The relevance of testing the efficacy of anti-angiogenesis treatments on cells derived from primary tumors: a new method for the personalized treatment of renal cell carcinoma

Kinomic profiling to predict sunitinib response of patients with metastasized clear cell Renal Cell Carcinoma

INTRODUCTION

Treatment with Sunitinib, a potent multitargeted receptor tyrosine kinase inhibitor (TKI) has increased the progression-free survival (PFS) and overall-survival (OS) of patients with metastasized renal cell carcinoma (mRCC). With modest OS improvement and variable response and toxicity predictive and/or prognostic biomarkers are needed to personalize patient management: Prediction of individual TKI therapy response and resistance will increase successful treatment outcome while reducing unnecessary drug use and expense. The aim of this study was to investigate whether kinase activity analysis can predict sunitinib response and/or toxicity using tissue samples obtained from primary clear cell RCC (ccRCC) from a cohort of clinically annotated patients with mRCC receiving sunitinib as first-line treatment.

MATERIALS AND METHODS

EuroTARGET partners collected ccRCC and matched normal kidney tissue samples immediately after surgery, snap-frozen and stored at -80°C until use. Phosphotyrosine-activity profiling was performed using PamChip® peptide microarrays (144 peptides derived from known phosphorylation sites in Protein Tyrosine Kinase substrates) of lysed tissue samples (5 µg protein input) of 163 mRCC patients. Evolve software Was used to analyze kinome profiles and Bionavigator was used for unsupervised and supervised clustering. The kinexus kinase predictor (www.phosphonet.ca) was used to analyze the peptide lists within the clusters.

RESULTS

Kinome data was available from 94 patients who received sunitinib as 1st-line treatment and had complete follow-up of their clinical data (PFS, OS and toxicity) for at least 6 months. Matched normal tissue was available from 14 mRCC patients. Supervised clustering of basal kinome activity could correctly classify mRCC patients with PFS >9 months versus PFS<9 months with an accuracy of 61 %. Unsupervised hierarchical clustering revealed 3 major clusters related to immune signaling, VEGF pathway, and immune signaling/cell adhesion. Basal kinase activity levels of patients with short PFS were substantially higher compared to patients who experienced extended PFS.

DISCUSSION/CONCLUSION

Based on kinase levels ccRCC tumors can be subdivided into 3 clusters which may reflect the aggressiveness of these tumors. The accuracy of response prediction of 61 % based on basal kinase levels is too low to justify implementation. STK assays may help to predict sunitinib toxicity and guide clinical management. Additionally, it is possible that mRCC patients with an immune kinase signature are better checkpoint inhibitor candidates, but this needs to be studied.

Targeting of the ELR+CXCL/CXCR1/2 Pathway Is a Relevant Strategy for the Treatment of Paediatric Medulloblastomas

Medulloblastoma (MB) is the most common and aggressive paediatric brain tumour. Although the cure rate can be as high as 70%, current treatments (surgery, radio- and chemotherapy) excessively affect the patients' quality of life. Relapses cannot be controlled by conventional or targeted treatments and are usually fatal. The strong heterogeneity of the disease (four subgroups and several subtypes) is related to innate or acquired resistance to reference treatments. Therefore, more efficient and less-toxic therapies are needed. Here, we demonstrated the efficacy of a novel inhibitor (C29) of CXCR1/2 receptors for ELR+CXCL cytokines for the treatment of childhood MB. The correlation between ELR+CXCL/CXCR1/2 expression and patient survival was determined using the R2: Genomics Analysis and Visualization platform. In vitro efficacy of C29 was evaluated by its ability to inhibit proliferation, migration, invasion, and pseudo-vessel formation of MB cell lines sensitive or resistant to radiotherapy. The growth of experimental MB obtained by MB spheroids on organotypic mouse cerebellar slices was also assayed. ELR+CXCL/CXCR1/2 levels correlated with shorter survival. C29 inhibited proliferation, clone formation, CXCL8/CXCR1/2-dependent migration, invasion, and pseudo-vessel formation by sensitive and radioresistant MB cells. C29 reduced experimental growth of MB in the ex vivo organotypic mouse model and crossed the blood-brain barrier. Targeting CXCR1/2 represents a promising therapeutic strategy for the treatment of paediatric MB in first-line treatment or after relapse following conventional therapy.

