Characterization and Applications of Permeabilized Hepatocytes in Drug Discovery

Hepatocytes are one of the most physiologically relevant in vitro liver systems for human translation of clearance and drug-drug interactions (DDI). However, the cell membranes of hepatocytes can limit the entry of certain compounds into the cells for metabolism and DDI. Passive permeability through hepatocytes can be different in vitro and in vivo, which complicates the human translation. Permeabilized hepatocytes offer a useful tool to probe mechanistic understanding of permeability-limited metabolism and DDI. Incubation with saponin of 0.01% at 0.5 million cells/mL and 0.05% at 5 million cells/mL for 5 min at 37°C completely permeabilized the plasma membrane of hepatocytes, while leaving the membranes of subcellular organelles intact. Permeabilized hepatocytes maintained similar enzymatic activity as intact unpermeabilized hepatocytes and can be stored at -80°C for at least 7 months. This approach reduces costs by preserving leftover hepatocytes. The relatively low levels of saponin in permeabilized hepatocytes had no significant impact on the enzymatic activity. As the cytosolic contents leak out from permeabilized hepatocytes, cofactors need to be added to enable metabolic reactions. Cytosolic enzymes will no longer be present if the media are removed after cells are permeabilized. Hence permeabilized hepatocytes with and without media removal may potentially enable reaction phenotyping of cytosolic enzymes. Although permeabilized hepatocytes work similarly as human liver microsomes and S9 fractions experimentally requiring addition of cofactors, they behave more like hepatocytes maintaining enzymatic activities for over 4 h. Permeabilized hepatocytes are a great addition to the drug metabolism toolbox to provide mechanistic insights.

Novel Multiplexed High Throughput Screening of Selective Inhibitors for Drug-Metabolizing Enzymes Using Human Hepatocytes

Selective chemical inhibitors are critical for reaction phenotyping to identify drug-metabolizing enzymes that are involved in the elimination of drug candidates. Although relatively selective inhibitors are available for the major cytochrome P450 enzymes (CYP), they are quite limited for the less common CYPs and non-CYPs. To address this gap, we developed a multiplexed high throughput screening (HTS) assay using 20 substrate reactions of multiple enzymes to simultaneously monitor the inhibition of enzymes in a 384-well format. Four 384-well assay plates can be run at the same time to maximize throughput. This is the first multiplexed HTS assay for drug-metabolizing enzymes reported. The HTS assay is technologically enabled with state-of-the-art robotic systems and highly sensitive modern LC-MS/MS instrumentation. Virtual screening is utilized to identify inhibitors for HTS based on known inhibitors and enzyme structures. Screening of ~4600 compounds generated many hits for many drug-metabolizing enzymes including the two time-dependent and selective aldehyde oxidase inhibitors, erlotinib and dibenzothiophene. The hit rate is much higher than that for the traditional HTS for biological targets due to the promiscuous nature of the drug-metabolizing enzymes and the biased compound selection process. Future efforts will focus on using this method to identify selective inhibitors for enzymes that do not currently have quality hits and thoroughly characterizing the newly identified selective inhibitors from our screen. We encourage colleagues from other organizations to explore their proprietary libraries using a similar approach to identify better inhibitors that can be used across the industry.

Comparison of Tumor Binding Across Tumor Types and Cell Lines to Support Free Drug Considerations for Oncology Drug Discovery

Tumor binding is an important parameter to derive unbound tumor concentration to explore pharmacokinetics (PK) and pharmacodynamics (PD) relationships for oncology disease targets. Tumor binding was evaluated using eleven matrices, including various commonly used ex vivo human and mouse xenograft and syngeneic tumors, tumor cell lines and liver as a surrogate tissue. The results showed that tumor binding is highly correlated among the different tumors and tumor cell lines except for the mouse melanoma (B16F10) tumor type. Liver fraction unbound (fu) has a good correlation with B16F10 tumor binding. Liver also demonstrates a two-fold equivalency, on average, with binding of other tumor types when a scaling factor is applied. Predictive models were developed for tumor binding, with correlations established with LogD (acids), predicted muscle fu (neutrals) and measured plasma protein binding (bases) to estimate tumor fu when experimental data are not available. Many approaches can be applied to obtain and estimate tumor binding values. One strategy proposed is to use a surrogate tumor tissue, such as mouse xenograft ovarian cancer (OVCAR3) tumor, as a surrogate for tumor binding (except for B16F10) to provide an early assessment of unbound tumor concentrations for development of PK/PD relationships.

An evaluation of a healthy participant laboratory model of epidural hyperthermia: a physiological study

BACKGROUND

Hyperthermia complicates 21% of cases of intrapartum epidural analgesia, but the mechanism is unclear. One hypothesis is that blockade of cholinergic sympathetic nerves prevents active vasodilation and sweating, thus limiting heat loss. Because labour increases heat production, this could create a situation in which heat production exceeds loss, causing body temperature to rise. This physiological study tested a novel laboratory model of epidural-related hyperthermia, using exercise to simulate the increased heat production of labour and surface insulation to simulate the effect of epidural analgesia.

METHODS

Twelve healthy non-pregnant participants (six female) cycled an ergometer for two hours at 20 Watts (W) on two occasions: once with surface insulation (intervention) and once without (control). Core temperature, skin temperature (eight sites), and heat loss (eight sites) were recorded. Mean body temperature and heat production were calculated. Values are mean (SD).

RESULTS

Exercise increased heat production on both visits (intervention 38 (18) W; control 37 (31) W; P = 0.94). Total heat loss was less on the intervention visit (intervention 115 (19) W; control 129 (23) W; P = 0.002). Core temperature increased on both visits (intervention 0.21 (0.37)°C; control 0.19 (0.27)°C; P < 0.001). The increase in mean body temperature was greater on the intervention visit (intervention 0.47 (0.41)°C; control 0.25 (0.19)°C; P = 0.007).

CONCLUSIONS

This laboratory model predicts that labour epidural analgesia limits heat loss by >14 W. Once the model is validated, it could be used to test the efficacy of potential interventions to prevent and treat epidural-related maternal hyperthermia.

