Abstract P1-01-02: Quantitative breast MRI to predict response to neoadjuvant therapy in community imaging centers: Preliminary results

Introduction: Early response assessment to neoadjuvant therapy (NAT) for locally advanced breast cancer would allow for more accurate prognosis and provide the opportunity to replace an ineffective treatment with an alternative regimen. This could potentially increase systemic treatment efficacy and avoid unnecessary side effects from ineffective therapies. Quantitative MRI has been shown to be beneficial in predicting breast tumor response to treatment early during the course of NAT within many academic environments. Importantly, integrating quantitative imaging techniques into the community-based setting has the potential to reach a large percentage of breast cancer patients, as most patients receive their care at private practice or community hospitals. This study evaluated the ability to implement quantitative dynamic contrast enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI) data in the community setting to predict the eventual response of breast tumors to NAT.

Experimental Design: Women undergoing NAT for breast cancer (N=16) were scanned with DCE-MRI and DW-MRI at baseline (prior to beginning therapy, t1) and three longitudinal time points during the course of NAT to evaluate early response to therapy (t2, t3, t4). MRI was performed at two community imaging centers using a 3T Siemens Skyra scanners equipped with 8- or 16-channel breast coils. DW-MRI was acquired with a spin echo sequence with TR/TE = 3000/52 ms, b-values of 200, 800 s/mm2 and used to compute the apparent diffusion coefficient (ADC) values for every voxel. DCE-MRI data was collected (following a pre-contrast T1 map) with TR/TE/α = 7.02 ms/4.60 ms/6o, and a temporal resolution of 7.27 sec for eight minutes. A catheter placed within an antecubital vein delivered gadolinium-based contrast agent (0.1 mmol/kg of Multihance or 10 mL of Gadovist) at 2 mL/sec via a power injector after the acquisition of the first minute of dynamic scans (baseline).Quantitative measures of ADC (evaluating cellularity from DW-MRI) and Ktrans(evaluating vascular perfusion and permeability from DCE-MRI) were calculated for the segmented tumor volume. Imaging was compared to pathology reports at the conclusion of NAT.

Results:The patients (n = 6) achieving a pathological complete response (pCR) revealed a 12.9% ± 19.1% increase in the mean ADC values of the tumor from t1 and t2. Conversely, patients (n = 10) that had residual disease burden after NAT (i.e., a non-pCR) had a decreased ADC, revealing a -8.0% ± 19.2% change between t1 and t2 (p = 0.06). The mean Ktrans values of the tumor decreased showing a change of -61.4% ± 18.2% from t1 to t2 in the pCR patients. Conversely, non-pCR patients had a 10.2% ± 80.4% increase in Ktrans between t1 and t2 (p = 0.14)

Conclusion:Preliminary evidence reveals that quantitative DCE-MRI and DW-MRI can be implemented in community-based imaging settings to predict the response of breast tumors to NAT. Thus, our results provide evidence that quantitative DW-MRI and DCE-MRI can be disseminated across community imaging facilities, thereby dramatically increasing the patient population for which these techniques can serve.

We acknowledge the support of CPRIT RR160005.

Citation Format: Sorace AG, Virostko J, Wu C, Jarrett AM, Barnes SL, Ekrut D, Patt D, Goodgame B, Avery S, Yankeelov TE. Quantitative breast MRI to predict response to neoadjuvant therapy in community imaging centers: Preliminary results [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-01-02.

A transfusion prescription template and other human factor interventions to improve balanced transfusion delivery in major haemorrhage due to trauma

OBJECTIVES

The aim of this study is to improve practice in the management of major haemorrhage, particularly in red cell to plasma transfusion ratios.

BACKGROUND

A review of the management of major haemorrhage in trauma in Newcastle Hospitals Trust in 2012-2013 showed good mortality outcomes but found that red cell : plasma transfusion ratios could be improved. Human factors techniques transferable from industry and the military were identified, and a package of interventions was implemented, including an intensive multidisciplinary team training programme and a new major haemorrhage prescription template.

METHODS/MATERIALS

We reviewed the management of all 243 adult trauma patients admitted with major haemorrhage to the Emergency Department in the Newcastle Hospitals Trust in the 4-year period from April 2012. We analysed clinical details, blood components transfused and patient outcomes and used Trauma Audit and Research Network data to correlate with injury severity and predicted survival.

