Stereotactic Body Radiation Therapy for Spinal Metastases in the Postoperative Setting: A Secondary Analysis of Mature Phase 1-2 Trials

PURPOSE

To evaluate the outcomes in patients treated on prospective phase 1-2 protocols with postoperative stereotactic body radiation therapy (SBRT) and identify the associated prognostic variables.

METHODS AND MATERIALS

Sixty-six patients with 69 tumors were treated with SBRT on prospective phase 1-2 studies for spinal metastases between 2002 and 2010. All patients underwent SBRT after spine surgery, which included laminectomy, vertebrectomy, or a combination of these techniques. Renal cell carcinoma was the most common histology represented (n=35, 53%) followed by sarcomas (n=13, 20%). Thirty-one patients (47%) were treated with prior conventional radiation to the spine (median dose 30 Gy). Patients were followed up with spinal magnetic resonance imaging (MRI) studies to determine the treated tumor control (TC). Pain and other symptom data were collected prospectively to determine treatment response and toxicity.

RESULTS

The median follow-up time was 30 months (range, 1-145 months) for all patients and 75 months for living patients (range, 6-145 months). The actuarial 1-year rate of TC was 85%, adjacent vertebral body control was 85%, and overall survival (OS) was 74% (median 29 months). On multivariate competing-risks analysis, sarcoma histology (subhazard ratio [SHR] = 2.38, 95% confidence interval [CI] 1.05-5.6, P=.04) and larger preoperative tumor volumes (SHR=1.01, 95% CI 1.0-1.01, P=.006) were significantly associated with worse TC. Karnofsky performance status was the only significant predictor for OS on multivariate analysis. There were no differences in TC between patients treated with different surgical techniques or different preoperative or postoperative Bilsky grades. There were no grade 3 or higher neurologic toxicities.

CONCLUSION

This study represents a large series of prospective data available on patients treated with SBRT in the postoperative setting. The combination of surgery with SBRT can offer patients with metastatic disease to the spine the chance of durable tumor control with minimal toxicity.

Prospective validation of treatment accuracy using implanted fiducial markers for spinal stereotactic body radiation therapy

In order to accurately assess positioning errors in spinal SBRT, many institutions employ bony-fusion based imaging techniques, such as the ExacTrac™ (Brain Lab) system, in conjunction with 3D verification (performed via CT-on-rails in our practice). We hypothesized that the use of implanted gold fiducial markers could improve the accuracy of patient positioning over bony fusion alone. We addressed this question prospectively, enrolling patients on an IRB-approved protocol. Gold seeds were implanted in the vertebral pedicles flanking the target level. At treatment, setup error was calculated using two methods-standard kV image fusion, and geometric fiducial-based projection, with independent CT-on-rails verification. Analyses of residual set-up error showed that fiducial-based setup agreed with fusion-based determination, but did not significantly reduce error. Offline 6D fusion of the treatment and planning CT illustrated residual rotational error using standard or fiducial based setup. We conclude that the ExacTrac and CT-on-rails platform yields highly accurate results for spinal SBRT setup, with reduced residual error than previously reported. While the addition of fiducials did not further reduce error, the bony fusion approach is now prospectively validated in comparison to implanted fiducials. Both bony fusion and fiducial marker methods are associated with residual rotational error, thus 3D verification remains an important component of spinal SBRT treatment.

Factors affecting survival in 37 consecutive patients undergoing de novo stereotactic radiosurgery for contiguous sites of vertebral body metastasis from renal cell carcinoma

OBJECT

Palliative resection of renal cell carcinoma (RCC) spinal metastasis is indicated in cases of neurological compromise or mechanical instability, whereas conventional external beam radiotherapy (EBRT) is commonly used for pain control. Recently, spinal stereotactic radiosurgery (SRS) has emerged as a safe alternative, delivering higher therapeutic doses of radiation to spinal metastases. To better understand factors affecting survival in patients undergoing spinal SRS for metastatic RCC, the authors performed a retrospective analysis of a consecutive series of cases at a tertiary cancer center.

METHODS

Patients harboring contiguous sites of vertebral body involvement from metastatic RCC who received upfront spinal SRS treatment at The University of Texas MD Anderson Cancer Center between 2005 and 2012 were identified. Demographic data, pain scores, radiographic data, overall survival, complications, status of systemic disease, neurological and functional status, and time between primary diagnosis and diagnosis of metastasis (systemic and spinal) were analyzed to determine their influence on survival.

