Safety, tolerability, and pharmacokinetics of the anti-IGF-1R monoclonal antibody figitumumab in patients with refractory adrenocortical carcinoma

ERK phosphorylation is predictive of resistance to IGF-1R inhibition in small cell lung cancer

New therapies are critically needed to improve the outcome for patients with small cell lung cancer (SCLC). Insulin-like growth factor 1 receptor (IGF-1R) inhibition is a potential treatment strategy for SCLC: the IGF-1R pathway is commonly upregulated in SCLC and has been associated with inhibition of apoptosis and stimulation of proliferation through downstream signaling pathways, including phosphatidylinositol-3-kinase-Akt and mitogen-activated protein kinase. To evaluate potential determinants of response to IGF-1R inhibition, we assessed the relative sensitivity of 19 SCLC cell lines to OSI-906, a small molecule inhibitor of IGF-1R, and the closely related insulin receptor. Approximately one third of these cell lines were sensitive to OSI-906, with an IC50 < 1 μmol/L. Cell line expression of IGF-1R, IR, IGF-1, IGF-2, IGFBP3, and IGFBP6 did not correlate with sensitivity to OSI-906. Interestingly, OSI-906 sensitive lines expressed significantly lower levels of baseline phospho-ERK relative to resistant lines (P = 0.006). OSI-906 treatment resulted in dose-dependent inhibition of phospho-IGF-1R and phospho-Akt in both sensitive and resistant cell lines, but induced apoptosis and cell-cycle arrest only in sensitive lines. We tested the in vivo efficacy of OSI-906 using an NCI-H187 xenograft model and two SCLC patient xenografts in mice. OSI-906 treatment resulted in 50% tumor growth inhibition in NCI-H187 and 30% inhibition in the primary patient xenograft models compared with mock-treated animals. Taken together our data support IGF-1R inhibition as a viable treatment strategy for a defined subset of SCLC and suggest that low pretreatment levels of phospho-ERK may be indicative of sensitivity to this therapeutic approach.

A kinase-independent biological activity for insulin growth factor-1 receptor (IGF-1R) : implications for inhibition of the IGF-1R signal

It has been demonstrated that epidermal growth factor receptor (EGFR) can have kinase independent activity. EGFR kinase-independent function maintains intracellular glucose levels via sodium glucose transporter protein 1 (SGLT1) and supports cell survival. It is plausible that this phenomenon can apply to other receptor tyrosine kinases. We found that transfection of insulin-like growth factor receptor (IGF-1R) siRNA into HEK293 (human embryonic kidney) and MCF7 (metastatic breast cancer) cells result in decreased intracellular glucose levels, whereas treatment with an IGF-1R tyrosine kinase inhibitor OSI-906 did not affect intracellular glucose levels. In addition, IGF-1R interacted with SGLT1 in a manner similar to that previously reported with EGFR. The combination of IGF-1R siRNA and OSI-906 resulted in decreased viability of HEK293 and MCF7 cell lines compared to either agent alone. Collectively, these experiments suggest that IGF-1R, has kinase-independent biologic functions and provide a rationale for combining anti-IGF-1R antibodies or siRNA and IGF-1R small molecule inhibitors.

Insulin growth factor receptor (IGF-1R) antibody cixutumumab combined with the mTOR inhibitor temsirolimus in patients with metastatic adrenocortical carcinoma

Background:

Adrenocortical carcinoma (ACC) is a rare and aggressive endocrine malignancy without an available effective systemic chemotherapy. Insulin growth factor 2 (IGF-2) overexpression leading to the activation of the IGF-1 receptor (IGF-1R)/mammalian target of rapamycin (mTOR) pathway is well described in ACC. Cixutumumab, a fully human IgG1 monoclonal antibody directed at IGF-1R was combined with temsirolimus on the basis of preclinical data.

Methods:

Patients received cixutumumab, 3–6 mg kg⁻¹ intravenously (IV) weekly, and temsirolimus, 25–37.5 mg IV weekly (4-week cycles), with restaging after 8 weeks.

Results:

Twenty-six patients were enrolled (13 (50%) men); median age, 47 years; median number of prior therapies, 4. Five patients previously received an IGF-1R inhibitor and one, temsirolimus. The most frequent toxicities, at least possibly drug related, were grade 1–2 thrombocytopenia (38%), mucositis (58%), hypercholesterolaemia (31%), hypertriglyceridemia (35%), and hyperglycaemia (31%). In all, 11 of 26 patients (42%) achieved stable disease (SD) >6 months (duration range=6–21 months) with 3 of the 11 having received a prior IGF-1R inhibitor.

Conclusion:

Cixutumumab combined with temsirolimus was well tolerated and >40% of patients achieved prolonged SD.

Targeting estrogen receptor-α reduces adrenocortical cancer (ACC) cell growth in vitro and in vivo: potential therapeutic role of selective estrogen receptor modulators (SERMs) for ACC treatment

CONTEXT

Adrenocortical carcinoma (ACC) is a rare tumor with a very poor prognosis and no effective treatment. ACC is characterized by an increased production of IGF-II and by estrogen receptor (ER)-α up-regulation.

OBJECTIVE

The objective of this study was to define the role played by ERα in 17β-estradiol (E2)- and IGF-II-dependent ACC growth and evaluate whether selective estrogen receptor modulators are effective in controlling ACC growth in vivo.

EXPERIMENTAL DESIGN

The human adrenocortical cell line H295R was used as an in vitro model and to generate xenograft tumors in athymic nude mice.

