DTI-015 produces cures in T9 gliosarcoma

Convection-Enhanced and Local Delivery of Targeted Cytotoxins in the Treatment of Malignant Gliomas

Despite advances in our knowledge about the genesis, molecular biology, and natural history of malignant gliomas and the use of a multi-disciplinary approach to their treatment, patients harboring this diagnosis continue to face a grim prognosis. At the time of diagnosis, patients typically undergo surgery for the establishment of a histologic diagnosis, the reduction of tumor burden, and the relief of mass effect, with the maintenance of the patient's neurological function in mind. This is followed by the administration of adjuvant therapeutics, including radiation therapy and chemotherapy.

Many investigational agents with laboratory evidence of efficacy against malignant gliomas have not met their promise in the clinical setting, largely due to the barriers that they must overcome to reach the tumor at a therapeutically meaningful concentration for a durable period of time. The relevant aspects of the blood-brain barrier, blood-tumor barrier, and blood-cerebrospinal fluid barrier, as they pertain to the delivery of agents to the tumor, will be discussed along with the strategies devised to circumvent them. This discussion will be followed by a description of agents currently in preclinical and clinical development, many of which are the result of intense ongoing research into the molecular biology of gliomas.

Intratumoral injection of cisplatin in various concentrations of ethanol for cisplatin-resistant lung tumors

Cisplatin [cis-diammineplatinum dichloride (DDP)] resistance is a major limitation in the treatment of lung cancer. We previously demonstrated that DDP dissolved in 5% ethanol (5% ethanol-DDP) injected intratumorally was able to eradicate DDP-resistant lung tumors and prolong survival, as 5% ethanol improved DDP delivery to the tumor. The present study aimed to investigate the efficacy of DDP in various concentrations of ethanol and determine the optimal ethanol concentration in which DDP exhibits optimal efficacy in reducing tumor volume and prolonging survival. The efficiency of DDP dissolved in 2, 5, 10, 20 and 50% ethanol (v/v) in DDP-resistant A549/DDP lung tumor-bearing Balb/C nude mice was investigated. Tumor growth and survival were evaluated in all the treatment groups. Microvessel density in xenograft tumor tissues was measured by immunohistochemistry. Our results revealed that 5% ethanol-DDP exhibited the highest efficiency in reducing tumor volume and prolonging survival among all the investigated ethanol-DDP combinations. We found that 5% ethanol-DDP produced the most significant inhibition of tumor angiogenesis among all the remaining ethanol-DDP combinations, while treatment with ethanol alone increased tumor angiogenesis. In conclusion, 5% ethanol-DDP produced the strongest tumor growth inhibition and longest survival among all the investigated ethanol-DDP combinations, possibly providing a novel therapeutic strategy for improving the survival of patients with DDP-resistant lung cancer. The potent inhibition of tumor angiogenesis by 5% ethanol-DDP may be one of the mechanisms underlying its superior efficiency.

Percutaneous Fine-Needle 5% Ethanol-Cisplatin Intratumoral Injection Combined with Second-Line Chemotherapy Improves On the Standard of Care in Patients with Platinum-Pretreated Stage IV Non-Small Cell Lung Cancer

BACKGROUND: Efficacy of second-line chemotherapy in platinum-pretreated non–small cell lung cancer (NSCLC) is poor. This study investigated efficacy of computed tomography–guided percutaneous fine-needle 5% ethanol-cisplatin intratumoral injection (CT-PFNECII) combined with second-line chemotherapy in patients with platinum-pretreated stage IV NSCLC. PATIENTS: Between October 2011 and July 2013, 34 eligible patients were randomly assigned to receive either CT-PFNECII combined with second-line chemotherapy (combination group, n = 17) or second-line chemotherapy alone (chemotherapy group, n = 17). The primary end points were the proportions of patients who achieved an overall response rate (ORR) and disease control rate (DCR). Secondary end points were median survival and progression-free survival (PFS). RESULTS: The ORR and DCR in the combination group were significantly higher than in the chemotherapy group (23.53% vs 11.76% for ORR, P < .01; and 58.82% vs 35.29% for DCR, P < .01). Compared with patients in the chemotherapy group, patients in the combination group had significantly longer PFS (5.4 months vs 3.0 months, P < .01) and median survival (9.5 months vs 5.3 months, P < .01). CONCLUSIONS: CT-PFNECII combined with second-line chemotherapy provided a higher response rate and improved survival than second-line chemotherapy for patients with platinum-pretreated stage IV NSCLC.

