ADCT-402, a PBD dimer-containing antibody drug conjugate targeting CD19-expressing malignancies

Human CD19 antigen is a 95-kDa type I membrane glycoprotein in the immunoglobulin superfamily whose expression is limited to the various stages of B-cell development and differentiation and is maintained in the majority of B-cell malignancies, including leukemias and non-Hodgkin lymphomas of B-cell origin. Coupled with its differential and favourable expression profile, CD19 has rapid internalization kinetics and it is not shed into the circulation, making it an ideal target for the development of antibody-drug conjugates (ADCs) to treat B-cell malignancies. ADCT-402 (loncastuximab tesirine) is a novel CD19-targeted ADC delivering SG3199, a highly cytotoxic DNA minor groove interstrand cross-linking pyrrolobenzodiazepine (PBD) dimer warhead. It showed potent and highly targeted in vitro cytotoxicity in CD19-expressing human cell lines. ADCT-402 was specifically bound, internalized and trafficked to lysosomes in CD19-expressing cells and following release of warhead, resulted in formation of DNA cross-links which persisted for 36 h. Bystander killing of CD19-negative cells by ADCT-402 was also observed. In vivo, single doses of ADCT-402 resulted in highly potent, dose-dependent anti-tumor activity in several subcutaneous and disseminated human tumor models with marked superiority to comparator ADCs delivering tubulin inhibitors. Dose-dependent DNA cross-links and γ-H2AX DNA damage response were measured in tumors by 24 h after single dose administration, while matched PBMCs showed no evidence of DNA damage. Pharmacokinetic analysis in rat and cynomolgus monkey showed excellent stability and tolerability of ADCT-402 in vivo. Together, these impressive data were used to support the clinical testing of this novel ADC in patients with CD19-expressing B-cell malignancies

ADCT-301, a Pyrrolobenzodiazepine (PBD) Dimer-Containing Antibody-Drug Conjugate (ADC) Targeting CD25-Expressing Hematological Malignancies

Despite the many advances in the treatment of hematologic malignancies over the past decade, outcomes in refractory lymphomas remain poor. One potential strategy in this patient population is the specific targeting of IL2R-α (CD25), which is overexpressed on many lymphoma and leukemic cells, using antibody–drug conjugates (ADC). ADCT-301 is an ADC composed of human IgG1 HuMax-TAC against CD25, stochastically conjugated through a dipeptide cleavable linker to a pyrrolobenzodiazepine (PBD) dimer warhead with a drug–antibody ratio (DAR) of 2.3. ADCT-301 binds human CD25 with picomolar affinity. ADCT-301 has highly potent and selective cytotoxicity against a panel of CD25-expressing human lymphoma cell lines. Once internalized, the released warhead binds in the DNA minor groove and exerts its potent cytotoxic action via the formation of DNA interstrand cross-links. A strong correlation between loss of viability and DNA cross-link formation is demonstrated. DNA damage persists, resulting in phosphorylation of histone H2AX, cell-cycle arrest in G2–M, and apoptosis. Bystander killing of CD25-negative cells by ADCT-301 is also observed. In vivo, a single dose of ADCT-301 results in dose-dependent and targeted antitumor activity against both subcutaneous and disseminated CD25-positive lymphoma models. In xenografts of Karpas 299, which expressed both CD25 and CD30, marked superiority over brentuximab vedotin (Adcetris) is observed. Dose-dependent increases in DNA cross-linking, γ-H2AX, and PBD payload staining were observed in tumors in vivo indicating a role as relevant pharmacodynamic assays. Together, these data support the clinical testing of this novel ADC in patients with CD25-expressing tumors

Grafted Human Embryonic Progenitors Expressing Neurogenin-2 Stimulate Axonal Sprouting and Improve Motor Recovery after Severe Spinal Cord Injury

