Phase I study of cetuximab, erlotinib, and bevacizumab in patients with advanced solid tumors

Improved Antitumor Outcomes for Colon Cancer Using Nanomicelles Loaded with the Novel Antitumor Agent LA67

Background

LA67 is a derivative of triptolide that exhibits strong antitumor activity. This derivative has a better safety profile than triptolide, but is limited by poor aqueous solubility.

Aim and Methods

To improve solubility and further increase therapeutic efficacy, we prepared LA67-loaded polymeric micelles (LA67-PMs) using a film hydration method. The physicochemical properties of LA67-PMs were investigated, and the antitumor activity of this formulation against Colon26 (C26) cancer cell line was evaluated in vitro and in vivo with LA67 as a control.

Results

Polymeric micelles containing LA67 had a particle size of 17.88 nm and a drug entrapment efficiency of 94.84%. This formulation dispersed completely in aqueous solution and exhibited slow, sustained release of LA67. Cellular uptake assay showed that LA67-PMs delivered LA67 to cancer cells with greater efficiency than free LA67, which resulted in increased LA67 accumulation in cancer cells. Cell counting kit 8 (CCK-8) assay showed that blank polymeric micelles (PMs) exhibited low toxicity and LA67-PMs exerted pronounced anti-proliferation effects against C26 cells. Furthermore, LA67-PMs induced apoptosis and repressed migration more effectively than free LA67. In vivo evaluation of antitumor activity showed that LA67-PMs inhibited tumor growth and distant organ metastasis to a greater extent than LA67, which resulted in improved survival rate. The potential mechanisms of these effects may have been induction of apoptosis, inhibition of cell proliferation, and neovascularization.

Conclusion

Our study showed that LA67-PMs may be a promising formulation for treatment of colon cancer.

Advanced malignancies treated with a combination of the VEGF inhibitor bevacizumab, anti-EGFR antibody cetuximab, and the mTOR inhibitor temsirolimus

BACKGROUND

Bevacizumab and temsirolimus are active agents in advanced solid tumors. Temsirolimus inhibits mTOR in the PI3 kinase/AKT/mTOR pathway as well as CYP2A, which may be a resistance mechanism for cetuximab. In addition, temsirolimus attenuates upregulation of HIF-1α levels, which may be a resistance mechanism for bevacizumab.

RESULTS

The median age of patients was 60 years (range, 23-80 years). The median number of prior systemic therapies was 3 (range, 1-6). The maximum tolerated dose (MTD) was determined to be bevacizumab 10 mg/kg biweekly, temsirolimus 5 mg weekly and cetuximab 100/75 mg/m2 weekly. Grade 3 or 4 toxicities were seen in 52% of patients with the highest prevalence being hyperglycemia (14%) and hypophosphatemia (14%). Eighteen of the 21 patients were evaluable for response. Three patients were taken off the study before restaging for toxicities. Partial response (PR) was observed in 2/18 patients (11%) and stable disease (SD) lasting ≥ 6 months was observed in 4/18 patients (22%) (total = 6/18 (33%)). In 8 evaluable patients with squamous cell carcinoma of the head and neck (HNSCC) there were partial responses in 2/8 (25%) patients and SD ≥ 6 months in 1/8 (13%) patients (total = 3/8, (38%)).

PATIENTS AND METHODS

We analyzed safety and responses in 21 patients with advanced solid tumors treated with bevacizumab, cetuximab, and temsirolimus.

CONCLUSION

The combination of bevacizumab, cetuximab, and temsirolimus showed activity in HNSCC; however, there were numerous toxicities reported, which will require careful management for future clinical development.

Anti-EGFR monoclonal antibodies for treatment of colorectal cancers: development of cetuximab and panitumumab

Over the last decade, anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) have been firmly established as essential drugs for the treatment of metastatic colorectal cancer (CRC). Cetuximab and panitumumab have been approved by American and European drug agencies. This review aims at exploring the main outcomes of clinical studies performed during their clinical development, from phase I to III trials, and hence at giving a comprehensive review of the scientific rational and up-to-date evidence sustaining the use of these drugs. Many areas are still under active investigation such as administration schedules, their efficacy in comparison with bevacizumab, their role in adjuvant therapy, molecular predictors, and management of side effects.

