Ovarian cancer mortality ranks highest among all gynecological cancers with growth factor pathways playing an integral role in tumorigenesis, metastatic dissemination and therapeutic resistance. The human epidermal growth factor receptor (HER) and vascular endothelial growth factor receptor (VEGFR) are both overexpressed and/or aberrantly activated in subsets of ovarian tumors. While agents targeting either the HER or VEGF pathways alone have been investigated, the impact of these agents have not led to overall survival benefit in ovarian cancer. We tested the hypothesis that co-targeting HER and VEGFR would maximize anti-tumor efficacy at tolerable doses. To this end, ovarian cancer xenografts grown intraperitoneally in athymic nude mice were tested in response to AC480 (pan HER inhibitor, “HERi”), cediranib (pan VEGFR inhibitor “VEGFRi”), or BMS-690514 (combined HER/VEGFR inhibitor “EVRi”). EVRi was superior to both HERi and VEGFRi in terms of tumor growth, final tumor weight and progression-free survival. Correlative tumor studies employing phosphoproteomic antibody arrays revealed distinct agent-specific alterations, with EVRi inducing the greatest overall effect on growth factor signaling. These data suggest that simultaneous inhibition of HER and VEGFR may benefit select subsets of ovarian cancer tumors. To this end, we derived a novel HER/VEGF signature that correlated with poor overall survival in high-grade, late stage, serous ovarian cancer patient tumors.
Targeted therapy; EVRi; ovarian cancer; VEGF; HER; erbB; AC480; BMS-690514; cediranib
IGF-1R inhibitors arrived in the clinic accompanied by optimism based on preclinical activity of IGF-1R targeting, and recognition that low IGF bioactivity protects from cancer. This was tempered by concerns about toxicity to normal tissue IGF-1R and cross-reactivity with insulin receptor (InsR). In fact, toxicity is not a show-stopper; the key issue is efficacy. While IGF-1R inhibition induces responses as monotherapy in sarcomas and with chemotherapy or targeted agents in common cancers, negative Phase 2/3 trials in unselected patients prompted the cessation of several Pharma programs. Here, we review completed and on-going trials of IGF-1R antibodies, kinase inhibitors and ligand antibodies. We assess candidate bio-markers for patient selection, highlighting the potential predictive value of circulating IGFs/IGFBPs, the need for standardized assays for IGF-1R, and preclinical evidence that variant InsRs mediate resistance to IGF-1R antibodies. We review hypothesis-led and unbiased approaches to evaluate IGF-1R inhibitors with other agents, and stress the need to consider sequencing with chemotherapy. The last few years were a tough time for IGF-1R therapeutics, but also brought progress in understanding IGF biology. Even failed studies include patients who derived benefit; they should be investigated to identify features distinguishing the tumors and host environment of responders from non-responders. We emphasize the importance of incorporating biospecimen collection into trial design, and wording patient consents to allow post hoc analysis of trial material as new data become available. Such information represents the key to unlocking the potential of this approach, to inform the next generation of trials of IGF signalling inhibitors.
IGF; Type 1 IGF receptor; IGF-1R cancer therapy; Therapeutic antibody; Tyrosine kinase inhibitor; Predictive biomarker
In the era of targeted therapies, patients with gynecological malignancies have not yet been major beneficiaries of this new class of agents. This may reflect the fact that the main tumor types, ovarian, uterine and cervical cancers, are a highly heterogeneous group of cancers, with variable response to standard chemotherapies. This is also likely due to poor model development in which to study the diversity of these cancers. Cancer-derived cell lines fail to adequately recapitulate molecular hallmarks of specific cancer subsets and complex microenvironments, which may be critical for sensitivity to targeted therapies. Patient derived xenografts (PDX), using fresh human tumor without prior in vitro culture, combined with whole genome expression, gene copy number and sequencing analyses, could dramatically aid novel therapy development in gynecological malignancies. Gynecological tumors can be engrafted in immunodeficient mice with a high rate of success and within a reasonable time frame. The resulting PDX accurately recapitulate the patient’s tumour in histological, molecular and in vivo treatment response characteristics. Orthotopic PDX develop complications relevant for the clinic, such as ascites and bowel obstruction, providing opportunities for understanding the biology of these clinical problems. Thus, PDX have great promise for delivering improved understanding of gynecological malignancies, serve as better models for designing novel therapies and clinical trials and could underpin individualized, directed therapy for patients from whom PDX models have been established.
