Targeting pan-essential pathways in cancer with cytotoxic chemotherapy: challenges and opportunities

Cytotoxic chemotherapy remains a key modality in cancer treatment. These therapies, successfully used for decades, continue to transform the lives of cancer patients daily. With the high attrition rate of current oncology drug development, combined with the knowledge that most new therapies do not displace standard-of-care treatments and that many healthcare systems cannot afford these new therapies; cytotoxic chemotherapies will remain an important component of cancer therapy for many years to come. The clinical value of these therapies is often under-appreciated within the pre-clinical cancer research community, where this diverse class of agents are often grouped together as non-specific cellular poisons killing tumor cells based solely upon proliferation rate; however, this is inaccurate. This review article seeks to reaffirm the importance of focusing research efforts upon improving our basic understanding of how these drugs work, discussing their ability to target pan-essential pathways in cancer cells, the relationship of this to the chemotherapeutic window, and highlighting basic science approaches that can be employed towards refining their use.

Liposomal Irinotecan Shows a Larger Therapeutic Index than Non-liposomal Irinotecan in Patient-Derived Xenograft Models of Pancreatic Cancer

INTRODUCTION

Liposomal irinotecan promotes controlled sustained release of irinotecan (CPT-11), therefore, we hypothesize that the therapeutic index (quantitative measurement of the relative efficacy/safety ratio of a drug) will be higher for liposomal than non-liposomal irinotecan.

METHODS

We compared the therapeutic indexes of liposomal and non-liposomal irinotecan in mice bearing subcutaneous patient-derived xenograft (PDX) pancreatic tumors under dosing regimens approximating the clinical setting. Following preliminary drug sensitivity/antitumor activity analyses on three PDX tumor models, one model was selected for analyses of efficacy, biomarker, toxicology, pharmacokinetics in mice receiving liposomal irinotecan (2.5, 10, 50 mg/kg/week) or non-liposomal irinotecan (10, 25, 50 mg/kg/week). The maximum tolerated dose (MTD) for each treatment was 50 mg/kg/week.

RESULTS

Using the selected IM-PAN-001 model at the MTD (both treatments, 50 mg/kg/week), antitumor activity, phospho-histone gamma-H2AX protein staining in cancer cell nuclei, histological tumor regression, and plasma levels of CPT-11 and its active metabolite SN-38 after 24 h were greater with liposomal than non-liposomal irinotecan, but tumor SN-38 levels were similar. At the lowest doses assessed, antitumor activity, histological tumor regression, and jejunum and bone marrow toxicity were similar. Based on these findings, liposomal and non-liposomal irinotecan had therapeutic indexes of 20 and 5, respectively.

CONCLUSION

This non-clinical study showed a fourfold broader therapeutic index with liposomal than non-liposomal irinotecan in mice bearing IM-PAN-001 PDX pancreatic tumors, even at optimal dosing for the two drugs. These findings support the clinical benefit observed with liposomal irinotecan in patients with pancreatic cancer.

Application of ablative therapy for intrahepatic recurrent hepatocellular carcinoma following hepatectomy

The post-hepatectomy recurrence rate of hepatocellular carcinoma (HCC) is persistently high, affecting the prognosis of patients. An effective therapeutic option is crucial for achieving long-term survival in patients with postoperative recurrences. Local ablative therapy has been established as a treatment option for resectable and unresectable HCCs, and it is also a feasible approach for recurrent HCC (RHCC) due to less trauma, shorter operation times, fewer complications, and faster recovery. This review focused on ablation techniques, description of potential candidates, and therapeutic and prognostic implications of ablation for guiding its application in treating intrahepatic RHCC.

Clinical Advantage of Attaining Index-Based Remission Prior to Composite Remission in Treating Rheumatoid Arthritis

BACKGROUND AND OBJECTIVES

The clinical advantage of targeting index-based remission prior to Boolean remission was evaluated retrospectively.

MATERIALS AND METHODS

A total of 578 patients with rheumatoid arthritis (RA), who were treated for more than three years, were recruited. Patients who were treated to targeted index-based remission and composite measure remission criteria such as Boolean remission from the first consultation were divided according to the turn of attaining Boolean remission and index-based remission: G-IBR, a group that matched index-based remission at the same time Boolean remission is attained or earlier; G-BR_IF, a group that attained Boolean remission followed by index-based remission or failed; G-IR_BF, a group that could not attain Boolean remission despite attaining index-based remission; G-BothF, a group that failed to attain either Boolean remission or index-based remission. Background factors were statistically compared among groups. The Boolean remission rate in patients who attained index-based remission (BRR) and the rate of failure to attain index-based remission in patients who failed to attain Boolean remission (BFR) were statistically evaluated.

RESULTS

Groups comprising 225, 231, and 482 in G-IBR; 160, 154, and 8 in G-BR_IF; 18, 18, and 75 in G-IR_BF; and 175, 175, and 13 in G-BothF when indexing the clinical disease activity index (CDAI), simplified disease activity index (SDAI), and 28-joints disease activity score with C-reactive protein (DAS28-CRP), respectively. Disease activity indices' scores after Boolean remission were demonstrated to be significantly higher in the G-BR_IF group than in the G-IBR group. BRR was 92.6%, 92.8%, and 86.5%, while BFR was 71.3%, 71.3%, and 13.8% when indexing CDAI, SDAI, and DAS28-CRP, respectively.

CONCLUSIONS

Targeting CDAI and SDAI remission prior to Boolean remission contributes to a stable clinical course.

Comparison of long-term outcomes after robotic versus laparoscopic radical gastrectomy: a propensity score-matching study

OBJECTIVE

There is insufficient evidence to evaluate the long-term outcomes of robotic radical gastrectomy. The aim of this study was to compare the radical results and long-term outcomes of robotic and laparoscopic radical gastrectomy.

METHODS

We prospectively collected and retrospectively analyzed the general clinicopathological data of gastric cancer patients treated with robotic radical gastrectomy (RG) and laparoscopic radical gastrectomy (LG) from July 2016 to July 2018 at Fujian Medical University Union Hospital. The RG cohort was matched 1:3 with the LG cohort by using propensity score matching (PSM). The primary endpoints of the study were 3-year overall survival (OS) and 3-year relapse-free survival (RFS).