RBM10-TFE3 fusions: A FISH-concealed anomaly in adult renal cell carcinomas displaying a variety of morphological and genomic features: Comprehensive study of six novel cases

The accurate diagnosis of Xp11-translocation renal cell carcinoma (RCC) in adults is challenging. TFE3 (located on chromosome X) fuses with a partner gene generally located on another chromosome. In rare cases TFE3 may fuse with a neighboring gene: RBM10. Because TFE3 false-positive immunostaining is a common pitfall in many laboratories, demonstration of the chromosomal rearrangement is required in order to ascertain the diagnosis. Fluorescence in situ hybridization (FISH)-that has been considered as the gold standard method-reaches its limits for detecting small Xp11 paracentric inversions. We performed a comprehensive clinical, histological and genomic study of six novel cases of RCC with RBM10-TFE3 fusion. Using FISH, TFE3 rearrangement was equivocal in one case and negative in others. RBM10-TFE3 fusion was discovered using targeted RNA sequencing (RNASeq). As all the previously reported cases (mean age: 50), the six patients were adults (mean age: 42), suggesting an epidemiologic difference between RBM10-TFE3 RCC and tumors harboring some other partner genes, such as ASPSCR1 that rather occur in children. Array-comparative genomic hybridization showed several alterations, notably a gain of 17q in four cases with papillary features and loss of 3p in one case with clear cells. Our study demonstrates that, though rare among adult cases of RCC, RBM10-TFE3 fusion is not exceptional and warrants appropriate molecular detection. Notably, it would be worthy to systemically investigate by RNASeq challenging RCC with type-2 papillary features and 17q gain.

Anti-Vascular Endothelial Growth Factor C Antibodies Efficiently Inhibit the Growth of Experimental Clear Cell Renal Cell Carcinomas

Despite improvement during the last ten years in the longevity of patients with metastatic clear cell renal cell carcinoma (mccRCC) the disease remains incurable. Hence, new therapeutic strategies are urgently needed. Relapse following anti-angiogenic treatment depends on the over-expression of vascular endothelial growth factor C (VEGFC), one of the main drivers of lymphangiogenesis. Therefore, we developed specific mouse monoclonal antibodies and evaluated their therapeutic efficacy in vitro and in vivo. Immunization of mice with the domain of VEGFC that stimulates the VEGF receptor 3 (VEGFR3) led to the selection of one hybridoma producing specific anti-VEGFC monoclonal antibodies. The selected 1E9 antibodies were sequenced, and the corresponding variable light and heavy chains were subcloned into expression vectors in frame with sequences encoding the human IgG1 constant heavy and light chains. CHO cells were stably transfected and cloned to produce chimeric antibodies. These antibodies inhibited the activation of VEGFR3 signaling, and therefore the proliferation and migration of VEGFC-stimulated endothelial cells. Moreover, they inhibited the proliferation of VEGFC-expressing renal cancer cells through NRP2 signaling. 1E9 antibodies inhibited the growth of experimental RCC, and their therapeutic efficacy was enhanced by the anti-VEGF antibody bevacizumab. Hence, our results suggest that targeting VEGFC could have a relevant therapeutic impact on mccRCC that relapse following anti-angiogenic treatment.

Plk1, upregulated by HIF-2, mediates metastasis and drug resistance of clear cell renal cell carcinoma

Polo-like kinase 1 (Plk1) expression is inversely correlated with survival advantages in many cancers. However, molecular mechanisms that underlie Plk1 expression are poorly understood. Here, we uncover a hypoxia-regulated mechanism of Plk1-mediated cancer metastasis and drug resistance. We demonstrated that a HIF-2-dependent regulatory pathway drives Plk1 expression in clear cell renal cell carcinoma (ccRCC). Mechanistically, HIF-2 transcriptionally targets the hypoxia response element of the Plk1 promoter. In ccRCC patients, high expression of Plk1 was correlated to poor disease-free survival and overall survival. Loss-of-function of Plk1 in vivo markedly attenuated ccRCC growth and metastasis. High Plk1 expression conferred a resistant phenotype of ccRCC to targeted therapeutics such as sunitinib, in vitro, in vivo, and in metastatic ccRCC patients. Importantly, high Plk1 expression was defined in a subpopulation of ccRCC patients that are refractory to current therapies. Hence, we propose a therapeutic paradigm for improving outcomes of ccRCC patients.