Phase II trial of intratumoral BCNU injection and radiotherapy on untreated adult malignant glioma

DTI-015 (BCNU dissolved in ethanol) utilizes solvent facilitated perfusion (SFP) for intratumoral drug delivery. A phase II clinical trial of DTI-015 and fractionated external beam radiotherapy on newly diagnosed, malignant gliomas investigated early changes in tumour physiology and metabolism, clinical outcome and safety. Pre- and post DTI-015 injection neuro-imaging included computed tomography (CT) cerebral blood flow and volume, glucose and thallium single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). Clinical status was determined before and after DTI-015, prior to radiotherapy and 3 monthly thereafter until progression (defined by Macdonald criteria). Primary endpoint was radiographic response. Secondary endpoints were progression free (PFS) and overall survival (OS). Twelve patients were enrolled; eight glioblastoma multiforme (GBM), four anaplastic astrocytoma (AA). Three days after DTI-015 injection, mean tumour blood flow (Paired t-test; P < 0.001) and blood volume (Paired t-test; P = 0.001) were significantly reduced. There was a significant decrease in glucose utilization (Paired t-test; P < 0.001) and thallium uptake (Paired t-test; P < 0.001) at 6 days. Tumour blood volume had a sustained reduction (Paired t-test; P = 0.001) at 26 days after DTI-015. There were two serious adverse events. Two patients with AA achieved a partial response. Median PFS was 39 weeks for AA and 27 weeks for GBM; median OS for GBM was 47 weeks and 132 weeks for AA. The imaging data forms a biological basis for understanding the effects of high dose BCNU delivered intratumorally by SFP, and suggests early effects on tumour vasculature and metabolism.

Rat brain tumor models in experimental neuro-oncology: the C6, 9L, T9, RG2, F98, BT4C, RT-2 and CNS-1 gliomas

In this review we will describe eight commonly used rat brain tumor models and their application for the development of novel therapeutic and diagnostic modalities. The C6, 9L and T9 gliomas were induced by repeated injections of methylnitrosourea (MNU) to adult rats. The C6 glioma has been used extensively for a variety of studies, but since it arose in an outbred Wistar rat, it is not syngeneic to any inbred strain, and its potential to evoke an alloimmune response is a serious limitation. The 9L gliosarcoma has been used widely and has provided important information relating to brain tumor biology and therapy. The T9 glioma, although not generally recognized, was and probably still is the same as the 9L. Both of these tumors arose in Fischer rats and can be immunogenic in syngeneic hosts, a fact that must be taken into consideration when used in therapy studies, especially if survival is the endpoint. The RG2 and F98 gliomas were both chemically induced by administering ethylnitrosourea (ENU) to pregnant rats, the progeny of which developed brain tumors that subsequently were propagated in vitro and cloned. They are either weakly or non-immunogenic and have an invasive pattern of growth and uniform lethality, which make them particularly attractive models to test new therapeutic modalities. The CNS-1 glioma was induced by administering MNU to a Lewis rat. It has an infiltrative pattern of growth and is weakly immunogenic, which should make it useful in experimental neuro-oncology. Finally, the BT4C glioma was induced by administering ENU to a BD IX rat, following which brain cells were propagated in vitro until a tumorigenic clone was isolated. This tumor has been used for a variety of studies to evaluate new therapeutic modalities. The Avian Sarcoma Virus (ASV) induced tumors, and a continuous cell line derived from one of them designated RT-2, have been useful for studies in which de novo tumor induction is an important requirement. These tumors also are immunogenic and this limits their usefulness for therapy studies. It is essential to recognize the limitations of each of the models that have been described, and depending upon the nature of the study to be conducted, it is important that the appropriate model be selected.