RESULTS

The study included 221 patients treated with RG and 1106 patients treated with LG for gastric cancer. After PSM, 211 patients were included in the RG cohort, and 663 patients were included in the LG cohort. The 3-year OS rate was 81.0% in the robotic cohort and 79.3% in the laparoscopic cohort (log-rank test, P = 0.516). The 3-year RFS rate was 78.7% in the robotic cohort and 75.6% in the laparoscopic cohort (log-rank test, P = 0.600). In the subgroup analyses, no significant differences were noted between the RG and LG cohorts in terms of 3-year OS and 3-year RFS (all P > 0.05). The therapeutic value index of each lymph node station dissection in the robotic cohort was comparable to that in the laparoscopic cohort.

CONCLUSION

Robotic radical gastrectomy can achieve radical results and long-term outcomes comparable to laparoscopic surgery, and further multicenter prospective studies can be conducted to assess the clinical efficacy of robotic radical gastrectomy.

Fast killing kinetics, significant therapeutic index, and high stability of melittin-derived antimicrobial peptide

The emergence of multidrug-resistant (MDR) bacteria is a major challenge for antimicrobial chemotherapy. Concerning this issue, antimicrobial peptides (AMPs) have been presented as novel promising antibiotics. Our previous de novo designed melittin-derived peptides (MDP1 and MDP2) indicated their potential as peptide drug leads. Accordingly, this study was aimed to evaluate the kinetics of activity, toxicity, and stability of MDP1 and MDP2 as well as determination of their structures. The killing kinetics of MDP1 and MDP2 demonstrate that all bacterial strains were rapidly killed. MDP1 and MDP2 were ca. 100- and 26.6-fold less hemolytic than melittin and found to be respectively 72.9- and 41.6-fold less cytotoxic than melittin on the HEK293 cell line. MDP1 and MDP2 showed 252- and 132-fold improvement in their therapeutic index in comparison to melittin. MDP1 and MDP2 sustained their activities in the presence of human plasma and were found to be ca. four to eightfold more stable than melittin. Spectropolarimetry analysis of MDP1 and MDP2 indicates that the peptides adopt an alpha-helical structure predominantly. According to the fast killing kinetics, significant therapeutic index, and high stability of MDP1, it could be considered as a drug lead in a mouse model of septicemia infections.

The importance of plasma protein and tissue binding in a drug discovery program to successfully deliver a preclinical candidate

Plasma protein binding and tissue binding are arguably two of the most critical parameters that are measured as part of a drug discovery program since, according to the free drug hypothesis, it is the free drug that is responsible for both efficacy and toxicity. This chapter aims to deconstruct the role of plasma protein and tissue binding in drug discovery programs, and to consider the conclusion made by Pfizer and Genentech/Depomed a decade ago that optimising plasma protein binding as an independent parameter does not significantly influence efficacy. This chapter will also examine how binding metrics are applied in drug discovery programs and explore circumstances where optimising plasma protein or tissue binding can be an effective strategy to deliver a candidate molecule for preclinical development with an early indication of sufficient therapeutic index.

Biowaiver Monograph for Immediate-Release Solid Oral Dosage Forms: Sitagliptin Phosphate Monohydrate

Sitagliptin is an antihyperglycemic drug used in adults for the treatment of diabetes Type 2. Literature data and in-house experiments were applied in this monograph to assess whether methods based on the Biopharmaceutics Classification System (BCS) could be used to assess the bioequivalence of solid immediate-release (IR) oral dosage forms containing sitagliptin phosphate monohydrate, as an alternative to a pharmacokinetic study in human volunteers. The solubility and permeability characteristics of sitagliptin were reviewed according to the BCS, along with dissolution, therapeutic index, therapeutic applications, pharmacokinetics, pharmacodynamic characteristics, reports of bioequivalence (BE) / bioavailability problems, data on interactions between the drug and excipients and other data germane to the subject. All data reviewed in this monograph unambiguously support classification of sitagliptin as a BCS Class 1 drug. In light of its broad therapeutic index and lack of severe adverse effects, the clinical risks associated with moderately supraoptimal doses were deemed inconsequential, as were the risks associated with moderately suboptimal doses. Taking all evidence into consideration, it was concluded that the BCS-based biowaiver can be implemented for solid IR oral drug products containing sitagliptin phosphate monohydrate, provided (a) the test product is formulated solely with excipients commonly present in solid IR oral drug products approved in ICH or associated countries and used in amounts commonly applied in this type of product, (b) data in support of the BCS-based biowaiver are obtained using the methods recommended by the WHO, FDA, EMA or ICH and (c) the test product and the comparator product (which is the innovator product in this case) meet all in vitro dissolution specifications provided in the WHO, FDA, EMA or ICH guidance.

Scoping Review and Commentary on Prognostication for Patients with Intracerebral Hemorrhage with Advances in Surgical Techniques

INTRODUCTION

The intracerebral hemorrhage (ICH) score provides an estimate of 30-day mortality for patients with intracerebral hemorrhage in order to guide research protocols and clinical decision making. Several variations of such scoring systems have attempted to optimize its prognostic value. More recently, minimally invasive surgical techniques are increasingly being used with promising results. As more patients become candidates for surgical intervention, there is a need to re-discuss the best methods for predicting outcomes with or without surgical intervention.

METHODS

We systematically performed a scoping review with a comprehensive literature search by two independent reviewers using the PubMed and Cochrane databases for articles pertaining to the "intracerebral hemorrhage score." Relevant articles were selected for analysis and discussion of potential modifications to account for increasing surgical indications.

RESULTS

A total of 64 articles were reviewed in depth and identified 37 clinical grading scales for prognostication of spontaneous intracerebral hemorrhage. The original ICH score remains the most widely used and validated. Various authors proposed modifications for improved prognostic accuracy, though no single scale showed consistent superiority. Most recently, scales to account for advances in surgical techniques have been developed but lack external validation.

