Preclinical development of novel PD-L1 tracers and first-in-human study of [68Ga]Ga-NOTA-RW102 in patients with lung cancers.

BACKGROUND: The programmed cell death protein-1 (PD-1)/programmed death receptor ligand 1 (PD-L1) axis critically facilitates cancer cells' immune evasion. Antibody therapeutics targeting the PD-1/PD-L1 axis have shown remarkable efficacy in various tumors. Immuno-positron emission tomography (ImmunoPET) imaging of PD-L1 expression may help reshape solid tumors' immunotherapy landscape. METHODS: By immunizing an alpaca with recombinant human PD-L1, three clones of the variable domain of the heavy chain of heavy-chain only antibody (VHH) were screened, and RW102 with high binding affinity was selected for further studies. ABDRW102, a VHH derivative, was further engineered by fusing RW102 with the albumin binder ABD035. Based on the two targeting vectors, four PD-L1-specific tracers ([68Ga]Ga-NOTA-RW102, [68Ga]Ga-NOTA-ABDRW102, [64Cu]Cu-NOTA-ABDRW102, and [89Zr]Zr-DFO-ABDRW102) with different circulation times were developed. The diagnostic efficacies were thoroughly evaluated in preclinical solid tumor models, followed by a first-in-human translational investigation of [68Ga]Ga-NOTA-RW102 in patients with non-small cell lung cancer (NSCLC). RESULTS: While RW102 has a high binding affinity to PD-L1 with an excellent KD value of 15.29 pM, ABDRW102 simultaneously binds to human PD-L1 and human serum albumin with an excellent KD value of 3.71 pM and 3.38 pM, respectively. Radiotracers derived from RW102 and ABDRW102 have different in vivo circulation times. In preclinical studies, [68Ga]Ga-NOTA-RW102 immunoPET imaging allowed same-day annotation of differential PD-L1 expression with specificity, while [64Cu]Cu-NOTA-ABDRW102 and [89Zr]Zr-DFO-ABDRW102 enabled longitudinal visualization of PD-L1. More importantly, a pilot clinical trial shows the safety and diagnostic value of [68Ga]Ga-NOTA-RW102 immunoPET imaging in patients with NSCLCs and its potential to predict immune-related adverse effects following PD-L1-targeted immunotherapies. CONCLUSIONS: We developed and validated a series of PD-L1-targeted tracers. Initial preclinical and clinical evidence indicates that immunoPET imaging with [68Ga]Ga-NOTA-RW102 holds promise in visualizing differential PD-L1 expression, selecting patients for PD-L1-targeted immunotherapies, and monitoring immune-related adverse effects in patients receiving PD-L1-targeted treatments. TRIAL REGISTRATION NUMBER: NCT06165874.

Noninvasive PET imaging of tumor PD-L1 expression with 64Cu-labeled Durvalumab.

Breast cancer (BrCa) ranks as the most prevalent malignant neoplasm affecting women worldwide. The expression of programmed death-ligand 1 (PD-L1) in BrCa has recently emerged as a biomarker for immunotherapy response, but traditional immunohistochemistry (IHC)-based methods are hindered by spatial and temporal heterogeneity. Noninvasive and quantitative PD-L1 imaging using appropriate radiotracers can serve to determine PD-L1 expression in tumors. This study aims to demonstrate the viability of PET imaging with 64Cu-labeled Durvalumab (abbreviated as Durva) to assess PD-L1 expression using a murine xenograft model of breast cancer. Durvalumab, a human IgG1 monoclonal antibody against PD-L1, was assessed for specificity in vitro in two cancer cell lines (MDA-MB-231 triple-negative breast cancer cell line and AsPC-1 pancreatic cancer cell line) with positive and negative PD-L1 expression by flow cytometry. Next, we performed the in vivo evaluation of 64Cu-NOTA-Durva in murine models of human breast cancer by PET imaging and ex vivo biodistribution. Additionally, mice bearing AsPC-1 tumors were employed as a negative control. Tumor uptake was quantified based on a 3D region-of-interest (ROI) analysis of the PET images and ex vivo biodistribution measurements, and the results were compared against conventional IHC testing. The radiotracer uptake was evident in MDA-MB-231 tumors and showed minimal nonspecific binding, corroborating IHC-derived results. The results of the biodistribution showed that the MDA-MB-231 tumor uptake of 64Cu-NOTA-Durva was much higher than 64Cu-NOTA-IgG (a nonspecific radiolabeled IgG). In Conclusion, 64Cu-labeled Durvalumab PET/CT imaging offers a promising, noninvasive approach to evaluate tumor PD-L1 expression.

