Voxel-Level Dosimetry for Combined Iodine 131 Radiopharmaceutical Therapy and External Beam Radiation Therapy Treatment Paradigms for Head and Neck Cancer.

PURPOSE: Targeted radiopharmaceutical therapy (RPT) in combination with external beam radiation therapy (EBRT) shows promise as a method to increase tumor control and mitigate potential high-grade toxicities associated with re-treatment for patients with recurrent head and neck cancer. This work establishes a patient-specific dosimetry framework that combines Monte Carlo-based dosimetry from the 2 radiation modalities at the voxel level using deformable image registration (DIR) and radiobiological constructs for patients enrolled in a phase 1 clinical trial combining EBRT and RPT. METHODS AND MATERIALS: Serial single-photon emission computed tomography (SPECT)/computed tomography (CT) patient scans were performed at approximately 24, 48, 72, and 168 hours postinjection of 577.2 MBq/m2 (15.6 mCi/m2) CLR 131, an iodine 131-containing RPT agent. Using RayStation, clinical EBRT treatment plans were created with a treatment planning CT (TPCT). SPECT/CT images were deformably registered to the TPCT using the Elastix DIR module in 3D Slicer software and assessed by measuring mean activity concentrations and absorbed doses. Monte Carlo EBRT dosimetry was computed using EGSnrc. RPT dosimetry was conducted using RAPID, a GEANT4-based RPT dosimetry platform. Radiobiological metrics (biologically effective dose and equivalent dose in 2-Gy fractions) were used to combine the 2 radiation modalities. RESULTS: The DIR method provided good agreement for the activity concentrations and calculated absorbed dose in the tumor volumes for the SPECT/CT and TPCT images, with a maximum mean absorbed dose difference of -11.2%. Based on the RPT absorbed dose calculations, 2 to 4 EBRT fractions were removed from patient EBRT treatments. For the combined treatment, the absorbed dose to target volumes ranged from 57.14 to 75.02 Gy. When partial volume corrections were included, the mean equivalent dose in 2-Gy fractions to the planning target volume from EBRT + RPT differed -3.11% to 1.40% compared with EBRT alone. CONCLUSIONS: This work demonstrates the clinical feasibility of performing combined EBRT + RPT dosimetry on TPCT scans. Dosimetry guides treatment decisions for EBRT, and this work provides a bridge for the same paradigm to be implemented within the rapidly emerging clinical RPT space.

Validation of Monte Carlo 131 I radiopharmaceutical dosimetry workflow using a 3D-printed anthropomorphic head and neck phantom.

PURPOSE: Approximately 50% of head and neck cancer (HNC) patients will experience loco-regional disease recurrence following initial courses of therapy. Retreatment with external beam radiotherapy (EBRT) is technically challenging and may be associated with a significant risk of irreversible damage to normal tissues. Radiopharmaceutical therapy (RPT) is a potential method to treat recurrent HNC in conjunction with EBRT. Phantoms are used to calibrate and add quantification to nuclear medicine images, and anthropomorphic phantoms can account for both the geometrical and material composition of the head and neck. In this study, we present the creation of an anthropomorphic, head and neck, nuclear medicine phantom, and its characterization for the validation of a Monte Carlo, SPECT image-based, 131 I RPT dosimetry workflow. METHODS: 3D-printing techniques were used to create the anthropomorphic phantom from a patient CT dataset. Three 131 I SPECT/CT imaging studies were performed using a homogeneous, Jaszczak, and an anthropomorphic phantom to quantify the SPECT images using a GE Optima NM/CT 640 with a high energy general purpose collimator. The impact of collimator detector response (CDR) modeling and volume-based partial volume corrections (PVCs) upon the absorbed dose was calculated using an image-based, Geant4 Monte Carlo RPT dosimetry workflow and compared against a ground truth scenario. Finally, uncertainties were quantified in accordance with recent EANM guidelines. RESULTS: The 3D-printed anthropomorphic phantom was an accurate re-creation of patient anatomy including bone. The extrapolated Jaszczak recovery coefficients were greater than that of the 3D-printed insert (∼22.8 ml) for both the CDR and non-CDR cases (with CDR: 0.536 vs. 0.493, non-CDR: 0.445 vs. 0.426, respectively). Utilizing Jaszczak phantom PVCs, the absorbed dose was underpredicted by 0.7% and 4.9% without and with CDR, respectively. Utilizing anthropomorphic phantom recovery coefficient overpredicted the absorbed dose by 3% both with and without CDR. All dosimetry scenarios that incorporated PVC were within the calculated uncertainty of the activity. The uncertainties in the cumulative activity ranged from 23.6% to 106.4% for Jaszczak spheres ranging in volume from 0.5 to 16 ml. CONCLUSION: The accuracy of Monte Carlo-based dosimetry for 131 I RPT in HNC was validated with an anthropomorphic phantom. In this study, it was found that Jaszczak-based PVCs were sufficient. Future applications of the phantom could involve 3D printing and characterizing patient-specific volumes for more personalized RPT dosimetry estimates.