The Comparison of Machine Learning and Mechanistic In Vitro-In Vivo Extrapolation Models for the Prediction of Human Intrinsic Clearance

Accurate prediction of human pharmacokinetics (PK) remains one of the key objectives of drug metabolism and PK (DMPK) scientists in drug discovery projects. This is typically performed by using in vitro-in vivo extrapolation (IVIVE) based on mechanistic PK models. In recent years, machine learning (ML), with its ability to harness patterns from previous outcomes to predict future events, has gained increased popularity in application to absorption, distribution, metabolism, and excretion (ADME) sciences. This study compares the performance of various ML and mechanistic models for the prediction of human IV clearance for a large (645) set of diverse compounds with literature human IV PK data, as well as measured relevant in vitro end points. ML models were built using multiple approaches for the descriptors: (1) calculated physical properties and structural descriptors based on chemical structure alone (classical QSAR/QSPR); (2) in vitro measured inputs only with no structure-based descriptors (ML IVIVE); and (3) in silico ML IVIVE using in silico model predictions for the in vitro inputs. For the mechanistic models, well-stirred and parallel-tube liver models were considered with and without the use of empirical scaling factors and with and without renal clearance. The best ML model for the prediction of in vivo human intrinsic clearance (CLint) was an in vitro ML IVIVE model using only six in vitro inputs with an average absolute fold error (AAFE) of 2.5. The best mechanistic model used the parallel-tube liver model, with empirical scaling factors resulting in an AAFE of 2.8. The corresponding mechanistic model with full in silico inputs achieved an AAFE of 3.3. These relative performances of the models were confirmed with the prediction of 16 Pfizer drug candidates that were not part of the original data set. Results show that ML IVIVE models are comparable to or superior to their best mechanistic counterparts. We also show that ML IVIVE models can be used to derive insights into factors for the improvement of mechanistic PK prediction.

Salvage Abdominoperineal Resection for Locally Recurrent or Persistent Anal Squamous Cell Carcinoma after Definitive Chemoradiation

PURPOSE/OBJECTIVE(S)

Initial treatment for patients with squamous cell carcinoma of the anal canal includes definitive chemoradiation. Salvage abdominoperineal resection (APR) is the treatment of choice for recurrent or persistent disease. Older studies suggest approximately 50% successful salvage of recurrent or persistent disease with APR. Risk factors for failure after salvage APR are incompletely characterized.

MATERIALS/METHODS

Using a single institutional database, patients were identified who underwent salvage APR after definitive intensity-modulated radiotherapy-based chemoradiation between 2003 and 2022. Clinical and pathologic variables analyzed included age at APR, sex, race, HIV status, initial cT stage, initial cN stage, radiation dose, recurrent vs persistent disease, recurrent pT stage, recurrent pN stage, the presence of LVSI, PNI or <2mm surgical margins, and the use of either intraoperative radiation or another treatment modality in addition to APR. The log rank test was used to determine differences in time from APR to events (local recurrence, distant metastasis and death) based on clinical and pathologic variables. The Cox Proportional Hazard Model was used to perform multivariable analysis for all factors with a univariate P-value <0.1.

RESULTS

Of 628 patients with anal squamous cell carcinoma, 50 (8.0%) were treated with abdominoperineal resection for locally recurrent (n = 29, 58%) or locally persistent (n = 21, 42%) disease. Median [interquartile range] follow up was 40.0 months [15.2-68.0 months] from APR. Median local recurrence-free survival was not reached; 1- and 2-year local recurrence-free survival was 81% (95% CI 72-92%) and 76% (64-89%). On multivariable analysis, pathologic T-stage of the recurrence (3.85 (1.07-13.9); P = .040), the presence of lymphovascular space invasion (9.1 (1.12-73.62); P = .038) and surgical margins <2mm (8.81 (2.11-36.73); P = .003) were all significantly associated with higher rates of local recurrence. Median distant metastasis-free survival was not reached; 1- and 2-year distant metastasis-free survival was 88% (81-98%) and 79% (67-92%). On multivariable analysis, only persistent (versus recurrent) local disease was significantly associated with higher rates of distant metastasis (1.23 (1.05-5.55) P = .043). Median overall survival was not reached; 1- and 2-year overall survival was 90% (81-98%) and 78% (65-90%). On multivariable analysis, only recurrent pT stage (T3/4 vs T1/2) was associated with higher rates of death (5.87 (1.02-33.65); P = .047).

CONCLUSION

APR is a successful salvage modality for anal squamous cell carcinoma with recurrent or persistent disease after chemoradiation results. Patients with pT3/4 disease, lymphovascular space invasion, surgical margins <2 mm may be associated with higher re-recurrence rates and may benefit from more frequent monitoring or treatment escalation.

Predictors of Low Anterior Resection Syndrome after Long-Course Chemoradiation for Locally Advanced Rectal Cancer

PURPOSE/OBJECTIVE(S)

Low anterior resection syndrome (LARS) describes disordered bowel function including tenesmus, frequent, clustered, incomplete, urgent or incontinent bowel movements. The impact of clinical and radiation dosimetric factors on LARS score is unknown. We aimed to evaluate the radiation plans for patients who received long course chemoradiation (LC-CRT) to identify potential dosimetric predictors of LARS.

MATERIALS/METHODS

We identified patients with rectal cancer treated with LC-CRT (50.4Gy in 28 fractions) at our institution from 2016-2020 who were alive and without disease. As a part of a larger patient-reported outcome survey, we obtained the Low Anterior Resection Syndrome Score (LARS) for patients without an ostomy at the time of the survey. We utilized clinical and dosimetric variables in a multivariate analysis including age at LC-CRT, body mass index, sex, distance of the tumor from the anal verge (AV), threatened mesorectal fascia (MRF) on staging imaging, T-stage, N-stage, receipt of surgery (vs non-operative management (NOM), radiation technique (3DCRT vs VMAT), mean dose and D0.03ccs for the anal canal (defined as 4cm from the anal verge) and D0.03cc, V30Gy and V45Gy for the small bowel loops. We then created a multiple linear regression model to predict LARS using P>.20 on univariate testing.