Metal-organic frameworks-based biosensor for microRNA detection in prostate cancer cell lines.

In this research, a novel dye-labeled probe (FAM-Probe) based on a nano metal-organic framework (NMOF) functionalized with folate (NMOF-FA) was prepared and applied as a fluorescent sensing platform for the recognition of intracellular microRNA (miRNA-21) in DU145, PC3, and LNCaP cancer cells. The NMOF-FA can be easily assembled with a dye-labeled miR-21 probe (FAM-Probe21), causing an efficient fluorescence quenching of fluorescence of FAM fluorophore. The probe can be specifically catch up by cancerous cells through targeting their folate receptor by folic acid on the FAM-Probe21-NMOF-FA complex. Upon the interaction of the FAM-Probe21-NMOF-FA with complementary miRNA (miR-21), the fluorescence intensity can be recovered, providing a specific system to detect miRNAs in prostate cancer cells. We used the proposed probe for cell-specific intracellular miRNA-21 sensing, following the alteration expression level of miRNA-21 inside living cells. Thus, the FAM-Probe21-NMOF-FA complex can be used as a new miRNA sensing method in biomedicine studies.

Functional mimetic peptide discovery isolated by phage display interacts selectively to fibronectin domain and inhibits gelatinase.

Matrix metalloproteinases (MMPs) play critical roles in a multiple number of autoimmunity diseases progression and metastasis of solid tumor. Gelatinases including MMP-2 and MMP-9 are extremely overexpressed in multiple pathological processes. MMP-9 and MMP-2 breakdown the extracellular matrix component gelatin very efficaciously. Therefore, designing and expansion of MMPs inhibitors can be an engrossing plan for therapeutic intermediacy. Anyway, a wide range of MMPs inhibitors face failure in several clinical trials. Due to sequence and structural conservation across the various MMPs, achieving specific and selective inhibitors is very demanding. In the current study, a phage-displayed peptide library was screened using active human recombinant MMP-9 protein and evaluated by enzyme-linked immunosorbent assay. Here, we isolate novel peptide sequence from phage display peptide libraries that can be a specific gelatinase inhibitor. Interestingly, in silico molecular docking showed strong interactions between the peptide three-dimensional models and some important residues of the MMP-9 and MMP-2 proteins at the fibronectin domain. A consensus peptide sequence was then synthesized (named as RSH-12) to evaluate its inhibitory potency by in vitro assays. Zymography assay was employed to evaluate the effect of RSH-12 on gelatinolysis activity of MMP-2 and MMP-9 secretion from the HT1080 cells using different concentrations of RSH-12 and inhibiting MMP-9- and MMP-2-driven gelatin proteolysis, measured by fluorescein isothiocyanate-gelatin degradation assay and HT1080 cell invasion assay on Matrigel (gelatinous protein mixture). The negative control peptide (CP) with the irrelevant sequence and no MMP inhibition properties and the positive control compound (GM6001) as a potent inhibitor of MMPs were used to assess the selectivity and specificity of gelatinases inhibition by RSH-12. Therefore, RSH-12 decreased the gelatin degradation by specifically preventing gelatin binding to MMP-9 and MMP-2. Selective gelatinase inhibitors may prove the usefulness of the new peptide discovered in tumor targeting and anticancer and anti-inflammation therapies.

A caspase 8-based suicide switch induces apoptosis in nanobody-directed chimeric receptor expressing T cells.

