Enhancing Pt (IV) Complexes Anticancer Activity Upon Encapsulation in Stimuli Responsive Nanocages

Platinum-based chemotherapy is the first-line treatment for different cancer types and in particular for malignant pleural mesothelioma patients (a tumor histotype with urgent medical needs). Herein we present a strategy to stabilize, transport and intracellular release of a platinum^IV (Pt^IV ) prodrug using a breakable nanocarrier. Its reduction, and therefore activation as anticancer drug, is promoted by the presence of glutathione in neoplastic cells that also causes the destruction of the carrier. The nanocage presents a single internal cavity in which the hydrophobic complex (Pt(dach)Cl₂ (OH)₂ ), (dach = R,R-diaminocyclohexane) has been encapsulated. We have evaluated the in vitro uptake and the internalization kinetics in cancer model cells and using flow cytometry analysis, demonstrated the successful release and activation of the Pt based drug inside cancer cells. The in vitro findings were confirmed by the in vivo experiments on a mice model obtained by xenografting MPM487, a patient-derived malignant pleural mesothelioma. MPM487 confirmed the well-known resistance of malignant pleural mesothelioma to cisplatin treatment while an interesting 50% reduction of tumor growth was observed when mice were treated with the Pt^IV , entrapped in the nanocages, at an equivalent dose of platinum complex. This article is protected by copyright. All rights reserved.

Quantitative measurement of pioglitazone in neoplastic and normal tissues by AP-MALDI mass spectrometry imaging

Pioglitazone is a Peroxisome Proliferator-Activated Receptor (PPAR) agonist of the thiazolidinedione class of compounds with promising anticancer activity. An innovative quantitative mass spectrometry imaging (MSI) method and a HPLC-UV method were developed and validated to investigate its distribution in tumor and liver tissues. The MSI method is based on stable isotope normalization and resulted highly specific and sensitive (0.2 pmol/spot). The correct identification of the drug ion signal is confirmed by MS/MS analysis on tissue. The method shows an optimal lateral resolution (25 μm) relying on the ionization efficiency and fine laser diameter of the atmospheric pressure MALDI source. The HPLC-UV method is simple and straightforward involving quick protein precipitation and shows good sensitivity (50ng/sample) using a small starting volume of biological sample. Thus, it is applicable to samples obtained from both preclinical models and clinical surgical procedures. MSI and HPLC-UV assays were validated assessing linearity, intra- and inter-day precision and accuracy, limit of quantification, selectivity and recovery. These are the first methods developed and validated for the analysis of pioglitazone in tissues, and they were applied successfully to myxoid liposarcoma xenograft-bearing mice, which received clinically relevant drug doses. Pioglitazone was measured by either method in sections of tumor and liver 2, 6 and 24 h post-treatment. Drug distribution was relatively homogeneous.

Mechanisms of responsiveness to and resistance against trabectedin in murine models of human myxoid liposarcoma

Myxoid liposarcoma (MLPS) is a rare soft-tissue sarcoma characterised by the expression of FUS-DDIT3 chimera. Trabectedin has shown significant clinical anti-tumour activity against MLPS. To characterise the molecular mechanism of trabectedin sensitivity and of resistance against it, we integrated genomic and transcriptomic data from treated mice bearing ML017 or ML017/ET, two patient-derived MLPS xenograft models, sensitive to and resistant against trabectedin, respectively. Longitudinal RNA-Seq analysis of ML017 showed that trabectedin acts mainly as a transcriptional regulator: 15 days after the third dose trabectedin modulates the transcription of 4883 genes involved in processes that sustain adipocyte differentiation. No such differences were observed in ML017/ET. Genomic analysis showed that prolonged treatment causes losses in 4p15.2, 4p16.3 and 17q21.3 cytobands leading to acquired-resistance against the drug. The results dissect the complex mechanism of action of trabectedin and provide the basis for novel combinatorial approaches for the treatment of MLPS that could overcome drug-resistance.

Trabectedin and Lurbinectedin Extend Survival of Mice Bearing C26 Colon Adenocarcinoma, without Affecting Tumor Growth or Cachexia

Trabectedin (ET743) and lurbinectedin (PM01183) limit the production of inflammatory cytokines that are elevated during cancer cachexia. Mice carrying C26 colon adenocarcinoma display cachexia (i.e., premature death and body wasting with muscle, fat and cardiac tissue depletion), high levels of inflammatory cytokines and subsequent splenomegaly. We tested whether such drugs protected these mice from cachexia. Ten-week-old mice were inoculated with C26 cells and three days later randomized to receive intravenously vehicle or 0.05 mg/kg ET743 or 0.07 mg/kg PM01183, three times a week for three weeks. ET743 or PM01183 extended the lifespan of C26-mice by 30% or 85%, respectively, without affecting tumor growth or food intake. Within 13 days from C26 implant, both drugs did not protect fat, muscle and heart from cachexia. Since PM01183 extended the animal survival more than ET743, we analyzed PM01183 further. In tibialis anterior of C26-mice, but not in atrophying myotubes, PM01183 restrained the NF-κB/PAX7/myogenin axis, possibly reducing the pro-inflammatory milieu, and failed to limit the C/EBPβ/atrogin-1 axis. Inflammation-mediated splenomegaly of C26-mice was inhibited by PM01183 for as long as the treatment lasted, without reducing IL-6, M-CSF or IL-1β in plasma. ET743 and PM01183 extend the survival of C26-bearing mice unchanging tumor growth or cachexia but possibly restrain muscle-related inflammation and C26-induced splenomegaly.

Combination of PPARγ Agonist Pioglitazone and Trabectedin Induce Adipocyte Differentiation to Overcome Trabectedin Resistance in Myxoid Liposarcomas

PURPOSE

This study was aimed at investigating whether the PPARγ agonist pioglitazone-given in combination with trabectedin-is able to reactivate adipocytic differentiation in myxoid liposarcoma (MLS) patient-derived xenografts, overcoming resistance to trabectedin.

EXPERIMENTAL DESIGN

The antitumor and biological effects of trabectedin, pioglitazone, and the combination of the two drugs were investigated in nude mice bearing well-characterized MLS xenografts representative of innate or acquired resistance against trabectedin. Pioglitazone and trabectedin were given by daily oral and weekly i.v. administrations, respectively. Molecular studies were performed by using microarrays approach, real-time PCR, and Western blotting.

RESULTS

We found that the resistance of MLS against trabectedin is associated with the lack of activation of adipogenesis. The PPARγ agonist pioglitazone reactivated adipogenesis, assessed by histologic and gene pathway analyses. Pioglitazone was well tolerated and did not increase the toxicity of trabectedin. The ability of pioglitazone to reactivate adipocytic differentiation was observed by morphologic examination, and it is consistent with the increased expression of genes such as ADIPOQ implicated in the adipogenesis process. The determination of adiponectin by Western blotting constitutes a good and reliable biomarker related to MLS adipocytic differentiation.

CONCLUSIONS

The finding that the combination of pioglitazone and trabectedin induces terminal adipocytic differentiation of some MLSs with the complete pathologic response and cure of tumor-bearing mice provides a strong rationale to test the combination of trabectedin and pioglitazone in patients with MLS.

