Pharmacokinetic and clinical phase II trial of imatinib in patients with impaired liver function and advanced hepatocellular carcinoma

Clinical pharmacokinetics and drug-drug interactions of tyrosine-kinase inhibitors in chronic myeloid leukemia: A clinical perspective

In the past decade, numerous tyrosine kinase inhibitors (TKIs) have been introduced in the treatment of chronic myeloid leukemia. Given the significant interpatient variability in TKIs pharmacokinetics, potential drug-drug interactions (DDIs) can greatly impact patient therapy. This review aims to discuss the pharmacokinetic characteristics of TKIs, specifically focusing on their absorption, distribution, metabolism, and excretion profiles. Additionally, it provides a comprehensive overview of the utilization of TKIs in special populations such as the elderly, children, and patients with liver or kidney dysfunction. We also highlight known or suspected DDIs between TKIs and other drugs, highlighting various clinically relevant interactions. Moreover, specific recommendations are provided to guide haemato-oncologists, oncologists, and clinical pharmacists in managing DDIs during TKI treatment in daily clinical practice.

Small Molecule Inhibitors for Hepatocellular Carcinoma: Advances and Challenges

According to data provided by World Health Organization, hepatocellular carcinoma (HCC) is the sixth most common cause of deaths due to cancer worldwide. Tremendous progress has been achieved over the last 10 years developing novel agents for HCC treatment, including small-molecule kinase inhibitors. Several small molecule inhibitors currently form the core of HCC treatment due to their versatility since they would be more easily absorbed and have higher oral bioavailability, thus easier to formulate and administer to patients. In addition, they can be altered structurally to have greater volumes of distribution, allowing them to block extravascular molecular targets and to accumulate in a high concentration in the tumor microenvironment. Moreover, they can be designed to have shortened half-lives to control for immune-related adverse events. Most importantly, they would spare patients, healthcare institutions, and society as a whole from the burden of high drug costs. The present review provides an overview of the pharmaceutical compounds that are licensed for HCC treatment and other emerging compounds that are still investigated in preclinical and clinical trials. These molecules are targeting different molecular targets and pathways that are proven to be involved in the pathogenesis of the disease.

C-Kit, a Double-Edged Sword in Liver Regeneration and Diseases

Previous studies have reported an important role of c-kit in embryogenesis and adulthood. Activation of the SCF/KIT signal transduction pathway is customarily linked to cell proliferation, migration and survival thus influence hematopoiesis, pigmentation, and spermatogenesis. The role of c-kit in the liver is controversial, it is however argued that it is a double-edged sword in liver regeneration and diseases. First, liver c-kit⁺ cells, including oval cells, bile epithelial cells, and part of hepatocytes, participate in liver tissue repair by regenerating target cells according to the type of liver injury. At the same time, c-kit⁺ mast cells, act as immature progenitors in circulation, playing a critical role in liver fibrosis. Furthermore, c-kit is also a proto-oncogene. Notably, c-kit overexpression regulates gastrointestinal stromal tumors. Various studies have explored on c-kit and hepatocellular carcinoma, nevertheless, the intricate roles of c-kit in the liver are largely understudied. Herein, we extensively summarize previous studies geared toward providing hints for future clinical and basic research.

Tumor Microenvironment-Associated Pericyte Populations May Impact Therapeutic Response in Thyroid Cancer

Thyroid cancer is the most common endocrine malignancy, and aggressive radioactive iodine refractory thyroid carcinomas still lack an effective treatment. A deeper understanding of tumor heterogeneity and microenvironment will be critical to establishing new therapeutic approaches. One of the important influencing factors of tumor heterogeneity is the diversity of cells in the tumor microenvironment. Among these are pericytes, which play an important role in blood vessel stability and angiogenesis, as well as tumor growth and metastasis. Pericytes also have stem cell-like properties and are a heterogeneous cell population, and their lineage, which has been challenging to define, may impact tumor resistance at different tumor stages. Pericytes are also important stroma cell types in the angiogenic microenvironment which express tyrosine-kinase (TK) pathways (e.g., PDGFR-β). Although TK inhibitors (TKI) and BRAF^V600E inhibitors are currently used in the clinic for thyroid cancer, their efficacy is not durable and drug resistance often develops. Characterizing the range of distinct pericyte populations and distinguishing them from other perivascular cell types may enable the identification of their specific functions in the thyroid carcinoma vasculature. This remains an essential step in developing new therapeutic strategies. Also, assessing whether thyroid tumors hold immature and/or mature vasculature with pericyte populations coverage may be key to predicting tumor response to either targeted or anti-angiogenesis therapies. It is also critical to apply different markers in order to identify pericyte populations and characterize their cell lineage. This chapter provides an overview of pericyte ontogenesis and the lineages of diverse cell populations. We also discuss the role(s) and targeting of pericytes in thyroid carcinoma, as well as their potential impact on precision targeted therapies and drug resistance.

Overexpression of Platelet-Derived Growth Factor Receptor Α D842V Mutants Prevents Liver Regeneration and Chemically Induced Hepatocarcinogenesis via Inhibition of MET and EGFR

Platelet-derived growth receptor α (PDGFRα) is a key factor in many pathophysiological processes. The expression level of PDGFRα is significantly elevated in the early stage of liver development and maintained at a lower level in adult normal livers. In this study, we constructed a liver-specific PDGFRαD842 mutant transgenic (TG) mice model to explore the effect of continuous activation of PDGFRα on liver regeneration and hepatocarcinogenesis. 14-day-old TG and wild-type (WT) mice were intraperitoneally injected with diethylnitrosamine (DEN) at a dose of 25 μg/g body weight. Two-month-old male TG and WT mice were subjected to partial hepatectomy (PH). The liver tissues were collected for further analysis at different time points. Overexpression of PDGFRα ^D842V and its target genes, Akt, c-myc and cyclin D1 in hepatocytes with no overt phenotype versus WT mice were compared. Unexpectedly, a dramatic decrease in hepatocyte proliferation was noted after PH in TG versus WT mice, possibly due to the downregulation of hepatocyte growth factor receptor (MET) and epidermal growth factor receptor (EGFR). No TG mice developed HCC spontaneously after 14 months follow-up. However, TG mice were more resistant to DEN-induced hapatocarcinogenesis at 6, 10, and 12 months of age, showing delayed hepatocyte proliferation and apoptosis, lower tumor incidence, smaller size and fewer number, compared with age-matched WTs, partially through downregulation of MET and EGFR. In conclusion, continuous activation of PDGFRα signaling by expression of PDGFRα ^D842V does not promote, but inhibit hepatic regeneration and hepatocarcinogenesis, possibly through compensatory downregulation of MET and EGFR.

