TAK-264 (MLN0264) in Previously Treated Asian Patients with Advanced Gastrointestinal Carcinoma Expressing Guanylyl Cyclase C: Results from an Open-Label, Non-randomized Phase 1 Study

PURPOSE

This phase 1 dose-escalation portion of the study evaluated the safety, pharmacokinetics (PK), and antitumor activity of TAK-264 in Asian patients with advanced gastrointestinal (GI) carcinoma or metastatic or recurrent gastric or gastroesophageal junction adenocarcinoma expressing guanylyl cyclase C (GCC).

MATERIALS AND METHODS

Adult patients with advanced GI malignancies expressing GCC (H-score ≥ 10) received TAK-264 on day 1 of 3-week cycles as 30-minute intravenous infusions for up to 1 year or until disease progression or unacceptable toxicity. The primary objectives were to evaluate the safety profile including dose-limiting toxicities (DLTs) during cycle 1, determine the maximum tolerated dose (MTD), and characterize the PK profile of TAK-264.

RESULTS

Twelve patients were enrolled and treated with 1.2 mg/kg (n=3), 1.5 mg/kg (n=3), or 1.8 mg/kg TAK-264 (n=6). Median number of treatment cycles received was two (range, 1 to 10). None of the patients experienced a DLT and the MTD was not determined. Ten patients (83%) experienced adverse events (AEs). The most common were neutropenia, anorexia, and nausea (each reported by four patients). Five patients (42%) experienced grade ≥ 3 AEs consisting of tumor hemorrhage and hypertension, ascites, adrenal insufficiency, neutropenia and asthenia. Serum exposure to TAK-264 increased proportionally with the dose and the median half-life was approximately 5.5-6.6 days. No patients experienced an objective response.

CONCLUSION

TAK-264 demonstrated a manageable safety profile with limited antitumor activity consistent with studies conducted in Western patients with advanced GI malignancies. TAK-264 exposure increased proportionally with the dose.

Evaluation of TAK-264, an Antibody-Drug Conjugate in Pancreatic Cancer Cell Lines and Patient-Derived Xenograft Models

BACKGROUND

Antibody-drug conjugates (ADCs) are an emerging technology consisting of an antibody, linker, and toxic agent, which have the potential to offer a targeted therapeutic approach. A novel target recently explored for the treatment of pancreatic cancer is guanylyl cyclase C (GCC). The objective of this study was to determine the anti-tumorigenic activity of TAK-264, an investigational ADC consisting of an antibody targeting GCC linked to a monomethyl auristatin E payload via a peptide linker.

METHODS

The antiproliferative effects of TAK-264 assessed in a panel of eleven pancreatic cancer cell lines. Additionally, ten unique pancreatic ductal adenocarcinoma cancer patient-derived xenograft models were treated with TAK-264 and the efficacy was determined. Baseline levels of GCC were analyzed on PDX models and cell lines. Immunoblotting was performed to evaluate the effects of TAK-264 on downstream effectors.

RESULTS

GCC protein expression was analyzed by immunoblotting in both normal and tumor tissue; marked increase in GCC expression was observed in tumor tissue. The in vitro experiments demonstrated a range of responses to TAK-264. Eight of the ten PDAC PDX models treated with TAK-264 demonstrated a statistically significant tumor growth inhibition. Immunoblotting demonstrated an increase in phosphorylated-HistoneH3 in both responsive and less responsive cell lines and PDAC PDX models treated with TAK-264. There was no correlation between baseline levels of GCC and response in either PDX or cell line models.

CONCLUSION

TAK-264 has shown suppression activity in pancreatic cancer cell lines and in pancreatic PDX models. These findings support further investigation of ADC targeting GCC.

Abstract B050: Evaluation of TAK-264, a novel antibody-drug conjugate in pancreatic cancer cell lines and patient-derived xenograft models

Background: Antibody-drug conjugates (ADCs) are an emerging technology consisting of antibody, linker, and toxic agent, which have the potential to offer a more targeted therapeutic approach than standard chemotherapy regimens. ADCs selectively bind to antigens expressed in tumor environments. An emerging target for the treatment of pancreatic cancer is guanylyl cyclase C (GCC). GCC is a transmembrane G protein receptor found on the apical surface of intestinal enterocytes. It plays an important role in GI homeostasis. GCC is highly expressed in various colorectal carcinomas as well as adenocarcinomas of the upper GI tract. The objective of this study was to determine the antitumorigenic activity of TAK-264, an investigational ADC that targets GCC. Experimental Procedures: The antiproliferative effects of TAK-264 were assessed in a panel of eleven pancreatic cancer cell lines with various molecular backgrounds. Additionally, ten unique pancreatic ductal adenocarcinoma (PDAC) cancer patient-derived xenograft (PDX) models were treated with TAK-264 and the efficacy was determined. Tumor size was evaluated twice per week by caliper measurements. Sensitivity to TAK-264 was defined based on tumor growth inhibition that was statistically significant when compared to the vehicle control. Baseline levels of GCC were analyzed by IHC/immunoblotting and RT-PCR on PDX models and cell lines. Immunoblotting was performed to evaluate the effects of TAK-264 on downstream effectors. Results: GCC protein expression was analyzed by immunoblotting in normal versus tumor tissue; a marked increase in GCC expression was observed in tumor tissue when compared to matching normal tissue. The in vitro experiments demonstrated a range of responses to TAK-264 in an SRB assay. Eight of the ten PDAC PDX models demonstrated a statistically significant tumor growth inhibition when compared to the vehicle control. Immunoblotting demonstrated an increase in phosphorylated-Histone-H3 in two cell lines and in the PDAC PDX models treated with TAK-264, indicating a DNA damage response. The analysis of GCC protein expression in normal versus tumor tissue has shown a marked increase in GCC expression in tumor tissue when compared to matching normal tissue. There was no correlation between baseline levels of GCC and response to TAK-264 in either PDX or cell line models. Conclusions: TAK-264, an ADC targeting GCC, has good growth suppression activity in pancreatic cancer cell lines and in pancreatic PDX models. These findings support a hypothesis that further investigation of ADC targeting GCC may lead to novel therapeutic modalities for pancreatic cancer.

Citation Format: Anna R. Schreiber, Anna Nguyen, Stacey M. Bagby, Betelehem Yacob, Kevin Quackenbush, Joe L. Guy, Thomas Crowell, Bradley Stringer, Hadi Danaee, Thea Kalebic, Wells A. Messersmith, John J. Arcaroli, Todd M. Pitts. Evaluation of TAK-264, a novel antibody-drug conjugate in pancreatic cancer cell lines and patient-derived xenograft models [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B050.

Consistent expression of guanylyl cyclase-C in primary and metastatic gastrointestinal cancers

BACKGROUND

The transmembrane receptor guanylate cyclase-C (GCC) has been found to be expressed in colorectal cancers. However, limited data are available on GCC protein expression in non-colorectal gastrointestinal tumors and few studies have reported whether GCC protein expression was consistently preserved in synchronous primary and metastatic cancer tissues.

METHODS

GCC protein status was assessed by immunohistochemistry in tumor specimens from individuals (n = 627) with gastrointestinal tumors, including esophageal (n = 130), gastric (n = 276), pancreatic (n = 136), and colorectal (n = 85) primary and metastatic tumors. Tissue specimens consisted of tissue microarrays containing esophageal, gastric, pancreatic tumors, and whole-slide tissue sections from colorectal cancer patients with matching primary and metastatic tumors.

RESULT

Among the evaluated esophageal, gastric, and pancreatic tumors, the frequency of GCC positivity at the protein level ranged from 59% to 68%. GCC was consistently expressed in primary and matched/synchronous metastatic lesions of colorectal cancer tissues derived from the same patients.

CONCLUSION

This observational study demonstrated the protein expression of GCC across various gastrointestinal malignancies. In all cancer histotypes, GCC protein localization was observed predominantly in the cytoplasm compared to the membrane region of tumor cells. Consistent immunohistochemistry detection of GCC protein expression in primary colorectal cancers and in their matched liver metastases suggests that the expression of GCC is maintained throughout the process of tumor progression and formation of metastatic disease.

