A high-resolution view of intra-tumoral B cell immunity

In this issue of Immunity, Meylan et al., 2022Meylan M. Petitprez F. Becht E. Bougouin A. Pupier G. Calvez A. Giglioli I. Verkarre V. Lacroix G. Verneau J. et al.Tertiary lymphoid structures generate and propagate anti-tumor antibody-producing plasma cells in renal cell cancer.Immunity. 2022; 55: 527-541Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar uses spatial transcriptomics to examine B cell immunity within intratumoral tertiary lymphoid structures (TLSs). They find that B cells expand and mature into plasma cells (PCs) within the TLS, migrate along fibroblastic tracks to tumor beds, and produce IgG antibodies that target cancer cells. In this issue of Immunity, Meylan et al., 2022Meylan M. Petitprez F. Becht E. Bougouin A. Pupier G. Calvez A. Giglioli I. Verkarre V. Lacroix G. Verneau J. et al.Tertiary lymphoid structures generate and propagate anti-tumor antibody-producing plasma cells in renal cell cancer.Immunity. 2022; 55: 527-541Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar uses spatial transcriptomics to examine B cell immunity within intratumoral tertiary lymphoid structures (TLSs). They find that B cells expand and mature into plasma cells (PCs) within the TLS, migrate along fibroblastic tracks to tumor beds, and produce IgG antibodies that target cancer cells. Decades ago, anti-HER2 antibodies generated by cancer patients were detected in the serum of breast cancer patients (Disis et al., 1997Disis M.L. Pupa S.M. Gralow J.R. Dittadi R. Menard S. Cheever M.A. High-titer HER-2/neu protein-specific antibody can be detected in patients with early-stage breast cancer.J. Clin. Oncol. 1997; 15: 3363-3367Crossref PubMed Scopus (307) Google Scholar), raising the tantalizing possibility that B cell immunity might be harnessed to treat cancer. Recent large-scale genomic analyses revealed that B cell clonal expansion, somatic hypermutation, and isotype switch are common both in solid tumors (Hu et al., 2019Hu X. Zhang J. Wang J. Fu J. Li T. Zheng X. Wang B. Gu S. Jiang P. Fan J. et al.Landscape of B cell immunity and related immune evasion in human cancers.Nat. Genet. 2019; 51: 560-567Crossref PubMed Scopus (90) Google Scholar) and in leukemia (Zhang et al., 2019Zhang J. Hu X. Wang J. Sahu A.D. Cohen D. Song L. Ouyang Z. Fan J. Wang B. Fu J. et al.Immune receptor repertoires in pediatric and adult acute myeloid leukemia.Genome Med. 2019; 11: 73Crossref PubMed Scopus (28) Google Scholar). Melanoma (Bolotin et al., 2017Bolotin D.A. Poslavsky S. Davydov A.N. Frenkel F.E. Fanchi L. Zolotareva O.I. Hemmers S. Putintseva E.V. Obraztsova A.S. Shugay M. et al.Antigen receptor repertoire profiling from RNA-seq data.Nat. Biotechnol. 2017; 35: 908-911Crossref PubMed Scopus (160) Google Scholar) and leukemia (Zhang et al., 2019Zhang J. Hu X. Wang J. Sahu A.D. Cohen D. Song L. Ouyang Z. Fan J. Wang B. Fu J. et al.Immune receptor repertoires in pediatric and adult acute myeloid leukemia.Genome Med. 2019; 11: 73Crossref PubMed Scopus (28) Google Scholar) patients bearing tumors enriched in IgG antibodies and depleted with IgA antibodies exhibit improved clinical outcomes. Intratumoral tertiary lymphoid structures (TLSs), which are enriched in B cells, are associated with better responses to immune checkpoint blockade (ICB) in multiple cancer types (Cabrita et al., 2020Cabrita R. Lauss M. Sanna A. Donia M. Skaarup Larsen M. Mitra S. Johansson I. Phung B. Harbst K. Vallon-Christersson J. et al.Tertiary lymphoid structures improve immunotherapy and survival in melanoma.Nature. 2020; 577: 561-565Crossref PubMed Scopus (888) Google Scholar; Helmink et al., 2020Helmink B.A. Reddy S.M. Gao J. Zhang S. Basar R. Thakur R. Yizhak K. Sade-Feldman M. Blando J. Han G. et al.B cells and tertiary lymphoid structures promote immunotherapy response.Nature. 