CONCLUSION

We provide the most comprehensive review to date of prognostic grading scales for patients with intracerebral hemorrhage. Current prognostic tools for patients with intracerebral hemorrhage remain limited and may overestimate risk of a poor outcome. As minimally invasive surgical techniques are developed, prognostic scales should account for surgical candidacy and outcomes.

Vedolizumab Dose Escalation Improves Therapeutic Response in a Subset of Patients with Ulcerative Colitis

BACKGROUND

The Gemini trial failed to detect a significant difference in response rate for patients with ulcerative colitis (UC) randomized to standard (every 8 week) vedolizumab dosing vs escalated (every 4 week) dosing. Subsequent real-world data imply the Gemini trial design may have obscured a benefit of escalated dosing.

AIMS

We investigated outcomes after vedolizumab dose escalation for patients with UC. We also explored potential clinical predictors of dose escalation requirement.

METHODS

In this retrospective study, we included patients with UC who received vedolizumab between 1/2017-1/2019. We compared rates of clinical response (decrease in partial Mayo score by ≥ 2) and remission (partial Mayo < 2) for standard vs escalated dosing.

RESULTS

Among the 90 patients reviewed, 52 achieved and maintained remission on standard dosing. The average time to remission with standard dosing was 33.3 ± 6.6 weeks. After an average of 56.3 ± 7.4 weeks standard dosing, 24 patients (22 "partial responders" and 2 "non-responders") were dose-escalated. Of the 22 "partial responders" dose-escalated, 10 (45%) achieved remission, 10 (45%) achieved further improvement. Neither "non-responder" demonstrated further clinical benefit. Prior anti-tumor necrosis factor (anti-TNF) biologic exposure predicted dose escalation requirement (p = 0.008). Patients requiring dose escalation had more severe disease at baseline as measured by both full Mayo (p = 0.009) and partial Mayo scores (p = 0.01).

CONCLUSIONS

We show dose escalation benefited patients with UC who exhibit a "partial response" to standard dosing. Early vedolizumab dose escalation should be considered in both patients with severe disease and those with prior anti-TNF experience.

Small molecule approaches to treat autoimmune and inflammatory diseases (Part I): Kinase inhibitors

Autoimmune and inflammatory diseases place a huge burden on the healthcare system. Small molecule (SM) therapeutics provide much needed complementary treatment options for these diseases. This digest series highlights the latest progress in the discovery and development of safe and efficacious SMs to treat autoimmune and inflammatory diseases with each part representing a class of SMs, namely: 1) protein kinases; 2) nucleic acid-sensing pathways; and 3) soluble ligands and receptors on cell surfaces. In this first part of the series, the focus is on kinase inhibitors that emerged between 2018 and 2020, and which exhibit increased target and tissue selectivity with the aim of increasing their therapeutic index.

Design, synthesis, and evaluation of liver-specific gemcitabine prodrugs for potential treatment of hepatitis C virus infection and hepatocellular carcinoma

Many successful anti-viral and anti-cancer drugs are nucleoside analogs, which disrupt RNA and/or DNA synthesis. Here, we present liver-specific prodrugs of the chemotherapy drug gemcitabine (2',2'-difluorodeoxycytidine) for the treatment of hepatitis C virus (HCV) infection and hepatocellular carcinoma. The prodrugs were synthesized by introducing aromatic functional moieties to the cytosine 4-NH₂ group of gemcitabine via amide bonds. The chemical modification was designed to i) enable passive diffusion across cellular membrane, ii) protect the prodrugs from inactivating deamination by cellular enzymes, and iii) allow release of active gemcitabine after amide hydrolysis by high levels of carboxylesterases in the liver. We found that many of our prodrugs exhibited similar toxicity as gemcitabine toward liver- and kidney-derived cancer cell lines but were 24- to 620-fold less cytotoxic than gemcitabine in breast- and pancreas-derived cancer cells, respectively. The prodrugs also inhibited an HCV replicon with IC₅₀ values ranging from 10 nM-1.7 μM. Moreover, many of the prodrugs had therapeutic index values of >10,000 and have synergetic effects when combined with other Food and Drug Administration-approved anti-HCV small molecule drugs. These characteristics support the development of gemcitabine prodrugs as liver-specific therapeutics.

Gastrocolic ligament lymph-node dissection may increase the incidence of delayed gastric emptying after colon cancer surgery with D3 lymphadenectomy

PURPOSE

Delayed gastric emptying (DGE) is associated with prolonged hospital stay and higher healthcare costs. This study aimed to investigate the risk factors for DGE after D3 radical resection for colon cancer and to build a nomogram for this complication.

METHODS

We analyzed, retrospectively, 1160 consecutive patients who underwent surgery with D3 lymphadenectomy for colon cancer between January, 2012 and June, 2018. A multivariate logistic regression analysis was used to identify the risk factors for DGE and to build a DGE nomogram model.

RESULTS

There were ten, six and four patients with DGE classified as grades A, B and C, respectively, representing a DGE rate of 1.7%. Multivariate analysis revealed that age (P = 0.001), dissection of the gastrocolic ligament lymph nodes (GCLNs) (P = 0.001), surgical duration (P = 0.017) and preoperative hemoglobin level (P = 0.016) were independent risk factors, and were included to build a predictive model for DGE. The therapeutic index of GCLN dissection was approximately half that of D3 lymphadenectomy (2.9 vs. 5.6).

CONCLUSIONS

DGE is more likely to develop in patients aged > 75 years, those with a preoperative hemoglobin < 90 g/L, those with a surgical duration > 210 min, and those who undergo GCLN dissection. The nomogram may facilitate the stratification of patients at risk for DGE following D3 lymphadenectomy for colon cancer. Assessing long-term outcomes will help to evaluate the survival benefit of GCLN dissection in the future, to avoid unnecessary dissection and reduce the incidence of DGE.

