Switchable CAR T cell strategy against osteosarcoma.

Immunotherapy with chimeric antigen receptor T (CAR T) cells has changed the treatment of hematological malignances, but they are still a challenge for solid tumors, including pediatric sarcomas. Here, we report a switchable CAR T cell strategy based on anti-FITC CAR T cells and a switch molecule conjugated with FITC for targeting osteosarcoma (OS) tumors. As a potential target, we analyzed the expression of B7-H3, an immune checkpoint inhibitor, in OS cell lines. In addition, we evaluate the capacity of an anti-B7-H3 monoclonal antibody conjugated with FITC (anti-B7-H3-FITC mAb) to control the antitumor activity of anti-FITC CAR T cells. The effector functions of anti-FITC CAR T cells against OS, measured in vitro by tumor cell killing activity and cytokine production, are dependent on the presence of the anti-B7-H3-FITC mAb switch. Moreover, OS cells stimulate anti-FITC CAR T cells migration. In vivo, anti-B7-H3 mAb penetrates in the tumor and binds 143B OS tumor cells. Furthermore, anti-FITC CAR T cells reach tumor region and exert antitumor effect in an OS NSG mouse model only in the presence of the switch molecule. We demonstrate that anti-B7-H3-FITC mAb redirects the cytotoxic activity of anti-FITC CAR T cells against OS tumors suggesting that switchable CAR T cell platforms might be a plausible strategy against OS.

Lamin A/C and the Immune System: One Intermediate Filament, Many Faces.

Nuclear envelope lamin A/C proteins are a major component of the mammalian nuclear lamina, a dense fibrous protein meshwork located in the nuclear interior. Lamin A/C proteins regulate nuclear mechanics and structure and control cellular signaling, gene transcription, epigenetic regulation, cell cycle progression, cell differentiation, and cell migration. The immune system is composed of the innate and adaptive branches. Innate immunity is mediated by myeloid cells such as neutrophils, macrophages, and dendritic cells. These cells produce a rapid and nonspecific response through phagocytosis, cytokine production, and complement activation, as well as activating adaptive immunity. Specific adaptive immunity is activated by antigen presentation by antigen presenting cells (APCs) and the cytokine microenvironment, and is mainly mediated by the cellular functions of T cells and the production of antibodies by B cells. Unlike most cell types, immune cells regulate their lamin A/C protein expression relatively rapidly to exert their functions, with expression increasing in macrophages, reducing in neutrophils, and increasing transiently in T cells. In this review, we discuss and summarize studies that have addressed the role played by lamin A/C in the functions of innate and adaptive immune cells in the context of human inflammatory and autoimmune diseases, pathogen infections, and cancer.

From Ugi Multicomponent Reaction to Linkers for Bioconjugation.

Bioconjugation is a key approach for the development of novel molecular entities with clinical applications. The biocompatibility and specificity of biomolecules such as peptides, proteins, and antibodies make these macromolecules ideal carriers for selective targeted therapies. In this context, there is a need to develop new molecular units that cover the requirements of the next generation of targeted pharmaceuticals. Here, we present the design and development of a versatile and stable linker based on a N-alkylated α,α-dialkyl dipeptide for bioconjugation, with a particular focus on antibody-drug conjugates (ADCs). Starting with the well-known Ugi multicomponent reaction, the convenient chemical modification of the prepared adducts allowed us the obtention of versatile bifunctional linkers for bioconjugation. A conjugation strategy was tested to demonstrate the efficiency of the linker. In addition, a novel cytotoxic anti-HER2 ADC was prepared using the Ugi-linker approach.

CD13 as a new tumor target for antibody-drug conjugates: validation with the conjugate MI130110.

BACKGROUND: In the search for novel antibody-drug conjugates (ADCs) with therapeutic potential, it is imperative to identify novel targets to direct the antibody moiety. CD13 seems an attractive ADC target as it shows a differential pattern of expression in a variety of tumors and cell lines and it is internalized upon engagement with a suitable monoclonal antibody. PM050489 is a marine cytotoxic compound tightly binding tubulin and impairing microtubule dynamics which is currently undergoing clinical trials for solid tumors. METHODS: Anti-CD13 monoclonal antibody (mAb) TEA1/8 has been used to prepare a novel ADC, MI130110, by conjugation to the marine compound PM050489. In vitro and in vivo experiments have been carried out to demonstrate the activity and specificity of MI130110. RESULTS: CD13 is readily internalized upon TEA1/8 mAb binding, and the conjugation with PM050489 did not have any effect on the binding or the internalization of the antibody. MI130110 showed remarkable activity and selectivity in vitro on CD13-expressing tumor cells causing the same effects than those described for PM050489, including cell cycle arrest at G2, mitosis with disarrayed and often multipolar spindles consistent with an arrest at metaphase, and induction of cell death. In contrast, none of these toxic effects were observed in CD13-null cell lines incubated with MI130110. Furthermore, in vivo studies showed that MI130110 exhibited excellent antitumor activity in a CD13-positive fibrosarcoma xenograft murine model, with total remissions in a significant number of the treated animals. Mitotic catastrophes, typical of the payload mechanism of action, were also observed in the tumor cells isolated from mice treated with MI130110. In contrast, MI130110 failed to show any activity in a xenograft mouse model of myeloma cells not expressing CD13, thereby corroborating the selectivity of the ADC to its target and its stability in circulation. CONCLUSION: Our results show that MI130110 ADC combines the antitumor potential of the PM050489 payload with the selectivity of the TEA1/8 monoclonal anti-CD13 antibody and confirm the correct intracellular processing of the ADC. These results demonstrate the suitability of CD13 as a novel ADC target and the effectiveness of MI130110 as a promising antitumor therapeutic agent.

