Theodore D. Chung

The application of the sinusoidal model to lung cancer patient respiratory motion

Accurate modeling of the respiratory cycle is important to account for the effect of organ motion on dose calculation for lung cancer patients. The aim of this study is to evaluate the accuracy of a respiratory model for lung cancer patients. Lujan et al. [Med. Phys. 26(5), 715-720 (1999)] proposed a model, which became widely used, to describe organ motion due to respiration. This model assumes that the parameters do not vary between and within breathing cycles. In this study, first, the correlation of respiratory motion traces with the model f(t) as a function of the parameter n (n = 1, 2, 3) was undertaken for each breathing cycle from 331 four-minute respiratory traces acquired from 24 lung cancer patients using three breathing types: free breathing, audio instruction, and audio-visual biofeedback. Because cos2 and cos4 had similar correlation coefficients, and cos2 and cos1 have a trigonometric relationship, for simplicity, the cos1 value was consequently used for further analysis in which the variations in mean position (z0), amplitude of motion (b) and period (tau) with and without biofeedback or instructions were investigated. For all breathing types, the parameter values, mean position (z0), amplitude of motion (b), and period (tau) exhibited significant cycle-to-cycle variations. Audio-visual biofeedback showed the least variations for all three parameters (z0, b, and tau). It was found that mean position (z0) could be approximated with a normal distribution, and the amplitude of motion (b) and period (tau) could be approximated with log normal distributions. The overall probability density function (pdf) of f(t) for each of the three breathing types was fitted with three models: normal, bimodal, and the pdf of a simple harmonic oscillator. It was found that the normal and the bimodal models represented the overall respiratory motion pdfs with correlation values from 0.95 to 0.99, whereas the range of the simple harmonic oscillator pdf correlation values was 0.71 to 0.81. This study demonstrates that the pdfs of mean position (z0), amplitude of motion (b), and period (tau) can be used for sampling to obtain more realistic respiratory traces. The overall standard deviations of respiratory motion were 0.48, 0.57, and 0.55 cm for free breathing, audio instruction, and audio-visual biofeedback, respectively.

EUS or percutaneously guided intratumoral TNFerade biologic with 5-fluorouracil and radiotherapy for first-line treatment of locally advanced pancreatic cancer: a phase I/II study

BACKGROUND TNFeradeBiologic (AdGVEGR.TNF.11D) is a replication-deficient adenoviral vector that expresses tumor necrosis factor-α (TNF-α) under the control of the Egr-1 promoter, which is inducible by chemotherapy and radiation. OBJECTIVE This study was conducted to determine the maximal tolerated dose of TNFeradeBiologic with standard chemoradiotherapy and preliminary activity and safety of the combination in the treatment of locally advanced pancreatic cancer (LAPC). DESIGN TNFeradeBiologic was injected into locally advanced pancreatic carcinomas by using EUS or percutaneous administration once a week for 5 weeks together with 50.4 Gy radiation and 5-fluorouracil (5-FU) 200 mg/m(2) daily over 5.5 weeks. Dose levels from 4 × 10(9) to 1 × 10(12) particle units (PU) were studied. SETTING Multicentered, academic institutions. PATIENTS Fifty patients with LAPC were treated. INTERVENTIONS Doses of TNFerade Biologic were administered to patients. MAIN OUTCOME MEASUREMENTS Toleration of TNFerade Biologic was measured through toxicity and tumor response, by using the criteria of the Response Evaluation Criteria in Solid Tumors and the World Health Organization, and was reviewed by a central radiology facility. Overall survival and progression-free survival were also measured. RESULTS Dose-limiting toxicities of pancreatitis and cholangitis were observed in 3 patients at the 1 × 10(12) PU dose, making 4 × 10(11) PU the maximum tolerated dose. One complete response, 3 partial responses, and 12 patients with stable disease were noted. Seven patients eventually went to surgery, 6 had clear margins, and 3 survived >24 months. LIMITATIONS This is a Phase 1/2 non-randomized study. CONCLUSIONS Intratumoral delivery of TNFerade Biologic by EUS with fine-needle viral injection or percutaneously, combined with chemoradiation, shows promise in the treatment of LAPC. There appeared to be better clinical outcome at the maximal tolerated dose than at lower doses. The dose of 4 ×10(11) PU TNFerade Biologic was generally well tolerated, with encouraging indications of activity, and will be tested in the randomized phase of this study. Delivery of TNFerade Biologic did not interfere with subsequent surgical resection.