A novel oral micellar fenretinide formulation with enhanced bioavailability and antitumour activity against multiple tumours from cancer stem cells

Background

An increasing number of anticancer agents has been proposed in recent years with the attempt to overcome treatment-resistant cancer cells and particularly cancer stem cells (CSC), the major culprits for tumour resistance and recurrence. However, a huge obstacle to treatment success is the ineffective delivery of drugs within the tumour environment due to limited solubility, short circulation time or inconsistent stability of compounds that, together with concomitant dose-limiting systemic toxicity, contribute to hamper the achievement of therapeutic drug concentrations. The synthetic retinoid Fenretinide (4-hydroxy (phenyl)retinamide; 4-HPR) formerly emerged as a promising anticancer agent based on pre-clinical and clinical studies. However, a major limitation of fenretinide is traditionally represented by its poor aqueous solubility/bioavailability due to its hydrophobic nature, that undermined the clinical success of previous clinical trials.

Methods

Here, we developed a novel nano-micellar fenretinide formulation called bionanofenretinide (Bio-nFeR), based on drug encapsulation in an ion-pair stabilized lipid matrix, with the aim to raise fenretinide bioavailability and antitumour efficacy.

Results

Bio-nFeR displayed marked antitumour activity against lung, colon and melanoma CSC both in vitro and in tumour xenografts, in absence of mice toxicity. Bio-nFeR is suitable for oral administration, reaching therapeutic concentrations within tumours and an unprecedented therapeutic activity in vivo as single agent.

Conclusion

Altogether, our results indicate Bio-nFeR as a novel anticancer agent with low toxicity and high activity against tumourigenic cells, potentially useful for the treatment of solid tumours of multiple origin.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1383-9) contains supplementary material, which is available to authorized users.

Establishment and characterisation of a new patient-derived model of myxoid liposarcoma with acquired resistance to trabectedin

BACKGROUND

Myxoid liposarcoma is a histological subtype of liposarcoma particularly sensitive to trabectedin. In clinical use this drug does not cause cumulative toxicity, allowing prolonged treatment, generally until disease progression. No other effective therapies are available for trabectedin-resistant patients.

METHODS

Through repeated in vivo treatment in athymic nude mice, we have obtained a patient-derived xenograft with acquired resistance to trabectedin.

RESULTS

At basal level, the morphology of the resistant and sensitive models did not differ, in keeping with the finding that the transcriptional profiles of the resistant and sensitive tumours were very similar. After trabectedin treatment adipogenesis was induced in the parental xenograft but not in the resistant one, as assessed by pathological and molecular analysis. A defective transcription-coupled-nucleotide excision repair in the resistant tumour due to mutation of the UVSSA gene may be implicated in the mechanism of resistance.

CONCLUSIONS

This is the first in vivo model of myxoid liposarcoma with acquired resistance to trabectedin. Although further studies are necessary to characterise the resistance mechanisms, this is a useful tool for studying new therapeutic strategies to overcome trabectedin resistance in patients.

Lurbinectedin reduces tumour-associated macrophages and the inflammatory tumour microenvironment in preclinical models

Background:

Lurbinectedin is a novel anticancer agent currently undergoing late-stage (Phase II /III) clinical evaluation in platinum-resistant ovarian, BRCA1/2-mutated breast and small-cell lung cancer. Lurbinectedin is structurally related to trabectedin and it inhibits active transcription and the DNA repair machinery in tumour cells.

Methods:

In this study we investigated whether lurbinectedin has the ability to modulate the inflammatory microenvironment and the viability of myeloid cells in tumour-bearing mice.

Results:

Administration of lurbinectedin significantly and selectively decreased the number of circulating monocytes and, in tumour tissues, that of macrophages and vessels. Similar findings were observed when a lurbinectedin-resistant tumour variant was used, indicating a direct effect of lurbinectedin on the tumour microenviroment. In vitro, lurbinectedin induced caspase-8-dependent apoptosis of human purified monocytes, whereas at low doses it significantly inhibited the production of inflammatory/growth factors (CCL2, CXCL8 and VEGF) and dramatically impaired monocyte adhesion and migration ability. These findings were supported by the strong inhibition of genes of the Rho-GTPase family in lurbinectedin-treated monocytes.

Conclusions:

The results illustrate that lurbinectedin affects at multiple levels the inflammatory microenvironment by acting on the viability and functional activity of mononuclear phagocytes. These peculiar effects, combined with its intrinsic activity against cancer cells, make lurbinectedin a compound of particular interest in oncology.

A covalent PIN1 inhibitor selectively targets cancer cells by a dual mechanism of action

The prolyl isomerase PIN1, a critical modifier of multiple signalling pathways, is overexpressed in the majority of cancers and its activity strongly contributes to tumour initiation and progression. Inactivation of PIN1 function conversely curbs tumour growth and cancer stem cell expansion, restores chemosensitivity and blocks metastatic spread, thus providing the rationale for a therapeutic strategy based on PIN1 inhibition. Notwithstanding, potent PIN1 inhibitors are still missing from the arsenal of anti-cancer drugs. By a mechanism-based screening, we have identified a novel covalent PIN1 inhibitor, KPT-6566, able to selectively inhibit PIN1 and target it for degradation. We demonstrate that KPT-6566 covalently binds to the catalytic site of PIN1. This interaction results in the release of a quinone-mimicking drug that generates reactive oxygen species and DNA damage, inducing cell death specifically in cancer cells. Accordingly, KPT-6566 treatment impairs PIN1-dependent cancer phenotypes in vitro and growth of lung metastasis in vivo.

PIN1 is a promising therapeutic target for cancer treatment. In this study, the authors identify a covalent inhibitor of PIN1 with anti-tumour and anti-metastatic properties thanks to PIN1 inactivation and to the release, after binding to PIN1, of a quinone-mimicking compound that elicits reactive oxygen generation and causes DNA damage.

Antitumour activity of trabectedin in myelodysplastic/myeloproliferative neoplasms

BACKGROUND

Juvenile myelomonocytic leukaemia (JMML) and chronic myelomonocytic leukaemia (CMML) are myelodysplastic myeloproliferative (MDS/MPN) neoplasms with unfavourable prognosis and without effective chemotherapy treatment. Trabectedin is a DNA minor groove binder acting as a modulator of transcription and interfering with DNA repair mechanisms; it causes selective depletion of cells of the myelomonocytic lineage. We hypothesised that trabectedin might have an antitumour effect on MDS/MPN.

METHODS

Malignant CD14+ monocytes and CD34+ haematopoietic progenitor cells were isolated from peripheral blood/bone marrow mononuclear cells. The inhibition of CFU-GM colonies and the apoptotic effect on CD14+ and CD34+ induced by trabectedin were evaluated. Trabectedin's effects were also investigated in vitro on THP-1, and in vitro and in vivo on MV-4-11 cell lines.

RESULTS

On CMML/JMML cells, obtained from 20 patients with CMML and 13 patients with JMML, trabectedin - at concentration pharmacologically reasonable, 1-5 nM - strongly induced apoptosis and inhibition of growth of haematopoietic progenitors (CFU-GM). In these leukaemic cells, trabectedin downregulated the expression of genes belonging to the Rho GTPases pathway (RAS superfamily) having a critical role in cell growth and cytoskeletal dynamics. Its selective activity on myelomonocytic malignant cells was confirmed also on in vitro THP-1 cell line and on in vitro and in vivo MV-4-11 cell line models.

CONCLUSIONS

Trabectedin could be good candidate for clinical studies in JMML/CMML patients.