Cancer and liver cirrhosis: implications on prognosis and management

Liver cirrhosis, the end-stage of every chronic liver disease, is not only the major risk factor for the development of hepatocellular carcinoma but also a limiting factor for anticancer therapy of liver and non-hepatic malignancies. Liver cirrhosis may limit surgical and interventional approaches to cancer treatment, influence pharmacokinetics of anticancer drugs, increase side effects of chemotherapy, render patients susceptible for hepatotoxicity, and ultimately result in a competitive risk for morbidity and mortality. In this review, we provide a concise overview about the impact of liver cirrhosis on the management and prognosis of patients with primary liver cancer or non-hepatic malignancies.

Dysregulated miRNA in progression of hepatocellular carcinoma: A systematic review

Hepatocellular carcinoma (HCC) is the fifth most frequent cancer and the third cause of cancer-related mortality worldwide. The primary risk factor for HCC is liver cirrhosis secondary to persistent infection with hepatitis B virus or hepatitis C virus. Although a number of cellular phenomena and molecular events have been reported to facilitate tumor initiation, progression and metastasis, the exact etiology of HCC has not yet been fully uncovered. miRNA, a class of non-coding RNA, negatively regulate post-transcriptional processes that participate in crucial biological processes, including development, differentiation, apoptosis and proliferation. In the liver, specific miRNA can be negative regulators of gene expression. Recent studies have uncovered the contribution of miRNA to cancer pathogenesis as they can function as oncogenes or tumor suppressor genes. In addition, other studies have demonstrated their potential value in the clinical management of patients with HCC as some miRNA may be used as prognostic or diagnostic markers. In this review, we summarize the current knowledge about the roles of miRNA in the carcinogenesis and progression of HCC.

Host cellular microRNA involvement in the control of hepatitis B virus gene expression and replication

A large number of studies have demonstrated that the synergistic collaboration of a number of microRNAs (miRNAs), their growth factors and their downstream agents is required for the initiation and completion of pathogenesis in the liver. miRNAs are thought to exert a profound effect on almost every aspect of liver biology and pathology. Accumulating evidence indicates that several miRNAs are involved in the hepatitis B virus (HBV) life cycle and infectivity, in addition to HBV-associated liver diseases including fibrosis, cirrhosis and hepatocellular carcinoma (HCC). In turn, HBV can modulate the expression of several cellular miRNAs, thus promoting a favorable environment for its replication and survival. In this review, we focused on the involvement of host cellular miRNAs that are directly and indirectly associated with HBV RNA or HBV associated transcription factors. Exploring different facets of the interactions among miRNA, HBV and HCV infections, and the carcinogenesis and progress of HCC, could facilitate the development of novel and effective treatment approaches for liver disease.

Differential effects of sorafenib on liver versus tumor fibrosis mediated by stromal-derived factor 1 alpha/C-X-C receptor type 4 axis and myeloid differentiation antigen-positive myeloid cell infiltration in mice

Sorafenib--a broad kinase inhibitor--is a standard therapy for advanced hepatocellular carcinoma (HCC) and has been shown to exert antifibrotic effects in liver cirrhosis, a precursor of HCC. However, the effects of sorafenib on tumor desmoplasia--and its consequences on treatment resistance--remain unknown. We demonstrate that sorafenib has differential effects on tumor fibrosis versus liver fibrosis in orthotopic models of HCC in mice. Sorafenib intensifies tumor hypoxia, which increases stromal-derived factor 1 alpha (SDF-1α) expression in cancer and stromal cells and, subsequently, myeloid differentiation antigen-positive (Gr-1(+)) myeloid cell infiltration. The SDF-1α/C-X-C receptor type 4 (CXCR4) pathway directly promotes hepatic stellate cell (HSC) differentiation and activation through the mitogen-activated protein kinase pathway. This is consistent with the association between SDF-1α expression with fibrotic septa in cirrhotic liver tissues as well as with desmoplastic regions of human HCC samples. We demonstrate that after treatment with sorafenib, SDF-1α increased the survival of HSCs and their alpha-smooth muscle actin and collagen I expression, thus increasing tumor fibrosis. Finally, we show that Gr-1(+) myeloid cells mediate HSC differentiation and activation in a paracrine manner. CXCR4 inhibition, using AMD3100 in combination with sorafenib treatment, prevents the increase in tumor fibrosis--despite persistently elevated hypoxia--in part by reducing Gr-1(+) myeloid cell infiltration and inhibits HCC growth. Similarly, antibody blockade of Gr-1 reduces tumor fibrosis and inhibits HCC growth when combined with sorafenib treatment.

CONCLUSION

Blocking SDF-1α/CXCR4 or Gr-1(+) myeloid cell infiltration may reduce hypoxia-mediated HCC desmoplasia and increase the efficacy of sorafenib treatment.

Practical guidelines for dose individualization of anticancer targeted drugs

For drugs such as anticancer agents every effort should be made to minimize inter-patient variability in drug exposure in order to maximize the benefit while maintaining an acceptable risk level of serious adverse effects. Anticancer drugs generally have a preferential route of elimination, either in urine or in bile and feces. In consequence, dose individualization to renal and liver function permits excessive toxicity to be avoided and expected therapeutic benefit to be achieved. However, less is known about the most appropriate starting doses of antineoplastic agents in these individuals. In this review, we discuss trials that have specifically assessed new targeted agents dosing strategies (mainly monoclonal antibodies and tyrosine kinase inhibitors) in the setting of overt biochemical renal and liver dysfunction and we proportionate recommendations and practical guidelines for dose individualization.

