Highly sensitive detection of CTLA-4-positive T-cell subgroups based on nanobody and fluorescent carbon quantum dots

A novel doxorubicin/CTLA-4 blocker co-loaded drug delivery system improves efficacy and safety in antitumor therapy

Doxorubicin's antitumor effectiveness may be constrained with ineffective tumor penetration, systemic adverse effects, as well as drug resistance. The co-loading of immune checkpoint inhibitors and doxorubicin into liposomes can produce synergistic benefits and address problems, including quick drug clearance, toxicity, and low drug penetration efficiency. In our previous study, we modified a nanobody targeting CTLA-4 onto liposomes (LPS-Nb36) to be an extremely potent CTLA-4 signal blocker which improve the CD8+ T-cell activity against tumors under physiological conditions. In this study, we designed a drug delivery system (LPS-RGD-Nb36-DOX) based on LPS-Nb36 that realized the doxorubicin and anti-CTLA-4 Nb co-loaded and RGD modification, and was applied to antitumor therapy. We tested whether LPS-RGD-Nb36-DOX could targets the tumor by in vivo animal photography, and more importantly, promote cytotoxic T cells proliferation, pro-inflammatory cytokine production, and cytotoxicity. Our findings demonstrated that the combination of activated CD8+ T cells with doxorubicin/anti-CTLA-4 Nb co-loaded liposomes can effectively eradicate tumor cells both in vivo and in vitro. This combination therapy is anticipated to have synergistic antitumor effects. More importantly, it has the potential to reduce the dose of chemotherapeutic drugs and improve safety.

A novel CTLA-4 blocking strategy based on nanobody enhances the activity of dendritic cell vaccine-stimulated antitumor cytotoxic T lymphocytes

Despite the great success of CTLA-4 blocking in cancer treatment, the use of anti-CTLA-4 monoclonal antibodies still faces many limitations. Now, immune checkpoint blocking coupled with adoptive cell therapy is gaining much attention. In this paper, we reported a strategy on the basis of anti-CTLA-4 nanobody (Nb)-modified liposomes to improve these obstacles. An Nb36/liposome complex was constructed and utilized as a blocker of the CTLA-4/B7 signal pathway in a combination with dendritic cell (DC)/tumor fusion vaccine to enhance the CD8+ T cell cytokine secretion, activation, proliferation, as well as specific cytotoxicity. Moreover, the CD8+ T cells induced by LPS-Nb36 and DC/tumor fusion vaccine led to higher CD8+ T cell effector function in vivo, which significantly retarded tumor growth and lengthened survival of tumor-bearing mice (HepG2, A549, and MGC-803). Our data demonstrate that the anti-CTLA-4 Nb-modified liposomes in connection with DC/tumor fusion vaccines enhance the CD8+ T cell antitumor activity in vitro and in vivo, and is expected to be an alternative therapy for patients with malignancies that have T cell dysfunction or have poor treatment against anti-CTLA-4 mAb.

Generation and Characterization of a Nanobody Against SARS-CoV

The sudden emergence of severe acute respiratory syndrome coronavirus (SARS-CoV) has caused global panic in 2003, and the risk of SARS-CoV outbreak still exists. However, no specific antiviral drug or vaccine is available; thus, the development of therapeutic antibodies against SARS-CoV is needed. In this study, a nanobody phage-displayed library was constructed from peripheral blood mononuclear cells of alpacas immunized with the recombinant receptor-binding domain (RBD) of SARS-CoV. Four positive clones were selected after four rounds of bio-panning and subjected to recombinant expression in E. coli. Further biological identification demonstrated that one of the nanobodies, S14, showed high affinity to SARS-CoV RBD and potent neutralization activity at the picomole level against SARS-CoV pseudovirus. A competitive inhibition assay showed that S14 blocked the binding of SARS-CoV RBD to either soluble or cell-expressed angiotensin-converting enzyme 2 (ACE2). In summary, we developed a novel nanobody targeting SARS-CoV RBD, which might be useful for the development of therapeutics against SARS.

Nanobodies for Medical Imaging: About Ready for Prime Time?

