Phase I Clinical Pharmacology Study of F14512, a New Polyamine-Vectorized Anticancer Drug, in Naturally Occurring Canine Lymphoma

Podophyllotoxin: Recent Advances in the Development of Hybridization Strategies to Enhance Its Antitumoral Profile

Podophyllotoxin is a naturally occurring cyclolignan isolated from rhizomes of Podophyllum sp. In the clinic, it is used mainly as an antiviral; however, its antitumor activity is even more interesting. While podophyllotoxin possesses severe side effects that limit its development as an anticancer agent, nevertheless, it has become a good lead compound for the synthesis of derivatives with fewer side effects and better selectivity. Several examples, such as etoposide, highlight the potential of this natural product for chemomodulation in the search for new antitumor agents. This review focuses on the recent chemical modifications (2017-mid-2023) of the podophyllotoxin skeleton performed mainly at the C-ring (but also at the lactone D-ring and at the trimethoxyphenyl E-ring) together with their biological properties. Special emphasis is placed on hybrids or conjugates with other natural products (either primary or secondary metabolites) and other molecules (heterocycles, benzoheterocycles, synthetic drugs, and other moieties) that contribute to improved podophyllotoxin bioactivity. In fact, hybridization has been a good strategy to design podophyllotoxin derivatives with enhanced bioactivity. The way in which the two components are joined (directly or through spacers) was also considered for the organization of this review. This comprehensive perspective is presented with the aim of guiding the medicinal chemistry community in the design of new podophyllotoxin-based drugs with improved anticancer properties.

Studying the DNA damage response pathway in hematopoietic canine cancer cell lines, a necessary step for finding targets to generate new therapies to treat cancer in dogs

Background

Dogs present a significant opportunity for studies in comparative oncology. However, the study of cancer biology phenomena in canine cells is currently limited by restricted availability of validated antibody reagents and techniques. Here, we provide an initial characterization of the expression and activity of key components of the DNA Damage Response (DDR) in a panel of hematopoietic canine cancer cell lines, with the use of commercially available antibody reagents.

Materials and methods

The techniques used for this validation analysis were western blot, qPCR, and DNA combing assay.

Results

Substantial variations in both the basal expression (ATR, Claspin, Chk1, and Rad51) and agonist-induced activation (p-Chk1) of DDR components were observed in canine cancer cell lines. The expression was stronger in the CLBL-1 (B-cell lymphoma) and CLB70 (B-cell chronic lymphocytic leukemia) cell lines than in the GL-1 (B-cell leukemia) cell line, but the biological significance of these differences requires further investigation. We also validated methodologies for quantifying DNA replication dynamics in hematopoietic canine cancer cell lines, and found that the GL-1 cell line presented a higher replication fork speed than the CLBL-1 cell line, but that both showed a tendency to replication fork asymmetry.

Conclusion

These findings will inform future studies on cancer biology, which will facilitate progress in developing novel anticancer therapies for canine patients. They can also provide new knowledge in human oncology.

Polyamine-Drug Conjugates: Do They Boost Drug Activity?

Over the past two decades, the strategy of conjugating polyamine tails with bioactive molecules such as anticancer and antimicrobial agents, as well as antioxidant and neuroprotective scaffolds, has been widely exploited to enhance their pharmacological profile. Polyamine transport is elevated in many pathological conditions, suggesting that the polyamine portion could improve cellular and subcellular uptake of the conjugate via the polyamine transporter system. In this review, we have presented a glimpse on the polyamine conjugate scenario, classified by therapeutic area, of the last decade with the aim of highlighting achievements and fostering future developments.

Prognostic value of pretreatment plasma D-dimer level in dogs with intermediate to high-grade non-Hodgkin lymphoma

Pretreatment D-dimer levels have been reported to predict survival in several types of malignancies in human patients. The objective of this study was to evaluate the prognostic value of pretreatment D-dimer level in dogs with intermediate to high-grade non-Hodgkin lymphoma (NHL). In a prospective, randomized, double-blind study of F14512 vs etoposide phosphate, we assessed the prognostic value of pretreatment plasma D-dimer level in 48 client-owned dogs diagnosed with intermediate to high-grade NHL. The correlation between pretreatment plasma D-dimer level and various clinical features, progression-free survival (PFS) and overall survival (OS) was analysed. The median value of pretreatment plasma D-dimer level was 0.4 μg/mL (range: 0.1-14.3 μg/mL). High pretreatment plasma D-dimer level (>0.5 μg/mL) was detected in 44% (21/48) of dogs. High D-dimer levels were not correlated with naive vs relapsed lymphoma, clinical stage, substage, immunophenotype or treatment group. D-dimer levels >0.5 μg/mL were significantly associated with inferior median PFS (54 vs 104 days, P = .011) and OS (93 vs 169 days, P = .003). In the multivariate analysis, high D-dimer levels remained an independent predictor for worse PFS (HR: 3.21, 95% CI: 1.57-6.56, P = .001) and OS (HR: 3.87, 95% CI: 1.88-7.98; P < .001). This study suggests that pretreatment plasma D-dimer level can serve as a predictor of prognosis in dogs with intermediate to high-grade NHL. Further studies are warranted to confirm these findings.