2020; 577: 549-555Crossref PubMed Scopus (1062) Google Scholar; Petitprez et al., 2020Petitprez F. de Reyniès A. Keung E.Z. Chen T.W.-W. Sun C.-M. Calderaro J. Jeng Y.-M. Hsiao L.P. Lacroix L. Bougoüin A. et al.B cells are associated with survival and immunotherapy response in sarcoma.Nature. 2020; 577: 556-560Crossref PubMed Scopus (880) Google Scholar; Gao et al., 2020Gao Y. Nihira N.T. Bu X. Chu C. Zhang J. Kolodziejczyk A. Fan Y. Chan N.T. Ma L. Liu J. et al.Acetylation-dependent regulation of PD-L1 nuclear translocation dictates the efficacy of anti-PD-1 immunotherapy.Nat. Cell Biol. 2020; 22: 1064-1075Crossref PubMed Scopus (133) Google Scholar). However, the role of TLSs in driving B cell differentiation and antibody production, as well as how this influences the response to ICB, are not fully understood. In this issue of Immunity, Meylan et al., 2022Meylan M. Petitprez F. Becht E. Bougouin A. Pupier G. Calvez A. Giglioli I. Verkarre V. Lacroix G. Verneau J. et al.Tertiary lymphoid structures generate and propagate anti-tumor antibody-producing plasma cells in renal cell cancer.Immunity. 2022; 55: 527-541Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar aimed to answer these questions using spatial transcriptomics and immunochemistry to characterize TLS composition and B cell maturation in renal cell carcinoma (ccRCC) tumor samples. Meylan et al. first collected fresh-frozen and fixed ccRCC tumors and annotated TLS presence using immunochemistry. They then quantified the spatial expression in a subset of 24 tumors using the 10X Genomics Visium technology. Each Visium slide contains 5,000 spots, each with a unique barcode to encode the spatial information of up to 10 cells. RNA sequencing of the barcoded transcripts can recover both the spatial and gene expression information within each spot, and the cells within each spot can be computationally inferred based on expression signatures. In TLS+ ccRCC tumors, the authors observed hotspots of co-localized expression signatures of B cells, T cells, and fibroblasts in the tumor microenvironment (Figure 1). Although the expression of IGHM, encoding Ig heavy-chain Mu, was exclusively seen in the TLSs, the expression of IGHG1 and IGHA1 was observed not only inside the germinal center of the TLSs but also in other regions in the tumors. To examine somatic hypermutations and affinity maturation within the TLS, Meylan et al. obtained the CDR3 sequences of the B cell receptors (BCRs). This allowed the authors to infer clonal expansion inside TLSs, which revealed that B cells outside of TLSs harbor more somatic hypermutations than those within TLSs. Together, these data suggest that in TLS+ tumors, B cells mature inside TLSs through clonal expansion, somatic hypermutation, and isotype switch to IgG and IgA antibody-producing PCs, and then disseminate to various areas of the tumor beds. Besides the Visium technology to evaluate spatial RNA expression, Meylan et al. also used immunohistochemistry and multiplex immunofluorescence labeling to evaluate spatial protein expression in the tumors. They used MZB1 as an RNA marker for PCs and COL1A1 and CXCL12 as RNA markers for fibroblasts. They also used MUM1 as a protein marker for PCs and COL1 and CXCL12 as the protein markers for fibroblasts. PCs were detected at high levels both inside TLSs but also in tumor beds, and co-expression of PC markers and fibroblast markers was observed both within the TLSs and outside. TLS presence was strongly associated with the density of MUM1+IgG+ cells in the tumors. In tumor beds surrounded by MUM1+IgG+ fibroblastic tracks, the authors