Modulating pyrimidine ribonucleotide levels for the treatment of cancer

By providing the necessary building blocks for nucleic acids and precursors for cell membrane synthesis, pyrimidine ribonucleotides are essential for cell growth and proliferation. Therefore, depleting pyrimidine ribonucleotide pools has long been considered as a strategy to reduce cancer cell growth. Here, we review the pharmacological approaches that have been employed to modulate pyrimidine ribonucleotide synthesis and degradation routes and discuss their potential use in cancer therapy. New developments in the treatment of myeloid malignancies with inhibitors of pyrimidine ribonucleotide synthesis justify revisiting the literature as well as discussing whether targeting this metabolic pathway can be effective and sufficiently selective for cancer cells to warrant an acceptable therapeutic index in patients.

Therapeutic value of splenectomy to dissect splenic hilar lymph nodes for type 4 gastric cancer involving the greater curvature, compared with other types

BACKGROUND

Whether splenectomy for splenic hilar lymph node (No. 10) dissection in type 4 gastric cancer involving the greater curvature is necessary is not established. Patients with type 4 gastric cancer often experience peritoneal relapse, despite curative surgery, and total gastrectomy with splenectomy is frequently associated with infectious complications.

METHOD

Patients with cT2-T4 gastric cancer in the upper or middle third of the stomach, or both, involving the greater curvature who underwent R0 total gastrectomy with splenectomy between 2006 and 2016 were selected. Clinicopathological findings, postoperative complications, the incidence of lymph node metastasis, and the therapeutic value index of each station were compared between type 4 and non-type 4 gastric cancer.

RESULTS

We enrolled 50 patients with type 4 and 60 with non-type 4. The former had a significantly higher proportion of the undifferentiated type and larger and deeper tumors. The overall incidence of Grade III or higher complications was 20.9%. The incidence of No. 10 metastasis was 26.0% in type 4 and 31.7% in non-type 4. Although the therapeutic value index of the No. 10 was 13.7 in type 4 and 15.0 in non-type 4, the index of type 4 ranked just below several peri-gastric stations and seventh, while that in non-type 4 ranked second.

CONCLUSION

Splenectomy for No. 10 dissection may be oncologically valid for type 4 gastric cancer involving the greater curvature. A safer procedure for No. 10 dissection should be established.

Optimal extent of central lymphadenectomy for right-sided colon cancers: is lymphadenectomy beyond the superior mesenteric vein meaningful?

PURPOSE

The objective of the current study was to assess the therapeutic benefit of lymphadenectomy according to the extent of lymphadenectomy.

METHODS

Patients undergoing colectomy for right-sided colon cancer were identified. Distribution of lymph node metastases (DLNM) of 1, 2 and 3 were defined as lymph node metastasis (LNM) in the pericolic nodes, the intermediate nodes and the front of the SMV near the origin of the major artery, respectively. The therapeutic index (TI) was calculated based on the frequency of LNM and the 5 year overall survival (OS) rate of patients with LNM.

RESULTS

Among 344 patients who met the inclusion criteria, roughly half had LNM (n = 150, 43.7%). While 107 (31.1%) and 30 (8.7%) patients had DLNM1 and DLNM2, respectively, only 13 patients (3.8%) were defined as DLNM3. However, there was no significant difference in 5 year OS by DLNM (DLNM1 71.1%, DLNM2 78.7%, DLNM3 50.4%, p = 0.61). Overall, the TI of lymphadenectomy for D3 area was approximately 1/10 of the TI for D1 (1.9 vs.22.1), given the low frequency of LNM (3.8%) and poor 5 year OS of patients with LNM (50.4%). This trend was consistent irrespective of primary tumor locations.

CONCLUSION

The survival benefit from central lymphadenectomy namely D3 was low among patients with right-sided colon cancers.

Comparative therapeutic index, lethal time and safety margin of various toxicants and snake antivenoms using newly derived and old formulas

OBJECTIVE

The assessment of clinical efficacy and toxicity is very important in pharmacology and toxicology. The effects of psychostimulants (e.g. amphetamine), psychotomimetics (e.g. Cannabis sativus) and snake antivenoms are sometimes unpredictable even at lower doses, leading to serious intoxication and fatal consequences. Hence, there is need to re-assess some formulas for calculation of therapeutic index, lethal time and safety margin with a view to identifying therapeutic agents with remarkable toxicity potentials.

RESULTS

The therapeutic index formula [Formula: see text] was derived from T1 = LD50/ED50 and ED50 = [Formula: see text]. Findings have shown that, therapeutic index is a function of death reversal (s), safety factor (10-4) and weight of animal (Wa). However, the new safety margin formula [Formula: see text] derived from LT50 = [Formula: see text] and MS = [Formula: see text] shows that safety margin is a function of cube root of ratio between LT50 and LD50 and ED100th. Concentration (k) of toxicant at the receptor [Formula: see text] derived from D1 × Tn = K and LD1 = [Formula: see text] shows that therapeutic index, lethal time and safety margin is a function of drug or toxicant concentration at the receptor, the drug-receptor interaction and dose of toxicant or drug administered at a particular time.

Evofosfamide sensitizes esophageal carcinomas to radiation without increasing normal tissue toxicity

BACKGROUND AND PURPOSE

Esophageal cancer incidence is increasing and is rarely curable. Hypoxic tumor areas cause resistance to conventional therapies, making them susceptible for treatment with hypoxia-activated prodrugs (HAPs). We investigated in vivo whether the HAP evofosfamide (TH-302) could increase the therapeutic ratio by sensitizing esophageal carcinomas to radiotherapy without increasing normal tissue toxicity.

MATERIALS AND METHODS

To assess therapeutic efficacy, growth of xenografted esophageal squamous cell (OE21) or adeno (OE19) carcinomas was monitored after treatment with TH-302 (50 mg/kg, QD5) and irradiation (sham or 10 Gy). Short- and long-term toxicity was assessed in a gut mucosa and lung fibrosis irradiation model, sensitive to acute and late radiation injury respectively. Mice were injected with TH-302 (50 mg/kg, QD5) and the abdominal area (sham, 8 or 10 Gy) or the upper part of the right lung (sham, 20 Gy) was irradiated. Damage to normal tissues was assessed 84 hours later by histology and blood plasma citrulline levels (gut) and for up to 1 year by non-invasive micro CT imaging (lung).

