Matthew Hardee

Combination of Gold Nanoparticle-Conjugated Tumor Necrosis Factor-α and Radiation Therapy Results in a Synergistic Antitumor Response in Murine Carcinoma Models.

PURPOSE Although remarkable preclinical antitumor effects have been shown for tumor necrosis factor-α (TNF) alone and combined with radiation, its clinical use has been hindered by systemic dose-limiting toxicities. We investigated the physiological and antitumor effects of radiation therapy combined with the novel nanomedicine CYT-6091, a 27-nm average-diameter polyethylene glycol-TNF-coated gold nanoparticle, which recently passed through phase 1 trials. METHODS AND MATERIALS The physiologic and antitumor effects of single and fractionated radiation combined with CYT-6091 were studied in the murine 4T1 breast carcinoma and SCCVII head and neck tumor squamous cell carcinoma models. RESULTS In the 4T1 murine breast tumor model, we observed a significant reduction in the tumor interstitial fluid pressure (IFP) 24 hours after CYT-6091 alone and combined with a radiation dose of 12 Gy (P<.05 vs control). In contrast, radiation alone (12 Gy) had a negligible effect on the IFP. In the SCCVII head and neck tumor model, the baseline IFP was not markedly elevated, and little additional change occurred in the IFP after single-dose radiation or combined therapy (P>.05 vs control) despite extensive vascular damage observed. The IFP reduction in the 4T1 model was also associated with marked vascular damage and extravasation of red blood cells into the tumor interstitium. A sustained reduction in tumor cell density was observed in the combined therapy group compared with all other groups (P<.05). Finally, we observed a more than twofold delay in tumor growth when CYT-6091 was combined with a single 20-Gy radiation dose-notably, irrespective of the treatment sequence. Moreover, when hypofractionated radiation (12 Gy × 3) was applied with CYT-6091 treatment, a more than five-fold growth delay was observed in the combined treatment group of both tumor models and determined to be synergistic. CONCLUSIONS Our results have demonstrated that TNF-labeled gold nanoparticles combined with single or fractionated high-dose radiation therapy is effective in reducing IFP and tumor growth and shows promise for clinical translation.

Application of Spatially Fractionated Radiation (GRID) to Helical Tomotherapy using a Novel TOMOGRID Template

Spatially fractionated radiation therapy (GRID) with megavoltage x-ray beam is typically used to treat large and bulky malignant tumors. Currently most of the GRID treatment is performed by using the linear accelerator with either the multileaf collimator or with the commercially available block. A novel method to perform GRID treatments using Helical Tomotherapy (HT) was developed at the Radiation Oncology Department, College of Medicine, the University of Arkansas for Medical Sciences. In this study, we performed a dosimetric comparison of two techniques of GRID therapy: one on linear accelerator with a commercially available GRID block (LINAC-GRID) as planned on the Pinnacle planning station (P-TPS); and helical tomotherapy-based GRID (HT-GRID) technique using a novel virtual TOMOGRID template planned on Tomotherapy treatment planning station (HT-TPS). Three dosimetric parameters: gross target volume (GTV) dose distribution, GTV target dose inhomogeneity, and doses to regions of interest were compared. The comparison results show that HT-GRID dose distributions are comparable to those of LINAC-GRID for GTV coverage. Doses to the majority of organs-at-risk (OAR) are lower in HT-GRID as compared to LINAC-GRID. The maximum dose to the normal tissue is reduced by 120% for HT-GRID as compared to the LINACGRID. This study indicate that HT-GRID can be used to deliver spatially fractionated dose distributions while allowing 3-D optimization of dose to achieve superior sparing of OARs and confinement of high dose to target.

Long-Term Results of Phase II Ablation after Breast Lumpectomy Added to Extend Intraoperative Margins (ABLATE l) Trial