RESULTS

Mean transfusion ratios of red cells to plasma improved from 1·5 : 1 and 1·6 : 1 in the first 2 years to 1·1 : 1 in the 2 years following implementation of the new measures. There was a statistically significant improvement in the delivery of a balanced transfusion, defined as a red cell : plasma ratio of <1·3 : 1 following the changes.

CONCLUSION

Simple changes to procedures, specifically implementation of a new major haemorrhage prescription template and multidisciplinary team training, have resulted in marked improvement in the ratio of red cells to plasma transfused to trauma patients with major haemorrhage or requiring emergency blood. The package of changes could be easily replicated in other health-care settings.

3D prompt gamma imaging for proton beam range verification

We tested the ability of a single Compton camera (CC) to produce 3-dimensional (3D) images of prompt gammas (PGs) emitted during the irradiation of a tissue-equivalent plastic phantom with proton pencil beams for clinical doses delivered at clinical dose rates. PG measurements were made with a small prototype CC placed at three different locations along the proton beam path. We evaluated the ability of the CC to produce images at each location for two clinical scenarios: (1) the delivery of a single 2 Gy pencil beam from a hypo-fractionated treatment (~9  ×  10⁸ protons), and (2) a single pencil beam from a standard treatment (~1  ×  10⁸ protons). Additionally, the data measured at each location were combined to simulate measurements with a larger scale, clinical CC and its ability to image shifts in the Bragg peak (BP) range for both clinical scenarios. With our prototype CC, the location of the distal end of the BP could be seen with the CC placed up to 4 cm proximal or distal to the BP distal falloff. Using the data from the simulated full scale clinical CC, 3D images of the PG emission were produced with the delivery of as few as 1  ×  10⁸ protons, and shifts in the proton beam range as small as 2 mm could be detected for delivery of a 2 Gy spot. From these results we conclude that 3D PG imaging for proton range verification under clinical beam delivery conditions is possible with a single CC.

Organising pneumonia due to dronedarone

Organising pneumonia is one of the responses of the lung to injury and can mimic bacterial pneumonia but importantly it does not respond to antibiotic therapy. We present the case of a 67-year-old male who was diagnosed with organising pneumonia secondary to dronedarone. Drug reactions are a common cause and early identification of the culprit is mandatory to prevent further morbidity and ensure a favourable outcome. On chest radiography there may be fleeting peripheral consolidation, while computed tomography can show a range of stereotyped patterns including perilobular consolidation. Bronchoscopic biopsy may not always be possible but response to steroids is often rapid following removal of the culprit drug. Dronedarone should be included in the list of possible drugs and the Pneumotox database remains a useful resource for the clinician when acute drug-related pneumotoxicity is suspected.

Proton beam characterization by proton-induced acoustic emission: simulation studies

Due to their Bragg peak, proton beams are capable of delivering a targeted dose of radiation to a narrow volume, but range uncertainties currently limit their accuracy. One promising beam characterization technique, protoacoustic range verification, measures the acoustic emission generated by the proton beam. We simulated the pressure waves generated by proton radiation passing through water. We observed that the proton-induced acoustic signal consists of two peaks, labeled α and γ, with two originating sources. The α acoustic peak is generated by the pre-Bragg peak heated region whereas the source of the γ acoustic peak is the proton Bragg peak. The arrival time of the α and γ peaks at a transducer reveals the distance from the beam propagation axis and Bragg peak center, respectively. The maximum pressure is not observed directly above the Bragg peak due to interference of the acoustic signals. Range verification based on the arrival times is shown to be more effective than determining the Bragg peak position based on pressure amplitudes. The temporal width of the α and γ peaks are linearly proportional to the beam diameter and Bragg peak width, respectively. The temporal separation between compression and rarefaction peaks is proportional to the spill time width. The pressure wave expected from a spread out Bragg peak dose is characterized. The simulations also show that acoustic monitoring can verify the proton beam dose distribution and range by characterizing the Bragg peak position to within ~1 mm.

Separated response function ratios in exclusive, forward π(±) electroproduction

The study of exclusive π(±) electroproduction on the nucleon, including separation of the various structure functions, is of interest for a number of reasons. The ratio RL=σL(π-)/σL(π+) is sensitive to isoscalar contamination to the dominant isovector pion exchange amplitude, which is the basis for the determination of the charged pion form factor from electroproduction data. A change in the value of RT=σT(π-)/σT(π+) from unity at small -t, to 1/4 at large -t, would suggest a transition from coupling to a (virtual) pion to coupling to individual quarks. Furthermore, the mentioned ratios may show an earlier approach to perturbative QCD than the individual cross sections. We have performed the first complete separation of the four unpolarized electromagnetic structure functions above the dominant resonances in forward, exclusive π(±) electroproduction on the deuteron at central Q(2) values of 0.6, 1.0, 1.6  GeV(2) at W=1.95  GeV, and Q(2)=2.45  GeV(2) at W=2.22  GeV. Here, we present the L and T cross sections, with emphasis on RL and RT, and compare them with theoretical calculations. Results for the separated ratio RL indicate dominance of the pion-pole diagram at low -t, while results for RT are consistent with a transition between pion knockout and quark knockout mechanisms.