RESULTS

In H295R cells IGF-II controlled expression of steroidogenic factor-1 that, in turn, increased aromatase transcription and, consequently, estrogen production, inducing cell proliferation. ERα silencing significantly blocked E2- and IGF-II-dependent cell proliferation. This effect was dependent on the regulation of cyclin D1 expression by ERα, activated in response to both E2 and IGF-II. In fact, IGF-II induced ERα activation by phosphorylating serine 118 and 167. Furthermore, we demonstrated that ERα mediated E2-induced nongenomic signaling that stimulated IGF-I receptor (IGF1R), ERK1/2, and AKT phosphorylation, resulting in a ligand-independent activation of the IGF1R-induced pathway. In addition, E2 potentiated this pathway by up-regulating IGF1R expression as a consequence of increased cAMP-responsive element binding protein activation and binding to IGF1R promoter. The estrogen antagonist, hydroxytamoxifen, the active metabolite of tamoxifen, reduced IGF1R protein levels and both E2- and IGF-II-induced cell proliferation. Moreover, H295R xenograft growth was strongly reduced by tamoxifen.

CONCLUSION

These findings establish a critical role for ERα in E2- and IGF-II-dependent ACC proliferation and provide a rationale for targeting ERα to control the proliferation of ACC.

Clinical development of insulin-like growth factor receptor--1 (IGF-1R) inhibitors: at the crossroad?

Insulin like growth factor receptor (IGF-1R) targeting became one of the most investigated areas in anticancer drug development during the last decade. Strategies aiming to block IGF-1R activity include monoclonal antibodies, tyrosine kinase inhibitors and anti-ligands antibodies. Initial enthusiasm quickly encountered challenges. Unfortunately the validation of the efficacy of IGF-1R targeted agents in large clinical trials failed, however anecdotal single agent activity was seen in early studies. Consequently, questions regarding the selection of right target population and the appropriate trial design are arising. Despite the plethora of clinical trials conducted no predictive biomarker has been validated so far and resistance mechanisms to IGF-1R inhibitors remain unclear. The other issue to be addressed is how to best combine IGF-1R inhibitors with other therapeutic approaches. This review highlights the most relevant clinical data emphasizing the main tumor types where IGF-1R inhibition showed potential interest. We also tried to extract based on clinical and translational data some candidate biomarkers that could help better to select patient population who potentially could benefit most from this therapeutic approach.

Adrenocortical Carcinoma: Current Therapeutic State-of-the-Art

Adrenocortical carcinoma (ACC) is a rare, aggressive malignancy that generally conveys a poor prognosis. Currently, surgical resection is considered the lone curative treatment modality. In addition, the low prevalence of ACC has limited effective clinical trial design to develop evidence-based approaches to ACC therapy. The proper role of radio- and chemotherapy treatment for ACC is still being defined. Similarly, the molecular pathogenesis of ACC remains to be fully characterized. Despite these challenges, progress has been made in several areas. After years of refinement, an internationally accepted staging system has been defined. International collaborations have facilitated increasingly robust clinical trials, especially regarding agent choice and patient selection for chemotherapeutics. Genetic array data and molecular profiling have identified new potential targets for rational drug design as well as potential tumor markers and predictors of therapeutic response. However, these advances have not yet been translated into a large outcomes benefit for ACC patients. In this paper, we summarize established therapy for ACC and highlight recent findings in the field that are impacting clinical practice.

Current and emerging therapeutic options in adrenocortical cancer treatment

Adrenocortical carcinoma (ACC) is a very rare endocrine tumour, with variable prognosis, depending on tumour stage and time of diagnosis. The overall survival is five years from detection. Radical surgery is considered the therapy of choice in the first stages of ACC. However postoperative disease-free survival at 5 years is only around 30% and recurrence rates are frequent. o,p'DDD (ortho-, para'-, dichloro-, diphenyl-, dichloroethane, or mitotane), an adrenolytic drug with significant toxicity and unpredictable therapeutic response, is used in the treatment of ACC. Unfortunately, treatment for this aggressive cancer is still ineffective. Over the past years, the growing interest in ACC has contributed to the development of therapeutic strategies in order to contrast the neoplastic spread. In this paper we discuss the most promising therapies which can be used in this endocrine neoplasia.

Figitumumab combined with carboplatin and paclitaxel in treatment-naïve Japanese patients with advanced non-small cell lung cancer

OBJECTIVES

The insulin-like growth factor (IGF) signaling pathway has been implicated in the pathogenesis of numerous tumor types, including non-small cell lung cancer (NSCLC). Figitumumab is a fully human IgG2 monoclonal antibody against IGF-1 receptor (IGF-1R).

METHODS

This phase I, open-label, dose-escalation study (ClinicalTrials.gov: NCT00603538) assessed the safety and tolerability of figitumumab (6, 10 and 20 mg/kg) in combination with carboplatin (area under the curve: 6 mg·min/mL) and paclitaxel (200 mg/m(2)) in Japanese patients (N = 19) with chemotherapy-naïve, advanced NSCLC. Treatments were administered intravenously on day 1 of a 21-day cycle for four to six cycles. Pharmacokinetics, biomarkers, and antitumor activity were also evaluated.

RESULTS

Figitumumab in combination with carboplatin and paclitaxel was well tolerated at doses up to 20 mg/kg; no dose-limiting toxicities were observed at this dose level. When given in combination, figitumumab plasma exposure increased in an approximately dose-proportional manner. The approximate 2-fold accumulation following repeated administration supported the 21-day regimen as appropriate for figitumumab administration. Serum total IGF-1 and IGF binding protein-3 concentrations increased following figitumumab dosing, but a clear dose-dependent relationship was not demonstrated. Seven of 18 evaluable patients experienced a partial response.

