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Exosomes are cell-derived nanovesicles involved in regulating intercellular communications. In contrast to conventional nanomedicines, exosomes are characterized by unique advantages for therapeutic development. Despite their major successes in drug delivery, the full potential of exosomes for immunotherapy remains untapped. Herein we designed genetically engineered exosomes featured with surfaced-displayed antibody targeting groups and immunomodulatory proteins. Through genetic fusions with exosomal membrane proteins, Expi293F cell-derived exosomes were armed with monoclonal antibodies specific for human T-cell CD3 and epidermal growth factor receptor (EGFR) as well as immune checkpoint modulators, programmed death 1 (PD-1) and OX40 ligand (OX40L). The resulting genetically engineered multifunctional immune-modulating exosomes (GEMINI-Exos) can not only redirect and activate T cells toward killing EGFR-positive triple negative breast cancer (TNBC) cells but also elicit robust anti-cancer immunity, giving rise to highly potent inhibition against established TNBC tumors in mice. GEMINI-Exos represent candidate agents for immunotherapy and may offer a general strategy for generating exosome-based immunotherapeutics with desired functions and properties.

Background: The cytokine interleukin 2 (IL-2) is involved in the activation of T cells and has been shown to play a central role in cancer immunotherapy. The full therapeutic potential of IL-2, however, has not been realized because of its dose-limiting systemic toxicity. We sought to identify a region of IL-2 that is responsible for the induction of vasopermeability (leaky tumor endothelium), a property associated with the toxicity of the molecule. Methods: Intact IL-2 or overlapping synthetic peptides of IL-2 that were chemically conjugated to tumor-targeting monoclonal antibodies (TNT-1 or Lym-1) were injected into groups of mice (n = 4) that had previously been xenotransplanted with human tumor cells (ME-180 cervical carcinoma and Raji lymphoma). Two hours later, mice received intravenous injections of radiolabeled tracer antibody, and 3 days later they were subjected to biodistribution analysis to measure the ability of each immunoconjugate to enhance tumor uptake of the tracer antibody (i.e., vasopermeability activity). The cytokine activity of the immunoconjugates was determined by assaying their ability to promote the proliferation of a mouse IL-2-dependent cell line. Results: Pretreatment of mice with an antibody/IL-2 immunoconjugate resulted in an approximately fourfold increase in radiolabeled tracer antibody uptake in the xenograft tumor as compared with uptake in mice injected with antibody alone. One synthetic fragment consisting of amino acids 22-58 contained 100% of the vasopermeability activity of IL-2 and was designated permeability-enhancing peptide (PEP). PEP had vasopermeability activity only when conjugated to a tumor-targeting antibody, had maximal activity as a dimer, and was devoid of cytokine activity. Conclusions: The identification of PEP should aid in the discovery of ways to decrease the toxicity of IL-2. Moreover, PEP is a promising candidate for the generation of agents that can enhance the delivery of antibodies and drugs to tumors.

Tumor-associated macrophages (TAMs) are often the most abundant immune cells in the tumor microenvironment (TME). Strategies targeting TAMs to enable tumor cell killing through cellular phagocytosis have emerged as promising cancer immunotherapy. Although several phagocytosis checkpoints have been identified, the desired efficacy has not yet been achieved by blocking such checkpoints in preclinical models or clinical trials. Here, we showed that late-stage non-Hodgkin lymphoma (NHL) was resistant to therapy targeting phagocytosis checkpoint CD47 due to the compromised capacity of TAMs to phagocytose lymphoma cells. Via a high-throughput screening of the US Food and Drug Administration–approved anticancer small molecule compounds, we identified paclitaxel as a potentiator that promoted the clearance of lymphoma by directly evoking phagocytic capability of macrophages, independently of paclitaxel’s chemotherapeutic cytotoxicity toward NHL cells. A combination with paclitaxel dramatically enhanced the anticancer efficacy of CD47-targeted therapy toward late-stage NHL. Analysis of TME by single-cell RNA sequencing identified paclitaxel-induced TAM populations with an upregulation of genes for tyrosine kinase signaling. The activation of Src family tyrosine kinases signaling in macrophages by paclitaxel promoted phagocytosis against NHL cells. In addition, we identified a role of paclitaxel in modifying the TME by preventing the accumulation of a TAM subpopulation that was only present in late-stage lymphoma resistant to CD47-targeted therapy. Our findings identify a novel and effective strategy for NHL treatment by remodeling TME to enable the tumoricidal roles of TAMs. Furthermore, we characterize TAM subgroups that determine the efficiency of lymphoma phagocytosis in the TME and can be potential therapeutic targets to unleash the antitumor activities of macrophages.

Background. To enhance monoclonal antibody uptake in tumors, seven novel vasoactive immunoconjugates were developed that selectively alter the vascular permeability and/or blood volume of tumors in vivo. These immunoconjugates, composed of IL-1[beta], IL-2, TNF-[alpha], physalaemin, leukotriene [B.sub.4], histamine, and bradykinin chemically linked to TNT-1, a murine monoclonal antibody that binds necrotic regions in tumors, have been tested for their effects on antibody uptake in vivo. Methods. Groups of four mice, each bearing the ME-180 human cervical carcinoma, were pretreated either 3 or 24 hours before the administration of 1-125 labeled TNT-1 F([ab').sub.2], fragment. Three-day biodistribution studies then were performed to determine the amount of radiolabeled antibody in the tumors and normal organs of the mice. In addition, mechanism of action studies were performed to determine if the vasoactive immunoconjugate affected the vascular permeability or blood volume of the tumor vessels. Results. TNT-1/IL-2 gave the highest percent injected dose/g in tumor (4.80), compared with TNT-1/TNF (4.00), TNT-1/IL-L (3.83), TNT-1/leukotriene-[B.sub.4] (2.84), TNT-1/histamine (2.80), TNT-1/physalaemin (2.19), TNT-1/bradykinin (1.57), or TNT-1 alone (1.28). All of these immunoconjugates showed specific enhancement of monoclonal antibody uptake in tumor with no changes seen in normal tissues. Quantitative studies that demonstrated the mechanism of action of these immunoconjugates showed that TNT-1/IL-2 and TNT-1/histamine produced a marked change in the vasopermeability of tumor vessels but had no effect on tumor blood volume. In contrast, TNT-1/IL-1 and TNT-1/TNF produced a combination of effects, and TNT-1/leukotriene [B.sub.4] TNT-1/bradykinin, and TNT-1/physalaemin affected only tumor blood volume. Conclusions. These studies indicate that pretreatment with vasoactive immunoconjugates may improve monoclonal antibody uptake in tumors significantly and thereby increase the therapeutic index of monoclonal antibody-directed immunotherapy.