In Vitro and In Vivo Activity of Lucitanib in FGFR1/2 Amplified or Mutated Cancer Models

The fibroblast growth factor receptor (FGFR) pathway has been implicated both as an escape mechanism from anti-angiogenic therapy and as a driver oncogene in different tumor types. Lucitanib is a small molecule inhibitor of vascular endothelial growth factor (VEGF) receptors 1 to 3 (VEGFR1 to 3), platelet derived growth factor α/β (PDGFRα/β) and FGFR1–3 tyrosine kinases and has demonstrated activity in a phase I/II clinical study, with objective RECIST responses in breast cancer patients with FGFR1 or FGF3/4/19 gene amplification, as well as in patients anticipated to benefit from anti-angiogenic agents. We report here the in vitro and in vivo antitumor activity of lucitanib in experimental models with or without FGFR1/2 amplification or mutations. In cell assays, lucitanib potently inhibited the growth of tumor cell lines with amplified FGFR1 or mutated/amplified FGFR2. In all xenograft models studied, lucitanib demonstrated marked tumor growth inhibition due to potent inhibition of angiogenesis. Notably, in two lung cancer models with FGFR1 amplification, the antitumor efficacy was higher, suggesting that the simultaneous inhibition of VEGF and FGF receptors in FGFR1 dependent tumors can be therapeutically advantageous. Similar antitumor activity was observed in FGFR2 wild-type and amplified or mutated xenograft models. Pharmacokinetic studies showed lucitanib plasma concentrations in the micro/sub-micromolar range demonstrated drug accumulation following repeated lucitanib administration.

Promising in vivo efficacy of the BET bromodomain inhibitor OTX015/MK-8628 in malignant pleural mesothelioma xenografts

It has recently been reported that a large proportion of human malignant pleural mesothelioma (MPM) cell lines and patient tissue samples present high expression of the c-MYC oncogene. This gene drives several tumorigenic processes and is overexpressed in many cancers. Although c-MYC is a strategic target to restrain cancer processes, no drugs acting as c-MYC inhibitors are available. The novel thienotriazolodiazepine small-molecule bromodomain inhibitor OTX015/MK-8628 has shown potent antiproliferative activity accompanied by c-MYC downregulation in several tumor types. This study was designed to evaluate the growth inhibitory effect of OTX015 on patient-derived MPM473, MPM487 and MPM60 mesothelioma cell lines and its antitumor activity in three patient-derived xenograft models, MPM473, MPM487 and MPM484, comparing it with cisplatin, gemcitabine and pemetrexed, three agents which are currently used to treat MPM in the clinic. OTX015 caused a significant delay in cell growth both in vitro and in vivo. It was the most effective drug in MPM473 xenografts and showed a similar level of activity as the most efficient treatment in the other two MPM models (gemcitabine in MPM487 and cisplatin in MPM484). In vitro studies showed that OTX015 downregulated c-MYC protein levels in both MPM473 and MPM487 cell lines. Our findings represent the first evidence of promising therapeutic activity of OTX015 in mesothelioma.

Abstract 1183: PPARgamma agonist promotes adipocytic differentiation and potentiates the activity of trabectedin in myxoid liposarcoma

Trabectedin (ET-743, Yondelis) is a marine alkaloid isolated from the tunicate Ecteinascidia turbinata, approved in Europe and US for the 2nd line therapy of soft tissue sarcomas. It is particularly effective against myxoid liposarcoma, a specific histological subtype within the family of adults soft tissue sarcomas. More than 90% of usual myxoid/round cell liposarcomas (MRCLS) are characterized by the chromosomal translocation t(12;16) (q13; p11), which produces the FUS-CHOP oncogene. Different chimera subtypes seem to respond differently to trabectedin in clinical setting. Trabectedin was able to remove FUS-CHOP type I, II and III from its own target genes but it causes adipocytic maturation and tumor regression only in type I and II, not in type III MRCLS (Di Giandomenico et al, Oncogene, 2014 Oct 30; 33(44): 5201-10). Pioglitazone is a PPARgamma agonist with pro-differentiation effects in different cancer types included liposarcomas (Tontonoz P. et al, Proc Natl Acad Sci U S A. 1997 Jan 7;94(1): 237-41).

The aim of the study is to evaluate the efficacy of the combination of trabectedin with pioglitazone in type III myxoid liposarcoma xenografts.

ML006 and ML004 type III MRCLS xenografts mice were treated with trabectedin 0.15 mg/kg iv every seven days for three times or pioglitazone 150 mg/kg po daily for 28 days or with their combination. For antitumor activity evaluation, tumor growth was measured with a caliper and the tumor weights (1 mm3 = 1 mg) were calculated with the formula: length × (width)2/2. Fifteen days after the last dose of trabectedin and 4 h after the last dose of pioglitazone tumors were collected from a separate group of mice to perform histological and molecular analyses.

Trabectedin and pioglitazone as single agents have a comparable antitumor activity on these models with T/C around 40-50% with no tumor regression observed. In the combination groups an impressive and long lasting tumor regression was observed in ML 006 xenograft, with an observed optimal T/C of 17%. In ML004 MRCLS model the combination of trabectedin and pioglitazone induced a minimal regression followed by a long lasting tumor stabilization, resulting in a T/C of 23%. The histological analyses showed adipocytic maturation in tumors treated with pioglitazone alone or in combination but not in samples from mice treated with trabectedin alone.

In conclusion, the combination of trabectedin with pioglitazone was able to induce tumor regression and adipocytic maturation in type III myxoid liposarcoma xenografts that were only marginally sensitive to trabectedin alone. Chromatin Immunoprecipitation, gene expression profile and Western Blot analysis are on-going to unravel the molecular mechanism behind the potentiation of the antitumor efficacy observed with this combination.

Citation Format: Ezia Bello, Roberta Frapolli, Simonetta Andrea Licandro, Silvia Brich, Laura Carrassa, Roberta Sanfilippo, Alessandro Gronchi, Paolo Casali, Silvana Pilotti, Maurizio D’Incalci. PPARgamma agonist promotes adipocytic differentiation and potentiates the activity of trabectedin in myxoid liposarcoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1183.

Abstract 3764: Trabectedin activity in patient-derived mesothelioma xenografts

Malignant pleural mesothelioma (MPM) incidence is increased over the past two decades and it is predicted to increase further in the next 20 years especially in developing countries where asbestos has not yet been banned. Surgery is not an option for the majority of patients due to the diffuse growth of MPM, making chemotherapy the treatment of choice, but prognosis remains very poor with a median survival time of 10-17 months. Trabectedin (ET-743, Yondelis) is a marine alkaloid used for the 2nd line therapy of ovarian cancer (combined with pegylated doxorubicin) and soft tissue sarcomas. It binds the DNA minor groove modulating transcription of cancer cells and has an anti-inflammatory effect modifying tumor microenvironment and reducing tumor associated macrophages.

The aim was to test antitumor activity of trabectedin in newly established patient derived xenografts of MPM.

MPM473, MPM484 and MPM487 xenografts were obtained in athymic nude mice by s.c. injection of 107 cells isolated from the pleural effusion of MPM patients and maintained by serial passages in mice. H&E staining and immunohistochemistry were performed. Mice were randomized when tumor reached about 200 mg to receive trabectedin, cisplatin, pemetrexed, gemcitabine, and imatinib. Antitumor activity was expressed as T/C% were T and C are the mean tumor weight of treated and control mice, respectively.