RESULTS

Of 110 patients treated with preoperative LC-CRT and who did not have an ostomy, 57 responded (51.8%). The median [interquartile range (IQR)] interval from completion of LC-CRT to survey completion was 38.4 months [26.3-48.9]. Thirty-four patients (60%) were men, the median [IQR] BMI was 28 [24-31.9], the median [IQR] distance of the tumor to the anal verge was 7cm [5-10], 40 (70%) had T3 tumors, 7 (12%) had T4 tumors, 45 (79%) were N+. Forty-one patients (72%) had surgery following LC-CRT, and 16 (28%) had non-operative management. 3D conformal technique was used for 47 (82%) and VMAT used for 10 patients (18%). The median [IQR] LARS score was 32 [24-38] with 35 patients (61%) classified as Major LARS (LARS score = 30-42). On multiple linear regression modeling (Table), only receipt of surgery significantly predicted for higher (worse) LARS score.

CONCLUSION

In our cohort, patients who received surgery after LC-CRT had a significantly higher LARS score. Of the dosimetric parameters tested, D0.03ccs was the best predictor and could potentially be significant with a larger number of patients. Further work is needed to improve bowel function and quality of life for patients treated with LC-CRT for rectal adenocarcinoma.

Outcomes and after Hyperfractionated, Accelerated Reirradiation for Recurrent Anal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

Abdominoperineal resection (APR) is the standard salvage treatment for recurrent or persistent squamous cell carcinoma of the anus (SCCA). However, reirradiation (reRT) can be used preoperatively or for those who are not candidates for surgery.

MATERIALS/METHODS

Using a single institutional database, patients were identified who underwent reRT for SCCA from 2003 to 2022. Response to reRT and outcomes after reRT were recorded. Variables analyzed included age at reRT, sex, reason for reRT (recurrent SCCA vs new SCCA after pelvic radiation for a different malignancy), interval between initial radiation and reRT, reRT dose, concurrent chemotherapy, receipt of APR and the presence of distant metastases at the time of reRT. Cox Proportional Hazard Model was used; multivariable analysis for all factors with a univariate P-value <0.1 on univariable analysis.

RESULTS

A total of 42 patients received reRT, which consisted of 1.5 Gray (Gy) twice daily fractions with ≥6-hour interval to a total dose ranging 30Gy to 54Gy (median [IQR] 39Gy [39-42Gy]. Thirty-eight patients (90.5%) received concurrent chemotherapy; most often with weekly cisplatin and 5-fluorouracil (N = 23, 54.8%). Median [IQR] follow-up after reRT was 11.4 months [4.9-40.8 months]. Median [IQR] initial radiation dose was 54Gy [54-58Gy], and median [IQR] interval between initial radiation and reRT was 3.6 years [2.1-6.0 years]. For 8 patients (19.1%), the initial radiation was given for a different pelvic malignancy prior to being diagnosed with SCCA. Four of these patients received brachytherapy alone or in conjunction with external beam. For the remaining 34 patients, the initial radiation was for SCCA and the reRT was for recurrent SCCA either in the anal canal (N = 23, 67.6%) or regional nodes (N = 11, 32.3%). Four patients (9.5%) had distant disease at the time of reRT. Eleven patients (26.2%) had planned APR after preoperative reRT; 1 patient had a pathologic complete response (pCR), 2 patients had a near pCR (<5% viable cancer). Twenty-nine patients (69.0%) were treated with reRT alone; 15 (51.7%) attained a clinical CR. Two patients (4.8%) were treated with palliative intent and response was not assessed. Median local recurrence free survival (LRFS) was 9.9 months; 2- and 3-year LRFS were both 41%. Median distant metastasis free survival (DMFS) was 11.8 months; 2- and 3-year DMFS were 38% and 34%, respectively. Median overall survival (OS) was 40.5 months; 2- and 3-year OS were 54% and 51%, respectively. On multivariable analysis, only the presence of distant disease at the time of reRT was significantly associated with worse LRFS (HR (95% CI) 4.14 (1.34-12.81); P = .014), worse DMFS (4.06 (1.37-12.06); P = .012) and worse OS (5.73 (1.57-20.9); P = .008).

CONCLUSION

ReRT is an option for patients presenting with either recurrent SCCA or new SCCA after prior pelvic radiation for a different malignancy. ReRT can be given prior to planned salvage APR or alone for patients who are not surgical candidates with an approximate 50% cCR rate.

Patient-Reported Outcomes During and After Treatment for Locally Advanced Rectal Cancer in the PROSPECT Trial (Alliance N1048)

PURPOSE

The standard of care for locally advanced rectal cancer in North America is neoadjuvant pelvic chemoradiation with fluorouracil (5FUCRT). Neoadjuvant chemotherapy with fluorouracil and oxaliplatin (FOLFOX) is an alternative that may spare patients the morbidity of radiation. Understanding the relative patient experiences with these options is necessary to inform treatment decisions.

METHODS

PROSPECT was a multicenter, unblinded, noninferiority, randomized trial of neoadjuvant FOLFOX versus 5FUCRT, which enrolled adults with rectal cancer clinically staged as T2N+, cT3N-, or cT3N+ who were candidates for sphincter-sparing surgery. Neoadjuvant FOLFOX was given in six cycles over 12 weeks, followed by surgery. Neoadjuvant 5FUCRT was delivered in 28 fractions over 5.5 weeks, followed by surgery. Adjuvant chemotherapy was suggested but not mandated in both groups. Enrolled patients were asked to provide patient-reported outcomes (PROs) at baseline, during neoadjuvant treatment, and at 12 months after surgery. PROs included 14 symptoms from the National Cancer Institute's Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE). Additional PRO instruments measured bowel, bladder, sexual function, and health-related quality of life (HRQL).

