Durable response after tisagenlecleucel in adults with relapsed/refractory follicular lymphoma: ELARA trial update.

ABSTRACT: Tisagenlecleucel is approved for adults with relapsed/refractory (r/r) follicular lymphoma (FL) in the third- or later-line setting. The primary analysis (median follow-up, 17 months) of the phase 2 ELARA trial reported high response rates and excellent safety profile in patients with extensively pretreated r/r FL. Here, we report longer-term efficacy, safety, pharmacokinetic, and exploratory biomarker analyses after median follow-up of 29 months (interquartile range, 22.2-37.7). As of 29 March 2022, 97 patients with r/r FL (grades 1-3A) received tisagenlecleucel infusion (0.6 × 108-6 × 108 chimeric antigen receptor-positive viable T cells). Bridging chemotherapy was allowed. Baseline clinical factors, tumor microenvironment, blood soluble factors, and circulating blood cells were correlated with clinical response. Cellular kinetics were assessed by quantitative polymerase chain reaction. Median progression-free survival (PFS), duration of response (DOR), and overall survival (OS) were not reached. Estimated 24-month PFS, DOR, and OS rates in all patients were 57.4% (95% confidence interval [CI], 46.2-67), 66.4% (95% CI, 54.3-76), and 87.7% (95% CI, 78.3-93.2), respectively. Complete response rate and overall response rate were 68.1% (95% CI, 57.7-77.3) and 86.2% (95% CI, 77.5-92.4), respectively. No new safety signals or treatment-related deaths were reported. Low levels of tumor-infiltrating LAG3+CD3+ exhausted T cells and higher baseline levels of naïve CD8+ T cells were associated with improved outcomes. Tisagenlecleucel continued to demonstrate highly durable efficacy and a favorable safety profile in this extended follow-up of 29 months in patients with r/r FL enrolled in ELARA. This trial was registered at www.clinicaltrials.gov as #NCT03568461.

Two distinct mechanisms underlie progesterone-induced proliferation in the mammary gland.

The mouse mammary gland develops postnatally under the control of female reproductive hormones. Estrogens and progesterone trigger morphogenesis by poorly understood mechanisms acting on a subset of mammary epithelial cells (MECs) that express their cognate receptors, estrogen receptor alpha (ERalpha) and progesterone receptor (PR). Here, we show that in the adult female, progesterone drives proliferation of MECs in two waves. The first, small wave, encompasses PR(+) cells and requires cyclin D1, the second, large wave, comprises mostly PR(-) cells and relies on the tumor necrosis factor (TNF) family member, receptor activator of NF-kappaB-ligand (RANKL). RANKL elicits proliferation by a paracrine mechanism. Ablation of RANKL in the mammary epithelium blocks progesterone-induced morphogenesis, and ectopic expression of RANKL in MECs completely rescues the PR(-/-) phenotype. Systemic administration of RANKL triggers proliferation in the absence of PR signaling, and injection of a RANK signaling inhibitor interferes with progesterone-induced proliferation. Thus, progesterone elicits proliferation by a cell-intrinsic and a, more important, paracrine mechanism.

Profibrotic potential of prominin-1+ epithelial progenitor cells in pulmonary fibrosis.

