A recombinant humanized anti-insulin-like growth factor receptor type I antibody (h7C10) enhances the antitumor activity of vinorelbine and anti-epidermal growth factor receptor therapy against human cancer xenografts

Design, synthesis and biological evaluation of 2,3-dihydroimidazo[2,1-b]thiazoles as dual EGFR and IGF1R inhibitors

Herein we describe the design, synthesis and anticancer evaluation of a series of 2,3-dihydroimidazo[2,1-b]thiazoles as dual kinase inhibitors of IGF1R and EGFR. A series of saturated dihydroimidazo[2,1-b] thiazoles were synthesized to understand the structure-activity relationship. Further, the key modifications were performed to improve drug like properties of the series. A 2-oxa-6-azaspiro [3.3] heptane moiety was incorporated as a bioisosteric replacement of morpholine on dihydroimidazo[2,1-b] thiazole scaffold.Subsequent structure-activity relationship (SAR) studies identified several compounds with nM range of activity. The compound 18a shows promising activity, IC₅₀ = 52 nM against IGF1R and IC₅₀ = 35.5 nM against EGFR with descent PK profile. The identified leadshows promising activity against both wild type and the T790M mutant forms of enzymes.

Mechanisms of resistance to chemotherapy in non-small cell lung cancer

Non-small cell lung cancer (NSCLC), which represents 80-85% of lung cancer cases, is one of the leading causes of human death worldwide. The majority of patients undergo an intensive and invasive treatment regimen, which may include radiotherapy, chemotherapy, targeted therapy, immunotherapy, or a combination of these, depending on disease stage and performance status. Despite advances in therapeutic regimens, the 5-year survival of NSCLC is approximately 20-30%, largely due to diagnosis at advanced stages. Conventional chemotherapy is still the standard treatment option for patients with NSCLC, especially those with advanced disease. However, the emergence of resistance to chemotherapeutic agents (chemoresistance) poses a significant obstacle to the management of patients with NSCLC. Therefore, to develop efficacious chemotherapeutic approaches for NSCLC, it is necessary to understand the mechanisms underlying chemoresistance. Several mechanisms are known to mediate chemoresistance. These include altered cellular targets for chemotherapy, decreased cellular drug concentrations, blockade of chemotherapy-induced cell cycle arrest and apoptosis, acquisition of epithelial-mesenchymal transition and cancer stem cell-like phenotypes, deregulated expression of microRNAs, epigenetic modulation, and the interaction with tumor microenvironments. In this review, we summarize the mechanisms underlying chemoresistance and tumor recurrence in NSCLC and discuss potential strategies to avoid or overcome chemoresistance.

Below the Surface: IGF-1R Therapeutic Targeting and Its Endocytic Journey

Ligand-activated plasma membrane receptors follow pathways of endocytosis through the endosomal sorting apparatus. Receptors cluster in clathrin-coated pits that bud inwards and enter the cell as clathrin-coated vesicles. These vesicles travel through the acidic endosome whereby receptors and ligands are sorted to be either recycled or degraded. The traditional paradigm postulated that the endocytosis role lay in signal termination through the removal of the receptor from the cell surface. It is now becoming clear that the internalization process governs more than receptor signal cessation and instead reigns over the entire spatial and temporal wiring of receptor signaling. Governing the localization, the post-translational modifications, and the scaffolding of receptors and downstream signal components established the endosomal platform as the master regulator of receptor function. Confinement of components within or between distinct organelles means that the endosome instructs the cell on how to interpret and translate the signal emanating from any given receptor complex into biological effects. This review explores this emerging paradigm with respect to the cancer-relevant insulin-like growth factor type 1 receptor (IGF-1R) and discusses how this perspective could inform future targeting strategies.

ERBB3 and IGF1R Signaling Are Required for Nrf2-Dependent Growth in KEAP1-Mutant Lung Cancer

Mutations in KEAP1 and NFE2L2 (encoding the protein Nrf2) are prevalent in both adeno and squamous subtypes of non-small cell lung cancer, as well as additional tumor indications. The consequence of these mutations is stabilized Nrf2 and chronic induction of a battery of Nrf2 target genes. We show that knockdown of Nrf2 caused modest growth inhibition of cells growing in two-dimension, which was more pronounced in cell lines expressing mutant KEAP1. In contrast, Nrf2 knockdown caused almost complete regression of established KEAP1-mutant tumors in mice, with little effect on wild-type (WT) KEAP1 tumors. The strong dependency on Nrf2 could be recapitulated in certain anchorage-independent growth environments and was not prevented by excess extracellular glutathione. A CRISPR screen was used to investigate the mechanism(s) underlying this dependence. We identified alternative pathways critical for Nrf2-dependent growth in KEAP1-mutant cell lines, including the redox proteins thioredoxin and peroxiredoxin, as well as the growth factor receptors IGF1R and ERBB3. IGF1R inhibition was effective in KEAP1-mutant cells compared with WT, especially under conditions of anchorage-independent growth. These results point to addiction of KEAP1-mutant tumor cells to Nrf2 and suggest that inhibition of Nrf2 or discrete druggable Nrf2 target genes such as IGF1R could be an effective therapeutic strategy for disabling these tumors. SIGNIFICANCE: This study identifies pathways activated by Nrf2 that are important for the proliferation and tumorigenicity of KEAP1-mutant non-small cell lung cancer.

Blocking ROR1 enhances the roles of erlotinib in lung adenocarcinoma cell lines

Treatment strategies involving tyrosine kinase inhibitors (TKIs) for patients with non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations have advanced significantly; however, challenges still remain regarding the development of resistance. It has been reported that receptor tyrosine kinase-like orphan receptor 1 (ROR1) acts as a hepatocyte growth factor receptor (MET) and c-Src substrate, and that the extracellular domain of ROR1 is associated with EGFR to sustain EGFR-ERBB3-PI3K signaling. Our previous study reported that blocking ROR1 significantly decreased the activity of key signal molecules in the AKT/mammalian target of rapamycin (mTOR) signaling pathway, which was associated with a significant increase of apoptosis and significant decrease of proliferation of lung adenocarcinoma cells. The present study hypothesized that inhibiting ROR1 could potentially prevent erlotinib resistance in NSCLC cell lines. Investigations were performed with two erlotinib-resistant cell lines XLA-07 and NCI-H1975, and an erlotinib-acquired-resistant cell line PC-9erlo, which was developed from its parental cell line PC-9. It was identified that the inhibition of ROR1 via small interfering RNA treatment significantly improved the anti-proliferation and apoptosis-inducing roles of erlotinib in TKI-resistant tumor cells. This was in accordance with the activity of key molecules of the AKT/mTOR signaling pathway, including glycogen synthase kinase-3α/β (GSK-3α/β), phosphatase and tensin homolog (PTEN), AKT, mTOR and ribosomal protein S6 kinase β-1 (p70S6K). The current data suggest that targeting ROR1 is a potential novel treatment strategy for patients with ROR1-positive NSCLC, particularly those with acquired resistance to EGFR-TKI.

Pharmacologic Considerations in the Disposition of Antibodies and Antibody-Drug Conjugates in Preclinical Models and in Patients

The rapid advancement in the development of therapeutic proteins, including monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs), has created a novel mechanism to selectively deliver highly potent cytotoxic agents in the treatment of cancer. These agents provide numerous benefits compared to traditional small molecule drugs, though their clinical use still requires optimization. The pharmacology of mAbs/ADCs is complex and because ADCs are comprised of multiple components, individual agent characteristics and patient variables can affect their disposition. To further improve the clinical use and rational development of these agents, it is imperative to comprehend the complex mechanisms employed by antibody-based agents in traversing numerous biological barriers and how agent/patient factors affect tumor delivery, toxicities, efficacy, and ultimately, biodistribution. This review provides an updated summary of factors known to affect the disposition of mAbs/ADCs in development and in clinical use, as well as how these factors should be considered in the selection and design of preclinical studies of ADC agents in development.

