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B cell depletion via anti-CD20 antibodies is a highly effective treatment for multiple sclerosis (MS). However, little is known about the maturation/activation stage of the returning B cell population after treatment cessation and the wider effects on other immune cells. In the present study, 15 relapsing-remitting MS patients receiving 1,000 mg of rituximab were included. B, T, and myeloid cells were analyzed before anti-CD20 administration and in different time intervals thereafter over a period of 24 mo. In comparison to the phenotype before anti-CD20 treatment, the reappearing B cell pool revealed a less mature and more activated phenotype: 1) reappearing B cells were significantly enriched in transitional (before: 10.1 ± 1.9%, after: 58.8 ± 5.2%) and mature naive phenotypes (before: 45.5 ± 3.1%, after: 25.1 ± 3.5%); 2) the frequency of memory B cells was reduced (before: 36.7 ± 3.1%, after: 8.9 ± 1.7%); and 3) reappearing B cells showed an enhanced expression of activation markers CD25 (before: 2.1 ± 0.4%, after: 9.3 ± 2.1%) and CD69 (before: 5.9 ± 1.0%, after: 21.4 ± 3.0%), and expressed significantly higher levels of costimulatory CD40 and CD86. T cells showed 1) a persistent increase in naive (CD4⁺: before: 11.8 ± 1.3%, after: 18.4 ± 3.4%; CD8⁺: before: 12.5 ± 1.4%, after: 16.5 ± 2.3%) and 2) a decrease in terminally differentiated subsets (CD4⁺: before: 47.3 ± 3.2%, after: 34.4 ± 3.7%; CD8⁺: before: 53.7 ± 2.1%, after: 49.1 ± 2.7%).

BackgroundClinical success with chimeric antigen receptor (CAR)- based immunotherapy for leukemia has been accompanied by the associated finding that antigen-escape variants of the disease are responsible for relapse. To target hematologic malignancies with a chimeric antigen receptor (CAR) that targets two antigens with a single vector, and thus potentially lessen the chance of leukemic escape mutations, a tandem-CAR approach was investigated.MethodsAntigen binding domains from the FMC63 (anti-CD19) and Leu16 (anti-CD20) antibodies were linked in differing configurations to transmembrane and T cell signaling domains to create tandem-CARs. Expression on the surface of primary human T cells was induced by transduction with a single lentiviral vector (LV) encoding the tandem-CAR. Tandem-CARs were compared to single antigen targeting CARs in vitro and in vivo, and to an admixture of transduced cells expressing each CAR in vivo in immunodeficient (NSG) disease-bearing mice.ResultsTandem constructs efficient killed the Raji leukemia cell line both in vitro and in vivo. Tandem CARs generated less cytokine than the CD20 CAR, but similar to CD19 CARs, on their own. In co-culture experiments at low effector to target ratios with both single- and tandem- CAR-T cells, a rapid down-modulation of full-length CD19 expression was seen on leukemia targets. There also was a partial down-modulation of CD22, and to a lesser degree, of CD20. Our data also highlight the extreme sensitivity of the NALM-6 cell line to general lymphocyte-mediated cytotoxicity. While single and tandem constructs were effective in vivo in a standard setting, in a high-disease burden setting, the tandem CAR proved both effective and less toxic than an admixture of transduced T cell populations expressing single CARs.ConclusionTandem CARs are equally effective in standard disease models to single antigen specificity CARs, and may be both more effective and less toxic in a higher disease burden setting. This may be due to optimized cell killing with more moderate cytokine production. The rapid co-modulation of CD19, CD20, and CD22 may account for the ability to rapidly evolve escape mutants by selecting for leukemic clones that not require these target antigens for continued expansion.

Modification of T cells with chimeric antigen receptors (CAR) has emerged as a promising treatment modality for human malignancies. Integration of co-stimulatory domains into CARs can augment the activation and function of genetically targeted T cells against tumors. However, the potential for insertional mutagenesis and toxicities due to the infused cells have made development of safe methods for removing transferred cells an important consideration. We have genetically modified human T cells with a lentiviral vector to express a CD20-CAR containing both CD28 and CD137 co-stimulatory domains, a \"suicide gene\" relying on inducible activation of caspase 9 (iC9), and a truncated CD19 selectable marker. Rapid expansion (2000 fold) of the transduced T cells was achieved in 28 days after stimulation with artificial antigen presenting cells. Transduced T cells exhibited effective CD20-specific cytotoxic activity in vitro and in a mouse xenograft tumor model. Activation of the iC9 suicide switch resulted in efficient removal of transduced T cells both in vitro and in vivo. Our work demonstrates the feasibility and promise of this approach for treating CD20(+) malignancies in a safe and more efficient manner. A phase I clinical trial using this approach in patients with relapsed indolent B-NHL is planned.

