Paul W. Read

Rho kinase and matrix metalloproteinase inhibitors cooperate to inhibit angiogenesis and growth of human prostate cancer xenotransplants

The purpose of this study was to determine the effects of inhibitors of Rho kinase (ROK) and matrix metalloproteinases (MMPs) on angiogenesis and tumor growth and to evaluate ROK activity in human prostate cancer PC3 cells and endothelial cells (HUVECs). Vacuolation by endothelial cells and lumen formation, the earliest detectable stages of angiogenesis, were inhibited by the ROK inhibitor Wf‐536. Combining Wf‐536 with the MMP inhibitor Marimastat greatly enhanced in vitro inhibition of endothelial vacuolation, lumen and cord formation, and VEGF‐ and HGF‐stimulated endothelial sprout formation from aorta. Inhibition of sprout formation by the two inhibitors was synergistic. Both agents inhibited migration of HUVECs. The regulatory subunit (MYPT1) of the myosin phosphatase was phosphorylated in PC3 cells and HUVECs, and phosphorylation of MYPT1 and the myosin regulatory light chain was reduced by Wf‐536, providing direct evidence of ROK activity. Early treatment of immuno‐incompetent mice bearing xenotrans‐plants of PC3 cells with a combination of Wf‐536 plus Marimastat with or without Paclitaxel, significantly inhibited tumor growth, prevented tumor growth escape after discontinuation of Paclitaxel, and increased survival.—Somlyo, A. V., Phelps, C., Dipierro, C., Eto, M., Read, P., Barrett, M., Gibson, J. J., Burnitz, M. C., Myers, C., Somlyo, A. P. Rho kinase and matrix metalloproteinase inhibitors cooperate to inhibit angiogenesis and growth of human prostate cancer xenotransplants. FASEB J. 17, 223–234 (2003)

Size matters: a comparison of T1 and T2 peripheral non-small-cell lung cancers treated with stereotactic body radiation therapy (SBRT).

OBJECTIVE The purpose of this study was to compare the outcomes and local control rates of patients with peripheral T1 and T2 non-small-cell lung cancer treated with stereotactic body radiation therapy. METHODS The records of 40 consecutive patients treated with 3- or 5-fraction lung stereotactic body radiation therapy for peripheral, clinical stage I non-small-cell lung cancer were reviewed. Stereotactic body radiation therapy was delivered at a median dose of 60 Gy. Doses to organs at risk were limited based on the Radiation Therapy Oncology Group 0236 treatment protocol. Patients were staged clinically. Median follow was 12.5 months. RESULTS Twenty-seven (67%) patients and 13 (33%) patients had T1 and T2 tumors, respectively. Thirty-seven (94%) patients were medically inoperable. Nine (23%) patients had chest wall pain after stereotactic body radiation therapy. Symptomatic pneumonitis developed in 4 (10%) patients. Increasing tumor size correlated with worse local control and overall survival. The median recurrence-free survival for T1 and T2 tumors was 30.6 months (95% confidence interval [CI], 26.9-34.2) and 20.5 months (95% CI, 14.3-26.5), respectively (P = .038). Local control at 2 years was 90% and 70% in T1 and T2 tumors, respectively (P = .03). The median survival for T1 and T2 tumors was 20 months (95% CI, 20.1-31.6) and 16.7 months (95% CI, 10.8-21.2), respectively (P = .073). CONCLUSIONS Stereotactic body radiation therapy for T2 non-small-cell lung cancer has a higher local recurrence rate and trended toward a worse survival than did T1 lesions. Tumor size is an important predictor of response to stereotactic body radiation therapy and should be considered in treatment planning.

PREIRRADIATION PSA PREDICTS BIOCHEMICAL DISEASE-FREE SURVIVAL IN PATIENTS TREATED WITH POSTPROSTATECTOMY EXTERNAL BEAM IRRADIATION

