Investigation of a Novel Decision Support Metric for Head and Neck Adaptive Radiation Therapy Using a Real-Time In Vivo Portal Dosimetry System

In adaptive radiation therapy of head and neck cancer, any significant anatomical changes observed are used to adapt the treatment plan to maintain target coverage without elevating the risk of xerostomia. However, the additional resources required for adaptive radiation therapy pose a challenge for broad-based implementation. It is hypothesized that a change in transit fluence is associated with volumetric change in the vicinity of the target and therefore can be used as a decision support metric for adaptive radiation therapy. This was evaluated by comparing the fluence with volumetric changes in 12 patients. Transit fluence was measured by an in vivo portal dosimetry system. Weekly cone beam computed tomography was used to determine volume change in the rectangular region of interest from condyloid process to C6. The integrated transit fluence through the region of interest on the day of the cone beam computed tomography scan was calculated with the first treatment as the baseline. The correlation between fluence change and volume change was determined. A logistic regression model was also used to associate the 5% region of interest volume reduction replanning trigger point and the fluence change. The model was assessed by a chi-square test. The area under the receiver-operating characteristic curve was also determined. A total of 46 pairs of measurements were obtained. The correlation between fluence and volumetric changes was found to be -0.776 (P value <.001). The negative correlation is attributed to the increase in the photon fluence transport resulting from the volume reduction. The chi-square of the logistic regression was found to be 17.4 (P value <.001). The area under the receiver-operating characteristic curve was found to be 0.88. Results indicate the change in transit fluence, which can be measured without consuming clinical resources or requiring additional time in the treatment room, can be used as a decision support metric for adaptive therapy.

Prognostic implications of YKL-40 overexpression in breast cancer

20115

Background: YKL-40 has been implicated as a connective tissue growth factor and a migratory factor for endothelial cells. Elevated serum levels of YKL-40 have been found to correlate with worse survival in a variety of malignancies including breast cancer. We wished to determine if tumor overexpression of this protein also had prognostic implications in breast cancer. Methods: A prospectively collected database of breast cancer patients treated at the University Hospital of Newark was used for analysis. Immunohistochemical analysis was performed on 115 patients for whom full clinical information and follow up was available. Specimens were categorized as lacking immunoreactivity (0), having focal sparse immunoreactivity (1), or strong more diffuse immunoreactivity (2). Results: YKL-40 expression was noted in 38 patients (33%). Of these, 24 demonstrated strong (2) immunoreactivity (21%). Strong (2) YKL-40 immunoreactivity significantly correlated with larger tumor size (p < .05). Tumors expressing any level of YKL-40 were also significantly more likely to be estrogen and/or progesterone receptor negative (p < .01). No significant correlation was demonstrated between YKL-40 status and nodal stage. At a mean follow up of 2.3 years, disease-free survival was significantly worse in the subset of patients whose tumors overexpressed any level of YKL-40 compared to the non-expressors (p < .01). In multivariate analysis, YKL-40 status was independent of T-stage and N-stage in predicting disease recurrence. Conclusions: Immunoreactivity for YKL-40 was a significant predictor of breast cancer relapse in this subset of patients. This was independent of T or N-stage and suggests that tumor immunohistochemistry for this protein may be a valuable prognostic marker in breast cancer.

No significant financial relationships to disclose.

Cell cycle effects of IL-10 on malignant B-1 cells

IL-10 is overexpressed in human chronic lymphocytic leukemia (CLL), and is an autocrine growth factor involved in the development of malignant B1 clones in NZB mice, a murine model for CLL. Antisense IL-10 oligonucleotide treatment induces apoptosis and cell cycle disruption in these cells both in vitro and in vivo. In addition, NZB IL-10 knock-out mice fail to develop the B-1 clones. Dampening of IL-10 protein production via antisense IL-10 oligonucleotide treatment is correlated with decreased p27/Kip1 protein expression which results in increased cyclin D2, cyclin E and cyclin A associated kinase activity. The action of the antisense oligonucleotides is through alterations in cell cycle regulation, resulting in accelerated cell cycle progression, a G2/M block which culminates in apoptosis induction in the malignant cells. This implies that the role of IL-10 as an autocrine growth factor in malignant B-1 cells lies in its ability to inhibit apoptosis induction through the maintenance of sustainable cell cycle progression in malignant cells.

Overexpression of p21(waf1) in human T-cell lymphotropic virus type 1-infected cells and its association with cyclin A/cdk2

Human T-cell lymphotropic virus type 1 (HTLV-1) is associated with adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). T-cell transformation is mainly due to the actions of the viral phosphoprotein Tax. Tax interacts with multiple transcriptional factors, aiding the transcription of many cellular genes. Here, we report that the cyclin-dependent kinase inhibitor p21/waf1 is overexpressed in all HTLV-1-infected cell lines tested as well as in ATL and HAM/TSP patient samples. Tax was found to be able to transactivate the endogenous p21/waf1 promoter, as detected by RNase protection, as well as activate a series of wild-type and 5'-deletion constructs linked to a luciferase reporter cassette. Wild-type but not a mutant form of Tax (M47) transactivated the p21/waf1 promoter in a p53-independent manner and utilized a minimal promoter that contained E2A and TATA box sequences. The p21/waf1 protein was reproducibly observed to be complexed with cyclin A/cdk2 and not with any other known G(1), S, or G(2)/M cyclins. Functionally, the association of p21/cyclin A/cdk2 decreased histone H1 phosphorylation in vitro, as observed in immunoprecipitations followed by kinase assays, and affected other substrates, such as the C terminus of Rb protein involved in c-Abl and histone deacetylase-1 (HDAC1) regulation. Interestingly, upon the use of a stress signal, such as gamma-irradiation, we found that the p21/cyclin A/cdk2 complex was able to block all known phosphorylation sites on the Rb molecule. Finally, using elutriated cell cycle fractions and a stress signal, we observed that the HTLV-1-infected T cells containing wild-type Tax, which had been in early or mid-G(1) phase prior to gamma-irradiation, arrested in G(1) and did not undergo apoptosis. This may be an important mechanism for an oncogenic virus such as HTLV-1 to stop the host at the G(1)/S boundary and to repair the damaged DNA upon injury, prior to S-phase entry.

Inhibition of T cell activation by an autoantibody induced by murine retrovirus infection

This report describes a murine monoclonal IgM antibody, 6E3.C4, induced by retrovirus infection of BALB/ c-H-2b mice which inhibits mitogen stimulation of both mouse and human lymphocytes in vitro. The molecule bound by this antibody appears to be an activation antigen since binding is upregulated by mitogen stimulation. Analysis of the epitope bound by mAb 6E3.C4 revealed that it is associated with a 52-kDa protein with a pI of approximately 5.7 as determined by Western blot analysis. A protein expressing this or a cross-reactive epitope was isolated and determined to be alpha-tubulin by amino acid sequencing. Reactivity with purified alpha-tubulin confirms this identification. These findings suggest a potential role for a cell surface molecule that is either alpha-tubulin or a cross-reactive molecule in the activation processes of T cells.