CONCLUSIONS

Figitumumab 20 mg/kg in combination with carboplatin and paclitaxel was well tolerated in chemotherapy-naïve Japanese patients with NSCLC. Further analysis of biomarker data is necessary for the development of figitumumab therapy.

Insulin-like growth factor receptor inhibitors: baby or the bathwater?

The success of targeted therapies for cancer is undisputed; strong preclinical evidence has resulted in the approval of several new agents for cancer treatment. The type I insulin-like growth factor receptor (IGF1R) appeared to be one of these promising new targets. Substantial population and preclinical data have all pointed toward this pathway as an important regulator of tumor cell biology. Although early results from clinical trials that targeted the IGF1R showed some evidence of response, larger randomized phase III trials have not shown clear clinical benefit of targeting this pathway in combination with conventional strategies. These disappointing results have resulted in the discontinuation of several anti-IGF1R programs. However, the conduct of these trials has brought to the forefront several important factors that need to be considered in the conduct of future clinical trials. The need to develop biomarkers, a clearer understanding of insulin receptor function, and defining rational combination regimens all require further consideration. In this commentary, the current state of IGF1R inhibitors in cancer therapy is reviewed.

The next generation of therapies for adrenocortical cancers

Adrenocortical carcinoma (ACC) is a rare cancer for which few treatment options have been available. Currently, the best available treatment involves combination chemotherapy with the adrenolytic drug mitotane, although the response rate remains modest. Over the past 10 years there has been renewed interest in the field owing to the recognition that targeted therapies may provide new avenues for effective treatment of this deadly disease. Molecular analyses have revealed specific signaling alterations in ACC, and advances in drug development have generated the tools to block these pathways. Although convincing evidence for the effectiveness of targeted therapies is not currently available, these studies are in progress and should shift the prognosis of this disease in the years to come.

Genetic aspects of adrenocortical tumours and hyperplasias

Adrenocortical tumours (ACT), which include adenomas, carcinomas and adrenal hyperplasia, may be associated with genetic syndromes, such as Li-Fraumeni syndrome, Beckwith-Wiedemann syndrome, multiple endocrine neoplasia type 1, familial adenomatous polyposis and Carney complex. Genetic defects have been found to be responsible for the disease in most of these syndromes, allowing genetic counselling to affected patients and family members. Here, we summarize the clinical criteria of these hereditary syndromes and briefly describe the genetic alterations related to them. In addition, we discuss the involvement of various genetic defects in the development of sporadic adrenocortical tumours.

Quantifying insulin receptor isoform expression in FFPE breast tumors

BACKGROUND

The development of predictive biomarkers for IGF targeted anti-cancer therapeutics remains a critical unmet need. The insulin receptor A isoform (InsR-A) has been identified as a possible biomarker candidate but quantification of InsR-A in widely available formalin fixed paraffin embedded (FFPE) tissues is complicated by its similarities with the metabolic signaling insulin receptor isoform B (InsR-B). In the present study, qPCR based assays specific for InsR-A, InsR-B and IGF-1R were developed for use in FFPE tissues and tested for feasible use in clinical archived FFPE estrogen receptor (ER)+and ER- breast cancer tumors.

DESIGN

FFPE compatible primer sets were designed with amplicon sizes of less than 60 base pairs and validated for target specificity, assay repeatability and amplification efficiency. FFPE tumors from ER+ (n=83) and ER-(n=64) primary untreated breast cancers, and ER+ hormone refractory (HR ER+) (n=61) breast cancers were identified for feasibility testing. The feasible use of InsR-A and InsR-B qPCRs were tested using all tumor groups and the feasibility of IGF-1R qPCR was determined using HR ER+ tumors.

RESULTS

All qPCR assays were highly reproducible with amplification efficiencies between 96-104% over a 6 log range with limits of detection of 4 or 5 copies per reaction. Greater than 90% of samples were successfully amplified using InsR-A, InsR-B or IGF-1R qPCR primer sets and greater than 88% of samples tested amplified both InsR isoforms or both isoforms and IGF-1R. InsR-A was the predominant isoform in 82% ER+, 68% ER- and 100% HR ER+ breast cancer. Exploratory analyses demonstrated significantly more InsR-A expression in ER+ and HR ER+ groups compared to InsR-B (ER+ p<0.05, HR ER+ p<0.0005) and both groups had greater InsR-A expression when compared to ER- tumors (ER+ p<0.0005, HR ER+ p<0.05). IGF-1R expression of HR ER+ tumors was lower than InsR-A (p<0.0005) but higher than InsR-B (p<0.0005). The InsR-B expression of HR ER+ tumors was significantly reduced compared other tumor subgroups (ER+ and ER-, p<0.0005) and lead to a significant elevation of HR ER+ InsR-A: InsR-B ratios (ER+ and ER-, p<0.0005).

CONCLUSIONS

The validated, highly sensitive InsR-A and InsR-B qPCR based assays presented here are the first to demonstrate the feasible amplification of InsR isoforms in FFPE tissues. Quantification data generated from this feasibility study indicating InsR-A is more predominant than InsR-B in breast cancer support the use of these assays for further investigation of InsR-A and InsR-B as predictive biomarkers for IGF targeted therapeutics.