Stereotactic body radiation therapy of lung tumors: preliminary experience using normal tissue complication probability-based dose limits.

Objectives:To assess the feasibility and toxicity of stereotactic body radiotherapy (SBRT) for patients with locally advanced or metastatic tumors in lung. Methods:Twenty-five tumors in 17 patients were treated. All treatments were delivered in 3 daily fractions of 9 to 15 Gy per fraction. Normal tissue complication probability (NTCP) calculations (using the Lyman model) were performed to facilitate dose prescription, and doses were prescribed with a maximum allowable NTCP risk of pneumonitis of up to 20%, not to exceed 15 Gy per fraction. Planning target volumes were designed to allow for respiratory variation in tumor location. Results:The median dose prescribed was 35 Gy (range, 24 to 45 Gy). Twenty-three of 25 tumors remained controlled at median follow-up of 14 months. Four patients experienced grade 1–2 acute toxicity. Late toxicity developed in 2 patients who received treatment to peri-hilar tumors, including one patient in whom bronchial stenosis developed with complete occlusion and lobar atelectasis 6 months after treatment. No patient had grade 3 or 4 radiation pneumonitis. Conclusions:SBRT prescribed within the confines of NTCP-restricted dosing on this protocol resulted in no radiation pneumonitis. Tissues other than lung parenchyma which are unaccounted for by NTCP may be dose-limiting when performing hypofractionated SBRT in the lung.

Inability of Transforming Growth Factor-β to Cause SnoN Degradation Leads to Resistance to Transforming Growth Factor-β–Induced Growth Arrest in Esophageal Cancer Cells

It is well established that loss of a growth inhibitory response to transforming growth factor-beta (TGF-beta) is a common feature of epithelial cancers including esophageal cancer. However, the molecular basis for the abrogation of this key homeostatic mechanism is poorly understood. In esophageal cancer cell lines that are resistant to TGF-beta-induced growth inhibition, TGF-beta also fails to decrease transcription of c-myc despite the presence of functional signaling components. Consequently, to gain a better understanding of the mechanisms leading to resistance to TGF-beta-induced growth arrest, the basis for the inability to decrease c-myc transcription was investigated. Regardless of sensitivity to TGF-beta-induced growth arrest, TGF-beta enhanced the ability of Smad3-protein complexes to bind c-myc regulatory elements. However, in a growth inhibition-resistant esophageal cancer cell line, the Smad3-protein complexes contained the SnoN oncoprotein. Furthermore, in esophageal cancer cell lines that are resistant to TGF-beta-induced growth arrest, TGF-beta does not cause degradation of SnoN. Analyses of the effect of modulating SnoN expression in both growth inhibition-sensitive and growth inhibition-resistant cell lines showed that degradation of SnoN is a prerequisite for both TGF-beta-induced repression of c-myc transcription and growth arrest. The data indicate that SnoN-Smad3 complexes do not cause repression of c-myc transcription but rather prevent functionality of active repressor complexes. Thus, these studies reveal a novel mechanism for resistance to TGF-beta-induced growth inhibition in esophageal cancer, namely the failure to degrade SnoN. In addition, they show that SnoN can block TGF-beta repression of gene transcription.

Investigation of patient, tumour and treatment variables affecting residual motion for respiratory-gated radiotherapy.

