The long and winding road to biomarkers for immunotherapy: a retrospective analysis of samples from patients with triple-negative breast cancer treated with pembrolizumab

BACKGROUND

Immune checkpoint blockade (ICB) in combination with chemotherapy improves outcome of patients with triple-negative breast cancer (TNBC) in metastatic and early settings. The identification of predictive biomarkers able to guide treatment decisions is challenging and currently limited to programmed death-ligand 1 (PD-L1) expression and high tumor mutational burden (TMB) in the advanced setting, with several limitations.

MATERIALS AND METHODS

We carried out a retrospective analysis of clinical-pathological and molecular characteristics of tumor samples from 11 patients with advanced TNBC treated with single-agent pembrolizumab participating in two early-phase clinical trials: KEYNOTE-012 and KEYNOTE-086. Clinical, imaging, pathological [i.e. tumor-infiltrating lymphocytes (TILs), PD-L1 status], RNA sequencing, and whole-exome sequencing data were analyzed. We compared our results with publicly available transcriptomic data from TNBC cohorts from TCGA and METABRIC.

RESULTS

Response to pembrolizumab was heterogeneous: two patients experienced exceptional long-lasting responses, six rapid progressions, and three relatively slower disease progression. Neither PD-L1 nor stromal TILs were significantly associated with response to treatment. Increased TMB values were observed in tumor samples from exceptional responders compared to the rest of the cohort (P = 3.4 × 10-4). Tumors from exceptional responders were enriched in adaptive and innate immune cell signatures. Expression of regulatory T-cell markers (FOXP3, CCR4, CCR8, TIGIT) was mainly observed in tumors from responders except for glycoprotein-A repetitions predominant (GARP), which was overexpressed in tumors from rapid progressors. GARP RNA expression in primary breast tumors from the public dataset was significantly associated with a worse prognosis.

CONCLUSIONS

The wide spectrum of clinical responses to ICB supports that TNBC is a heterogeneous disease. Tumors with high TMB respond better to ICB. However, the optimal cut-off of 10 mutations (mut)/megabase (Mb) may not reflect the complexity of all tumor subtypes, despite its approval as a tumor-agnostic biomarker. Further studies are required to better elucidate the relevance of the tumor microenvironment and its components as potential predictive biomarkers in the context of ICB.

The Impact of Standard vs Early Apical Release Holmium Laser Enucleation of the Prostate Technique on Postoperative Incontinence and Quality of Life

OBJECTIVE

To investigate the difference in postoperative incontinence and quality of life comparing standard vs early apical release (EAR) Holmium Laser Enucleation of the Prostate (HoLEP).

METHODS

A retrospective review was performed to identify patients who underwent HoLEP from December 2021 to December 2022 at a single tertiary referral center with two participating consultant urologists. Patients were assessed with questionnaires and evaluated clinically. We performed propensity score matching with a logistic regression and a 1:1 matching method. A propensity score-adjusted logistic regression (PSRM) was performed to compare the pads per day between surgical techniques controlling for age, prostate size, preoperative survey data, uroflow, and postvoid residual.

RESULTS

One hundred fourteen patients underwent HoLEP, of which 60 patients were treated with EAR and 54 patients with standard technique. EAR technique demonstrated shorter operative times (P = .046). The EAR cohort demonstrated improved AUASS (P = .034, P = .001), QOL (P = .001, P <.001), and continence rates (P <.001, P <.001) at 6 and 12weeks postoperatively. PSRM showed that the standard HoLEP increased the risk of requiring ≥2 pads per day 4.2x (P = .031, HR 95%, CI=1.16, 15.35) and 8.3x (P <.001, HR 95% CI 3.17, 21.6) at 6 and 12weeks postoperatively.

CONCLUSION

EAR technique promoted earlier return of continence and improved quality of life within 6weeks of surgery.

Leveraging big data of immune checkpoint blockade response identifies novel potential targets

BACKGROUND

The development of immune checkpoint blockade (ICB) has changed the way we treat various cancers. While ICB produces durable survival benefits in a number of malignancies, a large proportion of treated patients do not derive clinical benefit. Recent clinical profiling studies have shed light on molecular features and mechanisms that modulate response to ICB. Nevertheless, none of these identified molecular features were investigated in large enough cohorts to be of clinical value.