Radiation Dose Escalation in Esophageal Cancer Revisited: A Contemporary Analysis of the National Cancer Data Base, 2004 to 2012.

PURPOSE: To evaluate the effect of radiation dose escalation on overall survival (OS) for patients with nonmetastatic esophageal cancer treated with concurrent radiation and chemotherapy. METHODS AND MATERIALS: Patients diagnosed with stage I to III esophageal cancer treated from 2004 to 2012 were identified from the National Cancer Data Base. Patients who received concurrent radiation and chemotherapy with radiation doses of ≥50 Gy and did not undergo surgery were included. OS was compared using Cox proportional hazards regression and propensity score matching. RESULTS: A total of 6854 patients were included; 3821 (55.7%) received 50 to 50.4 Gy and 3033 (44.3%) received doses >50.4 Gy. Univariate analysis revealed no significant difference in OS between patients receiving 50 to 50.4 Gy and those receiving >50.4 Gy (P=.53). The dose analysis, binned as 50 to 50.4, 51 to 54, 55 to 60, and >60 Gy, revealed no appreciable difference in OS within any group compared with 50 to 50.4 Gy. Subgroup analyses investigating the effect of dose escalation by histologic type and in the setting of intensity modulated radiation therapy also failed to reveal a benefit. Propensity score matching confirmed the absence of a statistically significant difference in OS among the dose levels. The factors associated with improved OS on multivariable analysis included female sex, lower Charlson-Deyo comorbidity score, private insurance, cervical/upper esophagus location, squamous cell histologic type, lower T stage, and node-negative status (P<.01 for all analyses). CONCLUSIONS: In this large national cohort, dose escalation >50.4 Gy did not result in improved OS among patients with stage I to III esophageal cancer treated with definitive concurrent radiation and chemotherapy. These data suggest that despite advanced contemporary treatment techniques, OS for patients with esophageal cancer remains unaltered by escalation of radiation dose >50.4 Gy, consistent with the results of the INT-0123 trial. Furthermore, these data highlight that many radiation oncologists have not embraced the concept that dose escalation does not improve OS. Although local control, not investigated in the present study, might benefit from dose escalation, novel therapies are needed to improve the OS of patients with esophageal cancer.

Association of human papillomavirus and p16 status with mucositis and dysphagia for head and neck cancer patients treated with radiotherapy with or without cetuximab: Assessment from a phase 3 registration trial.

BACKGROUND: Mucositis and dysphagia are common adverse effects of radiotherapy (RT) treatment of locally advanced squamous cell cancer of the head and neck (LA-SCCHN). Chemotherapy added to RT increases survival rates but causes worse mucositis and dysphagia. The aim of this analysis was to assess the impact of p16 status on mucositis, dysphagia, and feeding tube use in LA-SCCHN among patients treated with RT±cetuximab in the phase 3 IMCL-9815 trial. METHODS: Patients received RT plus weekly cetuximab or RT alone. Subgroup analyses were conducted on patients with p16-positive (n=75) or p16-negative (n=106) oropharyngeal cancer (OPC), as determined by immunohistochemical analysis. The onset and duration of mucositis and dysphagia by treatment arm and p16 status were displayed using Kaplan-Meier curves and the log-rank test. P values for the incidence of mucositis and dysphagia were calculated using the Fisher exact test. Feeding tube use was assessed as the percent of patients reporting use. RESULTS: The baseline characteristics of patients treated with RT±cetuximab were similar in both the p16-positive and p16-negative OPC subgroups. Patients within the p16-positive OPC subgroup had higher Karnofsky scores and were more likely to have stage T1-T3 cancer and be from the United States. Regardless of p16 status, there was no difference in the onset or duration of grade 3/4 mucositis or dysphagia in patients receiving RT plus cetuximab compared with those receiving RT alone. In the overall population, and the p16-positive and p16-negative OPC subpopulations, feeding tube use was not different for patients receiving RT plus cetuximab compared with RT alone. CONCLUSION: Regardless of p16 status, the addition of cetuximab to RT did not alter the incidence, time to onset, severity, or duration of mucositis and dysphagia and did not impact the frequency of feeding tube use.

Assessing p16 Status of Oropharyngeal Squamous Cell Carcinoma by Combined Assessment of the Number of Cells Stained and the Confluence of p16 Staining: A Validation by Clinical Outcomes.

