Saponin Facilitates Anti-Robo1 Immunotoxin Cytotoxic Effects on Maxillary Sinus Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers worldwide. The standard treatment of surgery, chemotherapy, and radiotherapy can result in long-term complications which lower the patient’s quality of life, such as eating disorders, speech problems, and disfiguring or otherwise untoward cosmetic issues. Antibody therapy against cancer-specific antigens is advantageous in terms of its lesser side effects achieved by its greater specificity, though the antitumor activity is still usually not enough to obtain a complete cure. Robo1, an axon guidance receptor, has received considerable attention as a possible drug target in various cancers. We have shown previously the enhanced cytotoxic effects of saporin-conjugated anti-Robo1 immunotoxin (IT-Robo1) on the HNSCC cell line HSQ-89 in combination with a photochemical internalization technique. Considering the light source, which has only limited tissue penetrance, we examined the drug internalization effect of saponin. Treatment with saponin facilitated significant cytotoxic effects of IT-Robo1 on HSQ-89 cells. Saponin exerts its own nonspecific cytotoxicity, which may cover the actual extent of the internalization effect. We thus examined whether a flashed treatment with saponin exerted a significant specific cytotoxic effect on cancer cells. The combination of an immunotoxin with saponin also exhibited a significant tumor-suppressive effect on mice HSQ-19 xenografts. These results suggest the utility of saponin treatment as an enhancer of immunotoxin treatment in cancer.

Invasive fungal infections in the immunocompromised host: Mechanistic insights in an era of changing immunotherapeutics

The use of cytotoxic chemotherapy in the treatment of malignant and inflammatory disorders is beset by considerable adverse effects related to nonspecific cytotoxicity. Accordingly, a mechanistic approach to therapeutics has evolved in recent times with small molecular inhibitors of intracellular signaling pathways involved in disease pathogenesis being developed for clinical use, some with unparalleled efficacy and tolerability. Nevertheless, there are emerging concerns regarding an association with certain small molecular inhibitors and opportunistic infections, including invasive fungal diseases. This is perhaps unsurprising, given that the molecular targets of such agents play fundamental and multifaceted roles in orchestrating innate and adaptive immune responses. Nevertheless, some small molecular inhibitors appear to possess intrinsic antifungal activity and may therefore represent novel therapeutic options in future. This is particularly important given that antifungal resistance is a significant, emerging concern. This paper is a comprehensive review of the state-of-the-art in the molecular immunology to fungal pathogens as applied to existing and emerging small molecular inhibitors.

Biophysical, Biochemical, and Cell Based Approaches Used to Decipher the Role of Carbonic Anhydrases in Cancer and to Evaluate the Potency of Targeted Inhibitors

Carbonic anhydrases (CAs) are thought to be important for regulating pH in the tumor microenvironment. A few of the CA isoforms are upregulated in cancer cells, with only limited expression in normal cells. For these reasons, there is interest in developing inhibitors that target these tumor-associated CA isoforms, with increased efficacy but limited nonspecific cytotoxicity. Here we present some of the biophysical, biochemical, and cell based techniques and approaches that can be used to evaluate the potency of CA targeted inhibitors and decipher the role of CAs in tumorigenesis, cancer progression, and metastatic processes. These techniques include esterase activity assays, stop flow kinetics, and mass inlet mass spectroscopy (MIMS), all of which measure enzymatic activity of purified protein, in the presence or absence of inhibitors. Also discussed is the application of X-ray crystallography and Cryo-EM as well as other structure-based techniques and thermal shift assays to the studies of CA structure and function. Further, large-scale genomic and proteomic analytical methods, as well as cell based techniques like those that measure cell growth, apoptosis, clonogenicity, and cell migration and invasion, are discussed. We conclude by reviewing approaches that test the metastatic potential of CAs and how the aforementioned techniques have contributed to the field of CA cancer research.