ovarian cancer; cervical cancer; model systems
New approaches to drug development are critically needed to lessen the time, cost, and resources necessary to identify and optimize active agents. Strategies to accelerate drug development include testing drugs earlier in the disease process, such as the neoadjuvant setting. The U.S. Food and Drug Administration (FDA) has issued guidance designed to accelerate drug approval through the use of neoadjuvant studies in which the surrogate short-term endpoint, pathologic response, can be used to identify active agents and shorten the time to approval of both efficacious drugs and biomarkers identifying patients most likely to respond. However, this approach has unique challenges. In particular, issues of patient safety are paramount, given the exposure of potentially curable patients to investigational agents with limited safety experience. Key components to safe drug development in the neoadjuvant setting include defining a study population at sufficiently poor prognosis with standard therapy to justify exposure to investigational agents, defining the extent and adequacy of safety data from phase I, detecting potentially harmful interactions between investigational and standard therapies, improving study designs, such as adaptive strategies, that limit patient exposure to ineffective agents, and intensifying safety monitoring in the course of the trial. The I-SPY2 trial is an example of a phase II neoadjuvant trial of novel agents for breast cancer in which these issues have been addressed, both in the design and conduct of the trial. These adaptations of phase II design enable acceleration of drug development by reducing time and cost to screen novel therapies for activity without compromising safety.
Insulin-like growth factor (IGF) signaling has been implicated in the resistance to hormonal therapy in breast cancer. Using a model of postmenopausal, estrogen-dependent breast cancer, we investigated the antitumor effects of the dual IGF-1R/InsR tyrosine kinase inhibitor BMS-754807 alone and in combination with letrozole or tamoxifen. BMS-754807 exhibited antiproliferative effects in vitro that synergized strongly in combination with letrozole or 4-hydroxytamoxifen and fulvestrant. Similarly, combined treatment of BMS-754807 with either tamoxifen or letrozole in vivo elicited tumor regressions not achieved by single-agent therapy. Notably, hormonal therapy enhanced the inhibition of IGF-1R/InsR without major side effects in animals. Microarray expression analysis revealed downregulation of cell-cycle control and survival pathways and upregulation of erbB in response to BMS-754807 plus hormonal therapy, particularly tamoxifen. Overall, these results offer a preclinical proof-of-concept for BMS-754807 as an antitumor agent in combination with hormonal therapies in hormone-sensitive breast cancer. Cooperative cell-cycle arrest, decreased proliferation, and enhanced promotion of apoptosis may contribute to antitumor effects to be gauged in future clinical investigations justified by our findings.
Ovarian cancer is the sixth most common cancer worldwide among women in developed countries and the most lethal of all gynecologic malignancies. There is a critical need for the introduction of targeted therapies to improve outcome. Epidemiological evidence suggests a critical role for steroid hormones in ovarian tumorigenesis. There is also increasing evidence from in vitro studies that estrogen, progestin, and androgen regulate proliferation and invasion of epithelial ovarian cancer cells. Limited clinical trials have shown modest response rates; however, they have consistently identified a small subset of patients that respond very well to endocrine therapy with few side effects. We propose that it is timely to perform additional well-designed trials that should include biomarkers of response.
Activation of EGFR can stimulate proliferative and survival signaling through mTOR. Preclinical data demonstrates synergistic activity of combined EGFR and mTOR inhibition. We undertook a phase I trial of temsirolimus (T, an mTOR inhibitor) and EKB-569 (E, an EGFR inhibitor) to determine the safety and tolerability.