Novel inhibitors in development for hepatocellular carcinoma

IMPORTANCE OF THE FIELD

The multikinase inhibitor sorafenib was the first agent to demonstrate a survival benefit for patients with locally advanced or metastatic hepatocellular carcinoma (HCC). Although sorafenib represents a landmark in the treatment of HCC and proved molecularly targeted therapy to be effective in this disease, it represents just the first step towards an improvement in systemic therapy. Since then, novel inhibitors have been evaluated in early clinical trials, showing potential activity.

AREAS COVERED IN THIS REVIEW

This article aims to review novel inhibitors emerging in the field of advanced HCC. An Internet-based search was performed to identify abstracts, clinical trials ( www.clinicaltrials.gov , last accessed 30 November 2009), and original research and review articles.

WHAT THE READER WILL GAIN

Readers will gain a comprehensive survey of current molecularly targeted therapy approaches in advanced HCC. In addition, challenges such as the design of clinical trials, the assessment of radiological response, the role of combination therapy, and future developments in molecularly targeted therapy are discussed.

TAKE HOME MESSAGE

Sorafenib is the standard of care in patients with advanced HCC. However, promising novel inhibitors are under investigation. Combined molecularly targeted therapies according to an individual genomic and proteomic profiling will probably lead to more personalised medicine in advanced HCC.

Platelet-Derived Growth Factor (PDGF)/PDGF Receptors (PDGFR) Axis as Target for Antitumor and Antiangiogenic Therapy

Angiogenesis in normal and pathological conditions is a multi-step process governed by positive and negative endogenous regulators. Many growth factors are involved in different steps of angiogenesis, like vascular endothelial growth factors (VEGF), fibroblast growth factor (FGF)-2 or platelet-derived growth factors (PDGF). From these, VEGF and FGF-2 were extensively investigated and it was shown that they significantly contribute to the induction and progression of angiogenesis. A lot of evidence has been accumulated in last 10 years that supports the contribution of PDGF/PDGFR axis in developing angiogenesis in both normal and tumoral conditions. The crucial role of PDGF-B and PDGFR-β in angiogenesis has been demonstrated by gene targeting experiments, and their expression correlates with increased vascularity and maturation of the vascular wall. PDGF and their receptors were identified in a large variety of human tumor cells. In experimental models it was shown that inhibition of PDGF reduces interstitial fluid pressure in tumors and enhances the effect of chemotherapy. PDGFR have been involved in the cardiovascular development and their loss leads to a disruption in yolk sac blood vessels development. PDGFRβ expression by pericytes is necessary for their recruitment and integration in the wall of tumor vessels. Endothelial cells of tumor-associated blood vessels can express PDGFR. Based on these data, it was suggested the potential benefit of targeting PDGFR in the treatment of solid tumors. The molecular mechanisms of PDGF/PDGFR-mediated angiogenesis are not fully understood, but it was shown that tyrosine kinase inhibitors reduce tumor growth and angiogenesis in experimental xenograft models, and recent data demonstrated their efficacy in chemoresistant tumors. The in vivo effects of PDGFR inhibitors are more complex, based on the cross-talk with other angiogenic factors. In this review, we summarize data regarding the mechanisms and significance of PDGF/PDGFR expression in normal conditions and tumors, focusing on this axis as a potential target for antitumor and antiangiogenic therapy.

Molecular targets for liver cancer therapy: From screening of target genes to clinical trials

Cancer arises from the accumulation of genetic alterations, and the inactivation of oncogenes, or recovery of suppressor genes, are promising strategies for cancer treatment. Genome-based drug research starts with identification of target genes and is accomplished by exploitation of target-based drugs such as monoclonal antibodies, small molecules and antisense drugs. Recently, clinical trials for treatment of advanced hepatocellular carcinoma (HCC) have been performed, and the effectiveness of sorafenib, an oral multikinase inhibitor of the vascular endothelial growth factor receptor and Ras kinase, has been demonstrated. In addition to known target genes, microarray technology has enabled us to constitute novel therapeutic targets, and many researchers have applied this technology in studies of HCC and have identified candidate target genes, validated to affect cell growth. In addition, promoter arrays for whole-genome epigenetic aberration analysis, ChIP-chip analysis using tiling arrays, and high-throughput sequencing systems have been applied to drug discovery. To elucidate the status of therapeutic target genes in vivo, development of diagnostic markers for stratification of patients is a pressing need. Here, we review recent advances in microarray technology for liver cancer, discuss the innovations and approaches to therapeutic target discovery, and present data regarding the outcome of gene target therapy using monoclonal antibodies and molecular diagnostic markers in our laboratory.

Clinical pharmacokinetics of tyrosine kinase inhibitors

In the recent years, eight tyrosine kinase inhibitors (TKIs) have been approved for cancer treatment and numerous are under investigation. These drugs are rationally designed to target specific tyrosine kinases that are mutated and/or over-expressed in cancer tissues. Post marketing study commitments have been made upon (accelerated) approval such as additional pharmacokinetic studies in patients with renal- or hepatic impairment, in children, additional interactions studies and studies on the relative or absolute bioavailability. Therefore, much information will emerge on the pharmacokinetic behavior of these drugs after their approval. In the present manuscript, the pharmacokinetic characteristics; absorption, distribution, metabolism and excretion (ADME), of the available TKIs are reviewed. Results from additional studies on the effect of drug transporters and drug-drug interactions have been incorporated. Overall, the TKIs reach their maximum plasma levels relatively fast; have an unknown absolute bioavailability, are extensively distributed and highly protein bound. The drugs are primarily metabolized by cytochrome P450 (CYP) 3A4 with other CYP-enzymes playing a secondary role. They are predominantly excreted with the feces and only a minor fraction is eliminated with the urine. All TKIs appear to be transported by the efflux ATP binding-cassette transports B1 and G2. Additionally these drugs can inhibit some of their own metabolizing enzymes and transporters making steady-state metabolism and drug-drug interactions both complex and unpredictable. By understanding the pharmacokinetic profile of these drugs and their similarities, factors that influence drug exposure will be better recognized and this knowledge may be used to limit sub- or supra-therapeutic drug exposure.

