SAMHD1 expression contributes to doxorubicin resistance and predicts survival outcomes in diffuse large B-cell lymphoma patients

Diffuse large B-cell lymphoma (DLBCL) is a commonly diagnosed, aggressive non-Hodgkin's lymphoma. While R-CHOP chemoimmunotherapy is potentially curative, about 40% of DLBCL patients will fail, highlighting the need to identify biomarkers to optimize management. SAMHD1 has a dNTPase-independent role in promoting resection to facilitate DNA double-strand break (DSB) repair by homologous recombination. We evaluated the relationship of SAMHD1 levels with sensitivity to DSB-sensitizing agents in DLBCL cells and the association of SAMHD1 expression with clinical outcomes in 79 DLBCL patients treated with definitive therapy and an independent cohort dataset of 234 DLBCL patients. Low SAMHD1 expression, Vpx-mediated, or siRNA-mediated degradation/depletion in DLBCL cells was associated with greater sensitivity to doxorubicin and PARP inhibitors. On Kaplan-Meier log-rank survival analysis, low SAMHD1 expression was associated with improved overall survival (OS), which on subset analysis remained significant only in patients with advanced stage (III-IV) and moderate to high risk (2-5 International Prognostic Index (IPI)). The association of low SAMHD1 expression with improved OS remained significant on multivariate analysis independent of other adverse factors, including IPI, and was validated in an independent cohort. Our findings suggest that SAMHD1 expression mediates doxorubicin resistance and may be an important prognostic biomarker in advanced, higher-risk DLBCL patients.

Entropy-driven nonequilibrium phonon-stimulated electron-phonon coupling in tin dioxide nanorods

Nonequilibrium (NEQ) phonon fluctuation in a nanosystem has been studied through the statistical assessment of the entropy-production and -consumption events in ultrasmall tin dioxide (SnO_{2}) nanorods. Size- and shape-dependent alteration in free energy leading to modulation of the probability distribution function of the phonon dynamics has been observed from the x-ray diffraction and Raman scattering characterizations. The Gallavotti-Cohen nonequilibrium fluctuation theorem has been utilized to qualitatively describe the aforementioned behaviors under the influence of a global flux. The observation of entropy consumption and thermodynamically favorable entropy-production events indicates the presence of NEQ fluctuations in the phonon modes. The effective energy scale of fluctuation in driven phonon modes, dissipating energy faster than relaxation time, is quantified on the order of nanojoules. From optical absorption and photoluminescence studies, the observation of the electron-phonon coupled state confirms the interaction of the NEQ phonons with electrons. The strength of the coupling has been estimated from the temperature-independent Barry center shift and found to be enhanced to 5.35. Valence band x-ray photoelectron spectroscopy and Fourier transformed infrared spectroscopy analyses reconcile NEQ phonon mediated alteration of the valence band density of states, activation of silent phonon modes, and superior excitonic transitions, suitable for the new generation of ultrafast quantum device applications.

Observation of non-equilibrium fluctuation in the shear-stress-driven hemoglobin aggregates

Non-equilibrium fluctuations caused by the rearrangement of hemoglobin molecules into an aggregate state under shear stress have been investigated experimentally. The flow response under the shear stress (σ) corroborates the presence of contrasting aggregate and rejuvenation states governed by entropy production and consumption events. From the time-dependent shear rate fluctuation studies of aggregate states, the probability distribution function (PDF) of the rate of work done is observed to be spread from negative to positive values with a net positive mean. The PDFs follow the steady-state fluctuation theorem, even at a smaller timescale than that desired by the theorem. The behavior of the effective temperature (Teff) that emerges from a non-equilibrium fluctuation and interconnects with the structural restrictions of the aggregate state of our driven system is observed to be within the boundary of the thermodynamic uncertainty. The increase in Teff with the applied σ illustrates a phenomenal nonlinear power flux-dependent aggregating behavior in a classic bio-molecular-driven system.

Correlation of Dose Volume Parameters with Dysphagia and Pharyngeal Constrictor Muscle Thickness in Dysphagia Optimized IMRT

PURPOSE/OBJECTIVE(S)

Reduced radiation dose to the pharyngeal constrictor muscles (PCM) using dysphagia optimized intensity-modulated RT (DO-IMRT) is associated with improved swallowing outcomes in oropharyngeal cancers (OPCs). Purpose was to evaluate the relationship between dose of radiation delivered and acute dysphagia in patients with OPC treated with IMRT, after delineation of PCM.

MATERIALS/METHODS

Twenty-five patients with newly diagnosed OPC who underwent definitive IMRT with concurrent cisplatin were included in the study. PCM mean dose < 50 Gy was used as the dose constraint. Target volume was divided into high, intermediate and low risk areas receiving doses in the range of 60-66 Gy, 54-58 Gy, 51-56 Gy in 30-33 fractions over 6-6.5 weeks, respectively. PCM dose-volume parameters were collected and logistic regression was used to analyze these data relative to percent weight loss during RT and duration of feeding tube use. Thickness of constrictor muscle in pre-treatment and 3 months post-therapy CT scan were assessed. Weekly assessment of dysphagia was based on RTOG toxicity gradings. Aim of the study was to evaluate the correlation between dysphagia grades with dose-volume parameters and PCM thickness.