Neuropilin 1 and Neuropilin 2 gene invalidation or pharmacological inhibition reveals their relevance for the treatment of metastatic renal cell carcinoma

Background

Despite the improvement of relapse-free survival mediated by anti-angiogenic drugs like sunitinib (Sutent®), or by combinations of anti-angiogenic drugs with immunotherapy, metastatic clear cell Renal Cell Carcinoma (mccRCC) remain incurable. Hence, new relevant treatments are urgently needed. The VEGFs coreceptors, Neuropilins 1, 2 (NRP1, 2) are expressed on several tumor cells including ccRCC. We analyzed the role of the VEGFs/NRPs signaling in ccRCC aggressiveness and evaluated the relevance to target this pathway.

Methods

We correlated the NRP1, 2 levels to patients’ survival using online available data base. Human and mouse ccRCC cells were knocked-out for the NRP1 and NRP2 genes by a CRISPR/Cas9 method. The number of metabolically active cells was evaluated by XTT assays. Migration ability was determined by wound closure experiments and invasion ability by using Boyden chamber coated with collagen. Production of VEGFA and VEGFC was evaluated by ELISA. Experimental ccRCC were generated in immuno-competent/deficient mice. The effects of a competitive inhibitor of NRP1, 2, NRPa-308, was tested in vitro and in vivo with the above-mentioned tests and on experimental ccRCC. NRPa-308 docking was performed on both NRPs.

Results

Knock-out of the NRP1 and NRP2 genes inhibited cell metabolism and migration and stimulated the expression of VEGFA or VEGFC, respectively. NRPa-308 presented a higher affinity for NRP2 than for NRP1. It decreased cell metabolism and migration/invasion more efficiently than sunitinib and the commercially available NRP inhibitor EG00229. NRPa-308 presented a robust inhibition of experimental ccRCC growth in immunocompetent and immunodeficient mice. Such inhibition was associated with decreased expression of several pro-tumoral factors. Analysis of the TCGA database showed that the NRP2 pathway, more than the NRP1 pathway correlates with tumor aggressiveness only in metastatic patients.

Conclusions

Our study strongly suggests that inhibiting NRPs is a relevant treatment for mccRCC patients in therapeutic impasses and NRPa-308 represents a relevant hit.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01832-x.

Targeting the ERβ/Angiopoietin-2/Tie-2 signaling-mediated angiogenesis with the FDA-approved anti-estrogen Faslodex to increase the Sunitinib sensitivity in RCC

Sunitinib has been used as the main therapy to treat the metastatic clear cell renal cell carcinoma (ccRCC) as it could function via suppressing the tumor growth and angiogenesis. Yet most ccRCC tumors may still regrow due to the development of sunitinib-resistance, and detailed mechanisms remain to be further investigated. The angiopoietin family includes angiopoietin-1 and angiopoietin-2 (ANGPT-1 and -2). It was reported that estradiol regulates expression of ANGPT-1, but not ANGPT-2, through estrogen receptor α (ERα) in an experimental stroke model. To date, there is no finding to link the E2/ER signal on regulating ANGPT-2. Our study is the first to explore (i) how estrogen receptor β (ERβ) can up-regulate ANGPT-2 in RCC cells, and (ii) how ERβ-increased ANGPT-2 can promote the HUVEC tube formation and reduce sunitinib sensitivity. Mechanistic studies revealed that ERβ could function via transcriptional regulation of the cytokine ANGPT-2 in the ccRCC cells. We found the up-regulated ANGPT-2 of RCC cells could then increase the Tie-2 phosphorylation to promote the angiogenesis and increase sunitinib treatment resistance of endothelial cells. In addition to the endothelial cell tube formation and aortic ring assay, preclinical studies with a mouse RCC model also confirmed the finding. Targeting this newly identified ERβ/ANGPT-2/Tie-2 signaling pathway with the FDA-approved anti-estrogen, Faslodex, may help in the development of a novel combined therapy with sunitinib to better suppress the ccRCC progression.

