Akt/mTOR counteract the antitumor activities of cixutumumab, an anti-insulin-like growth factor I receptor monoclonal antibody

Molecular and immune targets in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer and often confers a good prognosis. Though surgery is the gold standard of treatment, unresectable or metastatic disease can necessitate systemic therapy. Of systemic agents, there is increasing interest in the use of immunotherapies and targeted therapy. Further study into the driver mutations in cSCC has identified opportunities for targeted therapy. In this review, we discuss both current and investigational immune and molecular targets of therapy for cSCC.

Unraveling the IGF System Interactome in Sarcomas Exploits Novel Therapeutic Options

Aberrant bioactivity of the insulin-like growth factor (IGF) system results in the development and progression of several pathologic conditions including cancer. Preclinical studies have shown promising anti-cancer therapeutic potentials for anti-IGF targeted therapies. However, a clear but limited clinical benefit was observed only in a minority of patients with sarcomas. The molecular complexity of the IGF system, which comprises multiple regulators and interactions with other cancer-related pathways, poses a major limitation in the use of anti-IGF agents and supports the need of combinatorial therapeutic strategies to better tackle this axis. In this review, we will initially highlight multiple mechanisms underlying IGF dysregulation in cancer and then focus on the impact of the IGF system and its complexity in sarcoma development and progression as well as response to anti-IGF therapies. We will also discuss the role of Ephrin receptors, Hippo pathway, BET proteins and CXCR4 signaling, as mediators of sarcoma malignancy and relevant interactors with the IGF system in tumor cells. A deeper understanding of these molecular interactions might provide the rationale for novel and more effective therapeutic combinations to treat sarcomas.

Mechanisms of drug resistance of pancreatic ductal adenocarcinoma at different levels

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death worldwide, and the mortality of patients with PDAC has not significantly decreased over the last few decades. Novel strategies exhibiting promising effects in preclinical or phase I/II clinical trials are often situated in an embarrassing condition owing to the disappointing results in phase III trials. The efficacy of the current therapeutic regimens is consistently compromised by the mechanisms of drug resistance at different levels, distinctly more intractable than several other solid tumours. In this review, the main mechanisms of drug resistance clinicians and investigators are dealing with during the exploitation and exploration of the anti-tumour effects of drugs in PDAC treatment are summarized. Corresponding measures to overcome these limitations are also discussed.

Insulin-like growth factor receptor signaling in tumorigenesis and drug resistance: a challenge for cancer therapy

Insulin-like growth factors (IGFs) play important roles in mammalian growth, development, aging, and diseases. Aberrant IGFs signaling may lead to malignant transformation and tumor progression, thus providing the rationale for targeting IGF axis in cancer. However, clinical trials of the type I IGF receptor (IGF-IR)-targeted agents have been largely disappointing. Accumulating evidence demonstrates that the IGF axis not only promotes tumorigenesis, but also confers resistance to standard treatments. Furthermore, there are diverse pathways leading to the resistance to IGF-IR-targeted therapy. Recent studies characterizing the complex IGFs signaling in cancer have raised hope to refine the strategies for targeting the IGF axis. This review highlights the biological activities of IGF-IR signaling in cancer and the contribution of IGF-IR to cytotoxic, endocrine, and molecular targeted therapies resistance. Moreover, we update the diverse mechanisms underlying resistance to IGF-IR-targeted agents and discuss the strategies for future development of the IGF axis-targeted agents.

Update of IGF-1 receptor inhibitor (ganitumab, dalotuzumab, cixutumumab, teprotumumab and figitumumab) effects on cancer therapy

BACKGROUND

Prognostic studies of insulin-like growth factor-1 receptor(IGF-1R) inhibitors in cancer therapy had promising results in infratests, which exhibited that IGF-1R signalling was crucial in cancer cells growth. However, the conclusion of later clinical trials revealed a dim future for IGF-1R inhibitors to treat cancer. We conducted this analysis to figure out how IGF-1R inhibitors acted in clinical cancer therapy.

MATERIAL AND METHODS

We searched up-to-date studies about the single agent of IGF-1R inhibitors or combination with other therapies in solid tumor. Five IGF-1R anti-agents were involved. The primary endpoint was progression-free survival (PFS). The secondary endpoint was overall survival (OS).

RESULT

17studies were enrolled. The results was not significant in overall survival (I2=37.1%, P=0.080, HR=1.08, 95% CI=0.97-1.21) and in progression-free survival (I2=0.0%, P=0.637, HR=1.05, 95% CI=0.98-1.12). OS for dalotuzumab, breast cancer, colorectal cancer, and PFS for prostate cancer even indicated harmful effects.

CONCLUSION

So far, anti-IGF-1R mono-antibodies did not make significant differences in solid tumor prognosis. On the contrary, pessimistic effects were shown in the dalotuzumab, breast cancer, colorectal cancer and prostate cancer subgroups. Further studies of IGF-1R anti-agents were needed, but unwarranted in unselected patients by predictive biomarkers.

mTOR co-targeting strategies for head and neck cancer therapy

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. There is an urgent need to develop effective therapeutic approaches to prevent and treat HNSCC. Recent deep sequencing of the HNSCC genomic landscape revealed a multiplicity and diversity of genetic alterations in this malignancy. Although a large variety of specific molecules were found altered in each individual tumor, they all participate in only a handful of driver signaling pathways. Among them, the PI3K/mTOR pathway is the most frequently activated, which plays a central role in cancer initiation and progression. In turn, targeting of mTOR may represent a precision therapeutic approach for HNSCC. Indeed, mTOR inhibition exerts potent anti-tumor activity in HNSCC experimental systems, and mTOR targeting clinical trials show encouraging results. However, advanced HNSCC patients may exhibit unpredictable drug resistance, and the analysis of its molecular basis suggests that co-targeting strategies may provide a more effective option. In addition, although counterintuitive, emerging evidence suggests that mTOR inhibition may enhance the anti-tumor immune response. These new findings raise the possibility that the combination of mTOR inhibitors and immune oncology agents may provide novel precision therapeutic options for HNSCC.

