Roberto Diaz

Targeted Nanoparticles That Deliver a Sustained, Specific Release of Paclitaxel to Irradiated Tumors

To capitalize on the response of tumor cells to XRT, we developed a controlled-release nanoparticle drug delivery system using a targeting peptide that recognizes a radiation-induced cell surface receptor. Phage display biopanning identified Gly-Ile-Arg-Leu-Arg-Gly (GIRLRG) as a peptide that selectively recognizes tumors responding to XRT. Membrane protein extracts of irradiated glioma cells identified glucose-regulated protein GRP78 as the receptor target for GIRLRG. Antibodies to GRP78 blocked the binding of GIRLRG in vitro and in vivo. Conjugation of GIRLRG to a sustained-release nanoparticle drug delivery system yielded increased paclitaxel concentration and apoptosis in irradiated breast carcinomas for up to 3 weeks. Compared with controls, a single administration of the GIRLRG-targeted nanoparticle drug delivery system to irradiated tumors delayed the in vivo tumor tripling time by 55 days (P = 0.0001) in MDA-MB-231 and 12 days in GL261 (P < 0.005). This targeting agent combines a novel recombinant peptide with a paclitaxel-encapsulating nanoparticle that specifically targets irradiated tumors, increasing apoptosis and tumor growth delay in a manner superior to known chemotherapy approaches.

Noninvasive assessment of cancer response to therapy

Rapid assessment of cancer response to a therapeutic regimen can determine efficacy early in the course of treatment. Although biopsies of cancer can be used to rapidly assess pharmacodynamic response, certain disease sites are less accessible to repeated biopsies. Here, we simultaneously assess response in all sites of disease within days of starting therapy by use of peptide ligands selected for their ability to discern responding from nonresponding cancers. When conjugated to near-infrared imaging agents, the HVGGSSV peptide differentiates between these two types of cancer. Rapid, noninvasive assessment of the pharmacodynamic response within cancer promises to accelerate drug development and minimize the duration of treatment with ineffective regimens in cancer patients.

Novel synthetic curcumin analogues EF31 and UBS109 are potent DNA hypomethylating agents in pancreatic cancer

DNA methylation is a rational therapeutic target in pancreatic cancer. The activity of novel curcumin analogues EF31 and UBS109 as demethylating agents were investigated. MiaPaCa-2 and PANC-1 cells were treated with vehicle, curcumin, EF31 or UBS109. EF31 and UBS109 resulted in significantly higher inhibition of proliferation and cytosine methylation than curcumin. Demethylation was associated with re-expression of silenced p16, SPARC, and E-cadherin. EF31 and UBS109 inhibited HSP-90 and NF-κB leading to downregulation of DNA methyltransferase-1 (DNMT-1) expression. Transfection experiments confirmed this mechanism of action. Similar results were observed in vitro when subcutaneous tumors (MiaPaCa-2) were treated with EF31 and UBS109.

Hypothyroidism as a Consequence of Intensity-Modulated Radiotherapy With Concurrent Taxane-Based Chemotherapy for Locally Advanced Head-and-Neck Cancer

PURPOSE To conduct a retrospective review of 168 consecutively treated locally advanced head-and-neck cancer (LAHNC) patients treated with intensity-modulated radiotherapy (IMRT)/chemotherapy, to determine the rate and risk factors for developing hypothyroidism. METHODS AND MATERIALS Intensity-modulated radiotherapy was delivered in 33 daily fractions to 69.3 Gy to gross disease and 56.1 Gy to clinically normal cervical nodes. Dose-volume histograms (DVHs) of IMRT plans were used to determine radiation dose to thyroid and were compared with DVHs using conventional three-dimensional radiotherapy (3D-RT) in 10 of these same patients randomly selected for replanning and with DVHs of 16 patients in whom the thyroid was intentionally avoided during IMRT. Weekly paclitaxel (30 mg/m(2)) and carboplatin area under the curve-1 were given concurrently with IMRT. RESULTS Sixty-one of 128 evaluable patients (47.7%) developed hypothyroidism after a median of 1.08 years after IMRT (range, 2.4 months to 3.9 years). Age and volume of irradiated thyroid were associated with hypothyroidism development after IMRT. Compared with 3D-RT, IMRT with no thyroid dose constraints resulted in significantly higher minimum, maximum, and median dose (p < 0.0001) and percentage thyroid volume receiving 10, 20, and 60 Gy (p < 0.05). Compared with 3D-RT, IMRT with thyroid dose constraints resulted in lower median dose and percentage thyroid volume receiving 30, 40, and 50 Gy (p < 0.005) but higher minimum and maximum dose (p < 0.005). CONCLUSIONS If not protected, IMRT for LAHNC can result in higher radiation to the thyroid than with conventional 3D-RT. Techniques to reduce dose and volume of radiation to thyroid tissue with IMRT are achievable and recommended.