RESULTS

From June 2012 to December 2018, 1,194 patients were randomly assigned, 1,128 initiated treatment, and 940 contributed PRO-CTCAE data (493 FOLFOX; 447 5FUCRT). During neoadjuvant treatment, patients reported significantly lower rates of diarrhea and better overall bowel function with FOLFOX while anxiety, appetite loss, constipation, depression, dysphagia, dyspnea, edema, fatigue, mucositis, nausea, neuropathy, and vomiting were lower with 5FUCRT (all multiplicity adjusted P < .05). At 12 months after surgery, patients randomly assigned to FOLFOX reported significantly lower rates of fatigue and neuropathy and better sexual function versus 5FUCRT (all multiplicity adjusted P < .05). Neither bladder function nor HRQL differed between groups at any time point.

CONCLUSION

For patients with locally advanced rectal cancer choosing between neoadjuvant FOLFOX and 5FUCRT, the distinctive PRO profiles inform treatment selection and shared decision making.

Effect of Low Protein Diet Supplemented with Ketoanalogs on Endothelial Function and Protein-Bound Uremic Toxins in Patients with Chronic Kidney Disease

Studies have demonstrated that a low-protein diet supplemented with ketoanalogs (KAs) could significantly retard progression of renal function in patients with chronic kidney disease (CKD) stages 3-5. However, its effects on endothelial function and serum levels of protein-bound uremic toxins remain elusive. Therefore, this study explored whether a low-protein diet (LPD) supplemented with KAs affects kidney function, endothelial function, and serum uremic toxin levels in a CKD-based cohort. In this retrospective cohort, we enrolled 22 stable CKD stage 3b-4 patients on LPD (0.6-0.8 g/day). Patients were categorized into control (LPD only) and study groups (LPD + KAs 6 tab/day). Serum biochemistry, total/free indoxyl sulfate (TIS/FIS), total/free p-cresyl sulfate (TPCS/FPCS), and flow-mediated dilation (FMD) were measured before and after 6 months of KA supplementation. Before the trial, there were no significant differences in kidney function, FMD, or uremic toxin levels between the control and study groups. When compared with the control group, the paired t-test showed a significant decrease in TIS and FIS (all p < 0.05) and a significant increase in FMD, eGFR, and bicarbonate (all p < 0.05). In multivariate regression analysis, an increase in FMD (p < 0.001) and a decrease in FPCS (p = 0.012) and TIS (p < 0.001) remained persistent findings when adjusted for age, systolic blood pressure (SBP), sodium, albumin, and diastolic blood pressure (DBP). LPD supplemented with KAs significantly preserves kidney function and provides additional benefits on endothelial function and protein-bound uremic toxins in patients with CKD.

[High-fat intake alleviates lung injury induced by Paragonimus proliferus infection in rats through up-regulating CYP 4A1 expression in lung tissues]

OBJECTIVE

To explore the improvements of high-fat intake on lung injury induced by Paragonimus proliferus infection in rats, and to preliminarily explore the mechanisms underlying the role of cytochrome P450 4A1 (CYP 4A1) in the improve ments.

METHODS

SD rats were randomly assigned into three groups, including the normal control group (n = 10), the infection and normal diet group (n = 12) and the infection and high-fat diet group (n = 12). Rats in the normal control group were fed with normal diet and without any other treatments, and animals in the infection and normal diet group were subcutaneously injected with 8 excysted metacercariae of P. proliferus via the abdominal wall, followed by feeding with normal diet, while rats in the infection and high-fat diet group were subcutaneously injected with 8 excysted metacercariae of P. proliferus via the abdominal wall, followed by feeding with high-fat diet. All rats were sacrificed 28 weeks post-infection, and serum samples and lung specimens were collected. Following hematoxylin-eosin (HE) staining of rat lung specimens, the rat lung injury was observed under an optical microscope, and alveolitis was evaluated using semi-quantitative scoring. Serum interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) levels were measured using enzyme-linked immunosorbent assay (ELISA), and the cytochrome P450 4A1 (CYP 4A1) expression was quantified in rat lung specimens at transcriptional and translational levels using quantitative real-time PCR (qPCR) and Western blotting assays.

RESULTS

Alveolar wall thickening, edema and inflammatory cell infiltration were alleviated 28 weeks post-infection with P. proliferus in rats in the infection and high-fat diet group relative to the infection and normal diet group, and no alveolar consolidation was seen in the infection and high-fat diet group. The semi-quantitative score of alveolitis was significantly higher in the infection and normal diet group [(2.200 ± 0.289) points] than in the normal control group [(0.300 ± 0.083) points] and the infection and high-fat diet group [(1.300 ± 0.475) points] (both P values < 0.05), and higher serum IL-1β [(151.586 ± 20.492)] pg/mL and TNF-α levels [(180.207 ± 23.379) pg/mL] were detected in the infection and normal diet group than in the normal control group [IL-1β: (103.226 ± 3.366) pg/mL; TNF-α: (144.807 ± 1.348) pg/mL] and the infection and high-fat diet group [IL-1β: (110.131 ± 12.946) pg/mL; TNF-α: (131.764 ± 27.831) pg/mL] (all P values < 0.05). In addition, lower CYP 4A1 mRNA (3.00 ± 0.81) and protein expression (0.40 ± 0.02) was quantified in lung specimens in the infection and normal diet group than in the normal control group [(5.03 ± 2.05) and (0.84 ± 0.14)] and the infection and high-fat diet group [(11.19 ± 3.51) and (0.68 ± 0.18)] (all P values < 0.05).

CONCLUSIONS

High-fat intake may alleviate lung injuries caused by P. proliferus infection in rats through up-regulating CYP 4A1 expression in lung tissues at both translational and transcriptional levels.

Prostate sarcoma

Introduction

This report is intended to provide insight into the presentation, diagnosis, and treatment of prostatic sarcomas. A literature review is included to compare variables in demographics, histology, prognosis, and treatment strategies among previously reported incidences.

Case presentation

In this case, we have a 72-year-old man who initially presented with symptomatic nephrolithiasis that led to further workup. Magnetic resonance imaging revealed an enlarged, heterogeneous prostate with a dominant mass in the left lobe. A biopsy of the prostate revealed a high-grade, undifferentiated sarcoma in the left lobe along with concomitant adenocarcinoma in the right lobe.