A Phase I Trial of the IGF-1R Antibody Ganitumab (AMG 479) in Combination with Everolimus (RAD001) and Panitumumab in Patients with Advanced Cancer

PURPOSE

This study evaluated the maximum tolerated dose or recommended phase II dose (RPTD) and safety and tolerability of the ganitumab and everolimus doublet regimen followed by the ganitumab, everolimus, and panitumumab triplet regimen.

MATERIALS AND METHODS

This was a standard 3 + 3 dose escalation trial. Doublet therapy consisted of ganitumab at 12 mg/kg every 2 weeks; doses of everolimus were adjusted according to dose-limiting toxicities (DLTs). Panitumumab at 4.8 mg/kg every 2 weeks was added to the RPTD of ganitumab and everolimus. DLTs were assessed in cycle 1; toxicity evaluation was closely monitored throughout treatment. Treatment continued until disease progression or undesirable toxicity. Pretreatment and on-treatment skin biopsies were collected to assess insulin-like growth factor 1 receptor and mammalian target of rapamycin (mTOR) target modulation.

RESULTS

Forty-three subjects were enrolled. In the doublet regimen, two DLTs were observed in cohort 1, no DLTs in cohort -1, and one in cohort -1B. The triplet combination was discontinued because of unacceptable toxicity. Common adverse events were thrombocytopenia/neutropenia, skin rash, mucositis, fatigue, and hyperglycemia. In the doublet regimen, two patients with refractory non-small cell lung cancer (NSCLC) achieved prolonged complete responses ranging from 18 to >60 months; one treatment-naïve patient with chondrosarcoma achieved prolonged stable disease >24 months. In dermal granulation tissue, the insulin-like growth factor receptor and mTOR pathways were potently and specifically inhibited by ganitumab and everolimus, respectively.

CONCLUSION

The triplet regimen of ganitumab, everolimus, and panitumumab was associated with unacceptable toxicity. However, the doublet of ganitumab at 12 mg/kg every 2 weeks and everolimus five times weekly had an acceptable safety profile and demonstrated notable clinical activity in patients with refractory NSCLC and sarcoma.

IMPLICATIONS FOR PRACTICE

This trial evaluated the maximum tolerated dose or recommended phase II dose and safety and tolerability of the ganitumab and everolimus doublet regimen followed by the ganitumab, everolimus, and panitumumab triplet regimen. Although the triplet regimen of ganitumab, everolimus, and panitumumab was associated with unacceptable toxicity, the doublet of ganitumab at 12 mg/kg every 2 weeks and everolimus at five times weekly had an acceptable safety profile and demonstrated notable clinical activity in patients with refractory non-small cell lung cancer and sarcoma.

Type I insulin-like growth factor receptor signaling in hematological malignancies

The insulin-like growth factor (IGF) signaling system plays key roles in the establishment and progression of different types of cancer. In agreement with this idea, substantial evidence has shown that the type I IGF receptor (IGF-IR) and its primary ligand IGF-I are important for maintaining the survival of malignant cells of hematopoietic origin. In this review, we discuss current understanding of the role of IGF-IR signaling in cancer with a focus on the hematological neoplasms. We also address the emergence of IGF-IR as a potential therapeutic target for the treatment of different types of cancer including plasma cell myeloma, leukemia, and lymphoma.

A smart copper-phthalocyanine framework nanoparticle for enhancing photodynamic therapy in hypoxic conditions by weakening cells through ATP depletion

Hypoxic tumor treatment by synergistic of photodynamic therapy and ATP deprivation.

Targeted therapy for soft tissue sarcomas in adolescents and young adults

Soft tissue sarcomas (STSs) are a heterogeneous group of tumors originating from the mesenchyme. Even though they affect individuals in all age groups, the prevalence of subtypes of STSs changes significantly from childhood through adolescence into adulthood. The mainstay of therapy is surgery, with or without the addition of chemotherapy and/or radiation therapy. These treatment modalities are associated, in many cases, with significant morbidity and, given the heterogeneity of tumor histologies encompassed by the term "STS", have not uniformly improved outcomes. Moreover, some subgroups of STSs appear to be more, and others less, responsive to conventional chemotherapy agents. Over the last two decades, our understanding of the biology of STSs is slowly increasing, allowing for the development of more targeted therapies. We review the new treatment modalities that have been tested on patients with STSs, with a special focus on adolescents and young adults, a group of patients that is often underrepresented in clinical trials and has not received the dedicated attention it deserves, given the significant differences in biology and treatment response in comparison to children and adults.