MATERIALS AND METHODS

Literature review was carried out to identify relevant studies including clinical dataset of patients treated with ICB [anti-programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1), anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) or the combination] and available sequencing data. Tumor mutational burden (TMB) and 37 previously reported gene expression (GE) signatures were computed with respect to the original publication. Biomarker association with ICB response (IR) and survival (progression-free survival/overall survival) was investigated separately within each study and combined together for meta-analysis.

RESULTS

We carried out a comparative meta-analysis of genomic and transcriptomic biomarkers of IRs in over 3600 patients across 12 tumor types and implemented an open-source web application (predictIO.ca) for exploration. TMB and 21/37 gene signatures were predictive of IRs across tumor types. We next developed a de novo GE signature (PredictIO) from our pan-cancer analysis and demonstrated its superior predictive value over other biomarkers. To identify novel targets, we computed the T-cell dysfunction score for each gene within PredictIO and their ability to predict dual PD-1/CTLA-4 blockade in mice. Two genes, F2RL1 (encoding protease-activated receptor-2) and RBFOX2 (encoding RNA-binding motif protein 9), were concurrently associated with worse ICB clinical outcomes, T-cell dysfunction in ICB-naive patients and resistance to dual PD-1/CTLA-4 blockade in preclinical models.

CONCLUSION

Our study highlights the potential of large-scale meta-analyses in identifying novel biomarkers and potential therapeutic targets for cancer immunotherapy.

Clinical significance of CD73 in triple-negative breast cancer: multiplex analysis of a phase III clinical trial

Background

CD73 is an ecto-enzyme that promotes tumor immune escape through the production of immunosuppressive extracellular adenosine in the tumor microenvironment. Several CD73 inhibitors and adenosine receptor antagonists are being evaluated in phase I clinical trials.

Patients and methods

Full-face sections from formalin-fixed paraffin-embedded primary breast tumors from 122 samples of triple-negative breast cancer (TNBC) from the BIG 02-98 adjuvant phase III clinical trial were included in our analysis. Using multiplex immunofluorescence and image analysis, we assessed CD73 protein expression on tumor cells, tumor-infiltrating leukocytes and stromal cells. We investigated the associations between CD73 protein expression with disease-free survival (DFS), overall survival (OS) and the extent of tumor immune infiltration.

Results

Our results demonstrated that high levels of CD73 expression on epithelial tumor cells were significantly associated with reduced DFS, OS and negatively correlated with tumor immune infiltration (Spearman's R= -0.50, P < 0.0001). Patients with high levels of CD73 and low levels of tumor-infiltrating leukocytes had the worse clinical outcome.

Conclusions

Taken together, our study provides further support that CD73 expression is associated with a poor prognosis and reduced anti-tumor immunity in human TNBC and that targeting CD73 could be a promising strategy to reprogram the tumor microenvironment in this BC subtype.

Role of robot-assisted retroperitoneal lymph node dissection in malignant mesothelioma of the tunica vaginalis: case series and review of the literature

INTRODUCTION

The management of malignant mesothelioma of the tunica vaginalis (MMTVT) is not clearly defined. Retroperitoneal lymph node dissection has been reported as a potential management option. Herein we present our experience with robot-assisted retroperitoneal lymph node dissection (RARPLND) in our series of patients with MMTVT.

MATERIALS AND METHODS

The Mayo Clinic cancer registry was queried from 1972-present for all patients who had a diagnosis of MMTVT. Six patients were identified, five of whom were treated with RPLND, where four underwent RARPLND.

RESULTS

In five patients who underwent RPLND, the median age was 50 years (IQR 34-51). Four patients originally presented with right sided symptomatic hydroceles, while one presented with right sided chronic epididymitis. Orchiectomy (one simple, two inguinal radical) was performed in three patients prior to presentation. Preoperative cross-sectional imaging, including PET-CT scan in three patients, was negative for lymphadenopathy or metastasis. RARPLND was performed in 4/5 (80%) cases and concomitant hemiscrotectomy in 4/5 (80%) cases. Full bilateral template was performed in three patients and right modified template was performed in the remaining two. Median lymph node yield was 29 (IQR 22-32) and median blood loss was 275 cc (IQR 200-300). Positive retroperitoneal lymph nodes were found in 3/5 (60%) cases. All patients who underwent RARPLND were discharged home on postoperative day one. Mean follow up was 27 months (range 3-47). No patients recurred.