In accordance with the two-step hypothesis of T cell activation and the observation that stimulation through the T cell receptor (TCR) alone may lead to anergy, we focused on the introduction of co-stimulatory signaling to this type of receptors to achieve optimal activation. Enhanced mRNA and cell surface receptor expression via the co-stimulatory gene fragment (OX40) was confirmed by RT-PCR and flow cytometry. Inclusion of the OX40 co-stimulatory signaling region in series with the TCR led to enhanced antigen-induced IL-2 production after stimulation by MUC1-expressing cancer cell lines as compared to the chimeric receptor without OX40. Moreover, with the aim of maintaining high efficiency, while providing a means of controlling any possible unwanted proliferation in vivo, a regulation system was used. This controls the dimerization of a membrane-bound caspase 8 protein. Toward that goal, pFKC8 and CAR constructs were co-transfected into Jurkat cells, and the level of apoptosis was measured. 24 h after addition of the dimerizer, a 91% decrease in transfected cells was observed.

Nanobody-based chimeric receptor gene integration in Jurkat cells mediated by φC31 integrase.

The crucial role of T lymphocytes in anti-tumor immunity has led to the development of novel strategies that can target and activate T cells against tumor cells. Recombinant DNA technology has been used to generate non-MHC-restricted chimeric antigen receptors (CARs). Here, we constructed a panel of recombinant CAR that harbors the anti-MUC1 nanobody and the signaling and co-signaling moieties (CD3ζ/CD28) with different spacer regions derived from human IgG3 with one or two repeats of the hinge sequence or the hinge region of FcγRII. The PhiC31 integrase system was employed to investigate if the recombination efficiency could be recruited for high and stable expression of T cell chimeric receptor genes. The effect of nuclear localization signal (NLS) and two different promoters (CMV and CAG) on efficacy of PhiC31 integrase in human T cell lines was evaluated. The presence of integrase in combination with NLS, mediated up to 7.6 and 8.5 fold increases in CAR expression in ZCHN-attB and ZCHHN-attB cassette integrated T cells, respectively. Our results showed that highly efficient and stable transduction of the Jurkat cell line by PhiC31 integrase is a feasible modality for generating anti-cancer chimeric T cells for use in cancer immunotherapy.

Combined MUC1-specific nanobody-tagged PEG-polyethylenimine polyplex targeting and transcriptional targeting of tBid transgene for directed killing of MUC1 over-expressing tumour cells.

We provide evidence for combining a single domain antibody (nanobody)-based targeting approach with transcriptional targeting as a safe way to deliver lethal transgenes to MUC1 over-expressing cancer cells. From a nanobody immune library, we have isolated an anti-DF3/Mucin1 (MUC1) nanobody with high specificity for the MUC1 antigen, which is an aberrantly glycosylated glycoprotein over-expressed in tumours of epithelial origin. The anti-MUC1 nanobody was covalently linked to the distal end of poly(ethylene glycol)(3500) (PEG(3500)) in PEG(3500)-25kDa polyethylenimine (PEI) conjugates and the resultant macromolecular entity successfully condensed plasmids coding a transcriptionally targeted truncated-Bid (tBid) killer gene under the control of the cancer-specific MUC1 promoter. The engineered polyplexes exhibited favourable physicochemical characteristics for transfection and dramatically elevated the level of Bid/tBid expression in both MUC1 over-expressing caspase 3-deficient (MCF7 cells) and caspase 3-positive (T47D and SKBR3) tumour cell lines and, concomitantly, induced considerable cell death. Neither transgene expression nor cell death occurred when the MUC1 promoter was replaced with the CNS-specific synapsin I promoter. Since PEGylated PEI was only responsible for DNA compaction and played no significant role in direct transfection and cell killing, our attempts overcome previously reported PEI-mediated apoptotic and necrotic cell death, which is advantageous for future in vivo transcriptional targeting as this will minimize (or eliminate) non-targeted cell damage.

Protection of BALB/C mice against Brucella abortus 544 challenge by vaccination with combination of recombinant human serum albumin-l7/l12 (Brucella abortus ribosomal protein) and lipopolysaccharide.