BackgroundThe role of B-lymphocytes in solid tumours is unclear. Tumour biology studies have implied both anti- and pro-tumoural effects and prognostic studies have mainly linked B-cells to increased survival. This study aimed to analyse the clinical relevance of B-lymphocytes in renal cell cancer (RCC), where information on the prognostic impact is lacking.MethodsFollowing immunohistochemistry (IHC) stainings with a CD20 antibody, density of CD20+ B-cells was quantified in an RCC discovery- and validation cohort. Associations of B-cell infiltration, determined by CD20 expression or a B-cell gene-signature, and survival was also analysed in 14 publicly available gene expression datasets of cancer, including the kidney clear cell carcinoma (KIRC) dataset.ResultsIHC analyses of the discovery cohort identified a previously unrecognised subgroup of RCC patients with high infiltration of CD20+ B-cells. The B-cell-high subgroup displayed significantly shorter survival according to uni- and multi-variable analyses. The association between poor prognosis and high density of CD20+ B-cells was confirmed in the validation cohort. Analyses of the KIRC gene expression dataset using the B-cell signature confirmed findings from IHC analyses. Analyses of other gene expression datasets, representing 13 different tumour types, indicated that the poor survival-association of B-cells occurred selectively in RCC.ConclusionThis exploratory study identifies a previously unrecognised poor-prognosis subset of RCC with high density of CD20-defined B-cells.

PurposeThe purpose of the study was to evaluate protein expression of PD-L1 and CD20 as prognostic biomarkers of patient outcome in inflammatory breast cancer (IBC) samples.MethodsPD-L1 and CD20 protein expression was measured by immunohistochemistry in 221 pretreatment IBC biopsies. PD-L1 was assessed in tumor cells (PD-L1+ tumor cells) and tumor stromal infiltrating lymphocytes (PD-L1+ TILs); CD20 was scored in tumor-infiltrating B cells. Kaplan–Meier curves and Cox proportional hazard models were used for survival analysis.ResultsPD-L1+ tumor cells, PD-L1+ TILs, and CD20+ TILs were found in 8%, 66%, and 62% of IBC, respectively. PD-L1+ tumor cells strongly correlated with high TILs, pathological complete response (pCR), CD20+ TILs, but marginally with breast cancer-specific survival (BCSS, P = 0.057). PD-L1+ TILs strongly correlated with high TILs, CD20+ TILs, and longer disease-free survival (DFS) in all IBC and in triple-negative (TN) IBC (P < 0.035). IBC and TN IBC patients with tumors containing both CD20+ TILs and PD-L1+ TILs (CD20+TILs/PD-L1+TILs) showed longer DFS and improved BCSS (P < 0.002) than patients lacking both, or those with either CD20+ TILs or PD-L1+ TILs alone. In multivariate analyses, CD20+TILs/PD-L1+TILs status was an independent prognostic factor for DFS in IBC (hazard ratio (HR): 0.53, 95% CI 0.37–0.77) and TN IBC (HR: 0.39 95% CI 0.17–0.88), and for BCSS in IBC (HR: 0.60 95% CI 0.43–0.85) and TN IBC (HR: 0.38 95% CI 0.17–0.83).ConclusionCD20+TILs/PD-L1+TILs status represents an independent favorable prognostic factor in IBC and TN IBC, suggesting a critical role for B cells in antitumor immune responses. Anti-PD-1/PD-L1 and B cell-activating immunotherapies should be explored in these settings.

Loss of CD20 is a major obstacle for the retreatment of relapsed/refractory diffuse large B cell lymphoma (DLBCL) with Rituximab-associated regimens. Histone deacetylation causes gene silencing and inhibits CD20 expression. Chidamide is a novel inhibitor for histone deacetylases (HDACs). We hypothesize that Chidamide could overcome Rituximab-mediated down-regulation of CD20 and facilitate Rituximab-induced killing. In this study, we determine the mechanism of synergy of Chidamide with Rituximab in DLBCL using in vitro and in vivo models. We found that the levels of CD20 protein surface expression on five DLBCL cell lines were significantly and positively correlated with the sensitivities of cells to Rituximab. Treatment with Rituximab significantly reduced CD20 surface expression at the protein levels. RNA sequencing showed that Chidamide significantly increased expression of more than 2000 transcriptomes in DLBCL cells, around 1000 transcriptomes belong to the cell membrane and cell periphery pathways, including MS4A1. Chidamide significantly increased CD20 surface expression in DLBCL cell lines. Combination with Chidamide significantly synergized Rituximab-induced cell death in vitro and significantly inhibited tumour growth in DLBCL-bearing xenograft mice. A patient with relapsed/refractory DLBCL achieved a complete response after three cycles combined treatment with Chidamide and Rituximab. In conclusion, our data demonstrate for the first time that inhibition of HDACs by Chidamide significantly enhanced Rituximab-induced tumour growth inhibition in vitro and in vivo. We propose that CD20 surface expression should be used clinically to evaluate treatment response in patients with DLBCL. Chidamide is a promising sensitizer for the retreatment of DLBCL with Rituximab.