Design, synthesis, bioevaluation of LFC- and PA-tethered anthraquinone analogues of mitoxantrone

The clinical application of mitoxantrone (MTZ), a DNA-intercalating topoisomerase II (topo II) poison, has been largely limited by the risk of secondary tumor and severe myelosuppression. To develop more effective antineoplastic agents with less toxicity, a spectrum of anthraquinone analogues of MTZ were herein designed and synthesized based on the concept of 'enhancing protein backbone-binding', by rationally introducing hydrophobic long fatty acid chain (LFC) and hydrophilic polyamine (PA) components, which are reported to function as effective tumor-targeting tethers. The SAR exploration implicated that in our synthesized molecules, the introduction of both lipophilic LFC and hydrophilic PA fragment is plausibly beneficial to the anti-proliferative potency, with a certain degree of selectivity between the hematopoietic and solid malignant cells, which still need to be further accurately confirmed. Meanwhile, many compounds, the LFC-tethered 5d₂ and PA-bridged 8c in particular, provided satisfactory topo IIα inhibition by acting as DNA non-intercalators, largely attributable to their strong adaptability to three binding regions (pocket I, II and III) and also the generated H-bonding interactions between inhibitors and key residues of topo IIα. In brief, 5d₂ and 8c might be promising hits for further exploitation of more potent topo IIα inhibitors.

The Role of p53-Mediated Signaling in the Therapeutic Response of Colorectal Cancer to 9F, a Spermine-Modified Naphthalene Diimide Derivative

Colorectal cancer (CRC) is one of the most prevalent cancers due to its frequency and high rate of mortality. Polyamine-vectorized anticancer drugs possess multiple biological properties. Of these drugs, 9F has been shown to inhibit tumor growth and the metastasis of hepatocellular carcinoma. This current study aims to investigate the effects of 9F on CRC and determine its molecular mechanisms of action. Our findings demonstrate that 9F inhibits CRC cell growth by inducing apoptosis and cell cycle arrest, and suppresses migration, invasion and angiogenesis in vitro, resulting in the inhibition of tumor growth and metastasis in vivo. Based on RNA-seq data, further bioinformatic analyses suggest that 9F exerts its anticancer activities through p53 signaling, which is responsible for the altered expression of key regulators of the cell cycle, apoptosis, the epithelial-to-mesenchymal transition (EMT), and angiogenesis. In addition, 9F is more effective than amonafide against CRC. These results show that 9F can be considered as a potential strategy for CRC treatment.

Randomized, double-blind trial of F14512, a polyamine-vectorized anticancer drug, compared with etoposide phosphate, in dogs with naturally occurring lymphoma

Purpose: F14512 is an epipodophyllotoxin derivative from etoposide, combined with a spermine moiety introduced as a cell delivery vector. The objective of this study was to compare the safety and antitumor activity of F14512 and etoposide phosphate in dogs with spontaneous non-Hodgkin lymphoma (NHL) and to investigate the potential benefit of F14512 in P-glycoprotein (Pgp) overexpressing lymphomas.

Experimental Design: Forty-eight client-owned dogs with intermediate to high-grade NHL were enrolled into a randomized, double-blind trial of F14512 versus etoposide phosphate. Endpoints included safety and therapeutic efficacy.

Results: Twenty-five dogs were randomized to receive F14512 and 23 dogs to receive etoposide phosphate. All adverse events (AEs) were reversible, and no treatment-related death was reported. Hematologic AEs were more severe with F14512 and gastrointestinal AEs were more frequent with etoposide phosphate. F14512 exhibited similar response rate and progression-free survival (PFS) as etoposide phosphate in the global treated population. Subgroup analysis of dogs with Pgp-overexpressing NHL showed a significant improvement in PFS in dogs treated with F14512 compared with etoposide phosphate.