BACKGROUND: The immunogenic Brucella abortus ribosomal protein L7/L12 and Lipopolysaccharide (LPS) are promising candidate antigens for the development of subunit vaccines against brucellosis. OBJECTIVE: This study was aimed to evaluate the protection of combination of recombinant HSA-L7/L12 fusion protein with LPS in Balb/c mouse. MATERIALS AND METHODS: The recombinant HSA-L7/L12 fusion protein in Saccharomyces cerevisiae was expressed and purified by affinity chromatography column. LPS was extracted by n-butanol, purified by ultracentrifugation. BALB/c mouses were immunized in 9 groups with PBS, HSA, tHSA-L7/L12, L7/L12, LPS, LPS+ HSA, LPS+ tHSA-L7/L12, LPS+ L7/L12, B. abortus S19. ELISA, LTT tests and challenging two weeks after last injection were carried out. Bacterial count of spleen of immunized BALB/c mouse was done four weeks after challenging with virulent strain B. abortus 544. RESULTS: In ELISA test the specific antibodies of tHSA-L7/L12 exhibited a dominance of immunoglobulin IgG1 over IgG2a. LPS-HSA and tHSA-L7/L12 + LPS produced a significantly higher antibody titer than LPS alone and L7/L12+LPS (P < 0.05). The predominant IgG subtype for LPS and L7/L12+LPS were IgG3. However, tHSA-L7/L12+ LPS and LPS+ HAS elicited predominantly IgG1 and IgG3 subtypes. In addition, the tHSA-L7/L12 fusion protein and L7/L12 elicited a strong T-cell proliferative response upon restimulation in vitro with recombinant tHSA-L7/L12 and L7/L12, suggesting the induction of a cellular immunity response in vivo. However, there was no significant difference proliferative response in L7/L12 and tHSA-L7/L12 fusion protein (P > 0.05). The combination of tHSA-L7/L12 fusion protein with LPS and B. abortus S19 induce higher level of protection against challenge with the virulent strain B. abortus 544 in BALB/c mice than other groups (P = 0.005). CONCLUSIONS: The combination of tHSA-L7/L12 fusion protein with LPS had higher protective ability than LPS and fusion protein distinctly.

Hybrid promoters directed tBid gene expression to breast cancer cells by transcriptional targeting.

Developing cancer gene therapy constructs based on transcriptional targeting of genes to cancer cells is a new and promising modality for treatment of cancer. Introducing truncated Bid (tBid), a recently known member of the Bcl-2 family, eradicates cancer cells efficiently. For transcriptional targeting of tBid, two dual-specificity promoters, combining cancer specific core promoters and response modules, were designed. These two core promoter modules contained cancer specific promoters of MUC1 and Survivin genes accompanied by hypoxia-responsive elements and estrogen responsive elements (microenvironment condition of breast cancer cells) which were employed to achieve a higher and more specific level of tBid expression in breast cancer cells. Correlation of the level of tBid expression in normal and cancer cell lines with promoter activity was measured by RT-PCR after treatment with hypoxia and estrogen. The level of tBid expression under control of new hybrid promoters was compared with its expression under control of cytomegalovirus (CMV) promoter as a control. Our data revealed that the level of tBid expression in breast cancer cells were nearly 11 times more than normal cells because of the cancer specific promoters, although tBid expression under control of CMV promoter was almost the same in normal and cancer cell lines. Increased apoptosis was detected in the transfected breast cancer cell lines by the Caspase-3 activity assay. The application of these promoters may prove to have the advantage of tumor selective gene therapy in breast cancer cells and low-potential toxicity for normal tissues.

Cell selection and characterization of a novel human endothelial cell specific nanobody.

Antibody-based targeting of angiogenesis and vascular targeting therapy of cancer are extremely attractive conceptually and open new important diagnostic and therapeutic opportunities. Compelling evidence suggests that CD105 represents an ideal target for anti-angiogenic therapy and its presence in solid tumor vasculature has prognostic value. Camelids produce functional antibodies devoid of light chains and constant heavy chain domain (CH1). Nanobodies, the antigen-binding fragments of such heavy chain antibodies, are therefore comprised in one single domain. The aim of this study was to explore the possibilities of using anti-endoglin nanobody as an angiogenesis inhibitor. The anti-CD105 nanobody (AR-86a) was isolated from immune library by selections on purified antigens and target cells. Immunocytochemistry and FACS analysis showed that the purified nanobody reacted specifically with human umbilical vein endothelial cells (HUVECs) but not with other cell lines such as MDA-MB-453, Mel III, T-47D, MCF-7, AGO and HT 29. Further, selected nanobody potently inhibited proliferation of human endothelial cells and formation of capillary-like structures. This selected high affinity anti-endoglin nanobody may offer high specificity towards tumors with reduced side effects, and may be less likely to elicit drug resistance compared to conventional therapy.