A phase II study of antibody-drug conjugate, TAK-264 (MLN0264) in previously treated patients with advanced or metastatic pancreatic adenocarcinoma expressing guanylyl cyclase C

Background This phase II open-label, multicenter study evaluated the efficacy, safety, and tolerability of TAK-264 in previously treated patients with advanced or metastatic pancreatic adenocarcinoma expressing guanylyl cyclase C (GCC). Methods Patients with advanced or metastatic pancreatic adenocarcinoma expressing GCC (H-score ≥ 10) received TAK-264 1.8 mg/kg on day 1 of a 21-day cycle as a 30-min intravenous infusion for up to 1 year or until disease progression or unacceptable toxicity. The primary objective was overall response rate (ORR [complete response + partial response (PR)]). Secondary objectives included evaluations of the safety and pharmacokinetic profile of TAK-264 (NCT02202785). Results 43 patients were enrolled and treated with 1.8 mg/kg TAK-264: 11, 15, and 17 patients with low, intermediate, and high GCC expression, respectively. Median number of treatment cycles received was two (range 1-10). The ORR was 3%, including one patient with intermediate GCC expression who achieved a PR. All patients experienced ≥1 adverse events (AE). The majority of patients experienced grade 1/2 AEs affecting the gastrointestinal tract. Fifteen (35%) patients experienced ≥grade 3 drug-related AEs; five (12%) patients had a serious AE. The most common (≥10% of patients) all-grade drug-related AEs were nausea (33%), fatigue (28%), neutropenia (23%), decreased appetite (23%), vomiting (16%), asthenia (16%), and alopecia (14%). Conclusions TAK-264 demonstrated a manageable safety profile; however, the low efficacy of TAK-264 observed in this study did not support further clinical investigation.

Phase II study of the antibody-drug conjugate TAK-264 (MLN0264) in patients with metastatic or recurrent adenocarcinoma of the stomach or gastroesophageal junction expressing guanylyl cyclase C

Background The first-in-class antibody-drug conjugate TAK-264 (formerly MLN0264) consists of an antibody targeting guanylyl cyclase C (GCC) conjugated to monomethyl auristatin E (MMAE) via a peptide linker. This phase II study evaluated the efficacy and safety of TAK-264 in patients with adenocarcinoma of the stomach or gastroesophageal junction expressing GCC, who had progressed on ≥1 line of prior therapy. Methods This study used a two-stage design, with an interim analysis conducted after stage I to determine whether to continue to stage II or discontinue on the grounds of futility. Adult patients with gastric and gastroesophageal junction adenocarcinoma expressing low, intermediate, or high GCC levels received TAK-264 1.8 mg/kg as a 30-min intravenous infusion once every 21 days, for up to 1 year. The primary endpoint was objective response rate. Radiographic assessments of tumor burden were performed every 2 cycles (6 weeks). Results A total of 38 patients participated in the study. Patients received a median of 2 (range 1-14) cycles; 8 (21%) received at least 6 cycles. The most common adverse events were nausea (53%), fatigue (32%), and decreased appetite (29%). Grade ≥3 events including anemia, diarrhea, and neutropenia were seen in 14 (37%) patients. Systemic exposure to TAK-264 was maintained throughout each treatment cycle. Two patients (6%) with intermediate GCC expression had objective responses. Conclusions TAK-264 demonstrated a manageable safety profile in this patient population. The stage I interim analysis did not support continuation to stage II of the study.

Antibody-drug conjugate directed against the guanylyl cyclase antigen for the treatment of gastrointestinal malignancies

Antibody-directed cancer chemotherapy in the form of antibody-drug conjugates (ADCs) may improve the therapeutic index with the potential to enhance efficacy and decrease systemic toxicity. ADCs consist of three key components including an antibody that specifically binds to the target, a toxic agent and a linker which releases the toxic agent inside tumor cells. A novel ADC, MLN0264 (TAK-264) was recently investigated in patients with gastrointestinal (GI) malignancies. TAK-264 is an anti- guanylyl cyclase C (GCC) antibody conjugated via a protease-cleavable linker to the potent anti-microtubule agent monomethyl auristatin E (MMAE) (linker and toxin licensed from Seattle Genetics). Following binding to GCC, the ADC is internalized and transported to lysosomes where MMAE is released to bind to tubulin, leading to cell cycle arrest and apoptosis. This GCC targeting ADC has been evaluated in clinical studies in patients with advanced gastrointestinal malignancies. The early findings from Phase 1 study have shown preliminary activity signals in gastric, gastroesophageal, and pancreatic cancer. Results from two phase II studies in pancreatic and gastoesophageal adenocarcinoma showed only limited activity. Antibody-drug-conjugates offer a promising therapeutic modality aimed at providing target-directed cancer chemotherapy. Herein we discuss the GCC target and gastrointestinal malignancies where GCC based targeted therapies could further evolve and offer a significant clinical benefit.

Abstract CT117: A phase II trial of TAK-264, a novel antibody-drug conjugate (ADC), in patients with pancreatic adenocarcinoma expressing guanylyl cyclase C (GCC)

TAK-264 (formerly MLN0264) is a novel ADC consisting of a human monoclonal antibody that specifically targets GCC, the potent microtubule disrupting agent monomethyl auristatin E (MMAE), and a linker. GCC is selectively expressed in the gastrointestinal (GI) tract, and its expression is maintained through the spectrum of adenoma and carcinoma in the colorectum as well as the pancreas. A Phase 1 clinical trial has demonstrated a manageable safety profile and clinical activity of TAK-264 in patients with pancreatic and gastric carcinomas (NCT01577758). The primary objective of this Phase 2, open-label, non-randomized, multicenter study was to evaluate the overall response rate (ORR; complete response + partial response [PR]), safety, and tolerability of TAK-264 in previously treated adult patients with advanced or metastatic pancreatic adenocarcinoma expressing GCC. Here we report the findings from the interim analysis (IA). Per protocol, the IA was required to show objective responses in at least 2/12 patients with a defined GCC level to continue the second part of this study. Patients aged ?18 years with advanced or metastatic pancreatic adenocarcinoma expressing GCC (confirmed histologically by immunohistochemistry with an H score of ?10) who had received ?1 prior treatment, were eligible for inclusion. TAK-264 1.8 mg/kg was administered as a single 30 minute intravenous infusion on day 1 of a 21-day cycle for up to 1 year or until disease progression or unacceptable toxicity. At data cut-off (October 5, 2015), 43 patients had been enrolled. The median age was 61 years (range, 44-81). Participating patients had metastatic disease and received a median of 3 prior therapies (range, 1-8), with a median time since initial diagnosis of 16.6 months (range, 6-51). Of the 38 patients in the response-evaluable population, the ORR was 3% (PR, n = 1) and 9 patients (24%) had stable disease. A total of 28 (74%) patients experienced progressive disease. All patients received at least 1 dose of TAK-264 and were included in the safety population. The most common adverse events (AE) reported in ?15% of patients were abdominal pain (47%), nausea (37%), fatigue (35%), constipation and decreased appetite (each 28%), vomiting and neutropenia (each 26%), asthenia (21%), and dehydration (16%). Grade ?3 neutropenia, including febrile neutropenia, was reported in 7 (16%) and 2 (5%) patients, respectively. Grade ?3 GI AE included abdominal pain (9%), dyspepsia and vomiting (each 5%), and diarrhea (2%). Overall, a limited number of patients with GCC-positive pancreatic adenocarcinoma showed a modest clinical benefit from treatment with an ADC exploiting MMAE. The correlation between GCC levels and clinical outcomes is being explored. Based on the IA, these data do not support continuation of this study.

Citation Format: Khaldoun Almhanna, David Wright, Teresa Macarulla Mercadé, Jean-Luc Van Laethem, Antonio Cubillo Gracian, Carmen Guillén-Ponce, Jason Faris, Carolina Muriel Lopez, Richard Hubner, Johanna Bendell, Alain Bols, Jaime Feliú Batlle, Naureen Starling, Peter Enzinger, Devalingham Mahalingham, Wells Messersmith, Huyuan Yang, Adedigbo Fasanmade, Hadi Danaee, Thea Kalebic. A phase II trial of TAK-264, a novel antibody-drug conjugate (ADC), in patients with pancreatic adenocarcinoma expressing guanylyl cyclase C (GCC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT117.