Flow cytometry is a laboratory technique that is receiving increasing attention as a potential method for improving the accuracy of prognosis for cancer. The device, a flow cytometer, dribbles cells past a sophisticated laser and optical system which makes measurements on a large number of cells one at a time. Most researchers have used this technique to measure the DNA content of the cells from a specimen. However, the same method may be used to measure any cellular component for which a fluorescent indicator is available. Researchers have now applied this technique to the measurement of p105, a protein found in the nuclei of cells which is correlated with proliferative activity. That is, p105 is found in the nuclei of cells which are multiplying, but not in quiescent cells. A study was conducted to evaluate the presence or absence of p105 in a sample of 114 advanced stomach cancers. Flow cytometry can measure several substances simultaneously, and this capability was used in the present study to measure DNA as well as p105. Using specific antibodies which bind to p105, it was found that from 9.3 to 79 percent of the cells in various specimens contained p105. A greater fraction of cells containing p105 was found among cancers with abnormal amounts of DNA (aneuploid), cancers that had spread to the liver, cancers that had invaded blood vessels, and cancers having the appearance of well differentiated cells under the microscope. In cases where more than 30 percent of the cells contained p105, there was a 22 percent five-year survival rate. For the patients with fewer than 30 percent of cells containing p105, the survival rate was 66 percent. Statistical analysis revealed that the fraction of cells containing p105 was an independent prognostic indicator, which added prognostic information to that obtained from other prognostic factors such as DNA content, blood vessel invasion, and the stage of the stomach cancer. The results suggest that measurement of p105 in stomach cancer specimens may provide useful prognostic information. (Consumer Summary produced by Reliance Medical Information, Inc.)

Exosomes are nanosized membranous vesicles secreted by a variety of cells. Due to their unique and pharmacologically important properties, cell-derived exosome nanoparticles have drawn significant interest for drug development. By genetically modifying exosomes with two distinct types of surface-displayed monoclonal antibodies, we have developed an exosome platform termed synthetic multivalent antibodies retargeted exosome (SMART-Exo) for controlling cellular immunity. Here, we apply this approach to human epidermal growth factor receptor 2 (HER2)-expressing breast cancer by engineering exosomes through genetic display of both anti-human CD3 and anti-human HER2 antibodies, resulting in SMART-Exos dually targeting T cell CD3 and breast cancer-associated HER2 receptors. By redirecting and activating cytotoxic T cells toward attacking HER2-expressing breast cancer cells, the designed SMART-Exos exhibited highly potent and specific anti-tumor activity both in vitroand in vivo. This work demonstrates preclinical feasibility of utilizing endogenous exosomes for targeted breast cancer immunotherapy and the SMART-Exos as a broadly applicable platform technology for the development of next-generation immuno-nanomedicines.

The identification and use of antibodies dominate the biologic, clinical diagnostic, and therapeutic landscapes. In particular, antibodies have become essential tools in a variety of protein analytical experiments and to study the disposition of biologic therapeutics. One emerging class of peptide biologics is known as the elastin-like polypeptides (ELPs), which are repetitive protein polymers inspired by human tropoelastin. A major limitation in the clinical translation of ELP biologics has been a lack of a monoclonal antibody (mAb) to characterize their identity during expression. To facilitate these studies, we successfully generated a new mAb that is specific toward ELPs and ELP fusion proteins. A purified antibody was evaluated in an ELISA, western blotting, and immunofluorescence assay. The optimal anti-ELP mAb proved to be highly reactive and specific toward ELPs. Moreover, they were able to detect ELPs with a variety of aliphatic guest residues. ELPs phase-separate in response to heating; furthermore, when incubated at a great excess of ELPs, the anti-ELP mAb partially blocks phase separation. These findings are direct evidence that novel murine mAbs can be raised against purified ELPs. This new reagent will enable purification, experimental detection, and characterization of these biopolymers.

The first silicone breast implant was inserted in 1962. In 1997, the first case of anaplastic large cell lymphoma (ALCL) in association with a silicone breast implant was reported. The authors reviewed 37 articles in the world literature reporting on 79 patients and collected another 94 unreported cases as of the date of submission.

B-cell lymphomas continue to occur with a high incidence. The chimeric antibody known as Rituximab (Rituxan) has become a vital therapy for these patients. Rituximab induces cell death viabinding and clustering of the CD20 receptor by Fcγ expressing effector cells. Because of the limited mobility of effector cells, it may be advantageous to cluster CD20 directly using multivalent nanostructures. To explore this strategy, this manuscript introduces a nanoparticle that assembles from a fusion between a single chain antibody and a soluble protein polymer. These hybrid proteins express in Escherichia coliand do not require bioconjugation between the antibody and a substrate. Surprisingly a fusion between an anti-CD20 single chain antibody and a soluble protein polymer assemble worm-like nanostructures, which were characterized using light scattering and cryogenic transmission electron microscopy. These nanoworms competitively bind CD20 on two B-cell lymphoma cell lines, exhibit concentration-dependent induction of apoptosis, and induce apoptosis better than Rituximab alone. Similar activity was observed in vivousing a non-Hodgkin lymphoma xenograft model. In comparison to Rituximab, systemic nanoworms significantly slowed tumor growth. These findings suggest that hybrid nanoworms targeted at CD20 may be useful treatments for B-cell related malignancies. Because of the ubiquity of antibody therapeutics, related nanoworms may have uses against other molecular targets.