RESULTS

The combination treatment of TH-302 with radiotherapy resulted in significant tumor growth delay in OE19 (P = 0.02) and OE21 (P = 0.03) carcinomas, compared to radiotherapy only. Irradiation resulted in a dose-dependent decrease of crypt survival (P < 0.001), mucosal surface area (P < 0.01) and citrulline levels (P < 0.001) in both tumor and non-tumor bearing animals. On the long-term, irradiation increased CT density in the lung, indicating fibrosis, over time. TH-302 did not influence the radiation-induced short-term and long-term toxicity, confirmed by histological evaluation.

CONCLUSION

The combination of TH-302 and radiotherapy might be a promising approach to improve the therapeutic index for esophageal cancer patients.

Pharmacokinetics and pharmacodynamics of inhaled corticosteroids for asthma treatment

The differences in the pharmacokinetic (PK) characteristics of inhaled corticosteroids (ICSs) critically influence the profile of each of them, but also the significant differences in glucocorticoid receptor selectivity, potency, and physicochemical properties are critical in defining the pharmacodynamic (PD) profile of an ICS. The PK and PD properties of ICSs used in asthma and the importance of their interrelationship have been reviewed. The differences among the ICSs in PK and PD must be considered when an ICS should be prescribed to an asthmatic patient because a better understanding of the PK/PD interrelationship of ICSs could be important to better fit with the between-patient variability and within-patient repeatability in the response to ICSs that often complicate the therapeutic approach to the asthmatic patient. The role of the device in influencing the PK profile of an ICS must be always considered because it is crucial. Also patient-related factors and disease severity affect pulmonary deposition of ICS.

Toxicity of formalin for fingerlings of Cyprinus carpio var. koi and in vitro efficacy against Dactylogyrus minutus Kulwièc, 1927 (Monogenea: Dactylogyridae)

The toxicity of formalin on Cyprinus carpio var. koi and its anti-parasite effects against Dactylogyrus minutus (Monogenea) in in vitro tests is analyzed. Specimens of D. minutus were submitted to eight concentrations of formalin: 50, 75, 100, 125, 150, 175, 200, 250 mg L^-1, in triplicate. Concentrations of formalin 100, 150 and 200 mg L^-1 were then tested to determine the median lethal concentration of 50% of the fish per immersion bath. Fish behavior was also observed during the first 6 h of exposure. The 200 mg L^-1 concentration was the most rapid efficacy for D. minutus, killing all parasites in 16 min. All parasites were killed in 47 min at concentration 100 mg L^-1. Concentration 200 mg L^-1 was the most lethal for fish in less than 24 h exposure, with 24 h LC₅₀ at 135.44 (119.78-153.14) mg L^-1. The therapeutic index was 2.05-30 min and 1.15-16 min. A short bath (1 h) is recommended in koi carp with a minimum concentration of 75 mg L^-1 of formalin, not exceeding 100 mg L^-1 for treatment against D. minutus.

Towards lead compounds as anti-cancer agents via new phaeosphaeride A derivatives

New derivatives of phaeosphaeride A (PPA) were synthesized and characterized. Anti-tumor studies were carried out on the U937, HCT-116, PC3, MCF-7, A549, К562, NCI-H929, Jurkat, THP-1, RPMI8228 tumor cell lines, and on the HEF cell line. All the compounds synthesized were found to have better efficacy than PPA towards the tumor cell lines mentioned. Compound 6 (IC₅₀ = 0.59 ± 0.27 µM) was observed to be 11 times more active than PPA (IC₅₀ = 6.5 ± 0.30 µM) towards the NCI-H929 cell line, with a therapeutic index of 18. Compound 6 was determined to be over half and 16 times more active than etoposide towards the NCI-H929 (IC₅₀ = 0.9 ± 0.05 µM) and A549 (IC₅₀ = 100 ± 7.0 µM) cell lines, respectively.

Cell-selectivity of tryptophan and tyrosine in amphiphilic α-helical antimicrobial peptides against drug-resistant bacteria

The increasing emergence of drug-resistant bacteria creates a requirement for new antibiotics and various types of antibiotic materials such as proteins, peptides, polymers, and chemical compounds. Among these, antimicrobial peptides (AMPs) are considered to be promising antibiotic candidates for clinical treatments. In this study, we have designed a novel series of peptides with repeated sequences of minimum membrane-active motif, 'XWZX' basic sequence (X: lysine or arginine, Z: leucine, tyrosine, valine, or glycine), and an α-helical secondary structure. Some peptides displayed a potent antibacterial activity via membranolytic action and high therapeutic index (toxic dose/minimum inhibitory concentration) in vitro. Furthermore, in vivo experiments using bacterial ear-skin infection models verified that these peptides have the potential to be powerful and safe antibiotics. The present study provides a lead sequence for designing peptide antibiotics against bacterial membranes and information for cell-selectivity of hydrophobic amino acids with aromatic side chains such as Trp and Tyr.

Characterization and phase I study of CLR457, an orally bioavailable pan-class I PI3-kinase inhibitor

Background CLR457 is an orally bioavailable pan-phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) inhibitor. Methods CLR457 anti-tumor activity and pharmacokinetics (PK) were characterized by in vitro biochemical assays and in vivo tumor xenografts. A first-in-human study was conducted to determine the maximum tolerated dose (MTD), safety, PK, and efficacy of CLR457. Successive cohorts of patients with advanced solid tumors with PI3K pathway activation received increasing CLR457 doses according to a Bayesian escalation model based on the rate of dose limiting toxicity (DLT) in the first 28-day cycle. Results CLR457 inhibited p110α, p110β, p110δ and p110γ isoforms with an IC₅₀ of 89 ± 29 nM, 56 ± 35 nM, 39 ± 10 nM and 230 ± 31 nM, respectively. CLR457 exhibited dose-dependent antitumor activity and interfered with glucose homeostasis in PI3K-mutant tumor xenografts. 31 patients received doses ranging from 5 to 100 mg. DLTs included grade 3 hyperglycemia and rash (3). In the 100 mg cohort (n = 11), 3 (27.3%) patients had DLTs and all patients (100%) experienced ≥ grade 3 toxicity with rash (45.5%) as the most common event. The MTD was not determined. For the entire study population, stomatitis (45.2%), diarrhea (38.7%), rash (35.5%) were the most common any grade toxicities—51.6% patients experienced ≥ Grade 3 toxicity. CLR457 was rapidly absorbed with limited accumulation and linear PK. PK modeling indicated that pharmacologically active concentrations were achieved at the highest dose tested (100 mg), though no objective responses were observed. Conclusion CLR457 clinical development was terminated due to poor tolerability and limited antitumor activity. These results emphasize the difficulty of achieving a wide therapeutic index when targeting all class I PI3K-isoforms.