RESULTS

Thirty-seven patients receiving treatment for 40 distinct, contiguous sites of disease were included. The median overall survival after spinal SRS was 16.3 months (range 7.4–25.3 months). Univariate analysis revealed several factors significantly associated with improved overall survival. Local progression after spinal SRS was associated with worse overall survival compared with sustained local control (HR 3.4, 95% CI 1.6–7.4, p = 0.002). Median survival in patients with a Karnofsky Performance Scale (KPS) score ≥ 70 was longer than in patients with a KPS score < 70 (HR 4.7, 95% CI 2.1–10.7, p < 0.001). Patients with neurological deficits at the time of spinal SRS had a shorter median survival than those without (HR 4.2, 95% CI 1.4–12.0, p = 0.008). Individuals with nonprogressive systemic disease at the time of spinal SRS had a longer median survival than those with systemic progression at the time of treatment (HR 8.3, 95% CI 3.3–20.7, p < 0.001). Median survival in patients experiencing any metastasis < 12 months after primary RCC diagnosis was shorter than in patients experiencing any metastasis > 12 months after primary diagnosis, a difference that approached but did not attain significance (HR 1.9, 95% CI 0.90–4.1, p = 0.09). On multivariate analysis, local progression of disease after spinal SRS, metastasis < 12 months after primary, KPS score ≤ 70, and progression of systemic disease at time of spinal SRS all remained significant factors influencing survival (respectively, HR 3.7, p = 0.002; HR 2.6, p = 0.026; HR 4.0, p = 0.002; and HR 13.2, p < 0.001).

CONCLUSIONS

We identified several factors associated with survival after spinal SRS for RCC metastases, including local progression, time between first metastasis and primary RCC diagnosis, KPS score, presence of neurological deficits, and progressive metastatic disease. These factors should be taken into consideration when considering a patient for spinal SRS for RCC metastases.

Correlation of BRAF and NRAS mutation status with tumor characteristics and treatment outcomes in melanoma patients with brain metastasis

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Background: The management of melanoma has evolved rapidly with the identification of activating mutations in the majority of patients (pts). We reviewed characteristics and outcomes of molecularly characterized melanoma pts with brain metastasis (BM) to help design and interpret future clinical trials. Methods: We reviewed clinical and pathologic features of melanoma pts with known BRAF and NRAS mutation status and BM. Pt demographics, intra- (IC) and extra-cranial (EC) tumor characteristics, and IC/EC disease treatments were correlated to BM treatment outcomes (local and distant brain control [LC, DC]) and overall survival (OS). Univariate and multivariate analyses were performed to identify significant associations between mutation status and outcome. Results: We identified 296 pts with melanoma BM and known BRAF/NRAS mutation status diagnosed from 2005 to 2011. Mutation prevalence was BRAF 57%, NRAS 17%, and wild-type for both genes (WT) 26%. The initial treatments given for BM were surgery/radiosurgery (SRS) 60%, surgery/SRS + whole brain radiation (WBRT) 7%, WBRT alone 19%, systemic therapy alone 9%, and no treatment 5%. Mutation status was not significantly associated with sex, performance status, EC disease status, number of brain lesions, or BM treatment. Pts with mutations were younger (p<0.0001) and more likely to have symptomatic BM (p=0.0003) than WT pts. In univariate analysis, BM treatment strategy (p<0.001) and mutation status predicted for poor LC, with 6 month LC rates of 70% for any mutation and 88% for WT (HR=1.86, p=0.048). Compared to systemic agents alone, use of radiation (SRS or WBRT) improved LC for pts with a mutation (HR 0.23, p=0.0006). Subsequent multivariate analysis identified mutation status and radiation treatment as independent predictors of LC (HR 2.5 and 0.25, respectively). Mutation status did not predict for DC or OS. Conclusions: The presence of BRAF and NRAS mutations predicts worse LC following conventional treatments for melanoma BM. Radiation may improve LC in pts with a mutation. This data suggest a role for combining radiation with targeted therapies in melanoma pts with activating BRAF or NRAS mutations in the treatment of BM.

Failure patterns in patients with esophageal cancer treated with definitive chemoradiation

BACKGROUND

Local failure after definitive chemoradiation therapy for unresectable esophageal cancer remains problematic. Little is known about the failure pattern based on modern-day radiation treatment volumes. We hypothesized that most local failures would be within the gross tumor volume (GTV), where the bulk of the tumor burden resides.