The three xenografts reproduced the morphology and the histochemical profile of the human tumors. As reported in the table trabectedin was able to induce a 50% reduction in tumor growth in MPM473 and MPM 487 xenografts and only a marginal effect in MPM484 xenograft. TreatmentDose (mg/kg)ScheduleBest T/C% (Day)MPM473MPM484MPM487Cisplatin5i.v. q7dx361.9 (69)66.1 (69)67.3 (39)Gemcitabine100i.p. q4dx583.2 (41)67.7 (48)49.7 (56)Imatinib200p.o. qdx1568.9 (76)89.4 (55)87.1 (39)Pemetrexed250i.p. q4dx477.4 (52)76.8 (49)84.3 (39)Trabectedin0.15i.v. q7dx351.0 (73)63.6 (69)51.3 (56)

In conclusion we report three new MPM xenografts able to mimic the pathological features of human MPM. Although trabectedin showed only a moderate antitumor activity in our experimental models, its efficacy is comparable or better than that of the other drugs currently used for this disease. Studies are in progress in syngenic models that are more appropriate to test also the ability of trabectedin to modulate the immune system.

Citation Format: Simonetta Andrea Licandro, Roberta Frapolli, Ezia Bello, Roberta Libener, Sara Orecchia, Federica Grosso, Maurizio D’Incalci. Trabectedin activity in patient-derived mesothelioma xenografts. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3764.

Abstract 1284: Lurbinectedin reduces tumor-associated macrophages and the production of inflammatory cytokines, chemokines, and angiogenic factors in preclinical models

Lurbinectedin, currently undergoing clinical evaluation in ovarian, breast and small-cell lung cancer patients, inhibits active transcription. The drug is structurally related to trabectedin containing the same pentacyclic skeleton of the fused tetrahydroisoquinoline rings, but differing by the presence of a tetrahydro-B-carboline replacing the additional tetrahydroisoquinoline of trabectedin. We investigated whether lurbinectedin has the ability to regulate the inflammatory tumor microenvironment in vitro and in vivo. Human purified monocytes were highly sensitive to lurbinectedin (IC50: 5-10 nM) and, after drug treatment, underwent caspase-8-dependent apoptosis. Furthermore, in vitro, lurbinectedin significantly inhibited the production of selected inflammatory chemokines (CCL2, CXCL8) and VEGF by stimulated monocytes and liposarcoma cell lines. Administration of lurbinectedin to mice bearing a murine fibrosarcoma -resistant to this compound in vitro- resulted in significant anti-tumor activity (T/C value around 50%). The analysis of immune cells of blood spleen and tumor tissues during treatment with lurbinectedin revealed a significant and selective decrease in the subset of monocytes and macrophages, including tumor-associated macrophages (TAM). A gene expression analysis of monocytes treated with lurbinectedin indicated a modulation of the transcriptional program in LPS-stimulated human monocytes. Overall, these results indicate that lurbinectedin affects the inflammatory micro-environment, with a selective apoptotic-inducing effect on mononuclear phagocytes and a specific inhibition of production of inflammatory cytokines.

Citation Format: Paola Allavena, Cristina Belgiovine, Manuela Liguori, Ezia Bello, Roberta Frapolli, Carlos M. Galmarini, Maurizio D’Incalci. Lurbinectedin reduces tumor-associated macrophages and the production of inflammatory cytokines, chemokines, and angiogenic factors in preclinical models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1284.

Expression of thrombospondin-1 by tumor cells in patient-derived ovarian carcinoma xenografts

PURPOSE

Thrombospondin-1 (TSP-1), a major regulator of cell interaction with the environment, is often deregulated in cancers, including ovarian carcinoma. Both the tumor and the host cells can release TSP-1 in the tumor microenvironment. The relative contribution of the two sources in determining TSP-1 levels in ovarian cancer remains to be elucidated. This study was designed to investigate the expression of tumor TSP-1 in a panel of 29 patient-derived ovarian adenocarcinoma xenografts (PDX), using analytical tools specific for human (tumor-derived) rather than murine (host-derived) TSP-1.

METHODOLOGY

Human-specific microarray and ELISA were used to measure tumor TSP-1 expression and plasma levels.

RESULTS

Tumor-derived TSP-1 was heterogeneously expressed in PDX. Expression was higher in the corresponding original patient's tumor, where stroma-derived TSP-1 is also analyzed, indicating that both the tumor and the host contribute to TSP-1 production. TSP-1 was differentially expressed according to tumor grade, but not affected by p53 expression or mutational status. Findings were confirmed in an external gene expression dataset (101 patients). In a functional enrichment analysis, TSP-1 correlated with genes related to angiogenesis, cell motility, communication and shape. Plasma TSP-1, detectable in 10/11 PDX, was not associated to its expression in the tumor. The possible association of plasma TSP-1 with p53 mutations and response to chemotherapy warrants further investigation.

CONCLUSIONS

Ovarian carcinoma PDX are a useful tool to investigate the relative contribution of stroma and tumor cells in the production of tumor associated factors, in relation to the tumor behavior, molecular properties and response to therapy.

Abstract 2670: Exploring the in vitro and in vivo activity of lucitanib in FGFR1-amplified lung cancer models

Lucitanib (S80881, formerly E-3810) is a novel tyrosine kinase inhibitor that selectively inhibits vascular endothelial growth factor (VEGF) receptors 1-3 (VEGFR1-3) and fibroblast growth factor (FGF) receptor 1-2 (FGFR1-2). It exhibits a unique pharmacological profile and demonstrates potent antitumor activity in xenograft models derived from multiple oncology indications. The on-going phase I/II clinical study of lucitanib has demonstrated objective RECIST responses in breast cancer patients with FGF-aberrant (FGFR1 and/or FGF3/4/19 gene amplified) tumors and in oncology indications anticipated to benefit from antiangiogenic agents (e.g. renal cell and thyroid cancer patients).

In an attempt to further elucidate the mechanism of action of lucitanib, we evaluated the in vitro and in vivo activity of lucitanib in lung cell lines with FGFR1 amplification. The FGFR1 gene is frequently amplified in lung cancer tumors and FGFR1 copy number may provide a patient selection marker for clinical trials of FGFR inhibitors. Lucitanib cytotoxic activity was evaluated and compared to other FGFR inhibitors (Dovitinib, AZD4547 and PD173074) in a panel of 11 lung cancer cell lines characterized for FGFR1/2 gene copy number and FGFR1, FGFR2 and FGF2 mRNA expression level. Lucitanib IC50 values ranged from 0.14 to 23 μM; interestingly the two most sensitive cells lines (NCI-H1581 and DMS114) harbored FGFR1 amplification, while cell lines with lower FGFR1 gene copy number (≤2) displayed a higher drug IC50 value. In order to understand the involvement of FGFR1 inhibition in the antitumor activity of lucitanib, nude mice bearing FGFR1 amplified NCI-H1581 cell xenografts were treated with escalating doses of lucitanib (2.5, 5, 10 and 20mg/kg/day PO) continuously for 30 days. The antitumor activity of lucitanib at the dose of 2.5mg/kg was marginal (tumor volume of treated / control (T/C%) = 46), while at 5, 10 and 20mg/kg the drug was equally very active (T/C% = 24, 21 and 16, respectively). Pharmacodynamic and pharmacokinetic assessments were undertaken at the same drug doses employed for the xenograft efficacy experiments in NCI-H1581 tumor bearing mice treated for 12 continuous days. Tumor concentrations of lucitanib, measured by LC-MS/MS, were related to the administered dose and ranged from 0.31-3.68 μM and from 0.26-2.52 μM at 4 and 24hrs, respectively. Lucitanib drug concentrations were higher in the tumor than in the plasma, with tumor/plasma ratios at 4 and 24 hrs of 2.0±0.22 and 20.5±6, respectively. In conclusion, these preclinical data indicate that lucitanib demonstrates in vitro efficacy in lung cancer cell lines with FGFR1 gene amplification and has a favorable drug distribution profile in tumor models.