Respiratory gating can reduce the apparent respiratory motion during imaging and treatment; however, residual motion within the gating window remains. Respiratory training can improve respiratory reproducibility and, therefore, the efficacy of respiratory-gated radiotherapy. This study was conducted to determine whether residual motion during respiratory gating is affected by patient, tumour or treatment characteristics. The specific aims of this study were to: (1) identify significant characteristics affecting residual motion, (2) investigate time trends of residual motion over a period of days (inter-session) and (3) investigate time trends of residual motion within the same day (intra-session). Twenty-four lung cancer patients were enrolled in an Institutional Review Board (IRB)-approved protocol. For approximately five sessions, 331 four-minute, respiratory motion traces were acquired with free breathing, audio instructions and audio-visual biofeedback for each patient. The residual motion was quantified by the standard deviation of the displacement within the gating window. The generalized linear model was used to obtain coefficients for each variable within the model and to evaluate the clinical and statistical significance. The statistical significance was determined by a p-value<0.05, while effect sizes of 0.1 cm (one standard deviation) were considered clinically significant. This data analysis was applied to patient, tumour and treatment variables. Inter- and intra-session variations were also investigated. The only variable that was significant for both inhale- and exhale-based gating was disease type. In addition, visual-training displacement, breathing type and Karnofsky performance status (KPS) values were significant for inhale-based gating, and dose-per-fraction was significant for exhale-based gating. Temporal respiratory variations within and between sessions were observed for individual patients. However inter- and intra-session analyses did not show significant time trends on average for any of the variables considered. The lack of significant time trends within and between sessions indicates that on average (1) there is no significant learning period for breathing training, (2) the patients did not experience training-related fatigue and (3) the margin component to account for residual motion during gated radiotherapy appears to remain constant throughout the treatment.

A Novel Gene Transfer Therapy Against Pancreatic Cancer (TNFerade) Delivered by Endoscopic Ultrasound (EUS) and Percutaneous Guided Fine Needle Injection (FNI)

A Novel Gene Transfer Therapy Against Pancreatic Cancer (TNFerade) Delivered by Endoscopic Ultrasound (EUS) and Percutaneous Guided Fine Needle Injection (FNI) Kenneth J. Chang, Neil Senzer, Theodore Chung, J. Randolph Hecht, Stephen Vogel, Alexander Rosemurgy, John Nemunaitis, John Gibbs, Milind Javle, Tony Reid, Jennifer Macko, Paul Kessler, Mitchell C. Posner, James Farrell, L. Shane Grundy, Roy Soetikno, Irving Waxman, Nader Hanna We published two trials utilizing EUS-guided FNI for the delivery of immune therapy (Cancer 2000) and oncolytic viral therapy (Clin Cancer Res 2003) against pancreatic cancer. We now present a novel gene transfer therapy, TNFerade, delivered by EUS and percutaneous approaches (PTA) guided by ultrasound or computerized tomography (CT), in the treatment of unresectable, locally advanced adenocarcinoma of the pancreas (LAPC). TNFerade is a replicationdeficient adenovector containing human TNFa gene, regulated by a radiationinducible promoter Egr-1. Purpose: 1) Assess safety and efficacy of TNFerade plus chemoradiation in pts with LAPC. 2) Compare EUS and PTA as delivery modalities. Methods: Dose-escalating run-in design. Five-week treatment of weekly intratumoral injections of TNFerade (43 10 particle units (pu) in 2mL) via EUS or PTA (each institution allowed one preferred technique), continuous iv 5-FU (200 mg/m/d 3 5 days/wk) and radiation (50.4 Gy). TNFerade was delivered with a single needle pass at a single site in the tumor for PTA, while up to 4 injections were given by EUS. Endpoints: Safety and tumor response on spiral CT (core lab). Results: Of 37 pts, 17 had EUS and 20 had PTA (similar TNFerade doses). EUS vs PTA: T4 staging = 88% vs. 75%; N1 staging = 29% vs. 40%, mean tumor area (cm)= 18 vs.19; mean CA19-9= 4,396 vs. 1,707, meanKPS= 88 vs. 90. (p=NS for all). 1 dose limiting toxicity (gr 3 hypotension) in a PTApt; all other adverse events (AEs) potentially related to TNFerade were grade 1-2. Procedure related AEs were all grade 1-2 and were similar, except for injection site pain: 35% PTA vs 0% EUS (p = .01). Tumor responses and disease control were similar (Table 1). 4 patients underwent resection; one, an EUS patient, had a complete pathologic response. Conclusions: 1) TNFerade plus chemoradiation was well tolerated with maximum tolerated dose not reached; 2) indications of clinical activity were demonstrated by local tumor control and progression-free survival at up to 3 months; 3) EUS and PTA appear to be similarly safe and effective for delivery of TNFerade.