7 p.Background: Spinal cord injury (SCI) is a widely spread pathology with currently no effective treatment for any symptom. Regenerative medicine through cell transplantation is a very attractive strategy and may be used in different non-exclusive ways to promote functional recovery. We investigated functional and structural outcomes after grafting human embryonic neural progenitors (hENPs) in spinal cord-lesioned rats.Methods and Principal Findings: With the objective of translation to clinics we have chosen a paradigm of delayed grafting, i.e., one week after lesion, in a severe model of spinal cord compression in adult rats. hENPs were either naive or engineered to express Neurogenin 2 (Ngn2). Moreover, we have compared integrating and non-integrating lentiviral vectors, since the latter present reduced risks of insertional mutagenesis. We show that transplantation of hENPs transduced to express Ngn2 fully restore weight support and improve functional motor recovery after severe spinal cord compression at thoracic level. This was correlated with partial restoration of serotonin innervations at lumbar level, and translocation of 5HT1A receptors to the plasma membrane of motoneurons. Since hENPs were not detectable 4 weeks after grafting, transitory expression of Ngn2 appears sufficient to achieve motor recovery and to permit axonal regeneration. Importantly, we also demonstrate that transplantation of naive hENPs is detrimental to functional recovery.Conclusions and Significance: Transplantation and short-term survival of Ngn2-expressing hENPs restore weight support after SCI and partially restore serotonin fibers density and 5HT1A receptor pattern caudal to the lesion. Moreover, grafting of naive-hENPs was found to worsen the outcome versus injured only animals, thus pointing to the possible detrimental effect of stem cell-based therapy per se in SCI. This is of major importance given the increasing number of clinical trials involving cell grafting developed for SCI patients.This study was supported by the European Union FP6 "RESCUE" STREP; the "Institut pour la Recherche sur la Moelle Epiniere"; the "Academie de Medecine"; the "Societe Francaise de Neurochirurgie"; "Verticale" and the "Association Demain Debout Aquitaine". The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Differential cell reaction upon Toll-like receptor 4 and 9 activation in human alveolar and lung interstitial macrophages

BACKGROUND: Investigations on pulmonary macrophages (MΦ) mostly focus on alveolar MΦ (AM) as a well-defined cell population. Characteristics of MΦ in the interstitium, referred to as lung interstitial MΦ (IM), are rather ill-defined. In this study we therefore aimed to elucidate differences between AM and IM obtained from human lung tissue. METHODS: Human AM and IM were isolated from human non-tumor lung tissue from patients undergoing lung resection. Cell morphology was visualized using either light, electron or confocal microscopy. Phagocytic activity was analyzed by flow cytometry as well as confocal microscopy. Surface marker expression was measured by flow cytometry. Toll-like receptor (TLR) expression patterns as well as cytokine expression upon TLR4 or TLR9 stimulation were assessed by real time RT-PCR and cytokine protein production was measured using a fluorescent bead-based immunoassay. RESULTS: IM were found to be smaller and morphologically more heterogeneous than AM, whereas phagocytic activity was similar in both cell types. HLA-DR expression was markedly higher in IM compared to AM. Although analysis of TLR expression profiles revealed no differences between the two cell populations, AM and IM clearly varied in cell reaction upon activation. Both MΦ populations were markedly activated by LPS as well as DNA isolated from attenuated mycobacterial strains (M. bovis H37Ra and BCG). Whereas AM expressed higher amounts of inflammatory cytokines upon activation, IM were more efficient in producing immunoregulatory cytokines, such as IL10, IL1ra, and IL6.CONCLUSION: AM appear to be more effective as a non-specific first line of defence against inhaled pathogens, whereas IM show a more pronounced regulatory function. These dissimilarities should be taken into consideration in future studies on the role of human lung MΦ in the inflammatory response

Interrelationship between Dendritic Cell Trafficking and Francisella tularensis Dissemination following Airway Infection