Citation Format: Ezia Bello, Rosaria Chilà, Federica Guffanti, Monique Zangarini, Laura Ceriani, Massimo Zucchetti, Saba Chaudi, Marie-Jeanne Pierrat, Anne Jacquet-Bescond, Giovanna L.M. Damia. Exploring the in vitro and in vivo activity of lucitanib in FGFR1-amplified lung cancer models. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2670. doi:10.1158/1538-7445.AM2014-2670

A biodistribution study of PEGylated PCL-based nanoparticles in C57BL/6 mice bearing B16/F10 melanoma

One of the major drawbacks that limits the clinical application of nanoparticles is the lack of preliminary investigations related to their biocompatibility, biodegradability and biodistribution. In this work, biodegradable PEGylated polymer nanoparticles (NPs) have been synthesized by using macromonomers based on poly(ε-caprolaconte) oligomers. More in detail, NPs have been produced by adopting a surfactant-free semibatch emulsion polymerization process using PEG chains as a stabilizing agent. The NPs were also labeled with rhodamine B covalently bound to the NPs to quantitatively study their biodistribution in vivo. NPs were investigated in both in vitro and in vivo preclinical systems to study their biodistribution in mice bearing B16/F10 melanoma, as well as their biocompatibility and biodegradability. The NP concentration was evaluated in different tissues at several times after intravenous injection. The disappearance of the NPs from the plasma was biphasic, with distribution and elimination half-lives of 30 min and 15 h, respectively. NPs were retained in tumors and in filter organs for a long time, were still detectable after 7 d and maintained a steady concentration in the tumor for 120 h. 48 h after injection, 70 ± 15% of the inoculated NPs were excreted in the feces. The favorable tumor uptake, fast excretion and absence of cytotoxicity foster the further development of produced NPs as drug delivery carriers.

HPLC-MS/MS method for quantitative determination of the novel dual inhibitor of FGF and VEGF receptors E-3810 in tumor tissues from xenograft mice and human biopsies

We developed and validated a high-performance liquid chromatography-tandem mass spectrometry analytical method to measure E-3810, a novel dual inhibitor of fibroblast growth factor receptor 1 and vascular endothelial growth factor receptor 1-3 in tissues and determined the drug concentration in a biopsy of human breast cancer for the first time. The method is a modification of our previous one in plasma to study the clinical pharmacokinetics of the drug during the phase I/II trial. In view of the changes in matrix, we applied a partial validation protocol to determine recovery, sensitivity, range of linearity, precision, accuracy and stability of the method over three runs in a mouse tumor tissue and liver. The recovery of E-3810 from liver or tumor homogenate was >69%, and the lower limit of quantification was 5 ng/ml. The method was linear in the concentration range 5.0-500.0 ng/ml, as demonstrated by a determination coefficient R(2) ≥ 0.9955. The range of the calibration curve was appropriate for the analysis, as demonstrated by the accuracy, which was between 91.4% and 106.7%. Interday precision and accuracy on quality control samples at 9, 30 and 300 ng/ml were 3.1-11.2% and 98.3-111.4%, respectively. The assay was applied successfully to determine the intratumor concentration of E-3810 in different mouse xenograft tumor models and in a biopsy of a patient with breast cancer included in the phase I/II trial of the drug. In mouse tumors, the concentrations of E-3810 were higher than necessary to exert antitumor activity in vitro (1 µM). Even more of interest was the result obtained in a human biopsy of few milligrams, where E-3810 reached 4.9 µg/g (11 µM).

Mode of action of trabectedin in myxoid liposarcomas

To elucidate the mechanisms behind the high sensitivity of myxoid/round cell liposarcoma (MRCL) to trabectedin and the suggested selectivity for specific subtypes, we have developed and characterized three MRCL xenografts, namely ML017, ML015 and ML004 differing for the break point of the fusion gene FUS-CHOP, respectively of type I, II and III. FUS-CHOP binding to the promoters of some target genes such as Pentraxin 3 or Fibronectin 1, assessed by chromatin immunoprecipitation, was strongly reduced in the tumor 24 h after the first or the third weekly dose of trabectedin, indicating that the drug at therapeutic doses causes a detachment of the FUS-CHOP chimera from its target promoters as previously shown in vitro. Moreover, the higher sensitivity of MRCL types I and II appears to be related to a more prolonged block of the transactivating activity of the fusion protein. Doxorubicin did not affect the binding of FUS-CHOP to target promoters. Histologically, the response to trabectedin in ML017 and ML015 was associated with a marked depletion of non-lipogenic tumoral cells and vascular component, as well as lipidic maturation as confirmed by PPARγ2 expression in western Blot. By contrast, in ML004 no major changes either in the cellularity or in the amount of mature were found, and consistently PPARγ2 was null. In conclusion, the data support the view that the selective mechanism of action of trabectedin in MRCL is specific and related to its ability to cause a functional inactivation of the oncogenic chimera with consequent derepression of the adypocytic differentiation.

Comparison of in vitro and in vivo biological effects of trabectedin, lurbinectedin (PM01183) and Zalypsis® (PM00104)

This study: (i) investigated the in vitro cytotoxicity and mode of action of lurbinectedin (PM01183) and Zalypsis® (PM00104) compared with trabectedin in cell lines deficient in specific mechanisms of repair, (ii) evaluated their in vivo antitumor activity against a series of murine tumors and human xenografts. The antiproliferative activity, the DNA damage and the cell cycle perturbations induced by the three compounds on tumor lines were very similar. Nucleotide Excision Repair (NER) deficient cells were approximately fourfold more resistant to trabectedin, lurbinectedin and Zalypsis®. Cells deficient in non-homologous end joining (NHEJ), MRN complex and translesion synthesis (TLS) were slightly more sensitive to the three compounds (approximately fivefold) while cells deficient in homologous recombination (HR) were markedly more sensitive (150-200-fold). All three compounds showed a good antitumor activity in several in vivo models. Lurbinectedin and trabectedin had a similar pattern of antitumor activity in murine tumors and in xenografts, whereas Zalypsis® appeared to have a distinct spectrum of activity. The fact that no relationship whatsoever was found between the in vitro cytotoxic potency and the in vivo antitumor activity, suggests that in addition to direct cytotoxic mechanisms other host-mediated effects are involved in the in vivo pharmacological effects.

