Mice with a targeted deletion of ␤3 integrin were used to examine the process by which tumor cells metastasize and destroy bone. Injection of B16 melanoma cells into the left cardiac ventricle resulted in osteolytic bone metastasis in 74% of ␤3 ؉/؉ mice by 14 days. In contrast, only 4% of ␤3 ؊/؊ mice developed bone lesions. Direct intratibial inoculation of tumor resulted in marrow replacement by tumor in ␤3 ؊/؊ mice, but no associated trabecular bone resorption as seen in ␤3 ؉/؉ mice. Bone marrow transplantation studies showed that susceptibility to bone metastasis was conferred by a bone marrowderived cell. To dissect the roles of osteoclast and platelet ␤3 integrins in this model of bone metastasis, osteoclast-defective src ؊/؊ mice were used. Src-null mice were protected from tumor-associated bone destruction but were not protected from tumor cell metastasis to bone. In contrast, a highly specific platelet aggregation inhibitor of activated ␣IIb␤3 prevented B16 metastases. These data demonstrate a critical role for platelet ␣IIb␤3 in tumor entry into bone and suggest a mechanism by which antiplatelet therapy may be beneficial in preventing the metastasis of solid tumors. Bone metastases arise by means of a multistep process whereby tumor cells migrate from a primary tumor, disseminate through the arterial system to the bone marrow, and stimulate osteoclast (OC) activation and tumor-associated destruction of cortical and trabecular bone (1-3). Once tumor cells enter the bone marrow cavity, tumor-associated bone destruction (osteolysis) occurs in part through induction of host OC activation. Bisphosphonate OC inhibitors can partially decrease pain, fracture, and cord compression associated with bone metastases; however, Ϸ50% of bisphosphonate-treated patients can still develop new bone metastases and resultant skeletal complications (4-7). The role of the OC and OC inhibitors in preventing tumor entry into and attachment to bone is unclear.Venous injection models of ''metastasis'' have demonstrated that in mice platelet adhesion can play a role in tumor cell lung infiltration (8-15). Gasic et al. (8) first demonstrated that lowering the platelet count in mice resulted in decreases in lung invasion after i.v. injection of tumor cell lines. Antibodies directed against platelet antigens involved in tumor adhesion to platelets also decrease lung tumors in mice (9-13) after i.v. tumor cell injection. These observations have been made exclusively in model systems that examine tumor cell growth after passive tumor cell filtration by the pulmonary capillary bed. Furthermore, the molecular mechanisms underlying these phenomena have not been elucidated. Metastasis to other organs and bone could not be evaluated in these venous tumor cell injection systems. We present a report exploring the role of platelets in arterial-mediated metastasis to bone or other visceral organs.Cell adhesion receptors play roles at multiple stages of metastasis (16)(17)(18)(19). We sought to examine the role of host cell ␤ 3 -containing integ...

ObjectiveThis phase I clinical study (NCT01415297) evaluated the safety, tolerability, maximum-tolerated dose (MTD), pharmacokinetics and pharmacodynamics of IT-139 (formerly NKP-1339) monotherapy in patients with advanced solid tumours. IT-139, sodium trans-(tetrachlorobis(1H-indazole)ruthenate(III)), is a novel small molecule that suppresses the stress induction of GRP78 in tumour cells. GRP78 is a key regulator of misfolded protein processing, and its upregulation in tumours is associated with intrinsic and drug-induced resistance.MethodsForty-six patients with advanced solid tumours refractory to treatment received intravenous infusions of IT-139 on days 1, 8 and 15 for every 28 days, and doses were evaluated across nine cohorts at 20, 40, 80, 160, 320, 420, 500, 625 and 780 mg/m2.ResultsOverall, IT-139 was well tolerated. The treatment-emergent adverse events (AEs) occurring in ≥20% of patients were nausea, fatigue, vomiting, anaemia and dehydration. The majority of patients had AEs that were ≤grade 2, regardless of relationship with the study drug. Of the total 38 efficacy-evaluable patients, one patient with a carcinoid tumour achieved a durable partial response. Nine additional patients achieved stable disease . The MTD was determined to be 625 mg/m2. IT-139 exhibited first-order linear pharmacokinetics.ConclusionsIT-139 demonstrated a manageable safety profile at the MTD and modest anti-tumour activity in this study of patients with solid tumours refractory to treatment. The lack of dose-limiting haematological toxicity and the absence of neurotoxicity position IT-139 well for use in combination with a broad spectrum of anticancer drugs.Trial registration numberNCT01415297.