Site-specific targeting of antibody activity in vivo mediated by disease-associated proteases

As a general strategy to selectively target antibody activity in vivo, a molecular architecture was designed to render binding activity dependent upon proteases in disease tissues. A protease-activated antibody (pro-antibody) targeting vascular cell adhesion molecule 1 (VCAM-1), a marker of atherosclerotic plaques, was constructed by tethering a binding site-masking peptide to the antibody via a matrix metalloprotease (MMP) susceptible linker. Pro-antibody activation in vitro by MMP-1 yielded a 200-fold increase in binding affinity and restored anti-VCAM-1 binding in tissue sections from ApoE⁻/⁻ mice ex vivo. The pro-antibody was efficiently activated by native proteases in aorta tissue extracts from ApoE⁻/⁻, but not from normal mice, and accumulated in aortic plaques in vivo with enhanced selectivity when compared to the unmodified antibody. Pro-antibody accumulation in aortic plaques was MMP-dependent, and significantly inhibited by a broad-spectrum MMP inhibitor. These results demonstrate that the activity of disease-associated proteases can be exploited to site-specifically target antibody activity in vivo.

Adrenocortical carcinoma: past, present, and future

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy. Due to its rarity, heterogeneity, and a lack of a comprehensive understanding of the pathogenesis, little progress has been made in treatment and outcomes. The current review explores the past, present, and future of the understanding and treatment of this disease process.

Differences in the molecular mechanisms of adrenocortical tumorigenesis between children and adults

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. The incidence of pediatric adrenocortical tumors (ACT) is remarkably high in Southern Brazil, where it is estimated to be 15 times greater than the world occurrence, due to a high frequency of a germline mutation (p.R337H) of the TP53 gene. Differently from adults, pediatric adrenocortical neoplasms with apparently poor prognosis based on histopathological features have often a good clinical outcome. A high Weiss score is definitely not a good predictor of survival in children, but it is much more discriminative of a poor outcome in adult tumors. Besides important differences in prognosis, adrenocortical tumorigenesis has distinct patterns between children and adults. In this review, we summarize recent data from ours and other Institutions, showing that the prognostic importance of molecular markers is striking different between pediatric and adult ACT. Although the majority of pediatric ACT are associated with p.R337H germline mutation, it is not a predictor of poor outcome in children and adolescents with ACT. On the other side, TP53 somatic mutations define a subgroup of adult ACC with different tumorigenesis and unfavorable prognosis. IGF system has a central role in the malignant phenotype of ACT, but in adult tumors it is mediated by IGF2 over-expression and in pediatric tumors by IGF1R over-expression. Finally, SF1 over-expression is associated with decreased overall survival and recurrence-free survival in adult ACC, but not in the pediatric group. In conclusion, discriminating benign and malignant behavior is more challenging in pediatric ACT than in adult tumors.

Heterodimerization of glycosylated insulin-like growth factor-1 receptors and insulin receptors in cancer cells sensitive to anti-IGF1R antibody

BACKGROUND

Identification of predictive biomarkers is essential for the successful development of targeted therapy. Insulin-like growth factor 1 receptor (IGF1R) has been examined as a potential therapeutic target for various cancers. However, recent clinical trials showed that anti-IGF1R antibody and chemotherapy are not effective for treating lung cancer.

METHODOLOGY/PRINCIPAL FINDINGS

In order to define biomarkers for predicting successful IGF1R targeted therapy, we evaluated the anti-proliferation effect of figitumumab (CP-751,871), a humanized anti-IGF1R antibody, against nine gastric and eight hepatocellular cancer cell lines. Out of 17 cancer cell lines, figitumumab effectively inhibited the growth of three cell lines (SNU719, HepG2, and SNU368), decreased p-AKT and p-STAT3 levels, and induced G 1 arrest in a dose-dependent manner. Interestingly, these cells showed co-overexpression and altered mobility of the IGF1R and insulin receptor (IR). Immunoprecipitaion (IP) assays and ELISA confirmed the presence of IGF1R/IR heterodimeric receptors in figitumumab-sensitive cells. Treatment with figitumumab led to the dissociation of IGF1-dependent heterodimeric receptors and inhibited tumor growth with decreased levels of heterodimeric receptors in a mouse xenograft model. We next found that both IGF1R and IR were N-linked glyosylated in figitumumab-sensitive cells. In particular, mass spectrometry showed that IGF1R had N-linked glycans at N913 in three figitumumab-sensitive cell lines. We observed that an absence of N-linked glycosylation at N913 led to a lack of membranous localization of IGF1R and figitumumab insensitivity.

CONCLUSION AND SIGNIFICANCE

The data suggest that the level of N-linked glycosylated IGF1R/IR heterodimeric receptor is highly associated with sensitivity to anti-IGF1R antibody in cancer cells.

Targeting the insulin-like growth factor axis for the development of novel therapeutics in oncology

Insulin-like growth factors (IGF) are polypeptide hormones with potent anabolic and mitogenic effects that regulate cell growth and differentiation. Dysregulation of the IGF axis has been well documented in the development and progression of multiple types of cancer. As a result, compounds targeting the IGF axis have become an area of intense preclinical and clinical research for cancer therapeutics. The IGF axis is intimately involved with the insulin-signaling pathway because of their close homologies. This homology may explain hurdles encountered in the clinical development of IGF-targeted therapies, such as less-than-expected antitumor efficacy that may arise from compensatory increases in the activity of insulin receptor isoform A (IR-A), in response to IGF-I receptor (IGF-IR) inhibition and perturbations in glucose homeostasis, arising from the inhibition of insulin receptor isoform B (IR-B) activity. In this brief review, we compare differentiating factors that characterize the 3 major classes of IGF-targeting compounds: therapeutic antibodies that target IGF-IR, small molecule tyrosine kinase inhibitors that inhibit kinase activities of IGF-IR and IR, and antibodies that target IGF ligands.