RESULTS

Median age was 55.0 years (mean 54.3) with 24 males and stage II:III-16:9 patients. Dmean to PCM was 49.86 Gy (range 48.22 -57.63) with median Dmax of 70.24 Gy. For patients with dysphagia (grade ≥1), V50 ranged from 48.2-57.23%, while in those with no dysphagia, it ranged from 47.92-52.18 % (Mean 51.36%). Nine patients needed feeding tube after RT end. Median feeding tube duration was 64 days. The correlation between Dmean ≥ 50 Gy and dysphagia at 1st, 2nd, 3rd and 6th month was found statistically significant (p < 0.01). Table 1 shows the Pearson correlation and P-value of the dosimetric parameters with dysphagia. The correlation of V50 was found statistically significant with grade of dysphagia at 3rd and 6th month post-treatment (p<0.001). The mean thickness range and median thickness of constrictors before and 3 months after treatment were 1.8-3.2 mm, 2.4 mm, and 2.8-6.2 mm,4.1 mm, respectively. The increase in thickness of constrictor muscle correlated significantly (p<0.05) with dysphagia grades and also with V50, V60 and Dmean (p<0.001) but no statistical significance was seen with Dmax (p = 0.232). With a median follow-up of 18 months (range 7-24), 1-year actuarial local control was 92%.

CONCLUSION

DO-IMRT may prove beneficial in the OPC by preventing dysphagia and aspiration post therapy and hence improving the quality of life of patients. Dmean ≥ 50Gy, V50 > 51.4% and V60 > 35.5% are the parameters correlating significantly with dysphagia (p<0.001) and change in mean thickness of PCM (p<0.001).

DNA-PK is activated by SIRT2 deacetylation to promote DNA double-strand break repair by non-homologous end joining

DNA-dependent protein kinase (DNA-PK) plays a critical role in non-homologous end joining (NHEJ), the predominant pathway that repairs DNA double-strand breaks (DSB) in response to ionizing radiation (IR) to govern genome integrity. The interaction of the catalytic subunit of DNA-PK (DNA-PKcs) with the Ku70/Ku80 heterodimer on DSBs leads to DNA-PK activation; however, it is not known if upstream signaling events govern this activation. Here, we reveal a regulatory step governing DNA-PK activation by SIRT2 deacetylation, which facilitates DNA-PKcs localization to DSBs and interaction with Ku, thereby promoting DSB repair by NHEJ. SIRT2 deacetylase activity governs cellular resistance to DSB-inducing agents and promotes NHEJ. SIRT2 furthermore interacts with and deacetylates DNA-PKcs in response to IR. SIRT2 deacetylase activity facilitates DNA-PKcs interaction with Ku and localization to DSBs and promotes DNA-PK activation and phosphorylation of downstream NHEJ substrates. Moreover, targeting SIRT2 with AGK2, a SIRT2-specific inhibitor, augments the efficacy of IR in cancer cells and tumors. Our findings define a regulatory step for DNA-PK activation by SIRT2-mediated deacetylation, elucidating a critical upstream signaling event initiating the repair of DSBs by NHEJ. Furthermore, our data suggest that SIRT2 inhibition may be a promising rationale-driven therapeutic strategy for increasing the effectiveness of radiation therapy.

Analyzing the impact of close margins and extra-resection margins on failure rates in postoperative oral cavity cancers

BACKGROUND

Postoperative oral cancers with close margins belong to medium- to high-risk category for local failure. During re-surgery for close margins, there is sufficient doubt as to whether the re-excised tissue is from the same region as the close margin. Therefore, we planned a retrospective review of these cases of close margins that were re-excised with extra-resection margins (ERMs).

MATERIAL AND METHODS

Details of 2011 oral cavity patients resected at our hospital were retrieved. Cases with close margins were segregated and the status of ERMs was noted. The postoperative histopathological details, radiotherapy details, and failure patterns in all these cases were documented. The primary objective of the study was to assess the overall survival (OS) and disease-free survival (DFS) in cases with ERMs. The secondary objective was to assess the local and regional control rates and variation with the number and status of close and ERMs. OS, DFS, and local failure rates were defined from the date of registration. Statistical analysis was performed with the SPSS statistical software package. All survival analyses were performed using the Kaplan-Meier method. Log-rank test was used to test the statistical significance. A P-value of 0.05 was considered statistically significant.

RESULTS

Sixty-four cases with a median age of 47 years (range: 29-76) were considered for the final analysis. The median follow-up was 40 months (range: 9.5-56.5). The 2-year OS and DFS rates were 91.5% and 88.5%, respectively. The crude local and regional failure rates were 10.9% and 3.1%, respectively. The 3-year locoregional control rate was 90.2%. The 2-year locoregional control rate for one close margin was significantly better as compared to more than one close margin (P = 0.049). No difference in survival and failure rates was found between the number of ERMs resected (one vs. two) and ≤ vs. > 3 mm close margin status. Two patients developed bone metastases.