Conclusions

The patient underwent a radical prostatectomy, which according to existing literature remains the most effective treatment strategy. Staging is the most important prognostic indicator, making this cancer particularly dangerous as presenting symptoms are highly variable among patients.

Patient-reported Bowel Function and Bowel-related Quality of Life After Pelvic Radiation for Rectal Adenocarcinoma: The Impact of Radiation Fractionation and Surgical Resection

INTRODUCTION

Multimodality treatment for locally advanced rectal cancer (LARC) can include long-course radiotherapy (LCRT) or short course radiotherapy (SCRT). Nonoperative management is increasingly pursued for those achieving a complete clinical response. Data regarding long-term function and quality-of-life (QOL) are limited.

METHODS

Patients with LARC treated with radiotherapy from 2016 to 2020 completed the Functional Assessment of Cancer Therapy- General (FACT-G7), the Low Anterior Resection Syndrome Score (LARS) and the Fecal Incontinence QOL Scale (FIQOL). Univariate and multivariable linear regression analyses identified associations between clinical variables including radiation fractionation and the use of surgery versus non-operative management.

RESULTS

Of 204 patients surveyed, 124 (60.8%) responded. Median (interquartile range) time from radiation to survey completion was 30.1 (18.3-43) months. Seventy-nine (63.7%) respondents received LCRT, and 45 (36.3%) received SCRT; 101 (81.5%) respondents underwent surgery, and 23 (18.5%) pursued nonoperative management. There were no differences in LARS, FIQoL or FACT-G7 between patients receiving LCRT versus SCRT. On multivariable analysis, only nonoperative management was associated with lower LARS score signifying less bowel dysfunction. Nonoperative management and female sex were associated with a higher FIQoL score signifying less disruption and distress from fecal incontinence issues. Finally, lower BMI at the time of radiation, female sex, and higher FIQoL score were associated with higher FACT-G7 scores signifying better overall QOL.

CONCLUSIONS

These results suggest long-term patient-reported bowel function and QOL may be similar for individuals receiving SCRT and LCRT for the treatment of LARC, but nonoperative management may lead to improved bowel function and QOL.

Abstract A077: PancreaCult™ Organoid Medium Kits support the robust establishment and expansion of human pancreatic duct organoids

Organoid culture is a novel in vitro culture method that promotes the growth of primary and PSC-derived cells in three-dimensional culture to generate structures that recapitulate tissue morphology. We have developed PancreaCult™ Organoid Medium Kits (Human), which combine PancreaCult™ Organoid Initiation Medium (OIM) and serum-free PancreaCult™ Organoid Growth Medium (OGM) into a robust and standardized workflow for the establishment and expansion of pancreatic duct organoids. To establish organoids, fresh or cryopreserved islet-depleted exocrine tissue was seeded in Corning® Matrigel® domes and cultured in PancreaCult™ OIM. After 3 days, the medium was changed to PancreaCult™ OGM and the organoids were passaged and maintained in this medium thereafter, and passaged as fragments every 4 - 7 days. Organoids were successfully established from all 5 donors with a 2- to 6-fold expansion in cell numbers every 7 - 14 days. Real-time PCR and immunocytochemistry demonstrated that these organoids express pancreatic duct markers (PDX1, SOX9, KRT19, CFTR, CA2, and MUC1), as well as proliferation and stem cell markers, Ki-67 and LGR5, respectively. Pancreatic duct organoids could be maintained for at least 10 passages (n = 3) and cryopreserved as fragments that could be used for rapid re-establishment of cultures at later time points. Organoids could also be dissociated and re-seeded in Prostaglandin E2-free PancreaCult™ OGM supplemented with ROCK inhibitor, Y-27632 and 10% FBS on Transwell® inserts to create 2D monolayers. In addition to normal pancreatic duct cultures, PancreaCult™ OGM supported the efficient long-term expansion of 4 pre-established pancreatic ductal adenocarcinoma (PDAC) organoid lines and maintained the mutational profile of the parent line after 5 passages, as determined through whole exome sequencing of 29 cancer-associated genes. Through the optional removal of epidermal growth factor (EGF), PancreaCult™ OGM can be modified to suppress normal cell growth to select for tumor cells with activating KRAS mutations. Our results demonstrate that PancreaCult™ Organoid Medium Kits provide a robust and flexible in vitro culture system for the establishment and expansion of normal pancreatic duct cells, as well as the long-term expansion of PDAC organoids.

Citation Format: Nina Quiskamp, Angela Tsai, Joanna Pan, Misha Hasan, George Chang, Isabella T. Tai, Allen C. Eaves, Sharon A. Louis, Ryan K. Conder. PancreaCult™ Organoid Medium Kits support the robust establishment and expansion of human pancreatic duct organoids [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A077.

Identification of Organic Anion Transporter 2 Inhibitors: Screening, Structure-Based Analysis, and Clinical Drug Interaction Risk Assessment

Organic anion transporter 2 (OAT2 or SLC22A7) plays an important role in the hepatic uptake and renal secretion of several endogenous compounds and drugs. The goal of this work is to understand the structure activity of OAT2 inhibition and assess clinical drug interaction risk. A single-point inhibition assay using OAT2-transfected HEK293 cells was employed to screen about 150 compounds; and concentration-dependent inhibition potency (IC₅₀) was measured for the identified "inhibitors". Acids represented about 65% of all inhibitors, and the frequency of bases-plus-zwitterions approximately doubled for "non-inhibitors". Interestingly, 9 of 10 most potent inhibitors (low IC₅₀) are acids (pK_a ∼ 3-5). Additionally, inhibitors are significantly larger and lipophilic than non-inhibitors. In silico (binary) models were developed to identify inhibitors and non-inhibitors. Finally, in vivo risk assessed via static drug-drug interaction models identified several inhibitors with potential for renal and hepatic OAT2 inhibition at clinical doses. This is the first study assessing the global pattern of OAT2-ligand interactions.