Immunobiology of Atherosclerosis: A Complex Net of Interactions.

Cardiovascular disease is the leading cause of mortality worldwide, and atherosclerosis the principal factor underlying cardiovascular events. Atherosclerosis is a chronic inflammatory disease characterized by endothelial dysfunction, intimal lipid deposition, smooth muscle cell proliferation, cell apoptosis and necrosis, and local and systemic inflammation, involving key contributions to from innate and adaptive immunity. The balance between proatherogenic inflammatory and atheroprotective anti-inflammatory responses is modulated by a complex network of interactions among vascular components and immune cells, including monocytes, macrophages, dendritic cells, and T, B, and foam cells; these interactions modulate the further progression and stability of the atherosclerotic lesion. In this review, we take a global perspective on existing knowledge about the pathogenesis of immune responses in the atherosclerotic microenvironment and the interplay between the major innate and adaptive immune factors in atherosclerosis. Studies such as this are the basis for the development of new therapies against atherosclerosis.

92R Monoclonal Antibody Inhibits Human CCR9+ Leukemia Cells Growth in NSG Mice Xenografts.

CCR9 is as an interesting target for the treatment of human CCR9+-T cell acute lymphoblastic leukemia, since its expression is limited to immature cells in the thymus, infiltrating leukocytes in the small intestine and a small fraction of mature circulating T lymphocytes. 92R, a new mouse mAb (IgG2a isotype), was raised using the A-isoform of hCCR9 as immunogen. Its initial characterization demonstrates that binds with high affinity to the CCR9 N-terminal domain, competing with the previously described 91R mAb for receptor binding. 92R inhibits human CCR9+ tumor growth in T and B-cell deficient Rag2-/- mice. In vitro assays suggested complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity as possible in vivo mechanisms of action. Unexpectedly, 92R strongly inhibited tumor growth also in a model with compromised NK and complement activities, suggesting that other mechanisms, including phagocytosis or apoptosis, might also be playing a role on 92R-mediated tumor elimination. Taken together, these data contribute to strengthen the hypothesis of the immune system's opportunistic nature.

Bioconjugation through Mesitylene Thiol Alkylation.

The design and generation of complex multifunctional macromolecular structures by bioconjugation is a hot topic due to increasing interest in conjugates with therapeutic applications. In this regard, the development of efficient, selective, and safe conjugation methods is a major objective. In this report, we describe the use of the bis(bromomethyl)benzene scaffold as a linker for bioconjugation with special emphasis on antibody conjugation. We first performed the monothioalkylation of 1,3,5-tris(bromomethyl)benzene, which rendered the reactive dibromotrimethylbenzyl derivatives to be used in thiol bis-alkylation. Next, we introduced into the linker either a bis(Cys)-containing peptide or anti-CD4 and -CD13 monoclonal antibodies, previously subjected to partial reduction of disulfide bonds. Mass spectrometry, UV-vis spectra, and SDS-PAGE experiments revealed that this bis-alkylating agent for bioconjugation preserved both antibody integrity and antibody-antigen binding affinity, as assessed by flow cytometry. Taken together, our results show that the mesitylene scaffold is a suitable linker for thiol-based bioconjugation reactions. This linker could be applicable in the near future for the preparation of antibody drug conjugates.

New Strategies Using Antibody Combinations to Increase Cancer Treatment Effectiveness.

Antibodies have proven their high value in antitumor therapy over the last two decades. They are currently being used as the first-choice to treat some of the most frequent metastatic cancers, like HER2+ breast cancers or colorectal cancers, currently treated with trastuzumab (Herceptin) and bevacizumab (Avastin), respectively. The impressive therapeutic success of antibodies inhibiting immune checkpoints has extended the use of therapeutic antibodies to previously unanticipated tumor types. These anti-immune checkpoint antibodies allowed the cure of patients devoid of other therapeutic options, through the recovery of the patient's own immune response against the tumor. In this review, we describe how the antibody-based therapies will evolve, including the use of antibodies in combinations, their main characteristics, advantages, and how they could contribute to significantly increase the chances of success in cancer therapy. Indeed, novel combinations will consist of mixtures of antibodies against either different epitopes of the same molecule or different targets on the same tumor cell; bispecific or multispecific antibodies able of simultaneously binding tumor cells, immune cells or extracellular molecules; immunomodulatory antibodies; antibody-based molecules, including fusion proteins between a ligand or a receptor domain and the IgG Fab or Fc fragments; autologous or heterologous cells; and different formats of vaccines. Through complementary mechanisms of action, these combinations could contribute to elude the current limitations of a single antibody which recognizes only one particular epitope. These combinations may allow the simultaneous attack of the cancer cells by using the help of the own immune cells and exerting wider therapeutic effects, based on a more specific, fast, and robust response, trying to mimic the action of the immune system.