Murine monoclonal antibody (mAb) Lym‐1 is an immunoglobulin G2a specific for certain human leukocyte antigen‐DR variants expressed on the surface of malignant B cells. It has been proposed for serotherapy in patients with B lymphomas. We have previously shown thatmAb Lym‐1 synergizes with granulocyte macrophage‐colony stimulating factor to promote Raji B‐lymphoid cell lysis by human neutrophils via the intervention of neutrophil Fc receptors type II and D‐mannose‐inhibitable interactions between CD11b–CD18 integrins and CD66b glycoproteins. Here, we provide evidence that the process is oxygen‐independent by inference related to the release of primary granules and is regulated by cathepsin G activity. The lysis was indeed reproduced by replacing normal neutrophils with cells from three patients suffering from chronic granulomatous disease, i.e., neutrophils genetically incapable of generating oxidants. Moreover, the lysis was inhibited by the serine protease inhibitor 3,4‐dichloroisocoumarin and by Z‐glycyl‐leucyl‐phenyl‐chloromethyl ketone (Z‐Gly‐Leu‐Phe‐CMK), which blocks cathepsin G. Conversely, the lysis was unaffected by N‐methoxysuccinyl‐alanyl‐alanyl‐prolyl‐alanyl‐CMK (MeOSuc‐Ala‐Ala‐Pro‐Ala‐CMK; elastase inhibitor) and MeOSuc‐Ala‐Ala‐Pro‐valine (Val)‐CMK, which inhibits elastase and proteinase 3. The ability of neutrophils, engaged in cytolysis, to release cathepsin G was proved by detecting this enzymatic activity spectrophotometrically and immunocytochemically. Moreover, inhibition of cathepsin G activity by concentrations of Z‐Gly‐Leu‐Phe‐CMK, incapable of affecting elastase activity, was found to reduce the release of elastase and myeloperoxidase from neutrophils under conditions similar to those used for cytolytic assays. These findings suggest that neutrophils auto‐regulate their lytic efficiency by controlling the exocytosis of primary granules via their cathepsin G activity.

Because of its key role in immunity, interleukin-2 (IL-2) has been studied extensively for the adoptive immunotherapy of cancer. Although systemic administration of IL-2 has been shown to stimulate antitumor responses in vivo, its efficacy in the clinic has been limited by the development of serious side effects, including the induction of vascular leak syndrome. Previously, we have identified a small peptide fragment of IL-2 that was found to contain the entire vasopermeability activity of the cytokine. The identification of the location of this potentially undesirable property of IL-2 enabled us to focus on the generation of mutant derivatives that might be lacking vasopermeability activity but that retain cytokine functionality. In addition to this discovery, our laboratory has constructed monoclonal antibody/IL-2 fusion proteins that can target this potent cytokine directly to tumor for the immunotherapy of both solid and lymphoid malignancies. Using this fusion protein technology, we have constructed a series of point mutations in the newly identified vasopermeability region of IL-2 for the purpose of deleting this activity. Fusion proteins showing reduced or deleted vasopermeability activity were then tested for their cytokine potency by several methods, including their binding to IL-2 receptors, T-cell proliferation assays, the induction of secondary cytokines, dose-escalating toxicity, and finally their ability to treat established solid tumors in syngeneic immunocompetent mice. The results of these studies clearly show that the vasopermeability activity of IL-2 can be substantially deleted by single point mutations such as Arg38Trp without grossly affecting the immune function of the cytokine.

Although intact monoclonal antibodies (MAbs) are well suited as therapeutic reagents, their relatively slow clearance rates render them less useful for imaging applications. Over the last several years, our laboratory has developed a unique targeting approach to solid tumors that utilizes MAbs directed against DNA and its components to bind to degenerating cells and necrotic regions of tumors in a specific manner. Because these MAbs have considerable potential for the early diagnosis of cancer and for the monitoring of cytoreductive therapies, the availability of an effective imaging agent is highly desirable. To accomplish this goal, a series of genetically engineered derivatives of MAb chTNT-3 including the single-chain Fv, diabody, triabody, Fab, and F(ab′)2 were generated and expressed in NS0 myeloma cells using the Glutamine Synthetase Amplification System. Initial in vitro studies demonstrated that each of the antibody derivatives maintained its antigen binding in a stable manner. In vivo analyses after radiolabeling were then performed to evaluate their pharmacokinetic, biodistribution, and tumor-imaging properties in solid tumor-bearing mice. The results of these studies showed that compared with intact parental chTNT-3, which has a half-life of 134.2 h, the smaller derivatives were eliminated more rapidly (4.9-8.1 h). Importantly, the smaller derivatives were found to have significantly higher tumor-to-organ ratios, but lower overall uptake levels compared with parental 125I-chTNT-3 in two different tumor models. A comparison of the five derivatives showed that the F(ab′)2 reagent consistently gave the best results in imaging and biodistribution studies. Based upon these results, further studies are warranted to demonstrate the potential of this reagent for the diagnosis and monitoring of solid tumors using noninvasive imaging techniques such as immunoscintigraphy and positron emission tomography (PET).

Studies have shown that cytokines can effectively treat solid tumors by a direct cytotoxic effect as well as by immunomodulation. Both human interferon gamma (IFNγ) and tumor necrosis factor alpha (TNFα) have been used to treat a variety of colon carcinoma cell lines and tumors in patients. These cytokines, however, are dose limited by their toxicity and fast clearance rates when given intravenously. To improve their therapeutic value, we now report on the generation of two new fusion proteins consisting of human IFNγ and TNFα genetically linked to the C-terminal portion of chTNT-3, a monoclonal antibody (MAb), which targets human solid tumors by binding to intracellular antigens exposed in degenerating cells associated with tumor necrosis. In vitro characterization studies demonstrate that both the IFNγ and TNFα fusion proteins are able to maintain their binding affinity to antigen as well as their direct cytotoxic effect and immunomodulatory functions. When both fusion proteins are combined at optimal doses, they demonstrate a 30% direct cellular cytotoxicity of human colon carcinoma cells of which approximately 14% can be attributed to apoptosis. In vivo, these agents were studied for their pharmakocinetic clearance rates and their ability to target human colon carcinomas heterotransplanted in nude mice. The results of these studies show that, compared with chTNT-3 parental antibody, both fusion proteins have a substantially shorter whole body half-life, yet are able to target tumor in a similar manner. As each of these fusion proteins are cleared from the circulation and normal tissues, tumor-to-normal-tissues ratios rise demonstrating the retention of these reagents in tumor. The generation of long-acting and targeted human IFNγ and TNFα antibody fusion proteins will enable investigators to study the role of these potent immunostimulatory cytokines in the treatment of human solid tumors.