Effects of residual feed intake divergence on growth performance, carcass traits, meat quality, and blood biochemical parameters in small-sized meat ducks

Feed efficiency (FE) is a major economic trait of meat duck. This study aimed to evaluate the effects of residual feed intake (RFI) divergence on growth performance, carcass traits, meat quality, and blood biochemical parameters in small-sized meat ducks. A total of 500 healthy 21-day-old male ducks were housed in individual cages until slaughter at 63 d of age. The growth performance was determined for all the ducks. The carcass yield, meat quality, and blood biochemical parameters were determined for the selected 30 high-RFI (HRFI) and 30 low-RFI (LRFI) ducks. In terms of growth performance, the RFI, feed conversion ratio (FCR), and average daily feed intake (ADFI) were found to be significantly lower in the LRFI group (P < 0.01), whereas no differences were observed in the BW and body weight gain (P > 0.05). For slaughter performance, no differences were observed in the carcass traits between the LRFI and HRFI groups (P > 0.05). For meat quality, the shear force of breast muscle was significantly lower in the LRFI group (P < 0.05), while the other meat quality traits of breast and thigh muscles demonstrated no differences (P > 0.05). For blood biochemical parameters, the serum concentrations of triglycerides (TG) and glucose (GLU) were significantly lower in the LRFI group (P < 0.05), while the other parameters showed no differences (P > 0.05). The correlation analysis demonstrated a high positive correlation between RFI, FCR, and ADFI (P < 0.01). The RFI demonstrated a negative effect on the breast muscle and lean meat yields, but a positive effect on the shear force of breast muscle (P < 0.05). Further, the RFI demonstrated a positive effect on the TG and GLU levels (P < 0.05). These results indicate that the selection for low RFI could improve the FE of small-sized meat ducks without affecting the production performance. This study provides valuable insight into the biological processes underlying the variations in FE in small-sized meat ducks.

Two methodologies of the rendezvous procedure to establish ureteral continuity from a delayed ureteral leak following pelvic surgery

BACKGROUND

Ureteral trauma recognized in the operating theater is managed, for the most part, at the same surgical procedure oftentimes with urologic consultation. A delayed urine leak presents unique problems in that direct access to the site of the leak is not possible except by a reoperative procedure.

METHODS

In patients who develop delayed urine leakage following cancer surgery, the leakage may be controlled by the collaborative efforts of a urologist and interventional radiologist. Success depends on placement of a nephroureteral stent by the rendezvous procedure.

RESULTS

The sequence of procedures to reestablish ureteral continuity following a delayed leak are important in the successful placement of a nephroureteral stent. In the first methodology, through a percutaneous nephrostomy, a guidewire is placed in the ureter and down to the ureteral defect. The guidewire is then recovered and advanced into the bladder using a ureteroscope and grasping forceps. A nephroureteral stent is placed over the guidewire to bridge the gap and stent the ureteral defect. In the second methodology, the urologist passed a guidewire into the distal ureter, out of the ureteral defect, and into the free peritoneal space. Under fluoroscopic control, the wire loop must snare the ureteral guidewire and pull it out at the percutaneous nephrostomy. The nephroureteral stent is passed over the ureteral wire into the bladder.

CONCLUSIONS

Two different methodologies were described to complete the rendezvous procedure. It can be successful a large percentage of the time with a delayed ureteral leakage. Success requires a combined interventional radiology and urologic procedure.

Rare case of multifocal extradural and intramedullary neurosarcoidosis without pulmonary involvement: a case report and literature review

Introduction

Sarcoidosis is a multisystem disease characterized histologically by noncaseating granulomas. Localization of sarcoidosis to the CNS is termed neurosarcoidosis, a complex and rare neuroinflammatory form of sarcoidosis. When the spinal cord is involved, lesions are often intradural. Here, we present a rare case of progressive myelopathy secondary to multifocal spinal extradural neurosarcoidosis with spinal cord compression and without pulmonary involvement.

Case presentation

A 29-year-old African American female presented to the emergency department with numbness and paresthesia of 2-month duration in her left lower extremity and 2-week duration in her right lower extremity. The patient reported difficulty ambulating, paresthesia below the umbilicus, and back pain radiating to bilateral lower extremities. She endorsed 9-month history of cough, subjective fevers, night sweats, and unintentional 15 kg weight loss. Examination revealed 4/5 strength in the left lower extremity. MRI of the brain and spinal cord revealed enhancing extradural lesions, with spinal cord compression at T8 measuring 1.3 × 1.9 cm. Lumbar puncture demonstrated oligoclonal bands and increased CSF neutrophils, lymphocytes, monocytes, and protein. T8 laminectomy with resection of the epidural lesion was performed. Histology showed granulomas, consistent with neurosarcoidosis. At follow-up, repeat spinal MRI revealed disease progression with intramedullary involvement. Long-term immunosuppressive treatment was eventually initiated with satisfactory response.

Discussion

This is a rare case of myelopathy secondary to spinal extradural neurosarcoidosis. Spinal neurosarcoidosis is predominantly an intradural process. Our review of the literature identified only seven cases of extradural neurosarcoidosis presenting with compressive myelopathy. Additional insight into management and rehabilitation following pathological diagnosis is of clinical significance.

Bone and non-contractile soft tissue changes following open kinetic chain resistance training and testosterone treatment in spinal cord injury: an exploratory study

Twenty men with spinal cord injury (SCI) were randomized into two 16-week intervention groups receiving testosterone treatment (TT) or TT combined with resistance training (TT + RT). TT + RT appears to hold the potential to reverse or slow down bone loss following SCI if provided over a longer period.

INTRODUCTION

Persons with SCI experience bone loss below the level of injury. The combined effects of resistance training and TT on bone quality following SCI remain unknown.

METHODS

Men with SCI were randomized into 16-week treatments receiving TT or TT + RT. Magnetic resonance imaging (MRI) of the right lower extremity before participation and post-intervention was used to visualize the proximal, middle, and distal femoral shaft, the quadriceps tendon, and the intermuscular fascia of the quadriceps. For the TT + RT group, MRI microarchitecture techniques were utilized to elucidate trabecular changes around the knee. Individual mixed models were used to estimate effect sizes.