Human papillomavirus-related oropharyngeal squamous cell carcinoma (OPSCC) has favorable prognosis relative to other head and neck squamous cell carcinomas. Criteria for predicting human papillomavirus status based upon p16 staining, including difficult cases with partial staining patterns, have been developed; however, clinical validation of these criteria and the clinical significance of partial p16 staining have not been reported. Eighty-one archival OPSCC cases were initially stained for p16 by immunohistochemistry with clone G175-405. The percentage of p16 cells and percentage of confluence of p16 cells were categorized as 25%, 26% to 75%, or >75%. Of all cases, 16 (20%) had partial p16 expression, with 26% to 75% p16 cells. Applying previously developed criteria of >75% p16 cells or >50% positive cells with >25% confluence, 48 (59%) patients were categorized p16 and demonstrated expected clinical characteristics and superior disease-free survival and overall survival (P<0.001) compared with p16 patients. By themselves, the partial staining patients had intermediate outcomes; however, separating the partial staining cases by degree of confluence showed that those with >75% confluence had superior disease-free survival (P=0.042). When the 16 original partial staining cases were re-stained with the alternative anti-p16 E6H4 clone, p16 status remained concordant for all cases, but only 3 of the 16 were interpreted as demonstrating partial staining. This report shows that the prevalence of partial p16 staining varies with the antibody utilized and clinically validates the application of a graded evaluation of both the number as well as confluence of positive cells for risk stratification of patients with OPSCC.

Therapeutic combination of radiolabeled CLR1404 with external beam radiation in head and neck cancer model systems.

BACKGROUND AND PURPOSE: CLR1404 is a phospholipid ether that exhibits selective uptake and retention in malignant tissues. Radiolabeled CLR1404 enables tumor-specific positron-emission tomography (PET) imaging ((124)I) and targeted delivery of ionizing radiation ((131)I). Here we describe the first preclinical studies of this diapeutic molecule in head and neck cancer (HNC) models. MATERIAL AND METHODS: Tumor-selective distribution of (124)I-CLR1404 and therapeutic efficacy of (131)I-CLR1404 were tested in HNC cell lines and patient-derived xenograft tumor models. Monte Carlo dose calculations and (124)I-CLR1404 PET/CT imaging were used to examine (131)I-CLR1404 dosimetry in preclinical HNC tumor models. RESULTS: HNC tumor xenograft studies including patient-derived xenografts demonstrate tumor-selective uptake and retention of (124)I-CLR1404 resulting in a model of highly conformal dose distribution for (131)I-CLR1404. We observe dose-dependent response to (131)I-CLR1404 with respect to HNC tumor xenograft growth inhibition and this effect is maintained together with external beam radiation. CONCLUSIONS: We confirm the utility of CLR1404 for tumor imaging and treatment of HNC. This promising agent warrants further investigation in a developing phase I trial combining (131)I-CLR1404 with reduced-dose external beam radiation in patients with loco-regionally recurrent HNC.

Xenograft assessment of predictive biomarkers for standard head and neck cancer therapies.

Head and neck squamous cell carcinoma (HNSCC) remains a challenging cancer to treat with overall 5-year survival on the order of 50-60%. Therefore, predictive biomarkers for this disease would be valuable to provide more effective and individualized therapeutic approaches for these patients. While prognostic biomarkers such as p16 expression correlate with outcome; to date, no predictive biomarkers have been clinically validated for HNSCC. We generated xenografts in immunocompromised mice from six established HNSCC cell lines and evaluated response to cisplatin, cetuximab, and radiation. Tissue microarrays were constructed from pre- and posttreatment tumor samples derived from each xenograft experiment. Quantitative immunohistochemistry was performed using a semiautomated imaging and analysis platform to determine the relative expression of five potential predictive biomarkers: epidermal growth factor receptor (EGFR), phospho-EGFR, phospho-Akt, phospho-ERK, and excision repair cross-complementation group 1 (ERCC1). Biomarker levels were compared between xenografts that were sensitive versus resistant to a specific therapy utilizing a two-sample t-test with equal standard deviations. Indeed the xenografts displayed heterogeneous responses to each treatment, and we linked a number of baseline biomarker levels to response. This included low ERCC1 being associated with cisplatin sensitivity, low phospho-Akt correlated with cetuximab sensitivity, and high total EGFR was related to radiation resistance. Overall, we developed a systematic approach to identifying predictive biomarkers and demonstrated several connections between biomarker levels and treatment response. Despite these promising initial results, this work requires additional preclinical validation, likely involving the use of patient-derived xenografts, prior to moving into the clinical realm for confirmation among patients with HNSCC.