Targeting the insulin-like growth factor 1 receptor (IGF1R) signaling pathway for cancer therapy

INTRODUCTION

The IGF system controls growth, differentiation, and development at the cellular, organ and organismal levels. IGF1 receptor (IGF1R) signaling is dysregulated in many cancers. Numerous clinical trials are currently assessing therapies that inhibit either growth factor binding or IGF1R itself. Therapeutic benefit, often in the form of stable disease, has been reported for many different cancer types.

AREAS COVERED

Canonical IGF signaling and non-canonical pathways involved in carcinogenesis. Three recent insights into IGF1R signaling, namely hybrid receptor formation with insulin receptor (INSR), insulin receptor substrate 1 nuclear translocation, and evidence for IGF1R/INSR as dependence receptors. Different approaches to targeting IGF1R and mechanisms of acquired resistance. Possible mechanisms by which IGF1R signaling supports carcinogenesis and specific examples in different human tumors.

EXPERT OPINION

Pre-clinical data justifies IGF1R as a target and early clinical trials have shown modest efficacy in selected tumor types. Future work will focus upon assessing the usefulness or disadvantages of simultaneously targeting the IGF1R and INSR, biomarker development to identify potentially responsive patients, and the use of IGF1R inhibitors in combination therapies or as an adjunct to conventional chemotherapy.

Insulin-like growth factor: current concepts and new developments in cancer therapy

The insulin-like growth factor (IGF) family and the IGF-1 receptor (IGF-1R) play an important role in cancer. This intricate and complex signaling pathway provides many opportunities for therapeutic intervention, and several novel therapeutics aimed at the IGF-1R, particularly monoclonal antibodies and small molecule tyrosine kinase inhibitors, are under clinical investigation. This article provides a patent overview of the IGF signaling pathway and its complexity, addresses the justification for the use of IGF-1R-targeted therapy, and reviews the results of in vivo and in vitro novel therapeutics. Over the past year, the completion of several phase I, II, and III trials have provided interesting new information about the clinical activity of these novel compounds, particularly CP-751,871, IMC-A12, R1507, AMG-479, AVE-1642, MK-0646, XL-228, OSI-906, and BMS-754807. We review the important preliminary results from clinical trials with these compounds and conclude with a discussion about future therapeutic efforts.

Bitter melon (Momordica charantia) extract suppresses adrenocortical cancer cell proliferation through modulation of the apoptotic pathway, steroidogenesis, and insulin-like growth factor type 1 receptor/RAC-α serine/threonine-protein kinase signaling

Adrenocortical carcinomas are rare but present with extremely poor prognosis. One of the approaches to control cancer progression and reduce cancer risk is prevention through diet. Bitter melon is widely consumed as a vegetable and especially as a traditional medicine in many countries. In this study, we have used human and mouse adrenocortical cancer cells as an in vitro model to assess the efficacy of bitter melon extract (BME) as an anticancer agent. The protein concentrations of BME and other extracts were measured before use. First, BME treatment of adrenocortical cancer cells resulted in a significantly dose-dependent decrease in cell proliferation. However, we did not observe an antiproliferative effect in adrenocortical cancer cells treated with extracts from blueberry, zucchini, and acorn squash. Second, apoptosis of adrenocortical cancer cells was accompanied by increased caspase-3 activation and poly(ADP-ribose) polymerase cleavage. BME treatment enhanced cellular tumor antigen p53, cyclin-dependent kinase inhibitor 1A (also called p21), and cyclic AMP-dependent transcription factor-3 levels and inhibited G1/S-specific cyclin D1, D2, and D3, and mitogen-activated protein kinase 8 (also called Janus kinase) expression, suggesting an additional mechanism involving cell cycle regulation and cell survival. Third, BME treatment decreased the key proteins involved in steroidogenesis in adrenocortical cancer cells. BME treatment decreased the level of phosphorylation of cyclin-dependent kinase 7, which is required, at least in part, for steroidogenic factor 1 activation. Finally, we observed that BME treatment significantly reduced the level of insulin-like growth factor 1 receptor and its downstream signaling pathway as evidenced by lower levels of phosphorylated RAC-α serine/threonine-protein kinase. Taken together, these data illustrate the inhibitory effect of bitter melon on cell proliferation of adrenocortical cancer through modulation of diverse mechanisms.

[Adrenocortical carcinomas: therapeutic advances in 2011]

Adrenocortical cancer (ACC) is a rare aggressive malignancy with a poor prognosis (5-year survival: 45 %). Their management requires multidisciplinary expertise. Complete resection by an expert surgeon is the only curative treatment. Very few adjuvant treatments are available and their efficacy is not fully proved. Adjuvant mitotane therapy increases the disease-free survival in the majority of patients after surgery but further studies are needed to determine patients in whom this treatment is the more beneficial. Blood concentrations of mitotane between 14 and 20mg/l are necessary to have a full efficiency but this therapeutic window may cause side effects difficult to control. When aggressive parameters are present, radiotherapy is proposed. In case of residual or unresectable disease, combination of chemotherapy and mitotane is conventionally proposed. FIRM-ACT study establishes that EDP (etoposide, doxorubicine et cisplatine) is the most effective chemotherapy for progressive ACC. The first results of treatment with tyrosine kinase inhibitors, in patients with progressive disease despite one or two lines of chemotherapy are disappointing but this may be partly explained by the interaction with mitotane which reduces the plasma concentrations of sunitinib in particular. Clinical trials are underway to assess the effectiveness of other targeted therapies, including treatments acting on the IGF-1 receptor.