RESULTS

Twenty participants completed the pilot trial. A small effect for yellow marrow in the distal femur was indicated as increases following TT and decreases following TT + RT were observed. Another small effect was observed as the TT + RT group displayed greater increases in intermuscular fascia length than the TT arm. Distal femur trabecular changes for the TT + RT group were generally small in effect (decreased trabecular thickness variability, spacing, and spacing variability; increased network area). Medium effects were generally observed in the proximal tibia (increased plate width, trabecular thickness, and network area; decreased trabecular spacing and spacing variability).

CONCLUSIONS

This pilot suggests longer TT + RT interventions may be a viable rehabilitation technique to combat bone loss following SCI.

CLINICAL TRIAL REGISTRATION

Registered with clinicaltrials.gov : NCT01652040 (07/27/2012).

Inhibition of nucleophosmin 1 suppresses colorectal cancer tumor growth of patient -derived xenografts via activation of p53 and inhibition of AKT

The nucleophosmin 1 (NPM1) protein is frequently overexpressed in various cancers compared to normal tissues and represents a potential biomarker for maliganancy. However, its role in colorectal cancer (CRC) is still not fully understood. In this report, we show that NPM1 levels in CRC correlate with prognosis and sensitivity to chemotherapy. NPM1 expression was found to be significantly increased in CRC tumors (P < .001) and was associated with poor overall 5-year survival (P < .05). For individuals with Stage IV disease, this represented a reduction in survival by 11 months (P < .01; HR = 0.38, CI [0.21, 0.69]. In vitro, we show that NPM1 gene silencing enhanced the chemosensitivity of CRC cells and that pharmacological inhibition of NPM1 by NSC348884 triggered the onset of programmed cell death. Our immunofluorescence microscopy and immunoblot analyses also revealed that blocking NPM1 function sensitized CRC cells to chemotherapy-induced apoptosis through a mechanism that involves proteins in the AKT pathway. Consistent with the in vitro data, our patient-derived CRC xenograft model showed that inhibition of NPM1 suppressed tumor growth and attenuated AKT signaling in vivo. Moreover, LY294002, an inhibitor of the PI3K/AKT pathway, restored the chemosensitivity of CRC cells expressing high levels of NPM1. The findings that NPM1's expression in CRC tissue correlates with prognosis and supports anti-apoptotic activity mediated by AKT signaling, further our understanding of the role of NPM1 in CRC.

Survival and Operative Outcomes After Salvage Surgery for Recurrent or Persistent Anal Cancer

Anal squamous cell carcinoma (SCC) is a relatively rare cancer comprising less than 2.5% of all gastrointestinal malignancies. The standard treatment for anal SCC is primary chemoradiation therapy which can result in complete regression. After successful treatment, the 5-year survival is approximately 80%. However, up to 30% of patients experience recurrent persistent or recurrent disease. The role of surgery in the treatment of anal cancer, therefore, is limited to the management of recurrent or persistent disease with abdominoperineal resection and/or en bloc adjacent organ excision. Salvage surgery after irradiated anal cancer can be technically demanding in terms of acquisition of oncologically safe surgical margins and minimization of postoperative morbidity. In addition, 5-year survival outcomes after salvage resection have been reported to vary from 23% to 69%. Positive resection margins are generally regarded as the important risk factor associated with poor survival outcome. Perineal wound complications are the most common major postoperative morbidity. Because of the challenges of primary wound closure after salvage abdominoperineal resection, myocutaneous flap reconstruction has been performed to reduce the severity of perianal would complications. We, therefore, descriptively reviewed contemporary published evidence describing the treatment and outcomes after salvage surgery for persistent or recurrent anal SCC.

Evaluation of Prediction Accuracy for Volume of Distribution in Rat and Human Using In Vitro, In Vivo, PBPK and QSAR Methods

Volume of distribution at steady state (V_ss) is an important pharmacokinetic parameter of a drug candidate. In this study, V_ss prediction accuracy was evaluated by using: (1) seven methods for rat with 56 compounds, (2) four methods for human with 1276 compounds, and (3) four in vivo methods and three Kp (partition coefficient) scalar methods from scaling of three preclinical species with 125 compounds. The results showed that the global QSAR models outperformed the PBPK methods. Tissue fraction unbound (f_u,t) method with adipose and muscle also provided high V_ss prediction accuracy. Overall, the high performing methods for human V_ss prediction are the global QSAR models, Øie-Tozer and equivalency methods from scaling of preclinical species, as well as PBPK methods with Kp scalar from preclinical species. Certain input parameter ranges rendered PBPK models inaccurate due to mass balance issues. These were addressed using appropriate theoretical limit checks. Prediction accuracy of tissue Kp were also examined. The f_u,t method predicted Kp values more accurately than the PBPK methods for adipose, heart and muscle. All the methods overpredicted brain Kp and underpredicted liver Kp due to transporter effects. Successful V_ss prediction involves strategic integration of in silico, in vitro and in vivo approaches.

Experience With Cardiology-Oriented Outcomes in Critically Ill Patients With Coronavirus Disease 2019

OBJECTIVES

Coronavirus disease 2019 is associated with high mortality rates and multiple organ damage. There is increasing evidence that these patients are at risk for various cardiovascular insults; however, there are currently no guidelines for the diagnosis and management of such cardiovascular complications in patients with coronavirus disease 2019. We share data and recommendations from a multidisciplinary team to highlight our institution's clinical experiences and guidelines for managing cardiovascular complications of coronavirus disease 2019.

DESIGN SETTING AND PATIENTS

This was a retrospective cohort study of patients admitted to one of six ICUs dedicated to the care of patients with coronavirus disease 2019 located in three hospitals within one academic medical center in Atlanta, Georgia.

MEASUREMENTS/INTERVENTIONS

Chart review was conducted for sociodemographic, laboratory, and clinical data. Rates of specific cardiovascular complications were assessed, and data were analyzed using a chi-square or Wilcoxon rank-sum test for categorical and continuous variables. Additionally, certain cases are presented to demonstrate the sub committee's recommendations.