CONCLUSIONS

Regardless of the approach, RPLND may provide a diagnostic benefit in patients who present with MMTVT, with the robotic approach affording a potentially expedited recovery.

A network approach to developing immuno-oncology combinations in Canada

Immune checkpoint inhibitors have revolutionized care for many cancer indications, with considerable effort now being focused on increasing the rate, depth, and duration of patient response. One strategy is to combine immune strategies (for example, ctla-4 and PD-1/L1-directed agents) to harness additive or synergistic efficacy while minimizing toxicity. Despite encouraging results with such combinations in multiple tumour types, numerous clinical challenges remain, including a lack of biomarkers that reliably predict outcome, the emergence of therapeutic resistance, and optimal management of immune-related toxicities. Furthermore, the selection of ideal combinations from the myriad of immune, systemic, and locoregional therapies has yet to be determined. A longitudinal network-based approach could offer advantages in addressing those critical questions, including long-term follow-up of patients beyond individual trials. The molecular cancer registry Personalize My Treatment, managed by the Networks of Centres of Excellence nonprofit organization Exactis Innovation, is uniquely positioned to accelerate Canadian immuno-oncology (io) research efforts throughout its national network of cancer sites. To gain deeper insight into how a pan-Canadian network could advance research in io combinations, Exactis invited preeminent clinical and scientific advisors from across Canada to a roundtable event in November 2017. The present white paper captures the expert advice provided: leverage longitudinal patient data collection; facilitate network collaboration and assay harmonization; synergize with existing initiatives, networks, and biobanks; and develop an io combination trial based on Canadian discoveries.

Abstract P4-06-03: Unravelling triple-negative breast cancer tumor microenvironment heterogeneity using an integrative multiomic analysis

Introduction: Triple negative breast cancer (TNBC) constitute 10-20% of all breast cancers and is associated with a worse prognosis and limited treatment options. Recent trials evaluating immune checkpoint blockade in TNBC demonstrated encouraging results for a subset of patients. TNBC is highly heterogeneous and its tumour microenvironment (TME) has been recognized as a critical determinant of its behavior and clinical outcome. Genome-wide gene expression profiling analyses have already improved our understanding of the complexity of this disease and have defined 6 different molecular subtypes namely Basal-like 1 (BL1), basal-like 2 (BL2), immunomodulatory (IM), mesenchymal (M), mesenchymal stem-like (MSL) and luminal androgen receptor (LAR), exhibiting distinct biological and clinical characteristic.

In this study, we aim to dissect the molecular diversity of the TME and more specifically to assess the immune landscape according to TNBC molecular subtypes.

Methods: A cohort of 485 TNBC patient with publicly available data (RNA-Seq and Illumina HT-12 v3) from the METABRIC and the TCGA consortia were used in the gene expression analysis. Gene signatures reflecting different features or cellular components (immune, stromal, angiogenesis, lymphangiogenesis, hypoxia, metabolism) of the TME were used to evaluate multiple biological processes known to contribute to tumorogenesis. A compendium of 17 immune specific gene signatures and T cell localisation classification were used to evaluate the immune composition and spatial pattern of immune infiltrates. All parameters were compared using a logistic regression model to evaluate their relative contribution according to each molecular subtype.

Results: Our analyses demonstrated that each molecular subtype exhibits different TME profiles, as well as specific immune composition and localisation. IM tumors were associated with the highest expression of immune-related gene signatures, enriched with adaptive immune cells and with a fully inflamed spatial pattern. MSL tumors were mostly associated with the expression of Lymphangiogenesis and Stromal TME signatures. They also exhibited some immune activity through the expression of immune gene signatures capturing innate immune and adaptive immunosuppressive cells. This subtype was mainly associated with margin restricted and to some extent with fully inflamed spatial pattern. BL1 tumors were associated with the expression of Metabolism TME signatures, along with fully inflamed and stroma restricted spatial pattern. To a lesser extent, this subtype was also associated with activated DC and CD4 Tem cells. LAR and M tumors exhibited an immune cold phenotype. They were associated with Stromal and Metabolism TME signatures, enriched in margin restricted spatial pattern and negatively associated with every immune cells.