Overproduction of IGF-2 drives a subset of colorectal cancer cells, which specifically respond to an anti-IGF therapeutic antibody and combination therapies

Colorectal cancer (CRC) is a heterogeneous disease with a broad spectrum of genetic and epigenetic changes. A comprehensive molecular characterization of CRC by The Cancer Genome Atlas Network detected the overexpression of the insulin-like growth factor 2 (IGF2) gene, encoding a ligand for the insulin-like growth factor 1 receptor (IGF-1R), in a subset of CRC tumors. In this study, we investigated the oncogenic potential of IGF-2 in IGF2-overexpressing CRC models and the efficacy of MEDI-573, an IGF-1/2-neutralizing antibody. We found that a subset of CRC cell lines express high IGF-2 levels owing to an increased DNA copy number and hypermethylation in the H19 promoter of the IGF2 gene. MEDI-573 efficiently neutralized IGF-2 and induced apoptosis, which resulted in significant tumor growth inhibition in CRC mouse models that express high levels of IGF-2. These effects were specific to CRCs overexpressing IGF-2, as MEDI-573 did not affect the growth CRC cell lines with normal levels. Moreover, blockade of IGF-2 by MEDI-573 modulated other signaling pathways, suggesting combination therapies with inhibitors of these pathways. Indeed, in vivo efficacy was significantly enhanced when MEDI-573 was used in combination with trastuzumab, AZD2014 (dual mTORC1/2i), AZD5363 (AKTi) and selumetinib (AZD6244/ARRY-142886, MEK1/2i) or cetuximab. These results demonstrate that overexpressed IGF-2 is the major tumorigenic driver in a subset of CRCs and encourage testing of MEDI-573, alone and in combinations, in IGF2-overexpressing CRC patients.

Essential role of insulin-like growth factor 2 in resistance to histone deacetylase inhibitors

Histone deacetylase (HDAC) inhibitors (HDIs) are promising anticancer therapies and have been clinically used for the treatment of hematological malignancy. However, their efficacy in solid tumors is marginal and drug resistance hampers their further clinical utility. To develop novel strategies for the HDI-based anticancer therapeutics in non-small cell lung cancer (NSCLC), in the present study, we investigated the mechanisms underlying resistance to HDI treatment in NSCLC cells. We show the STAT3-mediated IGF2/IGF-1R signaling cascade as a key modulator for both acquired and primary HDI resistance. The treatment with HDI upregulated IGF2 transcription in NSCLC cells carrying intrinsic or acquired drug resistance via direct binding of STAT3 in IGF2 P3 and P4 promoters. Acetylated STAT3 emerged upon HDAC inhibition was protected from the proteasome-mediated degradation of STAT3 and functioned as a direct transcription factor for IGF2 expression. Genomic or pharmacological strategies targeting STAT3 diminished the HDI-induced IGF2 mRNA expression and overcame the resistance to HDI treatment in HDI-resistant NSCLC- or patient-derived tumor xenograft models. These findings provide new insights into the role of acetylated STAT3-mediated activation of IGF2 transcription in HDI resistance, suggesting IGF2 or STAT3 as novel targets to overcome HDI resistance in NSCLC.

Combination of mTOR and EGFR targeting in an orthotopic xenograft model of head and neck cancer

OBJECTIVES/HYPOTHESIS

Recent preclinical and clinical studies on head and neck squamous cell carcinoma (HNSCC) revealed synergistic effects when combining anti-EGFR agents with conventional chemotherapeutic drugs. Activation of the PI3-kinase/AKT/mTOR signaling pathway has been identified as an important mechanism implicated in tumor progression and resistance to EGFR inhibitors. The aim of this study was to investigate the effects of combining the mTOR inhibitor temsirolimus (Tem) with the anti-EGFR agent cetuximab (Cet) and conventional chemotherapeutic drugs (cisplatin and fluorouracil (C/F)) on an orthotopic model of HNSCC.

STUDY DESIGN

Preclinical in vivo study.

METHODS

We evaluated the anti-tumor efficacy (measured tumor volume) of Tem, Cet, and C/F, administered alone or in combination. Investigations were performed using a human HNSCC cell line, CAL33, injected into the mouth floor of nude mice.

RESULTS

As compared with the control, the combination of Tem and Cet led to the highest tumor inhibition and induced almost complete tumor growth arrest (P = 0.001). Tem significantly enhanced the impact of the Cet-C/F combination on tumor growth (P < 0.001). The highest inhibitory effects of treatments on cell proliferation (Ki67 labeling), MAPK (pP42/44 labeling), and PI3K/AKT/mTOR (pS6R labeling) signaling pathways were found with the Tem-Cet association.

CONCLUSION

In this orthotopic HNSCC model, the combination of Tem with Cet produced synergistic effects on tumor growth. These results were corroborated by a strong inhibition of both MAPK and PI3K-mTOR signaling pathways.

LEVEL OF EVIDENCE

N/A.

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.

Targeting the insulin-like growth factor receptor and Src signaling network for the treatment of non-small cell lung cancer

Background

Therapeutic interventions in the insulin-like growth factor receptor (IGF-1R) pathway were expected to provide clinical benefits; however, IGF-1R tyrosine kinase inhibitors (TKIs) have shown limited antitumor efficacy, and the mechanisms conveying resistance to these agents remain elusive.

Methods

The expression and activation of the IGF-1R and Src were assessed via the analysis of a publicly available dataset, as well as immunohistochemistry, Western blotting, RT-PCR, and in vitro kinase assays. The efficacy of IGF-1R TKIs alone or in combination with Src inhibitors was analyzed using MTT assays, colony formation assays, flow cytometric analysis, and xenograft tumor models.