Role of EMT in gastrointestinal tract tumors

Epithelial-mesenchymal transition (EMT) refers to the process by which cells transit from epithelial phenotype to mesenchymal phenotype. EMT is important for embryonic development, wound healing, and invasion of carcinomas. The molecular mechanisms of EMT are a hot topic of research in invasion and migration of malignant tumors, especially digestive carcinomas. Since malignant epithelial tumors account for a large proportion of tumors and are associated with very poor outcome and prognosis, exploration of the process of epithelial cell migration and invasion is of great significance for the prevention and treatment of tumors. The investigation of EMT provides a basis for understanding the pathogenesis of tumors and their prognosis and resistance to antitumor drugs. This review focuses on the molecular mechanisms and role of EMT in gastrointestinal tract tumors.

Dual targeting of the epidermal growth factor receptor using the combination of cetuximab and erlotinib: preclinical evaluation and results of the phase II DUX study in chemotherapy-refractory, advanced colorectal cancer

PURPOSE

This preclinical and phase II study evaluated the efficacy and safety of the combination of cetuximab and erlotinib in metastatic colorectal cancer (mCRC).

PATIENTS AND METHODS

The activity and mechanism of action of the combination of cetuximab plus erlotinib were investigated in vitro in colorectal cancer cell lines. In the clinical study, patients with chemotherapy-refractory mCRC were treated with cetuximab 400 mg/m(2) as a loading dose and then weekly cetuximab 250 mg/m(2) with erlotinib 100 mg orally daily. The primary end point was response rate (RR), which was evaluated separately in KRAS wild-type (WT) versus KRAS mutant tumors. Secondary end points included toxicity, progression-free survival (PFS), and overall survival. Target accrual was 50 patients, with a one-stage design.

RESULTS

Preclinical studies demonstrated synergistic activity of cetuximab and erlotinib cotreatment on growth inhibition of colon cancer cell lines both as a result of enhanced inhibition of the epidermal growth factor receptor pathway and differential effects on STAT3. In the clinical study, 50 patients were enrolled, with 48 patients evaluable for response. The overall RR was 31% (95% CI, 26% to 57%), with a median PFS of 4.6 months (95% CI, 2.8 to 5.6 months). RR was 41% (95% CI, 26% to 57%) in KRAS WT tumors, with a median PFS of 5.6 months (95% CI, 2.9 to 5.6 months). There was no response in 11 patients with KRAS mutations. Frequent grade 3 and 4 toxicities were rash (48%), hypomagnesaemia (18%), and fatigue (10%).

CONCLUSION

The combination of cetuximab and erlotinib synergistically inhibits growth of colon cancer cell lines, achieves promising efficacy in patients with KRAS WT mCRC, and merits evaluation in further randomized studies.

Chemoprevention in colorectal cancer--where we stand and what we have learned from twenty year's experience

INTRODUCTION

Colorectal chemoprevention is a strategy aimed at preventing tumour progression before irreversible changes to the proteome are in full progress. Chemoprevention is not a new concept. In fact, medical practitioners since the early 19th century have tried various herbal and medicinal products as methods that could prevent tumours. The current understanding of tumourigenesis and cellular signalling focuses on a more targeted approach and paves the way for better understanding of colorectal chemoprevention.

METHODS

The online databases PubMed, Medline, Medscape Oncology and Scirrus were searched for articles of relevance. The Keyword involved the following words: "Colorectal Cancer Chemoprevention", "Colorectal Cancer", "Chemoprevention", "Adenoma-Carcinoma Sequence" and "Colorectal Polyps". The search was started from the period of June 1995 until September 2010 inclusive.

RESULTS

More than 50 natural and synthetic compounds have been shown to have chemotherapeutic effect but the majority of these agents are still in their early experimental stages and hence far from our subject of discussion. Our discussion will focus on large scale randomised trials on human subjects or established compounds. Within the context of chemoprevention, Non-steroidal anti-inflammatory agents have undergone extensive research and have shown promising results with large scale randomised trials. Additionally, metformin, resveratrol, Histone deacetylase inhibitors, Src kinases as well monoclonal antibodies have shown promising results as well.

CONCLUSION

Colorectal cancer is the fourth most common cancer in the world. In the UK alone the number of cases reported in 2008 was almost 40,000 which make it the third most common tumour nationwide. Curative intent surgery or Colectomy is the treatment of choice for most cases of bowel cancer; however, in a select subpopulation of patients who have been colonoscopically diagnosed to harbour pre-malignant lesions, have a family history of colorectal cancer, or have been genetically diagnosed and treated surgically for colorectal tumours; chemoprevention might play a crucial role in deterring further tumour progression. The very latest studies that are in publication or are just accruing results are giving us encouraging data that might suggest whether mass scale ingestion of a specific medication might deter colorectal tumour progression.

