Characteristics of Four Upward-Pointing Cosmic-Ray-like Events Observed with ANITA

We report on four radio-detected cosmic-ray (CR) or CR-like events observed with the Antarctic Impulsive Transient Antenna (ANITA), a NASA-sponsored long-duration balloon payload. Two of the four were previously identified as stratospheric CR air showers during the ANITA-I flight. A third stratospheric CR was detected during the ANITA-II flight. Here, we report on characteristics of these three unusual CR events, which develop nearly horizontally, 20-30 km above the surface of Earth. In addition, we report on a fourth steeply upward-pointing ANITA-I CR-like radio event which has characteristics consistent with a primary that emerged from the surface of the ice. This suggests a possible τ-lepton decay as the origin of this event, but such an interpretation would require significant suppression of the standard model τ-neutrino cross section.

The influence of litter size and favourable conditions on mortality and weaning weights in rats

Litters of 12 pups produced the optimum results for survival ( P<0·005) and for weaning weights ( P<0·05) when compared with litters of 8 and 10 pups. This number is similar to the normal litter size and normal number of teats in rats. In our study, the normal litter size was X = 12·5. Our results were obtained under favourable conditions without disturbing the animals and facilitating access to food and water for the mothers and pups.

Abstract P6-13-08: Palbociclib and paclitaxel on an alternating schedule for advanced breast cancer: Results of a phase Ib trial

Background: Palbociclib (P) is an oral CDK 4/6 inhibitor (CDKi) that was recently FDA approved in combination with endocrine therapy for metastatic breast cancer. We have performed a Phase I trial of P in combination with paclitaxel (T) based on preclinical studies suggesting that P synergizes with T when given on an alternating schedule, enabling cell cycle synchronization in tumor cells. We now present the dose expansion cohort.

Methods: Patients (Pts) enrolled on the trial had Rb-expressing tumors of any estrogen/progesterone/HER2 receptor type, adequate organ function, and ≤3 prior chemotherapy regimens for metastatic breast cancer (mBC). Prior adjuvant or metastatic taxane was allowed. Dose escalation led to expansion at P100mg or 75mg, starting with 3 days of P (run-in) and reduction of P dosing from 5-day to 3-day intervals (days 2-4, 9-11, 16-18 of each 28 day cycle). T at 80mg/m2 was given weekly for 3 cycles; thereafter, T was administered days 1, 8 and 15 of 28 day cycle. Weekly toxicity assessments were performed; RECIST 1.0 response was assessed every 2 cycles as partial response (PR), stable disease (SD) or progressive disease (PD). Pts had the option to discontinue T and continue on P alone (3 on/1 off schedule) if they attained SD after cycle 6.

Results: 27 pts enrolled on study (15- dose escalation, 12- dose expansion). Results are shown in the Table. 21 pts had received prior taxane; pts had received a median of 2 chemotherapy regimens for mBC. DLTs were grade 3 AST/ALT (n=1, at 125 mg) and febrile neutropenia (FN) (n=1, at 100 mg). Uncomplicated grade 3/4 NTP was common and frequently led to dose reduction or dose interruption during the first cycle of therapy. Frequency of NTP did not change with reducing the days of P. Among 24 evaluable patients, 14 (58%), had PR or SD ≥ 6 months across all dose levels. Of 14 pts who responded, 10 (71%) had received prior taxane. 20 pts are off study; 19 for PD, and 2 for toxicity (NTP in cycle 17 and FN in cycle 1); 7 pts remain on study. Prolonged tumor responses were seen.

Conclusions: P and T can be safely combined on an alternating dosing schedule; the optimal combination dose is 75 mg of P and 80mg/m2 of weekly T. The high response rate warrants a randomized trial to determine the incremental benefit over T alone. Additional mechanistic studies are in progress to understand the in vivo effects of the alternating dosing schedule on cell cycle activity and tumor proliferation.