Liver cancer stem cells: implications for a new therapeutic target

Hepatocellular carcinoma (HCC) is an aggressive tumour with a poor prognosis. Current therapeutic strategies against this disease target mostly rapidly growing differentiated tumour cells. However, the result is often dismal due to the chemoresistant nature of this tumour type. Recent research efforts on stem cells and cancer biology have shed light on new directions for the eradication of cancer stem cells (CSCs) in HCC. The liver is a distinctive organ with the ability of tissue renewal in response to injury. Based on the hypothesis that cancer development is derived from the hierarchy of the stem cell system, we will briefly discuss the origin of liver stem cells and its relation to HCC development. We will also summarize the current CSC markers in HCC and discuss their relevance to the treatment of this deadly disease.

PDGFRalpha: a new therapeutic target in the treatment of hepatocellular carcinoma?

BACKGROUND

Hepatocellular carcinoma (HCC) develops most often in a background of chronic inflammatory liver injury from viral infection or alcohol use. Most HCCs are diagnosed at a stage at which surgical resection is not feasible. Even in patients receiving surgery rates of recurrence and metastasis remain high. There are few effective HCC therapies and hence a need for novel, rational approaches to treatment. Platelet derived growth factor receptor-alpha (PDGFR-alpha) is involved in tumor angiogenesis and maintenance of the tumor microenvironment and has been implicated in development and metastasis of HCC.

OBJECTIVE

To examine PDGFR-alpha as a target for therapy of HCC and explore opportunities and strategies for PDGFR-alpha inhibition.

METHODS

A review of relevant literature.

RESULTS/CONCLUSIONS

Targeted inhibition of PDGFR-alpha is a rational strategy for prevention and therapy of HCC.

Efficacy, safety, and potential biomarkers of sunitinib monotherapy in advanced hepatocellular carcinoma: a phase II study

PURPOSE

To assess the safety and efficacy of sunitinib in patients with advanced hepatocellular carcinoma (HCC) and explore biomarkers for sunitinib response.

PATIENTS AND METHODS

We conducted a multidisciplinary phase II study of sunitinib, an antivascular endothelial growth factor receptor tyrosine kinase inhibitor, in advanced HCC. Patients received sunitinib 37.5 mg/d for 4 weeks followed by 2 weeks of rest per cycle. The primary end point was progression-free survival (PFS). We used functional magnetic resonance imaging to evaluate vascular changes in HCC after sunitinib treatment. Circulating molecular and cellular biomarkers were evaluated before and at six time points after sunitinib treatment.

RESULTS

Thirty-four patients were enrolled. The objective response rate was 2.9%, and 50% of patients had stable disease. Median PFS was 3.9 months (95% CI, 2.6 to 6.9 months), and overall survival was 9.8 months (95% CI, 7.4 months to not available). Grade 3 or 4 toxicities included leukopenia/neutropenia, thrombocytopenia, elevation of aminotransferases, and fatigue. Sunitinib rapidly decreased vessel leakiness, and this effect was more pronounced in patients with delayed progression. When evaluated early (at baseline and day 14) as well as over three cycles of treatment, higher levels of inflammatory molecules (eg, interleukin-6, stromal-derived factor 1alpha, soluble c-KIT) and circulating progenitor cells were associated with a poor outcome.

CONCLUSION

Sunitinib shows evidence of modest antitumor activity in advanced HCC with manageable adverse effects. Rapid changes in tumor vascular permeability and circulating inflammatory biomarkers are potential determinants of response and resistance to sunitinib in HCC. Our study suggests that control of inflammation might be critical for improving treatment outcome in advanced HCC.

Pathogenesis of hepatocellular carcinoma and molecular therapies

PURPOSE OF REVIEW

Over the past decades, advances in the knowledge of the molecular pathogenesis of hepatocellular carcinoma (HCC) have allowed significant improvements in the therapeutic management of this devastating disease. Several investigations have established the role of aberrant activation of major intracellular signaling pathways during human hepatocarcinogenesis. Genome-wide analysis of DNA copy number changes and gene expression led to the identification of gene signatures and novel targets for cancer treatment. Numerous attempts have tried to develop a molecular classification of HCC. This review aims to summarize the most relevant genetic alterations and pathways involved in the development and progression of HCC, providing an overview of the molecular targeted therapies tested so far in human HCC.

RECENT FINDINGS

The discovery of sorafenib, a multikinase inhibitor, as a treatment with survival benefits in patients with advanced HCC, has become a major breakthrough in the clinical management of HCC. For the first time, a molecular therapy was able to demonstrate significant efficacy for the treatment of HCC patients. New guidelines have established the ideal endpoints for the design of clinical trials for HCC. At last, a molecular classification of HCC based on genome-wide investigations, able to identify patient subclasses according to drug sensitivity will lead to a more personalized medicine.

SUMMARY

In this review, we provide a comprehensive analysis of the underlying molecular mechanisms leading to human hepatocarcinogenesis, providing the scientific rationale for the development of new therapeutic targets.

MicroRNA involvement in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third cause of cancer-related death worldwide. Curative options for HCC are limited and exclusively available for patients carrying an early stage HCC. In advanced stages, traditional chemotherapy proved to be only marginally effective or even toxic. Thus, the identification of new treatment options is needed. New targets for non-conventional treatment will necessarily take advantage of progresses on the molecular pathogenesis of HCC. MicroRNAs (miRNAs) are a group of tiny RNAs with a fundamental role in the regulation of gene expression. Aberrant expression of several miRNAs was found to be involved in human hepatocarcinogenesis. miRNA expression signatures were correlated with bio-pathological and clinical features of HCC. In some cases, aberrantly expressed miRNAs could be linked to cancer-associated pathways, indicating a direct role in liver tumourigenesis. For example, up-regulation of mir-221 and mir-21 could promote cell cycle progression, reduce cell death and favour angiogenesis and invasion. These findings suggest that miRNAs could become novel molecular targets for HCC treatment. The demonstration of in vivo efficacy and safety of anti-miRNA compounds has opened the way to their use in clinical trials.