Comparative mRNA and miRNA transcriptome analysis of a mouse model of IGFIR-driven lung cancer

Mouse models of cancer play an important role in elucidating the molecular mechanisms that contribute to tumorigenesis. The extent to which these models resemble one another and their human counterparts at the molecular level is critical in understanding tumorigenesis. In this study, we carried out a comparative gene expression analysis to generate a detailed molecular portrait of a transgenic mouse model of IGFIR-driven lung cancer. IGFIR-driven tumors displayed a strong resemblance with established mouse models of lung adenocarcinoma, particularly EGFR-driven models highlighted by elevated levels of the EGFR ligands Ereg and Areg. Cross-species analysis revealed a shared increase in human lung adenocarcinoma markers including Nkx2.1 and Napsa as well as alterations in a subset of genes with oncogenic and tumor suppressive properties such as Aurka, Ret, Klf4 and Lats2. Integrated miRNA and mRNA analysis in IGFIR-driven tumors identified interaction pairs with roles in ErbB signaling while cross-species analysis revealed coordinated expression of a subset of conserved miRNAs and their targets including miR-21-5p (Reck, Timp3 and Tgfbr3). Overall, these findings support the use of SPC-IGFIR mice as a model of human lung adenocarcinoma and provide a comprehensive knowledge base to dissect the molecular pathogenesis of tumor initiation and progression.

Targeted Therapies Against Growth Factor Signaling in Breast Cancer

Breast cancer is the most prevalent female malignancy throughout the world. Conventional treatment strategies for breast cancer consist of chemotherapy, radiation, surgery, chemoradiation, hormone therapy, and targeted therapies. Among them, targeted therapies show advantages to reduce cost and toxicity for being possible for individualized treatments based on the intrinsic subtypes of breast cancer. With deeper understanding of key signaling pathways concerning tumor growth and survival, growth factor-controlled signaling pathways are frequently dysregulated in the development and progression of breast cancer. Thus, targeted therapies against growth factor-mediated signaling pathways have been shown to have promising efficacy in both preclinical animal models and human clinical trials. In this chapter, we will briefly introduce inhibitors and monoclonal antibodies that target the main growth factor-modulated scenarios including epidermal growth factor receptor (EGFR), transforming growth factor beta (TGF-β), insulin-like growth factor 1 receptor (IGF1R), and fibroblast growth factor receptor (FGFR) signaling pathways in breast cancer therapy.

Randomized, phase I/II study of gemcitabine plus IGF-1R antagonist (MK-0646) versus gemcitabine plus erlotinib with and without MK-0646 for advanced pancreatic adenocarcinoma

BACKGROUND

Binding of insulin-like growth factor-I (IGF-1) to its receptor (IGF-1R) initiates downstream signals that activate PI3K/Akt/mTOR and MEK/Erk pathways, which stimulate cancer cell proliferation and induce drug resistance. Cross talk between IGF-1R and epidermal growth factor receptor (EGFR) mediates resistance to anti-EGFR agents. We studied safety, tolerability, and outcomes of MK-0646, IGF-1 monoclonal antibody, in combination with gemcitabine (G) ± erlotinib (E) in metastatic pancreatic cancer.

METHODS

Our study included a phase I dose escalation and phase II randomization and expansion cohorts. A 3 + 3 dose escalation protocol was used to determine MK-0646 maximum tolerable dose (MTD) in combination with G ± E standard doses. For phase II, patients were randomized to arm A (G + MK), arm B (G + MK + E), or arm C (G + E). Primary endpoint was progression-free survival (PFS). Secondary endpoints were overall survival (OS), disease control rate, toxicity, and correlation between OS and IGF-1 in patients treated with MK-0646.

RESULTS

MK-0646 MTD was 10 mg/kg in combination with G and 5 mg/kg in combination with G + E. In randomization cohort, 15 patients were treated in each arm. Disease control rates were 50, 60, and 40% respectively. PFS was not different between the three arms. OS was significantly different between arm A (10.4 months) and C (5.7 months) (P = 0.02). However, addition of erlotinib in arm B yielded no OS benefit compared to arm A (P = 0.6). Plasma and tissue IGF-1 levels did not correlate with OS (P = 0.64, 0.87). Grade 3-4 toxicity during phase II cohorts were neutropenia (10/arm A, 14/arm B, 5/arm C), leukopenia (5/A, 5/B, 7/C), thrombocytopenia (8/A, 9/B, 2/C), hyponatremia (1/A, 3/B), and hyperglycemia (8/A, 1/B).

CONCLUSIONS

MK-0646 was tolerable in combination with G and associated with improvement in OS but not PFS as compared with G + E. Tissue and serum IGF-1 did not correlate with clinical outcome.

TRIAL REGISTRATION

This trial is registered in ClinicalTrial.gov under the Identifier NCT00769483 and registration date was October 9, 2008.

Phase II randomized trial of carboplatin, paclitaxel, bevacizumab with or without cixutumumab (IMC-A12) in patients with advanced non-squamous, non-small-cell lung cancer: a trial of the ECOG-ACRIN Cancer Research Group (E3508)

Background

Cixutumumab is a fully human IgG1 monoclonal antibody to the insulin-like growth factor type I receptor that can potentially reverse resistance and enhance the efficacy of chemotherapy.

Methods

Bevacizumab-eligible patients with stage IV or recurrent non-squamous, non-small-cell lung cancer and good performance status were randomized to receive standard doses of paclitaxel, carboplatin, and bevacizumab to a maximum of six cycles followed by bevacizumab maintenance (CPB) until progression (arm A) or CPB plus cixutumumab 6 mg/kg i.v. weekly (arm B).

Results

Of 175 patients randomized, 153 were eligible and treated (78 in arm A; 75 in arm B). The median progression-free survival was 5.8 months (95% CI 5.4-7.1) in arm A versus 7 months (95% CI 5.7-7.6) in arm B (P = 0.33); hazard ratio 0.92 (95% CI 0.65-1.31). Objective response was 46.2% versus 58.7% in arm A versus arm B (P = 0.15). The median overall survival was 16.2 months in arm A versus 16.1 months in arm B (P = 0.95). Grade 3/4 neutropenia and febrile neutropenia, thrombocytopenia, fatigue, and hyperglycemia were increased with cixutumumab.

Conclusions

The addition of cixutumumab to CPB increased toxicity without improving efficacy and is not recommended for further development in non-small-cell lung cancer. Both treatment groups had longer OS than historical controls which may be attributed to several factors, and emphasizes the value of a comparator arm in phase II trials.

ClinicalTrials.gov Identifier

NCT00955305.

Expressions of insulin-like growth factor receptor-1 and cezanne-1 in lung adenocarcinoma

IGF1R (insulin-like growth factor receptor-1) was confirmed to play a significant role in the development of cancer. Cezanne-1 overexpression was considered to be associated with enhancement of EGFR signaling pathway and reduced degeneration of EGFR. There was a close relationship between EGFR and IGFR as previous study showed. Dynamic balance between receptor ubiquitination and deubiquitination was critical in the process of termination of IGF signaling pathway. So we conducted an IHC staining to initially prove the correlation. Cezanne-1 and IGF1R expressions were evaluated in 103 patients with lung adenocarcinoma using immunohistochemical (IHC) analysis. The relationship between expressions of cezanne-1 and IGF1R were analyzed by χ2 test. Kaplan-Meier method was used to generate the survival curve, and the statistical difference was calculated by log-rank test. We also used data in R2 system to verify the relationship between IGF1R and cezanne-1. R2 system showed there was a close correlation between IGF1R and cezanne-1. Positive expression of cezanne-1 was detected in 64.1% patients. A significant association was shown between cezanne-1 and IGF1R expression (p < 0.001). Multivariate analysis confirmed that both cezanne-1 and IGF1R expressions were independent prognostic factors for OS. (HR 2.96, 95% CI 1.090-8.060, p = 0.033; HR 2.273, 95% CI 1.016-5.085, p = 0.046, respectively). Our findings indicated both cezanne-1 and IGF1R expressions were negative independent predictive factors for the prognosis of lung adenocarcinoma, respectively. There was a close positive interrelationship between cezanne-1 and IGF1R expression.