BACKGROUND: In idiopathic pulmonary fibrosis loss of alveolar epithelium induces inflammation of the pulmonary tissue followed by accumulation of pathogenic myofibroblasts leading eventually to respiratory failures. In animal models inflammatory and resident cells have been demonstrated to contribute to pulmonary fibrosis. Regenerative potential of pulmonary and extra-pulmonary stem and progenitor cells raised the hope for successful treatment option against pulmonary fibrosis. Herein, we addressed the contribution of lung microenvironment and prominin-1(+) bone marrow-derived epithelial progenitor cells in the mouse model of bleomycin-induced experimental pulmonary fibrosis. METHODS: Prominin-1(+) bone marrow-derived epithelial progenitors were expanded from adult mouse lungs and differentiated in vitro by cytokines and growth factors. Pulmonary fibrosis was induced in C57Bl/6 mice by intratracheal instillation of bleomycin. Prominin-1(+) progenitors were administered intratracheally at different time points after bleomycin challenge. Green fluorescence protein-expressing cells were used for cell tracking. Cell phenotypes were characterized by immunohistochemistry, flow cytometry and quantitative reverse transcription-polymerase chain reaction. RESULTS: Prominin-1(+) cells expanded from healthy lung represent common progenitors of alveolar type II epithelial cells, myofibroblasts, and macrophages. Administration of prominin-1(+) cells 2 hours after bleomycin instillation protects from pulmonary fibrosis, and some of progenitors differentiate into alveolar type II epithelial cells. In contrast, prominin-1(+) cells administered at day 7 or 14 lose their protective effects and differentiate into myofibroblasts and macrophages. Bleomycin challenge enhances accumulation of bone marrow-derived prominin-1(+) cells within inflamed lung. In contrast to prominin-1(+) cells from healthy lung, prominin-1(+) precursors isolated from inflamed organ lack regenerative properties but acquire myofibroblast and macrophage phenotypes. CONCLUSION: The microenvironment of inflamed lung impairs the regenerative capacity of bone marrow-derived prominin-1(+) progenitors and promotes their differentiation into pathogenic phenotypes.

Heart-infiltrating prominin-1+/CD133+ progenitor cells represent the cellular source of transforming growth factor beta-mediated cardiac fibrosis in experimental autoimmune myocarditis.

RATIONALE: Myocardial fibrosis is a hallmark of inflammation-triggered end-stage heart disease, a common cause of heart failure in young patients. OBJECTIVE: We used CD4(+) T-cell-mediated experimental autoimmune myocarditis model to determine the parameters regulating cardiac fibrosis in inflammatory heart disease. METHODS AND RESULTS: alpha-Myosin heavy chain peptide/complete Freund's adjuvant immunization was used to induce experimental autoimmune myocarditis in BALB/c mice. Chimeric mice, reconstituted with enhanced green fluorescence protein (EGFP)(+) bone marrow, were used to track the fate of inflammatory cells. Prominin-1(+) cells were isolated from the inflamed hearts, cultured in vitro and injected intracardially at different stages of experimental autoimmune myocarditis. Transforming growth factor (TGF)-beta-mediated fibrosis was addressed using anti-TGF-beta antibody treatment. Myocarditis peaked 21 days after immunization and numbers of cardiac fibroblasts progressively increased on follow-up. In chimeric mice, >60% of cardiac fibroblasts were EGFP(+) 46 days after immunization. At day 21, cardiac infiltrates contained approximately 30% of prominin-1(+) progenitors. In vitro and in vivo experiments confirmed that prominin-1(+) but not prominin-1(-) cells isolated from acutely inflamed hearts represented the cellular source of cardiac fibroblasts at late stages of disease, characterized by increased TGF-beta levels within the myocardium. Mechanistically, the in vitro differentiation of heart-infiltrating prominin-1(+) cells into fibroblasts depended on TGF-beta-mediated phosphorylation of Smad proteins. Accordingly, anti-TGF-beta antibody treatment prevented myocardial fibrosis in immunized mice. CONCLUSIONS: Taken together, heart-infiltrating prominin-1(+) progenitors are the major source of subsequent TGF-beta-triggered cardiac fibrosis in experimental autoimmune myocarditis. Recognizing the critical, cytokine-dependent role of bone marrow-derived progenitors in cardiac remodeling might result in novel treatment concepts against inflammatory heart failure.

Prominin-1/CD133+ lung epithelial progenitors protect from bleomycin-induced pulmonary fibrosis.

