDNA mutations were detected in 53 patients (56%, 53/94), and the detection rate of somatic mutations was highest in angioimmunoblastic T-cell lymphoma (24/31, 77%) and PTCL, not otherwise specified (18/29, 62.1%). Somatic mutations were detected in 51 of 66 genes that were sequenced, including the following top 10 ranked genes: RHOA, CREBBP, KMT2D, TP53, IDH2, ALK, MEF2B, SOCS1, CARD11, and KRAS. In the longitudinal assessment of ctDNA mutation, the difference in ctDNA mutation volume after treatment showed a significant correlation with disease relapse or progression. Thus, a ≥ 1.5-log decrease in genome equivalent (GE) between baseline and the end of treatment showed a significant association with better survival outcomes than a < 1.5-log decrease in GE. CONCLUSION: Our results suggest the clinical relevance of plasma ctDNA analysis in patients with PTCL. However, our findings should be validated by a subsequent study with a larger study population and using a broader gene panel.

Exosomal and Soluble Programed Death-Ligand 1 (PD-L1) Predicts Responses to Pembrolizumab in Patients with Extranodal NK/T-Cell Lymphoma.

Soluble and exosomal programed death-ligand 1 (PD-L1) can be upregulated in extranodal natural killer/T-cell lymphoma (ENKTL). However, its clinical role in predicting outcomes after pembrolizumab treatment has yet to be studied in ENKTL patients. We investigated the association between pre-treatment soluble and exosomal PD-L1 and outcomes in ENKTL patients who received pembrolizumab as a salvage treatment. The production of soluble and exosomal PD-L1 was analyzed in vitro using an etoposide-resistant ENKTL cell line. Serum levels of soluble and exosomal PD-L1 were measured in patients with relapsed or refractory ENKTL prior to treatment with pembrolizumab. Relapsed or refractory ENKTL patients who received pembrolizumab as a salvage therapy between May 2017 and March 2021 were analyzed at our institute. Soluble and exosomal PD-L1 was significantly higher in serum samples of relapsed or refractory ENKTL patients compared with healthy controls, which is consistent with increased production of soluble and exosomal PD-L1 in an etoposide-resistant ENKTL cell line (SNK6R), which was found to show increased expression of soluble and exosomal PD-L1. Serum-soluble PD-L1 levels were significantly correlated with exosomal PD-L1, and were significantly lower in responders to pembrolizumab compared with non-responders. Longitudinal analysis after pembrolizumab also revealed a relationship between PD-L1 levels and responses. Treatment outcomes and overall survival after pembrolizumab were significantly better in patients with low soluble and exosomal PD-L1. In conclusion, soluble and exosomal PD-L1 can predict responses to pembrolizumab in ENKTL patients, making it a useful pre-treatment biomarker for ENKTL patients receiving pembrolizumab.

Clinical relevance of serum-derived exosomal messenger RNA sequencing in patients with non-Hodgkin lymphoma.

Background: The clinical utility of mRNA cargo in exosomes is unclear, although exosomes have potential as non-invasive biomarkers. This study aimed to investigate the feasibility of exosomal mRNA sequencing for monitoring disease status and predicting outcomes in non-Hodgkin lymphoma (NHL) patients. Methods: Exosomes were isolated from archived serum samples of 33 patients with NHL who were registered into our prospective cohort: diffuse large B-cell lymphoma (DLBCL, n = 17), intravascular B-cell lymphoma (IVL, n = 1), primary mediastinal large B-cell lymphoma (PMBL, n = 4), follicular lymphoma (FL, n = 3), mantle cell lymphoma (MCL, n = 3), and extranodal NK/T-cell lymphoma (ENKTL, n = 5). Exosomal mRNA sequencing was performed, and its concordance with clinical course was analyzed and compared with those of circulating tumor DNA (ctDNA) mutations. Results: Exosomal mRNA sequencing was performed successfully in 26 cases (79%, 26/33), whereas the remaining seven cases were not completed due to their small amount of RNA. The exosomal mRNA sequencing of DLBCL showed gene expression profiles consistent with activated B-cell-like and germinal center type. The longitudinal assessment of exosomal mRNA sequencing results in accordance with the clinical course showed that the post-treatment changes of exosomal mRNA expression were more consistent with treatment outcome than were those of ctDNA mutations. In particular, the exosomal mRNA expression of genes such as BCL2 and BCL6 was increased at the time of disease progression in DLBCL and FL patients. Conclusions: This study demonstrated the feasibility of exosomal mRNA expression profiles as a biomarker for NHL patients. Our results might provide the rationale for studies to explore the potential of exosomal mRNA as a biomarker in NHL patients.