Unique roles of Akt1 and Akt2 in IGF-IR mediated lung tumorigenesis

AKT is a serine-threonine kinase that becomes hyperactivated in a number of cancers including lung cancer. Based on AKT's association with malignancy, molecules targeting AKT have entered clinical trials for solid tumors including lung cancer. However, the AKT inhibitors being evaluated in clinical trials indiscriminately inhibit all three AKT isoforms (AKT1-3) and it remains unclear whether AKT isoforms have overlapping or divergent functions. Using a transgenic mouse model where IGF-IR overexpression drives lung tumorigenesis, we found that loss of Akt1 inhibited while loss of Akt2 enhanced lung tumor development. Lung tumors that developed in the absence of Akt2 were less likely to appear as discrete nodules and more frequently displayed a dispersed growth pattern. RNA sequencing revealed a number of genes differentially expressed in lung tumors lacking Akt2 and five of these genes, Actc1, Bpifa1, Mmp2, Ntrk2, and Scgb3a2 have been implicated in human lung cancer. Using 2 human lung cancer cell lines, we observed that a selective AKT1 inhibitor, A-674563, was a more potent regulator of cell survival than the pan-AKT inhibitor, MK-2206. This study suggests that compounds selectively targeting AKT1 may prove more effective than compounds that inhibit all three AKT isoforms at least in the treatment of lung adenocarcinoma.

Combination therapy approaches to target insulin-like growth factor receptor signaling in breast cancer

Insulin-like growth factor receptor (IGF1R) signaling as a therapeutic target has been widely studied and clinically tested. Despite the vast amount of literature supporting the biological role of IGF1R in breast cancer, effective clinical translation in targeting its activity as a cancer therapy has not been successful. The intrinsic complexity of cancer cell signaling mediated by many tyrosine kinase growth factor receptors that work together to modulate each other and intracellular downstream mediators in the cell highlights that studying IGF1R expression and activity as a prognostic factor and therapeutic target in isolation is certainly associated with problems. This review discusses the current literature and clinical trials associated with IGF-1 signaling and attempts to look at new ways of designing novel IGF1R-directed breast cancer therapy approaches to target its activity 
and/or intracellular downstream signaling pathways in IGF1R-expressing breast cancers.

Clinical studies in humans targeting the various components of the IGF system show lack of efficacy in the treatment of cancer

The insulin-like growth factors (IGFs) system regulates cell growth, differentiation and energy metabolism and plays crucial role in the regulation of key aspects of tumor biology, such as cancer cell growth, survival, transformation and invasion. The current focus for cancer therapeutic approaches have shifted from the conventional treatments towards the targeted therapies and the IGF system has gained a great interest as anti-cancer therapy. The proliferative, anti-apoptotic and transformation effects of IGFs are mainly triggered by the ligation of the type I IGF receptor (IGF-IR). Thus, aiming at developing novel and effective cancer therapies, different strategies have been employed to target IGF system in human malignancies, including but not limited to ligand or receptor neutralizing antibodies and IGF-IR signaling inhibitors. In this review, we have focused on the clinical studies that have been conducted targeting the various components of the IGF system for the treatment of different types of cancer, providing a description and the challenges of each targeting strategy and the degree of success.

Optical imaging probes in oncology

Cancer is a complex disease, characterized by alteration of different physiological molecular processes and cellular features. Keeping this in mind, the possibility of early identification and detection of specific tumor biomarkers by non-invasive approaches could improve early diagnosis and patient management.Different molecular imaging procedures provide powerful tools for detection and non-invasive characterization of oncological lesions. Clinical studies are mainly based on the use of computed tomography, nuclear-based imaging techniques and magnetic resonance imaging. Preclinical imaging in small animal models entails the use of dedicated instruments, and beyond the already cited imaging techniques, it includes also optical imaging studies. Optical imaging strategies are based on the use of luminescent or fluorescent reporter genes or injectable fluorescent or luminescent probes that provide the possibility to study tumor features even by means of fluorescence and luminescence imaging. Currently, most of these probes are used only in animal models, but the possibility of applying some of them also in the clinics is under evaluation.The importance of tumor imaging, the ease of use of optical imaging instruments, the commercial availability of a wide range of probes as well as the continuous description of newly developed probes, demonstrate the significance of these applications. The aim of this review is providing a complete description of the possible optical imaging procedures available for the non-invasive assessment of tumor features in oncological murine models. In particular, the characteristics of both commercially available and newly developed probes will be outlined and discussed.

Implications of Insulin-like Growth Factor 1 Receptor Activation in Lung Cancer

Insulin-like growth factor 1 receptor (IGF1R) has been intensively investigated in many preclinical studies using cell lines and animal models, and the results have provided important knowledge to help improve the understanding of cancer biology. IGF1R is highly expressed in patients with lung cancer, and high levels of circulating insulin-like growth factor 1 (IGF1), the main ligand for IGF1R, increases the risk of developing lung malignancy in the future. Several phase I clinical trials have supported the potential use of an IGF1R-targeted strategy for cancer, including lung cancer. However, the negative results from phase III studies need further attention, especially in selecting patients with specific molecular signatures, who will gain benefits from IGF1R inhibitors with minimal side effects. This review will discuss the basic concept of IGF1R in lung cancer biology, such as epithelial-mesenchymal transition (EMT) induction and cancer stem cell (CSC) maintenance, and also the clinical implications of IGF1R for lung cancer patients, such as prognostic value and cancer therapy resistance.

XGFR*, a novel affinity-matured bispecific antibody targeting IGF-1R and EGFR with combined signaling inhibition and enhanced immune activation for the treatment of pancreatic cancer

The epidermal growth factor receptor (EGFR) and the insulin-like growth factor-1 receptor (IGF-1R) play critical roles in tumor growth, providing a strong rationale for the combined inhibition of IGF-1R and EGFR signaling in cancer therapy. We describe the design, affinity maturation, in vitro and in vivo characterization of the bispecific anti-IGF-1R/EGFR antibody XGFR*. XGFR* is based on the bispecific IgG antibody XGFR, which enabled heterodimerization of an IGF-1R binding scFab heavy chain with an EGFR-binding light and heavy chain by the "knobs-into-holes" technology. XGFR* is optimized for monovalent binding of human EGFR and IGF-1R with increased binding affinity for IGF-1R due to affinity maturation and highly improved protein stability to oxidative and thermal stress. It bears an afucosylated Fc-portion for optimal induction of antibody-dependent cell-mediated cytotoxicity (ADCC). Stable Chinese hamster ovary cell clones with production yields of 2-3 g/L were generated, allowing for large scale production of the bispecific antibody. XGFR* potently inhibits EGFR- and IGF-1R-dependent receptor phosphorylation, reduces tumor cell proliferation in cells with heterogeneous levels of IGF-1R and EGFR receptor expression and induces strong ADCC in vitro. A comparison of pancreatic and colorectal cancer lines demonstrated superior responsiveness to XGFR*-mediated signaling and tumor growth inhibition in pancreatic cancers that frequently show a high degree of IGF-1R/EGFR co-expression. XGFR* showed potent anti-tumoral efficacy in the orthotopic MiaPaCa-2 pancreatic xenograft model, resulting in nearly complete tumor growth inhibition with significant number of tumor remissions. In summary, the bispecific anti-IGF-1R/EGFR antibody XGFR* combines potent signaling and tumor growth inhibition with enhanced ADCC induction and represents a clinical development candidate for the treatment of pancreatic cancer.

Novel agents for advanced pancreatic cancer

Pancreatic cancer is relatively insensitive to conventional chemotherapy. Therefore, novel agents targeting dysregulated pathways (MAPK/ERK, EGFR, TGF-β, HEDGEHOG, NOTCH, IGF, PARP, PI3K/AKT, RAS, and Src) are being explored in clinical trials as monotherapy or in combination with cytotoxic chemotherapy. This review summarizes the most recent advances with the targeted therapies in the treatment of patients with advanced pancreatic cancer.