METHODS

We reviewed treatment volumes for 239 patients who underwent definitive chemoradiation therapy and compared this information with failure patterns on follow-up positron emission tomography (PET). Failures were categorized as within the GTV, the larger clinical target volume (CTV, which encompasses microscopic disease), or the still larger planning target volume (PTV, which encompasses setup variability) or outside the radiation field.

RESULTS

At a median follow-up time of 52.6 months (95% confidence interval, 46.1-56.7 months), 119 patients (50%) had experienced local failure, 114 (48%) had distant failure, and 74 (31%) had no evidence of failure. Of all local failures, 107 (90%) were within the GTV, 27 (23%) were within the CTV, and 14 (12%) were within in the PTV. On multivariate analysis, GTV failure was associated with tumor status (T3/T4 vs T1/T2; odds ratio, 6.35; P = .002), change in standardized uptake value on PET before and after treatment (decrease >52%: odds ratio, 0.368; P = .003), and tumor size (>8 cm, 4.08; P = .009).

CONCLUSIONS

Most local failures after definitive chemoradiation for unresectable esophageal cancer occur in the GTV. Future therapeutic strategies should focus on enhancing local control.

Discovering functional modules by identifying recurrent and mutually exclusive mutational patterns in tumors

Background

Assays of multiple tumor samples frequently reveal recurrent genomic aberrations, including point mutations and copy-number alterations, that affect individual genes. Analyses that extend beyond single genes are often restricted to examining pathways, interactions and functional modules that are already known.

Methods

We present a method that identifies functional modules without any information other than patterns of recurrent and mutually exclusive aberrations (RME patterns) that arise due to positive selection for key cancer phenotypes. Our algorithm efficiently constructs and searches networks of potential interactions and identifies significant modules (RME modules) by using the algorithmic significance test.

Results

We apply the method to the TCGA collection of 145 glioblastoma samples, resulting in extension of known pathways and discovery of new functional modules. The method predicts a role for EP300 that was previously unknown in glioblastoma. We demonstrate the clinical relevance of these results by validating that expression of EP300 is prognostic, predicting survival independent of age at diagnosis and tumor grade.

Conclusions

We have developed a sensitive, simple, and fast method for automatically detecting functional modules in tumors based solely on patterns of recurrent genomic aberration. Due to its ability to analyze very large amounts of diverse data, we expect it to be increasingly useful when applied to the many tumor panels scheduled to be assayed in the near future.

Transcriptional recapitulation and subversion of embryonic colon development by mouse colon tumor models and human colon cancer

Colon tumors from four independent mouse models and 100 human colorectal cancers all exhibited striking recapitulation of embryonic colon gene expression from embryonic days 13.5-18.5.

Background

The expression of carcino-embryonic antigen by colorectal cancer is an example of oncogenic activation of embryonic gene expression. Hypothesizing that oncogenesis-recapitulating-ontogenesis may represent a broad programmatic commitment, we compared gene expression patterns of human colorectal cancers (CRCs) and mouse colon tumor models to those of mouse colon development embryonic days 13.5-18.5.

Results

We report here that 39 colon tumors from four independent mouse models and 100 human CRCs encompassing all clinical stages shared a striking recapitulation of embryonic colon gene expression. Compared to normal adult colon, all mouse and human tumors over-expressed a large cluster of genes highly enriched for functional association to the control of cell cycle progression, proliferation, and migration, including those encoding MYC, AKT2, PLK1 and SPARC. Mouse tumors positive for nuclear β-catenin shifted the shared embryonic pattern to that of early development. Human and mouse tumors differed from normal embryonic colon by their loss of expression modules enriched for tumor suppressors (EDNRB, HSPE, KIT and LSP1). Human CRC adenocarcinomas lost an additional suppressor module (IGFBP4, MAP4K1, PDGFRA, STAB1 and WNT4). Many human tumor samples also gained expression of a coordinately regulated module associated with advanced malignancy (ABCC1, FOXO3A, LIF, PIK3R1, PRNP, TNC, TIMP3 and VEGF).

Conclusion

Cross-species, developmental, and multi-model gene expression patterning comparisons provide an integrated and versatile framework for definition of transcriptional programs associated with oncogenesis. This approach also provides a general method for identifying pattern-specific biomarkers and therapeutic targets. This delineation and categorization of developmental and non-developmental activator and suppressor gene modules can thus facilitate the formulation of sophisticated hypotheses to evaluate potential synergistic effects of targeting within- and between-modules for next-generation combinatorial therapeutics and improved mouse models.

