Reversing vemurafenib-resistance in primary melanoma cells by combined romidepsin and type I IFN treatment through blocking of tumorigenic signals and induction of immunogenic effects

BRAF^V600 mutations are the most common oncogenic alterations in melanoma cells, supporting proliferation, invasion, metastasis and immune evasion. In patients, these aberrantly activated cellular pathways are inhibited by BRAFi whose potent antitumor effect and therapeutic potential are dampened by the development of resistance. Here, by using primary melanoma cell lines, generated from lymph node lesions of metastatic patients, we show that the combination of two FDA-approved drugs, the histone deacetylate inhibitor (HDCAi) romidepsin and the immunomodulatory agent IFN-α2b, reduces melanoma proliferation, long-term survival and invasiveness and overcomes acquired resistance to the BRAFi vemurafenib (VEM). Targeted resequencing revealed that each VEM-resistant melanoma cell line and the parental counterpart are characterized by a distinctive and similar genetic fingerprint, shaping the differential and specific antitumor modulation of MAPK/AKT pathways by combined drug treatment. By using RNA-sequencing and functional in vitro assays, we further report that romidepsin-IFN-α2b treatment restores epigenetically silenced immune signals, modulates MITF and AXL expression and induces both apoptosis and necroptosis in sensitive and VEM-resistant primary melanoma cells. Moreover, the immunogenic potential of drug-treated VEM-resistant melanoma cells results significantly enhanced, given the increased phagocytosis rate of these cells by dendritic cells, which in turn exhibit also a selective down-modulation of the immune checkpoint TIM-3. Overall, our results provide evidence that combined epigenetic-immune drugs can overcome VEM resistance of primary melanoma cells by oncogenic and immune pathways reprogramming, and pave the way for rapidly exploiting this combination to improve BRAFi-resistant metastatic melanoma treatment, also via reinforcement of immune checkpoint inhibitor therapy.

Drugs and convalescent plasma therapy for COVID-19: a survey of the interventional clinical studies in Italy after 1 year of pandemic

Background

The 2019 novel coronavirus disease (COVID-19) pandemic has highlighted the importance of health research and fostered clinical research as never before. A huge number of clinical trials for potential COVID-19 interventions have been launched worldwide. Therefore, the effort of monitoring and characterizing the ongoing research portfolio of COVID-19 clinical trials has become crucial in order to fill evidence gaps that can arise, define research priorities and methodological issues, and eventually, formulate valuable recommendations for investigators and sponsors. The main purpose of the present work was to analyze the landscape of COVID-19 clinical research in Italy, by mapping and describing the characteristics of planned clinical trials investigating the role of drugs and convalescent plasma for treatment or prevention of COVID-19 disease.

Methods

During an 11-month period between May 2020 and April 2021, we performed a survey of the Italian COVID-19 clinical trials on therapeutic and prophylactic drugs and convalescent plasma. Clinical trials registered in the Italian Medicines Agency (AIFA) and ClinicalTrials.gov websites were regularly monitored. In the present paper, we report an analysis of study design characteristics and other trial features at 6 April 2021.

Results

Ninety-four clinical trials planned to be carried out in Italy were identified. Almost all of them (91%) had a therapeutic purpose; as for the study design, the majority of them adopted a parallel group (74%) and randomized (76%) design. Few of them were blinded (33%). Eight multiarm studies were identified, and two of them were multinational platform trials. Many therapeutic strategies were investigated, mostly following a drug repositioning therapeutic approach.

Conclusions

Our study describes the characteristics of COVID-19 clinical trials planned to be carried out in Italy over about 1 year of pandemic emergency.

High level quality clinical trials were identified, although some weaknesses in study design and replications of experimental interventions were observed, particularly in the early phase of the pandemic.

Our findings provide a critical view of the clinical research strategies adopted for COVID-19 in Italy during the early phase of the pandemic. Further actions could include monitoring and follow-up of trial results and publications and focus on non-pharmacological research areas.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06474-8.