Starting Dose Level P (mg)Number (Total 27)DLTGrade 3/4 NTP (n)Final Dose P mg (n)Dose Interruption (n)Best Response (n)5030050 (1) 50 (1) 50 (1)No (2) Yes (1)PR (1) SD (1) PD (1)7530275 (1) 50 (1) 25 (1)No (1) Yes (2)PR (2) SD (1)100605100 (2) 75 (3) 25 (1)No (1) Yes (5)PR (2) SD (1) PD (3)12531- LFT375 (1) 50 (2)No (0) Yes (3)PR (1) SD (2)75 (Run-In)60175 (5) 50 (1)No (4) Yes (2)PR (1) SD (2) PD (1) N/A (2)*100 (Run-In)61- FN5100 (1) 75 (4) 25(1)No (1) Yes (5)PR (4) SD (1) N/A (1)^*2 pts not yet evaluable. ^1 pt went off study due to FN after cycle 1.

Citation Format: Clark AS, O'Dwyer P, Troxel A, Lal P, Feldman M, Gallagher M, Driscoll A, Colameco C, Lewis D, Rosen M, Matro J, Bradbury A, Domchek S, Fox K, DeMichele A. Palbociclib and paclitaxel on an alternating schedule for advanced breast cancer: Results of a phase Ib trial. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-13-08.

Invited Article: miniTimeCube

We present the development of the miniTimeCube (mTC), a novel compact neutrino detector. The mTC is a multipurpose detector, aiming to detect not only neutrinos but also fast/thermal neutrons. Potential applications include the counterproliferation of nuclear materials and the investigation of antineutrino short-baseline effects. The mTC is a plastic 0.2% (10)B-doped scintillator (13 cm)(3) cube surrounded by 24 Micro-Channel Plate (MCP) photon detectors, each with an 8 × 8 anode totaling 1536 individual channels/pixels viewing the scintillator. It uses custom-made electronics modules which mount on top of the MCPs, making our detector compact and able to both distinguish different types of events and reject noise in real time. The detector is currently deployed and being tested at the National Institute of Standards and Technology Center for Neutron Research nuclear reactor (20 MWth) in Gaithersburg MD. A shield for further tests is being constructed, and calibration and upgrades are ongoing. The mTC's improved spatiotemporal resolution will allow for determination of incident particle directions beyond previous capabilities.

Abstract P3-08-18: Association of tamoxifen use and ovarian aging in patients with invasive or pre-invasive breast cancer

Background: The use of tamoxifen has been shown to delay the recovery of chemotherapy-induced amenorrhea, however the independent impact of long-term endocrine therapy on ovarian aging is not known, and to our knowledge, has never been directly investigated. Understanding the effect of endocrine therapy on ovarian aging will help breast cancer patients of reproductive age make more informed and empowered decisions regarding their treatment. The aim of this study is to explore the relationship between tamoxifen therapy and age onset of menopause.

Methods: We conducted a retrospective cohort study using patients identified through the UCSF Cancer Registry and UCSF SPORE database. Women who were diagnosed with Stage 1-3 invasive or in situ breast cancer between 1985 and 2011, who were premenopausal at the time of diagnosis and who did not receive systemic chemotherapy were included. Patients with recurrent disease and prior ovarian surgery were excluded. Eligibility was confirmed by telephone, and online or paper surveys were distributed to eligible subjects only. Age onset of menopause was the primary endpoint of the study and was defined as the age at which a woman had her last period and no menses for 12 months. Age onset of menopause was assessed through surveys. The primary analysis compared age onset of menopause between subjects who received tamoxifen for any duration and control subjects who never received tamoxifen. Secondary analyses were performed using a Cox proportional hazards model to determine whether duration of tamoxifen exposure and age of tamoxifen initiation impacted age onset of menopause in subjects treated with tamoxifen.

Results: A total of 1137 potential subjects believed to meet eligibility criteria were identified and called, and 649 subjects were reached. Eligibility was confirmed by phone in 340 subjects. A total of 336 subjects consented to participate in the study, and 262 (78%) completed and returned the survey. 227 subjects were included in the primary analysis of which 110 subjects received prior tamoxifen, and 117 subjects received no prior tamoxifen. At the time of the survey, 16.3% vs. 20.2% of patients under age 50 that were exposed and not exposed to tamoxifen entered menopause, respectively. The median age onset of menopause was 50.94 and 51.34 for the tamoxifen and no tamoxifen groups, respectively. The hazard ratio between these groups was 1.077 which was not statistically significant (p = 0.6917). No association (p = 0.55) was found between the duration of tamoxifen use and the age onset of menopause. When controlling for tamoxifen duration, there was no significant difference (p = 0.93) in age onset of menopause between subjects who initiated tamoxifen prior to age 45 and those who initiated at age 45 or older.

