Type: Oral
Session: 622. Lymphomas: Translational - Non-Genetic: Demystifying the Complexity of the Lymphoma Tumor Microenvironment and Immune Responses
Hematology Disease Topics & Pathways:
Research, Fundamental Science, Translational Research
Methods: We performed 10X Chromium 5’ scRNA-seq on 11 paired cell suspension samples of diagnostic and relapsed cHL, along with 4 reactive lymph node (RLN) control samples. To enhance representation of immune and lineage-related genes for accurate description of TME biology, we performed hybrid-capture sequencing (CapID+) on the same scRNA-seq libraries. Additionally, we validated our results at the protein level in intact tissue using immunohistochemistry (IHC) and IMC on a tissue microarray (TMA) representing 71 independent diagnostic/relapse sample pairs. For correlative analyses, patients were classified as early-relapse if disease progressed within 12 months after initial diagnosis or if their disease was refractory to first-line ABVD/ABVD-like treatment.
Results: Across all diagnostic/relapsed cHL and RLN samples, we obtained a total of 49,843 transcriptomes after quality filtering, of which 21,718 (HL:20038; RLN:1680) were found to be expressing canonical B cell markers. Unsupervised clustering on B cells identified 10 subclusters including 1 naïve-B cell cluster, 1 memory B-cell cluster, 2 activated B-cell clusters, 2 atypical B-cell clusters, 1 cycling B-cell cluster, 1 germinal center B-cell (GCB) cluster, and 1 plasma cell cluster. The naïve B-cell cluster, C1, showed statistically significant enrichment (P < 0.05) in early-relapse samples compared to either diagnostic or late-relapse samples. In contrast, the memory B-cell cluster, C2, showed an opposite enrichment where early-relapse samples showed a statistically significantly decreased proportion compared to either diagnostic or late-relapse samples (P < 0.05). C1 was characterized by high expression of migration markers (CCR6+, CXCR5+) and regulatory markers (LGASL9+) along with naïve B-cell markers (IGHD+, IGHM+, IL4R+, SELL+). C2 demonstrated high expression of regulatory markers (ITGAM+, IL2RA+) as well as memory B-cell markers (IGHA2+, IGHG1+ CD27+ TNFRSF13B+). We validated the enrichment of unswitched naïve B cells in early-relapse samples using IgD IHC compared to diagnostic (P<0.05) and late-relapse samples (P < 0.05).
Using in silico cell-to-cell interaction analysis (CellChat), the naïve B-cell cluster, C1, was predicted to interact with CD4+ LAG3+ Tregs uniquely in early-relapse samples through the Galectin-9 – TIM-3 axis (P < 0.05). To validate the cell-cell interaction results from scRNA-seq at the protein level and gain a more comprehensive understanding of spatial relationships of non-malignant B cells, we reanalyzed IMC data published by our group (Aoki et al, JCO 2024). CXCR5 and Galectin-9 positivity was used to define naïve B cells consistent with C1 co-expression patterns by scRNA-seq data. We found that CXCR5+ Galectin-9+ naïve B cells were in close proximity to HRS cells in early-relapse samples compared to diagnostic and late-relapse samples (P<0.05). Additionally, CXCR5+ Galectin-9+ naïve B cells were in closer spatial proximity of all Tregs and TIM-3+ CD4+ T cells in early-relapse samples compared to diagnostic and late-relapse samples.
Conclusion: Our single cell studies of relapsed cHL revealed unique naive and memory B cell populations specific to relapse status. Our cell-cell interaction and spatial analyses highlight future potential for immunotherapeutic targeting of B cell and Treg subsets contributing to immunosuppression in early-relapse cHL.
Disclosures: Chong: AbCellera: Current Employment. Hung: QIAGEN: Current Employment. Merchant: BMS: Speakers Bureau; Oncovalent: Consultancy, Research Funding; Innate Pharma: Research Funding; IMMpact Bio: Research Funding; Abbvie: Consultancy, Speakers Bureau; Genmab: Consultancy, Speakers Bureau; Amgen: Consultancy. Scott: Veracyte: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Genmab: Consultancy, Honoraria; AstraZenenca: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Roche/Genentech: Research Funding; Nanostring: Patents & Royalties: use of gene expresssion to subtype aggressive lymphoma. Savage: Regeneron: Other: DSMC; Seagen: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy; Bristol Myers Squibb: Consultancy, Research Funding. Steidl: AbbVie: Consultancy; Epizyme: Research Funding; Seattle Genetics: Consultancy; EISAI: Consultancy; Trillium Therapeutics Inc: Research Funding; Bristol Myers Squibb: Research Funding; Bayer: Consultancy.