α-adrenoceptor stimulation attenuates melanoma growth in mice

BACKGROUND AND PURPOSE

Recently, β-adrenoceptor blockade has emerged as a potential strategy to inhibit melanoma growth. However, it remains to be ascertained whether β-adrenoceptor stimulation by circulating catecholamines increases melanoma growth in mice.

EXPERIMENTAL APPROACH

B16F10 melanoma-bearing mice were used to evaluate effects of adrenaline and specific adrenoceptor (AR) ligands on tumor volume. AR expression as well as effects of AR ligands on cell viability, production of mitochondrial reactive oxygen species (mROS) and proliferation activity in B16F10 cells were determined by biochemical analyses.

KEY RESULTS

qPCR analyses revealed that B16F10 cells express both α- (α1B-, α2A- and α2B-AR) and β-ARs (β₂ -AR). We found that treatment with the α- and β-AR agonist adrenaline or with the synthetic catecholamine isoprenaline, that selectively stimulates β-ARs, did not affect melanoma growth. Conversely, adrenaline reduced tumor growth in mice co-treated with propranolol, a β1β2-AR antagonist. Adrenaline had no effect in tumor-bearing β1β2-AR knockout mice, in which β1- and β2-ARs are lacking, but it reduced tumor growth when co-administered with propranolol suggesting that tumor β2-ARs negatively regulate adrenaline antitumor activity. Additionally, we found that α1-AR stimulation with cirazoline yielded a decrease in B16F10 melanoma size. These effects on melanoma growth were paralleled by reduced cell viability and proliferation activity as well as increased mROS production in α1-AR-stimulated B16F10 cells. Decreased viability, proliferation and mitochondrial function in B16F10 cells also occurred after α2-AR stimulation by α2-AR agonist ST-91.

CONCLUSIONS AND IMPLICATIONS

In B16F10 melanoma model, stimulation of α-AR subtypes yields in vivo and in vitro anticancer activity.

Targeting CXCR4 potentiates anti-PD-1 efficacy modifying the tumor microenvironment and inhibiting neoplastic PD-1

Background

Inefficient T-cell access to the tumor microenvironment (TME) is among the causes of tumor immune-resistance. Previous evidence demonstrated that targeting CXCR4 improves anti-PD-1/PD-L1 efficacy reshaping TME. To evaluate the role of newly developed CXCR4 antagonists (PCT/IB2011/000120/ EP2528936B1/US2013/0079292A1) in potentiating anti-PD-1 efficacy two syngeneic murine models, the MC38 colon cancer and the B16 melanoma-human CXCR4-transduced, were employed.

Methods

Mice were subcutaneously injected with MC38 (1 × 10⁶) or B16-hCXCR4 (5 × 10⁵). After two weeks, tumors bearing mice were intraperitoneally (ip) treated with murine anti-PD-1 [RMP1–14] (5 mg/kg, twice week for 2 weeks), Pep R (2 mg/kg, 5 days per week for 2 weeks), or both agents. The TME was evaluated through immunohistochemistry and flow-cytometry. In addition, the effects of the human-anti-PD-1 nivolumab and/or Peptide-R54 (Pep R54), were evaluated on human melanoma PES43 cells and xenografts treated.