Conclusion: F14512 showed strong therapeutic efficacy against spontaneous NHL and exhibited a clinical benefice in Pgp-overexpressing lymphoma superior to etoposide phosphate. The results clearly justify the evaluation of F14512 in human clinical trials.

Evaluation of serum thymidine kinase 1 activity as a biomarker for treatment effectiveness and prediction of relapse in dogs with non-Hodgkin lymphoma

BACKGROUND

Serum thymidine kinase 1 (sTK1) activity is closely correlated with DNA synthesis.

OBJECTIVES

Evaluate sTK1 activity as a biomarker for treatment response and early detection of relapse in dogs with lymphoma.

ANIMALS

Ninety-seven client-owned dogs with naive or relapsed lymphoma and 23 healthy dogs.

METHODS

Prospective study. Serum TK1 activity measured by refined ELISA-based method (DiviTum assay, Biovica International) before treatment, at clinical response, and every 4 weeks until relapse or last follow-up.

RESULTS

Serum TK1 activity was ≤20 Du/L in 96% (22/23) of healthy dogs. Pretreatment sTK1 activity was >20 Du/L in 88% (85/97) dogs with lymphoma. At clinical response, sTK1 activity was significantly lower in dogs with complete (CR, n = 36) versus partial (PR, n = 29) response (P < .0001). Sensitivity (Se) and specificity (Sp) of sTK1 activity for detecting nonfully responders were 76% and 100%, respectively, with cutoff of 119.5 Du/L (AUC, 0.90; 95%-CI, 0.81-0.98; P < .0001). In dogs with CR, a 5-fold increase in sTK1 activity at a 4-week interval predicted relapse at the subsequent 4-week assessment with a Se 50% and Sp 94% (AUC, 0.72; 95%-CI, 0.55-0.90; P = .02). An increase of sTK1 activity (>2.7-fold value measured at clinical response) predicted relapse at subsequent 4-week assessment with a Se 61% and Sp 88% (AUC, 0.79; 95%-CI, 0.64-0.95; P = .004).

CONCLUSIONS AND CLINICAL IMPORTANCE

Monitoring sTK1 activity could help to detect complete responders and early disease progression in dogs with lymphoma.

Spermine modified polymeric micelles with pH-sensitive drug release for targeted and enhanced antitumor therapy

Tumor targeting delivery of chemotherapeutic drugs by nanocarriers has been demonstrated to be a promising strategy for cancer therapy with improved therapeutic efficacy. In this work, we reported a novel type of active targeting micelle with pH-responsive drug release by using biodegradable poly(lactide)-poly(2-ethyl-2-oxazoline) di-block copolymers functionalized with spermine (SPM). SPM has been considered as a tumor binding ligand through its specific interaction with the polyamine transport system (PTS), a transmembrane protein overexpressed on various types of cancer cell, while its application in nano-drug delivery systems has rarely been explored. The micelles with spherical shape (∼110 nm) could load hydrophobic paclitaxel (PTX) with high capacity, and release the payload much faster at acidic pH (4.5–6.5) than at pH 7.4. This pH-responsive property assisted the rapid escape of drug from the endo/lysosome after internalization as demonstrated by confocal laser scanning microscopy images using coumarin-6 (Cou-6) as a fluorescent probe. With surface SPM modification, the micelles displayed much higher cellular uptake than SPM lacking micelles in various types of cancer cells, demonstrating tumor targeting ability. The uptake mechanism of SPM modified micelles was explored by flow cytometry, which suggested an energy-consuming sag vesicle-mediated endocytosis pathway. As expected, the micelles displayed significantly enhanced anti-cancer activity. This work demonstrates that SPM modified pH-sensitive micelles may be potential drug delivery vehicles for targeting and effective cancer therapy.

Tumor targeting delivery of SPM functionalized micelles via PTS binding and their endocytosis and pH-triggered endo/lysosome drug release for anti-cancer therapy.