Sorafenib and rapamycin induce growth suppression in mouse models of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common malignancy worldwide. Vascular endothelial growth factor, platelet derived growth factor and the Raf/mitogen-activated protein kinase/extracellular signal regulated kinase (Raf/MEK/ERK) signalling pathway regulates the growth, neovascularization, invasiveness and metastatic potential of HCC. In this study, we investigated the in vivo antitumour activity and mechanisms of action of sorafenib tosylate on four patient-derived HCC xenografts. Sorafenib dosed at 50 mg/kg and 100 mg/kg inhibited tumour growth by 85% and 96%, respectively. Sorafenib-induced growth suppression and apoptosis were associated with inhibition of angiogenesis, down-regulation of phospho-platelet-derived growth factor receptor beta Tyr1021, phospho-eIF4E Ser209, phospho-c-Raf Ser259, c-Raf, Mcl-1, Bcl-2, Bcl-x and positive cell cycle regulators, up-regulation of apoptosis signalling kinase-1, p27 and p21. Expression of IGF-1Rbeta and phosphorylation of c-Raf Ser338, MEK1/2 Ser217/221 and ERK1/2 Thr202/Tyr204 were increased by sorafenib treatment. Phosphorylation of mammalian target-of-rapamycin (mTOR) targets (p70S6K, S6R and 4EBP1) was reduced by sorafenib in sorafenib-sensitive lines but activated in sorafenib-less-sensitive 10-0505 xenograft. Sorafenib-induced phosphorylation of c-met, p70S6K and 4EBP1 was significantly reduced when 10-0505 cells were co-treated with anti-human anti-HGF antibody, suggesting that treatment with sorafenib leads to increased HGF secretion and activation of c-met and mTOR targets. Treatment of 10-0505 tumours with sorafenib plus rapamycin resulted in growth inhibition, inhibition of vascular endothelial growth factor receptor-2 phosphorylation, increased apoptosis and completely blocked sorafenib-induced phosphorylation of mTOR targets and cyclin B1 expression. These data also provide a strong rationale for clinical investigation of sorafenib in combination with mTOR inhibitors in patients with HCC.

Selective targeting of the tumour vasculature

Selective targeting of the tumour vasculature in the treatment of solid organ malignancies is an alternative to conventional chemotherapy treatment. As the tumour progressively increases in size, angiogenesis or the formation of new vasculature is essential to maintain the tumour's continual growth and survival. Therefore disrupting this angiogenic process or targeting the neovasculature can potentially hinder or prevent further tumour expansion. Many anti angiogenic agents have been investigated with many currently in clinical trials and exhibiting varied results. Vascular disrupting agents such as the Combretastatins and OXi 4503 have shown promising preclinical results and are currently being examined in clinical trials.

Part II: Liver function in oncology: towards safer chemotherapy use

The liver is fundamentally important in drug metabolism. In oncology, the astute clinician must not only understand the meaning and limitations of commonly ordered liver biochemical tests, but also be aware of which anticancer agents might induce liver dysfunction, and of the strategies for appropriate dosing of patients with pre-existing liver dysfunction. In part I of our Review, we highlighted both the importance and inadequacies of identifying serum biochemical liver abnormalities in oncology; we also discussed a lack of routine formal investigation of liver function. We summarised chemotherapy-related hepatotoxicity and other causes of liver toxic effects in patients with cancer. Here in part II, we discuss trials that have specifically assessed chemotherapy dosing strategies in the setting of overt biochemical liver dysfunction and we note their recommendations. Furthermore, we review other assessments of liver metabolic and excretory function, particularly in the setting of chemotherapy drug handling. We discuss the potential use of these metabolic probes in practice.

Expression of c-kit protooncogen in hepatitis B virus-induced chronic hepatitis, cirrhosis and hepatocellular carcinoma: has it a diagnostic role?

AIM

There are more than 350 million people worldwide chronically infected with hepatitis B virus (HBV), who are at high risk for the development of hepatitis, cirrhosis and hepatocellular carcinoma (HCC). Because of the conflicting results about c-kit expression in HCC and the key role played by c-kit in gastrointestinal stromal tumours (GIST) and other solid tumours, the aim of this study was to determine c-kit expression in the course of hepatitis B infection.

MATERIALS AND METHODS

Paraffin-embedded tissues in Cukurova University Faculty of Medicine Department of Pathology between January 2002 and February 2006 were searched restrospectively to investigate this issue. We performed immunohistochemistry on biopsies of 125 patients with HBV infection, grouped as: mild, moderate and severe hepatitis, cirrhosis and HCC, 25 patients in each of them, using anti c-kit monoclonal antibody. The severity of parenchymal inflammation and of interface hepatitis was semiquantitatively graded on a haematoxylin and eosin stained paraffin sections. Additionally, 50 more HCC, formed on HBV basis, were studied to determine the prevalence of c-kit overexpression.

RESULTS

In cirrhotic liver, lower intensity of staining and rarely c-kit positivity were present. The greatest number of the c-kit positivity and higher intensity of staining was found in the livers of patients with severe hepatitis and HCC. In chronic hepatitis B infection, the staining intensity was parallel with the grade and stage of the disease. In the areas where fibrosis was seen, c-kit positivity was rare or absent. In the HCC specimens, c-kit positivity appeared both inside and around the cancerous nodes. C-kit expression was observed in 62 of 75 HCC tissue specimens (82%) (p < 0.001).

CONCLUSIONS

C-kit positivity was observed in the mitotic, proliferating and also dysplastic hepatic cells. These results suggest that c-kit expression may be used as an early diagnostic indicator for HBV induced HCC.

Linking molecular classification of hepatocellular carcinoma and personalized medicine: preliminary steps

PURPOSE OF REVIEW

The development of high-throughput technologies able to simultaneously investigate thousands of genes (e.g. single nucleotide polymorphism-array, gene expression microarray, etc.) has opened a new era in translational research. Obtaining a molecular classification of hepatocellular carcinoma, however, remains a striking challenge. This review summarizes the molecular classifications of hepatocellular carcinoma reported so far, analyzes the status of targeted therapies tested in clinical trials, and evaluates feasibility of personalized medicine approaches in hepatocellular carcinoma.

RECENT FINDINGS

Different investigators attempted to classify patients according to their liver cancer molecular background, a feature that will path the way for trial enrichment and personalized medicine. Currently, hepatocellular carcinoma can be classified in molecular classes according to Wnt-beta-catenin pathway activation, proliferation signature activation (associated with chromosomal instability), and other subgroups. In parallel, the first-time-ever positive results of a phase III trial in advanced hepatocellular carcinoma with the multikinase inhibitor sorafenib have encouraged this approach.