Chronic treatment of Ménétrier's disease with Erbitux: clinical efficacy and insight into pathophysiology

BACKGROUND & AIMS

Ménétrier's disease is a rare premalignant hypertrophic gastropathy characterized by large rugal folds, foveolar hyperplasia with glandular atrophy, hypochlorhydria, and hypoalbuminemia. Patients with severe disease often exhibit refractory nausea and vomiting and require gastrectomy. Evidence from both mice and human beings suggests a critical role for epidermal growth factor receptor (EGFR) signaling in the pathogenesis of this disease. We previously reported significant clinical and biochemical improvement of a single patient treated for 1 month with Erbitux, a monoclonal antibody that blocks ligand binding to EGFR.

METHODS/RESULTS

We describe 2 patients who were given longer-term treatment with Erbitux as an alternative to gastrectomy. The first patient presented with nausea, hypoalbuminemia, and peripheral edema that required total parenteral nutrition (TPN) and infusions of albumin. On institution of Erbitux, there was rapid improvement in nausea and vomiting and stabilization of serum albumin with discontinuation of TPN and albumin infusions. Serum albumin remained stable during a 1-year course of Erbitux without supplemental protein. Application before and after Erbitux of the radiopaque dye ruthenium red to biopsies of the gastric oxyntic gland mucosa demonstrated prompt and persistent closure of tight junctions by electron microscopy. The second patient presented with chronic gastric bleeding that required bimonthly blood transfusions. During a 4-month course of Erbitux, his hematocrit stabilized, and transfusion requirements were eliminated.

CONCLUSIONS

The present report demonstrates the efficacy of prolonged Erbitux therapy in patients with different presentations of severe Ménétrier's disease and also provides insight into the pathophysiology of the protein-losing gastropathy.

Evidence for repatterning of the gastric fundic epithelium associated with Ménétrier's disease and TGFalpha overexpression

BACKGROUND & AIMS

Increase of intramucosal transforming growth factor alpha (TGFalpha) levels in the gastric fundus leads to oxyntic atrophy and massive foveolar hyperplasia in both metallothionein (MT)-TGFalpha mice and patients with Ménétrier's disease. We have evaluated the hypothesis that increased levels of TGFalpha in the fundus induces an antral pattern of cell differentiation in fundic glands by studying Pdx1, a transcription factor whose expression normally is confined to the gastric antrum.

METHODS

Induction of Pdx1 expression was evaluated in Pdx1(lacZ/+)/MT-TGFalpha bigenic mice treated with zinc. The distribution of Pdx1 in MT-TGFalpha mice and Ménétrier's disease patients was evaluated with anti-Pdx1 antibodies. Transcript levels were evaluated by quantitative polymerase chain reaction in mouse and human tissues and AGS cells.

RESULTS

In Pdx1(lacZ/+) mice, Pdx1 was expressed in antral mucosal cells including gastrin cells and TFF2-expressing deep glandular mucous cells. Zinc treatment for 2 to 8 weeks in Pdx1(lacZ/+)/MT-TGFalpha transgenic mice resulted in expression of Pdx1 throughout the fundus. No ectopic fundic Pdx1 expression was observed in either H. felis-infected or DMP777-treated mice. In MT-TGFalpha mice, 8 weeks of zinc treatment elicited nuclear Pdx1 staining throughout the fundic mucosa. TGFalpha treatment in AGS cells led to increases in Pdx1 and gastrin messenger RNA expression. Fundic sections from Ménétrier's disease patients showed nuclear Pdx1 staining throughout the fundic glands. Treatment of a Ménétrier's disease patient with an anti-epidermal growth factor receptor monoclonal antibody reduced fundic expression of both Pdx1 and gastrin.

CONCLUSIONS

Overexpression of TGFalpha in MT-TGFalpha mice and Ménétrier's disease patients elicits ectopic expression in the fundus of Pdx1, consistent with the phenotype of antralization.

