ABSTRACT
Background: Secondary lymphoid organs provide the adequate microenvironment for the development of antigen (Ag)-specific immune responses. The tight collaboration between CD4+ T cells and B cells in germinal centers is crucial to shape B cell fate and optimize antibody maturation. Dissecting these immune interactions remains challenging in humans, and animal models do not always recapitulate human physiology. To address this issue, we developed an in vitro 3D model of a human lymphoid organ. The model relies on a microfluidic device, enabling primary human cells to self-organize in an extracellular matrix (ECM) under continuous fluid perfusion. We applied this Lymphoid Organ-Chip (LO chip) system to the analysis of B cell recall responses to SARS-CoV-2 antigens. Method(s): We used a two-channel microfluidic Chip S1 from Emulate, where the top channel is perfused with antigen (spike protein or SARS-CoV-2 mRNA vaccine), while the bottom channel contains PBMC (n = 14 independent donors) seeded at high-density in a collagen-based ECM. Immune cell division and cluster formation were monitored by confocal imaging, plasmablast differentiation and spike-specific B cell amplification by flow cytometry, antibody secretion by a cell-based binding assay (S-flow). Result(s): Chip perfusion with the SARS-CoV-2 spike protein for 6 days resulted in the induction CD38hiCD27hi plasmablast maturation compared to an irrelevant BSA protein (P< 0.0001). Using fluorescent spike as a probe, we observed a strong amplification of spike-specific B cell (from 3.7 to 140-fold increase). In line with this rapid memory B cell response, spike-specific antibodies production could be detected as early as day 6 of culture. Spike perfusion also induced CD4+ T cell activation (CD38+ ICOS+), which correlated with the level of B cell maturation. The magnitude of specific B cell amplification in the LO chip was higher than in 2D and 3D static cultures at day 6, showing the added value of 3D perfused culture for the induction of recall responses. Interestingly, the perfusion of mRNA-based SARS-CoV-2 vaccines also led to strong B cell maturation and specific B cell amplification, indicating that mRNA-derived spike could be expressed and efficiently presented in the LO chip. Conclusion(s): We developed a versatile Lymphoid Organ-Chip model suitable for the rapid evaluation of B cell recall responses. The model is responsive to protein and mRNA-encoded antigens, highlighting its potential in the evaluation of SARS-CoV-2 vaccine boosting strategies.
ABSTRACT
Background: Lorigerlimab (MGD019) is an investigational, bispecific Fc-bearing (IgG4) DART molecule designed to enhance CTLA-4 blockade on dual expressing, tumor infiltrating lymphocytes, while maintaining maximal PD-1 blockade on PD-1 expressing cells. Lorigerlimab has approximate dose proportional PK across 1-10 mg/kg IV dosing Q3W, with sustained PD-1 receptor occupancy evident at doses >=1 mg/kg Q3W. MGD019-01 is a global first-in-human dose finding and activity estimating study of lorigerlimab in advanced solid tumors (AST). Method(s): The exp phase of MGD019-01 evaluates single agent safety, PK, and antitumor effects of lorigerlimab at the recommended dose for exp of 6 mg/ kg IV Q3W in 4 tumor specific cohorts. Confirmed responses were noted in each cohort. Preliminary results of the mCRPC cohort are reported here. Response evaluable pts received >=1 dose and had >=1 postbaseline imaging evaluation. Measurable lesions were evaluated per RECIST v1.1 and skeletal metastases assessed by bone scan. Prostate specific antigen (PSA) response was defined as a >=50% (PSA50) or>=90% (PSA90) PSA decline from baseline with confirmation>=3 weeks later. Expression of proliferation marker, Ki67, and inducible costimulator (ICOS) by peripheral T cells was assessed by flow cytometry. Result(s): At data cutoff (9/10/22), 127 pts with AST received >=1 dose of lorigerlimab 6 mg/ kg. Median exposure was 10 weeks (range, 0.1, 94.4) with median of 4 infusions. 