Conclusions: Our results demonstrate for the first time the huge heterogeneity that characterizes the TME of TNBCs. Identification of specific TME profiles could help to design more rationale and appropriate synergistic therapeutic combinations targeting TME elements in this high-risk disease.

Citation Format: Bareche Y, Buisseret L, Gruosso T, Girard E, Venet D, Dupont F, Desmedt C, Park M, Rothé F, Stagg J, Sotiriou C. Unravelling triple-negative breast cancer tumor microenvironment heterogeneity using an integrative multiomic analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-06-03.

Moth pheromone-selective projection neurons with cell bodies in the antennal lobe lateral cluster exhibit diverse morphological and neurophysiological characteristics

Olfactory projection neurons convey information from the insect antennal lobe (AL) to higher brain centers. Previous reports have demonstrated that pheromone-responsive projection neurons with cell bodies in the moth medial cell cluster (mcPNs) predominantly have dendritic arborizations in the sexually dimorphic macroglomerular complex (MGC) and send an axon from the AL to the calyces of the mushroom body (CA) as well as the lateral horn (LH) of the protocerebrum via the medial AL tract. These neurons typically exhibit a narrow odor tuning range related to the restriction of their dendritic arbors within a single glomerulus (uniglomerular). In this study, we report on the diverse physiological and morphological properties of a group of pheromone-responsive olfactory projection neurons with cell bodies in the AL lateral cell cluster (MGC lcPNs) of two closely related moth species. All pheromone-responsive lcPNs appeared to exhibit "basket-like" dendritic arborizations in two MGC compartments and made connections with various protocerebral targets including ventrolateral and superior neuropils via projections primarily through the lateral AL tract and to a lesser extent the mediolateral antennal lobe tract. Physiological characterization of MGC lcPNs also revealed a diversity of response profiles including those either enhanced by or reliant upon presentation of a pheromone blend. These responses manifested themselves as higher maximum firing rates and/or improved temporal resolution of pulsatile stimuli. MGC lcPNs therefore participate in conveying diverse olfactory information relating to qualitative and temporal facets of the pheromone stimulus to a more expansive number of protocerebral targets than their mcPN counterparts.

Abstract PD6-05: Distinct tumor microenvironments stratify triple negative breast cancer into immune subtypes

Background:

Triple negative breast cancer (TNBC) are especially difficult to treat effectively. While only 20-30% of TNBC patients respond to chemotherapy in the neoadjuvant setting, overall outcome remains poor for non-responding patients. Engaging the immune system promises optimal personalized cancer therapy as mounting evidence suggests that immune-checkpoint inhibitor immunotherapies may become a therapeutic option for TNBC patients. The presence of CD8+ T cells, a crucial component of the cytotoxic arm of the adaptive immune response, is associated with good clinical outcome in TNBC patients. Specifically, it is the efficient CD8+ T cell invasion and infiltration in the tumor that is associated with good outcome. On the other hand, some tumors accumulate CD8+ T cells in the tumor-associated stroma with poor infiltration in the tumor epithelium. These patients show poor outcome. As CD8+ T cell infiltration in the tumor is a crucial step to mount an efficient anti-tumor response, we thus wondered how the tumor microenvironment affects CD8+ T cell invasion into the tumor epithelial compartment of the TNBC tumors.

Methods:

To identify potential stroma-dependent mechanisms that potentiate or inhibit CD8+ T cells invasion into the tumor epithelium, we coupled analysis of spatial patterns of CD8+ T cell localization by Immunohistochemistry (IHC) andperformed gene expression profiling of laser-capture microdissected tumor-associated stroma (as well as matched epithelium and bulk tumor) from 38 TNBC chemotherapy-naive primary cases. GSEA-based Metasignatures were derived from bulk tumor gene expression data from our cohort. To investigate the compartment of origin of the pathways identified via the Metasignatures, the (LCM)-derived tumor stromal and epithelial gene expression were analyzed.