Results

The combined treatment, Pep R plus anti-PD-1, reduced the MC38 Relative Tumor Volume (RTV) by 2.67 fold (p = 0.038) while nor anti-PD-1, neither Pep R significantly impacted on tumor growth. Significant higher number of Granzyme B (GZMB) positive cells was detected in MC38 tumors from mice treated with the combined treatment (p = 0.016) while anti-PD-1 determined a modest but significant increase of tumor-infiltrating GZMB positive cells (p = 0.035). Also, a lower number of FoxP3 positive cells was detected (p = 0.022). In the B16-hCXCR4 tumors, two weeks of combined treatment reduced tumor volume by 2.27 fold while nor anti-PD-1 neither Pep R significantly impacted on tumor growth. A significant higher number of GRZB positive cells was observed in B16-hCXCR4 tumors treated with combined treatment (p = 0,0015) as compared to anti-PD-1 (p = 0.028). The combined treatment reduced CXCR4, CXCL12 and PD-L1 expression in MC38 tumors. In addition, flow cytometry on fresh B16-hCXCR4 tumors showed significantly higher Tregs number following anti-PD-1 partially reversed by the combined treatment Pep R and anti-PD-1. Combined treatment determined an increase of CD8/Tregs and CD8/MDSC ratio. To dissect the effect of anti-PD-1 and CXCR4 targeting on PD-1 expressed by human cancer cells, PES43 human melanoma xenograft model was employed. In vitro human anti-PD-1 nivolumab or pembrolizumab (10 μM) reduced PES43 cells growth while nivolumab (10 μM) inhibited pERK1/2, P38 MAPK, pAKT and p4EBP. PES43 xenograft mice were treated with Pep R54, a newly developed Pep R derivative (AcHN-Arg-Ala-[DCys-Arg- Nal(2′)-His-Pen]- COOH), plus nivolumab. After 3 weeks of combined treatment a significant reduction in tumor growth was shown (p = 0.038). PES43 lung disseminated tumor cells (DTC) were detected in fresh lung tissues as melanoma positive MCSP-APC⁺ cells. Although not statistically significant, DTC-PES43 cells were reduced in mice lungs treated with combined treatment while nivolumab or Pep R54 did not affect DTC number.

Conclusion

Combined treatment with the new developed CXCR4 antagonist, Pep R, plus anti-PD-1, reduced tumor-growth in two syngeneic murine models, anti-PD-1 sensitive and resistant, potentiating Granzyme and reducing Foxp3 cells infiltration. In addition, the human specific CXCR4 antagonist, Pep R54, cooperated with nivolumab in inhibiting the growth of the PD-1 expressing human PES43 melanoma xenograft. This evidence sheds light on PD-1 targeting mechanisms and paves the way for CXCR4/PD-1 targeting combination therapy.

The Janus Face of Tumor Microenvironment Targeted by Immunotherapy

The tumor microenvironment (TME) is a complex entity where host immune and non-immune cells establish a dynamic crosstalk with cancer cells. Through cell-cell interactions, which are mediated by key signals, such as the PD-1/PD-L1 axis, as well as the release of soluble mediators, this articulated process defines the nature of TME determining tumor development, prognosis, and response to therapy. Specifically, tumors are characterized by cellular plasticity that allows for the microenvironment to polarize towards inflammation or immunosuppression. Thus, the dynamic crosstalk among cancer, stromal, and immune components crucially favors the dominance of one of the Janus-faced contexture of TME crucial to the outcome of tumor development and therapeutic response. However, mostly, TME is dominated by an immunosuppressive landscape that blocks antitumor immunity and sustain tumor progression. Hence, in most cases, the immunosuppressive components of TME are highly competent in suppressing tumor-specific CD8⁺ T lymphocytes, the effectors of cancer destruction. In this complex context, immunotherapy aims to arm the hidden Janus face of TME disclosing and potentiating antitumor immune signals. Herein, we discuss recent knowledge on the immunosuppressive crosstalk within TME, and share perspectives on how immunotherapeutic approaches may exploit tumor immune signals to generate antitumor immunity.