The primary aim was to determine the maximally tolerated dose (MTD) of this combination in adults with solid tumors. Following the dose-escalation phase, (Cohort A), two subsequent cohorts were used to assess any pharmacokinetic (PK) interaction between the agents.
Forty eight patients were enrolled. The MTD of this combination was E, 35 mg daily and T, 30 mg on days 1–3 and 15–17 using a 28-day cycle. The most common toxicities were nausea, diarrhea, fatigue, anorexia, stomatitis, rash, anemia, neutropenia, thrombocytopenia, and hypertriglyceridemia. Sixteen patients (36%) had at least one grade 3 toxicity. The most frequent grade 3/4 toxicities were diarrhea, dehydration, and nausea and vomiting (19% each). No grade 5 events were seen. Four patients had a partial response and 15 had stable disease. Clinical benefit was seen across a range of tumor types and in all cohorts. PK analysis revealed no significant interaction between E and T.
This combination of agents is associated with tolerable toxicities at doses that induced responses. PK studies revealed no interaction between the drugs. Further investigations of this targeting strategy may be attractive in renal cell carcinoma, non-small cell lung cancer, alveolar sarcoma, and carcinoid tumor.
CCI-779; EKB-569; Temsirolimus; Phase I; Pharmacokinetics; Solid tumors
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.
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.
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).
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.
Real-time; qPCR; breast cancer; receptor; insulin; receptor; IGF Type 1; monoclonal antibodies; therapeutic use; protein kinase inhibitors
To improve the significance of insulin-like growth factor binding protein 5 (IGFBP-5) as a prognostic and potentially predictive marker in breast cancer patients.
Increased IGFBP-5 expression was identified in MCF-7 cells resistant (MCF-7R4) to the IGF-1R/InsR inhibitor, BMS-536924 and its role examined by targeted knockdown and overexpression in multiple experimental models. Protein expression of IGFBP-5 was measured by immunohistochemistry in a cohort of 76 breast cancer patients to examine correlative associations with invasive tumor fraction and outcome. The utility of a combined IGFBP-5/IGFBP-4 (BPR) expression ratio was applied to predict anti-IGF-1R/InsR response in a panel of breast cancer lines and outcome in multiple breast tumor cohorts.
IGFBP-5 knockdown decreased BMS-536924 resistance in MCF-7R4 cells, while IGFBP-5 overexpression in MCF-7 cells conferred resistance. When compared to pathologically normal reduction mammoplasty tissue, IGFBP-5 expression levels were upregulated in both invasive and histologically normal adjacent breast cancer tissue. In both univariate and multivariate modeling, metastasis-free survival (MFS), recurrence free survival (RFS), and overall survival (OS) were significantly associated with high IGFBP-5 expression. Prognostic power of IGFBP-5 was further increased with the addition of IGFBP-4 where tumors were ranked based upon IGFBP-5/IGFBP-4 expression ratio (BPR). Multiple breast cancer cohorts confirm that BPR (high vs. low) was a strong predictor of RFS and OS.
IGFBP-5 expression is a marker of poor outcome in breast cancer patients. An IGFBP-5/IGFBP-4 expression ratio may serve as a surrogate biomarker of IGF pathway activation and predict sensitivity to anti-IGF-1R-targeting.
IGFBP; breast cancer; poor outcome
To evaluate the efficacy and biological effects of the gemcitabine/tanespimycin combination in patients with advanced ovarian and peritoneal cancer. To assess the effect of tanespimycin on tumor cells, levels of the chaperone proteins HSP90 and HSP70 were examined in peripheral blood mononuclear cells (PBMC) and paired tumor biopsy lysates.
Two-cohort phase II clinical trial. Patients were grouped according to prior gemcitabine therapy. All participants received tanespimycin 154 mg/m2 on days 1 and 9 of cycle 1 and days 2 and 9 of subsequent cycles. Patients also received gemcitabine 750 mg/m2 on day 8 of the first treatment cycle and days 1 and 8 of subsequent cycles.