Results:

CD8+ T cell quantification in different compartments of the tumor identify 3 main subgroups of TNBC based on CD8+ T cell localization. Importantly we developed a 2-step classification scheme based on CD8+ T cell localization. We developed metasignatures following our 2 steps classification and identified key bulk tumor metasignatures that showed prognostic value in an independent cohort. In addition the matched LCM gene expression from the tumor epithelium and stromal compartments allowed us to identify the compartment of origin.

Importantly, while 1 group of TNBC tumor was showing a significant anti-tumor response, the 2 other groups showed absence of such environment. The 2 non inflamed immune subtypes showed distinct phenotypes and biologies associated with poor anti-tumor response that we validated by immunohistochemistry and fluorescence. These results highlight different potential mecanisms that lead to immune evasion and allow us to stratify TNBC into immune subgroups.

Citation Format: Gruosso T, Gigoux M, Bertos N, Manem VS, Zuo D, Saleg SM, Souleimanova M, Zhao H, Johnson RM, Monette A, Muñoz Ramos V, Hallett MT, Stagg J, Lapointe R, Omeroglu A, Meterissian S, Buisseret L, Van den Eyden G, Salgado R, Guiot M-C, Haibe-Kains B, Park M. Distinct tumor microenvironments stratify triple negative breast cancer into immune subtypes [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD6-05.

Abstract PD6-07: Clinical significance of CD73 expression in triple-negative breast cancer from the BIG 02-98 adjuvant phase III clinical trial

Background: CD73 is an ecto-enzyme that promotes tumor immune escape through the production of immunosuppressive extracellular adenosine in the tumor microenvironment. Several CD73 inhibitors and adenosine receptor antagonists are being evaluated in phase I clinical trials.

Objective: To investigate the prognosis significance of CD73 in human triple-negative breast cancer.

Design and setting: This is a prospective-retrospective biomarker analysis. Using multiplex immunofluorescence and image analysis, we assessed CD73 protein expression on tumor cells, tumor-infiltrating leukocytes and stromal cells on full-face sections from formalin-fixed paraffin-embedded primary breast tumors.

Participants: 122 samples of triple-negative breast cancer from the BIG 02-98 adjuvant phase III clinical trial were included in our analysis. This trial compared the addition of taxanes to anthracyclines-based chemotherapy in node-positive breast cancer.

Results: Our results demonstrated that high levels of CD73 expression on epithelial tumor cells were significantly associated with reduced disease-free survival (DFS) and overall survival (OS) in patients with triple-negative breast cancer. Using the median as a threshold between low and high levels of CD73 on epithelial cells, hazard ratios (HR) adjusted for grade, number of positive lymph nodes and tumor size, were of 2.21 (95% confidence interval (CI): 1.15-4.25); p=0.02 for DFS and of 2.47 (95%CI: 1.21-5.07); p=0.01 for OS. CD73 expression negatively correlated with tumor immune infiltration (Spearman's R= -0.50, p&lt;0.0001). Patients with high levels of CD73 and low levels of tumor-infiltrating leukocytes had the worse clinical outcome (HR: 4.24 (1.90-9.45), p&lt;0.001 for DFS, HR: 3.91 (1.65-9.31), p=0.002 for OS) compared to patients with low CD73 and high tumor-immune infiltration. Flow cytometric analysis of tumor-infiltrating leukocytes revealed a high frequency of CD73-expressing B cells and higher CD73 expression on tumor-infiltrating myeloid cells and natural killer cells compared to peripheral blood.

Conclusion and relevance: Taken together, our study provides further support that CD73 expression is associated with a poor prognosis and reduced anti-tumor immunity in human triple-negative breast cancer and that targeting CD73 could be a promising strategy to reprogram the tumor microenvironment in this breast cancer subtype.

Citation Format: Buisseret L, Pommey S, Allard B, Garaud S, Bergeron MA, Cousineau I, Ameye L, Paesmans M, Crown JPA, Di Leo A, Piccart-Gebhart M, Willard-Gallo K, Sotiriou C, Stagg J. Clinical significance of CD73 expression in triple-negative breast cancer from the BIG 02-98 adjuvant phase III clinical trial [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr PD6-07.