Non-toxic and non teratogenic extract of Thuja orientalis L. inhibited angiogenesis in zebra fish and suppressed the growth of human lung cancer cell line

Lung cancer is a malignant tumour with minimal survival rate and the current treatments are not showing complete remission of tumour and have many side effects. Thus a natural herbal medicine with good anti-cancer properties is highly demanded. Thuja orientalis L. is a traditionally used medicine to cure cough, bronchitis, excessive menstruation, asthma, skin infection and premature baldness. In addition, recent studies have revealed that it has anti-proliferative and anti-cancer activity. Angiogenesis is the main reason for the propagation and metastasis of cancers. We therefore intended to study the effects of the leaf extract of Thuja orientalis L. on angiogenesis as well as lung cancer cell growth. We have tested the anti-angiogenesis efficiency by alkaline phosphatase assay and also analysed the in vivo toxicity and teratogenic effects of various concentration of Thuja orientalis L. extract by establishing an in vivo zebra fish (Danio rerio), a promising model for cancer research which share genetic structure similarity to that of human beings. Also we demonstrated an anti-cancer effect of leaf extract from Thuja orientalis L. on human lung cancer cell line (A549) by MTT and trypan blue assay. The results revealed that the Thuja orientalis L. extract is efficient in repressing lung tumour cell growth significantly (p ≤ 0.01) in all treatments (2.4 mg/ml to 0.3 mg/ml) except 0.15 mg/ml compared to the control. The in vivo toxicity assay has proven that it is non-toxic at concentrations 0.6 mg/ml, 0.3 mg/ml and 0.15 mg/ml in zebrafish. The teratogenic assays revealed the therapeutic index (TI) as 0.808 with 0.7029 mg/ml as LC₅₀ concentration at 24 h which is within the desirable value (below 1) for drug administration. Noticeable inhibition of angiogenesis also was observed in treatment with 2.4 mg/ml to 0.3 mg/ml. Overall we found that Thuja orientalis L. plant leaf extract exhibits better anti-cancer properties as we have validated by in vitro and in vivo analysis.

Priority of lymph node dissection for proximal gastric cancer invading the greater curvature

BACKGROUND

The therapeutic efficacy of dissection of the splenic hilar lymph nodes (#10) has not been fully evaluated in locally advanced proximal gastric cancer (LAGC) invading the greater curvature of the stomach.

METHODS

Patients with LAGC invading the greater curvature who underwent D2 total gastrectomy with splenectomy between January 2000 and May 2015 were retrospectively examined. The therapeutic value index was calculated by multiplying the metastatic rate of a station and the 5-year survival of patients with metastasis to that station; the metastatic rate and the index of each lymph node station were then compared.

RESULTS

In total, 82 patients were eligible for the present study. The most frequent metastatic node was #3, followed by #1, #4d and #7, #2, #4sa and #10, and #4sb and #9. These lymph nodes had a metastatic rate of more than 10%. The node station with the highest index was #3, followed by #7, #4d, #1, #4sb, #4sa, #2, and #9. The index of #10 was lower, but exceeded those of #8a and #11p.

CONCLUSIONS

The metastatic rate of #10 was relatively high at 13%, and the therapeutic value index was as high as those of other suprapancreatic nodes. D2 dissection for proximal cancer located in the greater curvature should include removal of node #10.

Techniques for Monitoring Drug Efficacy

The efficacy of drugs can vary greatly between species and individuals. Establishing efficacious drug doses for a species requires integration of population pharmacokinetic and pharmacodynamic data into a dose-response curve. Unfortunately, these data sets are rarely available for exotic species. The use of alternative monitoring techniques is required to determine drug efficacy and safety. This article discusses methods to integrate efficacy monitoring into clinical practice, including the use of diagnostic testing and therapeutic drug monitoring.

A novel bispecific antibody fusion protein co-targeting EGFR and CD47 with enhanced therapeutic index

OBJECTIVE

To promote targeting specificity of anti-CD47 agents, we have constructed a novel bispecific antibody fusion protein against EGFR and CD47, which may minimize the "off-target" effects caused by CD47 expression on red blood cells.

RESULTS

The novel bispecific antibody fusion protein, denoted as Bi-SP could simultaneously bind to EGFR and CD47 and exhibited potent phagocytosis-stimulation effects in vitro. Bi-SP treatment with a low dose more effectively inhibited tumor growth than either EGFR-targeting antibody, Pan or the SIRPα variant-Fc (SIRPαV-Fc) in the A431 xenograft tumor model. In addition, the treatment with Bi-SP produced less red blood cell (RBC) losses than the SIRPαV-Fc treatment, suggesting its potential use for minimizing RBC toxicity in therapy.

CONCLUSIONS

Bi-SP with improved therapeutic index has the potential to treat CD47+ and EGFR+ cancers in clinics.