SUMMARY

Selection of patient candidates according to their tumor molecular background is a reality in human malignancies. Thus, a molecular classification is essential to allow the development of new targets, and to customize therapies in patients with hepatocellular carcinoma.

Phase II study of imatinib in unresectable hepatocellular carcinoma

BACKGROUND

The expression of platelet-derived growth factor, a potent mitogen, and its receptor both in tissue and serum correlate with the severity of liver cirrhosis. Over-expression of platelet-derived growth factor has been demonstrated in human hepatocellular carcinoma (HCC) tumors and cell lines. Imatinib, a potent inhibitor of BCR-ABL and c-kit, also inhibits the platelet-derived growth factor receptor tyrosine kinase. The trial was designed to assess the efficacy and safety of imatinib in patients with unresectable HCC.

METHODS

Eligibility criteria consisted of HCC patient over the age of 18 with reasonable organ function, unresectable but measurable disease, not candidates for chemoinfusion, and a performance status of 0 to 2. Imatinib was started at 300 mg/d orally with 100 mg/wk dose escalation up to 800 mg/d if toxicity permitted.

RESULTS

Fifteen patients, median age 58 years, were enrolled and treated with imatinib. Most, or 7, patients had hepatitis B virus as a risk factor for HCC, followed by hepatitis C virus in 3 patients. Metastatic disease (American Joint Committee on Cancer stage IV) was noted in 13 patients and locally advanced (stage III) in the remainder. The median dose-level of imatinib was 500 mg/d. Two patients had stable disease lasting more than 2 months. The remainder progressed within 2 months of initiation of imatinib. No grade 3 or 4 hematologic toxicity was observed. Two patients had grade 3 elevated liver function tests during treatment; otherwise, there was no other grade 3 or 4 nonhematologic toxicity noted.

CONCLUSION

Although toxicities were tolerable, imatinib as a monotherapy for the treatment of unresectable HCC has little, if any, significant efficacy.

Imatinib for hepatocellular cancer--focus on pharmacokinetic/pharmacodynamic modelling and liver function

The effects of imatinib are partly mediated by the inhibition of platelet-derived growth factor (PDGF), which is highly expressed in the liver. In this phase-I/II trial pharmacokinetic parameters of imatinib given for hepatocellular cancer were similar to those previously derived from CML patients. The AUC of N-desmethyl-imatinib depended on liver function; the metabolism of imatinib was otherwise comparable to other populations. During short-termed imatinib treatment (4 weeks, 400 mg/d), plasma PDGF significantly decreased. The AUC of N-desmethyl-imatinib could best be attributed to the pharmacodynamic effect of PDGF inhibition (r=-0.679 [95% CI: -0.917 to -0.0868], p=0.031).

[Molecular pathogenesis of hepatocellular carcinoma: new therapeutic approaches and predictive pathology]

Hepatocellular carcinoma is one of the most prevalent malignancies worldwide and its incidence is increasing. Multimodal strategies directed towards this carcinoma include primary (e.g. immunisation) and secondary (e.g. antiviral therapy) prevention, surgical approaches, novel specific systemic therapies (targeted therapy), and the treatment of comorbidity (cirrhosis). New molecular approaches are currently under development. These tackle several specific targets, with pathology being challenged in many aspects: experimental evaluation, the development of valid tumor-relevant diagnostic tests as well as morphological evaluation in the context of clinical studies, and finally in routine diagnosis.

Targeting stromal cells for the treatment of platelet-derived growth factor C-induced hepatocellular carcinogenesis

Non-invasive therapies for the treatment of hepatocellular carcinoma (HCC) would be of great benefit to public health. To this end, we have developed a platelet-derived growth factor-C (PDGF-C) transgenic (Tg) mouse model, which mimics many aspects of human liver carcinogenesis. Specifically, overexpression of PDGF-C results in liver fibrosis, which is preceded by activation and proliferation of hepatic stellate cells, and is followed by the development of dysplastic lesions and angiogenesis, and progression to HCCs by 8 months of age. Here, we show that PDGF-C overexpression induces the proliferation of endothelial-like cells that are present in tumors and adjacent non-neoplastic parenchyma. The protein tyrosine kinase inhibitor, imatinib (Gleevec), decreases the proliferation of non-parenchymal cells (NPC) in vitro and in vivo, with concomitant inhibition of Akt. In vivo treatment with imatinib also blocks the expression of CD34 in PDGF-C Tg mice. Decreased NPC proliferation and CD34 expression correlated with lower levels of active ERK1/2 and total levels of PDGF receptor alpha (PDGFRalpha). In summary, the small molecule inhibitor imatinib attenuates stromal cell proliferation in PDGF-C-induced HCC, which coincides with decreased expression of both CD34 and PDGFRalpha, and activated Akt. Our findings suggest that imatinib may be efficacious in the treatment of hepatocarcinogenesis, particularly when neovascularization is present.

Phase I and Pharmacokinetic Study of Imatinib Mesylate in Patients With Advanced Malignancies and Varying Degrees of Liver Dysfunction: A Study by the National Cancer Institute Organ Dysfunction Working Group

Purpose

To develop dosing guidelines and to evaluate the pharmacokinetics of imatinib in patients with liver dysfunction (LD).

Patients and Methods

Patients (N = 89) with varying solid tumors and liver function were stratified into four groups according to serum total bilirubin and AST and were treated with escalating doses of imatinib. Plasma and urine were assayed for concentrations of imatinib and its active metabolite, CGP74588 .

Results

In the mild LD group, dose-limiting toxicity, specifically nausea/vomiting and fatigue, occurred in two patients at the 600 mg/d dose level. In the moderate and severe LD groups, the maximal dose evaluated was 300 mg/d. Grade 3 to 4 toxicities consisted primarily of liver function test elevations (24%), nausea/vomiting (10%), fatigue (6%), and edema (5%). After the first imatinib dose, the mean (± SD) dose-normalized areas under the plasma concentration-time curve from time 0 to infinity (AUC0-∞) were 162 ± 155, 171 ± 72, 182 ± 157, and 185 ± 172 (μg/mL × h)/mg for normal, mild, moderate, and severe LD groups, respectively. Renal excretion of imatinib was less than 10% of the total dose in all groups.

