Gene knock-outs in human CD34+ hematopoietic stem and progenitor cells and in the human immune system of mice

Human CD34+ hematopoietic stem and progenitor cells (HSPCs) are a standard source of cells for clinical HSC transplantations as well as experimental xenotransplantation to generate "humanized mice". To further extend the range of applications of these humanized mice, we developed a protocol to efficiently edit the genomes of human CD34+ HSPCs before transplantation. In the past, manipulating HSPCs has been complicated by the fact that they are inherently difficult to transduce with lentivectors, and rapidly lose their stemness and engraftment potential during in vitro culture. However, with optimized nucleofection of sgRNA:Cas9 ribonucleoprotein complexes, we are now able to edit a candidate gene in CD34+ HSPCs with almost 100% efficiency, and transplant these modified cells in immunodeficient mice with high engraftment levels and multilineage hematopoietic differentiation. The result is a humanized mouse from which we knocked out a gene of interest from their human immune system.

An In Vivo Model of Human Macrophages in Metastatic Melanoma

Despite recent therapeutic progress, advanced melanoma remains lethal for many patients. The composition of the immune tumor microenvironment (TME) has decisive impacts on therapy response and disease outcome, and high-dimensional analyses of patient samples reveal the heterogeneity of the immune TME. Macrophages infiltrate TMEs and generally associate with tumor progression, but the underlying mechanisms are incompletely understood. Because experimental systems are needed to elucidate the functional properties of these cells, we developed a humanized mouse model reconstituted with human immune cells and human melanoma. We used two strains of recipient mice, supporting or not supporting the development of human myeloid cells. We found that human myeloid cells favored metastatic spread of the primary tumor, thereby recapitulating the cancer-supportive role of macrophages. We next analyzed the transcriptome of human immune cells infiltrating tumors versus other tissues. This analysis identified a cluster of myeloid cells present in the TME, but not in other tissues, which do not correspond to canonical M2 cells. The transcriptome of these cells is characterized by high expression of glycolytic enzymes and multiple chemokines and by low expression of gene sets associated with inflammation and adaptive immunity. Compared with humanized mouse results, we found transcriptionally similar myeloid cells in patient-derived samples of melanoma and other cancer types. The humanized mouse model described here thus complements patient sample analyses, enabling further elucidation of fundamental principles in melanoma biology beyond M1/M2 macrophage polarization. The model can also support the development and evaluation of candidate antitumor therapies.

Building the Next Generation of Humanized Hemato-Lymphoid System Mice

Since the late 1980s, mice have been repopulated with human hematopoietic cells to study the fundamental biology of human hematopoiesis and immunity, as well as a broad range of human diseases in vivo. Multiple mouse recipient strains have been developed and protocols optimized to efficiently generate these “humanized” mice. Here, we review three guiding principles that have been applied to the development of the currently available models: (1) establishing tolerance of the mouse host for the human graft; (2) opening hematopoietic niches so that they can be occupied by human cells; and (3) providing necessary support for human hematopoiesis. We then discuss four remaining challenges: (1) human hematopoietic lineages that poorly develop in mice; (2) limited antigen-specific adaptive immunity; (3) absent tolerance of the human immune system for its mouse host; and (4) sub-functional interactions between human immune effectors and target mouse tissues. While major advances are still needed, the current models can already be used to answer specific, clinically-relevant questions and hopefully inform the development of new, life-saving therapies.

Surgical adhesions in mice are derived from mesothelial cells and can be targeted by antibodies against mesothelial markers

Peritoneal adhesions are fibrous tissues that tether organs to one another or to the peritoneal wall and are a major cause of postsurgical and infectious morbidity. The primary molecular chain of events leading to the initiation of adhesions has been elusive, chiefly due to the lack of an identifiable cell of origin. Using clonal analysis and lineage tracing, we have identified injured surface mesothelium expressing podoplanin (PDPN) and mesothelin (MSLN) as a primary instigator of peritoneal adhesions after surgery in mice. We demonstrate that an anti-MSLN antibody diminished adhesion formation in a mouse model where adhesions were induced by surgical ligation to form ischemic buttons and subsequent surgical abrasion of the peritoneum. RNA sequencing and bioinformatics analyses of mouse mesothelial cells from injured mesothelium revealed aspects of the pathological mechanism of adhesion development and yielded several potential regulators of this process. Specifically, we show that PDPN+MSLN+ mesothelium responded to hypoxia by early up-regulation of hypoxia-inducible factor 1 alpha (HIF1α) that preceded adhesion development. Inhibition of HIF1α with small molecules ameliorated the injury program in damaged mesothelium and was sufficient to diminish adhesion severity in a mouse model. Analyses of human adhesion tissue suggested that similar surface markers and signaling pathways may contribute to surgical adhesions in human patients.