Abstract CT107: Phase II trial of TAK-264 in previously treated patients (pts) with metastatic or recurrent adenocarcinoma of the stomach or gastroesophageal junction expression guanylyl cyclase C (GCC)

Gastric cancer is the third-leading cause of cancer-related deaths worldwide. Outcomes of current treatment regimens remain unsatisfactory, particularly in pts with advanced gastric cancer. TAK-264 is a novel drug conjugate consisting of a human monoclonal antibody that specifically targets GCC, which is expressed in approximately 70% of gastric cancers, linked to the potent microtubule disrupting agent monomethyl auristatin E. In the first-in-human Phase 1 study (NCT01577758) evaluating the safety of TAK-264, preliminary signals of clinical activity were reported in pts with gastric, gastroesophageal, and pancreatic carcinoma. The primary objective of this Phase 2 open-label, non-randomized, multicenter study (NCT02202759) was to evaluate the overall response rate (ORR; complete response + partial response) of adult pts with metastatic or recurrent adenocarcinoma of the stomach or gastroesophageal junction. Here we report the findings from the Interim Analysis (IA). Pts aged ?18 years with histologically-confirmed metastatic or advanced adenocarcinoma of the stomach or gastroesophageal junction, who were GCC-positive as demonstrated by immunohistochemistry with an H score ?10 and who had received ?1 prior therapy were eligible for inclusion. TAK-264 1.8 mg/kg was administered as a single 30-minute intravenous infusion on day 1 of a 21-day cycle until disease progression or unacceptable toxicity occurred. Pts were evaluated for a response every 2 cycles. At data cut-off (October 1, 2015), 37 pts had been enrolled (81% male), of which 36 (97%) pts were response-evaluable. The median age at baseline was 63 years (range, 31-81) and the median time from the initial diagnosis was 19.7 months (range, 5-76). Pts had received a median of 3 prior therapies (range, 1-7). Of the 36 pts in the response-evaluable population, the ORR was 6% (2 pts) and stable disease was observed in 15 (42%) pts. Progressive disease was experienced by 19 (53%) pts. All pts received at least one dose of TAK-264 and were included in the safety population. Common adverse events (AEs) observed in ?15% of pts included nausea (49%), fatigue (30%), decreased appetite and asthenia (each 27%), constipation and vomiting (each 22%), peripheral edema (19%), and diarrhea and anemia (each 16%). Diarrhea and neutropenia were the most prevalent Grade ?3 AEs, (each 5%). Other Grade ?3 gastrointestinal AEs included dysphagia, nausea and decreased appetite (each 1%). Results from the current IA suggest that few pts with GCC-positive metastatic or advanced adenocarcinoma of the stomach or gastroesophageal junction experienced limited clinical benefit with TAK-264 treatment. The correlation between GCC levels and clinical outcomes is being explored. Based on the IA, these data do not support continuation of the study.

Citation Format: Khaldoun Almhanna, Maria Luisa Limon Miron, David Wright, Antonio Cubillo Gracian, Richard Hubner, Jean-Luc Van Laethem, Carolina Muriel López, Maria Alsina, Federico Longo Muñoz, Johanna Bendell, Wells Messersmith, Huyuan Yang, Adedigbo Fasanmade, Hadi Danaee, Thea Kalebic. Phase II trial of TAK-264 in previously treated patients (pts) with metastatic or recurrent adenocarcinoma of the stomach or gastroesophageal junction expression guanylyl cyclase C (GCC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr CT107.

Phase 1 study of ixazomib, an investigational proteasome inhibitor, in advanced non-hematologic malignancies

PURPOSE

Ixazomib is an investigational proteasome inhibitor with demonstrated antitumor activity in xenograft models of multiple myeloma (MM), lymphoma, and solid tumors. This open-label, phase 1 study investigated intravenous (IV) ixazomib, in adult patients with advanced non-hematologic malignancies.

METHODS

Patients received IV ixazomib twice-weekly for up to twelve 21-day cycles. The 0.125 mg/m(2) starting dose was doubled (one patient/dose) until 1.0 mg/m(2) based on dose-limiting toxicities (DLTs) in cycle 1. This was followed by 3 + 3 dose-escalation and expansion at the maximum tolerated dose (MTD). Primary objectives included safety and MTD assessment. Secondary objectives included assessment of pharmacokinetics, pharmacodynamics, and disease response.

RESULTS

Ixazomib was escalated from 0.125 to 2.34 mg/m(2) to determine the MTD (n = 23); patients were then enrolled to MTD expansion (n = 73) and pharmacodynamic (n = 20) cohorts. Five patients experienced DLTs (1.0 and 1.76 mg/m(2): grade 3 pruritic rash; 2.34 mg/m(2): grade 3 and 4 thrombocytopenia, and grade 3 acute renal failure); thus, the MTD was 1.76 mg/m(2). Drug-related grade ≥3 adverse events (AEs) included thrombocytopenia (23 %), skin and subcutaneous (SC) tissue disorders (16 %), and fatigue (9 %). Among 92 evaluable patients, one (head and neck cancer) had a partial response and 30 had stable disease. Ixazomib terminal half-life was 3.8-7.2 days; plasma exposures increased dose-proportionally and drug was distributed to tumors. Inhibition of whole-blood 20S proteasome activity and upregulation of ATF-3 in tumor biopsies demonstrated target engagement.

CONCLUSIONS

In patients with solid tumors, ixazomib was associated with a manageable safety profile, limited antitumor activity, and evidence of downstream proteasome inhibition effects.

Abstract 4948: PET/CT clinical protocol design for the novel, first in class 68Ga labeled guanylyl cyclase C targeted peptide MLN6907 ([68Ga]MLN6907)

Acquisition and interpretation guidelines for clinical PET/CT imaging in oncology have been designed for whole-body 18F-FDG imaging and may not be optimized for assessment of other PET imaging tracers. Here we describe a methodology of PET/CT study design for the novel first in class 68Ga-labeled Guanylyl cyclase C (GCC) targeted peptide, [68Ga]MLN6907, based on a combination of in vitro, ex vivo, and in vivo preclinical imaging studies and model-based estimation of tumor parameters from simulated clinical PET data. GCC, a protein expressed in GI malignancies, is being targeted by the antibody drug conjugate MLN0264. GCC is also expressed on the healthy apical surface of the intestinal epithelium, which should be inaccessible to intravascular treatment. [68Ga]MLN6907 binds GCC with high affinity and is being developed as an imaging biomarker in an effort to help identify patients likely to respond to GCC-targeted therapy. In a series of experiments, the peptide affinity, internalization rate, and clearance were determined in patient-derived CRC xenografts with varied tumor microenvironmental phenotype. In addition to supporting the clinical development of the imaging agent, this data was used in combination with simulated clinical list-mode PET data to evaluate tumor parameter estimability under several clinically viable acquisition and reconstruction conditions. Specifically, liver CRC metastases of varying tumor diameter, antigen density, and vascularity were simulated in combination with PET imaging acquisition duration and reconstruction with and without partial-volume correction. Tumor, liver, and background time-activity curves (TACs) were generated from the reconstructed data and analyzed using a distributed tumor model to estimate the known tumor antigen density and vascularity. Analysis of the simulation studies revealed: 1) Partial volume correction is required for accurate antigen density and vascularity estimation; 2) Parameter estimation was most accurate within a tumor size range of 1-5 cm; 3) Parameter estimation was robust for all tested TAC reconstruction durations (e.g., 2, 3, 5, and 10 min); 4) Parameter estimation was optimal for common clinical acquisition times of 30-90 minutes; 5) Antigen density estimation was less accurate in poorly vascularized tumors. For the translation of a novel clinical biomarker, well controlled preclinical studies are critical; and, in this case, the findings combined with the distributed tumor model simulations directly guided the clinical image protocol. This rational and data-driven approach has the ability to not only improve the estimation of tumor properties in human subjects but also to guide the design of first-in-human oncology clinical imaging protocols with novel biomarkers.

Citation Format: Jacob Y. Hesterman, Kelly D. Orcutt, Ozlem Yardibi, Jerome T. Mettetal, Shu-Wen Teng, Donna Cvet, Jack Hoppin, Thea Kalebic, Daniel P. Bradley. PET/CT clinical protocol design for the novel, first in class 68Ga labeled guanylyl cyclase C targeted peptide MLN6907 ([68Ga]MLN6907). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4948. doi:10.1158/1538-7445.AM2014-4948

MLN0264, an investigational, first-in-class antibody-drug conjugate (ADC) targeting guanylyl cyclase C (GCC): Phase I, first-in-human study in patients (pts) with advanced gastrointestinal (GI) malignancies expressing GCC