The tanespimycin/gemcitabine combination induced a partial response in 1 gemcitabine naïve patient and no partial responses in gemcitabine resistant patients. Stable disease was seen in 6 patients (2 gemcitabine naïve and 4 gemcitabine resistant). The most common toxicities were hematologic (anemia and neutropenia) as well as nausea and vomiting. Immunoblotting demonstrated limited upregulation of HSP70 but little or no change in levels of most client proteins in PBMC and paired tumor samples.
Although well tolerated, the tanespimycin/gemcitabine combination exhibited limited anticancer activity in patients with advanced epithelial ovarian and primary peritoneal carcinoma, perhaps because of failure to significantly downregulate the client proteins at clinically achievable exposures.
Phase I/II Trials; Tanespimycin; gemcitabine; ovarian cancer; peritoneal cancer; heat shock protein 90
Despite increasing evidence that precision therapy targeted to the molecular drivers of a cancer has the potential to improve clinical outcomes, high-grade epithelial ovarian cancer (OC) patients are currently treated without consideration of molecular phenotype, and predictive biomarkers that could better inform treatment remain unknown. Delivery of precision therapy requires improved integration of laboratory-based models and cutting-edge clinical research, with pre-clinical models predicting patient subsets that will benefit from a particular targeted therapeutic. Patient-derived xenografts (PDXs) are renewable tumor models engrafted in mice, generated from fresh human tumors without prior in vitro exposure. PDX models allow an invaluable assessment of tumor evolution and adaptive response to therapy. PDX models have been applied to pre-clinical drug testing and biomarker identification in a number of cancers including ovarian, pancreatic, breast, and prostate cancers. These models have been shown to be biologically stable and accurately reflect the patient tumor with regards to histopathology, gene expression, genetic mutations, and therapeutic response. However, pre-clinical analyses of molecularly annotated PDX models derived from high-grade serous ovarian cancer (HG-SOC) remain limited. In vivo response to conventional and/or targeted therapeutics has only been described for very small numbers of individual HG-SOC PDX in conjunction with sparse molecular annotation and patient outcome data. Recently, two consecutive panels of epithelial OC PDX correlate in vivo platinum response with molecular aberrations and source patient clinical outcomes. These studies underpin the value of PDX models to better direct chemotherapy and predict response to targeted therapy. Tumor heterogeneity, before and following treatment, as well as the importance of multiple molecular aberrations per individual tumor underscore some of the important issues addressed in PDX models.
ovarian cancer; patient-derived xenografts; pre-clinical models; targeted therapy; clinical trials
Resistance to chemotherapy is a major challenge in the treatment of ovarian/peritoneal cancer. One purported mechanism of topotecan resistance is the breast cancer resistance protein (BCRP) and P-glycoprotein (Pgp). We designed a phase II clinical trial evaluating the efficacy and adverse events profile of concomitant topotecan and lapatinib, a small molecule pan-erbB inhibitor that can block BCRP/Pgp efflux of topotecan.
Patients with platinum-refractory or resistant epithelial ovarian/peritoneal cancer were treated with topotecan 3.2 mg/m2 IV on Day 1, 8 and 15 and lapatinib 1250 mg PO daily, continuously in 28 day cycles. The primary endpoint was response rate. For correlative studies, archived tissue was assessed for expression of EGFR, HER2, HIF-1α, CD31, and BCRP.
Eighteen patients were enrolled and treated. Four experienced evidence of clinical benefit: one partial response and three with stable disease. Using a two-stage Simon design, the trial was stopped after the first stage due to insufficient activity. Grade 3+ and 4+ adverse events (AE) were experienced in 14 and 4 patients, respectively. The most common grade 3/4 AE were neutropenia (56%), thrombocytopenia (28%), and diarrhea (22%).