Inflammatory cytokines associated with cancer growth induce mitochondria and cytoskeleton alterations in cardiomyocytes

Cardiac dysfunction is often observed in patients with cancer also representing a serious problem limiting chemotherapeutic intervention and even patient survival. In view of the recently established role of the immune system in the control of cancer growth, the present work has been undertaken to investigate the effects of a panel of the most important inflammatory cytokines on the integrity and function of mitochondria, as well as of the cytoskeleton, two key elements in the functioning of cardiomyocytes. Either mitochondria features or actomyosin cytoskeleton organization of in vitro‐cultured cardiomyocytes treated with different inflammatory cytokines were analyzed. In addition, to investigate the interplay between tumor growth and cardiac function in an in vivo system, immunocompetent female mice were inoculated with cancer cells and treated with the chemotherapeutic drug doxorubicin at a dosing schedule able to suppress tumor growth without inducing cardiac alterations. Analyses carried out in cardiomyocytes treated with the inflammatory cytokines, such as tumor necrosis factor α (TNF‐α), interferon γ (IFN‐γ), interleukin 6 (IL‐6), IL‐8, and IL‐1β revealed severe phenotypic changes, for example, of contractile cytoskeletal elements, mitochondrial membrane potential, mitochondrial reactive oxygen species production and mitochondria network organization. Accordingly, in immunocompetent mice, the tumor growth was accompanied by increased levels of the inflammatory cytokines TNF‐α, IFN‐γ, IL‐6, and IL‐8, either in serum or in the heart tissue, together with a significant reduction of ventricular systolic function. The alterations of mitochondria and of microfilament system of cardiomyocytes, due to the systemic inflammation associated with cancer growth, could be responsible for remote cardiac injury and impairment of systolic function observed in vivo.

IFN-α potentiates the direct and immune-mediated antitumor effects of epigenetic drugs on both metastatic and stem cells of colorectal cancer

Epigenetic alterations, including dysregulated DNA methylation and histone modifications, govern the progression of colorectal cancer (CRC). Cancer cells exploit epigenetic regulation to control cellular pathways, including apoptotic and metastatic signals. Since aberrations in epigenome can be pharmacologically reversed by DNA methyltransferase and histone deacetylase inhibitors, epigenetics in combination with standard agents are currently envisaged as a new therapeutic frontier in cancer, expected to overcome drug resistance associated with current treatments. In this study, we challenged this idea and demonstrated that the combination of azacitidine and romidepsin with IFN-α owns a high therapeutic potential, targeting the most aggressive cellular components of CRC, such as metastatic cells and cancer stem cells (CSCs), via tight control of key survival and death pathways. Moreover, the antitumor efficacy of this novel pharmacological approach is associated with induction of signals of immunogenic cell death. Of note, a previously undisclosed key role of IFN-α in inducing both antiproliferative and pro-apoptotic effects on CSCs of CRC was also found. Overall, these findings open a new frontier on the suitability of IFN-α in association with epigenetics as a novel and promising therapeutic approach for CRC management.

Tumor acidosis enhances cytotoxic effects and autophagy inhibition by salinomycin on cancer cell lines and cancer stem cells

Sustained autophagy contributes to the metabolic adaptation of cancer cells to hypoxic and acidic microenvironments. Since cells in such environments are resistant to conventional cytotoxic drugs, inhibition of autophagy represents a promising therapeutic strategy in clinical oncology. We previously reported that the efficacy of hydroxychloroquine (HCQ), an autophagy inhibitor under clinical investigation is strongly impaired in acidic tumor environments, due to poor uptake of the drug, a phenomenon widely associated with drug resistance towards many weak bases. In this study we identified salinomycin (SAL) as a potent inhibitor of autophagy and cytotoxic agent effective on several cancer cell lines under conditions of transient and chronic acidosis. Since SAL has been reported to specifically target cancer-stem cells (CSC), we used an established model of breast CSC and CSC derived from breast cancer patients to examine whether this specificity may be associated with autophagy inhibition. We indeed found that CSC-like cells are more sensitive to autophagy inhibition compared to cells not expressing CSC markers. We also report that the ability of SAL to inhibit mammosphere formation from CSC-like cells was dramatically enhanced in acidic conditions. We propose that the development and use of clinically suitable SAL derivatives may result in improved autophagy inhibition in cancer cells and CSC in the acidic tumor microenvironment and lead to clinical benefits.