Eradication of Canine Diffuse Large B-Cell Lymphoma in a Murine Xenograft Model with CD47 Blockade and Anti-CD20

Cancer immunotherapies hold much promise, but their potential in veterinary settings has not yet been fully appreciated. Canine lymphomas are among the most common tumors of dogs and bear remarkable similarity to human disease. In this study, we examined the combination of CD47 blockade with anti-CD20 passive immunotherapy for canine lymphoma. The CD47/SIRPα axis is an immune checkpoint that regulates macrophage activation. In humans, CD47 is expressed on cancer cells and enables evasion from phagocytosis. CD47-blocking therapies are now under investigation in clinical trials for a variety of human cancers. We found the canine CD47/SIRPα axis to be conserved biochemically and functionally. We identified high-affinity SIRPα variants that antagonize canine CD47 and stimulate phagocytosis of canine cancer cells in vitro When tested as Fc fusion proteins, these therapeutic agents exhibited single-agent efficacy in a mouse xenograft model of canine lymphoma. As robust synergy between CD47 blockade and tumor-specific antibodies has been demonstrated for human cancer, we evaluated the combination of CD47 blockade with 1E4-cIgGB, a canine-specific antibody to CD20. 1E4-cIgGB could elicit a therapeutic response against canine lymphoma in vivo as a single agent. However, augmented responses were observed when combined with CD47-blocking therapies, resulting in synergy in vitro and in vivo and eliciting cures in 100% of mice bearing canine lymphoma. Our findings support further testing of CD47-blocking therapies alone and in combination with CD20 antibodies in the veterinary setting. Cancer Immunol Res; 4(12); 1072-87. ©2016 AACR.

Abstract PR13: The anti-CD47 antibody Hu5F9-G4 is a novel immune checkpoint inhibitor with synergistic efficacy in combination with clinically active cancer targeting antibodies

We have recently discovered that CD47 is a checkpoint of the innate immune system. CD47 is highly expressed on many cancers, allowing evasion of immune surveillance. By binding the inhibitory receptor SIRPα on macrophages and other phagocytes, CD47 serves as a “don't eat me” signal and innate immune checkpoint. In pre-clinical models, CD47-blocking monoclonal antibodies (mAbs) inhibit human cancer growth and metastasis in many hematologic malignancies and solid tumors. Anti-CD47 mAb therapy also enables macrophages to prime and activate CD8+ T cells, which limit tumor growth even after treatment cessation. These findings formed the basis for developing an anti-CD47 mAb (Hu5F9-G4) as a new class of cancer immunotherapy that is being tested in phase 1 trials.

In addition to monotherapy efficacy, we demonstrate here in pre-clinical models that Hu5F9-G4 treatment leads to profound anti-tumor synergy with mAbs targeting tumor-specific antigens, including rituximab (anti-CD20) for non-Hodgkin's lymphoma, trastuzumab (anti-Her2) for breast cancer, and anti-EGFR mAbs for colorectal cancer (CRC). In patient-derived xenograft (PDX) models, Hu5F9-G4 combined with these cancer-specific mAbs led to synergistic tumor elimination compared to either antibody alone. This synergy is due to the simultaneous supply of a strong pro-phagocytic signal through Fc receptor-mediated antibody dependent cellular phagocytosis by the cancer targeting mAb, in combination with blockade of the anti-phagocytic signal CD47 by Hu5F9-G4. We next demonstrate that combination efficacy with Hu5F9-G4 and cancer targeting mAbs is independent of intrinsic tumor signaling pathways and resistance. Using CRC PDX models, we show that Hu5F9-G4 combined with either the anti-EGFR mAb cetuximab or panitumumab leads to synergistic tumor elimination in RAS wildtype tumors. While anti-EGFR mAbs are clinically approved in RAS wildtype metastatic CRC, they are not effective in patients with RAS mutated CRC, which represent approximately 40% of all CRC. Remarkably, the combination treatment was also synergistic against CRCs with RAS pathway mutations, in which anti-EGFR mAbs alone were not effective. Thus, the combination of Hu5F9-G4 with anti-EGFR mAbs can rescue efficacy of EGFR mAb activity in RAS mutant CRC and that synergistic efficacy is independent of mutations in intrinsic tumor signaling pathways. This strategy could be applied to other tumor types that develop signal pathway resistance. Based on these findings we have initiated a clinical development program to explore the efficacy of Hu5F9-G4 monotherapy efficacy and in combination with cancer targeting mAbs.