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.

Enhanced efficacy of IGF1R inhibition in pediatric glioblastoma by combinatorial targeting of PDGFRα/β

Pediatric glioblastoma (pGBM), although rare, is one of the leading causes of cancer-related deaths in children, with tumors essentially refractory to existing treatments. We have identified IGF1R to be a potential therapeutic target in pGBM due to gene amplification and high levels of IGF2 expression in some tumor samples, as well as constitutive receptor activation in pGBM cell lines. To evaluate the therapeutic potential of strategies targeting the receptor, we have carried out in vitro and in vivo preclinical studies using the specific IGF1R inhibitor NVP-AEW541. A modest inhibitory effect was seen in vitro, with GI(50) values of 5 to 6 μmol/L, and concurrent inhibition of receptor phosphorylation. Specific targeting of IGF1R with short interfering RNA decreased cell viability, diminished downstream signaling through phosphoinositide 3-kinase (PI3K), and induced G(1) arrest, effects mimicked by NVP-AEW541, both in the absence and presence of IGF2. Hallmarks of PI3K inhibition were observed after treatment with NVP-AEW541 by expression profiling and Western blot analysis. Phospho-receptor tyrosine kinase (RTK) arrays showed phosphorylation of platelet-derived growth factor receptor (PDGFR) α/β in pGBM cells, suggesting coactivation of an alternative RTK pathway. Treatment of KNS42 with the PDGFR inhibitor imatinib showed additional effects targeting the mitogen-activated protein kinase pathway, and cotreatment of the PDGFR inhibitor imatinib with NVP-AEW541 resulted in a highly synergistic interaction in vitro and increased efficacy after 14 days therapy in vivo compared with either agent alone. These data provide evidence that inhibition of IGF1R, in combination with other targeted agents, may be a useful and novel therapeutic strategy in pGBM.

Targeting the insulin-like growth factor signaling pathway: figitumumab and other novel anticancer strategies

INTRODUCTION

There are clear preclinical data that support the involvement of the insulin-like growth factor (IGF) signaling pathway in oncogenesis and cancer progression. Such evidence has led to the design and conduct of drug development programs targeting the IGF-I receptor (IGF-IR) over the past 10 years.

AREAS COVERED

This review details the structure and function of different members of the IGF system and related pathways, describes the rationale for targeting IGF-IR in cancer and updates the current advances in drug development. The preclinical development of figitumumab, the furthest developed mAb against IGF-IR, is examined as well as the reported data from Phase I - III clinical trials. Future prospects for this target and pathway are also discussed.

EXPERT OPINION

While there have been both successes and failures in the development of novel targeted therapeutics targeting the IGF pathway, the evaluation of such agents should continue, with greater emphasis placed on combinatorial strategies and the development of predictive biomarkers that enhance antitumor responses through appropriate patient selection.

Targeting the Insulin-Like Growth Factor 1 Receptor in Ewing's Sarcoma: Reality and Expectations

Ewing's sarcoma family of tumours comprises a group of very aggressive diseases that are potentially curable with multimodality treatment. Despite the undoubted success of current treatment, approximately 30% of patients will relapse and ultimately die of disease. The insulin-like growth factor 1 receptor (IGF-1R) has been implicated in the genesis, growth, proliferation, and the development of metastatic disease in Ewing's sarcoma. In addition, IGF1-R has been validated, both in vitro and in vivo, as a potential therapeutic target in Ewing's sarcoma. Phase I studies of IGF-1R monoclonal antibodies reported several radiological and clinical responses in Ewing's sarcoma patients, and initial reports of several Phase II studies suggest that about a fourth of the patients would benefit from IGF-1R monoclonal antibodies as single therapy, with approximately 10% of patients achieving objective responses. Furthermore, these therapies are well tolerated, and thus far severe toxicity has been rare. Other studies assessing IGF-1R monoclonal antibodies in combination with traditional cytotoxics or other targeted therapies are expected. Despite, the initial promising results, not all patients benefit from IGF-1R inhibition, and consequently, there is an urgent need for the identification of predictive markers of response.

Transcatheter arterial chemoembolization for liver metastases in patients with adrenocortical carcinoma

PURPOSE

To retrospectively evaluate the effectiveness, tolerance, and predictors of response to transcatheter arterial chemoembolization for treatment of liver metastases from adrenocortical carcinoma.

MATERIALS AND METHODS

Twenty-nine patients with progressive liver metastases from adrenocortical carcinoma were treated with transcatheter arterial chemoembolization. Rate and duration of tumor response were defined according to Response Evaluation Criteria In Solid Tumors. The size of liver metastases, percentage of liver involvement, and Lipiodol uptake were studied as potential predictive factors of response. Time to liver and metastatic lesion progression were considered as endpoints.

RESULTS

Three months after transcatheter arterial chemoembolization, a liver morphologic response was observed in six of 29 patients (21%), stabilization in 18 (62%), and progression in five (17%). According to per-lesion analysis (n = 103), a morphologic response was observed in 23 lesions (22%), stabilization in 67 (65%), and progression in 13 (13%). Higher response rates were observed in cases in which the diameter of the target metastasis was 3 cm or smaller (P = .002) and in cases of high Lipiodol uptake (> 50%; P < .0001). On per-patient and per-lesion bases, progression rates were 32% and 55% at 6 months and 23% and 38% at 12 months. The median time to progression was 9 months and median survival was 11 months after the first procedure.