Results

The co-activation of IGF-1R and Src was observed in multiple human NSCLC cell lines as well as in a tissue microarray (n = 353). The IGF-1R and Src proteins mutually phosphorylate on their autophosphorylation sites. In high-pSrc-expressing NSCLC cells, linsitinib treatment initially inactivated the IGF-1R pathway but led a Src-dependent reactivation of downstream effectors. In low-pSrc-expressing NSCLC cells, linsitinib treatment decreased the turnover of the IGF-1R and Src proteins, ultimately amplifying the reciprocal co-activation of IGF-1R and Src. Co-targeting IGF-1R and Src significantly suppressed the proliferation and tumor growth of both high-pSrc-expressing and low-pSrc-expressing NSCLC cells in vitro and in vivo and the growth of patient-derived tissues in vivo.

Conclusions

Reciprocal activation between Src and IGF-1R occurs in NSCLC. Src causes IGF-1R TKI resistance by acting as a key downstream modulator of the cross-talk between multiple membrane receptors. Targeting Src is a clinically applicable strategy to overcome resistance to IGF-1R TKIs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0392-3) contains supplementary material, which is available to authorized users.

Safety, tolerability, and pharmacokinetics of single and multiple doses of intravenous cixutumumab (IMC-A12), an inhibitor of the insulin-like growth factor-I receptor, administered weekly or every 2 weeks in patients with advanced solid tumors

BACKGROUND

Type 1 insulin-like growth factor receptor (IGF-IR) signaling is often dysregulated in cancer. Cixutumumab, a fully human IgG1 monoclonal antibody, blocks IGF-IR and inhibits downstream signaling. The current study determined the recommended dose, safety, and pharmacokinetic (PK) profile of weekly or every-2-week dosing of cixutumumab.

PATIENTS AND METHODS

Two open-label, multicenter phase I studies evaluated weekly (3-15 mg/kg) or every-2-weeks (6-15 mg/kg) dosing of cixutumumab in patients with advanced solid tumors. Serial blood samples for PK were collected up to 168-336 h (day 8-15) following the first administration of cixutumumab. Efficacy was evaluated as best overall tumor response.

RESULTS

A total of 24 and 16 patients were enrolled in the weekly and every-2-week dosing studies, respectively. Treatment-emergent adverse events (≥10%) included hyperglycemia, fatigue, anemia, nausea, and vomiting. Severe adverse events (AE) were infrequent; one serious AE (grade 3 electrocardiogram QT prolongation) was deemed possibly cixutumumab-related (10 mg/kg every-2-weeks). One death occurred due to disease progression (6 mg/kg weekly cohort). Maximum serum concentrations increased with dose. A maximum tolerated dose was not identified; pre-determined target serum minimum concentrations (60 μg/mL) were achieved with ≥6 mg/kg weekly and ≥10 mg/kg every-2-week dosing. Cixutumumab terminal elimination half-life is approximately a week (individual range, t1/2 = 4.58-9.33 days based upon 10 mg/kg every 2 weeks). Overall, stable disease was achieved in 25% of all patients.

CONCLUSIONS

Cixutumumab was associated with favorable safety and PK profiles. A dosing regimen of 10 mg/kg every 2 weeks was recommended for subsequent disease-focused clinical trials.

Evasion of anti-growth signaling: A key step in tumorigenesis and potential target for treatment and prophylaxis by natural compounds

The evasion of anti-growth signaling is an important characteristic of cancer cells. In order to continue to proliferate, cancer cells must somehow uncouple themselves from the many signals that exist to slow down cell growth. Here, we define the anti-growth signaling process, and review several important pathways involved in growth signaling: p53, phosphatase and tensin homolog (PTEN), retinoblastoma protein (Rb), Hippo, growth differentiation factor 15 (GDF15), AT-rich interactive domain 1A (ARID1A), Notch, insulin-like growth factor (IGF), and Krüppel-like factor 5 (KLF5) pathways. Aberrations in these processes in cancer cells involve mutations and thus the suppression of genes that prevent growth, as well as mutation and activation of genes involved in driving cell growth. Using these pathways as examples, we prioritize molecular targets that might be leveraged to promote anti-growth signaling in cancer cells. Interestingly, naturally occurring phytochemicals found in human diets (either singly or as mixtures) may promote anti-growth signaling, and do so without the potentially adverse effects associated with synthetic chemicals. We review examples of naturally occurring phytochemicals that may be applied to prevent cancer by antagonizing growth signaling, and propose one phytochemical for each pathway. These are: epigallocatechin-3-gallate (EGCG) for the Rb pathway, luteolin for p53, curcumin for PTEN, porphyrins for Hippo, genistein for GDF15, resveratrol for ARID1A, withaferin A for Notch and diguelin for the IGF1-receptor pathway. The coordination of anti-growth signaling and natural compound studies will provide insight into the future application of these compounds in the clinical setting.

HAP1 gene expression is associated with radiosensitivity in breast cancer cells

OBJECTIVES

The purpose of this study was to investigate the relationship between huntingtin-associated protein1 (HAP1) gene and radiation therapy of breast cancer cells.

METHODS

HAP1 gene was transfected into breast cancer MCF-7 cells, which was confirmed by quantitative reverse transcription-polymerase chain reaction analysis (qRT-PCR) and Western blot in vitro. The changes of cell radiosensitivity were assessed by colony formation assay. Apoptosis were examined by flow cytometry. The expressions of two radiation-induced genes were evaluated by Western blot. Tumor growth was investigated in nude mice xenograft models in vivo.