Antiangiogenic effects of ganetespib in colorectal cancer mediated through inhibition of HIF-1α and STAT-3

Hypoxia-inducible factors (HIFs) and STAT-3 play essential roles in angiogenesis. HIF-1α and STAT-3 are clients of the heat shock protein 90 (HSP90). We hypothesized that ganetespib, a potent HSP90 inhibitor, would disrupt angiogenesis in colorectal cancer (CRC) through inhibition of HIF-1α and STAT-3. CRC cell lines (HCT116 and HT29) were used in all the experiments. Egg CAM and HUVEC assays revealed decreased angiogenesis in ganetespib treated cell lines. Ganetespib inhibited matrigel plug vascularization and tumor growth of xenografts. Significant inhibition of PDGFA, FGF2, Ang-1, Ang-2, TGFβ1, VEGF, HIF-1α and STAT-3 expression was observed in both cell lines treated ganetespib. HIF-1α overexpression resulted in the increase VEGF and STAT-3 expression and this was inhibited by ganetespib. HIF-1α knockdown inhibited VEGF and STAT-3 expression. STAT-3 knockdown inhibited VEGF but not HIF-1α expression. HSP90, STAT-3 and VEGF expression was significantly higher in CRC compared to adjacent normal tissue. Significant downregulation of PDGFA, FGF2, Ang-1, Ang-2, TGFβ1, VEGF, STAT-3 and HIF-1α mRNA was observed in the post ganetespib treatment tumor samples from patients with rectal cancer. These results collectively suggest that inhibition of HSP90 is a promising antiangiogenic strategy in CRC. HSP90 angiogenic effects are mediated through HIF-1α and STAT-3.

Cytoplasmic clusterin expression is associated with longer survival in patients with resected non small cell lung cancer.

Background: Clusterin is a glycoprotein that has been implicated in many processes, including apoptosis, cell cycle regulation, and DNA repair. Previous studies have examined the prognostic value of clusterin expression in various malignancies. In the present study, we examined clusterin staining in tumors resected from patients with non–small cell lung cancer (NSCLC). Materials and Methods: Tumor specimens were obtained for 113 patients with completely resected NSCLC from paraffin-embedded tissue microarrays and stained with an antibody specific for clusterin. Staining patterns were observed and graded based on intensity and then correlated with clinical data. Results: Positive cytoplasmic clusterin staining was observed in 44 patients, and weak/negative staining was observed in 62 patients. Patients who had tumors that stained positive for cytoplasmic clusterin had significantly longer survival in multivariate analysis (hazard ratio 0.487, 95% confidence interval 0.27-0.89). A correlation was also observed for recurrence-free survival, which approached statistical significance (hazard ratio 0.345, 95% confidence interval 0.12-1.02). In univariate analysis, patients with clusterin-positive tumors had a 63% 3-year survival, whereas patients with clusterin-negative tumors had a 42% 3-year survival (P = 0.0108); clusterin-positive tumors also had significantly less recurrence (P = 0.0231). Conclusions: Cytoplasmic clusterin staining is present in a substantial number of NSCLC tumors and may be a biomarker for longer survival in patients with surgically resected NSCLC. (Cancer Epidemiol Biomarkers Prev 2007;16(9):1845–51)

Linear release nanoparticle devices for advanced targeted cancer therapies with increased efficacy

The cross-linked supramolecular structure of prepared polyester based nanoparticles enable increased and efficient small molecule drug loading after nanoparticle formation and post-modification with targeting peptides via thiol-ene ‘click’ chemistry. It could be demonstrated that the drug loading does not influence the structural integrity of the particle and its diameter was not significantly changed. A prolonged linear release profile of the drug without the typical ‘burst effect’ was observed in emulsified particles and mirrored the linear degradation profile of the investigated particles, which are critical properties for controlled and predictable pharmacokinetics in cancer therapies. Furthermore, the final peptide-targeted and drug-loaded particles were found to be readily dispersed in buffer or water, and with the confirmed biocompatibility, these novel and adjustable drug delivery systems are promising vectors for the treatment of various cancers.

Dose to the inferior pharyngeal constrictor predicts prolonged gastrostomy tube dependence with concurrent intensity-modulated radiation therapy and chemotherapy for locally-advanced head and neck cancer.

