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

Proteomic analysis of combined IGF1 receptor targeted therapy and chemotherapy identifies signatures associated with survival in breast cancer patients

Clinical, epidemiological and experimental data identified the insulin-like growth factor-1 receptor (IGF1R) as a candidate therapeutic target in oncology. While this paradigm is based on well-established biological facts, including the potent anti-apoptotic and cell survival capabilities of the receptor, most Phase III clinical trials designed to target the IGF1R led to disappointing results. The present study was aimed at evaluating the hypothesis that combined treatment composed of selective IGF1R inhibitor along with classical chemotherapy might be more effective than individual monotherapies in breast cancer treatment. Analyses included comprehensive measurements of the synergism achieved by various combination regimens using the CompuSyn software. In addition, proteomic analyses were conducted to identify the proteins involved in the synergistic killing effect at a global level. Data presented here demonstrates that co-treatment of IGF1R inhibitor along with chemotherapeutic drugs markedly improves the therapeutic efficiency in breast cancer cells. Of clinical relevance, our analyses indicate that high IGF1R baseline expression may serve as a predictive biomarker for IGF1R targeted therapy. In addition, we identified a ten-genes signature with potential predictive value. In conclusion, the use of a series of bioinformatics tools shed light on some of the biological pathways that might be responsible for synergysm in cancer therapy.

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

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

Antiproliferative and apoptotic effects of a specific anti-insulin-like growth factor I receptor single chain antibody on breast cancer cells

Insulin-like growth factor I receptor (IGF-IR) is expressed on breast cancer cells and involves in metastasis, survival, and proliferation. Currently, application of IGF-IR-targeting monoclonal antibodies (mAbs), alone or in combination with other drugs, is a promising strategy for breast cancer therapy. Single-chain fragment variable (scFv) antibodies have been introduced as appropriate tools for tumor-targeting purposes because of their advantages over whole antibodies. In the present study, we employed a naïve phage library and isolated scFvs against a specific epitope from extracellular domain of IGF-IR by panning process. The selected scFvs were further characterized using polyclonal and monoclonal phage ELISA, soluble monoclonal ELISA, and colony PCR and sequencing. Antiproliferative and apoptotic effects of selected scFv antibodies on breast cancer cell lines were also evaluated by MTT and Annexin V/PI assays. The results of ELISA indicated specific reactions of the isolated scFvs against the IGF-IR peptide, and analyses of PCR product and sequencing confirmed the presence of full length V_H and Vκ inserts. Treatment of MCF7 and SKBR3 cells with anti-IGF-IR scFv led to a significant growth inhibition. The results also showed that scFv treatment significantly augmented trastuzumab growth inhibitory effects on SKBR3 cells. The percentage of the apoptotic MCF7 and SKBR3 cells after 24-h treatment with scFv was 39 and 30.70 %, respectively. Twenty-four-hour treatment with scFv in combination with trastuzumab resulted in 44.75 % apoptosis of SKBR3 cells. Taken together, our results demonstrate that the targeting of IGF-IR by scFv can be an effective strategy in the treatment of breast cancer and provide further evidence for effectiveness of dual targeting of HER2 and IGF-IR in breast cancer therapy.

An Open-Label, Multicenter, Randomized, Phase II Study of Cisplatin and Pemetrexed With or Without Cixutumumab (IMC-A12) as a First-Line Therapy in Patients With Advanced Nonsquamous Non-Small Cell Lung Cancer

INTRODUCTION

Type 1 insulin-like growth factor receptor is deregulated in solid tumors. Cixutumumab, a monoclonal antibody that inhibits the activity of type 1 insulin-like growth factor receptor, was investigated in combination with pemetrexed/cisplatin in the frontline setting.