The tyrosine kinase inhibitor E-3810 combined with paclitaxel inhibits the growth of advanced-stage triple-negative breast cancer xenografts

E-3810 is a novel small molecule that inhibits VEGF receptor-1, -2, and -3 and fibroblast growth factor receptor-1 tyrosine kinases at nmol/L concentrations currently in phase clinical II. In preclinical studies, it had a broad spectrum of antitumor activity when used as monotherapy in a variety of human xenografts. We here investigated the activity of E-3810 combined with different cytotoxic agents in a MDA-MB-231 triple-negative breast cancer xenograft model. The molecule could be safely administered with 5-fluorouracil, cisplatin, and paclitaxel. The E-3810-paclitaxel combination showed a striking activity with complete, lasting tumor regressions; the antitumor activity of the combination was also confirmed in another triple-negative breast xenograft, MX-1. The activity was superior to that of the combinations paclitaxel+brivanib and paclitaxel+sunitinib. Pharmacokinetics studies suggest that the extra antitumor activity of the combination is not due to higher paclitaxel tumor levels, which in fact were lower in mice pretreated with all three kinase inhibitors, and the paclitaxel plasma levels excluded reduced drug availability. Pharmacodynamic studies showed that E-3810, brivanib, and sunitinib given as single agents or in combination with paclitaxel reduced the number of vessels, but did not modify vessel maturation. Reduced tumor collagen IV and increased plasma collagen IV, associated with increased matrix metalloproteinases (MMP), particularly host MMP-9, indicate a proteolytic remodeling of the extracellular matrix caused by E-3810 that in conjunction with the cytotoxic effect of paclitaxel on the tumor cells (caspase-3/7 activity) may contribute to the striking activity of their combination. These data support the therapeutic potential of combining E-3810 with conventional chemotherapy.

Assessing the anti-tumour properties of Iraqi propolis in vitro and in vivo

The study was designed to evaluate anti-tumour properties of Iraqi propolis collected from Mosul region (M) on HL-60 and HCT-116 cell lines and on HCT-116 in vivo. M induced an inhibitory effect against the proliferation of HL-60 and colony potential of HCT-116 cells. The apoptosis in HL-60 cells was associated with down-regulation of Bcl-2 and activation of Bax, while in HCT-116 cells, necrotic features were observed; size of cells was dramatically increased by swelling of cytoplasm and loss of membrane integrity, cell rupture and release of cellular contents. Analysis of BrdU/DNA cell cycle in both cell lines showed that M induced cell cycle perturbations in both BrdU positive and BrdU negative cells. The exposure of HL-60 to M caused γ-H2AX in a dose dependent manner and was associated with induction of apoptosis. The experiments in HCT-116 tumor-bearing mice showed that oral administration of propolis at doses that caused no detectable toxicity was associated with a decrease in mitotic cells and an increase in endoreduplications, increased p53 and decreased Ki-67 expression of cells in tumor sections. This study provides the rationale to investigate the potential beneficial effect of propolis in the diet of patients receiving anti-cancer therapies.

Abstract A17: Mode of action of trabectedin in myxoid liposarcomas

Background: Trabectedin (ET-743, Yondelis) is a marine alkaloid isolated from the tunicate Ecteinascidia turbinata, cytotoxic against a variety of tumor cell lines in vitro and human tumor xenografts in vivo. It has been approved by EMEA for the 2nd line therapy of soft tissue sarcomas in 2007 and for the 2nd line therapy of ovarian cancer in 2009. Myxoid liposarcoma (MLS) is a specific histological subtype within the family of adults soft tissue sarcomas. Specifically >90% of usual myxoid/round cell liposarcomas (MLS/RCLS) are characterized by the chromosomal translocation t(12;16) (q13;p11), which produces the FUS-CHOP oncogene. Different variants of the fusion gene have been previously described but with no demonstrable prognostic effect although the type III MLS seem correlate with a more severe outcome than type II MLS.

Materials and Methods: To elucidate the mechanisms behind the differential sensitivity to trabectedin, myxoid liposarcomas type II and type III were xenografted in nude mice. When tumor load achieves about 200–400 mg mice were divided into the experimental groups. Trabectedin was administered at 0.15 mg/kg, i.v. every 7 days for three times. Tumor growth was monitored by Vernier caliper. The binding of FUS-CHOP to some of its target promoters was monitored by Chromatin Immuno Precipitation (ChIP) to verify the drug ability to displace the binding. ChIP were performed with ProtG Sepharose and the anti-FUS and anti-CHOP antibody. The immunoprecipitated DNAs were analyzed by quantitative Real Time PCR. FN1, PTX3, CDK4, IL8 and CHOP were used as target genes.

Results: We found that trabectedin was more effective on type II than type III MLS xenografts. The response to trabectedin in type II xenografts was associated with partial regression and pathological response. Type III MLS xenografts appeared much less sensitive to trabectedin and tumors did not regress. Molecular analysis revealed that trabectedin was able to remove FUS-CHOP type II and III from its own target genes 24 hours after treatment. 72 hours after treatment, FUS-CHOP Type III was attached to its targets whereas FUS-CHOP Type II remained unbound. These data explain why in order to achieve a significant regression of type III MLS xenografts a more prolonged treatment with trabectedin is required.

Conclusions: These results suggest that the different sensitivity of type II and type III MLS to trabectedin are related to a different duration of the drug ability to display FUS-CHOP from the selected target genes.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A17.

Abstract 2574: Striking activity of E-3810 combined with paclitaxel and 5FU in the triple negative breast cancer model MDA-MB-231

E-3810 is a novel small molecule that selectively inhibits VEGFR-1, -2 and -3 and FGFR-1 tyrosine kinases with IC50 <30nM; at higher nM concentrations it also inhibits FGFR-2. We have previously shown that the compound has a strong anti-angiogenic effects in vivo and displays potent antitumour activity in all the human xenograft models in which it has been tested. The compound is currently undergoing a Phase 1 clinical trial in Europe. To better characterize its pharmacological profile, combination studies with paclitaxel (PTX) and 5-Fluorouracil (5FU) were performed in the triple negative breast cancer tumor MDA-MB-231. Nude mice were transplanted subcutaneously with 7×106 MDA-MB-231 cells. When tumors reached 400 mg, animals were randomized to receive vehicle, PTX i.v. (20 mg/kg Q7×3), 5FU i.v. (100 mg/kg Q7×2), E-3810 p.o. (20 mg/kg daily for 30 days), the combination of PTX plus E-3810 and 5FU plus E-3810. Efficacy of the treatments was expressed as best tumor growth inhibition and tumor regression. The PTX combination regimen appeared as tolerated as the treatment with the two single agents (body weight loss less than 15% in the PTX+E-3810 group). The 5FU containing regimen resulted instead in enhanced toxicity with a remarkable weight loss (more than 20%) and 5/8 toxic deaths (as opposed to 1/8 in the group treated with 5FU only). 5FU as single agent had only a modest effect on MDA-MB-231 tumor growth, while PTX and E-3810 as single agents showed a good antitumor activity, with growth inhibition resulting in tumor stabilization. Outstanding activity with complete tumour regressions was observed in mice receiving the combination regimens: 7/8 and 2/3 complete regressions in the group treated with E-3810+PTX and with E-3810+ 5FU respectively at 150 days after tumor transplantation. In vitro, cytotoxic studies showed no synergistic activity when MDA-MB-231 cells were treated with E-3810 and the two drugs, suggesting that host mediated mechanisms are at the basis of the tumor cures observed in the in vivo model. Further experiments are undergoing to optimize the 5-FU+E3810 schedule and to investigate if the use of E-3810 in combination can modify drug pharmacokinetics. Moreover, the degree of apoptosis, necrosis, proliferation, ERK phosphorylation and CD31 and collagen IV positivity in tumors induced by the single agents and the combination treatments will be assessed and compared. in order to clarify the mechanism of the observed striking antitumor activity. These data suggest that E-3810 can be combined with anticancer agents with different mechanisms of action and that that the combinations can cure tumor-bearing mice, opening up the way to a possibly effective new clinical combinations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2574. doi:10.1158/1538-7445.AM2011-2574

E-3810 is a potent dual inhibitor of VEGFR and FGFR that exerts antitumor activity in multiple preclinical models