Targeting CXCR4 reverts the suppressive activity of T-regulatory cells in renal cancer

With the intent to identify biomarkers in renal cell carcinoma (RCC) the functional status of T-regulatory cells (Tregs) was investigated in primary RCC. Tregs were isolated from tumoral-(TT), peritumoral tissue-(PT) and peripheral blood-(PB) of 42 primary RCC patients and function evaluated through effector T cells (Teff) proliferation, cytokines release and demethylation of Treg Specific Region (TSDR). The highest value of Tregs was detected in TT with the uppermost amount of effector-Tregs-(CD4⁺CD25^hiFOXP3^hiCD45RA^-). PB-RCC Tregs efficiently suppress Teff proliferation compared to healthy donor (HD)-Tregs and, at the intrapatient evaluation, TT-derived Tregs were the most suppressive. Higher demethylation TSDR was detected in TT- and PB-RCC Tregs vs HD-Tregs (P <0,001). CXCR4 is highly expressed on Tregs, thus we wished to modulate Tregs function through CXCR4 inhibition. CXCR4 antagonism, elicited by a new peptidic antagonist, Peptide-R29, efficiently reversed Tregs suppression of Teff proliferation. Thus Tregs functional evaluation precisely reflects Tregs status and may be a reliable biomarker of tumoral immune response. In addition, treatment with CXCR4 antagonist, impairing Tregs function, could improve the anticancer immune response, in combination with conventional therapy and/or immunotherapy such as checkpoints inhibitors.

Phosphatidylcholine-specific phospholipase C inhibition reduces HER2-overexpression, cell proliferation and in vivo tumor growth in a highly tumorigenic ovarian cancer model

Antagonizing the oncogenic effects of human epidermal growth factor receptor 2 (HER2) with current anti-HER2 agents has not yet yielded major progress in the treatment of advanced HER2-positive epithelial ovarian cancer (EOC). Using preclinical models to explore alternative molecular mechanisms affecting HER2 overexpression and oncogenicity may lead to new strategies for EOC patient treatment. We previously reported that phosphatidylcholine-specific phospholipase C (PC-PLC) exerts a pivotal role in regulating HER2 overexpression in breast cancer cells. The present study, conducted on two human HER2-overexpressing EOC cell lines - SKOV3 and its in vivo-passaged SKOV3.ip cell variant characterized by enhanced in vivo tumorigenicity - and on SKOV3.ip xenografts implanted in SCID mice, showed: a) about 2-fold higher PC-PLC and HER2 protein expression levels in SKOV3.ip compared to SKOV3 cells; b) physical association of PC-PLC with HER2 in non-raft domains; c) HER2 internalization and ca. 50% reduction of HER2 mRNA and protein expression levels in SKOV3.ip cells exposed to the PC-PLC inhibitor tricyclodecan-9-yl-potassium xanthate (D609); d) differential effects of D609 and trastuzumab on HER2 protein expression and cell proliferation; e) decreased in vivo tumor growth in SKOV3.ip xenografts during in vivo treatment with D609; f) potential use of in vivo magnetic resonance spectroscopy (MRS) and imaging (MRI) parameters as biomarkers of EOC response to PC-PLC inhibition. Overall, these findings support the view that PC-PLC inhibition may represent an effective means to target the tumorigenic effects of HER2 overexpression in EOC and that in vivo MR approaches can efficiently monitor its effects.

