Nanobody based dual specific CARs

Recent clinical trials have shown that adoptive chimeric antigen receptor (CAR) T cell therapy is a very potent and possibly curative option in the treatment of B cell leukemias and lymphomas. However, targeting a single antigen may not be sufficient, and relapse due to the emergence of antigen negative leukemic cells may occur. A potential strategy to counter the outgrowth of antigen escape variants is to broaden the specificity of the CAR by incorporation of multiple antigen recognition domains in tandem. As a proof of concept, we here describe a bispecific CAR in which the single chain variable fragment (scFv) is replaced by a tandem of two single-antibody domains or nanobodies (nanoCAR). High membrane nanoCAR expression levels are observed in retrovirally transduced T cells. NanoCARs specific for CD20 and HER2 induce T cell activation, cytokine production and tumor lysis upon incubation with transgenic Jurkat cells expressing either antigen or both antigens simultaneously. The use of nanobody technology allows for the production of compact CARs with dual specificity and predefined affinity

T-cells with a single tumor antigen-specific T-cell receptor can be generated in vitro from clinically relevant stem cell sources

Chimeric antigen receptor (CAR) T-cells have shown great promise in the treatment of B-cell malignancies. For acute myeloid leukemia (AML), however, the optimal target surface antigen has yet to be discovered. Alternatively, T-cell receptor (TCR)-redirected T-cells target intracellular antigens, marking a broader territory of available target antigens. Currently, adoptive TCR T-cell therapy uses peripheral blood lymphocytes for the introduction of a transgenic TCR. However, this can cause graft-versus-host disease, due to mispairing of introduced and endogenous TCR chains. Therefore, we started from hematopoietic stem and progenitor cells (HSPC), that do not express a TCR yet, isolated from healthy donors, patients in remission after chemotherapy and AML patients at diagnosis. Using the OP9-DL1 in vitro co-culture system and agonist selection, TCR-transduced HSPC develop into mature tumor antigen-specific T-cells with only one TCR. We show here that this approach is feasible with adult HSPC from clinically relevant sources, albeit with slower maturation and lower cell yield compared to cord blood HSPC. Moreover, cryopreservation of HSPC does not have an effect on cell numbers or functionality of the generated T-cells. In conclusion, we show here that it is feasible to generate TA-specific T-cells from HSPC from adult healthy donors and patients and we believe these T-cells could be of use as a very valuable form of patient-tailored T-cell immunotherapy

Human thymic CD10+ PD-1+ intraepithelial lymphocyte precursors acquire interleukin-15 responsiveness at the CD1a– CD95+ CD28– CCR7– developmental stage

Human thymic CD8αα+ CD10+ PD-1+ αβ T cells selected through early agonist selection have been proposed as the putative thymic precursors of the human CD8αα+ intestinal intraepithelial lymphocytes (IELs). However, the progeny of these thymic precursor cells in human blood or tissues has not yet been characterized. Here, we studied the phenotypical and transcriptional differentiation of the thymic IEL precursor (IELp) lineage upon in vitro exposure to cytokines prominent in the peripheral tissues such as interleukin-15 (IL-15) and the inflammatory cytokines interleukin-12 (IL-12) and interleukin-18 (IL-18). We showed that only the CD1a− fraction of the CD10+ PD-1+ IELp population was able to proliferate with IL-15, suggesting that this subset had acquired functionality. These cells downregulated PD-1 expression and completely lost CD10 expression, whereas other surface markers such as CD95 and CXCR3 remained highly expressed. RNA-seq analysis of the IL-15-cultured cells clearly showed induction of innate-like and effector genes. Induction of the cytotoxic machinery by the CD10+ PD-1+ population was acquired in the presence of IL-15 and was further augmented by inflammatory cytokines. Our data suggest that only the CD1a− CD10+ PD-1+ population exits the thymus and survives in the periphery. Furthermore, PD-1 and CD10 expression is not an intrinsic property of this lineage, but rather characterizes a transient stage in differentiation. CD95 and CXCR3 expression combined with the absence of CD28, CCR7, and CD6 expression might be more powerful markers to define this lineage in the periphery

Rapid and effective generation of nanobody based CARs using PCR and Gibson Assembly

Recent approval of chimeric antigen receptor (CAR) T cell therapy by the European Medicines Agency (EMA)/Federal and Drug Administration (FDA) and the remarkable results of CAR T clinical trials illustrate the curative potential of this therapy. While CARs against a multitude of different antigens are being developed and tested (pre)clinically, there is still a need for optimization. The use of single -chain variable fragments (scFvs) as targeting moieties hampers the quick generation of functional CARs and could potentially limit the efficacy. Instead, nanobodies may largely circumvent these difficulties. We used an available nanobody library generated after immunization of llamas against Cluster of Differentiation (CD) 20 through DNA vaccination or against the ectodomain of CD33 using soluble protein. The nanobody specific sequences were amplified by PCR and cloned by Gibson Assembly into a retroviral vector containing two different second -generation CAR constructs. After transduction in T cells, we observed high cell membrane nanoCAR expression in all cases. Following stimulation of nanoCAR-expressing T cells with antigen-positive cell lines, robust T cell activation, cytokine production and tumor cell lysis both in vitro and in vivo was observed. The use of nanobody technology in combination with PCR and Gibson Assembly allows for the rapid and effective generation of compact CARs