6 pts remain on therapy;36 discontinued for PD (n=13), AEs (n=17), or patient/physician decision (n=6). Treatment related adverse events (TRAE) occurred in 109/127 (85.8%) pts. TRAEs occurring in>=15% of pts were fatigue, pruritus, hypothyroidism, pyrexia. Rates of grade >=3 TRAEs and immune-related AEs were 32.3% and 7.9%, respectively. AEs leading to drug discontinuation occurred in 22.8% of pts. There were no fatal AEs related to lorigerlimab. In the mCRPC exp cohort (n=42), pts had a median of 2 prior lines of therapy for CRPC, >80% received prior ART or taxanes;88% had visceral (liver, 26%;lung, 26%) or nodal disease and 95% had bone metastases. 42 pts were PSA response evaluable;35 were RECIST evaluable. ORR was 25.7% (9/35;9 confirmed PRs). Median duration of response was 16.1 weeks (range 6-25+ weeks). 5 responders remain on study, 4 discontinued for unrelated fatal AEs: COVID-19 (2) cardiac arrest (1) C. difficile infection (1). Confirmed PSA50 and PSA90 response rates were 28.6%(12/42) and 21.4% (9/42), respectively. Increased frequencies of Ki67+ and ICOS+ T cells were observed on day 8 posttreatment compared to pretherapy per the flow cytometry analyses from 35 pts. Conclusion(s): Lorigerlimab demonstrates a manageable safety profile with evidence of encouraging and durable antitumor activity in a chemotherapy refractory mCRPC population. Randomized evaluation of lorigerlimab in mCRPC is warranted.
ABSTRACT
Rationale: Despite the availability of pharmacologic therapies, idiopathic pulmonary fibrosis (IPF) is still a clinical challenge with several unmet needs. Robust evidence supports monocytes as cellular biomarkers of progression in IPF. Yet, their precise role and whether specific subtypes might predict progression and drive disease is unknown. We reported, for the first time, that myeloidderived suppressor cells (MDSC), immature precursors of monocytes, are increased in numbers, functionally active in IPF. Monocytic MDSC is the predominant subtype in IPF, and yet, functional characterization and immune modulation properties have not been explored. Methods and Results: characterization of circulating myeloid populations in IPF by multicolor FACS confirmed the abundance of MDSC (Lin-, HLA-DRlo, CD33+, CD14+, S100A+, CD28L1+ and ICOSL+) in IPF (n=78) and fILD (n=83), also abundant in whole blood scRNA seq of severe Covid-19 patients that progressed into fibrosis, and not in mild Covid-19. Then, we prospectively followed 83 fILD patients (45% IPF, 55% non-IPF -EAA, CTD-ILD, NSIP-) over 1 year and immunophenotyped them every 3 months. Cross-sectional analysis showed that patients with a higher number circulating MDSC, had a higher GAP index (7-8) (p<0,001). Longitudinal follow-up showed that patients with constant higher circulating MDSC had lower transplant-free survival (p=0.0058). Primary isolated MDSC when co-cultured with autologous T cells induced CD8+ T cell exhaustion (PD1hi, Lag3hi, Tim3hi, TNFalpha lo, INFglo), and downregulation of co-stimulatory T cell signaling (CD28, ICOS, ITK, and LCK), preliminary data support the induction of de-novo FoxP3 Treg formation, creating a suppressive and immunosenescent microenvironment in IPF. FACS analysis of explanted lungs demonstrated the increase of tissue-resident MDSC in fibrosis (HP, NSIP, IPF) compared with donor lungs, as well as in bleomycin-induced fibrosis compared to PBS. Conclusion: Taking together, a high number of circulating MDSC reflects worse lung function and higher GAP index in cross-sectional analysis, and associates with lower transplant-free survival longitudinally. The role that immature and mature monocytes play during promotion of a suppressive microenvironment in IPF is an unexplored area that may lead to a paradigm shift in our understanding of the sequelae of exhaustion and immunosenescence, contributing to the identification of novel targets useful for therapeutic myeloid selection in IPF.