The combination of bevacizumab/Avastin and erlotinib/Tarceva is relevant for the treatment of metastatic renal cell carcinoma: the role of a synonymous mutation of the EGFR receptor

Metastatic clear cell renal cell carcinomas (mRCC) over-express the vascular endothelial growth factor (VEGF). Hence, the anti-VEGF antibody bevacizumab/Avastin (BVZ) combined with interferon alpha (IFN) was approved for the treatment of mRCC. However, approval was lost in July 2016 due to the absence of sustained efficacy. We previously showed that BVZ accelerates tumor growth in experimental models of mRCC in mice, results in part explained by down-regulation of the phospho tyrosine phosphatase receptor kappa (PTPRκ) in tumor cells. The epidermal growth factor receptor (EGFR) is a direct target of PTPRκ. Its down-regulation leads to constitutive activation of EGFR, an observation which prompted us to test the effect of the EGFR inhibitor erlotinib/Tarceva (ERLO) in addition to BVZ/IFN. The influence of the long non-coding RNA, EGFR-AS1, on ERLO efficacy was also addressed.

Methods: The effect of BVZ/IFN/ERLO was tested on the growth of experimental tumors in nude mice. The presence of germline mutation in the EGFR was evaluated on cell lines and primary RCC cells. In vitro translation and transfections of expression vectors coding the wild-type or the EGFR mutated gene in HEK-293 cells were used to test the role of EGFR mutation of the ERLO efficacy. Correlation between EGFR/EGFR-AS1 expression and survival was analyzed with an online available data base (TCGA).

Results: Tumor growth was strongly reduced by the triple combination BVZ/IFN/ERLO and linked to reduced levels of pro-angiogenic/pro-inflammatory cytokines of the ELR+CXCL family and to subsequent inhibition of vascularization, a decreased number of lymphatic vessels and polarization of macrophages towards the M1 phenotype. Cells isolated from surgical resection of human tumors presented a range of sensitivity to ERLO depending on the presence of a newly detected mutation in the EGFR and to the presence of EGFR-AS1.

Conclusions: Our results point-out that the BVZ/IFN/ERLO combination deserves testing for the treatment of mRCC that have a specific mutation in the EGFR.

New CXCR1/CXCR2 inhibitors represent an effective treatment for kidney or head and neck cancers sensitive or refractory to reference treatments

Clear cell Renal Cell (RCC) and Head and Neck Squamous Cell Carcinomas (HNSCC) are characterized by a pro-angiogenic/pro-inflammatory context. Despite conventional or targeted therapies, metastatic RCC and HNSCC remain incurable. Alternative treatments to reference therapies (sunitinib, a multi tyrosine kinase inhibitor for RCC or cisplatin for HNSCC) are urgently needed on relapse. Here, we described the relevance of targeting the ELR+CXCL cytokines receptors, CXCR1/2, for the treatment of these two cancer types. Methods: The relevance to patient treatment was evaluated by correlating the ELR⁺CXCL/CXCR1/2 levels to survival using online available data. We report herein the synthesis of new pharmacological inhibitors of CXCR1/2 with anti-proliferation/survival activity. The latter was evaluated with the XTT assay with leukemic, breast, RCC and HNSCC cell lines. Their relevance as an alternative treatment was tested on sunitinib- and cisplatin- resistant cells. The most efficient compound was then tested in a mouse model of RCC and HNSCC. Results: RCC and HNSCC expressed the highest amounts of CXCR1/2 of all cancers. High levels of ELR⁺CXCL cytokines (CXCL1, 2, 3, 5, 6, 7, 8) correlated to shorter survival. Among the 33 synthesized and tested molecules, compound C29 reduced ELR⁺CXCL/CXCR1/2-dependent proliferation and migration of endothelial cells. C29 exerted an anti-proliferation/survival activity on a panel of cancer cells including naive and resistant RCC and HNSCC cells. C29 reduced the growth of experimental RCC and HNSCC tumors by decreasing tumor cell proliferation, angiogenesis and ELR⁺/CXCL-mediated inflammation. Conclusion: Our study highlights the relevance of new CXCR1/2 inhibitors for the treatment of RCC or HNSCC as first-line treatment or at relapse on reference therapies.