Mechanisms of action of therapeutic antibodies for cancer

The therapeutic utility of antibodies and their derivatives is achieved by various means. The FDA has approved several targeted antibodies that disrupt signaling of various growth factor receptors for the treatment of a number of cancers. Rituximab, and other anti-CD20 monoclonal antibodies are active in B cell malignancies. As more experience has been gained with anti-CD20 monoclonal antibodies, the multifactorial nature of their anti-tumor mechanisms has emerged. Other targeted antibodies function to dampen inhibitory checkpoints. These checkpoint inhibitors have recently achieved dramatic results in several cancers, including melanoma. These and related antibodies continue to be investigated in the clinical and pre-clinical settings. Novel antibody structures that target two or more antigens have also made their way into clinical use. Tumor targeted antibodies can also be conjugated to chemo- or radiotherapeutic agents, or catalytic toxins, as a means to deliver toxic payloads to cancer cells. Here we provide a review of these mechanisms and a discussion of their relevance to current and future clinical applications.

Three-arm, randomized, phase 2 study of carboplatin and paclitaxel in combination with cetuximab, cixutumumab, or both for advanced non-small cell lung cancer (NSCLC) patients who will not receive bevacizumab-based therapy: An Eastern Cooperative Oncology Group (ECOG) study (E4508)

BACKGROUND

Preclinical evidence supports the clinical investigation of inhibitors to the insulin-like growth factor receptor (IGFR) and the epidermal growth factor receptor (EGFR) either alone or in combination as treatment for patients with non-small cell lung cancer (NSCLC).

METHODS

Patients with chemotherapy-naïve, advanced NSCLC who had an Eastern Cooperative Oncology Group performance status of 0 or 1 were eligible. Patients were randomized to receive carboplatin intravenously at an area under the plasma drug concentration-time curve of 6.0 plus paclitaxel 200 mg/m(2) intravenously on day 1 every 3 weeks combined with either intravenous cetuximab weekly (arm A), intravenous cixutumumab every 2 weeks (arm B), or both (arm C). Patients who had nonprogessing disease after 12 weeks of therapy were permitted to continue on maintenance antibody therapy until they developed progressive disease. The primary endpoint was progression-free survival (PFS). The study design required 180 eligible patients and had 88% power to detect a 60% increase in median PFS for either comparison (arm A vs arm C or arm B vs arm C) using the log-rank test.

RESULTS

From September 2009 to December 2010, 140 patients were accrued. The study was closed to accrual early because of an excessive number of grade 5 events reported on arms A and C. Thirteen patients died during treatment (6 patients on arm A, 2 patients on arm B, and 5 patients on arm C), including 9 within approximately 1 month of starting therapy. The estimated median PFS for arms A, B, and C were similar at 3.4 months, 4.2 months, and 4 months, respectively.

CONCLUSIONS

On the basis of the apparent lack of efficacy and excessive premature deaths, the current results do not support the continued investigation of carboplatin, paclitaxel, and cixutumumab either alone or in combination with cetuximab for patients with advanced NSCLC.

Picropodophyllin causes mitotic arrest and catastrophe by depolymerizing microtubules via insulin-like growth factor-1 receptor-independent mechanism

Picropodophyllin (PPP) is an anticancer drug undergoing clinical development in NSCLC. PPP has been shown to suppress IGF-1R signaling and to induce a G2/M cell cycle phase arrest but the exact mechanisms remain to be elucidated. The present study identified an IGF-1-independent mechanism of PPP leading to pro-metaphase arrest. The mitotic block was induced in human cancer cell lines and in an A549 xenograft mouse but did not occur in normal hepatocytes/mouse tissues. Cell cycle arrest by PPP occurred in vitro and in vivo accompanied by prominent CDK1 activation, and was IGF-1R-independent since it occurred also in IGF-1R-depleted and null cells. The tumor cells were not arrested in G2/M but in mitosis. Centrosome separation was prevented during mitotic entry, resulting in a monopolar mitotic spindle with subsequent prometaphase-arrest, independent of Plk1/Aurora A or Eg5, and leading to cell features of mitotic catastrophe. PPP also increased soluble tubulin and decreased spindle-associated tubulin within minutes, indicating that it interfered with microtubule dynamics. These results provide a novel IGF-1R-independent mechanism of antitumor effects of PPP.

Randomized, phase III trial of figitumumab in combination with erlotinib versus erlotinib alone in patients with nonadenocarcinoma nonsmall-cell lung cancer

BACKGROUND

Figitumumab (CP-751,871) is a fully human IgG2 monoclonal antibody that inhibits the insulin-like growth factor 1 receptor. This multicenter, randomized, phase III study investigated the efficacy of figitumumab plus erlotinib compared with erlotinib alone in patients with pretreated, nonsmall-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients (stage IIIB/IV or recurrent disease with nonadenocarcinoma histology) who had previously received at least one platinum-based regimen were randomized to receive open-label figitumumab (20 mg/kg) plus erlotinib 150 mg/day or erlotinib alone every 3 weeks. The primary end point was overall survival (OS).

RESULTS

Of 583 patients randomized, 579 received treatment. The study was closed early by an independent data safety monitoring committee due to results crossing the prespecified futility boundary. At the final analysis, median OS was 5.7 months for figitumumab plus erlotinib and 6.2 months for erlotinib alone [hazard ratio (HR) 1.09; 95% confidence interval (CI) 0.91-1.31; P = 0.35]. Median progression-free survival was 2.1 months for figitumumab plus erlotinib and 2.6 months for erlotinib alone (HR 1.08; 95% CI 0.90-1.29; P = 0.43). Treatment-related nonfatal serious adverse events occurred in 18% and 5% of patients in the figitumumab arm or erlotinib alone arm, respectively. There were nine treatment-related deaths (three related to both drugs, four related to erlotinib alone and two related to figitumumab).

CONCLUSIONS

The addition of figitumumab to erlotinib did not improve OS in patients with advanced, pretreated, nonadenocarcinoma NSCLC. Clinical development of figitumumab has been discontinued.

CLINICAL TRIAL ID

NCT00673049.

A novel glycoengineered bispecific antibody format for targeted inhibition of epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor type I (IGF-1R) demonstrating unique molecular properties

In the present study, we have developed a novel one-arm single chain Fab heterodimeric bispecific IgG (OAscFab-IgG) antibody format targeting the insulin-like growth factor receptor type I (IGF-1R) and the epidermal growth factor receptor (EGFR) with one binding site for each target antigen. The bispecific antibody XGFR is based on the "knob-into-hole" technology for heavy chain heterodimerization with one heavy chain consisting of a single chain Fab to prevent wrong pairing of light chains. XGFR was produced with high expression yields and showed simultaneous binding to IGF-1R and EGFR with high affinity. Due to monovalent binding of XGFR to IGF-1R, IGF-1R internalization was strongly reduced compared with the bivalent parental antibody, leading to enhanced Fc-mediated cellular cytotoxicity. To further increase immune effector functions triggered by XGFR, the Fc portion of the bispecific antibody was glycoengineered, which resulted in strong antibody-dependent cell-mediated cytotoxicity activity. XGFR-mediated inhibition of IGF-1R and EGFR phosphorylation as well as A549 tumor cell proliferation was highly effective and was comparable with a combined treatment with EGFR (GA201) and IGF-1R (R1507) antibodies. XGFR also demonstrated potent anti-tumor efficacy in multiple mouse xenograft tumor models with a complete growth inhibition of AsPC1 human pancreatic tumors and improved survival of SCID beige mice carrying A549 human lung tumors compared with treatment with antibodies targeting either IGF-1R or EGFR. In summary, we have applied rational antibody engineering technology to develop a heterodimeric OAscFab-IgG bispecific antibody, which combines potent signaling inhibition with antibody-dependent cell-mediated cytotoxicity induction and results in superior molecular properties over two established tetravalent bispecific formats.