The Wiskott–Aldrich syndrome protein is required for positive selection during T-cell lineage differentiation

The Wiskott–Aldrich syndrome (WAS) is an X-linked primary immune deficiency caused by a mutation in the WAS gene. This leads to altered or absent WAS protein (WASp) expression and function resulting in thrombocytopenia, eczema, recurrent infections, and autoimmunity. In T cells, WASp is required for immune synapse formation. Patients with WAS show reduced numbers of peripheral blood T lymphocytes and an altered T-cell receptor repertoire. In vitro, their peripheral T cells show decreased proliferation and cytokine production upon aCD3/aCD28 stimulation. It is unclear whether these T-cell defects are acquired during peripheral activation or are, in part, generated during thymic development. Here, we assessed the role of WASp during T-cell differentiation using artificial thymic organoid cultures and in the thymus of humanized mice. Although CRISPR/Cas9 WAS knockout hematopoietic stem and progenitor cells (HSPCs) rearranged the T-cell receptor and differentiated to T-cell receptor (TCR)+ CD4+ CD8+ double-positive (DP) cells similar to wild-type HSPCs, a partial defect in the generation of CD8 single-positive (SP) cells was observed, suggesting that WASp is involved in their positive selection. TCR repertoire analysis of the DP and CD8+ SP population, however, showed a polyclonal repertoire with no bias toward autoreactivity. To our knowledge, this is the first study of the role of WASp in human T-cell differentiation and on TCR repertoire generation

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

In vitro OP9-DL1 co-culture and subsequent maturation in the presence of IL-21 generates tumor antigen-specific T cells with a favorable less-differentiated phenotype and enhanced functionality

T cell receptor (TCR)-redirected T cells target intracellular antigens such as Wilms' tumor 1 (WT1), a tumor-associated antigen overexpressed in several malignancies, including acute myeloid leukemia (AML). For both chimeric antigen receptor (CAR)- and TCR-redirected T cells, several clinical studies indicate that T cell subsets with a less-differentiated phenotype (e.g. stem cell memory T cells, T-SCM) survive longer and mediate superior anti-tumor effects in vivo as opposed to more terminally differentiated T cells. Cytokines added during in vitro and ex vivo culture of T cells play an important role in driving the phenotype of T cells for adoptive transfer. Using the OP9-DL1 co-culture system, we have shown previously that we are able to generate in vitro, starting from clinically relevant stem cell sources, T cells with a single tumor antigen (TA)-specific TCR. This method circumvents possible TCR chain mispairing and unwanted toxicities that might occur when introducing a TA-specific TCR in peripheral blood lymphocytes. We now show that we are able to optimize our in vitro culture protocol, by adding IL-21 during maturation, resulting in generation of TA-specific T cells with a less-differentiated phenotype and enhanced in vitro anti-tumor effects. We believe the favorable T-SCM-like phenotype of these in vitro generated T cells preludes superior in vivo persistence and anti-tumor efficacy. Therefore, these TA-specific T cells could be of use as a valuable new form of patient-tailored T cell immunotherapy for malignancies for which finding a suitable CAR-T target antigen is challenging, such as AML

Gene editing-based targeted integration for correction of Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is a severe X-linked primary immunodeficiency resulting from a diversity of mutations distributed across all 12 exons of the WAS gene. WAS encodes a hematopoietic-specific and developmentally regulated cytoplasmic protein (WASp). The objective of this study was to develop a gene correction strategy potentially applicable to most WAS patients by employing nuclease-mediated, site-specific integration of a corrective WAS gene sequence into the endogenous WAS chromosomal locus. In this study, we demonstrate the ability to target the integration of WAS2-12-containing constructs into intron 1 of the endogenous WAS gene of primary CD34+ hematopoietic stem and progenitor cells (HSPCs), as well as WASp-deficient B cell lines and WASp-deficient primary T cells. This intron 1 targeted integration (TI) approach proved to be quite efficient and restored WASp expression in treated cells. Furthermore, TI restored WASp-dependent function to WAS patient T cells. Edited CD34+ HSPCs exhibited the capacity for multipotent differentiation to various hematopoietic lineages in vitro and in transplanted immunodeficient mice. This methodology offers a potential editing approach for treatment of WAS using patient’s CD34+ cells