Pharmacodynamic Monitoring of mTOR Inhibitors

Pharmacodynamic (PD) monitoring may complement routine pharmacokinetic monitoring of mTOR inhibitors (mTORis) in an attempt to better guide individualized sirolimus (SRL) or everolimus (EVR) treatment after organ transplantation. This review focuses on current knowledge about PD biomarkers for personalized mTORi therapies. Different strategies have already been used in the evaluation of the pharmacodynamics of SRL and EVR as a proxy for their effects on the immune response after transplantation. These include measuring p70S6K (70 kDa ribosomal protein S6 kinase) activity, p70S6K phosphorylation (P-p70S6K), or P-S6 protein expression. Compared with Western blot and ELISA, phosphoflow cytometry can detect phosphorylated proteins and differentiate activation-induced changes of signaling molecules inside the cell from unstimulated populations of identical cells in the same sample. Alternatively, in patients receiving a combined therapy, the other PD approach is to consider biomarkers such as NFAT residual expression for calcineurin inhibitors or to evaluate nonspecific effects of the drugs such as lymphocyte proliferation, interleukin synthesis, specific peripheral blood T regulatory subsets, or lymphocyte surface antigens, which have the advantage to reflect the overall immunosuppressive status achieved. Although limited, the available data on mTOR pathway biomarkers seem promising. Before clinical implementation, the analytical methodologies must be standardized and cross-validated, and the selected biomarkers will have to demonstrate their clinical utility for SRL or EVR dose individualization in multicenter clinical trials.

Chrysin inhibit human melanoma A375.S2 cell migration and invasion via affecting MAPK signaling and NF-κB signaling pathway in vitro

Numerous evidences have shown that chrysin induced cytotoxic effects via induced cell cycle arrest and induction of cell apoptosis in human cancer cell lines, however, no information showed that chrysin inhibited skin cancer cell migration and invasion. In this study, we investigated anti-metastasis mechanisms of chrysin in human melanoma cancer A375.S2 cells in vitro. Under sub-lethal concentrations of chrysin (0, 5, 10, and 15 μM) which inhibits cell mobility, migration and invasion of A375.S2 cells that were assayed by wound healing and Transwell filter. That chrysin inhibited MMP-2 activity in A375.S2 cells was investigated by gelatin zymography assay. Western blotting was used to examine protein expression and results indicated that chrysin inhibited the expression of GRB2, SOS-1, PKC, p-AKT (Thr308), NF-κBp65, and NF-κBp50 at 24 and 48 hours treatment, but only at 10-15 μM of chrysin decreased Ras, PI3K, p-c-Jun, and Snail only at 48 hours treatment and only decrease p-AKT(Ser473) at 24 hours treatment. Furthermore, chrysin (5-15 μM) decreased the expression of uPA, N-cadherin and MMP-1 at 24 and 48 hours treatment but only decreased MMP-2 and VEGF at 48 hours treatment at 10-15 μM and 5-15 μM of chrysin, respectively, however, increased E-cadherin at 5-15 μM treatment. Results of confocal laser microscopy systems indicated that chrysin inhibited expression of NF-κBp65 in A375.S2 cells. Based on these observations, we suggest that chrysin can be used in anti-metastasis of human melanoma cells in the future.

Soluble CD146 is a predictive marker of pejorative evolution and of sunitinib efficacy in clear cell renal cell carcinoma

The objective of the study was to use CD146 mRNA to predict the evolution of patients with non-metastatic clear cell renal cell carcinoma (M0 ccRCC) towards metastatic disease, and to use soluble CD146 (sCD146) to anticipate relapses on reference treatments by sunitinib or bevacizumab in patients with metastatic ccRCC (M1).

Methods: A retrospective cohort of M0 patients was used to determine the prognostic role of intra-tumor CD146 mRNA. Prospective multi-center trials were used to define plasmatic sCD146 as a predictive marker of sunitinib or bevacizumab efficacy for M1 patients.

Results: High tumor levels of CD146 mRNA were linked to shorter disease-free survival (DFS) and overall survival (OS). ccRCC patients from prospective cohorts with plasmatic sCD146 variation <120% following the first cycle of sunitinib treatment had a longer progression-free survival (PFS) and OS. The plasmatic sCD146 variation did not correlate with PFS or OS for the bevacizumab-based treatment. In vitro, resistant cells to sunitinib expressed high levels of CD146 mRNA and protein in comparison to sensitive cells. Moreover, recombinant CD146 protected cells from the sunitinib-dependent decrease of cell viability.

Conclusion: CD146/sCD146 produced by tumor cells is a relevant biological marker of ccRCC aggressiveness and relapse on sunitinib treatment.