Picolyl amides of betulinic acid as antitumor agents causing tumor cell apoptosis

A series of picolyl amides of betulinic acid (3a-3c and 6a-6c) was prepared and subjected to the cytotoxicity screening tests. Structure-activity relationships studies resulted in finding differences in biological activity in dependence on o-, m- and p-substitution of the pyridine ring in the target amides, when cytotoxicity data of 3a-3c and 6a-6c were obtained and compared. The amides 3b and 3a displayed cytotoxicity (given in the IC₅₀ values) in G-361 (0.5 ± 0.1 μM and 2.4 ± 0.0 μM, respectively), MCF7 (1.4 ± 0.1 μM and 2.2 ± 0.2 μM, respectively), HeLa (2.4 ± 0.4 μM and 2.3 ± 0.5 μM, respectively) and CEM (6.5 ± 1.5 μM and 6.9 ± 0.4 μM, respectively) tumor cell lines, and showed weak effect in the normal human fibroblasts (BJ). Selectivity against all tested cancer cells was determined and compared to normal cells with therapeutic index (TI) between 7 and 100 for compounds 3a and 3b. The therapeutic index (TI = 100) was calculated for human malignant melanoma cell line (G-361) versus normal human fibroblasts (BJ). The cytotoxicity of other target amides (3c and 6a-6c) revealed lower effects than 3a and 3b in the tested cancer cell lines.

Continuous low plasma concentrations of everolimus provides equivalent efficacy to oral daily dosing in mouse xenograft models of human cancer

PURPOSE

Everolimus is a drug used successfully in a number of different oncology indications, but significant on-target toxicities exist. We explored the possibility of improving the therapeutic index (TI) by studying alternative means of administering the drug based upon low continuous dosing.

METHODS

All studies were performed using naïve nude mice or nude mice bearing s.c. human renal 786-O tumours or human breast MDA-MB-468 tumours. Everolimus was administered via a standard emulsion, either i.v., p.o., i.p., s.c., or via s.c. osmotic mini-pumps (MP) or via poly-lactic-co-glycolic (PLGA)-microparticles (PLGA-µP) prepared from everolimus powder injected s.c. Total-drug levels in blood, plasma or tissues were quantified ex vivo by LC-MS/MS. Efficacy studies were performed over 2-3 weeks and toxicity assessed by changes in body weight, glucose and white blood cell count. Effects on tumour activity biomarkers were quantified using reverse-phase protein array.

RESULTS

Everolimus administration s.c. in an emulsion decreased the absorption rate but increased the C _max and bio-availability of everolimus compared to standard approaches of administration p.o. or i.p. Everolimus administration s.c. via MP or PLGA-µP reduced the C _max and provided continuous low concentrations of everolimus in the plasma, which inhibited tumour pS6/S6 to a similar degree to oral administration. Toxicities such as changes in body weight or white blood cell count were unaffected. Provided the everolimus concentration was above the free unbound IC50 for proliferation of the tumour cell line, efficacy could be achieved equivalent to that provided by standard oral administration. However, an overall improvement in the TI could not be demonstrated.

CONCLUSIONS

Continuous low plasma concentrations of everolimus can provide strong efficacy in preclinical models, which if translatable to the clinic may reduce on-target toxicities and so increase the TI.

Modulating short tryptophan- and arginine-rich peptides activity by substitution with histidine

BACKGROUND

High antimicrobial efficacy of short tryptophan-and arginine-rich peptides makes them good candidates in the fight against pathogens. Substitution of tryptophan and arginine by histidine could be used to modulate the peptides efficacy by optimizing their structures.

METHODS

The peptide (RRWWRWWRR), reported to showed good antimicrobial efficacy, was used as template, seven new analogs being designed substituting tryptophan or arginine with histidine. The peptides' efficacy was tested against E. coli, B. subtilis and S. aureus. The cytotoxicity and hemolytic effect were evaluated and the therapeutic index was inferred for each peptide. Atomic force microscopy and molecular simulation were used to analyze the effects of peptides on bacterial membrane.

RESULTS

The substitution of tryptophan by histidine proved to strongly modulate the antimicrobial activity, mainly by changing the peptide-to-membrane binding energy. The substitution of arginine has low effect on the antimicrobial efficacy. The presence of histidine residue reduced the cytotoxic and hemolytic activity of the peptides in some cases maintaining the same efficacy against bacteria. The peptides' antimicrobial activity was correlated to the 3D-hydrophobic moment and to a simple structure-based packing parameter.

CONCLUSION

The results show that some of these peptides have the potential to become good candidates to fight against bacteria. The substitution by histidine proved to fine tune the therapeutic index allowing the optimization of the peptide structure mainly by changing its binding energy and 3D-hydrophobic moment.

GENERAL SIGNIFICANCE

The short tryptophan reach peptides therapeutic index can be maximized using the histidine substitution to optimize their structure.

High-throughput screening for the identification of small-molecule inhibitors of the flaviviral protease

The mosquito-borne dengue virus serotypes 1-4 (DENV1-4) and West Nile virus (WNV) cause serious illnesses worldwide associated with considerable morbidity and mortality. According to the World Health Organization (WHO) estimates, there are about 390 million infections every year leading to ∼500,000 dengue haemorrhagic fever (DHF) cases and ∼25,000 deaths, mostly among children. Antiviral therapies could reduce the morbidity and mortality associated with flaviviral infections, but currently there are no drugs available for treatment. In this study, a high-throughput screening assay for the Dengue protease was employed to screen ∼120,000 small molecule compounds for identification of inhibitors. Eight of these inhibitors have been extensively analyzed for inhibition of the viral protease in vitro and cell-based viral replication using Renilla luciferase reporter replicon, infectivity (plaque) and cytotoxicity assays. Three of these compounds were identified as potent inhibitors of DENV and WNV proteases, and viral replication of DENV2 replicon and infectious RNA. Fluorescence quenching, kinetic analysis and molecular modeling of these inhibitors into the structure of NS2B-NS3 protease suggest a mode of inhibition for three compounds that they bind to the substrate binding pocket.

In vitro evaluation of antifungal and cytotoxic activities as also the therapeutic safety of the oxidized form of amphotericin B

The aim of this study was to evaluate the antifungal and cytotoxic activities of the oxidized form of amphotericin B (AmB-Ox) as well as to determine whether oxidation process of AmB is therapeutically beneficial in vitro. The antifungal activity was estimated against Candida albicans ATCC 10231 and Candida parasilosis ATCC 22019 by broth microdilution method according to the NCCLS M27-A2 standards. The in vitro cytotoxicity was evaluated using normal green monkey kidney cells (GMK) by MTT assay. The obtained results demonstrated that AmB-Ox possesses 16-fold decreased antifungal properties against the two Candida strains and 5-fold lower cytotoxic activity towards GMK cells in comparison with AmB. The therapeutic safety in vitro assessed by calculating the ratio between cytotoxicity (CC50 value) to antifungal activity (MIC value) showed that oxidation of AmB is a very unfavourable process in vitro, because leads to formation of derivative (AmB-Ox) that lost antifungal properties much more rapidly than cytotoxic activity. Thus, the process of the oxidation of AmB in vivo (if it occurs) can be also highly harmful for patient.