Immuno-oncology-101: overview of major concepts and translational perspectives

Cancer immunotherapy is demonstrating impressive clinical benefit in different malignancies and clinical oncologists are increasingly turning their attention to immune-oncology. It is now well recognized that innate and adaptive immune cells infiltrating tumors are associated with clinical outcomes and responses to treatments, and can be harnessed to patients' benefit. Considerable advances have also been made in understanding how cancers escape from immune attack. Targeting of immunological escape processes regulated by the expression of immune checkpoint receptors and ligands and the down-modulation of tumor antigen presentation is the basis of immuno-oncology treatments. Despite recent achievements, there remain a number of unresolved issues in order to successfully implement cancer immunotherapy in many cancers. Importantly, clinical biomarkers are still needed for better optimization of emerging combination immunotherapies and better treatment tailoring. In this review, we summarize the function of innate and adaptive immune cells in anti-tumor immunity and the general mechanisms exploited by tumor cells to escape and inhibit immune responses as well as therapeutic strategies developed to overcome these mechanisms and discuss emerging biomarkers in immuno-oncology.

Mechanisms of immune modulation by mesenchymal stromal cells and clinical translation

Cell therapy with mesenchymal stromal cells (MSCs) is the focus of intensive investigation. Several clinical trials, including large-scale placebo-controlled phase III clinical trials, are currently underway evaluating the therapeutic potential of autologous and allogeneic MSCs for treatment of catastrophic inflammatory diseases, including steroid-refractory graft-versus-host disease (GvHD), multiple sclerosis (MS) and Crohn's disease. MSCs are also being investigated as carriers of anti-cancer biotherapeutics. We here review recent developments in our understanding of the immunosuppressive properties of MSCs. We firstly discuss the effects of ex vivo culture conditions on the phenotype and functions of MSCs. Secondly, we summarize the immune functions suppressed by MSCs with a focus on T cell, B cell, natural killer cell and dendritic cell functions. Thirdly, we discuss newly identified pathways responsible for the immunosuppressive activity of MSCs, including the expression of heme-oxygenase (HO)-1, the secretion of galectins, CCL2 antagonism, T regulatory cell (Treg) cross-talk and production of TNF-α stimulated gene/protein-6 (TSG-6). Finally, we review the literature on the molecular pathways governing MSC homing and discuss recent clinical data on the use of MSCs for treatment of GvHD, MS and Crohn's disease.

Immune plasticity of bone marrow-derived mesenchymal stromal cells

Isolated from simple bone marrow aspirates, mesenchymal stromal cells (MSCs) can be easily expanded ex vivo and differentiated into various cell lineages. Because they are present in humans of all ages, are harvested in the absence of prior mobilization and preserve their plasticity following gene modification, MSCs are particularly attractive for cell-based medicine. One of the most fascinating properties of ex vivo expanded MSCs is their ability to suppress ongoing immune responses, both in vitro and in vivo. Although not fully understood, the immunosuppressive properties of MSCs have been reported to affect the function of a broad range of immune cells, including T cells, antigen-presenting cells, natural killer cells and B cells. Whereas successful harnessing of these immunosuppressive properties might one day open the door to the development of new cell-based strategies for the control of graft-versus-host and other autoimmune diseases, recent studies suggest that the immune-modulating properties of MSCs are far more complex than first thought. Reminiscent of the dichotomy of function of dendritic cells (DCs), which can act as potent activators or potent suppressors of immune responses, new studies including our own work has shown that MSCs in fact possess the dual ability to suppress or activate immune responses. In this review, we summarize the different biological properties of MSCs and discuss the current literature on the complex mechanism of immune modulation mediated by ex vivo expanded MSCs.

Targeting death-inducing receptors in cancer therapy

Deregulated cell death pathways may lead to the development of cancer, and induction of tumor cell apoptosis is the basis of many cancer therapies. Knowledge accumulated concerning the molecular mechanisms of apoptotic cell death has aided the development of new therapeutic strategies to treat cancer. Signals through death receptors of the tumor necrosis factor (TNF) superfamily have been well elucidated, and death receptors are now one of the most attractive therapeutic targets in cancer. In particular, DR5 and DR4, death receptors of TNF-related apoptosis-inducing ligand (TRAIL or Apo2L), are interesting targets of antibody-based therapy, since TRAIL may also bind decoy receptors that may prevent TRAIL-mediated apoptosis, whereas TRAIL ligand itself selectively induces apoptosis in cancer cells. Here, we review the potential therapeutic utility of agonistic antibodies against DR5 and DR4 and discuss the possible extension of this single-antibody-based strategy when combined with additional modalities that either synergizes to cause enhanced apoptosis or further engage the cellular immune response. Rational design of antibody-based therapies combining the induction of tumor cell apoptosis and activation of tumor-specific adaptive immunity enables promotion of distinct steps of the antitumor immune response, thereby enhancing tumor-specific lymphocytes that can eradicate TRAIL/DR5-resistant mutating, large established and heterogeneous tumors in a manner that does not require the definition of individual tumor-specific antigens.