Conclusion: These data suggest that tamoxifen alone is not associated with an earlier age onset of menopause, and that tamoxifen use, in the absence of systemic chemotherapy, is unlikely to significantly accelerate ovarian aging.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-08-18.

Abstract P2-02-04: Kinetic heterogeneity features on breast DCE-MRI as prognostic markers of breast cancer recurrence

PURPOSE

Breast tumors have been shown to be heterogeneous lesions, and tumor heterogeneity is one of the major difficulties in the way of an effective cancer diagnosis and successful treatment. We evaluate the predictive capacity of DCE-MRI kinetic heterogeneity features for assessing the risk of breast cancer recurrence as determined by a validated tumor gene expression assay.

METHOD AND MATERIALS

Bilateral Breast DCE-MRI scans were retrospectively analyzed from 57 women with estrogen receptor positive/node negative invasive breast cancer. The ages of the women at the time of the imaging ranged from 37 to 74 years with a mean age of 55.5 years. The women were imaged prone in a 1.5T scanner (GE LX echo, GE Healthcare, or Siemens Sonata, Siemens); matrix size: 512 × 512; slice thickness: 2.4-4.4 mm; flip angle: 25° or 30°. The images were collected before and after the administration of gadodiamide (Omniscan) or gadobenate dimeglumine (MultiHance) contrast agents. Dynamic contrast enhanced images were acquired at 90 second intervals for 3 post contrast time points. The women had previously undergone Oncotype Dx (Genomic Health Inc.) profiling of their tumor. The Oncotype DX assay provides the likelihood of 10-year breast cancer recurrence, using a score stratified into 3 risk categories (risk: low ≤17, medium = 18-30, high ≥ 31). Pixel-wise relative enhancement curves were computed using three post-contrast time points. Fuzzy C-means clustering was applied to partition the tumor pixels according to the variance of their relative enhancement. To capture kinetic heterogeneity, wavelet features were extracted within each tumor partition as a measure of spatial variation. Mean and variance of these features were further estimated within each region. Using these features, multivariable logistic regression was performed with leave-one-out cross-validation and feature selection to classify the tumors as high or low/medium risk. We compared our kinetic heterogeneity features against standard kinetics and texture features. Area under the curve (AUC) of the receiver operating characteristic (ROC) was used to evaluate classification performance.

RESULTS

Feature selection indicated an optimal set of 7 kinetic heterogeneity features (out of 54). The classifier based on these features had an AUC = 0.82 in classifying high versus low/medium risk tumors. Classifiers based on standard kinetics and texture features performed with AUCs of 0.69 and 0.64 respectively.

CONCLUSION

Wavelet kinetic features from breast DCE-MRI could be used to capture the spatial pattern of kinetic heterogeneity of and potentially serve as prognostic markers for the risk of recurrence. In addition, breast DCE-MRI kinetic heterogeneity features could be used to assess likelihood of recurrence and ultimately help guide therapeutic decisions. Larger studies are needed to validate these findings.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-02-04.

PD02-05: MRI Phenotype and Tumor Subtype Affect Breast Conservation Eligibility and MRI Accuracy in the I-SPY 1 Trial

Background

Neoadjuvant chemotherapy (NAC) in breast cancer allows assessment of response to treatment and increases eligibility for breast conservation treatment (BCT). We previously reported that MRI tumor phenotype (based on loss of containment) predicted response to NAC and ability to achieve BCT. Since tumor subtype can affect MRI features, we sought to validate whether MRI phenotype and/or tumor subtype affected BCT eligibility in a prospective trial, I-SPY (CALGB 150007/ACRIN 6657). We also investigated the accuracy of post-NAC MRI in determining BCT eligibility, and the distribution of tumor subtypes within MRI phenotypes with the goal of identifying clinically useful factors associated with successful BCT.