PURPOSE To assess the clinical outcome and prostate-specific antigen (PSA) response and to determine prognostic factors for biochemical disease-free survival in patients treated with external beam radiotherapy following radical prostatectomy without hormonal therapy. METHODS AND MATERIALS Forty-eight patients were treated after prostatectomy with radiotherapy between March, 1988 and December, 1993. Seven patients had undetectable PSA (<0.2) and the remainder had detectable PSA at the time of irradiation (overall: median 2.7, range 0-24.9). Nine patients had biopsy proven local recurrence, palpable local disease, or positive preirradiation imaging. No patients received hormonal therapy prior to irradiation. Median follow-up was 55 months. A median dose of 60 Gy (range 58-66) was given to the prostate bed. Survival was analyzed using the life-table method. Actuarial biochemical disease-free survival was the primary endpoint studied. RESULTS In patients with detectable PSA, 51% had levels return to undetectable after irradiation. The actuarial 5-year freedom from biochemical failure for all patients was 24%. A significant difference in biochemical disease-free survival was seen for patients irradiated with preirradiation PSA that was undetectable (p < 0.001), or preirradiation PSA that was < or =2.7 (p = 0.002), vs. preirradiation PSA that was >2.7. Five-year actuarial biochemical disease-free survival values were 71, 48, and 0%, respectively, for the three groups. Biochemical disease-free survival was not affected by preoperative PSA level, clinical stage, Gleasons score, pathologic stage, surgical margins, presence of undetectable PSA after surgery, surgery to radiation interval, total dose, or presence of clinically suspicious local disease. Based on digital rectal exam, there were no local failures. CONCLUSION Biochemical disease-free survival after postprostatectomy radiation is predicted by the PSA at the time of irradiation. Clinical local control is excellent, but distant failure remains a significant problem in this population. The addition of concomitant systemic therapy should be investigated in patients with PSA >2.7.

How RhoGDI binds Rho

Like all Rho (Ras homology) GTPases, RhoA functions as a molecular switch in cell signaling, alternating between GTP- and GDP-bound states, with its biologically inactive GDP-bound form maintained as a cytosolic complex with RhoGDI (guanine nucleotide-exchange inhibitor). The crystal structures of RhoA-GDP and of the C-terminal immunoglobulin-like domain of RhoGDI (residues 67-203) are known, but the mechanism by which the two proteins interact is not known. The functional human RhoA-RhoGDI complex has been expressed in yeast and crystallized (P6(5)22, unit-cell parameters a = b = 139, c = 253 A, two complexes in the asymmetric unit). Although diffraction from these crystals extends to 3.5 A and is highly anisotropic, the experimentally phased (MAD plus MIR) electron-density map was adequate to reveal the mutual disposition of the two molecules. The result was validated by molecular-replacement calculations when data were corrected for anisotropy. Furthermore, the N-terminus of RhoGDI (the region involved in inhibition of nucleotide exchange) can be identified in the electron-density map: it is bound to the switch I and switch II regions of RhoA, occluding an epitope which binds Dbl-like nucleotide-exchange factors. The entrance of the hydrophobic pocket of RhoGDI is 25 A from the last residue in the RhoA model, with its C-terminus oriented to accommodate the geranylgeranyl group without conformational change in RhoA.

Computed tomography-based anatomic assessment overestimates local tumor recurrence in patients with mass-like consolidation after stereotactic body radiotherapy for early-stage non-small cell lung cancer.

PURPOSE To investigate pulmonary radiologic changes after lung stereotactic body radiotherapy (SBRT), to distinguish between mass-like fibrosis and tumor recurrence. METHODS AND MATERIALS Eighty consecutive patients treated with 3- to 5-fraction SBRT for early-stage peripheral non-small cell lung cancer with a minimum follow-up of 12 months were reviewed. The mean biologic equivalent dose received was 150 Gy (range, 78-180 Gy). Patients were followed with serial CT imaging every 3 months. The CT appearance of consolidation was defined as diffuse or mass-like. Progressive disease on CT was defined according to Response Evaluation Criteria in Solid Tumors 1.1. Positron emission tomography (PET) CT was used as an adjunct test. Tumor recurrence was defined as a standardized uptake value equal to or greater than the pretreatment value. Biopsy was used to further assess consolidation in select patients. RESULTS Median follow-up was 24 months (range, 12.0-36.0 months). Abnormal mass-like consolidation was identified in 44 patients (55%), whereas diffuse consolidation was identified in 12 patients (15%), at a median time from end of treatment of 10.3 months and 11.5 months, respectively. Tumor recurrence was found in 35 of 44 patients with mass-like consolidation using CT alone. Combined with PET, 10 of the 44 patients had tumor recurrence. Tumor size (hazard ratio 1.12, P=.05) and time to consolidation (hazard ratio 0.622, P=.03) were predictors for tumor recurrence. Three consecutive increases in volume and increasing volume at 12 months after treatment in mass-like consolidation were highly specific for tumor recurrence (100% and 80%, respectively). Patients with diffuse consolidation were more likely to develop grade ≥ 2 pneumonitis (odds ratio 26.5, P=.02) than those with mass-like consolidation (odds ratio 0.42, P=.07). CONCLUSION Incorporating the kinetics of mass-like consolidation and PET to the current criteria for evaluating posttreatment response will increase the likelihood of correctly identifying patients with progressive disease after lung SBRT.

