MAP Kinase Phosphatase-2 Plays a Critical Role in Response to Infection by Leishmania mexicana

In this study we generated a novel dual specific phosphatase 4 (DUSP4) deletion mouse using a targeted deletion strategy in order to examine the role of MAP kinase phosphatase-2 (MKP-2) in immune responses. Lipopolysaccharide (LPS) induced a rapid, time and concentration-dependent increase in MKP-2 protein expression in bone marrow-derived macrophages from MKP-2+/+ but not from MKP-2−/− mice. LPS-induced JNK and p38 MAP kinase phosphorylation was significantly increased and prolonged in MKP-2−/− macrophages whilst ERK phosphorylation was unaffected. MKP-2 deletion also potentiated LPS-stimulated induction of the inflammatory cytokines, IL-6, IL-12p40, TNF-α, and also COX-2 derived PGE2 production. However surprisingly, in MKP-2−/− macrophages, there was a marked reduction in LPS or IFNγ-induced iNOS and nitric oxide release and enhanced basal expression of arginase-1, suggesting that MKP-2 may have an additional regulatory function significant in pathogen-mediated immunity. Indeed, following infection with the intracellular parasite Leishmania mexicana, MKP-2−/− mice displayed increased lesion size and parasite burden, and a significantly modified Th1/Th2 bias compared with wild-type counterparts. However, there was no intrinsic defect in MKP-2−/− T cell function as measured by anti-CD3 induced IFN-γ production. Rather, MKP-2−/− bone marrow-derived macrophages were found to be inherently more susceptible to infection with Leishmania mexicana, an effect reversed following treatment with the arginase inhibitor nor-NOHA. These findings show for the first time a role for MKP-2 in vivo and demonstrate that MKP-2 may be essential in orchestrating protection against intracellular infection at the level of the macrophage

Pancreatic Cancer. Experimental and Clinical Studies

Background: Pancreatic cancer is one of the most lethal of known cancers and the only treatment with possibility of cure is surgery. The costs associated with treatment of pancreatic cancer are reputably high, both in terms of morbidity and financially. To reinforce decision making there is a need to assess the costs and benefits of current treatment. Furthermore, the incitements to develop therapeutic alternatives and biologically characterize individual tumors are considerable. Methods: Evaluation of effects of proteasome inhibition on intracellular signaling systems using in vitro and in vivo experiments. Estimation of achieved utilities and direct healthcare costs based on a clinical cohort. Assessment of prognostic significance of structural genomic aberrations using comparative genomic hybridization and single nucleotide polymorphism analysis on resected tumor tissue. Results: Proteasome inhibition activated an antiapoptotic and mitogenic therapy resistance response in several mediators (EGFR, JNK, ERK and PI3K/Akt) and the inhibition of Akt and JNK increased the tumoricidal effect of proteasome inhibitors. The activation was EGFR independent and the increased cell death was not NF-κB mediated. Patients undergoing resections with curative aim and patients receiving palliative care both experienced decreased health related quality of life in all SF-36 dimensions at diagnosis, without apparent improvement over time. The cost of treatment for patients undergoing surgery was two times the cost for the palliative patients (€50,950 vs. €23,701). Interestingly, already after one year the achieved QALY was twice as large in the resection group (0.48 vs. 0.20) resulting in cost per QALY neutralization between groups. DNA copy number alterations were seen in 2p11.2, 3q24, 8p11.22, 14q11.2 and 22q11.21. No convincing specific aberrations of prognostic value were found. Short survival was however responsible for 67% of total copy number variation and associated with significantly more amplifications, possibly related to alterations in chromosome 2, 11 and 21. Conclusions: Proteasome inhibition is a promising adjunct in horizontal targeted therapy regimens and the effect may be potentiated by simultaneous inhibition of signaling systems. Costs for pancreatic cancer surgery are comparable to other major healthcare interventions and long term survival in a few is effectively increasing cost-effectiveness on patient group basis. DNA from patients with poor prognosis contains more amplifications and seems to be generally more degenerated possibly indicating a greater genomic instability. The pancreatic cancer mutational profile is displaying vast inter-individual heterogeneity and most mutations are probably passengers

Proteasome inhibition activates epidermal growth factor receptor (EGFR) and EGFR-independent mitogenic kinase signaling pathways in pancreatic cancer cells