RESULTS

Our data showed that HAP1 gene expression was significantly increased in HAP1-transfected MCF-7 cells in comparison with the parental cells or negative control cells. The survival rate in MCF-7/HAP1 cells was significantly decreased after irradiation (0, 2, 4, 6, 8Gy), compared to cells in MCF-7 and MCF-7/Pb groups in vitro. HAP1 gene increased apoptosis in MCF-7 cells after irradiation. Additionally, the tumor volume and weight in MCF-7/HAP1+RT group were observably lower than in MCF-7/HAP1 group and MCF-7/Pb+RT group.

CONCLUSION

The present study indicated that HAP1 gene expression was related to the radiosensitivity of breast cancer cells and may play an important role in the regulation of cellular radiosensitivity.

Anti-IGF-1R monoclonal antibody inhibits the carcinogenicity activity of acquired trastuzumab-resistant SKOV3

Background

Antibody resistance, not only de novo but also acquired cases, usually exists and is related with lower survival rate and high risk of recurrence. Reversing the resistance often results in better clinical therapeutic effect. Previously, we established a trastuzumab-resistant ovarian cancer cell line, named as SKOV3-T, with lower HER2 and induced higher IGF-1R expression level to keep cell survival.

Methods

IGF-1R was identified important for SKOV3-T growth. Then, a novel anti-IGF-1R monoclonal antibody, named as LMAb1, was used to inhibit SKOV3-T in cell growth/proliferation, migration, clone formation and in vivo carcinogenicity.

Results

In both in vitro and in vivo assays, LMAb1 showed effective anti-tumor function, especially when being used in combination with trastuzumab, which was beneficial to longer survival time of mice as well as smaller tumor. It was also confirmed preliminarily that the mechanism of antibody might be to inhibit the activation of IGF-1R and downstream MAPK, AKT pathway transduction.

Conclusion

We achieved satisfactory anti-tumor activity using trastuzumab plus LMAb1 in trastuzumab-resistant ovarian cancer model. In similar cases, not only acquired but also de novo, good curative effect might be achieved using combined antibody therapy strategies.

Dual blockade of epidermal growth factor receptor and insulin-like growth factor receptor-1 signaling in metastatic pancreatic cancer: phase Ib and randomized phase II trial of gemcitabine, erlotinib, and cixutumumab versus gemcitabine plus erlotinib (SWOG S0727)

BACKGROUND

Targeting a single pathway in pancreatic adenocarcinoma (PC) is unlikely to affect its natural history. We tested the hypothesis that simulataneous targeting of the epidermal growth factor receptor (EGFR) and insulin-like growth factor receptor-1 (IGF-1R) pathways would significantly improve progression-free survival (PFS) by abrogating reciprocal signaling that promote drug resistance

METHODS

This was a phase Ib/II study testing cixutumumab, combined with erlotinib and gemcitabine (G) in patients with untreated metastatic PC. The control arm was erlotinib plus G. The primary end point was PFS. Eligibility included performance status 0/1 and normal fasting blood glucose. Polymorphisms in genes involved in G metabolism and in the EGFR pathway were also studied

RESULTS

The phase I results (n = 10) established the safety of cixutumumab 6 mg/kg/week intravenously, erlotinib 100 mg/day orally, and G 1000 mg/m(2) intravenously on days 1, 8, and 15 of a 28-day cycle. In the RP2 portion (116 eligible patients; median age, 63), the median PFS and overall survival (OS) were 3.6 and 7.0 months, respectively, on the cixutumumab arm, and 3.6 and 6.7 months, respecively, on the control arm. Major grades 3 and 4 toxicities with cixutumumab and control were elevation of transaminases, 12% and 6%, respectively; fatigue, 16% and 12%, respectively; gastrointestinal, 35% and 28%, respectively; neutropenia, 21% and 10%, respectively; and thrombocytopenia, 16% and 7%, respecively. Grade 3/4 hyperglycemia was seen in 16% of patients on cixutumumab. Grade 3 or 4 skin toxicity was similar in both arms of the study (< 5%). No significant differences in PFS by genotype were seen for any of the polymorphisms.

CONCLUSIONS

Adding the IGF-1R inhibitor cixutumumab to erlotinib and G did not lead to longer PFS or OS in metastatic PC.

MEDI-573, alone or in combination with mammalian target of rapamycin inhibitors, targets the insulin-like growth factor pathway in sarcomas

MEDI-573 is a human antibody that neutralizes insulin-like growth factor (IGF) I and IGFII. IGFs are overexpressed in multiple types of cancer; their overexpression is a potential mechanism for resistance to IGFI receptor (IGFIR)-targeting therapy. Effects of IGF on cell proliferation, differentiation, and survival are mediated through its binding to and activation of IGFIR or insulin receptor A (IR-A). In this study, we measured the mRNA levels of IGFI, IGFII, and IGFIR in human pediatric sarcoma xenografts, and protein levels in sarcoma cell lines. MEDI-573 potently inhibited in vitro proliferation of sarcoma cell lines, with Ewing sarcoma cell lines being the most sensitive. In addition, MEDI-573 inhibited IGFI- and IGFII-induced sarcoma cell proliferation in vitro. The effect of MEDI-573 on IGF signaling was also examined. Treatment with MEDI-573 markedly reduced levels of pIGFIR, pIR-A, and pAKT and significantly blocked IGFI- and IGFII-induced activation of the IGFIR and AKT pathways. MEDI-573 inhibited the growth of sarcoma xenografts in vivo and inhibition correlated with neutralization of IGFI and IGFII. Combination of MEDI-573 with either rapamycin or AZD2014, another mTOR inhibitor (mTORi), significantly enhanced the antitumor activity of MEDI-573, and this response correlated with modulation of AKT and mTOR signaling. In summary, sarcoma cells respond to autocrine or paracrine growth stimulation by IGFI and IGFII, and inhibition of IGFI and IGFII by MEDI-573 results in significant slowing of tumor growth rate in sarcoma models, particularly in Ewing sarcoma. These data provide evidence for the potential benefits of MEDI-573 and mTORi combinations in patients with Ewing sarcoma.