Survivin-mediated cancer cell migration through GRP78 and epithelial-mesenchymal transition (EMT) marker expression in Mahlavu cells

BACKGROUND

Survivin has multiple functions during the progression of cancer. However, the role of survivin in the progression and metastasis of hepatocellular carcinoma (HCC) remains unknown.

MATERIALS AND METHODS

Survivin expression in HCC cells (Mahlavu and Hep3B) was assessed using reverse transcription real-time PCR and Western blot analyses. In addition, survivin expression in HCC cells was manipulated using small interfering RNA (siRNA) or overexpression and proliferation and transwell migration assays were performed to monitor the effect of manipulated survivin expression on the growth rate and migratory ability of the transfected cells.

RESULTS

Among the HCC cell lines tested, we found high endogenous expression of survivin mRNA and protein in Mahlavu cells. After silencing survivin expression in Mahlavu cells, there was a dramatic decrease in the cell growth rate and an increase in the metastatic potential of the cells. Overexpression of survivin in Hep3B cells suppressed the ability of the cell to migrate. The mechanism of enhanced cell migration caused by decreased survivin expression is mediated through the downregulation of glucose-regulated protein 78 (GRP78) and the upregulation of the epithelial-mesenchymal transition (EMT) marker, vimentin.

CONCLUSIONS

Survivin may mediate metastasis in HCC. The knockdown of survivin expression may enhance cancer metastasis through the downregulation of GRP78 and upregulation of vimentin expression.

Curcumin enhances the effect of cisplatin in suppression of head and neck squamous cell carcinoma via inhibition of IKKβ protein of the NFκB pathway

Previous experiments have shown that curcumin or cisplatin treatment suppresses growth of head and neck squamous cell carcinoma (HNSCC). To study the potential cooperative effect of both agents, two HNSCC cell lines were treated with curcumin or cisplatin alone or in combination. In vivo studies consisted of intravenous tail vein injection of liposomal curcumin, with intraperitoneal cisplatin, into nude mice growing xenograft HNSCC tumors. Introduction of curcumin and suboptimal concentrations of cisplatin showed a significant suppressive effect compared with treatment with either agent alone. Reduced expression of cyclin D1, IκBα, phospho-IκBα, and IKKβ occurred in cisplatin- and curcumin-treated cell lines. Confocal microscopy showed expression of IKKβ in the nucleus of the cell lines. Chromatin immunoprecipitation assay on DNA isolated from IKKβ immunoprecipitated samples showed PCR amplification of interleukin-8 promoter sequences, a binding site of NFκB, indicating an interaction between IKKβ and NFκB. Curcumin inhibited IKKβ in the cytoplasm and nucleus, leading to reduced NFκB activity, with no effect on phospho-AKT. In vivo studies showed significant growth inhibition of xenograft tumors treated with a combination of liposomal curcumin and cisplatin. The suppressive effect of curcumin was mediated through inhibition of cytoplasmic and nuclear IKKβ, resulting in inhibition of NFκB activity. Cisplatin treatment led to cellular senescence, indicating an effect mediated by p53 activation. The mechanisms of the two agents through different growth signaling pathways suggest potential for the clinical use of subtherapeutic doses of cisplatin in combination with curcumin, which will allow effective suppression of tumor growth while minimizing the toxic side effects of cisplatin.

Substrate-dependent modulation of the catalytic activity of CYP3A by erlotinib

AIM

To ascertain the effects of erlotinib on CYP3A, to investigate the amplitude and kinetics of erlotinib-mediated inhibition of seven major CYP isoforms in human liver microsomes (HLMs) for evaluating the magnitude of erlotinib in drug-drug interaction in vivo.

METHODS

The activities of 7 major CYP isoforms (CYP1A2, CYP2A6, CYP3A, CYP2C9, CYP2D6, CYP2C8, and CYP2E1) were assessed in HLMs using HPLC or UFLC analysis. A two-step incubation method was used to examine the time-dependent inhibition of erlotinib on CYP3A.

RESULTS

The activity of CYP2C8 was inhibited with an IC(50) value of 6.17±2.0 μmol/L. Erlotinib stimulated the midazolam 1'-hydroxy reaction, but inhibited the formation of 6β-hydroxytestosterone and oxidized nifedipine. Inhibition of CYP3A by erlotinib was substrate-dependent: the IC(50) values for inhibiting testosterone 6β-hydroxylation and nifedipine metabolism were 31.3±8.0 and 20.5±5.3 μmol/L, respectively. Erlotinib also exhibited the time-dependent inhibition on CYP3A, regardless of the probe substrate used: the value of K(I) and k(inact) were 6.3 μmol/L and 0.035 min(-1) for midazolam; 9.0 μmol/L and 0.045 min(-1) for testosterone; and 10.1 μmol/L and 0.058 min(-1) for nifedipine.