BCL-XL mediates the strong selective advantage of a 20q11.21 amplification commonly found in human embryonic stem cell cultures

Human embryonic stem cells (hESCs) regularly acquire nonrandom genomic aberrations during culture, raising concerns about their safe therapeutic application. The International Stem Cell Initiative identified a copy number variant (CNV) amplification of chromosome 20q11.21 in 25% of hESC lines displaying a normal karyotype. By comparing four cell lines paired for the presence or absence of this CNV, we show that those containing this amplicon have higher population doubling rates, attributable to enhanced cell survival through resistance to apoptosis. Of the three genes encoded within the minimal amplicon and expressed in hESCs, only overexpression of BCL2L1 (BCL-XL isoform) provides control cells with growth characteristics similar to those of CNV-containing cells, whereas inhibition of BCL-XL suppresses the growth advantage of CNV cells, establishing BCL2L1 as a driver mutation. Amplification of the 20q11.21 region is also detectable in human embryonal carcinoma cell lines and some teratocarcinomas, linking this mutation with malignant transformation.

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The presence of the 20q11.21 CNV protects hESCs against apoptosis

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20q11.21 CNV cells have increased levels of antiapoptotic BCL-XL, driving selection

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hECCs and primary embryonal carcinoma samples also display the 20q11.21 CNV

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20q11.21 CNV could be a feature of neoplastic progression

SU-E-T-266: Shielding Measurements for a Proton Therapy Facility

PURPOSE

This paper is a follow up on the analytical calculations for the Roberts Proton Therapy Center with empirical data to determine the precision of the calculations from Avery, et al.

METHODS

Neutrak dosimeters were placed in two sets around the facility while it was in operation at points of interest examined in Avery, et al. The doses to these dosimeters were recorded over one month for one set and two months for the other. Dosimeters that both recorded a dose and could be practically examined were compared to the doses predicted via the analytical method of Avery, et al. at their point of placement.

RESULTS

Two points showed a less than 10% difference to the calculated doses. One point shielded by both concrete and pre-cast blocks and one point shielded by both concrete and the facility's cyclotron were not as precise.

CONCLUSIONS

The analytical calculation method explored in Avery, et al. is fairly precise in describing the dose at various points in the facility shielded only by concrete. for materials other than concrete, such as the make-up of the cyclotron or varying wall material, it warrants follow up calculations using the same method.

Selective FLT3 inhibition of FLT3-ITD+ acute myeloid leukaemia resulting in secondary D835Y mutation: a model for emerging clinical resistance patterns

Acquired resistance to selective FLT3 inhibitors, is an emerging clinical problem in the treatment of FLT3-ITD⁺ acute myeloid leukaemia (AML). The paucity of valid pre-clinical models has limited investigations to determine the mechanism of acquired therapeutic resistance, thereby limiting the development of effective treatments. We generated selective FLT3 inhibitor-resistant cells by treating the FLT3-ITD⁺ human AML cell line MOLM-13 in vitro with the FLT3-selective inhibitor MLN518, and validated the resistant phenotype in vivo and in vitro. The resistant cells, MOLM-13-RES, harboured a new D835Y tyrosine kinase domain (TKD) mutation on the FLT3-ITD⁺ allele. Acquired TKD mutations, including D835Y, have recently been identified in FLT3-ITD⁺ patients relapsing after treatment with the novel FLT3 inhibitor, AC220. Consistent with this clinical pattern of resistance, MOLM-13- RES cells displayed high relative resistance to AC220 and Sorafenib. Furthermore, treatment of MOLM-13-RES cells with AC220 lead to loss of the FLT3 wild type allele and duplication of the FLT3-ITD-D835Y allele. Our FLT3-Aurora kinase inhibitor, CCT137690, successfully inhibited growth of FLT3-ITD-D835Y cells in vitro and in vivo, suggesting that dual FLT3-Aurora inhibition may overcome selective FLT3 inhibitor resistance, in part due to inhibition of Aurora kinase, and may benefit patients with FLT3-mutated AML.