TPS3646

Background: MLN0264, an investigational ADC that targets GCC, consists of a fully human monoclonal antibody conjugated to the cytotoxic microtubule disrupting agent monomethyl auristatin E (MMAE) via a protease-cleavable linker. MMAE and the linker technology are licensed from Seattle Genetics. GCC is a cell surface protein expressed by normal intestinal epithelial cells, ~95% of metastatic colorectal cancer (mCRC), and subsets of gastric and pancreatic cancers. In normal tissue, GCC is expressed on the apical side of epithelial cell tight junctions; therefore, systemically delivered GCC-targeting agents are expected to be preferentially delivered to tumor tissue in which cell polarity is disrupted. MLN0264 has demonstrated antitumor activity in mouse xenograft models of GCC-expressing tumors (Veiby et al. EORTC-NCI-AACR, 2012), supporting the scientific rationale for this first-in-human study. Methods: This study (NCT01577758) was designed to evaluate MLN0264 in ~60 adult pts with GI malignancies expressing GCC (≥1+), measurable disease by RECIST, and ECOG PS 0/1. This study is being conducted at 4 centers in the US and EU and is estimated to last ~36–42 months. Pts receive IV MLN0264 on day 1 of 21-day cycles for up to 17 cycles or until disease progression/unacceptable MLN0264-related toxicity. Dose escalation is proceeding via an adaptive Bayesian continual reassessment model approach based on dose-limiting toxicities in cycle 1. Following determination of the maximum tolerated dose (MTD), up to 14 pts each will be enrolled to mCRC and gastric carcinoma expansion groups to further characterize the safety, tolerability, and pharmacokinetics (PK) of MLN0264 and evaluate its clinical activity. The primary objectives are to evaluate the safety and tolerability, determine the MTD, and describe the PK of IV MLN0264. Secondary objectives are to evaluate the antitumor activity and immunogenicity of MLN0264. An exploratory objective is to examine the relationship between levels of GCC protein expression in tumor tissue and clinical response. Enrollment as of Jan 2013 was 12 pts. Clinical trial information: NCT01577758.

Tumor drug distribution and target engagement of MLN9708, an investigational proteasome inhibitor, in patients with advanced solid tumors

3077

Background: MLN9708 is a potent investigational proteasome inhibitor, which upon intravenous (IV) administration immediately hydrolyzes to the active form MLN2238. MLN9708 is currently being evaluated in a phase 1 trial in solid tumors (NCT00830869). This trial has a dose-escalation arm and five expansion cohorts: non-small cell lung cancer (NSCLC), soft tissue sarcoma, head and neck cancer, prostate cancer, and a tumor biopsy cohort of mixed histology. The purpose of the tumor biopsy cohort was to obtain pre- and post-dose biopsies to determine drug distribution and target engagement in post-dose tumor samples. The latter was measured by the increase in levels of ATF-3, a marker of unfolded protein response/endoplasmic reticulum stress, which is upregulated in response to proteasome inhibition. Methods: The tumor biopsy cohort included 20 patients dosed at the maximum tolerated dose who consented to core needle biopsies during screening and after either the first or second dose of MLN9708 (IV 1.76 mg/m2; 4–20 hours post-dose). Tumor biopsies were individually weighed, homogenized, and analyzed for the presence of MLN2238 using a quantified LC/MS/MS methodology. ATF-3 levels in tumors were determined by an immunohistochemical assay (IHC) on six sections for each tumor biopsy. Tumor area was identified using Aperio Genie, a machine learning program for pattern recognition, and the percentage of ATF-3 positive area in the tumor was measured. Results: Biopsies from 20 patients were collected for assessment of drug distribution and target engagement. Ten patients with paired pre- and post-dose biopsies of sufficient size were considered evaluable for PK analysis; MLN2238 was present in all 10 (100%) post-dose biopsies analyzed. Tumor pairs from 7 patients passed quality control by H&E staining for tumor content and were evaluable for ATF-3 IHC. Six of 7 paired samples (86%) showed a statistically significant (p<0.05) increase in post-dose ATF-3 levels. Conclusions: Overall, emerging data from MLN9708 phase 1 solid tumor analysis show that MLN2238 is present in tumors and demonstrates target engagement upon inhibition of the proteasome in tumor tissue biopsies.

MLN9708, an investigational proteasome inhibitor, in patients (pts) with solid tumors: Updated phase I results

e13603

Background: MLN9708 is a potent, reversible, orally bioavailable, and specific 20S proteasome inhibitor. This study (NCT00830869) assessed the safety, MTD, PK, PD, and antitumor activity of intravenous (IV) MLN9708 in pts with solid tumors. Methods: Pts aged ≥18 yrs (ECOG PS 0–2) received increasing doses of IV MLN9708 (starting at 0.125 mg/m2) on days 1, 4, 8, and 11 of 21-day cycles, for up to 12 cycles. MTD expansion cohorts included head and neck (H&N) cancer, non-small cell lung cancer, soft tissue sarcoma, prostate cancer, and a tumor PD expansion cohort. Plasma PK and blood PD data were analyzed by a non-compartmental method using WinNonlin software v5.3. The candidate PD biomarker ATF-3 was assessed using IHC. Results: 113 pts were enrolled; 23 in dose escalation and 96 in MTD expansion (includes 6 from dose escalation) cohorts. Median age of these heavily pretreated pts was 58 yrs (range 29–80). MTD was established as 1.76 mg/m2. Pts have received a median of 2 cycles (range 1–12) to date (data cut-off Dec 1, 2011); 22 received ≥4 cycles. 88% had ≥1 drug-related AE; most common drug-related AEs included fatigue (40%), thrombocytopenia (39%), rash (high level term) (33%), and nausea (32%). 52% of pts experienced grade ≥3 drug-related AEs, including thrombocytopenia (20%) and rash (9%). Drug-related peripheral neuropathy (PN) was seen in 13% of pts; 2 pts had grade 3 PN. 25% had drug-related SAEs, 15% discontinued due to AEs; 7 pts died, all unrelated to treatment. Of 75 response-evaluable pts, 26 achieved SD. A partial response (PR) was observed in a pt in the H&N cohort; response was achieved after 4 cycles and maintained through 8 cycles. Change in ATF-3 levels in tumor tissue post treatment was seen in 6 patients with tumor biopsy samples, indicating proteasome inhibition. PK data showed three-exponential plasma disposition, half-life of ~4–8 days, and dose linearity from 0.5–2.34 mg/m2. At MTD, maximal 20S proteasome inhibition in blood was approximately 60% at 0.08 hours. Whole blood PD effect was immediate and dose dependent. Conclusions: These data suggest that twice-weekly IV MLN9708 has a generally manageable safety profile and potential clinical utility; updated results will be presented.

Disruption of the MyoD/p21 Pathway in Rhabdomyosarcoma

Purpose. Rhabdomyosarcoma (RMS) is an embryonal tumor thought to arise from skeletal muscle cells that fail to differentiate terminally. The majority of RMSs express MyoD, a protein essential to the differentiation of skeletal muscle. It was recently shown that during myogenesis, MyoD activates the expression of the cyclin-dependent kinase inhibitor (CDKi), p21, which itself plays a critical role in normal muscle development. To investigate the integrity of the MyoD/p21 pathway in RMS, we analyzed p21 and its relationship to MyoD expression in RMS.

Methods. A panel of RMS samples was assembled from primary biopsies and from cell lines. Integrity of p21 was analyzed by single-strand conformation polymorphism (SSCP) and sequencing. Expression of p21 and MyoD was determined by Northern blot analysis, and the ability of exogenous p21 to arrest the cell cycle of RMS cell line was determined by transfection studies.

Results. Our analysis indicates that although p21 is wild type in RMS, there is an inverse correlation between the levels of p21 and MyoD in these tumors. Tumors that express significant amounts of MyoD fail to express p21. This does not appear to be the result of mutations within the potential CACGTG sites present in the p21 promoter region or in the coding region of p21. An additional group of RMSs express very high levels of p21 but express little, if any, MyoD. Furthermore, RD, a RMS cell line which expresses high levels of endogenous p21, undergoes withdrawal from the cell cycle following forced expression of p21, suggesting that the pathway which would lead to G₁ arrest from endogenous p21 activity is defective.

Discussion. These data suggest that the interaction between p21 and MyoD is defective in RMS although the precise nature of the defect remains to be elucidated.

c-MYC oncoprotein dictates transcriptional profiles of ATP-binding cassette transporter genes in chronic myelogenous leukemia CD34+ hematopoietic progenitor cells

Resistance to chemotherapeutic agents remains one of the major impediments to a successful treatment of chronic myeloid leukemia (CML). Misregulation of the activity of a specific group of ATP-binding cassette transporters (ABC) is responsible for reducing the intracellular concentration of drugs in leukemic cells. Moreover, a consistent body of evidence also suggests that ABC transporters play a role in cancer progression beyond the efflux of cytotoxic drugs. Despite a large number of studies that investigated the function of the ABC transporters, little is known about the transcriptional regulation of the ABC genes. Here, we present data showing that the oncoprotein c-MYC is a direct transcriptional regulator of a large set of ABC transporters in CML. Furthermore, molecular analysis carried out in CD34+ hematopoietic cell precursors of 21 CML patients reveals that the overexpression of ABC transporters driven by c-MYC is a peculiar characteristic of the CD34+ population in CML and was not found either in the population of mononuclear cells from which they had been purified nor in CD34+ cells isolated from healthy donors. Finally, we describe how the methylation state of CpG islands may regulate the access of c-MYC to ABCG2 gene promoter, a well-studied gene associated with multidrug resistance in CML, hence, affecting its expression. Taken together, our findings support a model in which c-MYC-driven transcriptional events, combined with epigenetic mechanisms, direct and regulate the expression of ABC genes with possible implications in tumor malignancy and drug efflux in CML.