To improve the clinical potential of monoclonal antibodies (MAbs), new methods are required to augment antibody uptake in the tumor while minimizing binding in normal tissues. Our laboratory has pioneered the use of chemical modification to accomplish this goal. Using three chimeric MAbs, chTNT-1, chTNT-2, and chTNT-3, which target solid tumors by binding to common antigens found in the central necrotic core, we now demonstrate the potential of chemical modification to improve the pharmacokinetic characteristics of these unique MAbs. To identify optimal modification conditions, TNT MAbs were reacted with biotin at various ratios and tested by clearance and biodistribution analyses. The biodistribution results revealed that the numbers of biotin molecules per MAb yielding optimal tumor uptake were 3:1 for chTNT-1, 5:1 for chTNT-2, and 8:1 for chTNT-3. Biotinylated MAbs were found to have faster whole body clearance times and better biodistribution profiles compared to unmodified antibodies. Although chTNT-2 showed only a modest improvement after biotinylation, biodistribution results indicated that this MAb had the highest uptake in tumor. By reducing the charge of the antibody molecule, chemical modification appears to be a useful method for improving the pharmacokinetics and biodistribution of TNT antibodies directed to the necrotic region of solid tumors.

F(ab′)2 fragments are desirable structural derivatives of monoclonal antibodies (MAbs) because of their pharmacokinetic properties and bivalent binding to antigen. Production of these fragments, however, has proven difficult because of the variable sensitivity of intact antibodies to proteolytic enzymes, which can result in very low yields and unstable product. To circumvent these problems, we attempted to apply genetic engineering methods to generate stable F(ab′)2 fragments in NSO murine myeloma cells using the glutamine synthase expression system. For these studies, the chimeric MAb, chTNT-3, directed against necrotic regions of solid tumors, was used to generate several F(ab′)2 variants, which contained between one and three cysteine residues at the end of the hinge region. In addition, two different affinity tags (his tag, streptactin tag) were used with each variant to determine the best tag for purification procedures. Stability was measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and by antigen binding studies and the constructs were tested in vivo to measure their pharmacokinetic properties and biodistribution in normal organs and tumor. The results of these studies show that 3 cysteine residues are required to produce stable F(ab′)2 fragments and that either purification tag can be used with this variant to produce suitable reagents for in vivo studies. Those constructs containing one or two cysteines were found to be unstable and broke down to Fab fragments regardless of the purification tag used. These studies demonstrate that stable, clinically useful F(ab′)2 fragments of chTNT-3 can be produced in mammalian cells by genetic engineering methods.

To eliminate the human anti-mouse antibody (HAMA) response seen in patients treated with murine and chimeric antibodies, fully human monoclonal antibodies (MAbs) are now being developed. Tumor Necrosis Therapy (TNT) is an approach to tumor targeting that utilizes MAbs directed against common intracellular antigens such as nucleic acids, accessible only in necrotic areas of solid tumors. By binding to the necrotic core of tumors, these TNT MAbs can circumvent many of the limitations of MAbs directed against tumor cell surface antigens. Chimeric TNT-1 (chTNT-1) was first developed from the parent murine antibody by genetically engineering the murine variable regions to the human IgG₁ and kappa constant regions. Although the chimeric antibody's behavior was similar to that of the murine version, the 35% murine homology it shares allows for the potential of a HAMA response. A human antibody derived from a phage display library, designated NHS76, has been developed with similar binding characteristics to the TNT-1. To demonstrate that this genetically engineered human counterpart to chTNT-1 has similar pharmacokinetic characteristics, in vivo behavior, and targeting abilities, both antibodies were rigorously tested in parallel. For these studies, biodistribution analysis in LS174T human colon tumor-bearing nude mice was performed to compare the uptake levels in tumor and normal organs. In addition, mouse imaging and autoradiographic studies were conducted to demonstrate positive uptake in necrotic regions of tumor and negative uptake in viable tissues and organs. The results of these studies confirm the comparable nature of both antibodies and provide the necessary preclinical data to show the suitability of NHS76 as an improved product for the therapy of solid tumors in man.

Human neutrophils incubated with the anti‐HLA‐DR mAb Lym‐1, plus PMA, induced significant cytolysis of B lymphoma cells compared with Lym‐1 and PMA alone. The effect of PMA was independent of the ability of the compound to stimulate neutrophil‐respiratory burst. In fact, first, neutrophils from a patient with chronic granulomatous disease were cytolytically effective in spite of their inability to produce oxidants. Second, various kinase inhibitors exerted different effects on the PMA‐stimulated cytolytic system and neutrophil‐oxidative burst. Previous studies have shown the involvement of the FcγRII, CD11b‐CD18 integrins, and CD66b glycoproteins in the Lym‐1 mAb‐dependent cytolysis by GM‐CSF‐stimulated neutrophils. The present PMA‐stimulated system was inhibited by the anti‐FcγRII mAb IV.3, the anti‐CD18 mAb MEM 48, and the anti‐CD11b mAb 2LPM19c but not by the anti‐CD66b mAb 80H3 andN‐acetyl‐d‐glucosamine. Furthermore, the PMA‐ and GM‐CSF‐stimulated cytolysis was insensitive and sensitive to inhibition by pertussis toxin, respectively. Thus, the use of PMA and GM‐CSF as neutrophil stimulants uncovers the existence of distinct mechanisms of Lym‐1 mAb‐mediated cytolysis.