A motion phantom study on helical tomotherapy: the dosimetric impacts of delivery technique and motion

Helical tomotherapy (HT) can potentially be used for lung cancer treatment including stereotactic radiosurgery because of its advanced image guidance and its ability to deliver highly conformal dose distributions. However, previous theoretical and simulation studies reported that the effect of respiratory motion on statically planned tomotherapy treatments may cause substantial differences between the calculated and actual delivered radiation isodose distribution, particularly when the treatment is hypofractionated. In order to determine the dosimetric effects of motion upon actual HT treatment delivery, phantom film dosimetry measurements were performed under static and moving conditions using a clinical HT treatment unit. The motion phantom system was constructed using a programmable motor, a base, a moving platform and a life size lung heterogeneity phantom with wood inserts representing lung tissue with a 3.0 cm diameter spherical tumour density equivalent insert. In order to determine the effects of different motion and tomotherapy delivery parameters, treatment plans were created using jaw sizes of 1.04 cm and 2.47 cm, with incremental gantry rotation periods between the minimum allowed (10 s) and the maximum allowed (60 s). The couch speed varied from 0.009 cm s(-1) to 0.049 cm s(-1), and delivered to a phantom under static and dynamic conditions with peak-to-peak motion amplitudes of 1.2 cm and 2 cm and periods of 3 and 5 s to simulate human respiratory motion of lung tumours. A cylindrical clinical target volume (CTV) was contoured to tightly enclose the tumour insert. 2.0 Gy was prescribed to 95% of the CTV. Two-dimensional dose was measured by a Kodak EDR2 film. Dynamic phantom doses were then quantitatively compared to static phantom doses in terms of axial dose profiles, cumulative dose volume histograms (DVH), percentage of CTV receiving the prescription dose and the minimum dose received by 95% of the CTV. The larger motion amplitude resulted in more under-dosing at the ends of the CTV in the axis of motion, and this effect was greater for the smaller jaw size plans. Due to the size of the penumbra, the 2.47 cm jaw plans provide adequate coverage for smaller amplitudes of motion, +/-0.6 cm in our experiment, without adding any additional margin in the axis of motion to the treatment volume. The periodic heterogeneous patterns described by previous studies were not observed from the single fraction of the phantom measurement. Besides the jaw sizes, CTV dose coverage is not significantly dependent on machine and phantom motion periods. The lack of adverse synchronization patterns from both results validate that HT is a safe technique for treating moving target and hypofractionation.

QUANTIFYING THE REPRODUCIBILITY OF HEART POSITION DURING TREATMENT AND CORRESPONDING DELIVERED HEART DOSE IN VOLUNTARY DEEP INHALATION BREATH HOLD FOR LEFT BREAST CANCER PATIENTS TREATED WITH EXTERNAL BEAM RADIOTHERAPY

PURPOSE Voluntary deep inhalation breath hold (VDIBH) reduces heart dose during left breast irradiation. We present results of the first study performed to quantify reproducibility of breath hold using bony anatomy, heart position, and heart dose for VDIBH patients at treatment table. METHODS AND MATERIALS Data from 10 left breast cancer patients undergoing VDIBH whole-breast irradiation were analyzed. Two computed tomography (CT) scans, free breathing (FB) and VDIBH, were acquired to compare dose to critical structures. Pretreatment weekly kV orthogonal images and tangential ports were acquired. The displacement difference from spinal cord to sternum across the isocenter between coregistered planning Digitally Reconstructed Radiographs (DRRs) and kV imaging of bony thorax is a measure of breath hold reproducibility. The difference between bony coregistration and heart coregistration was the measured heart shift if the patient is aligned to bony anatomy. RESULTS Percentage of dose reductions from FB to VDIBH: mean heart dose (48%, SD 19%, p = 0.002), mean LAD dose (43%, SD 19%, p = 0.008), and maximum left anterior descending (LAD) dose (60%, SD 22%, p = 0.008). Average breath hold reproducibility using bony anatomy across the isocenter along the anteroposterior (AP) plane from planning to treatment is 1 (range, 0-3; SD, 1) mm. Average heart shifts with respect to bony anatomy between different breath holds are 2 ± 3 mm inferior, 1 ± 2 mm right, and 1 ± 3 mm posterior. Percentage dose changes from planning to delivery: mean heart dose (7%, SD 6%); mean LAD dose, ((9%, SD 7%)S, and maximum LAD dose, (11%, SD 11%) SD 11%, p = 0.008). CONCLUSION We observed excellent three-dimensional bony registration between planning and pretreatment imaging. Reduced delivered dose to heart and LAD is maintained throughout VDIBH treatment.