The combination of lapatinib plus topotecan for the treatment of platinum refractory/resistant epithelial ovarian cancer lacks sufficient activity to warrant further investigation. In particular, hematologic adverse events were substantial. Expression of correlative study markers did not reveal patterns of predicted benefit or toxicity. Disruption of erbB signaling and BCRP/Pgp efflux with lapatinib was insufficient for overcoming topotecan resistance, suggesting alternative mechanisms of resistance are involved.
To determine the maximum tolerated dose (MTD) and characterize the dose-limiting toxicities (DLT) of 17-AAG, gemcitabine and/or cisplatin. Levels of the proteins Hsp90, Hsp70 and ILK were measured in peripheral blood mononuclear cell (PMBC) lysates to assess the effects of 17-AAG.
Phase I dose-escalating trial using a “3+3” design performed in patients with advanced solid tumors. Once the MTD of gemcitabine + 17-AAG + cisplatin was determined, dose escalation of 17-AAG with constant doses of gemcitabine and cisplatin was attempted. After significant hematologic toxicity occurred, the protocol was amended to evaluate three cohorts: gemcitabine and 17-AAG; 17-AAG and cisplatin; and gemcitabine, 17-AAG and cisplatin with modified dosing.
The 39 patients enrolled were evaluable for toxicity and response. The MTD for cohort A was 154 mg/m2 of 17-AAG, 750 mg/m2 of gemcitabine, and 40 mg/m2 of cisplatin. In cohort A, DLTs were observed at the higher dose level and included neutropenia, hyperbilirubinemia, dehydration, GGT elevation, hyponatremia, nausea, vomiting, and thrombocytopenia. The MTD for cohort C was 154 mg/m2 of 17-AAG and 750 mg/m2 of gemcitabine, with one DLT observed (alkaline phosphatase elevation) observed. In cohort C, DLTs of thrombocytopenia, fever and dyspnea were seen at the higher dose level. The remaining cohorts were closed to accrual due to toxicity. Six patients experienced partial responses. Mean Hsp90 levels were decreased and levels of Hsp70 were increased compared to baseline.
17-AAG in combination with gemcitabine and cisplatin demonstrated antitumor activity, but significant hematologic toxicities were encountered. 17-AAG combined with gemcitabine is tolerable and has demonstrated evidence of activity at the MTD. The recommended phase II dose is defined as 154 mg/m2 of 17-AAG and 750 mg/m2 of gemcitabine, and is currently being investigated in phase II studies in ovarian and pancreatic cancers. There is no recommended phase II dose for the cisplatin-containing combinations.
17-allyaminogeldanamycin; Phase I; Heat shock protein 90; Cisplatin; Gemcitabine; Heat shock protein 70; ILK
Preclinical investigations have identified insulin-like growth factor (IGF) signaling as a key mechanism for cancer growth and resistance to clinically useful therapies in multiple tumor types, including breast cancer. Thus, agents targeting and blocking IGF signaling have promise in the treatment of solid tumors. To identify possible mechanisms of resistance to blocking the IGF pathway, we generated a cell line that was resistant to the IGF-1R/InsR benzimidazole inhibitors BMS-554417 and BMS-536924 and compared expression profiles of the parental and resistant cells lines using Affymetrix GeneChip Human Genome U133 arrays. Compared to MCF-7 cells, BCRP expression was increased 9-fold in MCF-7R4, which was confirmed by immunoblotting and was highly statistically significant (p= 7.13E-09). BCRP was also upregulated in an independently derived resistant cell line, MCF7 924R. MCF-7R4 cells had significantly lower intracellular accumulation of BMS-536924 compared to MCF-7 cells. Expression of BCRP in MCF-7 cells was sufficient to reduce sensitivity to BMS-536924. Furthermore, knockdown of BCRP in MCF-7R4 cells resensitized cells to BMS-536924. Four cell lines selected for resistance to the pyrrolotriazine IGF-1R/InsR inhibitor, BMS-754807 did not have upregulation of BCRP. These data suggest that benzimidazole IGF-1R/InsR inhibitors may select for upregulation and be effluxed by the ABC transporter BCRP, contributing to resistance. However, pyrrolotriazine IGF-1R/InsR inhibitors do not appear to be affected by this resistance mechanism.