Contortrostatin is a unique dimeric disintegrin isolated from southern copperhead snake venom. Through antagonism of integrins αIIbβ3, α5β1, αvβ3, and αvβ5, contortrostatin inhibits platelet aggregation and disrupts cancer cell adhesion and invasion. We cloned cDNA from a library made from the venom gland cells of Agkistrodon contortrix contortrix using polymerase chain reaction. We found that the contortrostatin gene is part of a precursor composed of proprotein, metalloproteinase, and disintegrin domains. The precursor cDNA is 2027 bp with a 1449-bp open reading frame. The disintegrin domain is 195 bp encoding 65 amino acids. Like other members of the disintegrin family, each subunit of contortrostatin has an RGD site, and the cysteine alignment is conserved. The disintegrin domain of the cDNA has been expressed in a eukaryotic expression system as a homodimeric fusion protein with an immunoglobulin. The recombinant protein is recognized by an antiserum against native contortrostatin in Western blot. Both the native and recombinant proteins bind to integrins αvβ3 and αvβ5. Like native contortrostatin, the recombinant fusion protein inhibits platelet aggregation, blocks cancer cell adhesion to fibronectin and vitronectin, and prevents invasion of cancer cells through a Matrigel barrier. The success of functional expression not only validates the cDNA cloning of this disintegrin, but also provides adequate material for functional studies of contortrostatin.

Tumor-associated macrophages (TAMs) are often the most abundant immune cells in the tumor microenvironment (TME). Strategies targeting TAMs to enable tumor cell killing through cellular phagocytosis have emerged as promising cancer immunotherapy. While several phagocytosis checkpoints have been identified, the desired efficacy has not yet been achieved by blocking such checkpoints in preclinical models or clinical trials. Here, we showed that late-stage Non-Hodgkin's Lymphoma (NHL) was resistant to therapy targeting phagocytosis checkpoint CD47, due to the compromised capacity of TAMs to phagocytose lymphoma cells. Via a high-throughput screening of FDA-approved anti-cancer small molecule compounds, we identified paclitaxel as a potentiator that promotes the clearance of lymphoma by directly evoking phagocytic capability of macrophages, independently of paclitaxel's chemotherapeutic cytotoxicity toward cancer cells. A combination with paclitaxel dramatically enhanced the anti-cancer efficacy of CD47-targeted therapy toward late-stage NHL. Analysis of TME by single-cell RNA sequencing identified paclitaxel-induced TAM populations with an upregulation of genes for tyrosine kinase signaling. The activation of Src family tyrosine kinases (SFK) signaling in macrophages by paclitaxel promoted phagocytosis against NHL cells. In addition, we identified a role of paclitaxel in modifying the TME by preventing the accumulation of a TAM subpopulation that is only present in late-stage lymphoma resistant to CD47-targeted therapy. Our findings identify a novel and effective strategy for NHL treatment, by remodeling TME to enable the tumoricidal roles of TAMs. Furthermore, we characterize TAM subgroups that determine the efficiency of lymphoma phagocytosis in the TME and can be potential therapeutic targets to unleash theanti-tumor activities of macrophages.

An experimental kidney infarction model was developed in the mouse to study the uptake of a radiolabeled monoclonal antibody previously shown to bind to degenerating cells in malignant tumors. To determine if this approach is applicable to normal tissue and cell degeneration, kidney infarction was produced by clamping the mouse renal artery for 3 h using surgical procedures. Various groups of mice were injected with 131I‐labeled TNT‐1 F(ab‘)2monoclonal antibody directed against nuclear histone antigens at varying intervals after surgery. Imaging, biodistribution, autoradiography, and histological studies were performed on each group of mice, including sham‐operated controls, to quantitate the level of binding and localize the uptake of label in clamped and unclamped (contralateral) kidneys. As additional controls, clamped mice were administered radiolabeled irrelevant monoclonal antibody Lym‐1 or mouse albumin. The results showed a marked selective uptake of radiolabeled TNT‐1 F(ab‘)2in the injured clamped kidney compared with the untreated kidney and other normal organs of the mouse. These studies define a model of normal organ necrosis that may be useful for study of the kinetics of antibody uptake in infarcted tissues.— Chen, F.‐M.; Wisner, J. R., Jr.; Omachi, H.; Renner, I. G.; Taylor, C. R.; Epstein, A. L. Localization of monoclonal antibody TNT‐1 in experimental kidney infarction of the mouse. FASEB J.4: 3033‐3039; 1990.

Summary Radiolabeled murine monoclonal antibody TNT-1, directed against the nuclear histones of degenerating cells, was used to treat human colon adenocarcinoma HT-29 spheroids in vitro. The therapeutic effects of131I-TNT-1 were investigated as a function of the radioactive dose, treatment time, and number of treatments. Efficacy of treatment was assessed by TNT-1 antibody uptake, spheroid growth delay, and morphological examination using light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). From these studies, it was determined that the therapeutic effect increased with the number of doses and the duration of treatment. Spheroids treated for 24 h showed approximately two to four times more cell death than those with a 2-h treatment. As previously shown in animal models, additonal treatment with radiolabeled TNT-1 produced an expanding number of TNT-1 targets, and subsequent treatments were more effective as shown by antibody uptake studies. Microscopic examinations demonstrated that morphological changes consistent with spheroid destruction correlated well with antibody uptake data and increased gradually with dose, treatment time, and frequency of treatments. At the ultrastructural level, destruction of cells in the treated spheroids included the formation of porous cell membranes, crater-like holes (SEM), blebbing, and dissolution of cytoplasmic organelles (TEM). With continued culture, the injured spheroids were found to disaggregate after intensive131I-TNT-1 therapy (e.g. 50 µCi/ml or 100 µCi/ml with two or three 24-h treatments). These findings suggest that tumor spheroids can be used as an in vitro model to evaluate monoclonal antibody therapy using TNT-1 and other candidate mAbs directed against intracellular antigens exposed in degenerating cells of tumors.

Ten diffuse histiocytic lymphoma (DHL) cell lines were extensively characterized with monoclonal antibodies and histochemical techniques. The original biopsy specimens, representing nine of ten cases from which the cell lines were derived, were reviewed utilizing the International Working Formulation. Eight of ten cell lines reacted with antiimmunoglobulin reagents and/or a subset of B-lymphocyte surface markers, supporting a B-cell derivation. Only U-937, a monocytoid DHL cell line reactive with OKT4 and 6, displayed any T-cell markers. Cytochemical analysis alone proved to be of little value in the subclassification of the DHLs. The pathologic review revealed that, despite disparate immunologic phenotypes, five of the diffuse large cell lymphomas were subclassified as large, noncleaved lymphomas. Our analysis confirms the phenotypic diversity of this subgroup of malignant lymphomas and underscores the value of monoclonal reagents for the immunologic evaluation of the hematologic malignancies. These well characterized cell lines constitute a valuable resource for the laboratory investigation of the lymphomas.