CD19-targeted chimeric antigen receptor (CAR) T cell therapies have driven a paradigm shift in the treatment of relapsed/refractory B-cell malignancies. However, >50% of CD19-CAR-T-treated patients experience progressive disease mainly due to antigen escape and low persistence. Clinical prognosis is heavily influenced by CAR-T cell function and systemic cytokine toxicities. Furthermore, it remains a challenge to efficiently, cost-effectively, and consistently manufacture clinically relevant numbers of virally engineered CAR-T cells. Using a highly efficient piggyBac transposon-based vector, Quantum pBac ™ ( qPB ), we developed a virus-free cell-engineering system for development and production of multiplex CAR-T therapies. Here, we demonstrate in vitro and in vivo that consistent, robust and functional CD20/CD19 dual-targeted CAR-T stem cell memory (CAR-T SCM ) cells can be efficiently produced for clinical application using qPB ™. In particular, we showed that qPB ™-manufactured CAR-T cells from cancer patients expanded efficiently, rapidly eradicated tumors, and can be safely controlled via an iCasp9 suicide gene-inducing drug. Therefore, the simplicity of manufacturing multiplex CAR-T cells using the qPB ™ system has the potential to improve efficacy and broaden the accessibility of CAR-T therapies.

Background Recently, new and advanced techniques have been adopted to design and produce nanobodies, which are used in diagnostic and immunotherapy treatments. Traditionally, nanobodies are prepared from camelid immune libraries that require animal treatments. However, such approaches require large library sizes and complicated selection procedures. The current study has employed CDR grafting and site-directed mutagenesis techniques to create genetically engineered nanobodies against the tumor marker CD20 (anti-CD20 nanobodies) used in leukemia treatment. Methods and results In this study, we utilized the swapping method to graft CDRs from the VH Rituximab antibody to VHH CDRs. We aimed to enhance the binding affinity of the nanobodies by substituting the amino acids (Y101R-Y102R-Y107R) in the VHH-CDR3. To assess the binding capacity of the mutated nanobodies, we conducted an ELISA test. Moreover, through flow cytometry analysis, we compared the fluorescence intensity of the grafted CD20 and mutant nanobodies with that of the commercially available human anti-CD20 in Raji cells. The results showed a significant difference in the fluorescence intensity of the grafted nanobodies and mutant nanobodies when compared to the commercially available human anti-CD20. Conclusion The approach we followed in this study makes it possible to create multiple anti-CD20 nanobodies with varying affinities without the need for extensive selection efforts. Additionally, our research has demonstrated that computational tools are highly reliable in designing functional nanobodies.

CD20 was the first B cell differentiation antigen identified, and CD20-specific mAbs are commonly used for the treatment of B cell malignancies and autoantibody-mediated autoimmune diseases. Despite this the role of CD20 in human B cell physiology has remained elusive. We describe here a juvenile patient with CD20 deficiency due to a homozygous mutation in a splice junction of the CD20 gene (also known as MS4A1) that results in \"cryptic\" splicing and nonfunctional mRNA species. Analysis of this patient has led us to conclude that CD20 has a central role in the generation of T cell-independent (TI) antibody responses. Key evidence to support this conclusion was provided by the observation that although antigen-independent B cells developed normally in the absence of CD20 expression, antibody formation, particularly after vaccination with TI antigens, was strongly impaired in the patient. Consistent with this, TI antipolysaccharide B cell responses were severely impeded in CD20-deficient mice. Our study therefore identifies what we believe to be a novel type of humoral immunodeficiency caused by CD20 deficiency and characterized by normal development of antigen-independent B cells, along with a reduced capacity to mount proper antibody responses.

Immunotherapy with CD123-specific T-cell engager proteins or with T cells expressing CD123-specific chimeric antigen receptors is actively being pursued for acute myeloid leukemia. T cells secreting bispecific engager molecules (ENG-T cells) may present a promising alternative to these approaches. To evaluate therapeutic potential, we generated T cells to secrete CD123/CD3-bispecific engager molecules. CD123-ENG T cells recognized primary acute myeloid leukemia (AML) cells and cell lines in an antigen-dependent manner as judged by cytokine production and/or tumor killing, and redirected bystander T cells to AML cells. Infusion of CD123-ENG T cells resulted in regression of AML in xenograft models conferring a significant survival advantage of treated mice in comparison to mice that received control T cells. At high effector to target ratios, CD123-ENG T cells recognized normal hematopoietic stem and progenitor cells (HSPCs) with preferential recognition of HSPCs from cord blood compared to bone marrow. We therefore introduced the CD20 suicide gene that can be targeted in vivo with rituximab into CD123-ENG T cells. The expression of CD20 did not diminish the anti-AML activity of CD123-ENG T cells, but allowed for rituximab-mediated ENG-T cell elimination. Thus, ENG-T cells coexpressing CD20 suicide and CD123 engager molecules may present a promising immunotherapeutic approach for AML.