Abstract 251: Disabled gene is involved in CML progression and its expression level at diagnosis can predict major molecular response (MMR) to imatinib therapy

Despite the role of Bcr-Abl in the pathogenesis of Chronic Myeloid Leukemia (CML) is well established, the mechanisms leading to CML progression remain unknown. Using our model of Drosophila melanogaster (Dm) transgenic for human Bcr-Abl we identified Dab1 and Dab2, the homologs of Dm Disabled (Dab), as genes involved in CML progression. In Dm the Dab loss of function induced a worsening of the hBcr-Abl eye phenotype and an even stronger phenotype was obtained using Dab RNAi fly strains. By contrast, Dab gain of function rescued Bcr-Abl phenotype. Dab is an adaptor protein acting downstream of many receptor tyrosine kinases (RTK). One of the human homolog of Dab, Dab1 is a large common fragile site gene involved in neural migration, and the other homolog Dab2 encodes an adaptor protein implicated in RTK signalling, endocytosis, cell adhesion and differentiation. The downregulation of both genes is described in many cancers suggesting their possible role in oncogenesis but their involvement in haematological malignancies has never been described. The aim of the study was to investigate the role of Dab1/2 in CML progression. Dab1 and Dab2 mRNA was analyzed by Real Time PCR in 94 samples from 82 CML patients (34 PB and 60 BM) distributed as follows: 55 patients at diagnosis (19 enrolled in TOPS study), 9 chronic phase (CP), 7 accelerated phase (AP) and 11 blast crisis (BC). 21 healthy donors (10 PB and 11 BM) were analyzed as control. In 18 patients, genes expression was analyzed during remission as well. Protein expression was evaluated by Western Blot (WB) and Immunofluorescence (IF). In addition, K562 cells were transfected with Dab plasmids to evaluate the effects on cell proliferation. We found that in CML patients Dab1/2 expression was significantly decreased both in BM and PB (p&lt;0.002 and p&lt;0.0004) compared to healthy donors. In BC Dab1/2 levels were further decreased whereas during remission the expression was comparable to normal values. Data analysis of patients included in TOPS studies shows that Dab1 values are higher among those achieving MMR by 12 months (median value: 0,017) compared to those without MMR (median value: 0,001); WB and IF confirmed the absence of Dab1/2 proteins in course of active CML samples while it reappeared during remission. Moreover, Dab1 transfection of K562 significantly reduced proliferation (p=0,002). In conclusion, our results show a significant decrease of Dab1/2 expression in BC samples, when compared to CP CML and healthy donors. Among CP CML patients the responders to Tyrosine Kinase Inhibitors (TKI) therapy have been detected to express higher Dab levels than non responders, and these expression levels can predict MMR to Imatinib therapy. In conclusion, this study points to specific gene pathways that might offer new molecular markers for the monitoring of CML and new targets for CML therapy in order to prevent or overcome disease progression.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 251.

Phase II study of neoadjuvant imatinib in glioblastoma: evaluation of clinical and molecular effects of the treatment

PURPOSE

Phase I-II studies indicate that imatinib is active in glioblastoma multiforme. To better understand the molecular and clinical effects of imatinib in glioblastoma multiforme, we conducted a neoadjuvant study of imatinib with pretreatment and posttreatment biopsies.

EXPERIMENTAL DESIGN

Patients underwent a computerized tomography-guided biopsy of their brain tumors. If diagnosed with glioblastoma multiforme, they were immediately treated with 7 days of imatinib 400 mg orally twice daily followed by either definitive surgery or re-biopsy. Pretreatment and posttreatment tissue specimens were tested by immunohistochemistry for Ki67 and microvessel destiny, and posttreatment specimens were analyzed for the presence of intact imatinib in tissue. Furthermore, pretreatment and posttreatment pairs were analyzed by Western blotting for activation of platelet-derived growth factor receptor, epidermal growth factor receptor (EGFR), phosphoinositide 3-kinase/AKT, and mitogen-activated protein kinase signaling pathways. Pharmacokinetic studies were also done.

RESULTS

Twenty patients were enrolled. Median survival was 6.2 months. Intact imatinib was detected in the posttreatment tissue specimens using mass spectrometry. There was no evidence of a drug effect on proliferation, as evidenced by a change in Ki67 expression. Biochemical evidence of response, as shown by decreased activation of AKT and mitogen-activated protein kinase or increased p27 level, was detected in 4 of 11 patients with evaluable, matched pre- and post-imatinib biopsies. Two patients showed high-level EGFR activation and homozygous EGFR mutations, whereas one patient had high-level platelet-derived growth factor receptor-B activation.

CONCLUSIONS

Intact imatinib was detected in glioblastoma multiforme tissue. However, the histologic and immunoblotting evaluations suggest that glioblastoma multiforme proliferation and survival mechanisms are not substantially reduced by imatinib therapy in most patients.

Inference of imatinib (IM) effects on leukemic stem cell (SC) compartment via mathematical modeling of IRIS treatment response data

7056

Background: Continuous treatment of chronic phase CML (CML-CP) patients with imatinib (IM) induces durable responses in majority of patients with a decreasing rate of relapse (Hochhaus et al, Blood. 2007;110). We present a mechanistic mathematical model which uses 6-year follow up data from the International Randomized Study of Interferon Versus STI571 (IRIS) trial (O'Brien et al, N Engl J Med. 2003;348:994) to explore IM effects on leukemic stem cells (SCs) across the patient population. Methods: The model approximates hemopoiesis as a 4-stage process in which only the first stage, corresponding to the SC compartment, is capable of self-renewal. Leukemic SCs, early and late progenitors were assumed to have higher self-renewal and expansion/differentiation rates than their normal counterparts. Model parameters describing the patient population distributions of leukemic/total SC ratio at diagnosis and sensitivity of leukemic cells to IM, were then fitted to individual cytogenetic and molecular response (CR/MR) data from 200 randomly selected newly-diagnosed CML-CP patients with 6-year follow-up. Results: Based on our analysis, successful characterization of the wide range of clinically observed treatment responses requires the inhibition of the leukemic SC compartment by IM. The median predicted inhibition of the leukemic SC proliferation rate was 79%. The model further predicted that after 6 years of IM treatment, 45% of patients would achieve a leukemic/total SC ratio below 0.1. Conclusions: We have developed a mathematical model of IM effects on CML-CP based on 6-year CR and MR data from the IRIS trial. In contrast to prior reports (Michor et al, Nature. 2005;435), our modeling predicts that IM reduces the leukemic SC compartment in most CML-CP patients, which could provide a mechanistic rationale for the decreasing rate of relapse observed in the study population.

[Table: see text]

Degradation of basement membrane components by vascular endothelial cells: role in neovascularization

A retina-derived substance (or substances) has been identified that stimulates vascular endothelial cells to degrade three structural components of basement membrane: type IV collagen, fibronectin and laminin. In basement membrane surrounding existing blood vessels, endothelial cells stimulated in this way can presumably migrate through the resulting gaps and form new vascular sprouts. These events may therefore represent the earliest steps in the formation of new blood vessels.