Methods

We analyzed I-SPY 1 Trial data, a multi-center, prospective NAC trial with serial MRIs. Phenotypes 1 and 2 were well defined masses, while 3, 4, and 5 were more diffuse. Subjects were considered truly eligible for BCT if tumor diameter on surgical pathology was ≤ 4 cm (based on NSABP B-06 trial criteria). Post-NAC MRI and surgical pathology were considered discrepant if longest tumor diameter differed by &gt; 2 cm. Categorical variables were compared using the chi-squared test.

Results

Of the 221 subjects, 198 had pre and post-NAC MRIs, and surgical pathology available. Of these, 174 had a tumor diameter &gt; 4 cm prior to NAC, and were considered initially ineligible for BCT. After NAC, 141 (81%) patients became BCT eligible based on having ≤4 cm of residual tumor. In contrast, 46 (26%) had pathologic complete response (pCR, no invasive tumor). The rate of becoming BCT eligible differed by hormone receptor (HR)/Her2 status (p = 0.005) and MRI phenotype (p = 0.037), with higher rates of eligibility in Her2+ and triple negative tumors, and the well defined MRI phenotypes. Overall, 75 (38%) patients had a size discrepancy between tumor diameter on post-NAC MRI and size on surgical pathology. Subjects with diffuse MRI phenotypes had more size discrepancy than phenotypes 1 and 2 (p = 0.001). Subjects with HR+/Her2- tumors also had more size discrepancy than other subtypes (p = 0.004). The more diffuse MRI phenotypes were more commonly HR+/Her2- tumors, and less commonly HR−/Her2- (p = 0.006). There was no difference in actual receipt of BCT by HR/Her2 status. However, patients with a well-defined MRI phenotype were significantly more likely to actually receive BCT than those with a diffuse MRI phenotype (47% versus 27%, p = 0.023).

Conclusions

Patients with well defined patterns on MRI and with Her2+ or triple negative disease were more likely to become eligible for BCT after NAC. The same factors that predict pCR also predict BCT eligibility, but far more patients achieve BCT eligibility than pCR. MRI after NAC was less accurate in the diffuse phenotypes, which could reflect increased difficulty in measuring tumor size in this setting. Tumor phenotype and subtype can help predict likelihood of achieving eligibility for BCT, and can be useful in setting appropriate expectations for women at the start of NAC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD02-05.

Endoscopic transnasal cryo-assisted removal of an orbital cavernous hemangioma: a technical note

The cryoprobe device is commonly used by orbital surgeons for the extraction of intraorbital lesions. Cryoprobes provide a safe mechanism to manipulate fluid-filled tumors. Such lesions can present in locations in which intraoperative neurosurgical assistance is essential. The authors describe a technique whereby removal of an orbital hemangioma was facilitated by the aid of an endoscopic, transnasal cryoprobe while standard microsurgical dissection was performed concurrently via a transconjunctival approach.

Temperature Gradients and Residual Porosity in Microwave Sintered Zinc Oxide

ZnO samples were sintered in an overmoded 2.45 GHz microwave applicator. In-situ differential temperature measurements were made to allow comparison of surface and core temperatures during heating. At intermediate temperatures, near 600°C, the sample core was measured to be more than 250°C hotter than the sample surface. As the core temperature approached 1100°C, however, the difference between the surface and core temperatures diminished. Post-sintering scanning electron microscopy (SEM) showed spatial variations in the residual porosity which were consistent with the measured temperature differential. For samples sintered to intermediate temperatures, where large temperature differences persisted, there were significant gradients in the residual porosity. For samples sintered to higher temperatures, there was little residual porosity and no observable porosity gradient. Local density versus temperature behavior was obtained by correlating porosity levels measured from the micrographs with temperature measurements made during sintering. These data demonstrate a significantly lower activation energy for microwave sintering than for conventional sintering.

Observation of ultrahigh-energy cosmic rays with the ANITA balloon-borne radio interferometer

We report the observation of 16 cosmic ray events with a mean energy of 1.5 × 10¹⁹ eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300-900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models. The emission is 100% polarized in the plane perpendicular to the projected geomagnetic field. Fourteen events are seen to have a phase inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon. Based on a likelihood analysis, we estimate angular pointing precision of order 2° for the event arrival directions.