Tumor angiogenesis is a degenerate process regulated by a complex network of proangiogenic factors. Existing antiangiogenic drugs used in clinic are characterized by selectivity for specific factors. Antiangiogenic properties might be improved in drugs that target multiple factors and thereby address the inherent mechanistic degeneracy in angiogenesis. Vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF) family members and their cognate receptors are key players in promoting tumor angiogenesis. Here we report the pharmacologic profile of E-3810, a novel dual inhibitor of the VEGF and FGF receptors. E-3810 potently and selectively inhibited VEGF receptor (VEGFR)-1, -2, and -3 and FGF receptor (FGFR)-1 and -2 kinases in the nanomolar range. Ligand-dependent phosphorylation of VEGFR-2 and FGFR-1 was suppressed along with human vascular endothelial cell growth at nanomolar concentrations. In contrast, E-3810 lacked cytotoxic effects on cancer cell lines under millimolar concentrations. In a variety of tumor xenograft models, including early- or late-stage subcutaneous and orthotopic models, E-3810 exhibited striking antitumor properties at well-tolerated oral doses administered daily. We found that E-3810 remained active in tumors rendered nonresponsive to the general kinase inhibitor sunitinib resulting from a previous cycle of sunitinib treatment. In Matrigel plug assays performed in nude mice, E-3810 inhibited basic FGF-induced angiogenesis and reduced blood vessel density as assessed by histologic analysis. Dynamic contrast-enhanced magnetic resonance imaging analysis confirmed that E-3810 reduced the distribution of angiogenesis-sensitive contrast agents after only 5 days of treatment. Taken together, our findings identify E-3810 as a potent antiangiogenic small molecule with a favorable pharmacokinetic profile and broad spectrum antitumor activity, providing a strong rationale for its clinical evaluation.

Novel models of myxoid liposarcoma xenografts mimicking the biological and pharmacologic features of human tumors

PURPOSE

Myxoid liposarcoma is a common subtype of liposarcoma. It is associated in more than 90% of cases with the chromosomal translocation t(12;16)(q13;p11) leading to the fusion FUS-CHOP gene that is responsible for the oncogenic transformation of preadipocytes. Recently the marine natural product trabectedin has shown highly selective activity for myxoid liposarcoma, even in the most aggressive round-cell subtype.

EXPERIMENTAL DESIGN

Fragments of 17 sarcomas were transplanted s.c. in female athymic NCr-nu/nu mice. Xenografts were established and characterized by morphology, fluorescence in situ hybridization analysis for the translocation and reverse transcriptase-PCR analysis for fusion transcripts. Trabectedin was injected i.v.

RESULTS

Seven of 17 tumors grew as continuous xenografts, five of them being myxoid liposarcoma of the round-cell subtype. The chromosomal rearrangement and fusion transcripts in different passages were the same as in the human tumors from which they were derived. The responsiveness to trabectedin in type II myxoid liposarcoma xenografts was as high as in patients. The pathologic response was associated with the presence of the FUS-CHOP fusion gene, indicating that the drug does not totally eradicate the disease. Type III myxoid liposarcoma xenografts seemed much less sensitive to trabectedin, confirming previous clinical observations.

CONCLUSIONS

This study reports for the first time the characterization of human myxoid liposarcoma xenografts that adequately mimic the biological and pharmacologic features of the human tumor. These models offer a useful tool for investigating the mechanism of selectivity of trabectedin, testing new combinations with this drug and evaluating novel therapies for myxoid liposarcoma.

Clinical pharmacokinetics of the new oral camptothecin gimatecan: the inter-patient variability is related to alpha1-acid glycoprotein plasma levels

AIM OF THE STUDY

To determine the pharmacokinetics of gimatecan, a camptothecin with a lipophilic substitution in position 7, given orally to patients participating in the phase I study.

METHODS

Pharmacokinetics was evaluated in 78 patients after oral daily dose for 5 days a week for 1, 2 or 3 weeks by HPLC with a fluorescence detector.

RESULTS

Gimatecan was mainly present in plasma as lactone (>85%), the active form as DNA-topoisomerase I poison. The AUC(0-24) on the first day of treatment normalised per daily dose (mg/m(2)), ranged from 194 to 2909 ng h/mL/mg/m(2). The half-life was 77.1+/-29.6h, consequently C(max) and AUC rose 3-6-fold after multiple dosing. Multivariate analysis indicated the daily dose (p<0.0001) and the alpha(1)-acid glycoprotein (AGP) plasma levels (p<0.0001) as main predictors of gimatecan AUC(0-24). In the overall analysis, daily dose and AGP plasma levels explained 85% of the deviance. The hydroxy metabolite ST1698 was present in plasma at low levels with AUC values of 5-15% of gimatecan. In mice, orally treated with gimatecan, plasma and tissue levels were 2-fold higher after treatment with a pro-inflammatory agent causing AGP induction.

CONCLUSIONS

Gimatecan is orally absorbed and its variable plasma levels seem to be related to AGP plasma concentrations. Data obtained in mice, together with the fact that AGP levels largely exceeded gimatecan plasma concentrations, suggest that the increased gimatecan levels in patients with high AGP levels are not related to the binding of the drug to AGP with consequent reduced tissue drug distribution, but possibly to other mechanism associated with inflammation being AGP simply a marker of the inflammation process.

Abstract B198: The pattern of in vivo biological activity of Zalypsis® is different from that of trabectedin

Trabectedin is a tetrahydroisoquinoline molecule that was originally derived from the Caribbean marine tunicate Ectenaiscidia turbinata and is now produced by chemical synthesis. The compound is approved in the European Union and a number of other countries for use in patients with advanced soft tissue sarcomas. Zalypsis® (PM00104) is a novel synthetic tetrahydroisoquinoline structurally related to jorumycin. Both compounds have a similar A and B ring structures that bind DNA but differ in their C ring which protrudes out of DNA and is possibly relevant for the interaction with DNA binding proteins, including DNA repair proteins and transcription factors. In the present study, we characterized the in vivo antitumor activity compared to trabectedin. The antitumor activity of Zalypsis® was investigated in two murine models, M5076 reticulosarcoma and MNMCA1 fibrosarcoma, respectively metastasizing liver and lung. Zalypsis® (0.9 mg/kg) and trabectedin (0.15 mg/kg) were administered intravenously every week for three times (q7dx3). In both models Zalypsis® was very effective in inhibiting the primary tumors (T/C 18% and 20% respectively). In the case of MNMCA1, it was also effective against metastasis whereas it was inactive against liver metastasis of M5076 sarcoma. In the two experiments, trabectedin was very effective against metastasis although against M5076 sarcoma it was only marginally able to inhibit primary tumor growth (T/C 52%). In Cen3 tel sarcoma, of human origin, Zalypsis® was very effective with a T/C of 19% whereas trabectedin was essentially inactive (T/C 78%). In contrast Zalypsis® was less effective than trabectedin against HOC22 ovarian carcinoma. In summary it appears that Zalypsis® is biologically different from trabectedin when tested on in vivo tumor models, therefore its clinical development should not necessarily addressed to the same tumors that have shown sensitivity to trabectedin.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B198.