Biochemical evidence of tumor response and measurable levels of the drug in glioblastoma tissue from patients treated with imatinib

2023

Background: Glioblastoma multiforme (GBM) carries a grave prognosis. There are phase I-II studies indicating that imatinib is active in GBM in pre-treated patients. To better understand the molecular basis of imatinib’s activity in this disease we performed a pharmacodynamic neoadjuvant study with imatinib in GBM. Methods: Patients underwent CT guided biopsy of their brain tumors. If diagnosed with GBM they were immediately treated with 7 days of imatinib 400mg po BID followed by either definitive surgery or, if that was not feasible, followed by re-biopsy. Corticosteroid dose was stable during this period and valproic acid was the only anti-epileptic drug allowed in order to avoid pharmacokinetic interaction with imatinib. Treatment after recovery was as per usual institutional policy. Pre and post treatment tissue specimens were analyzed by immunohistochemistry, proteomic technology and molecular biological methods. Pharmacokinetic studies were also performed. Results: Twenty patients were enrolled in 2 institutions with a median age of 64, of which 14 were male and 6 female. PS was 0 in 2, 1 in 9 and 2 in 9. Seventeen patients had pure GBM, 2 had mixed GBM with astrocytoma and one had anaplastic astrocytoma. Eighteen patients had stable disease on pre and post treatment MRI, one had progressed and one was not evaluable. Median survival was 6.2 months (1.1–18mo). Intact imatinib was quantified in the post treatment tissue specimens and correlations were made with serum imatinib levels per patient. No correlation was seen. Tissue specimens were analyzed by in situ MALDI mass spectroscopy and differential protein expression profiles were detected, when pre and post treatment specimens were compared. The identification of candidate proteins is ongoing. In 11 patients with evaluable, high-quality, matched pre and post imatinib biopsies, 4 had biochemical evidence of tumor response (decreased AKT or MAPK, or increased p27). In addition, 2 patients showed high-level EGFR activation, and one patient had high-level PDGFR activation. Conclusions: Treatment of GBM patients with imatinib results in measurable levels of the drug in the tumor. Potential indicators of biochemical response in a subset of patients were identified.

No significant financial relationships to disclose.

Bone Sialoprotein Is Predictive of Bone Metastases in Resectable Non–Small-Cell Lung Cancer: A Retrospective Case-Control Study

Purpose

Bone metastases (BM) in non–small-cell lung cancer (NSCLC) may be detected at diagnosis or during the course of the disease, and are associated with a worse prognosis. Currently, there are no predictive or diagnostic markers to identify high-risk patients for metastatic bone dissemination.

Patients and Methods

Thirty patients with resected NSCLC who subsequently developed BM were matched for clinicopathologic parameters to 30 control patients with resected NSCLC without any metastases and 26 patients with resected NSCLC and non-BM lesions. Primary tumors were investigated by immunohistochemistry for 10 markers involved in bone resorption or development of metastases. Differences among groups were estimated by χ2 test, whereas the prognostic impact of clinicopathologic parameters and marker expression was evaluated by univariate (Wilcoxon and Mantel-Cox tests) and multivariate (Cox proportional hazards regression model) analyses.

Results

The presence of bone sialoprotein (BSP) was strongly associated with bone dissemination (P < .001) and, independently, with worse outcome (P = .02, Mantel-Cox test), as defined by overall survival. To evaluate BSP protein expression in nonselected NSCLC, a series of 120 consecutive resected lung carcinomas was added to the study, and BSP prevalence reached 40%. No other markers showed a statistically significant difference among the three groups or demonstrated a prognostic impact, in terms of both overall survival and time interval to metastases.

Conclusion

BSP protein expression in the primary resected NSCLC is strongly associated with BM progression and could be useful in identifying high-risk patients who could benefit from novel modalities of surveillance and preventive treatment.

Association of 12 serum biochemical markers of angiogenesis, tumour invasion and bone turnover with bone metastases from breast cancer: a crossectional and longitudinal evaluation

Complex biological pathways including angiogenesis, invasion, osteoclastic activation and bone matrix degradation are involved in the formation of bone metastasis (BM). The aim of our study was to investigate the cross-sectional and longitudinal associations of a panel of 12 serum biochemical markers reflecting biological pathways underlying BM development. In a cross-sectional study, we investigated 29 patients with primary breast carcinoma without BM (BC/BM-), 28 patients with breast carcinoma and BM (BC/BM+) and 15 healthy women. In longitudinal analyses, we investigated 34 patients for whom serum was obtained a two different time points: at the time of primary BC diagnosis and after a median time of 3 years. During this follow-up, 15 patients developed BM, whereas the other 19 remained free of BM. In patients who developed BM, the second samples were obtained before BM was documented by bone scan. The cross-sectional analyses have shown all biochemical markers to be significantly elevated in patients with BM, when compared to the patients without BM and healthy controls, except TGFbeta1 that was significantly decreased. Multivariable analyses showed that only the bone resorption markers TRACP 5b, CTX and ICTP, and the marker of angiogenesis VEGF were independently associated with BM. Those markers correctly distinguished 85% of BC patients with or without BM from normal individuals. Longitudinal analyses showed that patients with primary BC who developed BM during follow-up had higher levels of TRACP5b (+95%, P=0.08) at the time of primary diagnosis, those patients had also a higher increases of ICTP (P=0.006), MMP-7 (P=0.004) and TIMP-1 (P=0.017) during follow-up than patients who did not progress toward bone metastasis. This study provides evidence of increase and interrelationship of circulating markers of angiogenesis, invasion and bone resorption in patients with BC with and without BM. Markers of bone resorption have the highest independent diagnostic value for detecting and potentially predicting BM in breast carcinoma patients.

Bone sialoprotein is predictive of bone metastases in resectable non-small cell lung cancer: A case-control study and prevalence data

7049

Background: Bone metastases (BM) in non small cell lung cancer (NSCLC) may be present at diagnosis or develop in the follow up, are associated with a worse prognosis, and currently there are no chemical or biological markers predicting their clinical onset. Methods: Thirty cases of resected NSCLC which subsequently develop BM (group A - mean follow up time 27.2 months) were matched for several clinico-pathological parameters (including age, sex, stage of the disease, histology, differentiation grade, adjuvant therapy) to 30 cases of resected NSCLC without any metastases (group B - mean follow up time 75.1 months) and 26 resected NSCLC with non-bone metastatic (group C - mean follow up 21.1 months). Primary tumor samples were investigated by immunohistochemistry for 10 markers previously recognized to be involved in bone resorption or metastatization process (cathepsin K, bone sialoprotein [BSP], VEGF, MMP-2, p53, RECK, TIMP-1, CD-117, Ki-67 and TRAcP). For statistical analysis the intensity of the staining was assessed by a semi-quantitative score (0, <10%, 10–50%, >50% +ve tumor cells). Differences among groups were estimated by X-square test, whereas the prognostic impact of clinico-pathological parameters and markers expression was evaluated by univariate and multivariate analyses. Results: Among the different markers investigated, BSP was strongly associated to bone dissemination (p < 0.001) and, independently, to poor outcome (p = 0.02 by Mantel-Cox test). None of the other markers was differentially expressed within the groups or demonstrated a prognostic impact, both in terms of overall survival and of time interval to metastases. Based on these findings, the prevalence of BSP in NSCLC was further estimated in a large series of 120 resected lung carcinomas (M:F ratio 3:1; mean age 67 years; adenocarcinomas 55%, squamous cell carcinoma 39%, others 6%; stages: I 54%, II 17%, III 29%). BSP prevalence reached 40%, without any statistically significant difference according to histotype or other clinico-pathological parameters. Conclusions: BSP protein expression in resected NSCLC strongly predicts bone dissemination, and may therefore be useful in selecting patients for treatments targeted to inhibit bone metastatic spread.

[Table: see text]

Epigenetic transitions: towards therapeutic targets

Therapeutic approaches aimed at developing epigenetically-effective drugs are under intense investigation. Several classes of enzymes regulating histone acetylation and DNA methylation, which are required for epigenetic transitions, offer attractive targets for therapeutic interventions. Imbalances in histone acetylation and DNA methylation may play a significant role in the development of cancer and leukaemia and may provide a mechanistic rationale for targeting epigenetic modifications. Clinical trials designed to evaluate inhibitors of DNA methylation and histone deacetylase inhibitors are showing encouraging results in cancer patients. A growing quantity of data from preclinical research supports the notion that epigenetically-effective drugs could also find an application in other therapeutic areas. A number of emerging biomarkers may prove useful for monitoring drug effects and defining molecular signatures of response, toxicity and effective dose.

Chemoprevention of lung cancer: new directions

The refractoriness of advanced lung cancer to current treatment modalities requires new approaches to reduce the public health burden associated with this disease. One strategy that is currently being tested is chemoprevention, which aims to prevent the development of cancer in populations that are at high risk for cancer due to a variety of genetic or environmental factors. The key to the success of this approach, however, requires the identification of appropriately targeted efficacious, non-toxic agents as well as the methodologies to efficiently test them. Given the lack of success of previous phase III definitive lung cancer chemoprevention trials, there is a need for smaller scale phase II trials with molecular, imaging, or histologic endpoints to demonstrate preliminary safety and efficacy. The identification of molecular pathways critical to lung carcinogenesis offers the opportunity to develop targeted therapies for prevention. Means of optimizing the risk/benefit ratio associated with treatment include regional drug delivery that minimizes systemic toxicities and combination therapies. Identification of the most appropriate cohorts, such as former smokers without ongoing DNA damage due to carcinogen exposure, may uncover benefits that are hidden in a mixed population. Equally important is the identification of appropriate study endpoints that are predictive of patient outcomes such as cancer incidence. Further understanding of lung cancer biology will be critical to the success of future clinical trials.