The effects of pentoxifylline on the survival of human glioma cells with continuous and intermittent stereotactic radiosurgery irradiation.

PURPOSE In linac-based stereotactic radiosurgery, treatment is delivered intermittently via multiple individual small radiotherapy arcs. The time lapses between the individual arcs permit greater damage repair and increased tumor cell survival in comparison with continuous irradiation. Because pentoxifylline (PTX) has been reported to prevent radiation-induced cell cycle arrest at the G2/M checkpoint, where damage repair is critically linked to cell survival, we hypothesized that PTX would exert a favorable radiosensitization effect by reducing the recovery observed during intermittent stereotactic radiosurgery. METHODS AND MATERIALS The human glioma cell line T98G was used to study the effects of continuous vs. intermittent irradiation with or without PTX. Cell cycle patterns were studied using flow cytometry. Clonogenic assays of single cells and spheroid outgrowth assays provided a quantitative measure of PTX-mediated radiosensitization. The PTX effect upon cells in low oxygen conditions was also studied in vitro after enzymatic oxygen scavenging. RESULTS Flow Cytometry: T98G cells exposed to both continuous and intermittent irradiation exhibit similar arrest at the G2/M checkpoint. The addition of 2 mM PTX significantly reduced the radiation-induced G2/M block in both irradiation schemes. Clonogenic Assays: The same PTX concentration applied before a continuous dose of 12 Gy, two intermittent doses of 6 Gy, or three intermittent doses of 4 Gy, all given within a 1-h interval, consistently caused radiosensitization. The drug enhancement ratios for PTX were 1.5, 2.7, and 6.0 for the continuous and two different intermittent dose schedules, respectively. Adding PTX after irradiation yielded lower enhancement ratios than pre-irradiation application. A similar pattern was observed after total doses of 4, 6, 9, or 12 Gy, as well. In low oxygen conditions, PTX was seen to have the same effects as in normoxic conditions. Spheroid Outgrowth Assays: The in vitro PTX effects were replicated in the spheroid outgrowth assays. CONCLUSION In human glioma cells, PTX abrogates the radiation-induced G2/M block observed after either continuous radiation exposure or intermittent exposures modeling clinical linac-based radiosurgery. The PTX-mediated reduction of the G2/M block translates into radiosensitization, most notably during intermittent exposures, and is presumably a consequence of diminished DNA damage repair at the G2/M checkpoint, though other contributing effects cannot be ruled out. The radiosensitization effect of PTX is sustained under low oxygen conditions. These results support consideration of the clinical evaluation of PTX to enhance the efficacy of linac-based radiosurgery involving intermittent irradiation through multiple arcs.