Biological Properties of IDN5174, a New Synthetic Camptothecin with the Open Lactone Ring

A series of water-soluble camptothecins obtained by linking a spermidine moiety to the 21-position of the open form through an amidic bond have been tested for their biochemical and biological activities. Growth inhibition assay on the human non-small cell lung cancer carcinoma NCI-H460 cell line revealed that the camptothecin analogues were less potent than topotecan and SN38 after 1 hour of treatment. The potency increased after 72 hours of exposure, being similar to that of reference camptothecins. The analysis of topoisomerase I-mediated DNA cleavage using the purified enzyme indicated that the novel camptothecin analogues retained ability to poison topoisomerase I and displayed the same cleavage pattern of SN38. Persistence of the DNA cleavage was comparable with that of SN38. Stabilization of the cleavable complex was not the result of hydrolysis of the N-C bond between polyamine and the drug because no free camptothecin was recovered at the end of DNA cleavage in presence of IDN5174, the analogue selected for detailed studies. IDN5174 exhibited an antitumor activity comparable with that of topotecan and irinotecan against NCI-H460 tumor xenograft. The pharmacokinetics in mice showed a favorable disposition in tumor tissue with low amount of camptothecin detectable in plasma and tumor (around 5-10%), thus supporting the efficacy of intact IDN5174. In conclusion, we found that IDN5174 maintained the biological and antitumor properties, in spite of lack of the closed E ring. The available results support the interpretation that the polyamine linked at the 21-position may allow a favorable drug interaction in the ternary complex.

Detection of tissue-specific effects by methotrexate on differentiating mouse embryonic stem cells

BACKGROUND

Pluripotent embryonic stem (ES) cells offer a unique possibility to monitor the differentiation of several cell types in vitro. This study attempts to identify marker genes during in vitro cell differentiation of murine ES cells and allow a prediction of chemical effects on cell differentiation of specific target tissues. The study focused on the expression pattern of key genes involved in cardiomyocyte and osteoblast differentiation: Oct-4, Brachyury, Nkx2.5, alpha myosin heavy chain, Cbfa1, and Osteocalcin.

METHODS

Methotrexate was selected due to its well-characterized teratogenic effects. Several in vivo studies have demonstrated the specific interactions of methotrexate with bone formation whereas the cardiovascular system is not specifically affected after exposure to low concentration. The capability of murine ES cells to differentiate in vitro into cardiomyocytes as well as into osteoblasts have been used to demonstrate the target cell specificity in vitro, at non-cytotoxic concentration.

RESULTS

Exposure of differentiating ES cells did not result in any gene profile modification of the selected cardiomyocyte specific genes, whereas the expression of osteoblast specific key genes, Cbfa1 and Osteocalcin, decreased. At the latter stages of skeletal differentiation we observed a 30% decrease in gene expression for Cbfa1 and a 60% decrease for Osteocalcin, with reference to the control. Early marker genes for undifferentiated cells and mesodermal cells were not modified after methotrexate treatment.

CONCLUSIONS

These results show the possibility to integrate specific in vitro tests for teratogenicity in a test strategy for developmental toxicity.

Childhood-onset congenital adrenal hyperplasia: long-term outcome and optimization of therapy

Congenital adrenal hyperplasia is a general term applied to several disorders caused by inherited recessive defects of cortisol synthesis. The most common form is 21-hydroxylase deficiency, accounting for 95% of cases. The classical forms have an incidence of one in 15,000 and the non-classical forms about one in 1,000. The classical or severe phenotype presents in the newborn period or early infancy with virilization and adrenal insufficiency, with or without salt-losing; the non-classical or mild phenotype presents in late childhood or early adulthood with signs of hyperandrogenism. This wide range of clinical expression is explained by genetic variation. Although there is a certain amount of genotype-phenotype correlation, discrepancies have been described. During the last 30 years there has been a substantial improvement in diagnosis and treatment of this disease, and patients with CAH now reach adulthood. Treatment of this condition is intended to reduce excessive corticotropin secretion and replace glucocorticoids and mineralocorticoids as physiologically as possible. Clinical management is often complicated by periods of inadequately treated hyperandrogenism, iatrogenic hypercortisolism, or both. Long-term consequences in adult life may include short stature, obesity, diminished bone mass, gonadal dysfunction with low fertility rates and psychosexual dysfunction in females. New treatment approaches are under investigation, such as the use of anti-androgens, inhibitors of estrogen production and adrenalectomy for severely resistant cases.

Impairment of renal vasodilation with l-arginine is related to more severe disease in untreated hypertensive patients

Data remain insufficient to place the decreased response to L-arginine in hypertensive patients within a consistent pathophysiological sequence. The aim of the present study in patients with essential hypertension was to assess the relationships between the response to L-arginine and a set of relevant clinical and laboratory parameters. In this prospective, interventional study, we administered L-arginine to untreated hypertensive individuals and healthy control subjects and measured the clearance of inulin and of para-aminohippurate and a set of biochemical and clinical variables. L-Arginine infusion revealed major differences between control subjects and 1 subgroup (group B) of hypertensive individuals. Group B hypertensives (n=18) had no increase in inulin clearance and no decrease in renal vascular resistance with L-arginine; however, in another subset of hypertensive patients (group A, n=27), the insulin clearance increased and renal vascular resistance decreased similar to the control group (group C, n=11). The ambulatory blood pressure monitoring in group B showed both an increased mean diastolic pressure and a "nondipper" pattern in the nocturnal regulation of arterial pressure. These findings in group B were accompanied by significant alterations in optic fundus and left ventricle hypertrophy and increased microalbuminuria (all, P<0.05). Furthermore, group B individuals had significantly lower values of HDL cholesterol and a higher baseline atherogenic index, plasma insulin level, and glucose/insulin index. We disclose a previously undescribed relationship between end organ repercussion and decreased renal hemodynamic response to L-arginine. Our results may help to understand the mechanisms that lead to target organ damage in hypertension.

[Increase of tubular secretion of creatinine by L-arginine: mechanism of practical significance in the assessment of renal function based on creatinine clearance]

BACKGROUND

Tubular secretion of creatinine is increased by meat meals. This increment has been attributed to the formation of new creatinine from creatine contained in the cooked meals. However, no studies are available using amino acid infusions containing no creatine, which allow to further investigate the putative causes of increment in tubular creatinine secretion.

METHODS

We performed a prospective, interventional study involving 34 individuals with normal renal function participating in a protocol on arterial hypertension. A continuous infusion of L-arginine (6%, i.v., in four 30 min periods at 50, 100, 200 and 300 ml/h) was administered. Creatinine (CCr) and inulin (CIn) clearances were determined at baseline and during L-arginine infusion. We analyzed the effects of L-arginine on tubular secretion by comparing CCr and CIn and calculated tubular secretion of creatinine (TSCr).

RESULTS

L-arginine infusion induced a significant increase in both CCr and CIn. CCr and CIn were respectively 117.9 +/- 22.7 and 107.5 +/- 23, before and 170.3 +/- 23 and 144.2 +/- 47.8 after the infusion of L-arginine (both p < 0.01). This increase was simultaneous with an increment in TSCr from 1.12 +/- 0.4 to 1.43 +/- 0.6 (p < 0.01). CCr correlated significantly with CIn at baseline and at 60 min of infusion (r = 0.365, p = 0.031 and r = 0.368, p = 0.038, respectively), but not at 120 min (r = 0.130, p = 0.412), a time corresponding to the maximum increase in CIn and TSCr.

CONCLUSIONS

L-arginine induces a substantial increase of CCr, which exceeds that expected from the increase in glomerular filtration rate measured by CIn and corresponds to an increment in TSCr. This phenomenon adds a new interpretation of the effect of amino acids on tubular handling of creatinine and has practical implications in the evaluation of renal function by means of creatinine clearance.