Production and characterization of a high-affinity nanobody against human endoglin.

Abstract Antibodies or antibody fragments are almost exclusively applied in human therapy and diagnosis. The high affinity and specificity of antibodies makes them suitable for these applications. Nanobody, the variable domain of Camelidae heavy chain antibodies, have superior properties compared with conventional antibodies in that they are small, non-immunogenic, very stable, highly soluble, and easy to produce in large quantities. In the present study, we report the isolation and characterization of a high-affinity binder against human endoglin retrieved from camels' nanobody gene library. Endoglin (CD105), an accessory protein of the transforming growth factor beta receptor complex, has become an attractive molecule for the targeting of the tumor vasculature. Upregulation of endoglin on proliferating endothelial cells is associated with tumor neovascularization. Here, we generated two nanobody gene libraries displayed on phage particles. Some single-domain antibody fragments have been isolated that specifically recognize the recombinant extracellular domain of human endoglin. The other selected anti-endoglin nanobody (AR1-86) showed strong binding to human endoglin expressing endothelial cells (HUVECs), while no binding was observed with the endoglin-negative cell line (HEK293). This high-affinity single-domain antibody could be a good candidate for the generation of vascular or tumor targeting agents in cancer therapy.

Production and characterization of anti-(mucin MUC1) single-domain antibody in tobacco (Nicotiana tabacum cultivar Xanthi).

Members of the Camelidae (camels, dromedaries, llamas, alpacas, guanacos and vicunas) are known to produce Igs (immunoglobulins) devoid of light chains and CH1s (constant heavy-chain domains). The antigen-specific binding fragments of these heavy-chain antibodies therefore comprise one single domain (the so-called 'VHH') and are of great importance in biotechnological applications. To evaluate the expression and biological activity of sdAbs (single-domain antibodies) in plants, which, on account of their small size and antigen-recognition properties, would have a major impact on antibody-engineering strategies, we constructed a pBI121-VHH gene encoding the recombinant sdAb fragments with specificity for a cancer-associated mucin, MUC1. Analysis of transgenic tobacco (Nicotiana tabacum cultivar Xanthi) plants by PCR and Western blotting demonstrated the expression of sdAb, while ELISA results with various MUC1 antigens and immunocytochemistry with cancerous cell lines confirmed that the activity of these molecules compared favourably with that of the parent recombinant antibodies. Protein purification was achieved by using sequential (NH4)2SO4 precipitation, gel filtration and immunoaffinity chromatography. Analysis of the purified VHH by ELISA indicated that the purified antibody fragments were able to react successfully with a MUC1-related peptide. These results reaffirm that the tobacco plant is a suitable host for the production of correctly folded VHH antibody fragments with diagnostic and therapeutic applications.

A new competitive enzyme linked immunosorbent assay (MRP83-CA15-3) for MUC1 measurement in breast cancer.

A new competitive enzyme linked immunosorbent assay was developed in this study. Monoclonal antibody (PR81) against the tandem repeat of the core protein was prepared, characterized, purified, and conjugated to HRP. This antibody exhibited no cross reactions with proteins such as bovine serum albumin, keyhole limpet homocyanin, human serum albumin, casein, human milk fat globin (HMFG), and peptone. The native cancerous MUC1 protein was purified from ascites fluid of a patient suffering from small cell lung carcinoma by immunoaffinity chromatography and used as a standard preparation in the assay buffer. The standard curve was constructed following a competitive procedure in the range of 0-200 U/mL. The level of MUC1 in normal and cancerous samples was compared following this procedure and using available CA15-3 EIA (Can Ag), as well as LIAISON CA15-3 commercial kits. The correlation coefficient between the procedure reported in this work (MRP83-CA15-3) and CA15-3 EIA (Can Ag) was 0.68 and was 0.95 with the LIAISON CA15-3 kit. We concluded that the present assay can detect MUC1 in breast cancer patients with great sensitivity and accuracy.