RATIONALE: The mouse model of bleomycin-induced lung injury offers an approach to study idiopathic pulmonary fibrosis, a progressive interstitial lung disease with poor prognosis. Progenitor cell-based treatment strategies might combine antiinflammatory effects and the capacity for tissue repair. OBJECTIVES: To expand progenitor cells with reparative and regenerative capacities and to evaluate their protective effects on pulmonary fibrosis in vivo. METHODS: Prominin-1/CD133(+) epithelial progenitor cells (PEPs) were expanded from adult mouse lungs after digestion and culture of distal airways. Lung fibrosis was induced in C57Bl/6 mice by instillation of bleomycin. Two hours later, animals were transplanted with PEPs. Inflammation and fibrosis were assessed by immunohistochemistry, bronchoalveolar lavage fluid differentials, and real-time polymerase chain reaction. MEASUREMENTS AND MAIN RESULTS: PEPs expanded from mouse lungs were of bone marrow origin, coexpressed stem and hematopoietic cell markers, and differentiated in vitro into alveolar type II surfactant protein-C(+) epithelial cells. In bleomycin-challenged mice, intratracheally injected PEPs engrafted into the lungs and differentiated into type II pneumocytes. Furthermore, PEPs suppressed proinflammatory and profibrotic gene expression, prevented the recruitment of inflammatory cells, and protected bleomycin-challenged mice from pulmonary fibrosis. Mechanistically, the protective effect depended on upregulation of inducible nitric oxide synthase in PEPs and nitric oxide-mediated suppression of alveolar macrophage proliferation. Accordingly, PEPs from iNOS(-/-) but not iNOS(+/+) mice failed to protect from bleomycin-induced lung injury. CONCLUSIONS: The combined antiinflammatory and regenerative capacity of bone marrow-derived pulmonary epithelial progenitors offers a promising approach for development of cell-based therapeutic strategies against pulmonary fibrosis.

Interferon-gamma regulates idiopathic pneumonia syndrome, a Th17+CD4+ T-cell-mediated graft-versus-host disease.

RATIONALE: Pulmonary complications of hematopoietic stem cell transplantation include infections and graft-versus-host diseases, such as idiopathic pneumonia syndrome (IPS). Conflicting data exist regarding the role of the interferon (IFN)-gamma-producing Th1 CD4(+) T-cell subset and IL-17A in IPS. OBJECTIVES: To determine the role of IFN-gamma and IL-17A in the establishment of pulmonary graft-versus-host disease. METHODS: A semiallogeneic murine model based on C57BL/6 x BALB/c as recipients with transplantation of BALB/c RAG2(-/-) bone marrow and transfer of different genetic knockout T cells (T-bet(-/-), IFN-gamma(-/-), IFN-gammaR(-/-)) on a BALB/c background. Lung tissue was examined for parenchymal changes and infiltrating cells by histology and fluorescence-activated cell sorter analysis. MEASUREMENTS AND MAIN RESULTS: After transfer of semiallogeneic bone marrow together with donor CD4(+) T cells lacking IFN-gamma or T-bet-a T-box transcription factor controlling Th1 commitment-we found severe inflammation in the lungs, but no enhancement in other organs. In contrast, wild-type donor CD4(+) T cells mediated minimal inflammation only, and donor CD8(+) T cells were not required for IPS development. Mechanistically, the absence of IFN-gamma or IFN-gamma signaling in pulmonary parenchymal cells promoted expansion of IL-17A-producing CD4(+) T cells and local IL-17A release. In vivo depletion of IL-17A reduced disease severity. CONCLUSIONS: One mechanism of IFN-gamma protection against IPS is negative regulation of the expansion of pathogenic IL-17A-producing CD4(+) T cells through interaction with the IFN-gamma receptor on the pulmonary parenchymal cell population.

Determination of liver specific toxicities in rat hepatocytes by high content imaging during 2-week multiple treatment.