The combination of insulin-like growth factor receptor 1 (IGF1R) antibody cixutumumab and mitotane as a first-line therapy for patients with recurrent/metastatic adrenocortical carcinoma: a multi-institutional NCI-sponsored trial

Adrenocortical carcinoma (ACC) is an aggressive malignancy, which lacks an effective systemic treatment. Abnormal activation of insulin-like growth factor receptor 1 (IGF1R) has been frequently observed. Preclinical studies demonstrated that pharmacological inhibition of IGF1R signaling in ACC has antiproliferative effects. A previous phase I trial with an IGF1R inhibitor has demonstrated biological activity against ACC. The objective of this study is to assess the efficacy of the combination of the IGF1R inhibitor cixutumumab (IMC-A12) in association with mitotane as a first-line treatment for advanced/metastatic ACC. We conducted a multicenter, randomized double-arm phase II trial in patients with irresectable recurrent/metastatic ACC. The original protocol included two treatment groups: IMC-A12 + mitotane and mitotane as a single agent, after an initial single-arm phase for safety evaluation with IMC-A12 + mitotane. IMC-A12 was dosed at 10 mg/kg intravenously every 2 weeks. The starting dose for mitotane was 2 g daily, subsequently adjusted according to serum levels/symptoms. The primary endpoint was progression-free survival (PFS) according to RECIST (Response Evaluation Criteria in Solid Tumors). This study was terminated before the randomization phase due to slow accrual and limited efficacy. Twenty patients (13 males, 7 females) with a median age of 50.2 years (range 21.9-79.6) were enrolled for the single-arm phase. Therapeutic effects were observed in 8/20 patients, including one partial response and seven stable diseases. The median PFS was 6 weeks (range 2.66-48). Toxic events included two grade 4 (hyperglycemia and hyponatremia) and one grade 5 (multiorgan failure). Although the regimen demonstrated activity in some patients, the relatively low therapeutic efficacy precluded further studies with this combination of drugs.

Combination of anti-HER3 antibody MM-121/SAR256212 and cetuximab inhibits tumor growth in preclinical models of head and neck squamous cell carcinoma

The EGFR monoclonal antibody cetuximab is the only approved targeted agent for treating head and neck squamous cell carcinoma (HNSCC). Yet resistance to cetuximab has hindered its activity in this disease. Intrinsic or compensatory HER3 signaling may contribute to cetuximab resistance. To investigate the therapeutic benefit of combining MM-121/SAR256212, an anti-HER3 monoclonal antibody, with cetuximab in HNSCC, we initially screened 12 HNSCC cell lines for total and phosphorylated levels of the four HER receptors. We also investigated the combination of MM-121 with cetuximab in preclinical models of HNSCC. Our results revealed that HER3 is widely expressed and activated in HNSCC cell lines. MM-121 strongly inhibited phosphorylation of HER3 and AKT. When combined with cetuximab, MM-121 exerted a more potent antitumor activity through simultaneously inhibiting the activation of HER3 and EGFR and consequently the downstream PI3K/AKT and ERK pathways in vitro. Both high and low doses of MM-121 in combination with cetuximab significantly suppressed tumor growth in xenograft models and inhibited activations of HER3, EGFR, AKT, and ERK in vivo. Our work is the first report on this new combination in HNSCC and supports the concept that HER3 inhibition may play an important role in future therapy of HNSCC. Our results open the door for further mechanistic studies to better understand the role of HER3 in resistance to EGFR inhibitors in HNSCC.

Phase 2 trial of cixutumumab in children, adolescents, and young adults with refractory solid tumors: a report from the Children's Oncology Group

PURPOSE

This phase 2 study was designed to assess the efficacy of single agent cixutumumab (IMC-A12) and gain further information about associated toxicities and pharmacodynamics in children, adolescents, and young adults with recurrent or refractory solid tumors.

PATIENTS AND METHODS

Patients with relapsed or refractory solid tumors were treated with 9 mg/kg of cixutumumab as a 1-hour IV infusion once weekly. Strata included: osteosarcoma, Ewing sarcoma, rhabdomyosarcoma, neuroblastoma (evaluable disease), neuroblastoma (measurable disease), Wilms tumor, adrenocortical carcinoma, synovial sarcoma, hepatoblastoma, and retinoblastoma. Correlative studies in consenting patients included an assessment of c-peptide, IGFBP-3, IGF-1, IGF-2, hGH, and insulin in consenting patients.

RESULTS

One hundred sixteen patients with 114 eligible having a median age of 12 years (range, 2-30) were enrolled. Five patients achieved a partial response: 4/20 with neuroblastoma (evaluable only) and 1/20 with rhabdomyosarcoma. Fourteen patients had stable disease for a median of 10 cycles. Hematologic and non-hematologic toxicities were generally mild and infrequent. Serum IGF-1 and IGFBP-3 increased in response to therapy with cixutumumab.

CONCLUSION

Cixutumumab is well tolerated in children with refractory solid tumors. Limited objective single-agent activity of cixutumumab was observed; however, prolonged stable disease was observed in 15% of patients. Ongoing studies are evaluating the toxicity and benefit of cixutumumab in combination with other agents that inhibit the IGF pathway.