Anticancer activity of the type I insulin-like growth factor receptor antagonist, ganitumab, in combination with the death receptor 5 agonist, conatumumab

Agents targeting the insulin-like growth factor receptor type 1 (IGF1R) have shown antitumor activity. Based on the evidence for interaction between the IGF-1 and TRAIL pathways, we hypothesized that the combination of ganitumab (monoclonal antibody to IGF1R) with the pro-apoptotic death receptor 5 agonist, conatumumab, might increase antitumor response. Ganitumab and conatumumab were tested in combination in a Colo-205 xenograft model. Part 1 of the clinical study was a phase Ib program of three doses of conatumumab (1, 3, 15 mg/kg) in combination with 18 mg/kg ganitumab to determine the maximum tolerated dose (MTD) in patients with advanced solid tumors. Part 2 was conducted in six cohorts with advanced non-small cell lung cancer (squamous or non-squamous histology), colorectal cancer, sarcoma, pancreatic cancer, or ovarian cancer, treated at the recommended doses of the combination. The combination was significantly more active in the Colo-205 xenograft model than either single agent alone (p < 0.0015). In part 1 of the clinical study, no dose-limiting toxicities were observed and the MTD of conatumumab was 15 mg/kg in combination with 18 mg/kg ganitumab. In part 2, 78 patients were treated and there were no objective responses but 28 patients (36 %) had stable disease (median 46 days, range 0-261). The combination was well-tolerated with no new toxicities. In conclusion, the combination of ganitumab and conatumumab was well-tolerated but had no objective responses in the population tested. The successful future application of this combination of antitumor mechanisms may rely on the identification of predictive biomarkers.

Phase 1b study of safety, tolerability and efficacy of R1507, a monoclonal antibody to IGF-1R in combination with multiple standard oncology regimens in patients with advanced solid malignancies

BACKGROUND

R1507 is a human IgG1 Mab that binds to the insulin-like growth factor-1 receptor (IGF-1R) and inhibits IGF-1- or IGF-2-mediated anchorage-independent growth of malignant cells. A phase 1b study evaluated the safety, tolerability and efficacy of R1507 in combination with multiple standard oncology regimens.

METHODS

R1507 (3, 5, 9, 10 and 16 mg/kg IV, Q2 W or Q3 W) was added to six treatment regimens: gemcitabine + erlotinib (GE); paclitaxel + bevacizumab (PB); carboplatin + etoposide (CE); mFOLFOX6 + bevacizumab (FB); capecitabine + trastuzumab (CT); and sorafenib (S). If tolerable, R1507 dose was escalated utilizing a 3 + 3 + 6 and a 3 + 9 design.

RESULTS

A total of 104 patients enrolled into regimens 1-6: 93 % were non-recent diagnoses. Eighteen withdrew for safety [one death, 17 adverse events (AEs)]. A total of 1,337 AEs any grade, across regimens and doses were nausea, vomiting and diarrhea. A total of 123 had grade ≥3 AEs (n = 28 dose level 1; n = 95 dose level 1) and in 60 patients were myelosuppression, fatigue and mucosal inflammation. ORR (PR plus SD) of evaluable patients across six regimens was 36 % with five PRs: regimens PB (non-small cell lung cancer, nasopharyngeal cancer), CE (melanoma), FB (colon cancer) and S (GIST). The GIST pt (>4 prior therapies) had a PR for 3 years. Three patients (breast cancer, melanoma and adenoid cystic carcinoma) were on study for >1 year; 76 % of patients had SD or better for 4 months.

CONCLUSIONS

R1507 added to six standard oncology regimens was well tolerated with an ORR of 36 %.

[Recent update of molecular targeted therapy in pancreatic cancer]

Pancreatic ductal adenocarcinoma is one of the most dreaded malignancies and the 5th leading cause of cancer-related death in Korea. Late diagnosis and unfavorable response to both chemotherapy and radiotherapy result in exceptionally poor prognosis. Recently, the rapid advances of molecular biology allowed an in-depth understanding of pancreatic carcinogenesis, and there are many attempts to modulate signal pathway using specific targeted agent. However, the most of them have so far failed to improve survival significantly except erlotinib. The real challenge is now how these impressive advances of molecular biology could be successfully integrated into better clinical implications. Herein, we summarize the latest insights into the carcinogenesis, and their repercussions for novel targeted agents for pancreatic cancer, and provide a review of recent clinical trials using molecular targeted therapy.

Inhaled gene therapy in lung cancer: proof-of-concept for nano-oncology and nanobiotechnology in the management of lung cancer

Lung cancer still remains one of the leading causes of death among cancer patients. Although novel targeted therapies have been established in everyday treatment practice, and conventional platinum-based doublets have demonstrated effective results regarding overall and progression-free survival, we have still failed to achieve long-term survival. Therefore, several strategies of applying locoregional therapy are under investigation. Aerosol chemotherapy is already under investigation and, taking this a step further, aerosol gene therapies with multiple delivery systems are being developed. Several efforts have demonstrated its efficiency and effectiveness, but there are still multiple factors that have to be considered and combined to achieve an overall more effective multifunctional treatment. In the current review, we present data regarding aerosol delivery systems, transporters, carriers, vectors, genes, toxicity, efficiency, specificity, lung microenvironment and delivery gene therapy systems. Finally, we present current studies and future perspectives.

In vivo analysis of insulin-like growth factor type 1 receptor humanized monoclonal antibody MK-0646 and small molecule kinase inhibitor OSI-906 in colorectal cancer

The development and characterization of effective anticancer drugs against colorectal cancer (CRC) is of urgent need since it is the second most common cause of cancer death. The study was designed to evaluate the effects of two IGF-1R antagonists, MK-0646, a recombinant fully humanized monoclonal antibody and OSI-906, a small molecule tyrosine kinase inhibitor on CRC cells. Xenograft study was performed on IGF-1R-dependent CRC cell lines for analyzing the antitumor activity of MK-0646 and OSI-906. Tumor proliferation and apoptosis were assessed using Ki67 and TUNEL assays, respectively. We also performed in vitro characterization of MK-0646 and OSI-906 treatment on CRC cells to identify mechanisms associated with drug-induced cell death. Exposure of the GEO and CBS tumor xenografts to MK-0646 or OSI-906 led to a decrease in tumor growth. TUNEL analysis showed an increase of approximately 45-55% in apoptotic cells in both MK-0646 and OSI-906 treated tumor samples. We report the novel finding that treatment with IGF-1R antagonists led to downregulation of X-linked inhibitor of apoptosis (XIAP) protein involved in cell survival and inhibition of cell death. In conclusion, IGF-1R antagonists (MK-0646 and OSI-906) demonstrated single agent inhibition of subcutaneous CRC xenograft growth. This was coupled to pro-apoptotic effects resulting in downregulation of XIAP and inhibition of cell survival. We report a novel mechanism by which MK-0646 and OSI-906 elicits cell death in vivo and in vitro. Moreover, these results indicate that MK-0646 and OSI-906 may be potential anticancer candidates for the treatment of patients with IGF-1R-dependent CRC.

Phase 1 pharmacokinetic study of MK-0646 (dalotuzumab), an anti-insulin-like growth factor-1 receptor monoclonal antibody, in combination with cetuximab and irinotecan in Japanese patients with advanced colorectal cancer

PURPOSE

The safety, tolerability, and pharmacokinetic (PK) interactions of MK-0646 in combination with cetuximab and irinotecan were investigated in Japanese patients with advanced colorectal cancer.

METHODS

Twenty patients were treated in the following study arms in combination with cetuximab and irinotecan: A [MK-0646 (10 mg/kg) weekly starting on Day 22], B [MK-0646 (15 mg/kg) on Day 8, followed by 7.5 mg/kg every 2 weeks], or C [MK-0646 (10 mg/kg) on Day 1 and weekly starting on Day 22]. Dose limiting toxicities (DLTs) were evaluated during a prespecified 4-week period in arms A and B. Full PK sampling was performed to evaluate the PK interactions.

RESULTS

One of the 6 evaluable patients in arm A developed a DLT (grade 3 hyperglycemia); no DLTs occurred in the 6 patients in arm B. Common treatment-related adverse events included leukopenia, neutropenia, dermatitis acneiform, paronychia, nausea, stomatitis, diarrhea, and decreased appetite. The co-administration of cetuximab and irinotecan with MK-0646 increased the MK-0646 AUC0-168h by 25 %, with MK-0646 accumulation from the previous dose contributing to the observed increase. The co-administration of MK-0646 with cetuximab and irinotecan did not affect the PK of cetuximab and irinotecan, but reduced the C max (from 16.8 to 13.0 ng/mL) and the AUC0-24h (by 13 %) of SN-38, the active metabolite of irinotecan.