Antibacterial and Antibiofilm Activities of a Novel Synthetic Cyclic Lipopeptide against Cariogenic Streptococcus mutans UA159

ABSTRACT Despite continuous efforts to control cariogenic dental biofilms, very few effective antimicrobial treatments exist. In this study, we characterized the activity of the novel synthetic cyclic lipopeptide 4 (CLP-4), derived from fusaricidin, against the cariogenic pathogen Streptococcus mutans UA159. We determined CLP-4's MIC, minimum bactericidal concentration (MBC), and spontaneous resistance frequency, and we performed time-kill assays. Additionally, we assessed CLP-4's potential to inhibit biofilm formation and eradicate preformed biofilms. Our results demonstrate that CLP-4 has strong antibacterial activity in vitro and is a potent bactericidal agent with low spontaneous resistance frequency. At a low concentration of 5 μg/ml, CLP-4 completely inhibited S. mutans UA159 biofilm formation, and at 50 μg/ml, it reduced the viability of established biofilms by >99.99%. We also assessed CLP-4's cytotoxicity and stability against proteolytic digestion. CLP-4 withstood trypsin or chymotrypsin digestion even after treatment for 24 h, and our toxicity studies showed that CLP-4 effective concentrations had negligible effects on hemolysis and the viability of human oral fibroblasts. In summary, our findings showed that CLP-4 is a potent antibacterial and antibiofilm agent with remarkable stability and low nonspecific cytotoxicity. Hence, CLP-4 is a promising novel antimicrobial peptide with potential for clinical application in the prevention and treatment of dental caries.

Engineered biomimetic nanoabsorbent for cellular detoxification of chemotherapeutics

An approach to reduce the nonspecific cytotoxicity of chemotherapeutics has been put-forth using a biomimetic nanoabsorbent (NAb) as a detoxifying agent.

FEATURES OF ANTIVIRAL IMMUNITY IN PATIENTS WITH DAMAGE TO THE AUTONOMIC ПАРАСИМПТИЧЕСКИХ NODES OF THE HEAD

<p>The immune status at 33 patients with defeat of vegetative parasympathetic knots of a virus etiology at the age from 27 till 64 years is investigated. From them the 19th woman and 15 men. The obtained data compared to indicators of healthy people. Patients addressed on neurostomatologic reception in versatile stomatologic policlinic of the Ural State Medical Academy on chair of surgical stomatology For the first time the structural analysis of a condition of various factors of antiviral protection is studied and carried out and the most significant disorders of immunity taking into account clinical data at patients with defeat of vegetative parasympathetic knots of a virus etiology are allocated, at the majority of patients immunological signs of a secondary immunoscarce condition with violations in humoral and cellular links of immunity, hyper reactance and insufficiency of systems of specific and nonspecific cytotoxicity.</p>

Targeted Alpha-Particle Immunotherapy with Bismuth-213 and Actinium-225 for Acute Myeloid Leukemia

ABSTRACT Lintuzumab, a humanized anti-CD33 antibody, targets myeloid leukemia cells and has modest activity against acute myeloid leukemia (AML). To increase the antibody's potency yet avoid nonspecific cytotoxicity seen with β-emitting isotopes, lintuzumab was conjugated to the α-emitters bismuth-213 (213Bi) and actinium-225 (225Ac). The 46-minute half-life of 213Bi limits its widespread use. Therefore, 225Ac was also conjugated to various antibodies using DOTA-SCN. We conducted a phase I trial of 213Bi-lintuzumab and subsequently administered cytarabine with 213Bi-lintuzumab in a phase I/II study. The toxicity and biological activity of 225Ac-linutuzumab in patients with relapsed/refractory AML in a phase I dose-escalation trial was determined. An initial phase I trial demonstrated the feasibility, safety and antileukemic activity of 213Bi-lintuzumab. 213Bi-lintuzumab produced responses in 24% of AML patients receiving doses ≥ 37 MBq/kg after partial cytoreduction with cytarabine. 225Ac-labeled immunoconjugates killed in vitro at doses at least 1,000 times lower than 213Bi analogs. Eighteen patients with relapsed/refractory AML received 18.5 to 148 kBq/kg of 225Ac-lintuzumab in a phase I study. Dose-limiting toxicities were myelosuppression lasting >35 days in one patient and death due to sepsis in two patients. The maximum tolerated dose (MTD) was 111 KBg/kg. Bone marrow blast reductions were seen across all dose levels. Targeted α- particle immunotherapy with 213Bi- and 225Ac-lintuzumab is safe, has significant antileukemic effects, and can produce remissions after partial cytoreduction. How to cite this article Jurcic JG. Targeted Alpha-Particle Immunotherapy with Bismuth-213 and Actinium-225 for Acute Myeloid Leukemia. J Postgrad Med Edu Res 2013;47(1): 14-17.

Evaluation of XL999, a Potent Inhibitor of FGFR3, for the Potential Treatment of t(4;14) Positive Multiple Myeloma.