METHODS

In this open-label, phase II study, patients with stage IV nonsquamous NSCLC and a performance status of 0 to 1 were randomized (1:1) to receive 20 mg/kg cixutumumab, 500 mg/m² pemetrexed, and 75 mg/m² cisplatin (cixutumumab [n = 87]) or pemetrexed and cisplatin (control [n = 85]). Eligible patients received pemetrexed-based maintenance therapy with cixutumumab (cixutumumab arm) or without it (control arm). The primary end point was progression-free survival. Secondary end points assessed overall survival, objective response rate, and safety. Survival was analyzed by the Kaplan-Meier method and Cox proportional hazard model. Exploratory correlative analyses were also performed.

RESULTS

The mean age of the intent-to-treat population (n = 172) was 59 years (range 32-83). Median progression-free survival was 5.45 months with cixutumumab versus 5.22 months in the control (hazard ratio = 1.15, 95% confidence interval: 0.81-1.61; p = 0.44). Median overall survival was 11.33 months with cixutumumab versus 10.38 months in the control (hazard ratio = 0.93, 95% confidence interval: 0.64-1.36). Objective response rate did not differ between treatments (p = 0.338). Grade 3 or 4 hyperglycemia occurred at a higher rate with cixutumumab than in the control (9.4% versus 1.2%). One death possibly related to cixutumumab occurred.

CONCLUSIONS

Efficacy was not improved in patients with nonsquamous NSCLC when cixutumumab was added to pemetrexed/cisplatin. Combination therapy was well tolerated and no new safety concerns were reported.

Semi-Mechanism-Based Pharmacokinetic/Pharmacodynamic Model for the Combination Use of Dexamethasone and Gemcitabine in Breast Cancer

Our study aimed at the investigation of in vivo anticancer effect of the combination use of dexamethasone (DEX) and gemcitabine (GM) as well as the development of pharmacokinetic/pharmacodynamic (PK/PD) models in MCF-7 xenograft model. Further, simulations were conducted to optimize doses and administration schedules. The inhibitory effect of different doses and administration schedules were investigated in MCF-7 xenograft model. Semi-mechanism-based PK/PD models were established based on the preclinical data to characterize the relationship between plasma concentration and the time course of the drug response quantitatively. The PK/PD models were further applied to predict and optimize doses and administration schedules, which would lead to tumor stasis by the end of the treatment. Synergistic effect was observed in the PD study in vivo and further confirmed by the estimated combination index ψ obtained from PK/PD models. The optimum dose regimen was selected as DEX 2 mg/kg, qd and GM 10 mg/kg, q2d based on the simulation results. In summary, the PD interaction between DEX and GM was demonstrated as synergism by both experimental results and modeling approach. Dosage regimens were optimized as predicted by modeling and simulations, which would provide reference for preclinical study and translational research as well.

The emergence of targeted drugs in breast cancer to prevent resistance to endocrine treatment and chemotherapy

INTRODUCTION

Deregulated signaling pathways are associated with resistance to chemotherapy and endocrine treatment, providing a rationale for the implementation of novel targeted therapies in breast cancer therapy. Key molecules targeted therapeutically in ongoing clinical breast cancer trials are phosphoinositide 3-kinase-Akt-mammalian target of rapamycin (mTOR), Src, insulin-like growth factor 1 receptor, heat shock protein-90, histone deacetylases, cyclin-dependent kinases (CDKs), Notch and human epidermal growth factor receptors (HERs).

AREAS COVERED

This review provides an overview of novel targeted agents currently explored in clinical breast cancer trials and registered in ClinicalTrials.gov. The main focus will be on their ability to prevent or reverse endocrine resistance and chemoresistance in breast cancer.

EXPERT OPINION

HER2 targeted agents have extended survival substantially, both in the adjuvant and metastatic setting, pointing to a crucial dependency on this pathway in HER2-amplified breast cancer, including drug resistance reversal. While data on mTOR inhibitors are encouraging and preliminary results on CDK4/6 and Src inhibitors exciting, so far other targeted agents have been of limited benefit when added in concert with conventional therapies. Future clinical trials should systematically explore biomarkers and defects in functional gene cascades to identify relevant biological mechanisms to be targeted therapeutically in breast cancer.

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.