Tumor-targeted CD28 bispecific antibodies enhance the antitumor efficacy of PD-1 immunotherapy.

Monoclonal antibodies that block the programmed cell death 1 (PD-1) checkpoint have revolutionized cancer immunotherapy. However, many major tumor types remain unresponsive to anti-PD-1 therapy, and even among responsive tumor types, most of the patients do not develop durable antitumor immunity. It has been shown that bispecific antibodies activate T cells by cross-linking the TCR/CD3 complex with a tumor-specific antigen (TSA). The class of TSAxCD3 bispecific antibodies have generated exciting results in early clinical trials. We have recently described another class of "costimulatory bispecifics" that cross-link a TSA to CD28 (TSAxCD28) and cooperate with TSAxCD3 bispecifics. Here, we demonstrate that these TSAxCD28 bispecifics (one specific for prostate cancer and the other for epithelial tumors) can also synergize with the broader anti-PD-1 approach and endow responsiveness-as well as long-term immune memory-against tumors that otherwise do not respond to anti-PD-1 alone. Unlike CD28 superagonists, which broadly activate T cells and induce cytokine storm, TSAxCD28 bispecifics display little or no toxicity when used alone or in combination with a PD-1 blocker in genetically humanized immunocompetent mouse models or in primates and thus may provide a well-tolerated and "off the shelf" combination approach with PD-1 immunotherapy that can markedly enhance antitumor efficacy.

Enhanced IL-36R signaling promotes barrier impairment and inflammation in skin and intestine.

Deficiency in interleukin-36R (IL-36R) antagonist caused by loss-of-function mutations in IL-36RN leads to DITRA (deficiency of IL-36 receptor antagonist), a rare inflammatory human disease that belongs to a subgroup of generalized pustular psoriasis (GPP). We report a functional genetic mouse model of DITRA with enhanced IL-36R signaling analogous to that observed in patients with DITRA, which provides new insight into our understanding of the IL-36 family of molecules in regulating barrier integrity across multiple tissues. Humanized DITRA-like mice displayed increased skin inflammation in a preclinical model of psoriasis, and in vivo blockade of IL-36R pathway using anti-human IL-36R antibody ameliorated imiquimod-induced skin pathology as both prophylactic and therapeutic treatments. Deeper characterization of the humanized DITRA-like mice revealed that deregulated IL-36R signaling promoted tissue pathology during intestinal injury and led to impairment in mucosal restoration in the repair phase of chronic dextran sulfate sodium (DSS)-induced colitis. Blockade of IL-36R pathway significantly ameliorated DSS-induced intestinal inflammation and rescued the inability of DITRA-like mice to recover from mucosal damage in vivo. Our results indicate a central role for IL-36 in regulating proinflammatory responses in the skin and epithelial barrier function in the intestine, suggesting a new therapeutic potential for targeting the IL-36R axis in psoriasis and at the later stages of intestinal pathology in inflammatory bowel disease.

A Mucin 16 bispecific T cell-engaging antibody for the treatment of ovarian cancer.

Advanced ovarian cancer is frequently treated with combination chemotherapy, but high recurrence rates show the need for therapies that can produce durable responses and extend overall survival. Bispecific antibodies that interact with tumor antigens on cancer cells and activating receptors on immune cells offer an innovative immunotherapy approach. Here, we describe a human bispecific antibody (REGN4018) that binds both Mucin 16 (MUC16), a glycoprotein that is highly expressed on ovarian cancer cells, and CD3, thus bridging MUC16-expressing cells with CD3+ T cells. REGN4018 induced T cell activation and killing of MUC16-expressing tumor cells in vitro. Binding and cytotoxicity of REGN4018 in vitro were minimally affected by high concentrations of CA-125, the shed form of MUC16, which is present in patients. In preclinical studies with human ovarian cancer cells and human T cells in immunodeficient mice, REGN4018 potently inhibited growth of intraperitoneal ovarian tumors. Moreover, in a genetically engineered immunocompetent mouse expressing human CD3 and human MUC16 [humanized target (HuT) mice], REGN4018 inhibited growth of murine tumors expressing human MUC16, and combination with an anti-PD-1 antibody enhanced this efficacy. Immuno-PET imaging demonstrated localization of REGN4018 in MUC16-expressing tumors and in T cell-rich organs such as the spleen and lymph nodes. Toxicology studies in cynomolgus monkeys showed minimal and transient increases in serum cytokines and C-reactive protein after REGN4018 administration, with no overt toxicity. Collectively, these data demonstrate potent antitumor activity and good tolerability of REGN4018, supporting clinical evaluation of REGN4018 in patients with MUC16-expressing advanced ovarian cancer.