Over expression of anti-MUC1 single-domain antibody fragments in the yeast Pichia pastoris.

The methylotrophic yeast Pichia pastoris has become a highly popular expression host system for the recombinant production of a wide variety of proteins, such as antibody fragments. Camelids produce functional antibodies devoid of light chains and constant heavy-chain domain (CH1). The antigen binding fragments of such heavy chain antibodies are therefore comprised in one single domain, the so-called VH of the camelid heavy chain antibody (VHH). To test the feasibility of expressing VHHs in the yeast, which on account of their small size and antigen recognition properties would have a major impact on antibody engineering strategies, we constructed two VHH genes encoding the single-domain antibody fragments with specificity for a cancer associated mucin, MUC1. The recombinant strains of the yeast P. pastoris were developed which secrete single-domain antibody fragment to the culture supernatant as a biologically active protein. Supplementation of medium with sorbitol (in pre-induction phase) and casamino acid or EDTA (in induction phase) provided ideal condition of increasing the yield of VHH production compared to culture condition devoid of above recipe. The secreted protein was purified following a 80% ammonium sulfate precipitation step, followed by a affinity chromatography column. The specific activity in enzyme-linked immunosorbant assay (ELISA) of the purified yeast VHH was higher than that of a bacterial periplasmic counterpart. These results reaffirm that the yeast P. pastoris is a suitable host for high level and correctly folded production of VHH antibody fragments with potential in vivo diagnostic and therapeutic applications. This is the first report of expression of VHH in P. pastoris.

The production and characterization of novel heavy-chain antibodies against the tandem repeat region of MUC1 mucin.

Camelidae are known to produce immunoglobulins (Igs) devoid of light chains and constant heavy-chain domains (CH1). Antigen-specific fragments of these heavy-chain IgGs (VHH) are of great interest in biotechnology applications. This paper describes the first example of successfully raised heavy-chain antibodies in Camelus dromedarius (single-humped camel) and Camelus bactrianus (two-humped camel) against a MUC1 related peptide that is found to be an important epitope expressed in cancerous tissue. Camels were immunized against a synthetic peptide corresponding to the tandem repeat region of MUC1 mucin and cancerous tissue preparation obtained from patients suffering from breast carcinoma. Three IgG subclasses with different binding properties to protein A and G were purified by affinity chromatography. Both conventional and heavy-chain IgG antibodies were produced in response to MUC1-related peptide. The elicited antibodies could react specifically with the tandem repeat region of MUC1 mucin in an enzyme linked immunosorbant assay (ELISA). Anti-peptide antibodies were purified after passing antiserum over two affinity chromatography columns. Using ELISA, immunocytochemistry and Western blotting, the interaction of purified antibodies with different antigens was evaluated. The antibodies were observed to be selectively bound to antigens namely: MUC1 peptide (tandem repeat region), human milk fat globule membrane (HMFG), deglycosylated human milk fat globule membrane (D-HMFG), homogenized cancerous breast tissue and a native MUC1 purified from ascitic fluid. Ka values of specific polyclonal antipeptide antibodies were estimated in C. dromedarius and C. bactrianus, as 7 x 10(10) M(-1) and 1.4 x 10(10) M(-1) respectively.

Stabilization of penicillinase-hapten conjugate for enzyme immunoassay.

The influence of various additives, such as organic solvents, polyhydric alcohols, salts, polymers, and cross-linker, on the stability and storage ability of penicillinase-morphine conjugate was studied in liquid and solid (freeze dried) states. The results of these experiments showed that using low concentrations of CaCl2 (0.1-0.2%) could stabilize enzyme activity in both states for more than seven months. The immunoreactivity of antigen toward the antibody did not change significantly. However, a cross-linker such as glutaraldehyde and various additives such as dimethylsulfoxide, glycerol, polyethylene glycol, gelatin, dextran, ammonium sulfate, lactose, and sucrose did not have any effect on stability. In addition, it was found that the presence of lactose and sucrose in the lyophilization procedure gives a significant amount of protection to the enzyme, which could last for a period of seven months and preserve almost 95% of the enzyme activity, as well as immunoreactivity of the tracer molecule.