Insulin-like growth factor 1 pathway mutations and protein expression in resected non-small cell lung cancer

The purpose of this study was to characterize the prevalence of insulin-like growth factor 1 receptor (IGF1R) mutations, single nucleotide polymorphisms (SNP), and protein overexpression in surgically resected non-small cell lung cancers in relation to patient characteristics and prognosis. This retrospective study was conducted on 304 patients with non-small cell lung cancers who underwent curative pulmonary resection (median follow-up for surviving patients, 3.6 years). IGF1R gene alterations (n = 304) and protein expression (n = 181) were evaluated by polymerase chain reaction-based assays and immunohistochemistry, respectively. Membranous and cytoplasmic staining were analyzed separately. In an exploratory analysis, 1 silent mutation in exon 16 and 3 mutations in introns of the IGF1R gene comprising the tyrosine kinase domain were detected. Moreover, evaluating selected IGF1R SNPs, patients with adenocarcinomas and homozygous for the rs8038415 T-allele had a significantly better survival (P = .025) but no different disease-free survival. Regarding expression, membranous but not cytoplasmic IGF1R staining was higher in squamous cell carcinomas versus other histologies (P < .0001) and showed a trend to longer survival (P = .08). No association between SNP variations and protein expression was found. Membranous IGF1R protein expression is higher in squamous cell versus other histologies but does not correlate with prognosis. SNPs and mutations can be detected and may harbor prognostic value. These alterations may be of interest when evaluating the IGF1R as potential therapeutic target and should receive further research.

IGF-IR Targeted Therapy: Past, Present and Future

The IGF-I receptor (IGF-IR) has been studied as an anti-cancer target. However, monotherapy trials with IGF-IR targeted antibodies or with IGF-IR specific tyrosine kinase inhibitors have, overall, been very disappointing in the clinical setting. This review discusses potential reasons why IGF-I R targeted therapy fails to inhibit growth of human cancers. It has become clear that intracellular signaling pathways are highly interconnected and complex instead of being linear and simple. One of the most potent candidates for failure of IGF-IR targeted therapy is the insulin receptor isoform A (IR-A). Activation of the IR-A by insulin-like growth factor-II (IGF-II) bypasses the IGF-IR and its inhibition. Another factor may be that anti-cancer treatment may reduce IGF-IR expression. IGF-IR blocking drugs may also induce hyperglycemia and hyperinsulinemia, which may further stimulate cell growth. In addition, circulating IGF-IRs may reduce therapeutic effects of IGF-IR targeted therapy. Nevertheless, it is still possible that the IGF-IR may be a useful adjuvant or secondary target for the treatment of human cancers. Development of functional inhibitors that affect the IGF-IR and IR-A may be necessary to overcome resistance and to make IGF-IR targeted therapy successful. Drugs that modify alternative downstream effects of the IGF-IR, so called "biasing agonists," should also be considered.

Targeted therapies in development for non-small cell lung cancer

The iterative discovery in various malignancies during the past decades that a number of aberrant tumorigenic processes and signal transduction pathways are mediated by "druggable" protein kinases has led to a revolutionary change in drug development. In non-small cell lung cancer (NSCLC), the ErbB family of receptors (e.g., EGFR [epidermal growth factor receptor], HER2 [human epidermal growth factor receptor 2]), RAS (rat sarcoma gene), BRAF (v-raf murine sarcoma viral oncogene homolog B1), MAPK (mitogen-activated protein kinase) c-MET (c-mesenchymal-epithelial transition), FGFR (fibroblast growth factor receptor), DDR2 (discoidin domain receptor 2), PIK3CA (phosphatidylinositol-4,5-bisphosphate3-kinase, catalytic subunit alpha)), PTEN (phosphatase and tensin homolog), AKT (protein kinase B), ALK (anaplastic lym phoma kinase), RET (rearranged during transfection), ROS1 (reactive oxygen species 1) and EPH (erythropoietin-producing hepatoma) are key targets of various agents currently in clinical development. These oncogenic targets exert their selective growth advantage through various intercommunicating pathways, such as through RAS/RAF/MEK, phosphoinositide 3-kinase/AKT/mammalian target of rapamycin and SRC-signal transduction and transcription signaling. The recent clinical studies, EGFR tyrosine kinase inhibitors and crizotinib were considered as strongly effective targeted therapies in metastatic NSCLC. Currently, five molecular targeted agents were approved for treatment of advanced NSCLC: Gefitinib, erlotinib and afatinib for positive EGFR mutation, crizotinib for positive echinoderm microtubule-associated protein-like 4 (EML4)-ALK translocation and bevacizumab. Moreover, oncogenic mutant proteins are subject to regulation by protein trafficking pathways, specifically through the heat shock protein 90 system. Drug combinations affecting various nodes in these signaling and intracellular processes are predicted and demonstrated to be synergistic and advantageous in overcoming treatment resistance compared with monotherapy approaches. Understanding the role of the tumor microenvironment in the development and maintenance of the malignant phenotype provided additional therapeutic approaches as well. More recently, improved knowledge on tumor immunology has set the stage for promising immunotherapies in NSCLC. This review will focus on the rationale for the development of targeted therapies in NSCLC and the various strategies employed in preventing or overcoming the inevitable occurrence of treatment resistance.