We have examined the immunoglobulin gene configurations in cell lines from eight patients with diffuse histiocytic lymphoma in order to establish the cellular lineage and stage of differentiation of these lymphomas. The presence of heavy and light chain gene rearrangements as well as heavy chain class switching in seven cells placed these tumors within the B cell lineage. In contrast, one cell (SU-DHL-1), which lacks B cell-restricted surface antigens, retained germline heavy and light chain loci, indicating that it may represent a true histiocyte or uncommitted cell. Truncated RNAs for both the heavy and light chain immu-noglobulins were responsible for the lack of surface immunoglobulin in the SU-DHL-2 cell line. Another cell line (SU-DHL-6), which possesses a t(14;18)(q32;q21) translocation, demonstrated an unexpected recombination within its heavy chain gene locus that may be the interchromo-somal breakpoint.

A patient with Richter's syndrome, a malignant lymphomatous transformation of chronic lymphocytic leukemia, had become moribund with rapidly enlarging masses, granulocytopenia and thrombocytopenia despite the use of conventional chemotherapy and radiotherapy. Greater than ten percent of a test dose of I-131 Lym-1, a murine monoclonal antibody produced against Burkitt's African B cell lymphoma, was accumulated by her tumor. The patient was subsequently treated with a series of injections of I-131 Lym-1 with dramatic clinical response, reduction of tumor volume by x-ray computerized tomography and progression of circulating cellular elements toward normality. Her course over the next ten months was not like that to be expected for Richter's syndrome, which has an average survival of four months. This mode of treatment appears promising.

Estrogen receptor (ER) determinations were performed on cytosol preparations of Ficoll-Hypaque density separated mononuclear cells from 11 patients with chronic lymphocytic leukemia (CLL). The presence of ER was noted in 8 of 11 specimens (73%). ER ranged from 431 fmole/mg to 4.3 fmole/mg cytosol protein. Two types of receptor subunits were observed at the 8S and 4S region of the sucrose gradient. In addition, 1 of 3 Epstein-Barr virus (EBV) transformed B-lymphoblastoid cell lines from healthy donors had a measurable amount of ER. Patient R.L., who was refractory to standard chemotherapy and radiation and was ER positive, experienced a minor response to Tamoxifen therapy, with subsequent loss of ER. The demonstration of ER in CLL suggests that this malignancy may have a hormone-dependent subpopulation of cells.

Human B cell lymphoma (Raji) growing in athymic, nude mice has been successfully treated with a single pulse dose of 131I-labeled monoclonal antibody (Lym-1) specific for this tumor. Sequential invivomeasurements of phosphate metabolites in the tumors by 31P surface coil nuclear magnetic resonance showed a significant initial decrease of phosphocreatine following radioimmunotherapy. Diminution of relative ATP to Pi peak area ratio suggesting tissue damage occurred within 3–4 days. The contribution from metabolites resonating at ca 3.8 ppm (putative sugar phosphate region) increased. There was no significant change in pH either as a function of tumor volume or treatment. The sequence of alterations of nuclear magnetic resonance spectra from tumors of treated mice were strikingly different from sequential nuclear magnetic resonance spectra obtained from tumors of control mice. These observations lead us to conclude that 31P surface coil nuclear magnetic resonance is a promising non-invasive method for assessing and predicting the efficacy of radioimmunotherapy. Further spatial discrimination of the region of tissue observed by the surface coil nuclear magnetic resonance experiment is under exploration in an effort to increase the utility of these methods.

The genes involved in the t(12;22)(q13;q12) translocation found recurrently in malignant melanoma of soft parts have been characterized and shown to form, in four cases studied, hybrid transcripts. The deduced chimaeric protein encoded by the der(22) chromosome consists of the N–terminal domain of EWS linked to the bZIP domain of ATF–1, a transcription factor which may normally be regulated by cAMP. ATF–1 has not previously been implicated in oncogenesis. EWS was first identified as forming a hybrid transcript in Ewing's sarcoma, which links its N–terminal domain to the DNA binding domain of the FLI–1 gene. Thus the oncogenic conversion of EWS follows a common scheme of activation, exchanging its putative RNA binding domain with different DNA binding domains that appear to be tumour–specific.

A monoclonal antibody, designated BM-1, which is reactive in B5 formalin-fixed, paraffin-embedded tissues, has been generated against a cytoplasmic and nuclear antigen expressed in human myeloid precursor cells and derived leukemias. Using the avidin-biotin-complex immunoperoxidase procedure, BM-1 was found to stain selectively myeloid precursor cells in normal bone marrow and mature granulocytes in the blood. In a screen of 26 normal adult and fetal human organs fixed in B5 formalin, BM-1 was negative in all nonhematopoietic tissues with the exception of tissue granulocytes and scattered cells in the peripheral cortex of the thymus. Likewise a screen of 30 solid tumor cell lines including a spectrum of carcinomas, sarcomas, and neural-derived tumors was negative. BM-1 was also negative with 21 T and B cell lymphomas and 11 Hodgkin's disease tumors. A preliminary study of tumors of the hematopoietic system revealed that BM-1 was reactive with M2 and M3 acute myelogenous leukemias (AML), chronic myelogenous leukemias (CML) and myelomonocytic leukemias, and granulocytic sarcomas. M1, M4, M5, and M6 AML clot preparations were negative in this study, indicating that BM-1 may have a role in the histopathologic diagnosis of myelogenous leukemia. Myeloid leukemic cell lines HL-60, ML-2, KG1, and TPH-1-0 showed BM-1 nuclear and/or cytoplasmic reactivity in a subpopulation of cells, but erythroid and lymphoid leukemias and all lymphoma cell lines were negative. Immunoperoxidase studies of a panel of fetal tissues showed BM-1 positive cells in the peripheral cortex of the thymus and portal myelopoietic regions of the liver at 18 weeks gestation. Finally, DNA-cellulose and solid phase radioimmunoassay (RIA) techniques developed in our laboratory demonstrate that the BM-1 antigenic domain is reactive only after binding to eukaryotic but not prokaryotic single- or double-stranded DNA. Immunoblot techniques using a DNA-cellulose purified protein sample revealed that BM-1 recognizes a 183 kD protein. These studies indicate that BM-1 is recognizing a myeloid-specific antigen that, because of its DNA binding characteristics, may have an important role in the differentiation of myeloid cells at the molecular level.