Background Breast cancer mortality is principally due to tumor recurrence, which can occur following extended periods of clinical remission that may last decades. While clinical latency has been postulated to reflect the ability of residual tumor cells to persist in a dormant state, this hypothesis remains unproven since little is known about the biology of these cells. Consequently, defining the properties of residual tumor cells is an essential goal with important clinical implications for preventing recurrence and improving cancer outcomes. Methods To identify conserved features of residual tumor cells, we modeled minimal residual disease using inducible transgenic mouse models for HER2/neu and Wnt1-driven tumorigenesis that recapitulate cardinal features of human breast cancer progression, as well as human breast cancer cell xenografts subjected to targeted therapy. Fluorescence-activated cell sorting was used to isolate tumor cells from primary tumors, residual lesions following oncogene blockade, and recurrent tumors to analyze gene expression signatures and evaluate tumor-initiating cell properties. Results We demonstrate that residual tumor cells surviving oncogenic pathway inhibition at both local and distant sites exist in a state of cellular dormancy, despite adequate vascularization and the absence of adaptive immunity, and retain the ability to re-enter the cell cycle and give rise to recurrent tumors after extended latency periods. Compared to primary or recurrent tumor cells, dormant residual tumor cells possess unique features that are conserved across mouse models for human breast cancer driven by different oncogenes, and express a gene signature that is strongly associated with recurrence-free survival in breast cancer patients and similar to that of tumor cells in which dormancy is induced by the microenvironment. Although residual tumor cells in both the HER2/neu and Wnt1 models are enriched for phenotypic features associated with tumor-initiating cells, limiting dilution experiments revealed that residual tumor cells are not enriched for cells capable of giving rise to primary tumors, but are enriched for cells capable of giving rise to recurrent tumors, suggesting that tumor-initiating populations underlying primary tumorigenesis may be distinct from those that give rise to recurrence following therapy. Conclusions Residual cancer cells surviving targeted therapy reside in a well-vascularized, desmoplastic microenvironment at both local and distant sites. These cells exist in a state of cellular dormancy that bears little resemblance to primary or recurrent tumor cells, but shares similarities with cells in which dormancy is induced by microenvironmental cues. Our observations suggest that dormancy may be a conserved response to targeted therapy independent of the oncogenic pathway inhibited or properties of the primary tumor, that the mechanisms underlying dormancy at local and distant sites may be related, and that the dormant state represents a potential therapeutic target for preventing cancer recurrence.

BOLD-100, a ruthenium-based complex, sodium trans-[tetrachloridobis (1H-indazole) ruthenate (III)] (also known as IT-139, NKP1339 or KP1339), is a novel small molecule drug that demonstrated a manageable safety profile at the maximum tolerated dose and modest antitumor activity in a phase I clinical trial. BOLD-100 has been reported to inhibit the upregulation of the endoplasmic reticulum stress sensing protein GRP78. However, response to BOLD-100 varies in different cancer models and the precise mechanism of action in high-response versus low-response cancer cells remains unclear. In vitro studies have indicated that BOLD-100 induces cytostatic rather than cytotoxic effects as a monotherapy. To understand BOLD-100-mediated signaling mechanism in breast cancer cells, we used estrogen receptor positive (ER+) MCF7 breast cancer cells to obtain gene-metabolite integrated models. At 100 μM, BOLD-100 significantly reduced cell proliferation and expression of genes involved in the DNA repair pathway. BOLD-100 also induced reactive oxygen species (ROS) and phosphorylation of histone H2AX, gamma-H2AX (Ser139), suggesting disruption of proper DNA surveillance. In estrogen receptor negative (ER−) breast cancer cells, combination of BOLD-100 with a PARP inhibitor, olaparib, induced significant inhibition of cell growth and xenografts and increased gamma-H2AX. Thus, BOLD-100 is a novel DNA repair pathway targeting agent and can be used with other chemotherapies in ER− breast cancer.