Gene expression profile analysis of mouse colon embryonic development

During late embryogenesis, the mouse colon develops from a pseudostratified, undifferentiated endoderm to a single-layered columnar epithelium with accompanying mesenchymal maturation. To identify regulatory genetic programs underlying these morphological changes, we profiled gene expression of the developing mouse colon by microarray from embryonic day (E)13.5 to E18.5. Unbiased cluster analysis of 13,484 cDNA elements revealed two distinct groups of genes whose expression changes reflect the dynamic morphological events of the epithelium and mesenchyme during this period. Additional analyses revealed two subsets of genes whose expression is either upregulated or downregulated over the same developmental period. Of those genes whose expression increases from E13.5 to E18.5 (n = 158), known functions include acquisition and/or maintenance of colonic differentiation. Genes whose transcription is downregulated over this period (n = 49) have demonstrated roles in nuclear organization, transcriptional regulation, and cell proliferation. These results provide the basis for a molecular portrait of colonic development during late embryogenesis and should be a valuable resource for investigators interested in colonic development and neoplasia, as well as comparative organogenesis.

Multiple joint and skeletal patterning defects caused by single and double mutations in the mouse Gdf6 and Gdf5 genes

Growth/differentiation factors 5, 6, and 7 (GDF5/6/7) represent a distinct subgroup within the bone morphogenetic protein (BMP) family of secreted signaling molecules. Previous studies have shown that the Gdf5 gene is expressed in transverse stripes across developing skeletal elements and is one of the earliest known markers of joint formation during embryonic development. Although null mutations in this gene disrupt formation of some bones and joints in the skeleton, many sites are unaffected. Here, we show that the closely related family members Gdf6 and Gdf7 are expressed in different subsets of developing joints. Inactivation of the Gdf6 gene causes defects in joint, ligament, and cartilage formation at sites distinct from those seen in Gdf5 mutants, including the wrist and ankle, the middle ear, and the coronal suture between bones in the skull. Mice lacking both Gdf5 and Gdf6 show additional defects, including severe reduction or loss of some skeletal elements in the limb, additional fusions between skeletal structures, scoliosis, and altered cartilage in the intervertebral joints of the spinal column. These results show that members of the GDF5/6/7 subgroup are required for normal formation of bones and joints in the limbs, skull, and axial skeleton. The diverse effects on joint development and the different types of joints affected in the mutants suggest that members of the GDF family play a key role in establishing boundaries between many different skeletal elements during normal development. Some of the skeletal defects seen in single or double mutant mice resemble defects seen in human skeletal diseases, which suggests that these genes may be candidates that underlie some forms of carpal/tarsal coalition, conductive deafness, scoliosis, and craniosynostosis.

Importance of epidermal growth factor receptor signaling in establishment of adenomas and maintenance of carcinomas during intestinal tumorigenesis

We used the hypomorphic Egfr(wa2) allele to genetically examine the impact of impaired epidermal growth factor receptor (Egfr) signaling on the Apc(Min) mouse model of familial adenomatous polyposis. Transfer of the Apc(Min) allele onto a homozygous Egfr(wa2) background results in a 90% reduction in intestinal polyp number relative to Apc(Min) mice carrying a wild-type Egfr allele. This Egfr effect is potentially synergistic with the actions of the modifier-of-min (Mom1) locus. Surprisingly, the size, expansion, and pathological progression of the polyps appear Egfr-independent. Histological examination of the ilea of younger animals revealed no differences in the number of microadenomas, the presumptive precursor lesions to gross intestinal polyps. Pharmacological inhibition with EKI-785, an Egfr tyrosine kinase inhibitor, produced similar results in the Apc(Min) model. These data suggest that normal Egfr activity is required for establishment of intestinal tumors in the Apc(Min) model between initiation and subsequent expansion of initiated tumors. The role of Egfr signaling during later stages of tumorigenesis was examined by using nude mice xenografts of two human colorectal cancer cell lines. Treatment with EKI-785 produced a dose-dependent reduction in tumor growth, suggesting that Egfr inhibitors may be useful for advanced colorectal cancer treatment.

The silver gene of Drosophila melanogaster encodes multiple carboxypeptidases similar to mammalian prohormone-processing enzymes

The silver (svr) gene of Drosophila melanogaster is required for viability, and severe mutant alleles result in death prior to eclosion. Adult flies homozygous or hemizygous for weaker alleles display several visible phenotypes, including cuticular structures that are pale and silvery in color due to reduced melanization. We have identified and cloned the DNA encoding the svr gene and determined the sequence of several partially overlapping cDNAs derived from svr mRNAs. The predicted amino acid sequence of the polypeptides encoded by these cDNAs indicates that the silver proteins are members of the family of preprotein-processing carboxypeptidases that includes the human carboxypeptidases E, M, and N. One class of svr mRNAs is alternatively spliced to encode at least two polyproteins, each of which is composed of two carboxypeptidase domains.