CONCLUSION

The survival rates and locoregional control rates did not differ much between the groups that had one or more ERMs. However, the locoregional control rates were better in cases with one close margin as compared to those with more than one close margin. A larger study with longer follow-up is needed to detect statistically significant differences in outcomes and identify the factors that portend poor prognosis in these cases with close margins and ERMs.

222 TOWARDS A DELIRIUM FRIENDLY EMERGENCY DEPARTMENT

Background

Delirium affects approx. 10-30 % of patients over the age of 65. Up to 70% of cases are missed in the Emergency Department (ED). Delirium results in increased morbidity, mortality, increased length of stay and decreased functional status with increased discharges to residential care centres. Delirium in the ED is an independent predictor of death within 6 months.

Methods

We completed an audit which showed 40% of those &gt; 65 years of age in the ED were delirious and 60% of those had dementia. None of these had been identified as delirious prior to review. We have approx. 5,000 patients &gt;75 years of age attending our ED annually (1/7th of presentations). This audit was used as a catalyst for our quality improvement project. We established a steering group with a small quality improvement sub-committee. We combed the literature, identified areas for improvement and costed our project. We also looked at reliance on 1:1 carers for those with delirium and potential benefits to patient, staff and management.

Results

We used the SPARK ignite programme as a means to gain momentum and also educate ourselves on business management and change management. We competed in the finals with our “delirium package” – focussing on orientation, stimulation, safety and education. These 4 pillars of delirium care have been shown to prevent delirium, reduce hospital stay for those with delirium and also augment their delirium cycle. Competing and winning a prize highlighted the importance of delirium care and brought our project to a bigger stage.

Conclusion

Due to our multi-disciplinary team composed of non-consultant hospital doctors, advanced nurse practitioners and occupational therapists, we have been able to introduce the national dementia programme for early identification of delirium in the emergency department. We now have a space for managing those with delirium and have received funding to put our package in place. This can be replicated in hospitals around the country highlighting the non-pharmacological treatments for delirium.

Maintenance therapy with a poly(ADP-ribose) polymerase inhibitor in patients with newly diagnosed advanced epithelial ovarian cancer: individual patient data and trial-level meta-analysis

Background

We synthesize the efficacy and toxicity of poly(ADP-ribose) polymerase inhibitors (PARPis) in patients with newly diagnosed advanced ovarian cancer.

Patients and methods

We manually extracted individual patient data (IPD) for progression-free survival (PFS) from published survival curves of randomized controlled trials (RCTs) that compared PARPi versus placebo as maintenance therapy in first-line treatment, for whole study populations and subgroups, based on BRCA1/BRCA2 mutation (germline and/or somatic) and homologous recombination deficiency (HRD) status, using WebPlotDigitizer software. The respective PFS curves for each study and combined population were reconstructed from extracted IPD. The primary outcome was PFS in combined whole population and subgroups.

Results

In IPD analysis of combined population from three RCTs, with 2296 patients and 1287 events, PFS was significantly longer in PARPi versus placebo [median 20.4 (95% confidence interval (CI) 18.6-21.9) versus 14.9 (95% CI 13.9-16.5) months, respectively; hazard ratio (HR) 0.67, 95% CI 0.60-0.75; P < 0.001]. In IPD subgroup analyses from four eligible RCTs (2687 patients and 1485 events), median PFS was significantly longer in PARPi versus placebo arm, in the BRCA-mutated (45.7 versus 17.7 months, respectively; HR 0.38, 95% CI 0.32-0.46; P < 0.001), HRD-positive including BRCA-mutated (34.7 versus 17.9 months, respectively; HR 0.45, 95% CI 0.38-0.54; P < 0.001), and HRD positive excluding BRCA-mutated (22.3 versus 13.1 months, respectively; HR 0.47, 95% CI 0.34-0.65; P < 0.001) subgroups, but not in the HRD-negative (15.0 versus 11.3 months, respectively; HR 0.90, 95% CI 0.76-1.05; P = 0.75) subgroup. Results of trial-level meta-analysis were concordant with IPD analysis in whole population and subgroups.

Conclusions

Among newly diagnosed ovarian cancer patients, PARPi maintenance therapy significantly improves PFS in those with germline and/or somatic BRCA mutation and/or HRD-positive tumor but not in those with HRD-negative tumor.

•

Maintenance PARPi resulted in significant PFS improvement in total population, but benefit varied in subgroups.

•

PARPi showed PFS gain in BRCA-mutated (45.7 versus 17.7 m) and HRD-positive subgroups.

•

No significant PFS benefit was seen in the HRD-negative subgroup (15.0 versus 11.3 months; P = 0.75).

•

PARPi should be a standard treatment in newly diagnosed ovarian cancer patients except those with HRD-negative tumors.