CONCLUSION

The inhibition of CYP3A by erlotinib was substrate-dependent, while its time-dependent inhibition on CYP3A was substrate-independent. The time-dependent inhibition of CYP3A may be a possible cause of drug-drug interaction, suggesting that attention should be paid to the evaluation of erlotinib's safety, especially in the context of combination therapy.

Antibodies targeting cancer stem cells: a new paradigm in immunotherapy?

Antibody targeting of cancer is showing clinical and commercial success after much intense research and development over the last 30 years. They still have the potential to delivery long-term cures but a shift in thinking towards a cancer stem cell (CSC) model for tumor development is certain to impact on how antibodies are selected and developed, the targets they bind to and the drugs used in combination with them. CSCs have been identified from many human tumors and share many of the characteristics of normal stem cells. The ability to renew, metabolically or physically protect themselves from xenobiotics and DNA damage and the range of locomotory-related receptors expressed could explain the observations of drug resistance and radiation insensitivity leading to metastasis and patient relapse.Targeting CSCs could be a strategy to improve the outcome of cancer therapy but this is not as simple as it seems. Targets such as CD133 and EpCAM/ESA could mark out CSCs from normal cells enabling specific intervention but indirect strategies such as interfering with the establishment of a supportive niche through anti-angiogenic or anti-stroma therapy could be more effective.This review will outline the recent discoveries for CSCs across the major tumor types highlighting the possible molecules for intervention. Examples of antibody-directed CSC therapies and the outlook for the future development of this emerging area will be given.

Combining targeted therapies: practical issues to consider at the bench and bedside

Numerous practical issues must be considered when combining targeted therapies in early clinical drug development. These include tumor resistance mechanisms, the existence of multiple, redundant signaling pathways, and the failure of single-agent therapies to achieve cures. The strategies adopted to examine combinatorial therapy include the goal of hitting more than one target by specifically inhibiting signal transduction cascades and suppressing specific mechanisms of action with the use of multitargeted kinase inhibitors made possible by high-throughput screening techniques, combinatorial chemistry, and chemoinformatics. Two complex considerations are: which agents to combine given the heterogeneity of tumors and their various underlying perturbations, including secondary mutations and feedback loops, and how to translate findings from the bench to the bedside or directly from the bedside. Another consideration is: When is there enough information to provide a rationale for instituting a phase I trial? Various strategies have been used in combining molecules, including targeting diverse pathways, inhibiting upstream and downstream signals, and adopting a synthetic lethality paradigm. Other issues are: determining appropriate target populations for treatment, how to combine therapeutics with diagnostics, and the frequency of targets in patients referred to clinical trials. Here, we review these issues and we propose various novel trial designs that are logical for determining the efficacy of a drug or drug combination for personalized treatment. A difficult issue that must be answered is how many and which drugs to combine. Recent technologies, such as multiplexed assay platforms and bioinformatics, will shape the future of clinical trials and help answer these questions surrounding combinatorial treatment.

The role of transient receptor potential channels in kidney disease

The transient receptor potential (TRP) superfamily consists, in mammals, of six protein subfamilies, TRPC, TRPM, TRPV, TRPA, TRPML and TRPP. TRPs are cation channels involved in many physiological processes and in the pathogenesis of various disorders. In the kidney, TRP channels are expressed along the nephron, and a role for some of these channels in renal function has been proposed. TRPC3 is thought to facilitate calcium ion influx into the principal cells of the collecting duct in response to vasopressin. TRPM3 and TRPV4 might be osmosensors, whereas the TRPP1/TRPP2 complex could function as a mechanosensor in the cilia of renal epithelial cells. A number of kidney diseases have also been linked to dysfunctional activity of TRPs. TRPC6 dysfunction has been associated with the onset of focal segmental glomerosclerosis; TRPP2 dysfunction is linked to autosomal-dominant polycystic kidney disease, TRPM6 mutations underlie hypomagnesemia with secondary hypocalcemia, and TRPV1 dysfunction is implicated in renal hypertension. A link between TRPC1 dysfunction and diabetic nephropathy has also been suggested in an animal model. Animal studies have implicated a role for TRPV5 in idiopathic hypercalciuria and vitamin D-dependent rickets, although these observations have not been confirmed in patients. This Review focuses on the role of renal TRP channels in health and disease.