A comprehensive assessment by tumor site of patient setup using daily MVCT imaging from more than 3,800 helical tomotherapy treatments.

PURPOSE: To assess patient setup corrections based on daily megavoltage CT (MVCT) imaging for four anatomic treatment sites treated on tomotherapy. METHOD AND MATERIALS: Translational and rotational setup corrections, based on registration of daily MVCT to planning CT images, were analyzed for 1,179 brain and head and neck (H&N), 1,414 lung, and 1,274 prostate treatment fractions. Frequencies of three-dimensional vector lengths, overall distributions of setup corrections, and patient-specific distributions of random and systematic setup errors were analyzed. RESULTS: Brain and H&N had lower magnitude positioning corrections and smaller variations in translational setup errors but were comparable in roll rotations. Three-dimensional vector translational shifts of larger magnitudes occurred more frequently for lung and prostate than for brain and H&N treatments, yet this was not observed for roll rotations. The global systematic error for prostate was 4.7 mm in the vertical direction, most likely due to couch sag caused by large couch extension distances. Variations in systematic errors and magnitudes of random translational errors ranged from 1.6 to 2.6 mm for brain and H&N and 3.2 to 7.2 mm for lung and prostate, whereas roll rotational errors ranged from 0.8 degrees to 1.2 degrees for brain and H&N and 0.5 degrees to 1.0 degrees for lung and prostate. CONCLUSIONS: Differences in setup were observed between brain, H&N, lung, and prostate treatments. Patient setup can be improved if daily imaging is performed. This analysis can assess the utilization of daily image guidance and allows for further investigation into improved anatomic site-specific and patient-specific treatments.

Strategic plans to promote head and neck cancer translational research within the radiation therapy oncology group: a report from the translational research program.

Head and neck cancer is the fifth most common cancer in the United States, with an overall survival rate of approximately 40-50%. In an effort to improve patient outcomes, research efforts designed to maximize benefit and reduce toxicities of therapy are in progress. Basic research in cancer biology has accelerated this endeavor and provided preclinical data and technology to support clinically relevant advances in early detection, prognostic and predictive biomarkers. Recent completion of the Human Genome Project has promoted the rapid development of novel "omics" technologies that allow more broad based study from a systems biology perspective. However, clinically relevant application of resultant gene signatures to clinical trials within cooperative groups has advanced slowly. In light of the large numbers of variables intrinsic to biomarker studies, validation of preliminary data for clinical implementation presents a significant challenge and may only be realized with large trials that involve significant patient numbers. The Radiation Therapy Oncology Group (RTOG) Head and Neck Cancer Translational Research Program recognizes this problem and brings together three unique features to facilitate this research: (1) availability of large numbers of clinical specimens from homogeneously treated patients through multi-institutional clinical trials; (2) a team of physicians, scientists, and staff focused on patient-oriented head-and-neck cancer research with the common goal of improving cancer care; and (3) a funding mechanism through the RTOG Seed Grant Program. In this position paper we outline strategic plans to further promote translational research within the framework of the RTOG.

Cetuximab (Imclone/Merck/Bristol-Myers Squibb).

ImClone, in collaboration with licensees, Merck KGaA and Bristol-Myers Squibb (BMS), are developing cetuximab, a chimeric monoclonal antibody that blocks the epidermal growth factor receptor, for the potential treatment of various cancers, including colorectal, and head and neck tumors [179103]. The companies are evaluating the product both as a single agent, and in combination with radiation and a variety of chemotherapeutic agents. By January 2002, phase III trials had been initiated in head and neck cancer, and phase II trials were ongoing for colorectal and other cancers [427710], [437833]. In November 2001, ImClone completed the filing of a rolling BLA with the FDA for cetuximab in combination with irinotecan to treat irinotecan-refractory colorectal cancer. In December 2001, however, the FDA advised ImClone that its BLA was not acceptable for filing. In January 2002, it was reported that resubmission of the BLA was expected within 3 months [434999], and by February 2002, ImClone was expecting to use data from an ongoing phase II study in colorectal cancer patients conducted by Merck KGaA. In March 2002, Merck had anticipated European launch in 2003 [444653]; however, in April 2002, Merck reported that it was delaying its application to the European Agency for the Evaluation of Medicinal Products from the last half of 2002 to the first half of 2003, so that it could primarily include its own colorectal cancer data rather than ImClone's data. European launch was thus expected in 2004 [449226]. In May 2002, Lehman Brothers predicted global peak sales of US $2 billion [454652], while in the same month, Bear Stearns estimated that sales for Merck KGaA would reach 285 million Euros in 2007 [453500].