detected co-localization of apoptotic cancer cells with IgG antibodies, but not with IgA antibodies. Interestingly, tumors with IgG-stained apoptotic cancer cells exhibited higher macrophage infiltration. These data suggest that antibody-producing PCs, once matured in TLSs, are dispatched to tumor beds along fibroblastic tracks. IgG antibodies produced by the PCs bind to cancer cells to kill directly or indirectly through effector macrophages (Figure 1). Finally, the authors evaluated 51 ccRCC tumors that were later treated with either nivolumab + ipilimumab or nivolumab alone. Tumors with higher IgG staining had significantly better progression-free survival and a trend for higher objective response to ICB. Existing ICB approaches seek to activate T cells in tumors, but B cells and TLS seem to be better predictors of treatment response than T cell signatures (Cabrita et al., 2020Cabrita R. Lauss M. Sanna A. Donia M. Skaarup Larsen M. Mitra S. Johansson I. Phung B. Harbst K. Vallon-Christersson J. et al.Tertiary lymphoid structures improve immunotherapy and survival in melanoma.Nature. 2020; 577: 561-565Crossref PubMed Scopus (888) Google Scholar; Helmink et al., 2020Helmink B.A. Reddy S.M. Gao J. Zhang S. Basar R. Thakur R. Yizhak K. Sade-Feldman M. Blando J. Han G. et al.B cells and tertiary lymphoid structures promote immunotherapy response.Nature. 2020; 577: 549-555Crossref PubMed Scopus (1062) Google Scholar; Petitprez et al., 2020Petitprez F. de Reyniès A. Keung E.Z. Chen T.W.-W. Sun C.-M. Calderaro J. Jeng Y.-M. Hsiao L.P. Lacroix L. Bougoüin A. et al.B cells are associated with survival and immunotherapy response in sarcoma.Nature. 2020; 577: 556-560Crossref PubMed Scopus (880) Google Scholar; Gao et al., 2020Gao Y. Nihira N.T. Bu X. Chu C. Zhang J. Kolodziejczyk A. Fan Y. Chan N.T. Ma L. Liu J. et al.Acetylation-dependent regulation of PD-L1 nuclear translocation dictates the efficacy of anti-PD-1 immunotherapy.Nat. Cell Biol. 2020; 22: 1064-1075Crossref PubMed Scopus (133) Google Scholar). Meylan et al., 2022Meylan M. Petitprez F. Becht E. Bougouin A. Pupier G. Calvez A. Giglioli I. Verkarre V. Lacroix G. Verneau J. et al.Tertiary lymphoid structures generate and propagate anti-tumor antibody-producing plasma cells in renal cell cancer.Immunity. 2022; 55: 527-541Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar elegantly demonstrates the power of combining novel genomic technology and computational analyses to provide important spatial insights into the tumor immune microenvironment. This study revealed that B cells matured in TLSs have antitumor activities before ICB treatment and affirmed that patients with more IgG tumoral staining have better responses to ICB and longer survival. The trajectory of B cell maturation, migration, and tumor killing observed in tumors also supports the important roles played by TLSs, fibroblasts, and macrophages in tumor humoral response. The interesting observations from Meylan et al. also raise many intriguing questions for future explorations. For example, the observation of TLS+ versus TLS− ccRCC tumors suggests the need to understand factors, such as antigen presentation, T helper cells, or cytokine signals, that can influence the formation and maintenance of TLSs. The observation that TLS-matured PCs produce IgA antibodies as well as IgG antibodies suggests that cancer cells might secrete cytokines to induce isotype switch in PCs to produce IgA instead of IgG antibodies, thus suppressing humoral immunity in tumors. The observation that antibody-producing PCs outside the TLS co-localize with fibroblasts also raises the question of whether CXCL12 is a driver or whether there are other protein-protein interactions that direct plasma