Targeting the pro-angiogenic forms of VEGF or inhibiting their expression as anti-cancer strategies

Tumor growth relies on oxygen and blood supply depending on neo-vascularization. This process is mediated by the Vascular Endothelial Growth Factor (VEGF) in many tumors. This paradigm has led to the development of specific therapeutic approaches targeting VEGF or its receptors. Despite their promising effects, these strategies have not improved overall survival of patients suffering from different cancers compared to standard therapies. We hypothesized that the existence of anti-angiogenic forms of VEGF VEGFxxxb which are still present in many tumors limit the therapeutic effects of the anti-VEGF antibodies bevacizumab/Avastin (BVZ). To test this hypothesis, we generated renal cell carcinoma cells (RCC) expressing VEGF165b. The incidence of tumors xenografts generated in nude mice and their growth were inferior to those obtained with control cells. Whereas BVZ had no effect on control tumors, it slowed-down the growth of tumor generated with VEGF165b expressing cells. A prophylactic immunization against the domain discriminating VEGF from VEGFxxxb isoforms inhibited the growth of tumor generated with two different syngenic tumor cell lines (melanoma (B16 cells) and RCC (RENCA cells)). Purified immunoglobulins from immunized mice also slowed-down tumor growth of human RCC xenografts in nude mice, producing a potent effect compared to BVZ in this model. Furthermore, down-regulating the serine-arginine-rich splicing factor 1 (SRSF1) or masking SRSF1 binding sites by 2'O-Methyl RNA resulted in the increase of the VEGFxxxb/VEGF ratio. Therefore, a vaccine approach, specific antibodies against pro-angiogenic forms of VEGF, or increasing the VEGFxxxb/VEGF ratio may represent new prophylactic or pro-active anti-cancer strategies.

Heterogeneity in renal cell carcinoma

INTRODUCTION

In recent years, molecular characterization of renal cell carcinoma has facilitated the identification of driver genes, specific molecular pathways, and characterization of the tumor microenvironment, which has led to a better understanding of the disease. This comprehension has revolutionized the treatment for patients with metastatic disease, but despite these advancements many patients will develop resistance leading to treatment failure. A primary cause of this resistance and subsequent treatment failure is tumor heterogeneity. We reviewed the literature on the mechanisms of tumor heterogeneity and its clinical implications.

METHODS

A comprehensive literature search was performed using the MEDLINE/PubMed Index.

RESULTS

Intertumor and intratumor heterogeneity is possibly a reason for treatment failure and development of resistance. Specifically, the genetic profile of a renal tumor differs spatially within a tumor as well as among patients. Genomic mutations can change temporally with resistant subclones becoming dominant over time.

CONCLUSIONS

Accounting for intratumor and intertumor heterogeneity with better sampling of cancer tissue is needed. This will hopefully lead to improved identification of driver mutations and actionable targets. Only then, we can move past the one-size-fits-all approach toward personalized treatment based on each individual׳s molecular profile.

Sunitinib Stimulates Expression of VEGFC by Tumor Cells and Promotes Lymphangiogenesis in Clear Cell Renal Cell Carcinomas

Sunitinib is an antiangiogenic therapy given as a first-line treatment for renal cell carcinoma (RCC). While treatment improves progression-free survival, most patients relapse. We hypothesized that patient relapse can stem from the development of a lymphatic network driven by the production of the main growth factor for lymphatic endothelial cells, VEGFC. In this study, we found that sunitinib can stimulate vegfc gene transcription and increase VEGFC mRNA half-life. In addition, sunitinib activated p38 MAPK, which resulted in the upregulation/activity of HuR and inactivation of tristetraprolin, two AU-rich element-binding proteins. Sunitinib stimulated a VEGFC-dependent development of lymphatic vessels in experimental tumors. This may explain our findings of increased lymph node invasion and new metastatic sites in 30% of sunitinib-treated patients and increased lymphatic vessels found in 70% of neoadjuvant treated patients. In summary, a therapy dedicated to destroying tumor blood vessels induced the development of lymphatic vessels, which may have contributed to the treatment failure. Cancer Res; 77(5); 1212-26. ©2017 AACR.