CONCLUSIONS

Transcatheter arterial chemoembolization should be considered as part of the therapeutic arsenal to treat liver metastases from adrenocortical carcinoma. The size of liver metastases and the percentage of Lipiodol uptake may help identify patients likely to benefit most from transcatheter arterial chemoembolization.

Current and emerging therapies for advanced adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare but aggressive malignancy with a poor prognosis. Complete surgical resection offers the only potential for cure; however, even after apparently successful excision, local or metastatic recurrence is frequent. Treatment options for advanced ACC are severely limited. Mitotane is the only recognized adrenolytic therapy available; however, response rates are modest and unpredictable whereas systemic toxicities are significant. Reported responses to conventional cytotoxic chemotherapy have also been disappointing, and the rarity of ACC had hampered the ability to undertake randomized clinical studies until the establishment of the First International Randomized Trial in Locally Advanced and Metastatic Adrenocortical Carcinoma. This yet-to-be reported study seeks to identify the most effective first- and second-line cytotoxic regimens. The past decade has also seen increasing research into the molecular pathogenesis of ACCs, with particular interest in the insulin-like growth factor signaling pathway. The widespread development of small molecule tyrosine kinase inhibitors in broader oncological practice is now allowing for the rational selection of targeted therapies to study in ACC. In this review, we discuss the currently available therapeutic options for patients with advanced ACC and detail the molecular rationale behind, and clinical evidence for, novel and emerging therapies.

Potent inhibitory effect of the cyclolignan picropodophyllin (PPP) on human adrenocortical carcinoma cells proliferation

Adrenocortical carcinoma (ACC) is a very aggressive tumor with a poor prognosis. Available treatments for this type of cancer are far from being satisfactory. The IGF signalling pathway represents an important mechanism for ACT growth and constitutes a relevant therapeutic target. We investigated the effect of picropodophyllin (PPP), a member of the cyclolignan family and a new inhibitor of IGF-1R, on proliferation of human adrenocortical cell lines H295R and SW-13. PPP inhibits proliferation and induces an important accumulation in G2/M phase and apoptosis of H295R and SW-13 cells. Our data suggest that PPP may be a promising candidate for drug development for adrenocortical carcinoma.

Combination mTOR and IGF-1R inhibition: phase I trial of everolimus and figitumumab in patients with advanced sarcomas and other solid tumors

PURPOSE

Preclinical models demonstrate synergistic antitumor activity with combination blockade of mTOR and IGF-1R signaling. We aimed to determine the safety, tolerability, and recommended phase II dose (RP2D) of the combination of figitumumab, a fully human IgG(2) anti-insulin-like growth factor-1 receptor (IGF-1R) monoclonal antibody (Pfizer) and the mTOR inhibitor, everolimus (Novartis). Pharmacokinetics and preliminary antitumor effects of the combination were evaluated.

EXPERIMENTAL DESIGN

Phase I trial in patients with advanced sarcomas and other solid tumors. Initial cohort combined full phase 2 dose figitumumab (20 mg/kg IV every 21 days) with full dose everolimus (10 mg orally once daily). Intercohort dose de-escalation was planned for unacceptable toxicities. Dose modifications were allowed beyond cycle 1.

RESULTS

No DLTs were observed in the initial cohort during cycle one, therefore full dose figitumumab and everolimus was declared the RP2D. In total, 21 patients were enrolled on study. Most toxicities were grade 1 or 2, and were similar to reported toxicities of the single agents. Mucositis was the most frequently observed grade 3 toxicity. Median time on study was 104 days (range 17-300). Of 18 patients evaluable for response, best response was partial response in 1 patient with malignant solitary fibrous tumor and, stable disease in 15 patients. There were no apparent pharmacokinetic interactions between everolimus and figitumumab.

CONCLUSIONS

Combination figitumumab plus everolimus at full doses appears safe and well tolerated with no unexpected toxicities. Dose reductions in everolimus may be required after prolonged drug administration. This regimen exhibits interesting antitumor activity warranting further investigation.

Therapy of adrenocortical cancer: present and future

Adrenocortical carcinoma is a rare endocrine malignancy with an estimated worldwide incidence of 0.5 - 2 per million/year. This neoplasm is characterized by a high risk of recurrence and a dismal prognosis owing to unsatisfactory overall survival. Surgery represents the cornerstone of adrenocortical carcinoma therapy, which can be associated to radiotherapy and adjuvant mitotane administration. In advanced cases, different chemotherapy regimens are used, but their relative efficacy is still unknown until the results of clinical trials under way will be published. Novel drugs have been recently developed based on the discovery of molecular pathways that trigger development and evolution of these tumors. More efficient treatments are widely expected in the future from these new targeted therapies as a hope of cure for patients affected with this aggressive malignancy.

Novel agents in the treatment of metastatic colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer death in the United States. Research has led to an explosion of knowledge into the molecular basis of CRC in the past decades. Numerous receptors and intracellular proteins have been identified and implicated in the growth and progression of metastatic CRC, thus creating novel targets for drug development. Many agents are under development and have begun to enter early and even later-stage clinical trials. Results of these agents have demonstrated some encouraging activity but in a small number of patients. Research into predictive biomarkers aims to select the patients who may benefit from these novel agents. This review will address several of these promising new agents, their potential relevance to CRC, results from early clinical studies, and their incorporation into future and ongoing CRC clinical trials. Clearly, there is an urgent need for new agents in this disease, but as we learned from the experience with epidermal growth factor receptor-targeted antibodies, patient selection will be increasingly be required for individualized therapy to become a reality in CRC.