Lym-2 is a murine monoclonal antibody (MoAb) directed towards a human class II molecule variant reactive with both normal and neoplastic human B lymphocytes. Previous studies have shown that signals transmitted by class II molecules that stimulate normal lymphocytes can be inhibitory for B-cell lymphoma growth by signaling activation-induced cell death. Therefore, we sought to evaluate the effects of nonconjugated murine Lym-2 and a human-mouse chimeric Lym-2 (chCLL-1; with murine variable regions and human constant regions) MoAb on the growth of various human lymphomas by using both in vitro and in vivo assays. Cell lines derived from Burkitt's lymphomas, diffuse large cell B-cell lymphomas, anaplastic large-cell lymphomas, and Epstein-Barr virus–induced B-cell lymphomas were incubated with Lym-2 or chCLL-1 in vitro, and effects on proliferation were determined by [3H]-thymidine incorporation. The effects of Lym-2 in vitro were also compared with those of Lym-1, which is a similar MoAb that has been evaluated clinically. After immobilization, which enhances crosslinking of the MoAbs, both Lym-2 and chCLL-1 were capable of directly inhibiting the growth of various lymphoma lines in vitro. These human lymphomas were then transferred into mice with severe combined immunodeficiency to evaluate the efficacy of these MoAbs in vivo. Treatment with either murine Lym-2 or the chimeric chCLL-1 were significantly effective in improving the survival of tumor-bearing mice. These results indicate that stimulation by nonconjugated chCLL-1 may offer a biological approach to the treatment of various human lymphomas.

Although monoclonal antibody (MoAb) therapy of the human malignant lymphomas has shown success in clinical trials, its full potential for the treatment of hematologic malignancies has yet to be realized. To expand the clinical potential of a promising human-mouse chimeric antihuman B-cell MoAb (chCLL-1) constructed using the variable domains cloned from the murine Lym-2 (muLym-2) hybridoma, fusion proteins containing granulocyte-macrophage colony-stimulating factor (GM-CSF) (chCLL-1/GM–CSF) or interleukin (IL)-2 (chCLL-1/IL–2) were generated and evaluated for in vitro cytotoxicity and in vivo tumor targeting. The glutamine synthetase gene amplification system was employed for high level expression of the recombinant fusion proteins. Antigenic specificity was confirmed by a competition radioimmunoassay against ARH-77 human myeloma cells. The activity of chCLL-1/GM–CSF was established by a colony formation assay, and the bioactivity of chCLL-1/IL–2 was confirmed by supporting the growth of an IL-2–dependent T-cell line. Antibody-dependent cellular cytotoxicity against ARH-77 target cells demonstrated that both fusion proteins mediate enhanced tumor cell lysis by human mononuclear cells. Finally, biodistribution and imaging studies in nude mice bearing ARH-77 xenografts indicated that the fusion proteins specifically target the tumors. These in vitro and in vivo data suggest that chCLL-1/GM–CSF and chCLL-1/IL–2 have potential as immunotherapeutic reagents for the treatment of B-cell malignancies.

Specific chromosomal translocations found in distinct neoplasms suggest that genes that flank such breakpoints play a critical role in transformation. We have characterized the t(14;18)(g32;q21) chromosomal translocation present in over 60% of human follicular lymphomas. We exploited an unexpected rearrangement of an Ig heavy-chain gene to clone the chromosomal breakpoint. An element isolated from 18q21 mediated translocations in all four t(14;18) bearing cell lines and in six of 11 follicular lymphomas, but did not normally rearrange in other B or non-B cells. The breakpoints clustered within a small 4.3 kb region on chromosome 18. The breakpoints on chromosome 14 were focused within or immediately 5′ to JH. These breakpoints retained the Ig enhancer region close to a new transcriptional unit identified on chromosome segment 18g21. Since none of the cellular oncogenes are known to map to 18g21, cloning this element provides an opportunity to characterize a potentially new transforming gene.

A murine anti-human B-cell monoclonal antibody, Lym-1, has shown considerable promise for the treatment of human malignant lymphomas and has been utilized as a new radioimmunotherapy for refractory lymphoma. In order to enhance its clinical potential, a genetically engineered chimeric Lym-1 (chLym-1) with murine variable reyions and human γl and κ constant reyions was constructed and expressed. The goal of this study was to yenerate a Lym-1 reayent with decreased immunoyenicity and improved effector functions. Murine Lym-1 variable region cDNAs were isolated from the murine Lym-1 hybridoma cell line, fused to γl and κ constant region cDNAs, and expressed in an insect cell expression system with the baculovirus transfer vector pAcUW31. The chLym-1 antibody expressed in this system was correctly processed and assembled into the expected immunoglobulin monomer. Chimeric Lym-1 bound to both target antigen-bearing Raji cells and a Lym-1 anti-idiotype antibody and had a similar binding affinity as murine Lym-1. The chimeric and murine versions of Lym-1 were assayedfor their ability to mediate antibody-dependent cellular cytotoxicity (ADCC) and to induce complement-mediated cytotoxicity (CMC) against Raji targets. Chimeric Lym-1 mediated a two-fold hiyher level of ADCC than murine Lym-1 and slightly lower levels of CMC than murine Lym-1. In addition, in Raji lymphoma-bearing nude mice, chLym-1 localized to the tumor with approximately equal uptake at 24 and 72 hours. Chimeric Lym-1, however, cleared from the blood of non tumor-bearing mice approximately 5 times faster than murine Lym-1 (20h vs. 5 days), as expected for a xenogeneic protein. The improved in vitro and in vivo activities of this genetically enyineered monoclonal antibody render it a new potential immunotherapeutic reagent for the treatment of human malignant lymphomas.