Immune regulation by mesenchymal stem cells: two sides to the coin

Mesenchymal stem cells (MSCs) constitute a rare population of adult stem cells that can be isolated from a simple bone marrow aspirate in the absence of prior mobilization. For this reason, MSCs are particularly attractive for cell-based medicine. Ex-vivo-expanded MSCs isolated from different species, including human MSCs, have been shown to suppress the activity of a broad range of immune cells, including T cells, antigen-presenting cells, natural killer (NK) cells and B cells. New studies have further shown that MSCs interact with NK cells, express NK cell receptor ligands, express Toll-like receptors (TLRs), respond to TLR ligands and act as antigen-presenting cells upon interferon-gamma stimulation. Taken together, these studies suggest that MSCs may constitute a previously unrecognized player of the immune system with dichotomy of function reminiscent of other antigen-presenting cells. An important question that remains unanswered is whether resident MSCs actually play a role in endogenous immune responses? I here review the mechanisms of MSC-mediated immune regulation and discuss the major roles of resident MSCs in health and disease.

Genetic and structural analysis of the Bacteroides conjugative transposon CTn341

The genetic structure and functional organization of a Bacteroides conjugative transposon (CTn), CTn341, were determined. CTn341 was originally isolated from a tetracycline-resistant clinical isolate of Bacteroides vulgatus. The element was 51,993 bp long, which included a 5-bp coupling sequence that linked the transposon ends in the circular form. There were 46 genes, and the corresponding gene products fell into three major functional groups: DNA metabolism, regulation and antibiotic resistance, and conjugation. The G + C content and codon usage observed in the functional groups suggested that the groups belong to different genetic lineages, indicating that CTn341 is a composite, modular element. Mutational analysis of genes representing the different functional groups provided evidence for the gene assignments and showed that the basic conjugation and excision genes are conserved among Bacteroides spp. A group IIA1 intron, designated B.f.I1, was found to be inserted into the bmhA methylase gene. Reverse transcriptase PCR analysis of CTn341 RNA showed that B.fr.I1 was functional and was spliced out of the bmhA gene. Six related CTn-like elements were found in the genome sequences of Bacteroides fragilis NCTC9343 and Bacteroides thetaiotaomicron VPI5482. The putative elements were similar to CTn341 primarily in the tra and mob regions and in the exc gene, and several appeared to contain intron elements. Our data provide the first reported sequence for a complete Bacteroides CTn, and they should be of considerable benefit to further functional and genetic analyses of antibiotic resistance elements and genome evolution in Bacteroides.

Pseudotyped retrovectors for tumor-specific delivery of toxic suicide genes

Tumor-targeted gene transfer of the suicide gene, herpes simplex virus thymidine kinase (HSV-TK) is an extremely powerful biopharmaceutical approach for the treatment of cancer. However, no substantive clinical benefit has been reported since this concept was first developed more than a decade ago. This review summarizes the current status of human clinical trials employing viral-vector based delivery of HSV-TK as well as novel means being developed by which killing of tumor cells could be enhanced. In particular, we discuss of the use of VSV-G pseudotyped retrovectors in successfully achieving high tumor-restricted gene transfer efficiency in preclinical studies and the challenges still to be overcome to bring cancer gene therapy safely to the clinic.