Antitumor Effects of Epidrug/IFNα Combination Driven by Modulated Gene Signatures in Both Colorectal Cancer and Dendritic Cells

Colorectal cancer results from the progressive accumulation of genetic and epigenetic alterations. IFN signaling defects play an important role in the carcinogenesis process, in which the inability of IFN transcription regulatory factors (IRF) to access regulatory sequences in IFN-stimulated genes (ISG) in tumors and in immune cells may be pivotal. We reported that low-dose combination of two FDA-approved epidrugs, azacytidine (A) and romidepsin (R), with IFNα2 (ARI) hampers the aggressiveness of both colorectal cancer metastatic and stem cells in vivo and triggers immunogenic cell death signals that stimulate dendritic cell (DC) function. Here, we investigated the molecular signals induced by ARI treatment and found that this drug combination increased the accessibility to regulatory sequences of ISGs and IRFs that were epigenetically silenced in both colorectal cancer cells and DCs. Likewise, specific ARI-induced histone methylation and acetylation changes marked epigenetically affected ISG promoters in both metastatic cancer cells and DCs. Analysis by ChIP-seq confirmed such ARI-induced epigenetically regulated IFN signature. The activation of this signal endowed DCs with a marked migratory capability. Our results establish a direct correlation between reexpression of silenced ISGs by epigenetic control and ARI anticancer activity and provide new knowledge for the development of innovative combined therapeutic strategies for colorectal cancer. Cancer Immunol Res; 5(7); 604-16. ©2017 AACR.

The gender perspective in cancer research and therapy: novel insights and on-going hypotheses

Cancer represents a leading cause of death whose incidence is steadily increasing worldwide due to the population aging. The Global Health Observatory of the World Health Organization reported that approximately 13% of all deaths are caused by cancer. In the 2012 the estimated total number of cancer deaths was 1.75 million, 56% in men and 44% in women. Gender is recognized to play a role in cancer incidence, progression and response to therapy. Besides anatomical and hormonal disparities, genetic differences should be considered when assessing the effects of gender on cancer. Accumulating evidence also support the existence of sex-driven differences in immune responses. Until today clinical trials and research in animal models have been gender unbalanced. In consideration of the differences between sexes observed in cancer, sex should represent an important stratification factor to be included in all randomized clinical trials for a better understanding of biological differences between men and women, which may yield improved targeted therapies.

Biphasic effects of propranolol on tumour growth in B16F10 melanoma-bearing mice

BACKGROUND AND PURPOSE

Propranolol is a vasoactive drug that shows antiangiogenic and antitumour activities in melanoma. However, it is unknown whether these activities are dose-dependent and whether there is a relationship between systemic vascular effects of propranolol and anti-melanoma activity.

EXPERIMENTAL APPROACH

Effects of increasing doses of propranolol (10, 20, 30 and 40 mg·kg^-1 ·day^-1 ) on tumour growth were studied in B16F10 melanoma-bearing mice. Histological and biochemical analyses were used to assess propranolol effects on angiogenesis and cancer cell proliferation. Systemic vascular resistance (SVR) was evaluated by measuring cardiac output and arterial BP.

KEY RESULTS

In vitro analyses revealed that B16F10 cells expressed β-adrenoceptors, but neither isoprenaline, a β-adrenoceptor agonist, nor the β-blocker propranolol affected cancer cell proliferation. In vivo studies showed that the antitumour efficacy of propranolol follows a U-shaped biphasic dose-response curve. Low doses (10 and 20 mg·kg^-1 ·day^-1 ) significantly inhibit tumour growth, whereas higher doses are progressively less effective. We also found that high-dose propranolol stimulates tumour arteriogenesis whereas no effect on angiogenesis was observed at any dose. Based on these data and considering that propranolol is a vasoactive drug, we hypothesized that it causes systemic vasoconstriction or vasodilation depending on the dose and thus alters tumour perfusion and growth. Consistent with this hypothesis, we found that propranolol has a biphasic effect on SVR with low and high doses producing vasoconstriction and vasodilation respectively.

CONCLUSIONS AND IMPLICATIONS

Propranolol inhibits melanoma growth in a U-shaped biphasic manner. A direct relationship exists between SVR and anti-melanoma activity.