CONCLUSIONS

The triple combination of MK-0646, cetuximab, and irinotecan was well tolerated in Japanese patients with advanced colorectal cancer. These results indicate a minimal potential for PK interactions between MK-0646 and cetuximab and between MK-0646 and irinotecan/SN-38.

Potentiating the efficacy of molecular targeted therapy for hepatocellular carcinoma by inhibiting the insulin-like growth factor pathway

Insulin-like growth factor (IGF) signaling pathway is an important regulatory mechanism of tumorigenesis and drug resistance in many cancers. The present study explored the potential synergistic effects between IGF receptor (IGFR) inhibition and other molecular targeted agents (MTA) in HCC cells. HCC cell lines (Hep3B, PLC5, and SK-Hep1) and HUVECs were tested. The MTA tested included sorafenib, sunitinib, and the IGFR kinase inhibitor NVP-AEW541. The potential synergistic antitumor effects were tested by median dose effect analysis and apoptosis assay in vitro and by xenograft models in vivo. The activity and functional significance of pertinent signaling pathways and expression of apoptosis-related proteins were measured by RNA interference and Western blotting. We found that IGF can activate IGFR and downstream AKT signaling activities in all the HCC cells tested, but the growth-stimulating effect of IGF was most prominent in Hep3B cells. NVP-AEW541 can abrogate IGF-induced activation of IGFR and AKT signaling in HCC cells. IGF can increase the resistance of HCC cells to sunitinib. The apoptosis-inducing effects of sunitinib, but not sorafenib, were enhanced when IGFR signaling activity was inhibited by NVP-AEW541 or IGFR knockdown. Chk2 kinase activation was found contributory to the synergistic anti-tumor effects between sunitinib and IGFR inhibition. Our data indicate that the apoptosis-potentiating effects of IGFR inhibition for HCC may be drug-specific. Combination therapy of IGFR inhibitors with other MTA may improve the therapeutic efficacy in HCC.

miR-223 functions as a potent tumor suppressor of the Lewis lung carcinoma cell line by targeting insulin-like growth factor-1 receptor and cyclin-dependent kinase 2

microRNAs (miRNAs) have been hypothesized to function as oncogenes or tumor suppressors by targeting specific cancer-related genes. Previous studies have reported that miR-223 may serve as a tumor suppressor in a number of cancer types, however, knowledge of its targets in non-small cell lung cancer (NSCLC) remains limited. In the current study, miR-223 was found to inhibit cell proliferation in vitro by CCK-8 assay, growth curves and an anchorage-independent growth assay in a Lewis lung carcinoma (LLC) cell line. miR-223 transfection in the LLC cells was observed to significantly inhibit migration and invasion, induce G₂/M arrest and decrease the expression levels of Sca-1, a marker of murine stem cells. In addition, miR-223 transfection markedly suppressed AKT and ERK signaling, as well as insulin-like growth factor-1 receptor (IGF-1R)-mediated downstream signaling, pathways that are crucial for cell proliferation and invasion in NSCLC cells. Analyses in C57BL/6 mice demonstrated that miR-223 suppresses tumorigenicity in vivo. Using a luciferase activity assay and western blot analysis, IGF-1R and cyclin-dependent kinase 2 (CDK2) were identified as direct targets of miR-223. In the present study, novel cancer-related targets of miR-223 were identified and verified in a LLC cell line, indicating that miR-223 functions as a tumor suppressor, which may fine-tune the activity of the IGF-1R pathway in lung cancer. Therefore, increasing miR-223 expression may provide a novel approach for the treatment of NSCLC.

Modulation of insulin-like growth factor-1 receptor and its signaling network for the treatment of cancer: current status and future perspectives

Based on over three decades of pre-clinical data, insulin-like growth factor-1 receptor (IGF-1R) signaling has gained recognition as a promoter of tumorogenesis, driving cell survival and proliferation in multiple human cancers. As a result, IGF-1R has been pursued as a target for cancer treatment. Early pioneering efforts targeting IGF-1R focused on highly selective monoclonal antibodies, with multiple agents advancing to clinical trials. However, despite some initial promising results, recent clinical disclosures have been less encouraging. Moreover, recent studies have revealed that IGF-1R participates in a dynamic and complex signaling network, interacting with additional targets and pathways thereof through various crosstalk and compensatory signaling mechanisms. Such mechanisms of bypass signaling help to shed some light on the decreased effectiveness of selective IGF-1R targeted therapies (e.g. monoclonal antibodies) and suggest that targeting multiple nodes within this signaling network might be necessary to produce a more effective therapeutic response. Additionally, such findings have led to the development of small molecule IGF-1R inhibitors which also co-inhibit additional targets such as insulin receptor and epidermal growth factor receptor. Such findings have helped to guide the design rationale of numerous drug combinations that are currently being evaluated in clinical trials.

Targeting the insulin-like growth factor-1 receptor in human cancer

The insulin-like growth factor (IGF) signaling system plays a crucial role in human cancer and the IGF-1 receptor (IGF-1R) is an attractive drug target against which a variety of novel anti-tumor agents are being developed. Deregulation of the IGF signaling pathway frequently occurs in human cancer and involves the establishment of autocrine loops comprising IGF-1 or IGF-2 and/or IGF-1R over-expression. Epidemiologic studies have documented a link between elevated IGF levels and the development of solid tumors, such as breast, colon, and prostate cancer. Anti-cancer strategies targeting the IGF signaling system involve two main approaches, namely neutralizing antibodies and small molecule inhibitors of the IGF-1R kinase activity. There are numerous reports describing anti-tumor activity of these agents in pre-clinical models of major human cancers. In addition, multiple clinical trials have started to evaluate the safety and efficacy of selected IGF-1R inhibitors, in combination with standard chemotherapeutic regimens or other targeted agents in cancer patients. In this mini review, I will discuss the role of the IGF signaling system in human cancer and the main strategies which have been so far evaluated to target the IGF-1R.

8(th) Annual European Antibody Congress 2012: November 27-28, 2012, Geneva, Switzerland

The 8th European Antibody Congress (EAC), organized by Terrapin Ltd., was again held in Geneva, Switzerland, following on the tradition established with the 4th EAC. The new agenda format for 2012 included three parallel tracks on: (1) naked antibodies; (2) antibody drug conjugates (ADCs); and (3) bispecific antibodies and alternative scaffolds. The meeting started and closed with three plenary lectures to give common background and to share the final panel discussion and conclusions. The two day event included case studies and networking for nearly 250 delegates who learned of the latest advances and trends in the global development of antibody-based therapeutics.

The monoclonal antibody track was focused on understanding the structure-function relationships, optimization of antibody design and developability, and processes that allow better therapeutic candidates to move through the clinic. Discussions on novel target identification and validation were also included. The ADC track was dedicated to evaluation of the ongoing success of the established ADC formats alongside the rise of the next generation drug-conjugates. The bispecific and alternative scaffold track was focused on taking stock of the multitude of bispecific formats being investigated and gaining insight into recent innovations and advancements. Mechanistic understanding, progression into the clinic and the exploration of multispecifics, redirected T cell killing and alternative scaffolds were extensively discussed. In total, nearly 50 speakers provided updates of programs related to antibody research and development on-going in the academic, government and commercial sectors.

The epidemiology and molecular mechanisms linking obesity, diabetes, and cancer

The worldwide epidemic of obesity is associated with increasing rates of the metabolic syndrome and type 2 diabetes. Epidemiological studies have reported that these conditions are linked to increased rates of cancer incidence and mortality. Obesity, particularly abdominal obesity, is associated with insulin resistance and the development of dyslipidemia, hyperglycemia, and ultimately type 2 diabetes. Although many metabolic abnormalities occur with obesity and type 2 diabetes, insulin resistance and hyperinsulinemia appear to be central to these conditions and may contribute to dyslipidemia and altered levels of circulating estrogens and androgens. In this review, we will discuss the epidemiological and molecular links between obesity, type 2 diabetes, and cancer, and how hyperinsulinemia and dyslipidemia may contribute to cancer development. We will discuss how these metabolic abnormalities may interact with estrogen signaling in breast cancer growth. Finally, we will discuss the effects of type 2 diabetes medications on cancer risk.