BCRP; BMS-536924; Receptor; IGF Type I; tyrosine kinase inhibitor mechanism of resistance
Heat shock protein 90 (HSP90), which regulates the functions of multiple oncogenic signaling pathways, has emerged as a novel anticancer therapeutic target, and multiple small molecule HSP90 inhibitors are now in clinical trials. Although the effects of HSP90 inhibitors on oncogenic signaling pathways have been extensively studied, the impacts of these agents on tumor suppressor signaling pathways are currently unknown. Here, we have examined how HSP90 inhibitors affect LATS1 and the related protein LATS2, two kinases that relay antiproliferative signals in the Hippo tumor suppressor pathway. Both LATS1 and LATS2 were depleted from cells treated with the HSP90 inhibitors 17-allylamino-17-demethoxygeldanamycin (17-AAG), radicicol and PU-H71. Moreover, these kinases interacted with HSP90, and LATS1 isolated from 17-AAG-treated cells had reduced catalytic activity, thus demonstrating that the kinase is a bona fide HSP90 client. Importantly, LATS1 signaling was disrupted by 17-AAG in tumor cell lines in vitro and clinical ovarian cancers in vivo as shown by reduced levels of LATS1 and decreased phosphorylation of the LATS substrate YAP, an oncoprotein transcriptional coactivator that regulates genes involved in cell and tissue growth, including the CTGF gene. Consistent with the reduced YAP phosphorylation, there were increased levels of CTGF, a secreted protein that is implicated in tumor proliferation, metastasis, and angiogenesis. Taken together, these results identify LATS1 and LATS2 as novel HSP90 clients and demonstrate that HSP90 inhibitors can disrupt the LATS tumor suppressor pathway in human cancer cells.
Insulin-like growth factor 1 receptor signaling through upregulation of the stimulatory ligand IGF-II has been implicated in the pathogenesis of adrenocortical carcinoma. As there is a paucity of effective therapies, this dose expansion cohort of a phase 1 study was undertaken to determine the safety, tolerability, pharmacokinetics, and effects on endocrine markers of figitumumab in patients with adrenocortical carcinoma.
Figitumumab was administered on day 1 of each 21-day cycle at the maximal feasible dose (20 mg/kg) to a cohort of patients with metastatic, refractory adrenocortical carcinoma. Serum glucose, insulin, and growth hormone were measured pre-study, at cycle 4 and study end. Pharmacokinetic evaluation was performed during cycles 1 and 4.
Fourteen patients with adrenocortical carcinoma received 50 cycles of figitumumab at the 20 mg/kg. Treatment- related toxicities were generally mild and included hyperglycemia, nausea, fatigue, and anorexia. Single episodes of grade 4 hyperuricemia, proteinuria, and elevated gamma-glutamyltransferase were observed. Pharmacokinetics of figitumumab was comparable to patients with solid tumors other than adrenocortical carcinoma. Treatment with figitumumab increased serum insulin and growth hormone levels. Eight of 14 patients (57%) had stable disease.
The side effect profile and pharmacokinetics of figitumumab were similar in patients with adrenocortical carcinoma in comparison to patients with other solid tumors. While hyperglycemia was the most common adverse event, no clear patterns predicting severity were observed. The majority of patients receiving protocol therapy with single agent figitumumab experienced stability of disease, warranting further evaluation.