The Influence of Hypoxia and pH on Bioluminescence Imaging of Luciferase-Transfected Tumor Cells and Xenografts

Bioluminescence imaging (BLI) is a relatively new noninvasive technology used for quantitative assessment of tumor growth and therapeutic effect in living animal models. BLI involves the generation of light by luciferase-expressing cells following administration of the substrate luciferin in the presence of oxygen and ATP. In the present study, the effects of hypoxia, hypoperfusion, and pH on BLI signal (BLS) intensity were evaluated in vitro using cultured cells and in vivo using a xenograft model in nude mice. The intensity of the BLS was significantly reduced in the presence of acute and chronic hypoxia. Changes in cell density, viability, and pH also affected BLS. Although BLI is a convenient non-invasive tool for tumor assessment, these factors should be considered when interpreting BLS intensity, especially in solid tumors that could be hypoxic due to rapid growth, inadequate blood supply, and/or treatment.

Tumor control probability predictions for genetic radiotherapy.

PURPOSE Genetic radiotherapy, the combination of gene therapy and radiation therapy, for cancer treatment is evolving from laboratory studies to clinical trials. Genetic radiotherapy involves the viral infection of cells that change the sensitivity of transduced cells to radiation. Because there is no patient outcome data for genetic radiotherapy, prospective models are needed to determine the expected benefit of this new modality. Such a prospective model has been developed in this work. METHODS AND MATERIALS An existing tumor control probability (TCP) calculation model developed for external beam radiotherapy was modified for genetic radiotherapy. Specifically, the (1) transduced fraction and (2) enhancement factor of the transduced cells were included in the model. Parametric studies of the effects of these two variables on TCP for head-and-neck cancer were performed. RESULTS Using reasonable transduction fraction and enhancement factor values (0.8 and 1.4, respectively), the model predicts an increase in the TCP for genetic radiotherapy over radiotherapy alone by up to 15% for the same radiotherapy dose. The theoretical limit of TCP increase was calculated to be near 70%, which may occur with improved techniques that increase the transduced fraction or because of a strong bystander effect. To maintain existing TCP, dose reductions from 5 Gy (reasonable values) to >30 Gy (ideal case) are predicted for genetic radiotherapy over radiotherapy alone. CONCLUSIONS Our results indicate that genetic radiotherapy has the potential to significantly improve tumor control over radiotherapy alone.

Safety and efficacy of TNFerade in unresectable, locally advanced pancreatic cancer (LAPC): Results of the first three cohorts of a dose-escalating study

3038 Background: TNFerade is a replication-deficient adenovector containing the TNF-α gene regulated by a radiation-inducible promoter Egr-1. This dose-escalating study evaluated the safety and early efficacy of TNFerade + chemoradiation in patients with locally advanced, unresectable pancreatic cancer (LAPC). METHODS A standard dose-escalating design with three dosing levels was used. Five-week treatment consisted of weekly intratumoral injections of 2 ml TNFerade, continuous infusion 5-FU and 50.4 Gy radiation. TNFerade was administered via either percutaneous transabdominal approach or endoscopic ultrasound. The route of administration was based on site preference. ENDPOINTS Safety, radiographic tumor response. A standardized imaging protocol with all studies assessed by an independent core lab. RESULTS 37 patients were enrolled. Baseline characteristics for the 4x109 pu (n=10), 4x1010 pu (n=20), and 4x1011 pu (n=7) groups, respectively: mean tumor size (cm2) = 23, 16, 19; and mean CA19-9 (pg/mL) =5,717, 1,374, 3,462. One dose limiting toxicity (hypotension, grade 3) occurred in a PTA patient at 4x1010 pu, who was subsequently able to resume treatment; all other adverse events potentially related to TNFerade were grade 1-2, and were most commonly fever (27%), fatigue (19%) and rigors (19%). The 4x1011 pu dose was associated with 100% locoregional control of treated tumors, greater survival without progression, and a greater proportion of patients with stable or decreasing CA19-9, as compared to the other doses at 3 months post treatment (table). Four of 6 patients that were surgically explored underwent resection, one was a complete pathologic response. CONCLUSIONS TNFerade combined with chemotherapy shows promise in treatment of LAPC. Increased doses beyond 4 x 1011 may be feasible. Randomized studies are warranted. [Figure: see text] [Table: see text].