Deciphering the role of insulin-like growth factor-I receptor in trastuzumab resistance

Resistance to the HER2-targeted antibody trastuzumab is a major clinical concern in the treatment of HER2-overexpressing metastatic breast cancer. Increased expression or signaling of the insulin-like growth factor-I receptor (IGF-IR) has been reported in a subset of cell lines and clinical samples derived from trastuzumab-resistant breast cancers. Genetic and pharmacologic inhibition of IGF-IR signaling has been shown to improve response to trastuzumab in trastuzumab-naïve and trastuzumab-resistant models. In this paper, we will discuss the role of IGF-IR signaling in trastuzumab resistance. Further, we will discuss cotargeting IGF-IR and HER2 as a potential therapeutic strategy for HER2-over-expressing breast cancers that have progressed on trastuzumab treatment.

Acquired resistance to tamoxifen is associated with loss of the type I insulin-like growth factor receptor: implications for breast cancer treatment

The role of the insulin-like growth factor (IGF) system in breast cancer is well defined, and inhibitors of this pathway are currently in clinical trials. The majority of anti-IGF1R clinical trials are in estrogen receptor-positive patients who have progressed on prior endocrine therapy; early reports show no benefit for addition of IGF1R inhibitors to endocrine therapy in this setting. In this study, we examined the effectiveness of IGF1R inhibitors in vitro by generating tamoxifen-resistant (TamR) cells. We found that TamR cells had diminished levels of IGF1R with unchanged levels of insulin receptor (IR), and failed to respond to IGF-I-induced Akt activation, proliferation, and anchorage-independent growth while retaining responsiveness to both insulin and IGF-II. The IGF1R antibody dalotuzumab inhibited IGF-I-mediated Akt phosphorylation, proliferation, and anchorage-independent growth in parental cells, but had no effect on TamR cells. An IGF1R tyrosine kinase inhibitor, AEW541, with equal potency for the IGF1R and IR, inhibited IGF-I-, IGF-II-, and insulin-stimulated Akt phosphorylation, proliferation, and anchorage-independent growth in parental cells. Interestingly, AEW541 also inhibited insulin- and IGF-II-stimulated effects in TamR cells. Tamoxifen-treated xenografts also had reduced levels of IGF1R, and dalotuzumab did not enhance the effect of tamoxifen. We conclude that cells selected for tamoxifen resistance in vitro have downregulated IGF1R making antibodies directed against this receptor ineffective. Inhibition of IR may be necessary to manage tamoxifen-resistant breast cancer.

Effects of epidermal growth factor receptor and insulin-like growth factor 1 receptor inhibition on proliferation and intracellular signaling in cutaneous SCCHN: potential for dual inhibition as a therapeutic modality

BACKGROUND

Combined inhibition of epidermal growth factor receptor (EGFR) and insulin-like growth factor-1 receptor (IGF-1R) has been proposed as a therapy for cutaneous squamous cell carcinoma of the head and neck (SCCHN).

METHODS

Receptor expression and downstream signaling were assessed in cutaneous squamous cell carcinoma (SCC) cell lines and patient samples. EGFR and IGF-1R signaling was inhibited in cutaneous SCC cell lines using erlotinib and/or picropodophyllin.

RESULTS

EGFR and IGF-1R were overexpressed in cutaneous SCCHN specimens relative to normal skin. Dual inhibition of both receptors prevented cell growth and decreased activation of Akt and p42/44 mitogen-activated protein kinase (MAPK) more effectively than either inhibitor alone.

CONCLUSION

Dual inhibition of EGFR and IGF-1R is effective at blocking cell growth, and is correlated with inhibition of Akt and p42/44 MAPK, suggesting that this may be a promising treatment for cutaneous SCCHN.

Development of tetravalent IgG1 dual targeting IGF-1R-EGFR antibodies with potent tumor inhibition

In this study we present novel bispecific antibodies that simultaneously target the insulin-like growth factor receptor type I (IGF-1R) and epidermal growth factor receptor (EGFR). For this purpose disulfide stabilized scFv domains of the EGFR/ADCC antibody GA201 were fused via serine-glycine connectors to the C-terminus of the heavy (XGFR2) or light chain (XGFR4), or the N-termini of the light (XGFR5) or heavy chain (XGFR3) of the IGF-1R antibody R1507 as parental IgG1 antibody. The resulting bispecific IGF-1R-EGFR antibodies XGFR2, XGFR3 and XGFR4 were successfully generated with yields and stability comparable to conventional IgG1 antibodies. They effectively inhibited IGF-1R and EGFR phosphorylation and 3D proliferation of H322M and H460M2 tumor cells, induced strong down-modulation of IGF-1R as well as enhanced EGFR down-modulation compared to the parental EGFR antibody GA201 and were ADCC competent. The bispecific XGFR derivatives showed a strong format dependent influence of N- or C-terminal heavy and light chain scFv attachment on ADCC activity and an increase in receptor downregulation over the parental combination in vitro. XGFR2 and XGFR4 were selected for in vivo evaluation and showed potent anti-tumoral efficacy comparable to the combination of monospecific IGF-1R and EGFR antibodies in subcutaneous BxPC3 and H322M xenograft models. In summary, we have managed to overcome issues of stability and productivity of bispecific antibodies, discovered important antibody fusion protein design related differences on ADCC activity and receptor downmodulation and show that IGF-1R-EGFR antibodies represent an attractive therapeutic strategy to simultaneously target two key components de-regulated in multiple cancer types, with the ultimate goal to avoid the formation of resistance to therapy.

AMG 479, a novel IGF-1-R antibody, inhibits endometrial cancer cell proliferation through disruption of the PI3K/Akt and MAPK pathways

Our goal was to evaluate the therapeutic potential of a novel antibody to the insulin growth factor-1 receptor (IGF-1-R; AMG 479) in endometrial cancer cells. The endometrial cancer cell lines, ECC-1/PRAB72 and RL-95-2, were used. Treatment with AMG 479 (0.02-200 nmol/L) resulted in inhibition of cell proliferation at 72 to 120 hours. Insulin growth factor-1 (0.15-7.5 nmol/L) stimulated growth in both cell lines (range of 15%-42%, P = .0025-.0445), which could be blocked by pretreatment with AMG 479 (mean of 29% for ECC-1/PRAB72, P = .006-.007; mean of 36% for RL-95-2, P = .0002-.0045). AMG 479 suppressed IGF-1-R kinase activity in a dose-dependent manner. Cells treated with AMG 479 underwent either G1 (ECC-1/PRAB72) or G2 (RL-95-2) arrest. AMG 479 decreased human telomerase reverse transcriptase (hTERT) mRNA expression in both endometrial cancer cell lines. Treatment with AMG 479 rapidly blocked IGF-1-induced phosphorylation of IFG-1-R, Akt, and p44/42. Thus, manipulation of the IGF-1-R pathway may serve as a promising therapeutic strategy for the treatment of endometrial cancer.

Monoclonal antibodies for the treatment of cancer

Over the past decade, the clinical utility of monoclonal antibodies has been realized and antibodies are now a mainstay for the treatment of cancer. Antibodies have the unique capacity to target and kill tumor cells while simultaneously activating immune effectors to kill tumor cells through the complement cascade or antibody-dependent cellular cytotoxicity (ADCC). This multifaceted mechanism of action combined with target specificity underlies the capacity of antibodies to elicit anti-tumor responses while minimizing the frequency and magnitude of adverse events. This review will focus on mechanisms of action, clinical applications and putative mechanisms of resistance to monoclonal antibody therapy in the context of cancer.