Two monoclonal antibodies (LN-4, LN-5) reactive to human macrophages in B5 formalin-fixed, paraffin-embedded tissue sections have been produced by using deparaffinized cell extracts of peripheral blood mononuclear cells. Both monoclonal antibodies were initially identified on paraffin-embedded sections of hyperplastic lymph nodes by using the immunoperoxidase staining procedure. Specificity screens on normal human tissues show that LN-4 and LN-5 stain the cytoplasm of macrophages and histiocytes in hematopoietic organs including Kuppfer's cells of the liver and Langerhans’ cells of the skin. LN-4 also showed strong positivity with acini of the stomach, whereas LN-5 was positive with mantle zone B lymphocytes of the lymph node and spleen, spermatogonia, and chief cells of the stomach. Both antibodies were strongly reactive with cases of true histiocytic lymphoma but, except for infiltrating macrophages, were entirely negative in Hodgkin's disease and non-Hodgkin's lymphomas. In all cases of nodular sclerosis Hodgkin's disease, LN-4 was positive in macrophagelike cells present in the collagen bands surrounding the Hodg-kin's lesions. Both monoclonal antibodies were also positive in macrophages and histiocytes present in a variety of benign lymphoid lesions including persistent generalized lymphadenopathy, Gaucher's disease, sinus histiocytosis, and dermatopathic lymphadenopathy. Because of their specificity for human macrophages, and their ability to stain B5-fixed, paraffin-embedded tissues, LN-4 and LN-5 are important new reagents for the diagnosis and classification of malignant and benign histiocytic lesions.©1988 by Grune & Stratton, Inc. 0006-4971188/7104-0023$3.00/0

ABSTRACTImmune checkpoint therapy has resulted in minimal clinical response in many pediatric cancers. We sought to understand the influence of immune checkpoint inhibition using anti-PD-1 and anti-CTLA-4 antibodies individually, in combination, and after chemotherapy on immune responses in minimal and established murine neuroblastoma models. We also sought to understand the role of the tumor microenvironment (TME) and PD-L1 expression and their alteration post-chemotherapy in our models and human tissues. PD-L1 expression was enriched in human tumor-associated macrophages and up-regulated after chemotherapy. In a murine minimal disease model, single and dual immune checkpoint blockade promoted tumor rejection, improved survival, and established immune memory with long-term anti-tumor immunity against re-challenge. In an established tumor model, only dual immune checkpoint blockade showed efficacy. Interestingly, dual immune checkpoint therapy distinctly influenced adaptive and innate immune responses, with significant increase in CD8+CD28+PD-1+T cells and inflammatory macrophages (CD11bhiCD11c−F4/80+Ly6Chi) in tumor-draining lymph nodes. Adding chemotherapy before immunotherapy provided significant survival benefit for mice with established tumors receiving anti-PD-1 or dual immune checkpoint blockade. Our findings demonstrate anti-PD-1 and anti-CTLA-4 therapy induces a novel subset of effector T cells, and support administration of induction chemotherapy immediately prior to immune checkpoint blockade in children with high-risk neuroblastoma.

A painful and swollen prosthetic joint, accompanied by fever, is considered to be an intraarticular infection until proven otherwise. Acute gout is one of the rare causes of arthritis in a prosthetic joint, and it may be misdiagnosed as an infection, especially when a high leukocyte count is present in the joint fluid.

Breast Implant Associated Large Cell Lymphoma (BIA-ALCL) is a recently recognized lymphoma found surrounding breast implants of more than 380 women worldwide. The etiology of BIA-ALCL is unknown although a bacterial biofilm overlying BIA-ALCL associated implants has been demonstrated. Here we provide evidence that BIA-ALCL may be mediated by chronic allergic inflammation in a group of BIA-ALCL patients. We studied 3 BIA-ALCL lines (TLBR-1/2/3), seroma fluids and/or resected capsular tissues of 14 patients with BIA-ALCL. Resected capsules revealed chronic inflammation including fibrosis, plasma cells, lymphocytes, primary and secondary lymphoid follicles, mast cells and eosinophils. IL-13, the signature cytokine of allergic inflammation, was secreted by BIA-ALCL lines and localized to small lymphocytes and anaplastic cells in most clinical samples. Th2 transcription factor GATA3 co-localized to anaplastic cells producing IL-13. IL-13 is known to induce Ig class switch of B cells to produce IgE. Accordingly, IgE was detected bound to follicular dendritic antigen presenting cells in lymphoid follicles in 3 cases and mast cells in 5 cases. As a likely source of IgE, plasma cells staining for IgE were found in capsular tissues and regional lymph nodes. Activated mast cells produce prostaglandin D2(PGD2). The receptor for PGD2, CRTH2, was expressed by each of 3 BIA-ALCL lines and anaplastic cells in 5 of 6 clinical samples analyzed. Ligands that activate CRTH2 stimulate chemotaxis (i.e. directed migration) of leukocytes active in mediating allergic responses, viz., eosinophils, basophils, and Th2 cells. Not unexpectedly, eosinophils were found surrounding anaplastic cells in 4 of 5 cases with IgE observed on mast cells. In contrast, only few scattered tissue and intravascular eosinophils were present in 1 of 15 benign capsules. Together, these findings suggest that some BIA-ALCL are associated with a chronic allergic immune response to as yet undefined antigen(s).

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

Tumor spheroids of HT-29 human colon adenocarcinoma and A375 melanoma were established to investigate the uptake and clearance kinetics of TNT-1, a monoclonal antibody that targets ne-crotic cells of tumors. Our data reveal that there was rapid uptake of TNT-1 and its F(ab‘)2 fragment in both spheroid models, whereas an antibody of irrelevant specificity, Lym-1, and its F(ab’)2 fragment bound poorly to the spheroids. Unlike previously reported monoclonal antibodies to tumor cell-surface antigens, TNT-1 showed 1) a linear uptake that increased over time without saturation in tumor spheroids and 2) an unexpected uptake by a sub-population of cells in the viable outer rim of the spheroids. These preclinical studies provide important information concerning the therapeutic potential of TNT monoclonal antibodies for the treatment of cancer and micro-metastases. [J Natl Cancer Inst 83:200–204, 1991]