Monoclonal Antibody Therapies for Hematological Malignancies: Not Just Lineage-Specific Targets.

Today, monoclonal antibodies (mAbs) are a widespread and necessary tool for biomedical science. In the hematological cancer field, since rituximab became the first mAb approved by the Food and Drug Administration for the treatment of B-cell malignancies, a number of effective mAbs targeting lineage-specific antigens (LSAs) have been successfully developed. Non-LSAs (NLSAs) are molecules that are not restricted to specific leukocyte subsets or tissues but play relevant pathogenic roles in blood cancers including the development, proliferation, survival, and refractoriness to therapy of tumor cells. In consequence, efforts to target NLSAs have resulted in a plethora of mAbs-marketed or in development-to achieve different goals like neutralizing oncogenic pathways, blocking tumor-related chemotactic pathways, mobilizing malignant cells from tumor microenvironment to peripheral blood, modulating immune-checkpoints, or delivering cytotoxic drugs into tumor cells. Here, we extensively review several novel mAbs directed against NLSAs undergoing clinical evaluation for treating hematological malignancies. The review focuses on the structure of these antibodies, proposed mechanisms of action, efficacy and safety profile in clinical studies, and their potential applications in the treatment of hematological malignancies.

Indole-3-Carbinol Synergizes with and Restores Fludarabine Sensitivity in Chronic Lymphocytic Leukemia Cells Irrespective of p53 Activity and Treatment Resistances.

PURPOSE: Chronic lymphocytic leukemia (CLL) still is lacking a cure. Relapse and development of refractoriness to current treatments are common. New therapies are needed to improve patient prognosis and survival. EXPERIMENTAL DESIGN: Indole-3-carbinol (I3C) is a natural product with antitumor properties already clinically tested. The effect of I3C, F-ara-A, and combinations of both drugs on CLL cells from patients representing different Rai stages, IGHV mutation status, cytogenetic alterations, p53 functionality, and treatment resistances was tested, as well as the toxicity of these treatments in mice. RESULTS: I3C induces cytotoxicity in CLL cells but not in normal lymphocytes. I3C strongly synergized with F-ara-A in all CLL cells tested, including those with p53 deficiency and/or F-ara-A resistance. The mechanism of cell death involved p53-dependent and -independent apoptosis. The combination of I3C + F-ara-A was equally effective in CLL cells irrespective of IGHV mutation stage and patient refractoriness. Moreover, CLL survival and treatment resistance induced by co-culturing CLL cells on stroma cells were overcome by the combinatory I3C + F-ara-A treatment. No toxicity was associated with the combined I3C + fludarabine treatment in mice. CONCLUSIONS: I3C in combination with F-ara-A is highly cytotoxic in CLL cells from refractory patients and those with p53 deficiency. The striking dose reduction index for F-ara-A in combination with I3C would reduce fludarabine toxicity while having a similar or better anti-CLL effectiveness. Moreover, the low toxicity of I3C, already clinically tested, supports its use as adjuvant and combinatory therapy in CLL, particularly for patients with relapsed or refractory disease.

Anti-CCR7 therapy exerts a potent anti-tumor activity in a xenograft model of human mantle cell lymphoma.

BACKGROUND: The chemokine receptor CCR7 mediates lymphoid dissemination of many cancers, including lymphomas and epithelial carcinomas, thus representing an attractive therapeutic target. Previous results have highlighted the potential of the anti-CCR7 monoclonal antibodies to inhibit migration in transwell assays. The present study aimed to evaluate the in vivo therapeutic efficacy of an anti-CCR7 antibody in a xenografted human mantle cell lymphoma model. METHODS: NOD/SCID mice were either subcutaneously or intravenously inoculated with Granta-519 cells, a human cell line derived from a leukemic mantle cell lymphoma. The anti-CCR7 mAb treatment (3 × 200 µg) was started on day 2 or 7 to target lymphoma cells in either a peri-implantation or a post-implantation stage, respectively. RESULTS: The anti-CCR7 therapy significantly delayed the tumor appearance and also reduced the volumes of tumors in the subcutaneous model. Moreover, an increased number of apoptotic tumor cells was detected in mice treated with the anti-CCR7 mAb compared to the untreated animals. In addition, significantly reduced number of Granta-519 cells migrated from subcutaneous tumors to distant lymphoid organs, such as bone marrow and spleen in the anti-CCR7 treated mice. In the intravenous models, the anti-CCR7 mAb drastically increased survival of the mice. Accordingly, dissemination and infiltration of tumor cells in lymphoid and non-lymphoid organs, including lungs and central nervous system, was almost abrogated. CONCLUSIONS: The anti-CCR7 mAb exerts a potent anti-tumor activity and might represent an interesting therapeutic alternative to conventional therapies.