Recent advances in our understanding of the molecular pathogenesis of Multiple Myeloma (MM) have provided novel therapeutic targets for treatment of this incurable malignancy. The association of Fibroblast Growth Factor Receptor 3 (FGFR3) with the t(4;14) translocation that occurs uniquely in approximately 15% of MM patients, coupled with the demonstration of the transforming potential of this receptor tyrosine kinase (RTK), make this a particularly attractive target for the development of therapeutic agents for this poor prognosis group. Indeed, inhibition of activated FGFR3 induces apoptosis and inhibits growth in mice of FGFR3-expressing MM tumors, providing further validation of this RTK as a therapeutic target in t(4;14) MM. XL999 is a novel small molecule inhibitor of kinases involved in tumor cell growth and angiogenesis, and is currently in a Phase 1 clinical trial in patients with non-small cell lung cancer. XL999 inhibits members of the class III-V RTKs, including FGFR1 and 3, VEGFR2, PDGFR? and ?, KIT, and FLT3, and exhibits pharmacodynamic target modulation, anti-angiogenesis, and efficacy in multiple tumor models in mice (Eur. J. Cancer Suppl. 2: 141). We report here the FGFR3-targeting characteristics and anti-myeloma activity of XL999. XL999 inhibits FGFR3 with low nanomolar potency in biochemical enzyme assays. Therefore, we examined the activity of XL999 in several cell-based mechanistic assays of FGFR3 activity. The IL-6 dependent cell line, B9, was engineered to express wild-type or activated mutants (Y373C, K650E, G384D and J807C) of FGFR3 found in MM. XL999 differentially inhibited FGF-mediated growth of B9 cells expressing wild-type and mutant receptors, with IC50 values in the low nM range. Growth of these cells could be rescued by IL-6, indicating selectivity of XL999 for FGFR3. The activity of XL999 against FGFR3 was also examined in t(4;14) positive MM cell lines expressing FGFR3. XL999 inhibited the proliferation and viability of KMS-11 cells (FGFR3-Y373C) and OPM-2 cells (expressing FGFR3-K650E) with low nM potency. Importantly, inhibition by XL999 was still observed in the presence of IL-6 or IGF1, potent growth factors for MM cells. In addition, XL999 potently inhibited the phosphorylation of FGFR3 in OPM-2 and KMS-11 tumors after a single oral dose in pharmacodynamic studies in nude mice. U266 and 8226 cells, which lack FGFR3 expression, displayed minimal growth inhibition by XL999, demonstrating that at effective concentrations, XL999 is selective and exhibits minimal nonspecific cytotoxicity to FGFR3 negative MM cells. Further characterization of this finding demonstrated that inhibition of cell growth corresponded to G0/G1 cell cycle arrest, dose-dependent inhibition of downstream ERK phosphorylation, and induction of apoptosis in FGFR3-positive cells. In vitro analysis of XL999 combined with melphalan, bortezomib, or dexamethasone applied simultaneously to KMS11 cells indicated a strong synergistic interaction with dexamethasone, and additivity with either melphalan or bortezomib. Finally, XL999 produced cytotoxic responses in 5/5 primary myeloma samples derived from patients harboring a t(4;14) translocation. Collectively, these results suggest that XL999 may hold potential for patients with MM, particularly in combination with other agents.

Structural Correlates of Antibacterial and Membrane-Permeabilizing Activities in Acylpolyamines

ABSTRACTA homologous series of mono- and bis-acyl polyamines with varying acyl chain lengths originally synthesized for the purpose of sequestering lipopolysaccharide were evaluated for antimicrobial activity to test the hypothesis that these bis-cationic amphipathic compounds may also bind to and permeabilize intact gram-negative bacterial membranes. Some compounds were found to possess significant antimicrobial activity, mediated via permeabilization of bacterial membranes. Structure-activity relationship studies revealed a strong dependence of the acyl chain length on antimicrobial potency and permeabilization activity. Homologated spermine, bis-acylated with C8or C9chains, was found to profoundly sensitizeEscherichia colito hydrophobic antibiotics such as rifampin. Nonspecific cytotoxicity is a potential drawback of these membranophilic compounds. However, the surface activity of these cationic amphipaths is strongly attenuated under physiological conditions via binding to serum albumin. Significant antibacterial activity is still retained in the presence of physiological concentrations of human serum albumin, suggesting that these compounds may serve as leads in the development of novel adjuncts to conventional antimicrobial chemotherapy.