Observation of electron neutrino appearance in a muon neutrino beam

The T2K experiment has observed electron neutrino appearance in a muon neutrino beam produced 295 km from the Super-Kamiokande detector with a peak energy of 0.6 GeV. A total of 28 electron neutrino events were detected with an energy distribution consistent with an appearance signal, corresponding to a significance of 7.3σ when compared to 4.92±0.55 expected background events. In the Pontecorvo-Maki-Nakagawa-Sakata mixing model, the electron neutrino appearance signal depends on several parameters including three mixing angles θ12, θ23, θ13, a mass difference Δm(32)(2) and a CP violating phase δ(CP). In this neutrino oscillation scenario, assuming |Δm(32)(2)|=2.4×10(-3)  eV(2), sin(2)θ(23)=0.5, and Δm322>0 (Δm(32)(2)<0), a best-fit value of sin(2)2θ(13)=0.140(-0.032)(+0.038) (0.170(-0.037)(+0.045)) is obtained at δ(CP)=0. When combining the result with the current best knowledge of oscillation parameters including the world average value of θ(13) from reactor experiments, some values of δ(CP) are disfavored at the 90% C.L.

Defining acute ischemic stroke tissue pathophysiology with whole brain CT perfusion

BACKGROUND

This study aimed to identify and validate whole brain perfusion computed tomography (CTP) thresholds for ischemic core and salvageable penumbra in acute stroke patients and develop a probability based model to increase the accuracy of tissue pathophysiology measurements.

METHODS

One hundred and eighty-three patients underwent multimodal stroke CT using a 320-slice scanner within 6hours of acute stroke onset, followed by 24hour MRI that included diffusion weighted imaging (DWI) and dynamic susceptibility weighted perfusion imaging (PWI). Coregistered acute CTP and 24hour DWI was used to identify the optimum single perfusion parameter thresholds to define penumbra (in patients without reperfusion), and ischemic core (in patients with reperfusion), using a pixel based receiver operator curve analysis. Then, these results were used to develop a sigma curve fitted probability based model incorporating multiple perfusion parameter thresholds.

RESULTS

For single perfusion thresholds, a time to peak (TTP) of +5seconds best defined the penumbra (area under the curve, AUC 0.79 CI 0.74-0.83) while a cerebral blood flow (CBF) of < 50% best defined the acute ischemic core (AUC 0.73, CI 0.69-0.77). The probability model was more accurate at detecting the ischemic core (AUC 0.80 SD 0.75-0.83) and penumbra (0.85 SD 0.83-0.87) and was significantly closer in volume to the corresponding reference DWI (P=0.031).

CONCLUSIONS

Whole brain CTP can accurately identify penumbra and ischemic core using similar thresholds to previously validated 16 or 64 slice CTP. Additionally, a novel probability based model was closer to defining the ischemic core and penumbra than single thresholds.

Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia

Extremely poor growth of some individuals within a birth cohort (runting) is a significant problem in crocodile farming. We conducted a pathological investigation to determine if infectious disease is associated with runting in farmed saltwater crocodiles ( Crocodylus porosus) and to look for evidence of other etiologies. In each of 2005 and 2007, 10 normal and 10 runt crocodiles, with an average age of 5.5 months and reared under identical conditions, were sampled. Laboratory testing included postmortem; histological examination of a wide variety of tissues (with quantitation of features that were noted subjectively to be different between groups); hematology; serum biochemistry (total protein, albumin, globulins, total calcium, phosphorus, and iron); bacterial culture of liver and spleen (2005 only); viral culture of liver, thymus, tonsil, and spleen using primary crocodile cell lines (2007 only); and serum corticosterone (2007 only). The only evidence of infectious disease was mild cutaneous poxvirus infection in 45% of normal and 40% of runt crocodiles and rare intestinal coccidia in 5% of normal and 15% of runt crocodiles. Bacterial and viral culture did not reveal significant differences between the 2 groups. However, runt crocodiles exhibited significant ( P < .05) increases in adrenocortical cell cytoplasmic vacuolation and serum corticosterone, decreased production of bone (osteoporosis), and reduced lymphoid populations in the spleen, tonsil, and thymus. Runts also exhibited moderate anemia, hypoalbuminemia, and mild hypophosphatemia. Taken together, these findings suggest an association between runting and a chronic stress response (hyperactivity of the hypothalamic-pituitary-adrenal axis).

Measurement of neutrino oscillation parameters from muon neutrino disappearance with an off-axis beam

The T2K Collaboration reports a precision measurement of muon neutrino disappearance with an off-axis neutrino beam with a peak energy of 0.6 GeV. Near detector measurements are used to constrain the neutrino flux and cross section parameters. The Super-Kamiokande far detector, which is 295 km downstream of the neutrino production target, collected data corresponding to 3.01×10(20) protons on target. In the absence of neutrino oscillations, 205±17 (syst) events are expected to be detected while only 58 muon neutrino event candidates are observed. A fit to the neutrino rate and energy spectrum, assuming three neutrino flavors and normal mass hierarchy yields a best-fit mixing angle sin2(θ23)=0.514±0.082 and mass splitting |Δm(32)(2)|=2.44(-0.15)(+0.17)×10(-3) eV2/c4. Our result corresponds to the maximal oscillation disappearance probability.

Abstract P5-20-05: A Phase 2 trial of RAD 001 and Carboplatin in patients with triple negative metastatic breast cancer

BACKGROUND: RAD001 is an oral mTOR inhibitor that has exhibited activity in breast cancer. Triple negative breast cancer cells are unable to repair double stranded DNA breaks and hence have sensitivity to platinum agents that cause interstrand cross-links. Rapamycin acts synergistically with platinum agents to induce apoptosis and inhibit proliferation in at least two different breast cancer cell lines (including ER/PR negative cell lines). We propose that combination RAD001 and carboplatin may have activity in triple-negative breast cancer.