Polyamine-containing etoposide derivatives as poisons of human type II topoisomerases: Differential effects on topoisomerase IIα and IIβ

Etoposide is an anticancer drug that acts by inducing topoisomerase II-mediated DNA cleavage. Despite its wide use, etoposide is associated with some very serious side-effects including the development of treatment-related acute myelogenous leukemias. Etoposide targets both human topoisomerase IIα and IIβ. However, the contributions of the two enzyme isoforms to the therapeutic vs. leukemogenic properties of the drug are unclear. In order to develop an etoposide-based drug with specificity for cancer cells that express an active polyamine transport system, the sugar moiety of the drug has been replaced with a polyamine tail. To analyze the effects of this substitution on the specificity of hybrid molecules toward the two enzyme isoforms, we analyzed the activity of a series of etoposide-polyamine hybrids toward human topoisomerase IIα and IIβ. All of the compounds displayed an ability to induce enzyme-mediated DNA cleavage that was comparable to or higher than that of etoposide. Relative to the parent drug, the hybrid compounds displayed substantially higher activity toward topoisomerase IIβ than IIα. Modeling studies suggest that the enhanced specificity may result from interactions with Gln778 in topoisomerase IIβ. The corresponding residue in the α isoform is a methionine.

Everolimus exhibits anti-tumorigenic activity in obesity-induced ovarian cancer

Everolimus inhibits mTOR kinase activity and its downstream targets by acting on mTORC1 and has anti-tumorigenic activity in ovarian cancer. Clinical and epidemiologic data find that obesity is associated with worse outcomes in ovarian cancer. In addition, obesity leads to hyperactivation of the mTOR pathway in epithelial tissues, suggesting that mTOR inhibitors may be a logical choice for treatment in obesity-driven cancers. However, it remains unclear if obesity impacts the effect of everolimus on tumor growth in ovarian cancer. The present study was aimed at evaluating the effects of everolimus on cytotoxicity, cell metabolism, apoptosis, cell cycle, cell stress and invasion in human ovarian cancer cells. A genetically engineered mouse model of serous ovarian cancer fed a high fat diet or low fat diet allowed further investigation into the inter-relationship between everolimus and obesity in vivo. Everolimus significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, reduced invasion and caused cellular stress via inhibition of mTOR pathways in vitro. Hypoglycemic conditions enhanced the sensitivity of cells to everolimus through the disruption of glycolysis. Moreover, everolimus was found to inhibit ovarian tumor growth in both obese and lean mice. This reduction coincided with a decrease in expression of Ki-67 and phosphorylated-S6, as well as an increase in cleaved caspase 3 and phosphorylated-AKT. Metabolite profiling revealed that everolimus was able to alter tumor metabolism through different metabolic pathways in the obese and lean mice. Our findings support that everolimus may be a promising therapeutic agent for obesity-driven ovarian cancers.

The DNA-Binding Polyamine Moiety in the Vectorized DNA Topoisomerase II Inhibitor F14512 Alters Reparability of the Consequent Enzyme-Linked DNA Double-Strand Breaks

Poisons of topoisomerase II (TOP2) kill cancer cells by preventing religation of intermediate DNA breaks during the enzymatic process and thus by accumulating enzyme-drug-DNA complexes called TOP2 cleavage-complex (TOP2cc). F14512 is a highly cytotoxic polyamine-vectorized TOP2 inhibitor derived from etoposide and currently in clinical trials. It was shown in vitro that F14512 has acquired DNA-binding properties and that the stability of TOP2cc was strongly increased. Paradoxically, at equitoxic concentrations in cells, F14512 induced less DNA breaks than etoposide. Here, we directly compared etoposide and F14512 for their rates of TOP2cc production and resolution in human cells. We report that targeting of TOP2α and not TOP2β impacts cell killing by F14512, contrary to etoposide that kills cells through targeting both isoforms. Then, we show that despite being more cytotoxic, F14512 is less efficient than etoposide at producing TOP2α cleavage-complex (TOP2αcc) in cells. Finally, we report that compared with TOP2αcc mediated by etoposide, those generated by F14512 persist longer in the genome, are not dependent on TDP2 for cleaning break ends from TOP2α, are channeled to a larger extent to resection-based repair processes relying on CtIP and BRCA1 and promote RAD51 recruitment to damaged chromatin. In addition to the addressing of F14512 to the polyamine transport system, the properties uncovered here would be particularly valuable for a therapeutic usage of this new anticancer compound. More generally, the concept of increasing drug cytotoxicity by switching the repair mode of the induced DNA lesions via addition of a DNA-binding moiety deserves further developments. Mol Cancer Ther; 16(10); 2166-77. ©2017 AACR.