New derivatives of the antimalarial drug Pyrimethamine in the control of melanoma tumor growth: an in vitro and in vivo study

Background

The antimalarial drug Pyrimethamine has been suggested to exert an antitumor activity by inducing apoptotic cell death in cancer cells, including metastatic melanoma cells. However, the dose of Pyrimethamine to be considered as an anticancer agent appears to be significantly higher than the maximum dose used as an antiprotozoal drug.

Methods

Hence, a series of Pyrimethamine analogs has been synthesized and screened for their apoptosis induction in two cultured metastatic melanoma cell lines. One of these analogs, the Methylbenzoprim, was further analyzed to evaluate cell-cycle and the mechanisms of cell death. The effects of Methylbenzoprim were also analyzed in a severe combined immunodeficiency (SCID)-mouse xenotransplantation model.

Results

Low dose of Methylbenzoprim was capable of inducing cytotoxic activity and a potent growth-inhibitory effect by arresting cell cycle in S-phase in melanoma cells. Methylbenzoprim was also detected as powerful antineoplastic agents in SCID-mouse although used at very low dose and as a single agent.

Conclusions

Our screening approach led to the identification of a “low cost” newly synthesized drug (methylbenzoprim), which is able to act as an antineoplastic agent in vitro and in vivo, inhibiting melanoma tumor growth at very low concentrations.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0409-9) contains supplementary material, which is available to authorized users.

CXCR4-antagonist Peptide R-liposomes for combined therapy against lung metastasis

The chemokine CXCL12 activates CXCR4, initiating multiple pathways that control immune cell trafficking, angiogenesis and embryogenesis; CXCR4 is also overexpressed in multiple tumors affecting metastatic dissemination. While there has been great enthusiasm for exploiting the CXCR4-CXCL12 axis as a target in cancer therapy, to date the promise has yet to be fulfilled. A new class of CXCR4-antagonist cyclic peptides was recently developed and the compound named Peptide R was identified as the most active. With the intent to improve the efficacy and biodistribution of Peptide R, stealth liposomes decorated with Peptide R were developed (PL-Peptide R). In vitro PL-Peptide R efficiently inhibited CXCR4-dependent migration and in vivo it significantly reduced lung metastases and increased overall survival in B16-CXCR4 injected C57BL/6 mice. To evaluate if PL-Peptide R could also be a drug delivery system for CXCR4 expressing tumors, the PL-Peptide R was loaded with doxorubicin (DOX) (PL-Peptide R-DOX). PL-Peptide R-DOX efficiently delivered DOX to CXCR4 expressing cell lines with a consequent decrease in the DOX IC50 efficient dose. In vivo, B16-CXCR4 injected C57BL/6 mice treated with PL-Peptide R-DOX developed fewer lung metastases compared to PL-DOX treated mice. This work provides the proof-of-concept to prevent metastasis by using combined nanomedicine.

Abstract 1656: CXCR4 antagonist-expressing liposomes reduce lung metastases and deliver drugs to CXCR4 expressing cells: a new drug-targeting device

Introduction. CXCR4 is overexpressed in multiple tumors regulating metastatic dissemination. A new class of cyclic peptides antagonist for CXCR4 receptors was recently developed1. To improve peptide efficacy and increase its delivery delivery to target cancer cells the most active antagonist, Pep R, was coupled to PEGylated liposomes (PL).

Experimental Procedures. PL conjugated to the liposomes (Lip-PepR) were prepared starting by athiolated derivative of antiCXCR4 peptides coupled to the pre-formed PL. Doxorubicin (DOX) was then encapsulated by remote loading method. Lip-PepR was evaluated through migration assay in A498 human renal cancer cell line in vitro and in an experimental animal model of pulmonary metastasis development in vivo (C57/BL mice injected with B16-CXCR4 cells and treated with 0.1 mg/kg Lipo-PepR and lipo-unconjucated i.v. twice a week for two weeks). DOX-encapsulating Lipo-PepR was evaluated in CXCR4 positive cells A498 and HT29 (human renal and colon cancer cell lines, respectivally) versus negative CXCR4 expressing cells FB-1(human anaplastic thyroid cell line), as mean cellular fluorescence. Finally, the cytotoxic effect of the lipo-DOX-PepR was examined, in A498, and HT29 cells.