We are currently conducting a first-in-class, first-in-human Phase 1 dose escalation trial of Hu5F9-G4 in advanced solid tumors (NCT02216409) to determine the safety, tolerability and recommended phase 2 dose of Hu5F9-G4. In over 20 patients treated, Hu5F9-G4 has been well tolerated in the presence of multiple dose escalations. Mild anemia has been observed, which is an expected on-target effect due to CD47-mediated clearance of aged red blood cells. This anemia occurs with the first dose only, is transient, and is well managed through a priming and maintenance dose strategy. To date, no grade 3 or 4 anemias have been observed, with no patients requiring blood transfusions. Current dose levels of Hu5F9-G4 are associated with drug serum levels that achieve anti-tumor efficacy in pre-clinical models, thus demonstrating effective saturation of the internal CD47 receptor tissue sink. Future trials of Hu5F9-G4 in combination with cancer targeting mAbs are being planned.

In summary, Hu5F9-G4 represents a novel immune checkpoint therapy that engages both innate and adaptive immune systems, displays widespread synergistic efficacy in combination with cancer targeting mAbs, and can overcome tumor signaling pathway resistance. The clinical activity of Hu5F9-G4 alone and in combination is being explored.

Citation Format: Mark P. Chao, Kelly M. McKenna, Adriel Cha, Dongdong Feng, Jie Liu, Branimir I. Sikic, Ravindra Majeti, Irving L. Weissman, Chris Takimoto, Jens-Peter Volkmer. The anti-CD47 antibody Hu5F9-G4 is a novel immune checkpoint inhibitor with synergistic efficacy in combination with clinically active cancer targeting antibodies [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr PR13.

Use of questionnaire screening for vibration white finger in a high risk industrial population

OBJECTIVES

To compare the results of questionnaire screening with those of objective testing in the identification of vibration white finger (VWF) in a high risk population.

METHODS

Three groups of men (79 riveters, 52 healthy controls and 79 compensation claimants) were assessed for VWF by a detailed questionnaire covering occupational and general medical history and incorporating specific questions related to the presence or absence of relevant symptoms in their hands. Each then underwent provocative cold testing under controlled conditions using established protocols. The presence or absence of digital vasospasm following cooling was determined by finger systolic pressure measurements using laser Doppler flowmetry. The test protocols used have been evaluated in patients with a clear clinical diagnosis of non-occupational Raynaud's syndrome.

RESULTS

6.3% of the riveters and 83.5% of the claimants reported specific Raynaud's syndrome symptoms but 30.4% of the riveters and only 19% of the claimants tested positive for vasospasm after middle phalangeal cooling to 10 degrees C for 5 min. Using a more severe cooling protocol provoked vasospasm in 46.8% of the claimants. Lack of sensitivity or specificity of the objective testing could not explain the large discrepancies between the findings in the riveters and in the claimants.

CONCLUSIONS

Questionnaire responses concerning VWF symptoms can be influenced by the context in which they are recorded. It is important to employ more objective methods in assessing all workers at risk of developing VWF.

Acute effects of vibration on peripheral blood flow in healthy subjects

OBJECTIVES

The main objective was to study the acute vascular effects in the hands of normal healthy subjects of a complex vibration spectrum similar to that generated by many industrial hand held tools. The effects of repeated bouts of vibrations and alterations in the intensity of vibration were also studied.

METHODS

Blood flow was measured by venous occlusion plethysmography with strain gauges. Vibration across a frequency range of 0.4 to > 4000 Hz was generated by a pneumatic chisel and applied to the right hand. Blood flow was measured in both middle fingers, both big toes, or both forearms before, during, and after a two minute period of vibration. Systolic pressure of a finger and heart rate were also measured.

RESULTS

Vibration was associated with a significant bilateral reduction in finger and toe blood flow (P < 0.01 and P < 0.03) and a significant increase in heart rate (P < 0.05) but had no effect on forearm blood flow. The finger response was not abolished by repeated bouts of the vibration but was initially most notable during the first minute of vibration. Increasing the intensity of vibration delayed recovery.

CONCLUSIONS

Hand vibration causes a generalised increase in sympathetic tone in the heart and extremities. This may be a factor in the development of vasospastic disease in habitual users of hand held industrial vibrating tools.

Small or absent fetal stomach: prognostic significance

PURPOSE

To investigate the outcome of fetuses with a small or absent stomach.