Abstract Purpose: In the current study, we investigate the activation of antiapoptotic signaling pathways in response to proteasome inhibitor treatment in pancreatic cancer and evaluate the use of concomitant inhibition of these pathways to augment proteasome inhibitor treatment responses. Experimental Design: Pancreatic cancer cell lines and mouse flank xenografts were treated with proteasome inhibitor alone or in combination with chemotherapeutic compounds (gemcitabine, erlotinib, and bevacizumab), induction of apoptosis and effects on tumor growth were assessed. The effect of bortezomib (a first-generation proteasome inhibitor) and NPI-0052 (a second-generation proteasome inhibitor) treatment on key pancreatic mitogenic and antiapoptotic pathways [epidermal growth factor receptor, extracellular signal-regulated kinase, and phosphoinositide-3-kinase (PI3K)/AKT] was determined and the ability of inhibitors of these pathways to enhance the effects of proteasome inhibition was assessed in vitro and in vivo

The Antitumor Activity of IMGN529, a CD37-Targeting Antibody-Drug Conjugate, Is Potentiated by Rituximab in Non-Hodgkin Lymphoma Models

Naratuximab emtansine (IMGN529) is an investigational antibody-drug conjugate consisting of a CD37-targeting antibody conjugated to the maytansine-derived microtuble disruptor, DM1. IMGN529 has shown promising preclinical and clinical activity in non-Hodgkin lymphoma, including diffuse large B-cell lymphoma (DLBCL). Due to the aggressive nature of the disease, DLBCL is often treated with combination therapies to maximize clinical outcomes; therefore, we investigated the potential of combining IMGN529 with both standard-of-care and emerging therapies against multiple oncology-relevant targets and pathways. The strongest enhancement in potency was seen with anti-CD20 antibodies, including rituximab. The combination of IMGN529 and rituximab was more potent than either agent alone, and this combinatorial benefit was associated with increased apoptotic induction and cell death. Additional studies revealed that rituximab treatment increased the internalization and degradation of the CD37-targeting antibody moiety of IMGN529. The combination of IMGN529 and rituximab was highly efficacious in multiple xenograft models, with superior antitumor efficacy seen compared to either agent alone or treatment with R-CHOP therapy. These findings suggest a novel mechanism whereby the potency of IMGN529 can be enhanced by CD20 binding, which results in the increased internalization and degradation of IMGN529 leading to the generation of greater amounts of cytotoxic catabolite. Overall, these data provide a biological rationale for the enhanced activity of IMGN529 in combination with rituximab and support the ongoing clinical evaluation of IMGN529 in combination with rituximab in patients with relapsed and/or refractory DLBCL

IMGN779, a Novel CD33-targeting antibody–drug conjugate with DNA-alkylating activity, exhibits potent antitumor activity in models of AML

The myeloid differentiation antigen CD33 has long been exploited as a target for antibody-based therapeutic approaches in acute myeloid leukemia (AML). Validation of this strategy was provided with the approval of the CD33-targeting antibody–drug conjugate (ADC) gemtuzumab ozogamicin in 2000; the clinical utility of this agent, however, has been hampered by safety concerns. Thus, the full potential of CD33-directed therapy in AML remains to be realized, and considerable interest exists in the design and development of more effective ADCs that confer high therapeutic indices and favorable tolerability profiles. Here, we describe the preclinical characterization of a novel CD33-targeting ADC, IMGN779, which utilizes a unique DNA-alkylating payload to achieve potent antitumor effects with good tolerability. The payload, DGN462, is prototypical of a novel class of purpose-created indolinobenzodiazeprine pseudodimers, termed IGNs. With low picomolar potency, IMGN779 reduced viability in a panel of AML cell lines in vitro. Mechanistically, the cytotoxic activity of IMGN779 involved DNA damage, cell-cycle arrest, and apoptosis consistent with the mode of action of DGN462. Moreover, IMGN779 was highly active against patient-derived AML cells, including those with adverse molecular abnormalities, and sensitivity correlated to CD33 expression levels. In vivo, IMGN779 displayed robust antitumor efficacy in multiple AML xenograft and disseminated disease models, as evidenced by durable tumor regressions and prolonged survival. Taken together, these findings identify IMGN779 as a promising new candidate for evaluation as a novel therapeutic in AML