Effect of oral nutritional supplementation on weight loss and percutaneous endoscopic gastrostomy tube rates in patients treated with radiotherapy for oropharyngeal carcinoma

GoalsMalnutrition in the head and neck cancer population is a widely recognized factor contributing to negative outcomes. The goal of this study was to determine if providing complimentary oral nutritional supplementation for patients undergoing definitive radiation therapy for oropharyngeal carcinoma reduced weight loss and the need for percutaneous endoscopic gastrostomy (PEG) tube placement.Materials and methodsThe data from 79 patients undergoing radiotherapy for oropharyngeal cancer were extracted and analyzed retrospectively from an institutional Human Investigation Committee approved database for the study of advanced radiation therapy techniques for head and neck cancer. Forty patients were treated before the initiation of a nutritional supplementation program, and 39 patients received supplementation. Patients were stratified by type of treatment (radiation alone or chemoradiation) and whether or not they had a PEG tube.ResultsAll patient groups receiving supplementation manifested a significant decrease in weight loss compared to those who did not receive it. Nutritional supplementation was associated with a 40% relative reduction in weight loss in patients treated with radiotherapy alone (6.1 vs 10.1%, p = 0.008) and a 37% reduction in weight loss in patients treated with chemoradiotherapy (6.7 vs 10.7%, p = 0.007). When patients were stratified by the presence or absence of a PEG tube, both groups experienced a 39% relative reduction in weight loss (with PEG, 5.7 vs 9.3%, p = 0.028; without PEG, 6.9 vs 11.2%, p = 0.002). Supplementation was associated with a decreased need for PEG tube placement (31% decreased to 6%) in patients treated with radiotherapy alone.ConclusionsProviding complimentary oral nutritional supplementation significantly decreases weight loss and the need for PEG tube placement in patients undergoing radiation therapy for oropharyngeal cancer.

The effect of respiratory motion variability and tumor size on the accuracy of average intensity projection from four-dimensional computed tomography: An investigation based on dynamic MRI

Composite images such as average intensity projection (AIP) and maximum intensity projection (MIP) derived from four-dimensional computed tomography (4D-CT) images are commonly used in radiation therapy for treating lung and abdominal tumors. It has been reported that the quality of 4D-CT images is influenced by the patient respiratory variability, which can be assessed by the standard deviation of the peak and valley of the respiratory trajectory. Subsequently, the resultant MIP underestimates the actual tumor motion extent. As a more general application, AIP comprises not only the tumor motion extent but also the probability that the tumor is present. AIP generated from 4D-CT can also be affected by the respiratory variability. To quantitate the accuracy of AIP and develop clinically relevant parameters for determining suitability of the 4D-CT study for AIP-based treatment planning, real time sagittal dynamic magnetic resonance imaging (dMRI) was used as the basis for generating simulated 4D-CT. Five-minute MRI scans were performed on seven healthy volunteers and eight lung tumor patients. In addition, images of circular phantoms with diameter 1, 3, or 5 cm were generated by software to simulate lung tumors. Motion patterns determined by dMRI images were reproduced by the software generated phantoms. Resorted dMRI using a 4D-CT acquisition method (RedCAM) based on phantom or patient images was reconstructed by simulating the imaging rebinning processes. AIP images and the corresponding color intensity projection (CIP) images were reconstructed from RedCAM and the full set of dMRI for comparison. AIP similarity indicated by the Dice index between RedCAM and dMRI was calculated and correlated with respiratory variability (v) and tumor size (s). The similarity of percentile intrafractional motion target area (IMTA), defined by the area that the tumor presented for a given percentage of time, and MIP-to-percentile IMTA similarity as a function of percentile were also determined. As a result, AIP similarity depends on both respiratory variability and tumor sizes. The AIP similarity correlated linearly with the respiratory variability normalized by tumor sizes (R2 equal to 0.82 and 0.91 for the phantom study and the patient study, respectively). For both studies, MIP derived from RedCAM was close to the area that the tumor presented 90% or more of the time and missed the region where the tumor appeared less than 10% of the time. In conclusion, the accuracy of composite images such as AIP and MIP derived from 4D-CT to define the tumor motion and position is affected by patient-specific respiratory variability and tumor sizes. Based on our study, normalized respiratory variability appears to be a pertinent parameter to assess the suitability of a 4D-CT image set for ALP-based treatment planning.

Intensity‐modulated radiotherapy outcomes for oropharyngeal squamous cell carcinoma patients stratified by p16 status

Patients with oropharyngeal squamous cell carcinoma (OPSCC) treated with intensity‐modulated radiotherapy (IMRT) were stratified by p16 status, neck dissection, and chemotherapy to correlate these factors with outcomes.