IGF-1R; Adrenocortical carcinoma; Monoclonal antibody; CP-751,871; Figitumumab
Edmonston vaccine strains of measles virus (MV) have shown significant antitumor activity in preclinical models of ovarian cancer. We engineered MV to express the marker peptide carcinoembryonic antigen (MVCEA virus) to also permit real-time monitoring of viral gene expression in tumors in the clinical setting. Patients with Taxol and platinum-refractory recurrent ovarian cancer and normal CEA levels were eligible for this phase I trial. Twenty-one patients were treated with MV-CEA i.p. every 4 weeks for up to 6 cycles at seven different dose levels (103–109 TCID50). We observed no dose-limiting toxicity, treatment-induced immunosuppression, development of anti-CEA antibodies, increase in anti-MV antibody titers, or virus shedding in urine or saliva. Dose-dependent CEA elevation in peritoneal fluid and serum was observed. Immunohistochemical analysis of patient tumor specimens revealed overexpression of measles receptor CD46 in 13 of 15 patients. Best objective response was dose-dependent stable disease in 14 of 21 patients with a median duration of 92.5 days (range, 54–277 days). Five patients had significant decreases in CA-125 levels. Median survival of patients on study was 12.15 months (DELnths; range, 1.3–38.4 months), comparing favorably to an expected median survival of 6 months (DELnth) in this patient population. Our findings indicate that i.p. administration of MV-CEA is well tolerated and results in dose-dependent biological activity in a cohort of heavily pretreated recurrent ovarian cancer patients.
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.
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.
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.
Figitumumab is well tolerated and has antitumour activity in Ewing’s sarcoma, warranting further investigation in this disease.
Pfizer Global Research and Development.
This phase 1 study was conducted to determine the recommended phase 2 dose of the selective insulin-like growth factor type 1 receptor (IGF-IR) inhibitor figitumumab (F, CP-751,871) given in combination with paclitaxel and carboplatin in patients with advanced solid tumors.
Patients received paclitaxel 200 mg/m2, carboplatin (area under the curve of 6), and F (0.05–20 mg/kg) q3 weeks for up to six cycles. Patients with objective response or stable disease were eligible to receive additional cycles of single agent F until disease progression. Safety, efficacy, pharmacokinetic, and pharmacodynamic endpoints were investigated.
Forty-two patients, including 35 with stages IIIB and IV non-small cell lung cancer (NSCLC), were enrolled in eight dose escalation cohorts. A maximum tolerated dose was not identified. Severe adverse events possibly related to F included fatigue, diarrhea, hyperglycemia, gamma glutamyl transpeptidase elevation, and thrombocytopenia (one case each). F plasma exposure parameters increased with dose. Fifteen objective responses (RECIST) were reported, including two complete responses in NSCLC and ovarian carcinoma. Notably, levels of bioactive IGF-1 seemed to influence response to treatment with objective responses in patients with a high baseline-free IGF-1 to IGF binding protein-3 ratio seen only in the 10 and 20 mg/kg dosing cohorts.
F was well tolerated in combination with paclitaxel and carboplatin. Based on its favorable safety, pharmacokinetic, and pharmacodynamic properties, the maximal feasible dose of 20 mg/kg has been selected for further investigation.
IGF-1R; Figitumumab; CP-751,871; NSCLC
The insulin receptor (IR) and insulin-like growth factor-1 (IGF1) receptor (IGF1R) are receptor tyrosine kinases that participate in mitogenic and antiapoptotic signaling in normal and neoplastic epithelia. In the present study, immunoblotting and RT-PCR demonstrated expression of IGF1R and IR isoform A in acute myelogenous leukemia (AML) cell lines as well as >80% of clinical AML isolates. Treatment with insulin enhanced signaling through the Akt and MEK1/2 pathways as well as survival of serum-starved AML cell lines. Conversely, treatment with BMS-536924, a dual IGF1R/IR kinase inhibitor that is undergoing preclinical testing, inhibited constitutive receptor phosphorylation as well as downstream signaling through MEK1/2 and Akt. These changes inhibited proliferation and, in some AML cell lines, induced apoptosis at submicromolar concentrations. Likewise, BMS-536924 inhibited leukemic colony formation in CD34+ clinical AML samples in vitro. Collectively, these results not only indicate that expression of IGF1R and IR isoform A is common in AML, but also demonstrate that interruption of signaling from these receptors inhibits proliferation in clinical AML isolates. Accordingly, further investigation of IGF1R/IR axis as a potential therapeutic target in AML appears warranted.