Combating resistance to anti-IGFR antibody by targeting the integrin β3-Src pathway

BACKGROUND

Several phase II/III trials of anti-insulin-like growth factor 1 receptor (IGF-1R) monoclonal antibodies (mAbs) have shown limited efficacy. The mechanisms of resistance to IGF-1R mAb-based therapies and clinically applicable strategies for overcoming drug resistance are still undefined.

METHODS

IGF-1R mAb cixutumumab efficacy, alone or in combination with Src inhibitors, was evaluated in 10 human head and neck squamous cell carcinoma (HNSCC) and six non-small cell lung cancer (NSCLC) cell lines in vitro in two- or three-dimensional culture systems and in vivo in cell line- or patient-derived xenograft tumors in athymic nude mice (n = 6-9 per group). Cixutumumab-induced changes in cell signaling and IGF-1 binding to integrin β3 were determined by Western or ligand blotting, immunoprecipitation, immunofluorescence, and cell adhesion analyses and enzyme-linked immunosorbent assay. Data were analyzed by the two-sided Student t test or one-way analysis of variance.

RESULTS

Integrin β3-Src signaling cascade was activated by IGF-1 in HNSCC and NSCLC cells, when IGF-1 binding to IGF-1R was hampered by cixutumumab, resulting in Akt activation and cixutumumab resistance. Targeting integrin β3 or Src enhanced antitumor activity of cixutumumab in multiple cixutumumab-resistant cell lines and patient-derived tumors in vitro and in vivo. Mean tumor volume of mice cotreated with cixutumumab and integrin β3 siRNA was 133.7 mm(3) (95% confidence interval [CI] = 57.6 to 209.8 mm(3)) compared with those treated with cixutumumab (1472.5 mm(3); 95% CI = 1150.7 to 1794.3 mm(3); P < .001) or integrin β3 siRNA (903.2 mm(3); 95% CI = 636.1 to 1170.3 mm(3); P < .001) alone.

CONCLUSIONS

Increased Src activation through integrin ανβ3 confers considerable resistance against anti-IGF-1R mAb-based therapies in HNSCC and NSCLC cells. Dual targeting of the IGF-1R pathway and collateral integrin β3-Src signaling module may override this resistance.

IGF-1R as an anti-cancer target--trials and tribulations

Type I insulin-like growth factor receptor (IGF-1R) has long been recognized for its role in tumorigenesis and growth, but only recently have the tools for targeting the IGF pathway become available. More than 10 IGF/IGF-1R inhibitors have entered clinical trials, and these belong to three main classes: (1) monoclonal antibodies against IGF-1R, (2) monoclonal antibodies against IGF-1R ligands (IGF-1 and IGF-2), and (3) IGF-1R tyrosine kinase inhibitors. These IGF-1R-targeting agents share common effects on IGF-1R signaling but differ in mechanisms of action, spectrum of target inhibition, and pharmacological features. Clinical activity of IGF-1R inhibitors has been demonstrated with sustained responses in a small number of patients with select tumor types, such as Ewing sarcoma and thymoma. However, many large clinical trials involving patients with adult tumors, including non-small cell lung cancer, breast cancer, and pancreatic cancer, failed to show clinical benefit in the overall patient population. Possible reasons for failure include the complexity of the IGF-1R/insulin receptor system and parallel growth and survival pathways, as well as a lack of patient selection markers. While IGF-1R remains a valid target for selected tumor types, identification of predictive markers and rational combinations will be critical to success in future development.

Insulin-like growth factor 1 receptor as a therapeutic target in ewing sarcoma: lack of consistent upregulation or recurrent mutation and a review of the clinical trial literature

The insulin-like growth factor 1 receptor (IGF-1R) has been considered an important therapeutic target in Ewing sarcoma (ES), generating a need to identify the subset of patients most likely to respond to IGF-1R inhibitors. We assessed IGF-1R expression in ES cell lines and patient tumors to understand the variable clinical responses to anti-IGF-1R therapy. Using ligand-binding displacement, we measured between 13,000 and 40,000 receptors per cell in ES cell lines. We used ELISA to quantify IGF-1R in patient tumors, which expressed 4.8%  ± 3.7 to 20.0%  ± 0.2 of the levels in a positive control cell line overexpressing IGF-1R. Flow cytometry showed markedly reduced IGF-1R expression in ES cell lines compared to a standard positive control cell line. The IGF1R gene was sequenced in 47 ES tumor samples and 8 ES cell lines; only one tumor sample showed a nonsynonymous mutation, R1353H, in a region with low functional impact. Finally, we assessed IGF-1R pathway activity in the ES stem cell (ESSC) population, to characterize its potential for resistance to anti-IGF-1R therapy, using Luminex technology. We found no significant differences in IGF-1R pathway activity between ESSCs and the total cell population. Overall, our findings suggest that IGF-1R as a therapeutic target in this sarcoma may require reevaluation.

The mTOR pathway in lung cancer and implications for therapy and biomarker analysis

Mammalian target of rapamycin (mTOR) is a serine/threonine kinase that functions as a key regulatory protein in normal cell growth, survival, metabolism, development, and angiogenic pathways. Deregulation of these processes is a required hallmark of cancer, and dysregulation of mTOR signaling frequently occurs in a wide variety of malignancies, including lung cancer. Targeting of mTOR is thus an attractive strategy in the development of therapeutic agents against lung cancer. In this review, the mTOR-signaling pathway is described, highlighting opportunities for therapeutic intervention and biomarker analysis, and clinical trials in lung cancer including both non-small cell lung cancer and small cell lung cancer.