IGF-1 receptor is down-regulated by sunitinib induces MDM2-dependent ubiquitination

The insulin like growth factor receptor subtype 1(IGF-1R) plays an important role in cancers transformation and progression. The aim is to investigate the effects of sunitinib on IGF-1R cell signaling transduction, especially on receptor phosphorylation and ubiquitination. In HEK293 cells, IGF-1R signaling pathways are activated in response to IGF-1, which induces obvious phosphorylations of receptor tyrosine and Akt, ERK. However, the phosphorylations of receptor tyrosine, Akt and ERK were significant inhibited by sunitinib. We found that both IGF-1 and sunitinib obviously down regulated the IGF-1R expression. For analysis the ubiquitination, HEK293 cells were simulated with 100 ng/ml IGF-1 or 10 nM sunitinib for 10 min after serum starvation for 24 h. Both IGF-1 and sunitinib could obviously induce the IGF-1R ubiquitination at 10 min compared with control (only serum free, no stimulation), indicating IGF-1 and sunitinib down-regulate the IGF-1R by increasing the receptor degradation through ubiquitination dependent proteasome pathway. We also found that MDM2 combined to IGF-1R in response to sunitinib stimulation. To confirm it, HEK293 cells were transfected with human HA-MDM2 (+MDM2) or siRNA to MDM2 (−MDM2). Following 24 h serum starvation, cells were stimulated with 10 nM sunitinib for 10 min. In over-expressed MDM2 cells, IGF-1R was more ubiquitinated than that in mock-transfected cells (control), and no ubiquitination in −MDM2 cells. These results mean that sunitinib mediates ubiquitination of IGF-1R dependent on MDM2. In summary, sunitinib could block signaling transduction and mediate degradation of IGF-1R.

Pharmacodynamic modeling of sequence-dependent antitumor activity of insulin-like growth factor blockade and gemcitabine

Agents that block insulin-like growth factor (IGF) signaling are under investigation in clinical trials. Antitumor effects are likely to be enhanced when combined with other agents, but administration sequence effects on activity are not well-described. Three breast cancer cell lines (MCF-7, MDA-MB-231, and Hs-578T) were treated with Gemcitabine and small molecule receptor tyrosine kinase inhibitor cis-3-[3-(4-methyl-piperazin-l-yl)-cyclobutyl]1-(2-phenyl-quinolin-7-yl)-imidazo [1,5-a]pyrazin-8-ylamine (PQIP) as single agents and then in combination in the forward (Gemcitabine followed by PQIP) and reverse (PQIP followed by Gemcitabine) sequences. Antitumor effects were assessed longitudinally by Bayesian analysis using WinBUGS. The pharmacodynamic model adequately predicted the observed data. The differences in the cell-kill rate constants for the forward vs. reverse sequence ranged from 0.11 to 0.64 (day(-1)), and statistical significance was generally dependent on cell line and PQIP concentration. These data indicate that treatment with Gemcitabine first, followed by PQIP is superior to the reverse sequence in vitro.

Polyubiquitination of insulin-like growth factor I receptor (IGF-IR) activation loop promotes antibody-induced receptor internalization and down-regulation

Ubiquitination has been implicated in negatively regulating insulin-like growth factor I receptor (IGF-IR) activity. Because of the relative stability of IGF-IR in the presence of ligand stimulation, IGF-IR ubiquitination sites have yet to be mapped and characterized, thus preventing a direct demonstration of how the receptor ubiquitination contributes to downstream molecular cascades. We took advantage of an anti-IGF-IR antibody (h10H5) that induces more efficient receptor down-regulation to show that IGF-IR is promptly and robustly ubiquitinated. The ubiquitination sites were mapped to the two lysine residues in the IGF-IR activation loop (Lys-1138 and Lys-1141) and consisted of polyubiquitin chains formed through both Lys-48 and Lys-29 linkages. Mutation of these ubiquitinated lysine residues resulted in decreased h10H5-induced IGF-IR internalization and down-regulation as well as a reduced cellular response to h10H5 treatment. We have therefore demonstrated that IGF-IR ubiquitination contributes critically to the down-regulating and antiproliferative activity of h10H5. This finding is physiologically relevant because insulin-like growth factor I appears to mediate ubiquitination of the same major sites as h10H5 (albeit to a lesser extent), and ubiquitination is facilitated by pre-existing phosphorylation of the receptor in both cases. Furthermore, identification of a breast cancer cell line with a defect in IGF-IR ubiquitination suggests that this could be an important tumor resistance mechanism to evade down-regulation-mediated negative regulation of IGF-IR activity in cancer.

Plasma and tissue insulin-like growth factor-I receptor (IGF-IR) as a prognostic marker for prostate cancer and anti-IGF-IR agents as novel therapeutic strategy for refractory cases: a review

Cancer database analysis indicates that prostate cancer is one of the most seen cancers in men meanwhile composing the leading cause of morbidity and mortality among developed countries. Current available therapies are surgery, radiotherapy and androgene ablation for prostate carcinoma. The response rate is as high nearly 90% however, most of these recur or become refractory and androgene independent (AI). Therefore recent studies intensified on molecular factors playing role on development of prostate carcinoma and novel treatment strategies targetting these factors and their receptors. Insulin-like growth factor-I (IGF-I) and its primary receptor insulin-like growth factor receptor-I (IGF-IR) are among these factors. Biologic functions and role in malign progression are primarily achieved via IGF-IR which is a type 2 tyrosine kinase receptor. IGF-IR plays an important role in mitogenesis, angiogenesis, transformation, apoptosis and cell motility. It also generates intensive proliferative signals leading to carcinogenesis in prostate tissue. So IGF-IR and its associated signalling system have provoked considerable interest over recent years as a novel therapeutic target in cancer. In this paper it is aimed to sum up the lately published literature searching the relation of IGF-IR and prostate cancer in terms of incidence, pathologic features, and prognosis. This is followed by a discussion of the different possible targets within the IGF-1R system, and drugs developed to interact at each target. A systems-based approach is then used to review the in vitro and in vivo data in the published literature of the following compounds targeting IGF-1R components using specific examples: growth hormone releasing hormone antagonists (e.g. JV-1-38), growth hormone receptor antagonists (e.g. pegvisomant), IGF-1R antibodies (e.g. CP-751,871, AVE1642/EM164, IMC-A12, SCH-717454, BIIB022, AMG 479, MK-0646/h7C10), and IGF-1R tyrosine kinase inhibitors (e.g. BMS-536942, BMS-554417, NVP-AEW541, NVP-ADW742, AG1024, potent quinolinyl-derived imidazo (1,5-a)pyrazine PQIP, picropodophyllin PPP, nordihydroguaiaretic acid Insm-18/NDGA). And the other end point is to yield an overview on the recent progress about usage of this receptor as a novel anticancer agent of targeted therapies in treatment of prostate carcinoma.

The role of the insulin-like growth factor signaling pathway in non-small cell lung cancer and other solid tumors

The type 1 insulin-like growth factor receptor (IGF-1R) and its downstream signaling components have become increasingly recognized as having a driving role in the development of malignancy, and consequently IGF-1R has become a potential target for cancer therapy. Several inhibitors of IGF-1R are in clinical development for the treatment of solid tumors, including non-small cell lung cancer (NSCLC). These IGF-1R-targeted agents include monoclonal antibodies such as cixutumumab (IMC-A12), AMG-479, AVE1642, BIIB022, dalotuzumab (MK-0646), and robatumumab (Sch717454), the ligand neutralizing antibody Medi-573, and the small molecule inhibitors BMS-754807, linsitinib (OSI-906), XL228, and AXL1717. Two phase III trials of the anti-IGF-1R monoclonal antibody, figitumumab (CP-751,871), were discontinued in 2010 as it was considered unlikely either trial would meet their primary endpoints. In light of disappointing clinical data with figitumumab and other targeted agents, it is likely that the use of molecular markers will become important in predicting response to treatment. This review outlines the role of IGF-1R signaling in solid tumors with a particular focus on NSCLC, and provides an overview of clinical data.

Defining new paradigms for the treatment of pancreatic cancer

Pancreatic cancer (PC) is the fourth leading cause of cancer death in the United States. Despite significant improvement in understanding disease biology, the 5-year survival rates remain less than 5%. Targeted agents failed to add any meaningful survival benefit in this patient population despite very promising pre-clinical data. The new paradigm for the treatment of PC must emphasize validation of targeted agents in the appropriate pre-clinical models, identification of predictive markers for disease response, and extending range of targets into cancer stem cells and tumor microenvironment. It is also necessary to perform studies that are designed to address the various stages of disease with respect to study endpoints and application of a multimodality approach in management. Phase III trials should only be considered when a strong efficacy signal is demonstrated in phase II studies that is based on a survival endpoint. This review will focus on the development of novel treatments in pancreas cancer and the proposed design of future clinical trials.