DILI is a major safety issue during drug development and one of the leading causes for market withdrawal. Despite many efforts made in the past, the prediction of DILI using in vitro models remains very unreliable. In the present study, the well-established hepatocyte Collagen I-Matrigel™ sandwich culture was used, mimicking chronic drug treatment after multiple incubations for 14 days. Ten drugs associated with different types of specific preclinical and clinical liver injury were evaluated at non-cytotoxic concentrations. Mrp2-mediated transport, intracellular accumulation of neutral lipids and phospholipids were selected as functional endpoints by using Cellomics™ Arrayscan® technology and assessed at five timepoints (day 1, 3, 7, 10, 14). Liver specific functional impairments after drug treatment were enhanced over time and could be monitored by HCI already after few days and before cytotoxicity. Phospholipidosis-inducing drugs Chlorpromazine and Amiodarone displayed the same response as in vivo. Cyclosporin A, Chlorpromazine, and Troglitazone inhibited Mrp2-mediated biliary transport, correlating with in vivo findings. Steatosis remained difficult to be reproduced under the current in vitro testing conditions, resulting into false negative and positive responses. The present results suggest that the repeated long-term treatment of rat hepatocytes in the Collagen I-Matrigel™ sandwich configuration might be a suitable tool for safety profiling of the potential to induce phospholipidosis and impair Mrp2-mediated transport processes, but not to predict steatosis.

Vaccination with Flt3L-induced CD8α+ dendritic cells prevents CD4+ T helper cell-mediated experimental autoimmune myocarditis.

Experimental autoimmune myocarditis (EAM) represents a CD4(+) T helper (Th) cell-mediated mouse model of inflammatory heart disease. Interferon (IFN)-γ, typically produced by Th1 cells, reduces EAM severity in myosin heavy-chain-(MyHC)-α peptide/Complete Freund adjuvant-immunized mice. Thus, developing a vaccination strategy that promotes differentiation of Th1 cells may be beneficial in EAM. FMS-like tyrosine kinase 3 ligand (Flt3L)-induced splenic CD8α(+) dendritic cells (DC), which produce interleukin (IL)-12p35, were identified to selectively induce biased differentiation towards Th1. Mice vaccinated with MyHC-α-loaded Flt3L-induced splenic CD8α(+) DC were protected from EAM. In contrast, when Flt3L-induced splenic CD8α(+) DC were pre-stimulated and over-activated with LPS and αCD40 antibodies or loaded with unspecific OVA(323-339) peptide instead of MyHC-α peptide, mice developed similar disease scores as non-vaccinated controls. Vaccination efficacy depended on IFN-γ, since CD8α(+)-vaccinated IFN-γR(-/-) mice were not protected. Importantly, splenic CD8α(+) vaccination was independent of regulatory T cells. Taken together, Flt3L-induced dendritic cell-based antigen-specific vaccination limits expansion of auto-reactive Th cells and protects mice from autoimmune heart inflammation.

CD11b+ monocytes abrogate Th17 CD4+ T cell-mediated experimental autoimmune myocarditis.

Experimental autoimmune myocarditis (EAM) represents a Th17 T cell-mediated mouse model of postinflammatory heart disease. In BALB/c wild-type mice, EAM is a self-limiting disease, peaking 21 days after alpha-myosin H chain peptide (MyHC-alpha)/CFA immunization and largely resolving thereafter. In IFN-gammaR(-/-) mice, however, EAM is exacerbated and shows a chronic progressive disease course. We found that this progressive disease course paralleled persistently elevated IL-17 release from T cells infiltrating the hearts of IFN-gammaR(-/-) mice 30 days after immunization. In fact, IL-17 promoted the recruitment of CD11b(+) monocytes, the major heart-infiltrating cells in EAM. In turn, CD11b(+) monocytes suppressed MyHC-alpha-specific Th17 T cell responses IFN-gamma-dependently in vitro. In vivo, injection of IFN-gammaR(+/+)CD11b(+), but not IFN-gammaR(-/-)CD11b(+), monocytes, suppressed MyHC-alpha-specific T cells, and abrogated the progressive disease course in IFN-gammaR(-/-) mice. Finally, coinjection of MyHC-alpha-specific, but not OVA-transgenic, IFN-gamma-releasing CD4(+) Th1 T cell lines, together with MyHC-alpha-specific Th17 T cells protected RAG2(-/-) mice from EAM. In conclusion, CD11b(+) monocytes play a dual role in EAM: as a major cellular substrate of IL-17-induced inflammation and as mediators of an IFN-gamma-dependent negative feedback loop confining disease progression.