Characterization of the Anti-PD-1 Antibody REGN2810 and Its Antitumor Activity in Human PD-1 Knock-In Mice.

The Programmed Death-1 (PD-1) receptor delivers inhibitory checkpoint signals to activated T cells upon binding to its ligands PD-L1 and PD-L2 expressed on antigen-presenting cells and cancer cells, resulting in suppression of T-cell effector function and tumor immune evasion. Clinical antibodies blocking the interaction between PD-1 and PD-L1 restore the cytotoxic function of tumor antigen-specific T cells, yielding durable objective responses in multiple cancers. This report describes the preclinical characterization of REGN2810, a fully human hinge-stabilized IgG4(S228P) high-affinity anti-PD-1 antibody that potently blocks PD-1 interactions with PD-L1 and PD-L2. REGN2810 was characterized in a series of binding, blocking, and functional cell-based assays, and preclinical in vivo studies in mice and monkeys. In cell-based assays, REGN2810 reverses PD-1-dependent attenuation of T-cell receptor signaling in engineered T cells and enhances responses of human primary T cells. To test the in vivo activity of REGN2810, which does not cross-react with murine PD-1, knock-in mice were generated to express a hybrid protein containing the extracellular domain of human PD-1, and transmembrane and intracellular domains of mouse PD-1. In these mice, REGN2810 binds the humanized PD-1 receptor and inhibits growth of MC38 murine tumors. As REGN2810 binds to cynomolgus monkey PD-1 with high affinity, pharmacokinetic and toxicologic assessment of REGN2810 was performed in cynomolgus monkeys. High doses of REGN2810 were well tolerated, without adverse immune-related effects. These preclinical studies validate REGN2810 as a potent and promising candidate for cancer immunotherapy. Mol Cancer Ther; 16(5); 861-70. ©2017 AACR.

Improved multiple displacement amplification with phi29 DNA polymerase for genotyping of single human cells.

The ability to genotype multiple loci of single cells would be of significant benefit to investigations of cellular processes such as oncogenesis, meiosis, fertilization, and embryogenesis. We report a simple two-step, single-tube protocol for whole-genome amplification (WGA) from single human cells using components of the GenomiPhi V2 DNA Amplification kit. For the first time, we demonstrate reliable generation of 4-7 microg amplified DNA from a single human cell within 4 h with a minimum amount of artifactual DNA synthesis. DNA amplified from single cells was genotyped for 13 heterozygous short tandem repeats (STRs) and 7 heterozygous single nucleotide polymorphisms (SNPs), and the genotyping results were compared with purified genomic DNA. Accuracy of genotyping (percent of single-cell amplifications genotyped accurately for any particular STR or SNP) varied from 37% to 100% (with an average of 80%) for STRs and from 89% to 100% (averaging 94%) for SNPs. We suggest that the method described in this report is suitable for WGA from single cells, the product of which can be subsequently used for many applications, such as preimplantation genetic analysis (PGD).

Anaerobranca zavarzinii sp. nov., an anaerobic, alkalithermophilic bacterium isolated from Kamchatka thermal fields.

A novel obligately anaerobic, alkalithermophilic, chemo-organotrophic bacterium was isolated from a small and very shallow geothermally heated pool at Pushino (Kamchatka, Far East Russia). The bacterium, designated strain JW/VK-KS5Y(T), was a Gram staining negative, Gram type positive rod. The cells were sometimes branched, with a tendency to grow in long chains, and were non-sporulating and non-motile. The shortest observed doubling time was 28 min when the novel strain was grown at 54-60 degrees C in 120 mM sodium carbonate-containing medium at pH(25 degrees C) 8.5-9.0. The novel bacterium grew on yeast extract and soytone as sole carbon and energy sources but could also use fumarate, thiosulfate and sulfur as electron acceptors. The DNA G+C content was 32.5 mol%. Based on phylogenetic, DNA-DNA hybridization and phenotypic data, it was concluded that isolate JW/VK-KS5Y(T) (=VKM B-2436(T)=DSM 18970(T)) represents the type strain of a novel species, Anaerobranca zavarzinii sp. nov.