Epigenetic changes: potential therapeutic targets

Recent advances in human genome research have resulted in novel approaches for the identification of epigenetic modifications associated with cancer. Modulators of DNA methylation and chromatin structure have a dramatic effect on gene expression, cellular proliferation, differentiation, and apoptosis. Molecular pathways regulating epigenetic events that occur during tumorigenesis have been exploited as new targets for therapeutic intervention. Clinical studies exploring the effectiveness of therapeutic agents targeting DNA methylation and acetylation of histones have yielded promising results. Molecular profiles of epigenetic alterations in cancer cells could allow better stratification of patients who may show responsiveness to specific treatments.

Novel anticancer function of inositol hexaphosphate: inhibition of human rhabdomyosarcoma in vitro and in vivo

Inositol hexaphosphate (IP6) is a naturally occurring polyphosphorylated carbohydrate that has been shown to suppress the growth of epithelial cancers, including those of breast and colon. The objective of this study was to investigate whether IP6 inhibits growth of rhabdomyosarcoma (RMS), a tumor of mesenchymal origin, which is the most common soft tissue sarcoma in children. We performed both in vitro and in vivo studies to evaluate the effect of IP6 on human RD cells growth. Our results show that IP6 suppresses growth of rhabdomyosarcoma cell line (RD) in vitro in a dose-dependent fashion. A 50% inhibition of cell growth (IC50) was induced by < 1.0 mM IP6. However, the removal of IP6 from the media, after 72 hours of treatment, allowed cells to recover their logarithmic growth. Exposure of RD cells to IP6 led to differentiation; cells became larger with abundant cytoplasm, expressing higher levels of muscle-specific actin. Consistent with in vitro observation, IP6 suppressed RD cell growth in vivo, in a xenografted nude mice model. When compared to controls, IP6-treated mice produced a 25 fold smaller tumors (p = 0.008), as observed after a two weeks treatment. In a second experiment, wherein the treatment period was extended to five weeks, a 49 fold (p = 0.001) reduction in tumor size was observed in mice treated with IP6. Histologically no evidence of tumor cell necrosis was observed. These data suggest a potential usefulness of this cytostatic, and non-cytotoxic, compound in novel therapeutic strategies for these types of tumor.

Expression of a kinase-deficient IGF-I-R suppresses tumorigenicity of rhabdomyosarcoma cells constitutively expressing a wild type IGF-I-R

Previous results have shown that the insulin-like growth factor type I receptor (IGF-I-R) plays a critical role in the control of rhabdomyosarcoma (RMS) growth. The purpose of this study was to investigate whether a mutated IGF-I-R, when expressed in RMS cells, may interfere with the function of the endogenous wild-type IGF-I-R. We also examined whether the expression of a mutated IGF-I-R may induce phenotypic changes in RMS cells. We used here the mutated IGF-I-R with a lysine to arginine residue 1003 substitution, called IGF-I-KR, which carries a mutation in the ATP-binding domain of the intracellular beta subunit, while the extracellular, ligand binding alpha subunit remains unchanged. We observed that the expression of this mutated IGF-I-KR markedly decreased the response of RMS cells to stimulation with IGF-I. While stimulation with IGF-I increases the autophosphorylation of IGF-I-R in the parent cells, stimulation with IGF-I failed to produce a comparable increase in autophosphorylation in the cells expressing the mutated IGF-I-KR. We also observed a decreased plating efficiency of cells expressing the mutated IGF-I-KR. Consistently, a decrease of RMS growth in vivo was observed in an animal model. Our data suggest that the IGF/IGF-I-R signaling pathway may be inhibited by expressing a mutated IGF-I-KR and that such a mutant gene could be utilized in developing novel therapeutic strategies to suppress RMS growth. 1998.

The insulin-like growth factor-I receptor is required for EWS/FLI-1 transformation of fibroblasts

Ewing's family of tumors is characterized by a well described reciprocal translocation, t(11;22)(q24;q12), which produces a fusion protein (EWS/FLI-1) that transforms mouse fibroblasts. The EWS/FLI-1 fusion protein has been shown to act as a potent chimeric transcription factor. Overexpression of insulin-like growth factor-I receptor (IGF-IR) has been implicated in many tumor models as playing a role in cell growth and tumorigenesis. In addition, blockade of the IGF-IR inhibits the growth of Ewing's family of tumors cells. Therefore, we first studied whether the presence of the IGF-IR is required for transformation by the EWS/FLI-1 fusion protein. To perform this study, we used two previously described fibroblast cell lines, R- and W, derived from an IGF-IR knockout mouse and a wild-type littermate, respectively. Neither W nor R- cells without the fusion protein formed soft agar colonies. However, W clones expressing the fusion message (WF cells) formed soft agar colonies, whereas R- clones expressing the fusion message (R-F cells) did not form soft agar colonies. Because the IGF-IR is required for EWS/FLI-1 transformation, we chose to investigate whether altered signaling occurs from the IGF-IR when the EWS/FLI-1 fusion is present. WF cells demonstrated a greater degree of ligand-stimulated insulin receptor substrate-1 phosphorylation when compared with W cells, suggesting that expression of the EWS/FLI-1 fusion protein alters the IGF-IR signaling pathway.

Role of the IGF-I receptor in mutagenesis and tumor promotion

Introduction

The insulin-like growth factor-I (IGF-I) receptor is a transmembrane protein tyrosine kinase which mediates the biological effects of IGF-I (LeRoith et al. 1995, Nissley & Lopaczynski 1991) and most of the actions of insulinlike growth factor-II (IGF-II). Binding of IGF-I to the IGF-I receptor results in receptor autophosphorylation, phosphorylation of intracellular substrates and activation of specific signaling processes involved in growth regulation and differentiation (Lowe 1991).

The role of the IGF-I receptor in normal mammalian development is exemplified by the work of Efstratiadis and co–workers on mice that carried a null mutation for the IGF-I receptor gene (Baker et al. 1993, Liu et al. 1993c). The growth in utero of these mice is severely inhibited and the mice die immediately after birth. Fibroblasts derived from these mice cannot grow in IGF-I-supplemented serum-free medium whereas mouse fibroblasts with functional IGF–I receptors are capable of growth (Sell et al. 1994), suggesting

Suppression of rhabdomyosarcoma growth by fumagillin analog TNP-470

The purpose of our study was to investigate a novel therapeutic approach for rhabdomyosarcoma (RMS) in an animal model. The pursuit of new therapeutic modalities for RMS is critically important since this type of tumor is the most common soft tissue sarcoma in children and because patients with metastatic disease may not be cured with current therapeutic modalities. We studied whether RMS growth may be suppressed by TNP-470, an analog of fumagillin, which was found to inhibit neoangiogenesis. Our data had shown that animals treated with TNP-470 (60 mg/kg), over a specific period of time, had approximately 50% smaller tumors than controls. Consistent with previous observations, treatment with TNP-470 decreases the level of the cyclin D1. Tumors dissected from TNP-470-treated animals had also considerable necrotic areas. In addition, TNP-470 had a direct cytotoxic effect on RMS cells in vitro. Our study has shown, therefore, that RMS in an animal model and in vitro responds to treatment with TNP-470, which suggests that the inhibitors of angiogenesis may be useful in a novel therapeutic design for RMS.

Human fetal glial cells constitutively produce HIV-inducing cytokines

The capacity of two human fetal glial cell lines, SVG and POJ, to increase the expression of human immunodeficiency virus (HIV) was investigated. As a cellular model for HIV latency, a chronically infected promonocytic cell line U1 was used. This cell line constitutively expresses a low level of viral activity. To monitor the level of HIV expression in U1 cells, reverse transcriptase (RT) activity was measured in the supernatant and the level of total HIV proteins was determined in cellular lysates. It was observed that the conditioned media from SVG and POJ cells increased RT activity in U1 cells in a dose-dependent fashion. In addition, the conditioned media from fetal glial cells caused an increase in total HIV protein synthesis. The capacity of conditioned media from both fetal glial cell lines to induce the expression of HIV was reduced by 45% in the presence of antibodies against human tumor necrosis factor alpha (TNFalpha), suggesting that one of the HIV-activating factors released by these cells was TNFalpha. The presence of TNFalpha and two other HIV-activating cytokines, IL-6 and IL-1, was confirmed by ELISA. It was also observed that glutathione increased the HIV-inducing capacity of the fetal glial cell-derived conditioned media. The finding that fetal glial cells constitutively secrete soluble factors which increase the expression of HIV in vitro suggests that in vivo, during perinatally acquired infection, similar events may occur. Fetal glial cells may play an important role in the pathogenesis of HIV-related encephalopathy.