MATERIALS AND METHODS: The primary objective of the study is to determine clinical benefit (complete remission (CR) + partial remission (PR) + stable disease (SD more than 6 months)) and the toxicity of this combination in triple negative metastatic breast cancer who have had 0–3 prior chemotherapy regimens for metastatic disease. Twenty-five subjects were to be entered in this Phase II study. This design has greater than 80% power to test the null hypothesis that the clinical benefit rate is less than or equal to 10% versus the alternative hypothesis that clinical benefit rate is greater than or equal to 30%. Prior carboplatin is allowed. Women with treated brain metastasis are eligible. Secondary objectives are to determine progression free survival and relationship between pretreatment sensitivity (biopsy at baseline) and clinical response (biopsy post 2 cycles) using IHC staining for abundance of key proteins in the Akt-mTOR pathway and their activity using surrogate phosphorylation site-specific antibodies. According to the original study plan, carboplatin AUC 6, was to be given intravenously every three weeks. Five mg of RAD001 was to be given daily with a 3 patient run-in and then 10 mg daily if there were no dose-limiting toxicities. Due to a surprising amount of thrombocytopenia with this combination the dose of carboplatin was first amended to AUC 5 and most recently to AUC 4 with 5 mg of RAD001 (and no plan to escalate to 10 mg).

RESULTS: 23 patients of a planned 25 have been recruited thus far. Median age is 59. Of the 20 patients assessable for response at this time, there have been 1 CR, 5 PRs, 8 SDs and 6 PDs. One SD was achieved in a patient progressing on single agent Carboplatin at study entry. Median duration of CR+ SD +PR thus far is 13 weeks (range: 6–74 weeks). 5 of 22 patients assessable for toxicity had grade 3/4 thrombocytopenia and 4 patients had grade 3 neutropenia (no febrile neutropenia). 13 out of eighteen patients have had treatment held and/or dose reductions secondary to hematological toxicity, however, since amendment for starting dose of Carboplatin to AUC 4 the regimen has been very well tolerated with only 1 out of eleven patients with grade 3 neutropenia and grade 3 thrombocytopenia. 1 patient suffered from grade 3 dehydration. The estimated clinical benefit rate is 45% (95% confidence interval: 23%, 67%). Median time to progression or death is 85 days from start of treatment.

CONCLUSIONS: Our study has met the primary end point of demonstrating clinical benefit in triple negative metastatic breast cancer. Dose limiting thrombocytopenia was an unexpected side effect requiring protocol amendment. We continue to accrue study subjects at the amended dosing.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-20-05.

Abstract P2-05-01: Gene expression changes associated with response to neoadjuvant chemotherapy are observed early in treatment: results from the I-SPY 1 TRIAL (CALGB 150007/150012; ACRIN 6657)

Background: Prior gene expression profiling studies have identified markers that are predictive of chemotherapy response using pre-treatment biopsies. However, this approach does not account for chemotherapy-induced perturbation in signaling within tumors early in treatment that may predict response to therapy with superior sensitivity to baseline signatures. We hypothesized that measuring early changes in gene expression induced by neoadjuvant chemotherapy might yield improved markers of treatment efficacy and patient outcome.

Methods: Transcriptome data from 34K probe cDNA microarrays were assembled using serial biopsies obtained from 36 I-SPY 1 TRIAL patients before treatment (T1), and 24-72 hours after beginning neoadjuvant anthracycline-based chemotherapy (T2). Outcome parameters included residual cancer burden (RCB) after therapy and recurrence free survival (RFS). Gene expression changes occurring between T1 and T2 (T2-T1) were compared between known responders (RCB 0/1) and non-responders (RCB 2/3) using a permutation test based on the t-statistic; Cox proportional hazards modeling was used to identify early response genes associated with RFS. Due to the small sample sizes, we adopted a relaxed significance threshold for outcome associations (p-value&lt;0.005 without multiple testing correction). Pathway analyses were performed with Ingenuity IPA software.

Results: 97 genes were found to be differentially altered upon comparing early gene expression changes (T2-T1) between responders (RCB 0/1) and non-responders (RCB 2/3). Ingenuity IPA software identified cell cycle as the top enriched pathway (p = 0.0008) among these differentially altered genes, with responders showing relative up-regulation of translation regulator EIF4EBP1 and cell cycle regulators CDKN2B and SMARCB1 after treatment. Survival analysis identified changes (T2-T1) in 293 genes as significantly associated with RFS; these genes were enriched in pathways including lipid antigen presentation by CD1, cell death and drug metabolism, and notch signaling. Surprisingly, only 4 genes were associated with both RCB and RFS, likely reflecting a prognostic signal from the many non-responding patients with favorable outcomes. Intrinsic subtype assignments were 75% concordant between time points T1 and T2, with basal classifications remaining stable (13/13) and some inter-conversion among LumA, LumB, Her2, and Normal (9/23). Interestingly, a larger number of genes were associated with chemotherapy response when one considered the change in expression (T2-T1), rather than absolute expression levels at T1 (17 genes) or at T2 (87 genes). Moreover, there was negligible overlap between these three response associated gene sets (T1, T2, and T2-T1 change), indicating that early expression changes may provide information beyond signatures obtained at static time points.

Conclusion: These analyses suggest that pre-treatment, early treatment and early changes provide non-redundant information on chemotherapy responsiveness and outcome. Early expression changes might be combined with data from pre-treatment biopsies to construct early predictors of non-response, an essential component within an adaptive treatment framework.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-05-01.