Anaerobic, alkaliphilic, saccharolytic bacterium Alkalibacter saccharofermentans gen. nov., sp. nov. from a soda lake in the Transbaikal region of Russia.

Three strains of new obligately anaerobic alkaliphilic bacteria have been isolated as a saccharolytic component from the cellulolytic community of alkaline Lake Nizhnee Beloe (Transbaikal region, Russia), a lake with low salt concentration. DNA analysis of these strains showed an interspecies level of DNA similarity of 96-100%. Strain Z-79820 was selected for further investigations. Cells were Gram-positive, asporogenous, nonmotile short rods with pointed ends. The strain was a true alkaliphile: growth occurred from pH 7.2 to 10.2 with the optimum at pH 9.0. Strain Z-79820 was halotolerant and could grow in medium with up to 10% (w/v) NaCl, with the optimum between 0 and 4% NaCl. The new isolate obligately depended on Na+ ions in the form of carbonates or chlorides. Total Na+ content needed for optimal growth was 0.46 M Na+, with a wide range from 0.023-0.9 M Na+ at which growth also occurred. The isolate was a mesophile and grew at temperatures from 6 to 50 degrees C (slow growth at 6 and 15 degrees C) with an optimum at 35 degrees C. The organotrophic organism fermented ribose, xylose, glucose, mannose, fructose, sucrose, mannitol, and peptone. The products of glucose fermentation were acetate, ethanol, formate, H2, and CO2. Yeast extract was required for some anabolic needs. The DNA G+C content of the type strain Z-79820 was 42.1 mol%. The new bacterium fell into the 16S rRNA gene cluster XV of the Gram-positive bacteria with low G+C content, where it formed an individual branch. Based on its growth characteristics and genotype traits, we propose the new genus and species named Alkalibacter saccharofermentans with the type strain Z-79820 (=DSM14828), Uniqem-218 (Institute Microbiology, RAS; http://inmi.da.ru).

Anoxynatronum sibiricum gen.nov., sp.nov. alkaliphilic saccharolytic anaerobe from cellulolytic community of Nizhnee Beloe (Transbaikal region).

New alkaliphilic anaerobic fermentative bacteria, strains Z-7981 and Z-7981', with Gram-positive cell walls, were isolated from the cellulolytic community from the soda lake Nizhnee Beloye, south-east of Baikal. Cells were motile rods, which differed in dimensions but, according to 98% DNA/DNA homology, belonged to the same species. Strain Z-7981 was chosen as the type and studied in detail. It did not produce spores and its cells were non-thermoresistant. It was a true alkaliphile with a growth range from pH 7.1 to pH 10.1 and optimal pH for growth at pH 9.1. It was obligately dependent on Na(+) and carbonate ions but not on Cl(-). Growth occurred in media with total sodium content from 0.076 M to 1.27 M Na(+ )with a broad optimum from 0.25 to 0.86 M Na(+). Growth showed an optimum at 35 degrees C, with absence of growth above 46 degrees C. The organism was aerotolerant and was capable of fermentation in non-reducing medium at less than 4.75% O(2) in the gas phase. Strain Z-7981 fermented mono- and disaccharides, sugar alcohols, but only glutamate and cysteine among the amino acids, and the proteinaceous substrates, chitin and dried Spirulina biomass. Fermentation products were acetate and ethanol. Fe(3+) was reduced in a process that yielded no energy. Phylogenetically the new organism belonged to cluster XI of the Gram-positive bacteria with low G+C content and its closest neighboring taxon was Tindallia magadiensis. However, according to its phenotypic and genotypic characters it did not belong to any known genus from this group. We suggest a new genus and species with the name Anoxynatronum sibiricum and strain Z-7981 as its type (=DSM15060).