BACKGROUND AND PURPOSE To determine if dose and/or dose-volume parameters to anatomic swallowing structures are predictive of gastrostomy tube (PEG) dependence from chemotherapy-intensity modulated radiotherapy (IMRT) in locally advanced head and neck cancer (LAHNC). METHODS AND MATERIALS A retrospective study was performed on 141 consecutive patients with LAHNC (squamous cell) treated with definitive chemoIMRT with weekly concurrent carboplatin and paclitaxel. Late dysphagia was assessed by length of PEG requirement. Analysis of IMRT dose was retrospectively performed for critical swallowing structures. RESULTS Approximately 62% of patients required PEG, the majority placed during treatment. Mean and median time for PEG was 7.7 and 4.4 months respectively (range 1.4-43.8). Only IMRT dose to the inferior constrictor was significantly associated with length of PEG. Mean dose (of individual mean doses) was 47 Gy for prolonged PEG use versus 41 Gy for PEG ⩽ 12 months. V40 to the inferior constrictor also correlated with PEG >12 months (p = 0.02) with a mean V40 of 48% versus 41% for PEG ⩽ 12 months. CONCLUSIONS IMRT dose to the inferior constrictor correlated with persistent dysphagia requiring prolonged PEG use. Maintaining mean inferior constrictor dose to ⩽ 41 Gy and V40 to ⩽ 41% may help minimize gastrostomy tube dependence.

Impact of FDG PET/CT on delineation of the gross tumor volume for radiation planning in non-small-cell lung cancer.

Purpose: Computed tomography (CT) remains the gold standard for delineation of tumor volumes for radiotherapy (RT) planning. However, positron emission tomography (PET) overlay on CT has shown to impact the gross target volume (GTV), decrease intraobserver variability, and change the treatment planning in a significant number of patients. The objective of this study was to evaluate the influence and accuracy of FDG PET in GTV definition as a complementary modality to CT for patients with non–small-cell lung carcinoma at Vanderbilt University Medical Center. Methods: Data from 11 consecutive patients with non–small-cell lung carcinoma, which were referred to FDG PET/CT for initial staging and RT planning were analyzed retrospectively. All patients had undergone routine staging using a RT noncontrasted CT. Both the RT CT and PET/CT images were acquired using standard protocols but with the patients positioned in the same RT immobilization devices. Both the CT and PET/CT images were transferred to the RT planning workstation for contouring. GTV, pathologic nodal and metastases volumes were first defined in the conventional manner based on RT CT. The FDG PET and RT CT planning image datasets were coregistered with the help of the transmission CT from PET/CT. FDG PET GTVs were determined by a team of radiation oncologists and nuclear physician with expertise in PET/CT, and displayed simultaneously with the CT contours. The RT CT and PET GTV were measured and the percent difference was calculated for the primary tumor, pathologic lymph nodes, and distant metastases. A difference of 15% was considered significant. Results: The primary tumor GTV was decreased in 36% (n = 4) of patients by differentiating atelectasis and postobstructive pneumonia from tumor, and increased GTV in 27% (n = 3) of patients by detecting additional tumor burden. Increased nodal disease burden was detected in 18% (n = 2) of patients. The use of PET/CT changed treatment from curative to palliative by detecting distant metastasis in 27% (n = 3) of patients. Conclusions: Our results are consistent with the published data of PET/CT altering GTV in a significant number of patients, detecting tumor spread to additional lymph nodes and distant metastases. While these advantages support the use of PET/CT in RT planning, it remains unknown what impact this will have on patient outcomes.

Heat Shock Protein 90 Promotes Epithelial to Mesenchymal Transition, Invasion, and Migration in Colorectal Cancer

Epithelial to mesenchymal transition (EMT), invasion, and motility are essential steps in colorectal cancer (CRC) metastasis regulated by HIF‐1α and NF‐κB. Since HSP90 activates HIF‐1α and NF‐κB, we hypothesized that inhibition of HSP90 leads to inhibition of HIF‐1α and NF‐κB resulting in inhibition of EMT, invasion, and motility. Treatment of colorectal cancer cell lines HT‐29 and HCT‐116 with ganetespib at 50 nM for 24 h inhibited EMT (downregulated vimentin and upregulated E‐cadherin), matrigel invasion, and spheroid migration. Ganetespib treatment or HSP90 knockdown downregulated molecular pathways associated with EMT, invasion, and motility. The overexpression of HIF‐1α or NF‐κB resulted in increased EMT, invasion, and motility in both cell lines and these effects were inhibited by ganetespib. Similar effects were observed in animal xenografts treated with ganetespib. Taken together, our data demonstrate for the first time that inhibition of HSP90 downregulates both HIF‐1α and NF‐κB leading to inhibition of EMT, motility, and invasiveness in colorectal cancer.