MATERIALS AND METHODS

We retrospectively reviewed sonograms in 87 fetuses with a small or absent stomach. Gestational age, amniotic fluid volume, stomach size, morphologic defects, and karyotypes were correlated with clinical follow-up or autopsy findings.

RESULTS

Eight pregnancies were excluded because of oligohydramnios due to ruptured membranes. Seventy-nine fetuses with an absent (n = 27) or small (n = 52) stomach were included in the study group. Gestational ages ranged from 18 to 39 weeks (mean, 27 weeks). An abnormal outcome (structural abnormalities, intrauterine fetal or postnatal death) occurred in 23 (85%) of 27 fetuses with an absent stomach and 27 (52%) of 52 fetuses with a small stomach (combined, 63%). Karyotype was abnormal in eight (38%) of 21 fetuses with an absent stomach and two (4%) of 46 fetuses with a small stomach.

CONCLUSION

An absent or small fetal stomach after 18 weeks gestation is associated with a guarded prognosis.

Prenatal diagnosis of esophageal atresia

The prenatal sonographic detection of esophageal atresia (EA) has been possible for more than a decade and relies on the finding of a small or absent fetal stomach bubble associated with maternal polyhydramnios. The aims of this study were to assess the accuracy of this technique and to determine whether the outcome of prenatally diagnosed EA differs from its postnatal counterpart. All fetal sonograms performed between January 1989 and October 1993 demonstrating a small or absent fetal gastric bubble were reviewed together with all neonates with EA treated during the same period. Eighty-seven fetuses with a small (n = 53) or absent stomach bubble (n = 34) were identified, representing 1.4% of all fetal sonographic surveys. Esophageal atresia was present in 15; in 13 of these, the maternal amniotic fluid volume was increased. The positive predictive value of an absent stomach bubble and polyhydramnios was 56%, and the sensitivity of prenatal sonography in the diagnosis of EA was 42%. One neonate with EA had the prenatal diagnosis established at another institution, yielding a total of 16 cases of prenatally diagnosed EA for analysis. Seven (44%) of these had trisomy 18. Of the remaining nine, two had isolated EA, two had laryngeal atresia and EA, and there were two late-gestational unexplained fetal deaths. Only four (25%) survived through the neonatal period. The prognosis of the fetus with EA is radically different from that of the neonate with EA.

The empty amnion: a sign of early pregnancy failure

Between 6.5 to 10 weeks of gestation, the length of the amniotic cavity is similar to that of the embryo. It follows that by the time an amniotic sac is detectable sonographically, an embryo of equal length should also be visualized. Retrospective review of case records at our institution revealed 15 patients in whom the amnion was visualized in the absence of an embryonic pole during first trimester sonography (endovaginal and transvesical). Indications for sonographic examination included gestational age estimation, discrepant size and dates, or vaginal bleeding. The mean sac diameter for the 15 gestations ranged from 14 to 36 mm, corresponding to gestational ages of 6.1 to 9.5 weeks. Ages based on the last menstrual period ranged from 6.1 to 11 weeks. A yolk sac was identified in all cases in addition to the amniotic sac, but neither an embryo nor cardiac pulsations were observed. In 12 of the 15 cases the size of the gestational sac was greater than 16 mm, such that the absence of an embryo also met an accepted criterion for a failed pregnancy. Follow-up in all cases confirmed early pregnancy failure. In this series the demonstration of an "empty amnion" (visualization of an amnion but no identifiable embryonic pole) was always associated with pregnancy loss. The "empty amnion" sign is helpful as an additional finding confirming early pregnancy failure.

Vascular responses in chain saw operators

The intensive use of chain saws is associated with development of the hand-arm vibration syndrome (vibration white finger). Objective testing for cold induced vasospasm was carried out on the fingers of 12 chain saw operators and 12 matched control men from a similar working environment. Two of the chain saw operators tested positive for vasospasm in the laboratory and another three had an abnormal result. All of the control subjects tested negative. Measurements of finger blood flow at different temperatures and during vibration of the hand were similar in the chain saw operators and controls. Use of the chain saw did not cause significant alterations in the plasma concentrations of von Willebrand factor antigen in either the long or the short term.