Peptides from the scorpion Vaejovis punctatus with broad antimicrobial activity

The antimicrobial potential of two new non-disulfide bound peptides, named VpAmp1.0 (LPFFLLSLIPSAISAIKKI, amidated) and VpAmp2.0 (FWGFLGKLAMKAVPSLIGGNKSSSK) is here reported. These are 19- and 25-aminoacid-long peptides with +2 and +4 net charges, respectively. Their sequences correspond to the predicted mature regions from longer precursors, putatively encoded by cDNAs derived from the venom glands of the Mexican scorpion Vaejovis punctatus. Both peptides were chemically synthesized and assayed against a variety of microorganisms, including pathogenic strains from clinical isolates and strains resistant to conventional antibiotics. Two shorter variants, named VpAmp1.1 (FFLLSLIPSAISAIKKI, amidated) and VpAmp2.1 (FWGFLGKLAMKAVPSLIGGNKK), were also synthesized and tested. The antimicrobial assays revealed that the four synthetic peptides effectively inhibit the growth of both Gram-positive (Staphylococcus aureus and Streptococcus agalactiaea) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria, with MICs in the range of 2.5-24.0 μM; yeasts (Candida albicans and Candida glabrata) with MICs of 3.1-50.0 μM; and two clinically isolated strains of Mycobacterium tuberculosis-including a multi-drug resistant one- with MICs in the range of 4.8-30.5 μM. A comparison between the activities of the original peptides and their derivatives gives insight into the structural/functional role of their distinctive residues.

Therapeutic index modeling and predictive QSAR of novel thiazolidin-4-one analogs against Toxoplasma gondii

The main idea of this study was to find predictive quantitative structure-activity relationships (QSAR) for the therapeutic index of 68 thiazolidin-4-one analogs against Toxoplasma gondii. Multivariate adaptive regression spline (MARS) together with Monte-Carlo (MC) sampling was proposed as a reliable descriptor subset selection strategy. Basis functions and knot points are also determined for each selected descriptor using generalized cross validation after frequency analysis. Least squares-support vector regression (LS-SVR) with optimized hyper-parameters was employed as mapping tool due to its promising empirical performance. The models were validated and tested through the use of the external prediction set of compounds, leave-one-out and leave-many-out cross validation methods, applicability domain analysis and Y-randomization. The robustness and accuracy of the QSAR models were confirmed by the satisfactory statistical parameters for the experimentally reported dataset (R(2)p=0.853, Q(2)LOO=0.785, R(2)L20%O=0.742 and r(2)m=0.715) and low standard error values (RMSEp=0.208, RMSELOO=0.321 and RMSEL20%O=0.376). The comprehensive analysis carried out in the present contribution using the proposed strategy can provide a considerable basis for the design and development of novel drug-like molecules against T.gondii.

Bio-active engineered 50 nm silica nanoparticles with bone anabolic activity: therapeutic index, effective concentration, and cytotoxicity profile in vitro

Silica-based nanomaterials are generally considered to be excellent candidates for therapeutic applications particularly related to skeletal metabolism however the current data surrounding the safety of silica based nanomaterials is conflicting. This may be due to differences in size, shape, incorporation of composite materials, surface properties, as well as the presence of contaminants following synthesis. In this study we performed extensive in vitro safety profiling of ∼ 50 nm spherical silica nanoparticles with OH-terminated or Polyethylene Glycol decorated surface, with and without a magnetic core, and synthesized by the Stöber method. Nineteen different cell lines representing all major organ types were used to investigate an in vitro lethal concentration (LC) and results revealed little toxicity in any cell type analyzed. To calculate an in vitro therapeutic index we quantified the effective concentration at 50% response (EC50) for nanoparticle-stimulated mineral deposition activity using primary bone marrow stromal cells (BMSCs). The EC50 for BMSCs was not substantially altered by surface or magnetic core. The calculated Inhibitory concentration 50% (IC50) for pre-osteoclasts was similar to the osteoblastic cells. These results demonstrate the pharmacological potential of certain silica-based nanomaterial formulations for use in treating bone diseases based on a favorable in vitro therapeutic index.

Antiplasmodial, cytotoxic activities and characterization of a new naturally occurring quinone methide pentacyclic triterpenoid derivative isolated from Salacia leptoclada Tul. (Celastraceae) originated from Madagascar

OBJECTIVE

To validate scientifically the traditional use of Salacia leptoclada Tul. (Celastraceae) (S. leptoclada) and to isolate and elucidate the structure of the biologically active compound.

METHODS

Bioassay-guided fractionation of the acetonic extract of the stem barks of S. leptoclada was carried out by a combination of chromatography technique and biological experiments in viro using Plasmodium falciparum and P388 leukemia cell lines as models. The structure of the biologically active pure compound was elucidated by 1D and 2D NMR spectroscopy and mass spectrometry.

RESULTS

Biological screening of S. leptoclada extracts resulted in the isolation of a pentacyclic triterpenic quinone methide. The pure compound exhibited both in vitro a cytotoxic effect on murine P388 leukemia cells with IC50 value of (0.041±0.020) μg/mL and an antiplasmodial activity against the chloroquine-resistant strain FC29 of Plasmodium falciparum with an IC50 value of (0.052±0.030) μg/mL. Despite this interesting anti-malarial property of the lead compound, the therapeutic index was weak (0.788). In the best of our knowledge, the quinone methide pentacyclic triterpenoid derivative compound is reported for the first time in S. leptoclada.

CONCLUSIONS

The results suggest that furthers studies involving antineoplastic activity is needed for the development of this lead compound as anticancer drug.