Conclusion

Imatinib exposure (as measured by the dose-normalized AUC) did not differ between patients with normal liver function and those with LD. The maximal recommended dose of imatinib for patients with mild LD is 500 mg/d. Dosing guidelines for patients with moderate and severe LD remain undetermined.

Phase 2 study of erlotinib in patients with unresectable hepatocellular carcinoma

BACKGROUND

Growth factor overexpression, including epidermal growth factor receptor (EGFR) expression, is common in hepatocellular cancers. Erlotinib is a receptor tyrosine kinase inhibitor with specificity for EGFR. The primary objective of this study was to determine the proportion of hepatocellular carcinoma (HCC) patients treated with erlotinib who were alive and progression-free (PFS) at 16 weeks of continuous treatment.

METHODS

Patients with unresectable HCC, no prior systemic therapy, performance status (PS) of 0, 1, or 2, and Childs-Pugh (CP) cirrhosis A or B received oral erlotinib 150 mg daily for 28-day cycles. Tumor response was assessed every 2 cycles by using Response Evaluation Criteria in Solid Tumors (RECIST; National Cancer Institute Cancer Therapy Evaluation Program, Bethesda, Md) criteria. Patients accrued to either "low" or "high" EGFR expression cohorts; each cohort had stopping rules applied when there was a lack of efficacy.

RESULTS

Forty HCC patients were enrolled. Median age was 64 years (range, 33-83 years), sex distribution was 32 males and 8 females, performance scores were 40% PS 0, 55% PS 1, Childs-Pugh distribution was 75% A and 20% B. There were no complete or partial responses; however, 17 of 40 patients achieved stable disease at 16 weeks of continuous therapy. The PFS at 16 weeks was 43%, and the median overall survival (OS) was 43 weeks (10.75 months). No patients required dose reductions of erlotinib. No correlation between EGFR expression and outcome was found.

CONCLUSIONS

Results of this study indicated that single-agent erlotinib is well tolerated and has modest disease-control benefit in HCC, manifested as modestly prolonged PFS and OS when compared with historical controls.

Synthesis and positron emission tomography studies of carbon-11-labeled imatinib (Gleevec)

INTRODUCTION

Imatinib mesylate (Gleevec) is a well known drug for treating chronic myeloid leukemia and gastrointestinal stromal tumors. Its active ingredient, imatinib ([4-[(4-methyl-1-piperazinyl)methyl]-N-[4-methyl-3-[[4-(3-pyridyl)-2-pyrimidinyl]amino]phenyl]benzamide), blocks the activity of several tyrosine kinases. Here we labeled imatinib with carbon-11 as a tool for determining the drug distribution and pharmacokinetics of imatinib, and we carried out positron emission tomography (PET) studies in baboons.

METHODS

[N-(11)C-methyl]imatinib was synthesized from [(11)C]methyl iodide and norimatinib was synthesized by the demethylation of imatinib (isolated from Gleevec tablets) according to a patent procedure [Collins JM, Klecker RW Jr, Anderson LW. Imaging of drug accumulation as a guide to antitumor therapy. US Patent 20030198594A1, 2003]. Norimatinib was also synthesized from the corresponding amine and acid. PET studies were carried out in three baboons to measure pharmacokinetics in the brain and peripheral organs and to determine the effect of a therapeutic dose of imatinib. Log D and plasma protein binding were also measured.

RESULTS

[N-(11)C-methyl]imatinib uptake in the brain is negligible (consistent with P-glycoprotein-mediated efflux); it peaks and clears rapidly from the heart, lungs and spleen. Peak uptake and clearance occur more slowly in the liver and kidneys, followed by accumulation in the gallbladder and urinary bladder. Pretreatment with imatinib did not change uptake in the heart, lungs, kidneys and spleen, and increased uptake in the liver and gallbladder.

CONCLUSIONS

[N-(11)C-methyl]imatinib has potential for assessing the regional distribution and kinetics of imatinib in the human body to determine whether the drug targets tumors and to identify other organs to which the drug or its labeled metabolites distribute. Paired with tracers such as 2'deoxy-2'-[(18)F]fluoro-D-glucose ((18)FDG) and 3'deoxy-3'-[(18)F]fluorothymidine ((18)FLT), [N-(11)C-methyl]imatinib may be a useful radiotracer for planning chemotherapy, for monitoring response to treatment and for assessing the role of drug pharmacokinetics in drug resistance.

CD117 (c-kit) expression in human hepatocellular carcinoma

AIMS

Although various methods of treatment have been tried, treatment options for advanced hepatocellular carcinoma (HCC) remain limited. Expression of the platelet-derived growth factor has been shown in HCC, which may derive from hepatic stem cells that express the c-kit proto-oncogene. Because of the promising results of imatinib and the key role played by c-kit in gastrointestinal stromal tumours and other solid tumours, the aim of this study was to determine the prevalence of c-kit (CD117) overexpression in patients with HCC.

MATERIALS AND METHODS

A retrospective study of 258 archival specimens of subjects with histologically confirmed HCC was carried out. Expression of the c-kit proto-oncogene was evaluated by immunohistochemistry using rabbit anti-CD117 antibody A4502.

RESULTS

The overall percentage of positive immunohistochemical staining of HCCs was 2.3% (6/258).

CONCLUSIONS

Our results suggest that CD117 is not significantly overexpressed in HCC and there seems to be no role for the use of imatinib.

Pharmacokinetic-Pharmacodynamic Relationships of Imatinib and Its Main Metabolite in Patients with Advanced Gastrointestinal Stromal Tumors

PURPOSE

This study explored factors affecting the pharmacokinetic variability of imatinib and CGP 74588, and the pharmacokinetic-pharmacodynamic correlations in patients with advanced gastrointestinal stromal tumors.

EXPERIMENTAL DESIGN

Thirty-five patients with advanced gastrointestinal stromal tumors received 400 mg of imatinib daily. Six blood samples were drawn: before intake, during 1- to 3- and 6- to 9-hour intervals after intake on day 1, and before intake on days 2, 30, and 60. Plasma imatinib and CGP 74588 concentrations were quantified by reverse-phase high-performance liquid chromatography coupled with tandem mass spectrometry, and analyzed by the population pharmacokinetic method (NONMEM program). The influence of 17 covariates on imatinib clearance (CL) and CGP 74588 clearance (CLM/fm) was studied. These covariates included clinical and biological variables and occasion (OCC = 0 for pharmacokinetic data corresponding to the first administration, or OCC = 1 for the day 30 or 60 administrations).