Clinical experience with the Palmaz-Schatz coronary stent. Initial results of a multicenter study

Stenting of native coronary arteries with a balloon-expandable stent was attempted in 226 patients after elective angioplasty. Delivery of the device was successful in 213 (94%) of the patients. Of these, 39 received aspirin and dipyridamole only (group 1) and 174 received aspirin, dipyridamole, and warfarin for 1-3 months (group 2). There was no abrupt closure (less than or equal to 1 day) or perioperative death in either group. In-hospital or perioperative complications in group 1 compared with group 2 were as follows: subacute closure (1-14 days), seven (18%) patients versus one (0.6%) patient, respectively, p less than 0.0001; myocardial infarction, five (13%) patients versus one (0.6%) patient, respectively; condition requiring urgent bypass surgery, one (2.5%) patient versus no patients, respectively. Thus, the incidence of major complications such as death, myocardial infarction, or a condition requiring urgent bypass surgery was 15% in group 1 and 0.6% in group 2. Clinical follow-up revealed that 92% of the patients were asymptomatic at 3 months after stenting compared with 6% before stenting (p less than 0.0001). Of the 13 patients who were symptomatic, nine underwent cardiac catheterization and, ultimately, successful elective coronary angioplasty or bypass surgery. We conclude that a high delivery success rate can be expected with this device and that clinical thrombosis is less frequent in anticoagulated patients than in nonanticoagulated patients. Furthermore, in this selected patient population, coronary stenting results in a low incidence of in-hospital and perioperative complications. Clinical success, defined by absence of symptoms, appears to be sustained at 3 months.

Perilymphatic pressure in the cat. Description of a new method for study of inner ear hydrodynamics

Continuous recordings of the perilymphatic (Pp), cerebrospinal fluid (PCSF), central venous (PCV) and arterial (PA) pressures have been performed on anesthetized cats. The perilymphatic space was reached by an extraural approach that leaves the ear canal and middle ear intact. A conical canal was drilled into the temporal bone down to the vestibule. The position of the canal was later confirmed histologically. A small, threaded, metallic cannula was screwed into the bone. For pressure measurements Millar microtip transducers were used, thus giving minimum measurement volume displacement. The mean PP and PCSF were found to be equal, whereas the maximum pressure during expiration was significantly higher in the CSF. not affected by the given anesthetics. Ligation of the external jugular veins had a minor and temporary effect on the PP and PCSF. The method is considered to be suitable for studies on the inner ear hydrodynamics as well as for audiophysiological measurements with an intact middle ear transmission system.

A compact infrasound and pressure waveform generator for use with small cavities

The described apparatus is a small portable sound and pressure-step generator capable of producting pressure levels of over 150 dB into cavities of maximum volume 30 cm3. The form of the pressure waveform is an exact replica of the electrical input waveform independent of leakage and flexibility in the cavity. Complex sound waveforms can be easily produced with the aid of a function generator.

Electronic analysis of foetal breathing movements: a practical application of phase-lock-loop principles

Measurement of foetal breathing movements is becoming more common as a means of monitoring processes occurring in the human foetus. Conventional time-period analysis of breathing movements is prone to error owing to their complexity, and it is laborious to decipher any frequency pattern. The described apparatus has been designed to give an on-line visual indication of the instantaneous frequency of foetal breathing movements when measured by a time-distance recorder connected to an echoscope. It is affected insignificantly by spurious signals, and can be build cheaply with easily-available components. Practical trials suggest that frequency analysis by this device can be of value for examining episodes of continuous breathing movements in the foetus.

Pressure-regulating mechanisms in the inner ear

The perilymphatic pressure was studied in relation to pressure step variations in the external ear canal and in the middle ear. The transfer of pressure via the ossicular chain reached its limiting value at quite low pressures. When pressure steps were applied directly to the middle ear, there was almost a direct transfer of pressure for positive changes. Nonlinearities were shown between positive and negative pressure steps. The pressure-regulating ability of the inner ear was illustrated by means of calculating the time constants of the pressure transfer curves.

The treatment of recurrent ventricular tachycardia with bilateral cervico-thoracic sympathetic-ganglionectomy. A report of two cases

Two patients had bilateral cervico-thoracic sympatho-ganglionectomy for treatment of disabling symptoms due to refractory ventricular tachycardia. In both patients treatment with antiarrhythmic drugs singly, in combination, or together with pacemaker overdrive had been ineffective in controlling this arrhythmia. Both patients had normal coronary arteriograms.

Bilateral thoracic sympathectomy appears to facilitate medical management of ventricular tachycardia in selected patients who are refractory to the usual medical treatment.