Generation of inducible shRNAi human embryonic stem cell lines

This unit describes the generation of tetracycline-inducible short hairpin RNA interference (shRNAi) human embryonic stem cell (hESC) lines. Using this vector-based approach enables stable and long-term expression of target hairpins under the control of doxycycline/tetracycline. Target degradation can be controlled in both a dose- and time-dependent manner that can even be switched off, depending upon the particular requirements of the study.

Screening ethnically diverse human embryonic stem cells identifies a chromosome 20 minimal amplicon conferring growth advantage

The International Stem Cell Initiative analyzed 125 human embryonic stem (ES) cell lines and 11 induced pluripotent stem (iPS) cell lines, from 38 laboratories worldwide, for genetic changes occurring during culture. Most lines were analyzed at an early and late passage. Single-nucleotide polymorphism (SNP) analysis revealed that they included representatives of most major ethnic groups. Most lines remained karyotypically normal, but there was a progressive tendency to acquire changes on prolonged culture, commonly affecting chromosomes 1, 12, 17 and 20. DNA methylation patterns changed haphazardly with no link to time in culture. Structural variants, determined from the SNP arrays, also appeared sporadically. No common variants related to culture were observed on chromosomes 1, 12 and 17, but a minimal amplicon in chromosome 20q11.21, including three genes expressed in human ES cells, ID1, BCL2L1 and HM13, occurred in >20% of the lines. Of these genes, BCL2L1 is a strong candidate for driving culture adaptation of ES cells.

Abstract LB-245: Loss of function of the TGFβRI receptor leads to the spontaneously regressing squamous carcinoma condition, multiple self-healing squamous epithelioma (Ferguson-Smith disease)

A re-examination has been carried out of the region on chromosome 9 containing the locus responsible for Ferguson-Smith disease, or multiple self-healing squamous epithelioma (MSSE/FSD); this is a rare autosomal dominant inherited condition first identified in the west of Scotland, that presents with multiple squamous cell skin carcinomas which grow, invade locally and then spontaneously regress.

Approach: A 4Mb locus on chromosome 9 was earlier identified by genetic mapping in a cluster of families. In this study a wider region encompassing 24Mb around this earlier identified locus was examined using high-throughput sequencing with exon capture, followed by Sanger sequencing.

Result: This effort identified mutations in the TGFBR1 gene in 18 out of 22 families diagnosed as affected by MSSE/FSD. These include 11 different mutations. The tumours occur in sun-exposed areas of the skin, and loss-of-heterozygosity in tumours is frequently seen. The sequence variants disturb the function of the TGFβRI receptor such that although heterozygous carriers are asymptomatic during development, loss of the second (wild-type) allele ablates the receptor function and leads to local cancer susceptibility.

Conclusions: The nature of the mutations sets the mechanism apart from that involved in Marfan syndrome-related disorders, in which developmental defects in vasculature are also caused by mutations in this gene. The involvement of TGFβ receptors in this condition is intriguing as TGFβ pathway effects are known to be biphasic and opposing at different stages of cancer development.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-245. doi:10.1158/1538-7445.AM2011-LB-245

Effects of proton radiation dose, dose rate and dose fractionation on hematopoietic cells in mice

The present study evaluated the acute effects of radiation dose, dose rate and fractionation as well as the energy of protons in hematopoietic cells of irradiated mice. The mice were irradiated with a single dose of 51.24 MeV protons at a dose of 2 Gy and a dose rate of 0.05-0.07 Gy/min or 1 GeV protons at doses of 0.1, 0.2, 0.5, 1, 1.5 and 2 Gy delivered in a single dose at dose rates of 0.05 or 0.5 Gy/min or in five daily dose fractions at a dose rate of 0.05 Gy/min. Sham-irradiated animals were used as controls. The results demonstrate a dose-dependent loss of white blood cells (WBCs) and lymphocytes by up to 61% and 72%, respectively, in mice irradiated with protons at doses up to 2 Gy. The results also demonstrate that the dose rate, fractionation pattern and energy of the proton radiation did not have significant effects on WBC and lymphocyte counts in the irradiated animals. These results suggest that the acute effects of proton radiation on WBC and lymphocyte counts are determined mainly by the radiation dose, with very little contribution from the dose rate (over the range of dose rates evaluated), fractionation and energy of the protons.