Recent advances in medical treatments have been revolutionary in shaping the management and treatment landscape of patients, notably cancer patients. Over the last decade, patients with diverse forms of locally advanced or metastatic cancer, such as melanoma, lung cancers, and many blood-borne malignancies, have seen their life expectancies increasing significantly. Notwithstanding these encouraging results, the present-day struggle with these treatments concerns patients who remain largely unresponsive, as well as those who experience severely toxic side effects. Gaining deeper insight into the cellular and molecular mechanisms underlying these variable responses will bring us closer to developing more effective therapeutics. To assess these mechanisms, non-invasive imaging techniques provide valuable whole-body information with precise targeting. An example of such is immuno-PET (Positron Emission Tomography), which employs radiolabeled antibodies to detect specific molecules of interest. Nanobodies, as the smallest derived antibody fragments, boast ideal characteristics for this purpose and have thus been used extensively in preclinical models and, more recently, in clinical early-stage studies as well. Their merit stems from their high affinity and specificity towards a target, among other factors. Furthermore, their small size (~14 kDa) allows them to easily disperse through the bloodstream and reach tissues in a reliable and uniform manner. In this review, we will discuss the powerful imaging potential of nanobodies, primarily through the lens of imaging malignant tumors but also touching upon their capability to image a broader variety of nonmalignant diseases.

Nanobodies targeting immune checkpoint molecules for tumor immunotherapy and immunoimaging (Review)

The immune checkpoint blockade is an effective strategy to enhance the anti-tumor T cell effector activity, thus becoming one of the most promising immunotherapeutic strategies in the history of cancer treatment. Several immune checkpoint inhibitor have been approved by the FDA, such as anti-CTLA-4, anti-PD-1, anti-PD-L1 monoclonal antibodies. Most tumor patients benefitted from these antibodies, but some of the patients did not respond to them. To increase the effectiveness of immunotherapy, including immune checkpoint blockade therapies, miniaturization of antibodies has been introduced. A single-domain antibody, also known as nanobody, is an attractive reagent for immunotherapy and immunoimaging thanks to its unique structural characteristic consisting of a variable region of a single heavy chain antibody. This structure confers to the nanobody a light molecular weight, making it smaller than conventional antibodies, although remaining able to bind to a specific antigen. Therefore, this review summarizes the production of nanobodies targeting immune checkpoint molecules and the application of nanobodies targeting immune checkpoint molecules in immunotherapy and immunoimaging.

Nanobodies: Next Generation of Cancer Diagnostics and Therapeutics

The development of targeted medicine has greatly expanded treatment options and spurred new research avenues in cancer therapeutics, with monoclonal antibodies (mAbs) emerging as a prevalent treatment in recent years. With mixed clinical success, mAbs still hold significant shortcomings, as they possess limited tumor penetration, high manufacturing costs, and the potential to develop therapeutic resistance. However, the recent discovery of “nanobodies,” the smallest-known functional antibody fragment, has demonstrated significant translational potential in preclinical and clinical studies. This review highlights their various applications in cancer and analyzes their trajectory toward their translation into the clinic.

Engineering Bacillus subtilis as a Versatile and Stable Platform for Production of Nanobodies

There is a growing need for a highly stable system to allow the production of biologics for diagnoses and therapeutic interventions on demand that could be used in extreme environments. Among the variety of biologics, nanobodies (Nbs) derived from single-chain variable antibody fragments from camelids have attracted great attention in recent years due to their small size and great stability with translational potentials in whole-body imaging and the development of new drugs. Intracellular expression using the bacterium Escherichia coli has been the predominant system to produce Nbs, and this requires lengthy steps for releasing intracellular proteins for purification as well as removal of endotoxins. Lyophilized, translationally competent cell extracts have also been explored as offering portability and long shelf life, but such extracts may be difficult to scale up and suffer from batch-to-batch variability. To address these problems, we present a new system to do the following: (i) engineer the spore-forming bacterium Bacillus subtilis to secrete Nbs that can target small molecules or protein antigens on mammalian cells, (ii) immobilize Nbs containing a cellulose-binding domain on a cellulose matrix for long-term storage and small-molecule capturing, (iii) directly use Nb-containing bacterial supernatant fluid to perform protein detection on cell surfaces, and (iv) convert engineered B. subtilis to spores that are resistant to most environmental extremes. In summary, our work may open a new paradigm for using B. subtilis as an extremely stable microbial factory to produce Nbs with applications in extreme environments on demand.IMPORTANCE It is highly desirable to produce biologics for diagnoses and therapeutic interventions on demand that could be used in a variety of settings. Among the many biologics, Nbs have attracted attention due to their small size, thermal stability, and broad utility in diagnoses, therapies, and fundamental research. Nbs originate from antibodies found in camelids, and >10 companies have invested in Nbs as potential drugs. Here, we present a system using cells of the bacterium Bacillus subtilis as a versatile platform for production of Nbs and then antigen detection via customized affinity columns. Importantly, B. subtilis carrying engineered genes for Nbs can form spores, which survive for years in a desiccated state. However, upon rehydration and exposure to nutrients, spores rapidly transition to growing cells which secrete encoded Nbs, thus allowing their manufacture and purification.