An investigation into the acute vascular effects of riveting

Measurements were made on 46 pairs of riveters and matched control subjects before and after a morning's work. Before starting work, the mean resting finger systolic pressure was 112 (SEM 3.3) mm Hg in the riveters, similar to 117 (1.7) in the control subjects. After cooling the middle phalanx to 10 degrees C for five minutes, 16 riveters but only one control subject exhibited digital vasospasm and these numbers were unaltered after a morning's work. A subgroup of riveters whose role was always to provide counter pressure to the rivet gun showed a higher incidence (45%) of cold induced vasospasm than did riveters who invariably held the gun (10%) or rotated between both roles (27%). Plasma levels of three markers of vascular activity, endothelin-1 (ET-1), von Willebrand factor antigen (vWFAg), and angiotensin converting enzyme (ACE), were measured in non-smoking riveters and control subjects. Before work, ET-1 concentrations were slightly lower (p < 0.05) in the riveters, but vWFAg concentration and ACE activity were similar in riveters and control subjects. Riveting for a morning did not alter ET-1 concentration or ACE activity but did induce a small increase (p < 0.05) in vWFAg concentration, which may indicate damage to the endothelium. This type of vascular assessment may be helpful in assessing vasospastic complications in workers exposed to vibration.

Hirsutism in a gynaecological context

Investigation of patients presenting with hirsutism to a gynaecological endocrine clinic revealed a high incidence of anovulation, obesity and elevated androgen levels. The underlying abnormality was polycystic ovarian syndrome (PCOS) in the majority of patients. Low levels of sex hormone binding globulin were common; these increased with oestrogen treatment. Treatment with a combined oral contraceptive pill and low dose spironolactone was often effective in reducing symptoms.

Combined treatment with gonadotrophin releasing hormone agonist and gonadotrophins in poor responders to hyperstimulation for in vitro fertilization (IVF): clinical and endocrine results

Seventy three cycles of combined gonadotrophin releasing hormone (GnRH) agonist/gonadotrophin treatment for IVF controlled ovarian hyperstimulation in previous poor responders to standard ovarian hyperstimulation therapy are reported. Oocyte numbers obtained were better than the previous average results, but were similar to the previous best response. In general more oocytes than the previous mean could be expected but low order responders were not transformed into high order responders. Pregnancies did occur in this difficult group of patients but the rate was modest. Because of a reduction in cancelled cycles, patients might reduce their total costs in time and gonadotrophin used, however this treatment is not a panacea for the true low order responder.

Clomiphene citrate and ovarian resistance

An uncommon association between clomiphene citrate and the development of ovarian resistance to gonadotrophins is described. We advise against the use of clomiphene in the rare patient with the resistant ovary syndrome, and advise caution in any patient who exhibits a decreasing oestrogen response to clomiphene ovulation induction.

The fate of supernumerary oocytes in gamete intrafallopian transfer (GIFT) is not predictive of a poor outcome: the effect of oocyte selection

In 161 consecutive gamete intrafallopian transfer (GIFT) cycles in which supernumerary oocytes were inseminated, a failure to fertilize any of these oocytes was no more predictive of an unsuccessful outcome than the simple overall pregnancy rate in this group. This is possibly related to the significantly reduced proportion of oocytes graded as good in the supernumerary group.

Anti-oestrogens: their clinical physiology and use in reproductive medicine

The anti-oestrogens are important both as therapeutic agents in reproductive medicine and as tools to investigate the physiology of the oestrogen receptor and hormonal control mechanisms. Clomiphene occupies the oestradiol receptor and, although initially stimulatory, has a net antagonistic effect as oestrogen receptors are not replenished. The major fertility-enhancing effect is to cause an increase in LH and FSH output by increasing the frequency of pulsatile output of these hormones. Many effects due to an anti-oestrogenic effect have been postulated; some, such as an adverse effect on cervical mucus, have been proven. The clinical use of the anti-oestrogens is outlined in Table 1. In well chosen patients a rewarding pregnancy rate is obtained with minimal intervention and few important side-effects. The challenge for the reproductive biologist is successfully to manage the patient who is clomiphene-resistant, either because of failure to ovulate or failure to conceive once ovulation is induced.

Approaches to MR angiography

One of the most revolutionary recent imaging advances is the use of magnetic resonance to study and produce morphologic representations of flowing blood vessels known as MR angiography. The ability to produce an image of even moderate spatial resolution of the three dimensional course of blood vessels with MR could have significant advantages over conventional invasive angiography which requires ionizing radiation and contrast material injection. By definition, MR angiography does not require the addition of any intravascular contrast agents and the images are produced entirely by the effect of the radio frequency pulses and magnetic field gradients on the spinning protons. Several researchers are already producing relatively high resolution MR angiograms using a variety of techniques. Essentially all techniques of MR angiography use variations of three steps to produce the image: (1) a projection image, (2) suppression of background static material, and (3) production of a flow sensitive image. This report will survey some of the more commonly used approaches to MR angiography that are currently under investigation.