RESULTS

The best regression formulas were: CL (L/h) = 7.97 (AAG/1.15)(-0.52), and CLM/fm (L/h) = 58.6 (AAG/1.15)(-0.60) x 0.55(OCC), with the plasma alpha1-acid glycoprotein (AAG) levels indicating that both clearance values decreased at a higher AAG level. A significant time-dependent decrease in CLM/fm was evidenced with a mean (+SD) CGP 74588/imatinib area under the curve (AUC) ratio of 0.25 (+/-0.07) at steady state, compared with 0.14 (+/-0.03) on day 1. Hematologic toxicity was correlated with pharmacokinetic variables: the correlation observed with the estimated unbound imatinib AUC at steady-state (r = 0.56, P < 0.001) was larger than that of the total imatinib AUC (r = 0.32, NS).

CONCLUSIONS

The plasma AAG levels influenced imatinib pharmacokinetics. A protein-binding phenomenon needs to be considered when exploring the correlations between pharmacokinetics and pharmacodynamics.

Emerging drugs for hepatocellular carcinoma

Hepatocellular carcinoma is often diagnosed at an advanced stage, when potentially curative surgical or local ablative therapies are not feasible. There is no effective chemotherapy for hepatocellular carcinoma. Recent advances in cancer biology suggest that a limited number of signalling pathways may be responsible for uncontrolled cell proliferation, the major cellular alteration responsible for the cancer phenotype. Novel anticancer agents target these critical pathways, including the receptor tyrosine kinase pathways, the Wnt/beta-catenin signalling pathway, the ubiquitin/proteasome degradation pathway, the DNA methylation and histone deacetylation pathways, the PI3 kinase/AKT/mTOR pathway, angiogenic pathways, telomerase and the cell cycle. These agents hold promise for improving the outcome of patients with intermediate and advanced hepatocellular carcinoma. Because of the high prevalence of liver cirrhosis in hepatocellular carcinoma patients, to achieve long-term survival of the majority of patients, targeted anticancer therapies will need to be coupled with strategies aimed at reversing the progression of chronic liver disease.

Systemic Therapy of Advanced Hepatocellular Carcinoma: How Hopeful Should We Be?

Worldwide, hepatocellular carcinoma (HCC) is the fifth most common cancer and the third most common cause of cancer-related death. In the U.S., 18,510 new cancers of the liver and intrahepatic bile duct are expected in 2006, with an estimated 16,200 deaths. The incidence rates for HCC in the U.S. continued to rise steadily through 1998 and doubled during the period 1975-1995. Unresectable or metastatic HCC carries a poor prognosis, and systemic therapy with cytotoxic agents provides marginal benefit. A majority of HCC patients (>80%) presents with advanced or unresectable disease. Even for those with resected disease, the recurrence rate can be as high as 50% at 2 years. Because of the poor track record of systemic therapy in HCC, there has been a sense of nihilism for this disease in the oncology community for decades. However, with the arrival of newly developed molecularly targeted agents and the success of some of these agents in other traditionally challenging cancers, like renal cell carcinoma, there has recently been renewed interest in developing systemic therapy for HCC. This review attempts to concisely summarize the historical perspective and the current status of systemic therapy development in HCC.

Expression of c-kit receptor in human cholangiocarcinoma and in vivo treatment with imatinib mesilate in chimeric mice

AIM: To investigate the c-kit expression in biliary tract cancer cell lines and histological sections from patients with extrahepatic cholangiocarcinoma (CC) and to evaluate the efficacy of in vitro and in vitro treatment with imatinib mesilate.

METHODS: The protein expression of c-kit in the human biliary tract cancer cell lines Mz-ChA-2 and EGI-1 and histological sections from 19 patients with extrahepatic CC was assessed by immunoblotting, immunocytochemistry, and immunohistochemistry. The anti-proliferative effect of imatinib mesilate on biliary tract cancer cell lines Mz-ChA-2 and EGI-1 was studied in vitro by automated cell counting. In addition, immunodeficient NMRI mice (Taconic^TM) were subcutaneously injected with 5 x 10⁶ cells of cell lines MzChA-2 and EGI-1. After having reached a tumour volume of 200 mm³, daily treatment was started intraperitoneally with imatinib mesilate at a dose of 50 mg/kg or normal saline (NS). Tumor volume was calculated with a Vernier caliper. After 14 d, mice were sacrificed with tumors excised and tumor mass determined.

RESULTS: Immunoblotting revealed presence of c-kit in Mz-ChA-2 and absence in EGI-1 cells. Immunocytochemistry with c-kit antibodies displayed a cytoplasmatic and membraneous localization of receptor protein in Mz-ChA-2 cells and absence of c-kit in EGI-1 cells. c-kit was expressed in 7 of 19 (37%) extrahepatic human CC tissue samples, 2 showed a moderate and 5 a rather weak immunostaining. Imatinib mesilate at a low concentration of 5 µmol/L caused a significant growth inhibition in the c-kit positive cell line Mz-ChA-2 (31%), but not in the c-kit negative cell line EGI-1 (0%) (P < 0.05). Imatinib mesilate at an intermediate concentration of 10 µmol/L inhibited cellular growth of both cell lines (51% vs 57%). Imatinib mesilate at a higher concentration of 20 µmol/L seemed to have a general toxic effect on both cell lines. The IC₅₀ values were 9.7 µmol/L and 11 µmol/L, respectively. After 14 d of in vitro treatment with imatinib mesilate, using the chimeric mouse model, c-kit positive Mz-ChA-2 tumors had a significantly reduced volume and mass as compared to NS treatment (P < 0.05). In contrast to that, treatment of mice bearing c-kit negative EGI-1 tumors did not result in any change of tumor volume and mass as compared to NS treatment.

CONCLUSION: c-kit expression is detectable at a moderate to low protein level in biliary tract cancer. Imatinib mesilate exerts marked effects on tumor growth in vitro and in vitro dependent on the level of c-kit expression.