Dose escalation study to evaluate safety, tolerability and efficacy of intravenous etoposide phosphate administration in 27 dogs with multicentric lymphoma

Comparative oncology has shown that naturally occurring canine cancers are of valuable and translatable interest for the understanding of human cancer biology and the characterization of new therapies. This work was part of a comparative oncology project assessing a new, clinical-stage topoisomerase II inhibitor and comparing it with etoposide in dogs with spontaneous lymphoma with the objective to translate findings from dogs to humans. Etoposide is a topoisomerase II inhibitor widely used in various humans' solid and hematopoietic cancer, but little data is available concerning its potential antitumor efficacy in dogs. Etoposide phosphate is a water-soluble prodrug of etoposide which is expected to be better tolerated in dogs. The objectives of this study were to assess the safety, the tolerability and the efficacy of intravenous etoposide phosphate in dogs with multicentric lymphoma. Seven dose levels were evaluated in a traditional 3+3 phase I design. Twenty-seven owned-dogs with high-grade multicentric lymphoma were enrolled and treated with three cycles of etoposide phosphate IV injections every 2 weeks. Adverse effects were graded according to the Veterinary Cooperative Oncology Group criteria. A complete end-staging was realized 45 days after inclusion. The maximal tolerated dose was 300 mg/m2. At this dose level, the overall response rate was 83.3% (n = 6, 3 PR and 2 CR). Only a moderate reversible gastrointestinal toxicity, no severe myelotoxicity and no hypersensitivity reaction were reported at this dose level. Beyond the characterization of etoposide clinical efficacy in dogs, this study underlined the clinical and therapeutic homologies between dog and human lymphomas.

Synthesis and evaluation of biological properties of ferrocenyl–podophyllotoxin conjugates

Ferrocenyl–podophyllotoxin conjugates have been synthesised and their antiproliferative activity, influence on cell cycle, and interactions with tubulin were evaluated.

Synthesis and Biological Evaluation of Novel Aromatic Imide-Polyamine Conjugates

Three types of conjugates in which aromatic imide scaffolds were coupled to diverse amine/polyamine motifs were synthesized, and their antitumor activities were evaluated in vitro and in vivo. Results showed that the conjugate 11e of 1,8-naphthilimide with spermine had pronounced effects on inhibiting tumor cell proliferation and inducing tumor cell apoptosis via ROS-mediated mitochondrial pathway. The in vivo assays on three H22 tumor transplant models revealed that compound 11e exerted potent ability in preventing lung cancer metastasis and extending lifespan. Furthermore, the efficacy of 11e in inhibiting tumor growth and improving body weight index were better than that of positive control, amonafide. Our study demonstrates that compound 11e is a valuable lead compound for further investigation.

Cancer Drug Development Using Drosophila as an in vivo Tool: From Bedside to Bench and Back

The fruit fly Drosophila melanogaster has been used for modeling cancer and as an in vivo tool for the validation and/or development of cancer therapeutics. The impetus for the use of Drosophila in cancer research stems from the high conservation of its signaling pathways, lower genetic redundancy, short life cycle, genetic amenability, and ease of maintenance. Several cell signaling pathways in Drosophila have been used for cancer drug development. The efficacy of combination therapy and uptake/bioavailability of drugs have also been studied. Drosophila has been validated using several FDA-approved drugs, suggesting a potential application of this model in drug repurposing. The model is emerging as a powerful tool for high-throughput screening and should significantly reduce the cost and time associated with drug development. In this review we discuss the applications of Drosophila in cancer drug development. The advantages and limitations of the model are discussed.

F14512, a polyamine-vectorized inhibitor of topoisomerase II, exhibits a marked anti-tumor activity in ovarian cancer

Epithelial ovarian cancer is the fourth cause of death among cancer-bearing women and frequently associated with carboplatin resistance, underlining the need for more efficient and targeted therapies. F14512 is an epipodophylotoxin-core linked to a spermine chain which enters cells via the polyamine transport system (PTS). Here, we investigate this novel concept of vectorization in ovarian cancer. We compared the effects of etoposide and F14512 on a panel of five carboplatin-sensitive or resistant ovarian cancer models. We assessed the incorporation of F17073, a spermine-linked fluorescent probe, in these cells and in 18 clinical samples. We then showed that F14512 exhibits a high anti-proliferative and pro-apoptotic activity, particularly in cells with high levels of F17073 incorporation. Consistently, F14512 significantly inhibited tumor growth compared to etoposide, in a cisplatin-resistant A2780R subcutaneous model, at a dose of 1.25 mg/kg. In addition, ex vivo analysis indicated that 15 out of 18 patients presented a higher F17073 incorporation into tumor cells compared to normal cells. Overall, our data suggest that F14512, a targeted drug with a potent anti-tumor efficacy, constitutes a potential new therapy for highly PTS-positive and platinum-resistant ovarian cancer-bearing patients.