Tumorigenic and mitogenic capacities are reduced in transfected fibroblasts expressing mutant insulin-like growth factor (IGF)-I receptors. The role of tyrosine residues 1250, 1251, and 1316 in the carboxy-terminus of the IGF-I receptor

Regulation of ligand-mediated signal transduction through transmembrane tyrosine kinase growth factor receptors involves phosphorylation of tyrosine residues in the intracellular domain of the receptor. The insulin-like growth factor-I (IGF-I) receptor contains three tyrosine residues in the carboxy-terminal domain at positions 1250, 1251, and 1316. Of these, only the tyrosine at position 1316 is conserved in the homologous position of the insulin receptor. Mutational analysis was used to study the role of these tyrosines in specific outcomes of IGF-I-mediated signal transduction. Mutations in the human IGF-I receptor were either replacement of tyrosines 1250 and 1251 with phenylalanine and histidine (yyFH), respectively, or replacement of the conserved distal tyrosine (position 1316) with phenylalanine (yCF). The yyFH mutation results in an IGF-I receptor with the amino acids found in the homologous position of the human insulin receptor. Cells overexpressing mutated IGF-I receptors were compared with cells expressing only endogenous IGF-I receptors or overexpressing wild-type IGF-I receptors. The ability of yyFH mutant IGF-I receptors to autophosphorylate the beta-subunit or phosphorylate insulin receptor substrate-1 was not significantly different from wild-type type IGF-I receptors. However, one or both of the proximal tyrosine residues (positions 1250 and 1251) in the carboxy-terminus of the IGF-I receptor are essential for IGF-I-stimulation of mitogenic and tumorigenic pathways. IGF-I-induced mitogenesis, measured as thymidine incorporation and cellular proliferation, was abrogated in cells overexpressing mutant IGF-I receptors with replacement of the proximal double tyrosines (positions 1250 and 1251). Fibroblasts expressing this mutant IGF-I receptor formed fewer tumors than the negative control cells, whereas cells expressing wild-type IGF-I receptors formed large tumors in all recipient mice injected. Conversely, cells expressing mutant IGF-I receptors with only the conserved distal tyrosine (position 1316) replaced had slightly reduced IGF-I-stimulated beta-subunit autophosphorylation, thymidine incorporation, and cellular proliferation when compared with cells expressing wild-type receptors. Phosphorylation of insulin receptor substrate-1 by the yCF mutant receptors was not impaired. Despite the ability of these mutant receptors to stimulate mitogenic growth, fibroblasts expressing this mutant receptor were also incapable of forming tumors in recipient nude mice. The distal tyrosine (position 1316) of the IGF-I receptor is crucial for tumor formation but is not essential for IGF-I stimulated mitogenesis. Thus, the tyrosine moieties in the carboxy-terminus of the IGF-I receptor participate in the signal transduction pathways that affect the mitogenic and tumorigenic potentials of cells expressing mutant IGF-I receptors.

Metastatic human rhabdomyosarcoma: molecular, cellular and cytogenetic analysis of a novel cellular model

A new human metastatic rhabdomyosarcoma (RMS) model was established and analyzed for a number of biologic, cytogenetic and molecular parameters. Consistent with previous studies, the metastatic capacity of different RMS cell variants did not correlate with their tumorigenic or proliferative capacities. Interestingly, a highly metastatic variant was diploid, while a nonmetastatic variant was tetraploid, which parallels previous clinical observations. Genes whose expression had been found to be associated with either low- or high-metastatic capacity in carcinoma or melanoma did not show a similar association with different metastatic variants of RMS, derived from a mesenchymal tumor. We also found, in transient reporter gene assays, that several promoters had higher transcriptional activity in highly metastatic than in nonmetastatic RMS cell variants. This novel human RMS metastatic model may be instrumental for a better understanding of the regulatory pathways that control the metastatic phenotype of tumors of mesenchymal origin.

1 alpha, 25-dihydroxy-16-ene-23-yne-26,27-hexafluorocholecalciferol (Ro24-5531) modulation of insulin-like growth factor-binding protein-3 and induction of differentiation and growth arrest in a human osteosarcoma cell line

1 alpha,25-Dihydroxycholecalciferol [1,25-(OH)2D3] is a potent differentiating agent in a variety of tumor cell lines. However, the induction of severe hypercalcemia has limited its clinical use. Several analogs have been synthesized that retain the antiproliferative differentiating effects of 1,25-(OH)2D3, but do not have the calcitropic effect of the parent compound. One such analog, 1 alpha,25(OH)2-16-ene-23-yne-26,27-hexafluorocholecalciferol (Ro24-5531), can induce differentiation in HL-60 cells and does not induce hypercalcemia in animal models. We, therefore, evaluated the effect of Ro24-5531 on a human osteosarcoma cell line, MG-63. Compared with 1,25-(OH)2D3, the analog Ro24-5531 is 10-100 times more potent as an inhibitor of MG-63 cell proliferation, as determined by [3H]thymidine incorporation and/or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The inhibition in cell growth is accompanied by a decrease in the expression of p34cdc2 (> 4-fold), a protein critically involved in cell cycle regulation. Ro24-5531 treatment of MG-63, at a concentration of 10(-8) mol/L, induced expression of the bone differentiation markers biglycan and osteocalcin, as determined by Northern analysis. These data suggest that Ro24-5531 treatment induces growth arrest coupled with differentiation. To begin to evaluate the mechanisms by which Ro24-5531 may exert an effect, we evaluated the effect of Ro24-5531 on components of the insulin-like growth factor I (IGF-I) signaling pathway, an important regulator of normal bone growth and differentiation. The expression of IGF-binding protein (IGFBP), IGFBP-3 messenger ribonucleic acid, and protein levels are increased 20-fold after 72 h of treatment with Ro24-5531 and are associated with a marked increase in detectable binding of ligand to binding protein, as measured by RRA. These data suggest an association between Ro24-5531-induced growth arrest and increased expression of IGFBP-3.

The role of the tyrosine kinase domain of the insulin-like growth factor-I receptor in intracellular signaling, cellular proliferation, and tumorigenesis

Insulin and insulin-like growth factor (IGF-I) receptors are heterotetrameric proteins consisting of two alpha-and two beta-subunits and members of the transmembrane tyrosine kinase receptors. Specific ligand binding to the receptor triggers a cascade of intracellular events, which begins with autophosphorylation of several tyrosine residues of the beta-subunit of the receptor. The triple cluster in the tyrosine kinase domain of the beta-subunit is the earliest and major autophosphorylation site. Previous studies have shown that substitutions of these three tyrosines by phenylalanines of both insulin and IGF-I receptors practically abolish any activation of cellular signaling pathways. We have studied the effect of double tyrosine mutations on IGF-I induced receptor autophosphorylation, activation of Shc and IRS-1 pathways, and cell proliferation and tumorigenicity. Substitution of tyrosines 1131/1135 blocks any detectable autophosphorylation, whereas substitution of tyrosines 1131/1136 or 1135/1136 only reduces autophosphorylation levels in some clones by approximately 50%. Nevertheless, all the cells expressing IGF-I receptors with double tyrosine substitutions demonstrated markedly reduced signaling through Shc and IRS-1 pathways. In addition, they were unable to respond to IGF-I-stimulated cell growth in culture, and tumor formation in nude mice was abrogated. These data suggest that the presence of tyrosine 1131 or 1135 essential for receptor autophosphorylation, whereas the presence of each of these tyrosines is necessary for a fully functional receptor.

HIV-1 modulates the expression of gelatinase A and B in monocytic cells

The levels of mRNA of both gelatinases A and B were dramatically decreased in HIV-infected cells, when compared to uninfected cells. The expression of gelatinase A in HIV-infected cells was selectively increased by tumor necrosis factor (TNF alpha) while the expression of gelatinase B was not affected. In contrast, in uninfected cells TNF alpha down regulated gelatinase B mRNA level, without affecting the gelatinase A. N-acethylcysteine (NAC) increased the levels of mRNA of both gelatinases. The conditioned media from HIV-infected and uninfected cells had comparable level of secreted gelatinase A protein. These data suggest that in monocytic cells different regulatory pathways control gelatinases A and B and that HIV could modulate in vivo the expression of these proteolytic enzymes, critically involved in regulation of invasion of basement membrane.