Results. To evaluate the antagonistic CXCR4 function of Lipo-PepR, migration assays were conducted in A498, CXCR4 expressing cells. A498 cells were treated with the PepR or with liposome preparation (Lipo-PepR) and induced to migrate toward the CXCR4 ligand CXCL12. PepR alone inhibited cell migration such as the CXCR4 antagonist, AMD3100 while the functionalized peptide, Lipo-PepR (10µM) more efficiently inhibited migration CXCL12-induced compared. To validate the Lipo-PepR efficacy in vivo, metastases development assays were conducted. C57/BL mice were injected with murine B16-hCXCR4 melanoma cells and treated twice a week iv with Lipo-PepR versus Peptide R alone. A significant reduction in lung metastases was detected in mice treated with Lipo-Pep R even with lower dose of the Lipo-PepR (0.1mg/kg) compared to the usually used (2mg/kg). Moreover, to allow a target selective drug delivery, Lipo-PepR liposomes were loaded with doxorubicin (DOX). A CXCR4 dependent higher DOX accumulation was registered in CXCR4 positive cells, A498 and HT29 resulting in a specific higher cytotoxicity.

Conclusions. Liposomes conjugated- rationally designed CXCR4 antagonist were more efficient in inhibiting CXCR4 in vitro and in vivo. Moreover Lip-PepR loaded with a chemotherapeutic drug, such as DOX, demonstrated an enhanced drug accumulation into CXCR4 overexpressing cells.

1. Portella L et al. PLoS One. 2013 Sep 13;8(9):e74548

Citation Format: Caterina Ierano, Sara Lusa, Crescenzo D'Alterio, Giuseppina Salzano, Maria Napolitano, Maria Buoncervello, Massimo Spada, Daniele Macchia, Antonio Barbieri, Antonio Luciano, Lucia Gabriele, Giuseppe De Rosa, Stefania Scala. CXCR4 antagonist-expressing liposomes reduce lung metastases and deliver drugs to CXCR4 expressing cells: a new drug-targeting device. [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 1656. doi:10.1158/1538-7445.AM2014-1656

Acidic extracellular pH neutralizes the autophagy-inhibiting activity of chloroquine: implications for cancer therapies

Acidic pH is an important feature of tumor microenvironment and a major determinant of tumor progression. We reported that cancer cells upregulate autophagy as a survival mechanism to acidic stress. Inhibition of autophagy by administration of chloroquine (CQ) in combination anticancer therapies is currently evaluated in clinical trials. We observed in 3 different human cancer cell lines cultured at acidic pH that autophagic flux is not blocked by CQ. This was consistent with a complete resistance to CQ toxicity in cells cultured in acidic conditions. Conversely, the autophagy-inhibiting activity of Lys-01, a novel CQ derivative, was still detectable at low pH. The lack of CQ activity was likely dependent on a dramatically reduced cellular uptake at acidic pH. Using cell lines stably adapted to chronic acidosis we could confirm that CQ lack of activity was merely caused by acidic pH. Moreover, unlike CQ, Lys-01 was able to kill low pH-adapted cell lines, although higher concentrations were required as compared with cells cultured at normal pH conditions. Notably, buffering medium pH in low pH-adapted cell lines reverted CQ resistance. In vivo analysis of tumors treated with CQ showed that accumulation of strong LC3 signals was observed only in normoxic areas but not in hypoxic/acidic regions. Our observations suggest that targeting autophagy in the tumor environment by CQ may be limited to well-perfused regions but not achieved in acidic regions, predicting possible limitations in efficacy of CQ in antitumor therapies.