Francisella tularensis, the etiological agent of the inhalation tularemia, multiplies in a variety of cultured mammalian cells. Nevertheless, evidence for its in vivo intracellular residence is less conclusive. Dendritic cells (DC) that are adapted for engulfing bacteria and migration towards lymphatic organs could serve as potential targets for bacterial residence and trafficking. Here, we focus on the in vivo interactions of F. tularensis with DC following airway infection of mice. Lethal airway infection of mice with the live vaccine strain (LVS) results in trafficking of a CD11bhigh/CD11cmed/autofluorescencelow DC subset from the respiratory tract to the draining mediastinal lymph node (MdLN). Simultaneously, a rapid, massive bacterial colonization of the MdLN occurs, characterized by large bacterial foci formation. Analysis of bacteria in the MdLN revealed a major population of extracellular bacteria, which co-exists with a substantial fraction of intracellular bacteria. The intracellular bacteria are viable and reside in cells sorted for DC marker expression. Moreover, in vivo vital staining experiments indicate that most of these intracellular bacteria (∼75%) reside in cells that have migrated from the airways to the MdLN after infection. The correlation between DC and bacteria accumulation in the MdLN was further demonstrated by manipulating DC migration to the MdLN through two independent pathways. Impairment of DC migration to the MdLN, either by a sphingosine-1-phosphate receptor agonist (FTY720) or by the D prostanoid receptor 1 agonist (BW245C), resulted in reduced bacterial colonization of MdLN. Moreover, BW245C treatment delayed the onset of morbidity and the time to death of the infected mice. Taken together, these results suggest that DC can serve as an inhabitation niche for F. tularensis in the early stages of infection, and that DC trafficking plays a role in pathogen dissemination. This underscores the therapeutic potential of DC migration impairing drugs in tularemia treatment

Gender differences in the use of cardiovascular interventions in HIV-positive persons; the D:A:D Study

Peer reviewe

Interaction between environmental temperature and hypoxia on central and peripheral fatigue during high-intensity dynamic knee extension

This paper was accepted for publication in the journal Journal of Applied Physiology and the definitive published version is available at http://dx.doi.org/10.1152/japplphysiol.00876.2015This study investigated causative factors behind the expression of different interaction types during exposure to multi-stressor environments. Neuromuscular fatigue rates and time to exhaustion (TTE) were investigated in active males (n=9) exposed to three climates (5°C,50%-rh/23°C,50%-rh/42°C,70%-rh) at two inspired oxygen fractions (0.209/0.125 FIO2; equivalent attitude=4100 m). After 40-mins rest in the environmental conditions, participants performed constant workload (high-intensity) knee extension exercise until exhaustion, with brief assessments of neuromuscular function every 110-s. Independent exposure to cold, heat and hypoxia significantly (p<0.01) reduced TTE from thermoneutral-normoxia (reduction of 190, 405, 505-s from 915-s respectively). The TTE decrease was consistent with a faster rate of peripheral fatigue development (p<0.01) compared with thermoneutral-normoxia (increase of 1.6, 3.1 and 4.9%.min-1 from 4.1%.min-1 respectively). Combined exposure to hypoxic-cold resulted in an even greater TTE reduction (-589-seconds), likely due to an increase in the rate of peripheral fatigue development (increased by 7.6%.min-1), but this without significant interaction between stressors (p>0.198). In contrast, combined exposure to hypoxic-heat reduced TTE by 609-s, showing a significant antagonistic interaction (p=0.003) similarly supported by an increased rate of peripheral fatigue development (increased by 8.3%.min-1). A small decline (<0.4%.min-1) in voluntary muscle activation was only observed in thermoneutral-normoxia. In conclusion, interaction type is influenced by the impact magnitude of the individual stressors' effect on exercise capacity, whereby the greater the stressors impact, the greater the probability that one stressor will be abolished by the other. This indicates humans respond to severe and simultaneous physiological strains based on a 'worst strain takes precedence' principle