Magnetic resonance imaging determination of tumor grade and early response to temozolomide in a genetically engineered mouse model of glioma.

PURPOSE: The median survival for patients diagnosed with glioblastoma multiforme, the most common type of brain tumor, is less than 1 year. Animal glioma models that are more predictive of therapeutic response in human patients than traditional models and that are genetically and histologically accurate are an unmet need. The nestin tv-a (Ntv-a) genetically engineered mouse spontaneously develops glioma when infected with ALV-A expressing platelet-derived growth factor, resulting in autocrine platelet-derived growth factor signaling. EXPERIMENTAL DESIGN: In the Ntv-a genetically engineered mouse model, T2-weighted and T1-weighted, contrast-enhanced magnetic resonance images were correlated with histology, glioma grade (high or low), and survival. Magnetic resonance imaging (MRI) was therefore used to enroll mice with high-grade gliomas into a second study that tested efficacy of the current standard of care for glioma, temozolomide (100 mg/kg qdx5 i.p., n=13). RESULTS: The Ntv-a model generated a heterogeneous group of gliomas, some with high-grade growth rate and histologic characteristics and others with characteristics of lower-grade gliomas. We showed that MRI could be used to predict tumor grade and survival. Temozolomide treatment of high-grade tv-a gliomas provided a 14-day growth delay compared with vehicle controls. Diffusion MRI measurement of the apparent diffusion coefficient showed an early decrease in cellularity with temozolomide, similar to that observed in humans. CONCLUSIONS: The use of MRI in the Ntv-a model allows determination of glioma grade and survival prediction, distribution of mice with specific tumor types into preclinical trials, and efficacy determination both by tumor growth and early apparent diffusion coefficient response.

Vascular targeted nanoparticles for imaging and treatment of brain tumors.

PURPOSE: Development of new therapeutic drug delivery systems is an area of significant research interest. The ability to directly target a therapeutic agent to a tumor site would minimize systemic drug exposure, thus providing the potential for increasing the therapeutic index. EXPERIMENTAL DESIGN: Photodynamic therapy (PDT) involves the uptake of a sensitizer by the cancer cells followed by photoirradiation to activate the sensitizer. PDT using Photofrin has certain disadvantages that include prolonged cutaneous photosensitization. Delivery of nanoparticles encapsulated with photodynamic agent specifically to a tumor site could potentially overcome the drawbacks of systemic therapy. In this study, we have developed a multifunctional polymeric nanoparticle consisting of a surface-localized tumor vasculature targeting F3 peptide and encapsulated PDT and imaging agents. RESULTS: The nanoparticles specifically bound to the surface of MDA-435 cells in vitro and were internalized conferring photosensitivity to the cells. Significant magnetic resonance imaging contrast enhancement was achieved in i.c. rat 9L gliomas following i.v. nanoparticle administration. Serial magnetic resonance imaging was used for determination of pharmacokinetics and distribution of nanoparticles within the tumor. Treatment of glioma-bearing rats with targeted nanoparticles followed by PDT showed a significant improvement in survival rate when compared with animals who received PDT after administration of nontargeted nanoparticles or systemic Photofrin. CONCLUSIONS: This study reveals the versatility and efficacy of the multifunctional nanoparticle for the targeted detection and treatment of cancer.

A phase 1 study of the BCL2-targeted deoxyribonucleic acid inhibitor (DNAi) PNT2258 in patients with advanced solid tumors.

PURPOSE: Maximum tolerated dose, safety, pharmacokinetics, and pharmacodynamics were assessed in this phase 1 study of PNT2258, a BCL-2-targeted liposomal formulation of a 24-base DNA oligonucleotide called PNT100. METHODS: Patients with malignant solid tumors were assigned sequentially to one of ten dose-escalation cohorts of PNT2258 at 1, 2, 4, 8, 16, 32, 64, 85, 113, and 150 mg/m(2) administered intravenously on days 1 through 5 of each 21-day cycle. Pharmacokinetics were determined on days 1 and 5 of the first cycle. Lymphocyte and platelets concentrations were measured for evidence of BCL2-targeted effect. CT scans were used to identify radiologic evidence of anti-tumor effect. RESULTS: Twenty-two subjects received PNT2258, and the maximum tolerated dose for PNT2258 was not reached. Doses at or above 32 mg/m(2) resulted in exposure to PNT2258 above the exposure level required for anti-tumor activity in preclinical xenograft testing of 22,377 ng h/ml (PK analysis 2012). Fatigue was the most commonly reported adverse event. Dose-limiting toxicity, manifesting as a transient increase in aspartate aminotransferase, occurred at 150 mg/m(2), the highest dose tested. Four subjects, two each with diagnosis of non-small-cell lung cancer and sarcoma, treated at doses of 64 mg/m(2) or higher, remained on study for 5-8 cycles. CONCLUSIONS: PNT2258 was safe and well tolerated at the doses tested up to 150 mg/m(2). Exposure to PNT2258 resulted in clinically manageable decreases in lymphocyte and platelet concentrations.

Development and antitumor activity of a BCL-2 targeted single-stranded DNA oligonucleotide.

PNT100 is a 24-base, chemically unmodified DNA oligonucleotide sequence that is complementary to a region upstream of the BCL-2 gene. Exposure of tumor cells to PNT100 results in suppression of proliferation and cell death by a process called DNA interference. PNT2258 is PNT100 that is encapsulated in protective amphoteric liposomes developed to efficiently encapsulate the PNT100 oligonucleotide, provide enhanced serum stability, optimized pharmacokinetic properties and antitumor activity of the nanoparticle both in vivo and in vitro. PNT2258 demonstrates broad antitumor activity against BCL-2-driven WSU-DLCL2 lymphoma, highly resistant A375 melanoma, PC-3 prostate, and Daudi-Burkitt's lymphoma xenografts. The sequence specificity of PNT100 was demonstrated against three control sequences (scrambled, mismatched, and reverse complement) all encapsulated in a lipid formulation with identical particle characteristics, and control sequences did not demonstrate antiproliferative activity in vivo or in vitro. PNT2258 is currently undergoing clinical testing to evaluate safety and antitumor activity in patients with recurrent or refractory non-Hodgkin's lymphoma and additional studies are planned.