Diffusion Imaging: Insight to Cell Status and Cytoarchitecture

Diffusion MR imaging techniques are based on the molecular mobility of water, which is sensitive to interaction with intracellular elements, macromolecules, cell membranes, the density of cells, and microstructural organization. Disease processes that alter cell-water homeostasis, cell density, and cytoarchitecture affect water mobility and are quantifiable by diffusion MR imaging methodologies. Similarly, therapeutic intervention that alters these properties may be monitored for efficacy via diffusion MR imaging. This article outlines basic technical concepts and applications of diffusion imaging with an emphasis on oncology.

Levels and distribution of BCNU in GBM tumors following intratumoral injection of DTI-015 (BCNU-ethanol)

The alkylation products formed by in vitro treatment of DNA with tritium-labeled 1,3-bis(2-chloroethyl)-1-nitrosourea ((3)H-BCNU) were identified and quantified. Twelve adducts were resolved by high-performance liquid chromatography (HPLC). The principal DNA adducts formed by BCNU treatment corresponded to N-7-(2-hydroxyethyl)guanine (N7-HOEtG) (26%), N-7-(2-chloroethyl)guanine (15%), and phosphotriesters (19%). In addition, several minor products were identified as 1,2-(diguan-7-yl)ethane, N-1-(2-hydroxyethyl)-2-deoxyguanosine, 1-(N-1-2-deoxyguanosinyl), 2-(N-3-2-deoxycytidyl)ethane cross-link, and O-6-(2-hydroxyethyl)-2-deoxyguanosine, and individually they represented 1% to 5% of the total alkylation. An HPLC-electrochemical method was applied to quantify the levels of N7-HOEtG in samples treated with BCNU. Treatment of either purified DNA or U87MG cells with various amounts of BCNU produced a linear increase in the amount of N7-HOEtG. These results demonstrated that the levels of N7-HOEtG formed by BCNU treatment could be used as a molecular dosimeter of BCNU treatment dose. We measured the levels of N7-HOEtG in DNA isolated from tumor samples taken from four patients with GBM tumors following stereotactic intratumoral injection with DTI-015 (BCNU-ethanol). The level of N7-HOEtG in these samples ranged from 14.7 to 121.9 micromol N7-HOETG/mol DNA within 1 cm of the site of injection. As the distance from the site of injection increased, the levels of N7-HOEtG in tumor DNA decreased. In two of the samples, the levels of N7-HOEtG were 0.2 to 0.3 micromol N7-HOETG/mol DNA at 3.5 to 3.9 cm from the site of injection, demonstrating significant distribution of BCNU in the tumor. The levels of N7-HOEtG in these tumor samples corresponded to BCNU treatment concentrations of 0.02 to 43.0 mM. These studies demonstrate that stereotactic intratumoral injection of DTI-015 into human GBM tumors produces high concentrations of BCNU up to 2.5 cm from the site of injection in some of the tumors. These observations suggest that intratumoral injection of DTI-015 may be of benefit in the treatment of primary and recurrent GBM tumors.

Intratumoral injection of BCNU in ethanol (DTI-015) results in enhanced delivery to tumor – a pharmacokinetic study

Solvent facilitated perfusion (SFP) has been proposed as a technique to increase the delivery of chemotherapeutic agents to tumors. SFP entails direct injection of the agent into the tumor in a water-miscible organic solvent, and because the solvent moves easily through both aqueous solutions and cellular membranes it drives the penetration of the solubilized anticancer agent throughout the tumor. To test this hypothesis, we compared the pharmacokinetics (PK) of 14C-labeled 1,3-bis-chlorethyl-1-nitrosourea (BCNU) in intra-cerebral 9L rat gliomas after intravenous (IV) infusion in 90% saline--10% ethanol or direct intratumoral (IT) injection of 14C-BCNU in 100% ethanol (DTI-015). Treatment with DTI-015 yielded a peak radioactive count (Cmax) for the 14C label that was 100-1000 fold higher in the tumor than in all other tissues in addition to a concentration in the tumor that was 100-fold higher than that achieved following IV infusion of 14C-BCNU. Pathologic and auto-radiographic analysis of tissue sections following IT injection of 14C-BCNU in ethanol into either tumor or normal rat brain revealed both an enhanced local volume of distribution and an increased concentration of BCNU delivered to tumor compared to non-tumor bearing brain. To investigate the mechanism behind the SFP of BCNU to the tumor both dynamic contrast and perfusion MRI were performed on 9L tumors before and after treatment and demonstrated a decrease in tumor perfusion following IT injection of DTI-015. Finally, initial PK of patient blood samples following administration of DTI-015 into relapsed high-grade glioma indicated a 20-fold decrease in systemic exposure to BCNU compared to IV infusion of BCNU providing further evidence for the enhanced therapeutic ratio observed for DTI-015.