acute myelogenous leukemia; insulin receptor; insulin-like growth factor receptor; autocrine loop
The IGF pathway plays a major role in cancer cell proliferation, survival and resistance to antineoplastic therapies in many human malignancies. As such, interference with this pathway is the target of many investigational pharmacologic agents. Cixutumumab, a monoclonal antibody to IGF-1R, utilizes this concept. In this review, we summarize preclinical, pharmacologic and early clinical data regarding this agent and discuss the impact this drug might have on the future treatment of human cancers.
cixutumumab; IGF-1R; IMC-A12; monoclonal antibody
Many proliferative, invasive, and immune tolerance mechanisms that support normal human pregnancy are also exploited by malignancies to establish a nutrient supply and evade or edit the host immune response. In addition to the shared capacity for invading through normal tissues, both cancer cells and cells of the developing placenta create a microenvironment supportive of both immunologic privilege and angiogenesis. Systemic alterations in immunity are also detectable, particularly with respect to a helper T cell type 2 polarization evident in advanced cancers and midtrimester pregnancy. This review summarizes the similarities between growth and immune privilege in cancer and pregnancy and identifies areas for further investigation. Our PubMed search strategy included combinations of terms such as immune tolerance, pregnancy, cancer, cytokines, angiogenesis, and invasion. We did not place any restrictions on publication dates. The knowledge gained from analyzing similarities and differences between the physiologic state of pregnancy and the pathologic state of cancer could lead to identification of new potential targets for cancer therapeutic agents.
The breast cancer stem cell (BCSC) hypotheses suggest that breast cancer is derived from a single tumor-initiating cell with stem-like properties, but the source of these cells is unclear. We previously observed that induction of an immune response against an epithelial breast cancer led in vivo to the T cell-dependent outgrowth of a tumor, the cells of which had undergone epithelial to mesenchymal transition (EMT). The resulting mesenchymal tumor cells had a CD24−/loCD44+ phenotype, consistent with BCSCs. In the present study, we found that EMT was induced by CD8 T cells and the resulting tumors had characteristics of BCSCs, including potent tumorigenicity, ability to re-establish an epithelial tumor, and enhanced resistance to drugs and radiation. In contrast to the hierarchal cancer stem cell hypothesis which suggests that breast cancer arises from the transformation of a resident tissue stem cell, our results show that EMT can produce the BCSC phenotype. These findings have several important implications related to disease progression and relapse.
EMT; breast cancer stem cells; generation in vivo; chemoresistance; radioresistance
Malignant melanoma presents a substantial clinical challenge. Current diagnostic methods are limited in their ability to diagnose early disease and accurately predict individual risk of disease progression and outcome. The lack of adequate approaches to properly define disease subgroups precludes rational treatment design and selection. Better tools are urgently needed to provide more accurate and personalized melanoma patient management. Recent progress in the understanding of the molecular aberrations that underlie melanoma oncogenesis will likely advance the diagnosis, prognosis, and treatment of melanoma. The emerging pattern of molecular complexity in melanoma tumors mirrors the clinical diversity of the disease and highlights the notion that melanoma, like other cancers, is not a single disease but a heterogeneous group of disorders that arise from complex molecular changes. Understanding of molecular aberrations involving important cellular processes, such as cellular signaling networks, cell cycle regulation, and cell death, will be essential for better diagnosis, accurate assessment of prognosis, and rational design of effective therapeutics. Defining an individual patient’s unique tumor characteristics may lead to personalized prediction of outcomes and selection of therapy. We review the emerging molecular landscape of melanoma and its implications for better management of patients with melanoma.