Biological rationale and current clinical experience with anti-insulin-like growth factor 1 receptor monoclonal antibodies in treating sarcoma: twenty years from the bench to the bedside

Two decades have elapsed since insulin-like growth factor-1 receptor (IGF-1R) signaling was initially implicated in sarcoma biology to the first clinical experience of IGF-1R blockade in sarcoma. During these 21 years, the IGF pathway and its key mediator IGF-1R have been implicated in the genesis, growth, proliferation, metastasis, and resistance to conventional treatment in several sarcoma subtypes. In addition, IGF-1R has been validated, both in vitro and in vivo, as a target for the treatment of sarcoma. Several radiologic and clinical responses to IGF-1R monoclonal antibodies have been reported in Ewing sarcoma patients enrolled in early clinical studies. Furthermore, these therapies were well tolerated, and thus far severe toxicity has been rare. The early clinical evidence of antitumor activity has supported the initiation of various phase II clinical trials in Ewing and other sarcoma subtypes, the results of which are eagerly awaited, as well as studies assessing IGF-1R monoclonal antibodies in combination with traditional cytotoxics or other targeted therapies. Despite these encouraging results, not all patients benefit from IGF-1R inhibition and consequently there is an urgent need for the identification of predictive markers of response.

Figitumumab (CP-751,871) for cancer therapy

IMPORTANCE OF THE FIELD

Figitumumab is being developed as a highly potent and specific fully human IgG2 monoclonal antibody against the IGF Type 1 receptor (IGF-IR) for the treatment of cancer.

AREAS COVERED IN THIS REVIEW

This manuscript reviews the rationale, preclinical data and early clinical results of the figitumumab development program. Early trials were initiated in 2003 and initial reports appeared in 2006.

WHAT THE READER WILL GAIN

Figitumumab has an effective half life of approximately 20 days and has been generally well tolerated in clinical trials. Initial pharmacodynamic studies suggested that IGF-IR overexpression and increased bioactivity of IGFs constitute independent mechanisms of tumor sensitivity to figitumumab. Single-agent activity has been noted in Ewing's sarcoma and a recently completed proof-of-concept study suggested that figitumumab may be active in NSCLC.

TAKE HOME MESSAGE

The strong biologic rationale for IGF-IR targeting in multiple types of human cancer and the feasibility of combination with full doses of therapies that constitute the standard of care in a variety of oncology indications have justified an expanded clinical program in multiple areas of unmet medical need in oncology.

Emerging anticancer therapeutic targets and the cardiovascular system: is there cause for concern?

The race for a cure to cancer continues, fueled by unprecedented discoveries of fundamental biology underlying carcinogenesis and tumorigenesis. The expansion of the target list and tools to approach them is moving the oncology community extraordinarily rapidly to clinical trials, bringing new hope for cancer patients. This effort is also propelling biological discoveries in cardiovascular research, because many of the targets being explored in cancer play fundamental roles in the heart and vasculature. The combined efforts of cardiovascular and cancer biologists, along with clinical investigators in these fields, will be needed to understand how to safely exploit these efforts. Here, we discuss a few of the many research foci in oncology where we believe such collaboration will be particularly important.

Safety, pharmacokinetics, and preliminary activity of the anti-IGF-1R antibody figitumumab (CP-751,871) in patients with sarcoma and Ewing's sarcoma: a phase 1 expansion cohort study

BACKGROUND

Figitumumab is a fully human IgG2 monoclonal antibody targeting the insulin-like growth-factor-1 receptor (IGF-1R). Preclinical data suggest a dependence on insulin-like growth-factor signalling for sarcoma subtypes, including Ewing's sarcoma, and early reports show antitumour activity of IGF-1R-targeting drugs in these diseases.

METHODS

Between January, 2006, and August, 2008, patients with refractory, advanced sarcomas received figitumumab (20 mg/kg) in two single-stage expansion cohorts within a solid-tumour phase 1 trial. The first cohort (n=15) included patients with multiple sarcoma subtypes, age 18 years or older, and the second cohort (n=14) consisted of patients with refractory Ewing's sarcoma, age 9 years or older. The primary endpoint was to assess the safety and tolerability of figitumumab. Secondary endpoints included pharmacokinetic profiling and preliminary antitumour activity (best response by Response Evaluation Criteria in Solid Tumours [RECIST]) in evaluable patients who received at least one dose of medication. This study is registered with ClinicalTrials.gov, number NCT00474760.

FINDINGS

29 patients, 16 of whom had Ewing's sarcoma, were enrolled and received a total of 177 cycles of treatment (median 2, mean 6.1, range 1-24). Grade 3 deep venous thrombosis, grade 3 back pain, and grade 3 vomiting were each noted once in individual patients; one patient had grade 3 increases in aspartate aminotransferase and gammaglutamyltransferase concentrations. This patient also had grade 4 increases in alanine aminotransferase concentrations. The only other grade 4 adverse event was raised concentrations of uric acid, noted in one patient. Pharmacokinetics were comparable between patients with sarcoma and those with other solid tumours. 28 patients were assessed for response; two patients, both with Ewing's sarcoma, had objective responses (one complete response and one partial response) and eight patients had disease stabilisation (six with Ewing's sarcoma, one with synovial sarcoma, and one with fibrosarcoma) lasting 4 months or longer.

INTERPRETATION

Figitumumab is well tolerated and has antitumour activity in Ewing's sarcoma, warranting further investigation in this disease.

FUNDING

Pfizer Global Research and Development.