Therapeutic efficacy of DTI-015 using diffusion magnetic resonance imaging as an early surrogate marker

To investigate diffusion weighted magnetic resonance imaging as a quantitative surrogate marker for evaluating the therapy-induced cellular changes in an orthotopic experimental glioma model, tumors were treated with direct intratumoral administration of DTI-015, a solution of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) in 100% EtOH. Intracerebral 9L tumors were induced in Fischer 344 rats, and three treatment groups were established: DTI-015, EtOH, and sham. Two groups of rats received intratumoral injection of either 67 mg/mL BCNU in EtOH or EtOH alone at 50% of the tumor volume up to a maximum of 30 mul under stereotactic guidance. Diffusion magnetic resonance images were acquired before treatment and after treatment at 1, 24, 48, and 72 hours and then 3 times per week thereafter. Tumor cell viability was examined using multislice diffusion weighted magnetic resonance imaging with diffusion weighted transverse magnetic resonance images and histogram plots of each tumor quantified over time. Control animals (EtOH- or sham-treated animals) showed mean apparent diffusion coefficients (ADCs) that remained essentially unchanged over the experimental time course. In contrast, rats treated with DTI-015 showed a significant increase in ADC relative to the pretreatment within 24 hours, which further increased over time, followed by a significant therapeutic response as evidenced by subsequent tumor volume shrinkage, development of a cystic region, and enhanced animal survival. Finally, not only were ADC measurements predictive of differences between treatment groups, but they also yielded spatial and temporal data regarding the efficacy of treatment within individual treated animals that could be used to guide subsequent therapy.

Neurosurgical delivery of chemotherapeutics, targeted toxins, genetic and viral therapies in neuro-oncology

Local delivery of biologic agents, such as gene and viruses, has been tested preclinically with encouraging success, and in some instances clinical trials have also been performed. In addition, the positive pressure infusion of various therapeutic agents is undergoing human testing and approval has already been granted for routine clinical use of biodegradable implants that diffuse a chemotherapeutic agent into peritumoral regions. Safety in glioma patients has been shown, but anticancer efficacy needs additional refinements in the technologies employed. In this review, we will describe these modalities and provide a perspective on needed improvements that should render them more successful.

Stereotactic injection of DTI-015 into recurrent malignant gliomas: phase I/II trial

DTI-015 (BCNU in 100% ethanol) utilizes solvent facilitated perfusion for the intratumoral treatment of gliomas. The ethanol solvent vehicle facilitates a rapid and thorough saturation of the tumor with the dissolved anticancer agent BCNU. We conducted a phase I/II dose escalation study of DTI-015 in 40 heavily pretreated patients with inoperable recurrent malignant glioma. The study goals were to establish a maximally tolerated dose (MTD) for DTI-015 and assess its safety and activity. Patients received stereotactic intratumoral injection of DTI-015 under magnetic resonance imaging guidance. Dose escalation was performed in two phases. First, DTI-015 volume was escalated at a set BCNU concentration of 12.5 mg/ml; second, BCNU mg dose was escalated by increasing BCNU concentration to 30, 45, 60, and 75 mg/ml. A MTD of 5 ml and 240 mg was established. Twenty-five of 28 DTI-015 treatments (89%) using </=MTD were administered safely without producing high-grade drug-related adverse events. Median survival for GBM patients administered DTI-015 at </=MTD was 55 weeks. Magnetic resonance imaging demonstrated stable disease in 72% of evaluable patients with a median of 10.5 weeks. The results suggest that DTI-015 administered at </=MTD is well tolerated and active in patients with inoperable recurrent GBM.