BACKGROUND Excision followed by radiofrequency ablation (eRFA) is an intraoperative method that uses intracavitary hyperthermia to create an additional tumor-free zone around the lumpectomy cavity in breast cancer patients. We hypothesized that eRFA after lumpectomy for invasive breast cancer could reduce the need for re-excision for close margins as well as potentially maintain local control without the need for radiation. STUDY DESIGN This prospective phase II institutional review board-approved study was conducted from March 2004 to April 2010. A standard lumpectomy was performed, then the RFA probe was deployed 1 cm circumferentially into the walls of the lumpectomy cavity and maintained at 100 °C for 15 minutes. Validated Doppler sonography was used to intraoperatively determine adequacy of ablation. RESULTS One hundred patients were accrued to the trial, with an average age of 65.02 years ± 10.0 years. The stages were Tis (n = 30); T1mic (n = 1); T1a (n = 9); T1b (n = 27); T1c (n = 22); T2 (n = 10) ; and T3 (n = 1). Grades were I (n = 48); II (n = 29); and III (n = 23). Seventy-eight subjects had margins >2 mm (negative), 22 patients had margins ≤ 2 mm, of which 12 were close and 3 focally positive, which, at our institution, would have required re-excision (only 1 patient in this group had re-excision). There were 6% postoperative complications, and 24 patients received radiation therapy (XRT). During the study mean follow-up period of 62 months ± 24 months (68-month median follow-up) in patients not treated with XRT, there were 2 in-site tumor recurrences treated with aromitase inhibitor, 3 biopsy entrance site recurrences treated with excision and XRT to conserve the breast, and 2 recurrences elsewhere and 1 contralateral recurrence; all 3 treated with mastectomy. CONCLUSIONS Long-term follow-up suggests that eRFA may reduce the need for re-excision for close or focally positive margins in breast cancer patients, and eRFA may be a valuable tool for treating favorable patients who desire lumpectomy and either cannot or do not want radiation. A multicenter trial has been initiated based on these results.

Targeting Artificial Tumor Stromal Targets for Molecular Imaging of Tumor Vascular Hypoxia

Developed and tested for many years, a variety of tumor hypoxia detection methods have been inconsistent in their ability to predict treatment outcomes or monitor treatment efficacy, limiting their present prognostic capability. These variable results might stem from the fact that these approaches are based on inherently wide-ranging global tumor oxygenation levels based on uncertain influences of necrotic regions present in most solid tumors. Here, we have developed a novel non-invasive and specific method for tumor vessel hypoxia detection, as hypoxemia (vascular hypoxia) has been implicated as a key driver of malignant progression, therapy resistance and metastasis. This method is based on high-frequency ultrasound imaging of α-pimonidazole targeted-microbubbles to the exogenously administered hypoxia marker pimonidazole. The degree of tumor vessel hypoxia was assessed in three mouse models of mammary gland carcinoma (4T1, SCK and MMTV-Wnt-1) and amassed up to 20% of the tumor vasculature. In the 4T1 mammary gland carcinoma model, the signal strength of α-pimonidazole targeted-microbubbles was on average 8-fold fold higher in tumors of pimonidazole-injected mice than in non-pimonidazole injected tumor bearing mice or non-targeted microbubbles in pimonidazole-injected tumor bearing mice. Overall, this provides proof of principle for generating and targeting artificial antigens able to be ‘created’ on-demand under tumor specific microenvironmental conditions, providing translational diagnostic, therapeutic and treatment planning potential in cancer and other hypoxia-associated diseases or conditions.

A case of cutaneous Rosai-Dorfman disease (CRDD) with underlying calvarial involvement and absence of BRAFV600E mutation

Rosai-Dorfman disease (RDD) is a benign histiocytic proliferation that most commonly presents with painless bilateral lymphadenopathy and constitutional symptoms such as fever, fatigue, and night sweats.1 RDD is considered by many to be a reaction pattern with several different manifestations, especially as clonality has not been documented to support it representing a neoplasm per se. Classic histologic features include histiocytes that are S100 protein positive, are CD1a−, and demonstrate emperipolesis. Cutaneous lesions can occur in about 10% of patients, however, RDD limited only to cutaneous involvement is particularly rare.2, 3 Moreover, concomitant cutaneous RDD (CRDD) and bone RDD has rarely been reported in the English-language literature.4, 5 Here, we presented a case of CRDD on the scalp with underlying bony involvement.

A Case of Merkel Cell Carcinoma Treated with Anti-CTLA-4 Antibody (Ipilimumab)

Merkel Cell Carcinoma (MCC) is a rare but aggressive skin cancer. Similar to melanoma, infiltration of CD8+ T cells is associated with an improved prognosis, which provides rationale for immunotherapy in MCC. This manuscript reports the first application of ipilimumab in the treatment of a MCC patient. In this case, combination treatment of a stage IV MCC patient with ipilimumab, radiotherapy, and chemotherapy resulted in stable disease. Unfortunately, the patient passed away from an unrelated cardiac event prior to being able to be fully evaluated for the effects of ipilimumab. Immunotherapy represents a promising treatment option for advanced cancers. Ongoing clinical trials should provide information regarding the efficacy of immunotherapy in otherwise often-lethal metastatic MCC.