Therapeutic Drug Monitoring of Everolimus: A Consensus Report

In 2014, the Immunosuppressive Drugs Scientific Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology called a meeting of international experts to provide recommendations to guide therapeutic drug monitoring (TDM) of everolimus (EVR) and its optimal use in clinical practice. EVR is a potent inhibitor of the mammalian target of rapamycin, approved for the prevention of organ transplant rejection and for the treatment of various types of cancer and tuberous sclerosis complex. EVR fulfills the prerequisites for TDM, having a narrow therapeutic range, high interindividual pharmacokinetic variability, and established drug exposure-response relationships. EVR trough concentrations (C0) demonstrate a good relationship with overall exposure, providing a simple and reliable index for TDM. Whole-blood samples should be used for measurement of EVR C0, and sampling times should be standardized to occur within 1 hour before the next dose, which should be taken at the same time everyday and preferably without food. In transplantation settings, EVR should be generally targeted to a C0 of 3-8 ng/mL when used in combination with other immunosuppressive drugs (calcineurin inhibitors and glucocorticoids); in calcineurin inhibitor-free regimens, the EVR target C0 range should be 6-10 ng/mL. Further studies are required to determine the clinical utility of TDM in nontransplantation settings. The choice of analytical method and differences between methods should be carefully considered when determining EVR concentrations, and when comparing and interpreting clinical trial outcomes. At present, a fully validated liquid chromatography tandem mass spectrometry assay is the preferred method for determination of EVR C0, with a lower limit of quantification close to 1 ng/mL. Use of certified commercially available whole-blood calibrators to avoid calibration bias and participation in external proficiency-testing programs to allow continuous cross-validation and proof of analytical quality are highly recommended. Development of alternative assays to facilitate on-site measurement of EVR C0 is encouraged.

Resistance to sunitinib in renal clear cell carcinoma results from sequestration in lysosomes and inhibition of the autophagic flux

Metastatic renal cell carcinomas (mRCC) are highly vascularized tumors that are a paradigm for the treatment with antiangiogenesis drugs targeting the vascular endothelial growth factor (VEGF) pathway. The available drugs increase the time to progression but are not curative and the patients eventually relapse. In this study we have focused our attention on the molecular mechanisms leading to resistance to sunitinib, the first line treatment of mRCC. Because of the anarchic vascularization of tumors the core of mRCC tumors receives only suboptimal concentrations of the drug. To mimic this in vivo situation, which is encountered in a neoadjuvant setting, we exposed sunitinib-sensitive mRCC cells to concentrations of sunitinib below the concentration of the drug that gives 50% inhibition of cell proliferation (IC50). At these concentrations, sunitinib accumulated in lysosomes, which downregulated the activity of the lysosomal protease CTSB (cathepsin B) and led to incomplete autophagic flux. Amino acid deprivation initiates autophagy enhanced sunitinib resistance through the amplification of autolysosome formation. Sunitinib stimulated the expression of ABCB1 (ATP-binding cassette, sub-family B [MDR/TAP], member 1), which participates in the accumulation of the drug in autolysosomes and favor its cellular efflux. Inhibition of this transporter by elacridar or the permeabilization of lysosome membranes with Leu-Leu-O-methyl (LLOM) resensitized mRCC cells that were resistant to concentrations of sunitinib superior to the IC50. Proteasome inhibitors also induced the death of resistant cells suggesting that the ubiquitin-proteasome system compensates inhibition of autophagy to maintain a cellular homeostasis. Based on our results we propose a new therapeutic approach combining sunitinib with molecules that prevent lysosomal accumulation or inhibit the proteasome.

Chrysin-organogermanium (IV) complex induced Colo205 cell apoptosis-associated mitochondrial function and anti-angiogenesis

Colorectal cancer, a kind of malignant cancer, has more than 1 million new patients and results in 0.5 million deaths every year globally based on the estimation of Globocan in 2008. One of the most important issues against colon cancer is tumor metastasis. Anti-angiogenesis, a form of targeted therapy uses drugs or other substances to prevent the new blood vessel formation, which is critical for tumor metastasis. In our previous studies, we have demonstrated a simple method to synthesize Chry-Ge complex through the reaction between chrysin and triphenylgermanium bromide. In this work, we investigated the mechanism of Chry-Ge induced Colo205 cell apoptosis. We found that Chry-Ge could induce apoptosis in Colo205 cells in mitochondrial-dependent pathway, cause the reorganization of cytoskeleton and induce the damage of nucleus in Colo205 cells. Besides, Chry-Ge was also found to induce membrane ultrastructural changes in Colo205 cells by AFM. Further, we found that Chry-Ge can inhibit tube formation of human umbilical vascular endothelial cell in vitro. Chry-Ge was also tested in vivo in the chicken chorioallantoic membrane (CAM) assay and found to inhibit bFGF-treated CAMs development. These results suggested that Chry-Ge could induce Colo205 cell apoptosis by mitochondrial pathway and anti-angiogenesis, highlighting the use of organic germanium agents for the treatment of colorectal cancer.