cell (PC) migration along fibroblastic tracks. In addition, it is unclear whether additional somatic hypermutation and isotype switching occur outside the TLS as PCs migrate along fibroblastic tracks or are exposed to tumor antigens in the tumor beds. It is also unclear whether and how much lymph node-matured PCs, in addition to TLS-matured PCs, migrate to tumor beds to exert anti-tumor effects. The observed enrichment of macrophages but not natural killer cells near IgG-stained apoptotic cancer cells also begs the question of whether this is specific to ccRCC or is a more general phenomenon in other cancer types. Macrophages have ample expression of PD-L1, which can be targeted by ICB. It would be interesting to evaluate whether ICB treatment changes the behavior of PC migration in the tumors and whether intraturmal TLS-matured PCs further diffuse to the circulatory system. Finally, the wide existence of IgG-stained cancer cells in TLS+ tumors indicates that some IgG antibodies are specifically recognizing malignant cells, which often present mutated or dysregulated proteins on the cell surface. The exact pairing of tumor antigens and tumor-recognizing antibodies awaits to be elucidated. In summary, using cutting-edge genomics and computational approaches, Meylan et al., 2022Meylan M. Petitprez F. Becht E. Bougouin A. Pupier G. Calvez A. Giglioli I. Verkarre V. Lacroix G. Verneau J. et al.Tertiary lymphoid structures generate and propagate anti-tumor antibody-producing plasma cells in renal cell cancer.Immunity. 2022; 55: 527-541Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar characterized the microenvironments of ccRCC tumors in unprecedented spatial details. The study provides deep insights into B cell maturation in TLSs, PC migration along fibroblastic tracks, and IgG antibody function in tumor killing. Although it is still challenging to predict antibody-antigen binding using 3D structure-based artificial intelligence (AI) methods, antigen-antibody associations might be inferred from the large volume of naturally occurring antibodies in human tumors (Hu et al., 2019Hu X. Zhang J. Wang J. Fu J. Li T. Zheng X. Wang B. Gu S. Jiang P. Fan J. et al.Landscape of B cell immunity and related immune evasion in human cancers.Nat. Genet. 2019; 51: 560-567Crossref PubMed Scopus (90) Google Scholar). However, depending on T helper cells, cytokine signals, antibody isotypes, and specificities, antibodies produced by PCs might have pro-tumor or anti-tumor responses (Shalapour and Karin, 2021Shalapour S. Karin M. The neglected brothers come of age: B cells and cancer.Semin. Immunol. 2021; 52: 101479https://doi.org/10.1016/j.smim.2021.101479Crossref PubMed Scopus (20) Google Scholar). Therefore, better AI modeling of antigen-antibody pairs in human tumors and better understanding of their precise immune functions are needed to bring paradigm shifts to immuno-oncology antibody drug discovery and unleash natural humoral responses to fight cancer. X.S.L. is a board member and shareholder of GV20 Oncotherapy and the CEO of its subsidiary, GV20 Therapeutics. X.H. is a shareholder of GV20 Oncotherapy and the Chief Information Officer of its subsidiary, GV20 Therapeutics. Tertiary lymphoid structures generate and propagate anti-tumor antibody-producing plasma cells in renal cell cancerMeylan et al.ImmunityFebruary 28, 2022In BriefMeylan et al. show that tertiary lymphoid structures found in tumors are sites of generation of fully mature B cell immunity. Plasma cells disseminate into tumor beds, producing antibodies that bind to tumor cells and initiate their apoptosis, providing a mechanism to support cancer immunotherapies that modulate the tumor microenvironment. Full-Text PDF Open Archive