SU‐E‐T‐346: Effect of Jaw Position On Dose to Critical Structures in 3‐D Conformal Radiotherapy Treatment of Pancreatic Cancer

Purpose: Three-dimensional conformal therapy remains a valid and widely used modality for pancreatic radiotherapy treatment. It usually meets dose constraints on critical structures. However, careful positioning of collimation jaws can reduce dose to the critical structures. Here we investigate the dosimetric effect of jaw position in MLC-based 3-D conformal treatment planning on critical structures. Methods: We retrospectively selected seven pancreatic cancer patients treated with 3-D conformal radiotherapy. We started with treatment plans (Varian Truebeam LINAC, Eclipse TPS, AAA, 18MV) having both x and y jaws aligned with the farthest extent of the block outline (8mm around PTV). Then we subsequently moved either both x-jaws or all x and y jaws outwards upto 3 cm in 1 cm increments and investigated their effect on average and maximum dose to neighboring critical structures keeping the same coverage to treatment volume. Results: Lateral displacement of both x-jaws by 1cm each increased kidney and spleen mean dose by as much as 1.7% and 1.3% respectively and superior inferior displacement increased liver, right kidney, stomach and spleen dose by as much as 2.1%, 2%, 5.2% and 1.6% respectively. Displacement of all x and y-jaws away by 1cm increased the mean dose to liver, right kidney, left kidney, bowels, cord, stomach and spleen by as much as 4.9%, 5.9%, 2.1%, 2.8%, 7.4%, 10.4% and 4.2% respectively. Percentage increase in mean dose due to 2 and 3cm jaw displacement increased almost linearly with the displaced distance. Changes in maximum dose were much smaller (mostly negligible) than the changes in mean dose. Conclusion: Collimation jaw position affects dose mostly to critical structures adjacent to it. Though treatment plans with MLCs conforming the block margin usually meet dose constraints to critical structures, keeping jaws all the way in, to the edge of the block reduces dose to the critical structures during radiation treatment.

Dosimetric effect on pediatric conformal treatment plans using dynamic jaw with Tomotherapy HDA

It is important to minimize the radiation dose delivered to healthy tissues in pediatric cancer treatment because of the risk of secondary malignancies. Tomotherapy HDA provides a dynamic jaw (DJ) delivery mode that creates a sharper penumbra at the craniocaudal ends of a target in addition to a fixed jaw (FJ) delivery mode. The purpose of this study was to evaluate its dosimetric effect on the pediatric cancer cases. We included 6 pediatric cases in this study. The dose profiles and plan statistics—target dose conformity, uniformity, organ-at-risk (OAR) mean dose, beam-on time, and integral dose—were compared for each case. Consequently, the target dose coverage and uniformity were similar for different jaw settings. The OAR dose sparing depended on its relative location to the target and disease sites. For example, in the head and neck cancer cases, the brain stem dose using DJ 2.5 was reduced by more than two-fold (2.4 Gy vs. 6.3 Gy) than that obtained with FJ 2.5. The integral dose with DJ 2.5 decreased by more than 9% compared with that with FJ 2.5. Thus, using dynamic jaw in pediatric cases could be critical to reduce a probability of a secondary malignancy.

SU-E-T-263: Point Dose Variation Using a Single Ir-192 HDR Brachytherapy Plan for Two Treatments with a Single Tandem-Ovoid Insertion for Cervical Cancer

PURPOSE To evaluate the point dose variations between Ir-192 HDR treatments on two consecutive days using a single tandem-ovoid insertion without replanning in cervical cancer patients. METHODS This study includes eleven cervical cancer patients undergoing HDR brachytherapy with a prescribed dose of 28 Gy in 4 fractions. Each patient had two tandemovoid insertions one week apart. Each insertion was treated on consecutive days with rescanning and replanning prior to each treatment. To study the effect of no replanning for day 2 treatments, the day 1 plan dwell position and dwell time with decay were applied to the day 2 CT dataset. The point dose variations on the prescription point H (defined according to American Brachytherapy Society), and normal tissue doses at point B, bladder, rectum and vaginal mucosa (based on ICRU Report 38) were obtained. RESULTS Without replanning, the mean point H dose variation was 4.6 ± 10.7% on the left; 2.3 ± 2.9% on the right. The mean B point variation was 3.8 ± 4.9% on the left; 3.6 ± 4.7% on the right. The variation in the left vaginal mucosal point was 12.2 ± 10.7%; 9.5 ± 12.5% on the right; the bladder point 5.5 ± 7.4%; and the rectal point 7.9 ± 9.1%. CONCLUSION Without replanning, there are variations both in the prescription point and the normal tissue point doses. The latter can vary as much as 10% or more. This is likely due to the steep dose gradient from brachytherapy compounded by shifts in the positions of the applicator in relationship to the patients anatomy. Imaging prior to each treatment and replanning ensure effective and safe brachytherapy are recommended.