MAIN RESULTS

Two-hundred eighty-eight patients were admitted to the ICU with coronavirus disease 2019. Of these, 86 died (29.9%), 242 (84.03%) had troponin elevation, 70 (24.31%) had dysrhythmias, four (1.39%) had ST-elevation myocardial infarction, eight (2.78%) developed cor pulmonale, and 190 (65.97%) with shock. There was increased mortality risk in patients with greater degrees of troponin elevation (p < 0.001) and with the development of arrhythmias (p < 0.001), cor pulmonale (p < 0.001), and shock (p < 0.001).

CONCLUSIONS

While there are guidelines for the diagnosis and management of pulmonary complications of coronavirus disease 2019, there needs to be more information regarding the management of cardiovascular complications as well. These recommendations garnered from the coronavirus disease 2019 cardiology subcommittee from our institution will add to the existing knowledge of these potential cardiovascular insults as well as highlight suggestions for the diagnosis and management of the range of cardiovascular complications of coronavirus disease 2019. Additionally, with the spread of coronavirus disease 2019, our case-based recommendations provide a bedside resource for providers newly caring for patients with coronavirus disease 2019.

Rendezvous procedure to establish ureteral continuity from a delayed ureteral leak following pelvic surgery. A case report

BACKGROUND

Iatrogenic damage to the ureter as a result of an abdominal or pelvic surgical procedure is unusual. However, it does occur and the surgeon must be prepared to deal knowledgeably with the injury. Leaks that are recognized within the operating theater are managed, for the most part, at the same surgical procedure oftentimes with urologic consultation. A delayed leak presents unique problems in that direct access to the site of the leak is not possible except by a reoperative procedure. Delayed leaks present a clinical situation involving the urologist, interventional radiologist, as well as the surgeon.

METHODS

A patient who developed delayed urine leakage following a partial sacrectomy to remove recurrent mucinous appendiceal malignancy was studied. The leakage was controlled using a nephroureteral stent. Placement of the nephroureteral stent was made possible by the rendezvous procedure.

RESULTS

The sequence of procedures to reestablish ureteral continuity following a delayed leak are important in the successful placement of a nephroureteral stent. After establishing the site of the injury a percutaneous nephrostomy must be placed. Then, through the nephrostomy, a guidewire is placed in the ureter to be recovered and advanced into the bladder using a ureteroscope and grasping forceps. A nephroureteral stent is placed over the guidewire to bridge the gap and stent the ureteral defect.

CONCLUSIONS

The rendezvous procedure can be successful a large percentage of the time with a delayed ureteral leakage. Successful recovery of a guidewire in the ureter by ureteroscopy requires a combined interventional radiology and urologic procedure.

Abstract A47: Circulating tumor cell-defined minimal residual disease in locally advanced rectal cancer treated with multimodality therapy

Background: Current treatment for locally advanced rectal cancer (LARC) includes multimodality therapy in the neoadjuvant and adjuvant settings. Response to neoadjuvant therapy (NT) is prognostic of long-term outcomes. While long-course chemoradiation (CRT) had been the traditional NT regimen, novel regimens adding systemic therapy and/or eliminating radiation have been introduced. We examined if circulating tumor cells provide prognostic information independent of the specific treatment regimen utilized. Specifically, we aimed to define the significance of CTC-defined minimal residual disease (MRD) in LARC.

Methods: A prospective longitudinal protocol enrolled LARC patients (N=100; clinical stage II=4; stage III=96) undergoing NT. Peripheral blood was collected at baseline (t1, treatment-naive), after NT (t2, intraoperatively before tumor manipulation), after resection (t3, 2-8 weeks postoperatively), and after completion of adjuvant therapy (t4, 2-12 weeks after completion). CTC was enumerated by the CellSearch® platform within 72 hours of collection. Patients were followed for disease-free survival (DFS).

Results: At t1, CTCs were detected in 28/90 (31.1%) patients with available samples with a median CTC count of 1.5 [IQR: 1.0, 2.75]. NT consisted of long-course pelvic CRT (65%), extended NT with systemic chemotherapy and long- or short-course pelvic CRT (22%), and a radiation-sparing regimen with systemic chemotherapy only (13%). At t2, CTCs were detected in 34/75 (45.3%) patients with a median CTC count of 1 [IQR: 1, 1]. Type of NAT did not correlate with CTC positivity (p=0.637). Ten (9.4%) patients declined surgery, while cPR occurred in 12/93 (12.9%) surgical patients. Postoperatively (t3), CTC was detected in 12/47 (25.5%) patients, with a median count of 1.5 (IQR: 1.0-3.0). After completing adjuvant chemotherapy (t4), only 3/29 (10.3%) patients had detectable CTC. With a median follow-up of 47.50 months from diagnosis for the entire cohort, CTC positivity at t4 significantly stratified DFS (p=0.035).

Conclusions: One third of locally advanced RC patients harbored detectable CTCs at baseline. CTC detection after completion of curative-intent multimodality therapy (i.e., MRD) correlated with long-term DFS.

Citation Format: Lucas Lee, Carol Hall, Antony Lucci, Brian Bednarski, Miguel Rodriguez-Bigas, George Chang, Y. Nancy You. Circulating tumor cell-defined minimal residual disease in locally advanced rectal cancer treated with multimodality therapy [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A47.

Research Note: Effects of the rearing method and stocking density on carcass traits and proximate composition of meat in small-sized meat ducks

The present study was conducted to evaluate the effects of different rearing methods and stocking densities on carcass yield and proximate composition of meat in small-sized meat ducks. A total of 555 one-day-old birds were randomly allocated to six treatment groups (three replicates per treatment, sex ratio 1/1) with a 2 × 3 factorial arrangement of two rearing methods (reared in cage or net) and three stocking densities (5 [low], 7 [medium], or 9 [high] birds/m²) until day 70. Five male and five female birds from each replicate were randomly selected and processed to determine the carcass yield. Proximate composition was determined by proximate analysis using the breast and thigh muscles. There was no interaction effect between the rearing method and stocking density on carcass yield. The rearing method affected the thigh muscle rate, which was higher in the cage groups (P < 0.05). The final BW and abdominal fat rate decreased with increasing density (P < 0.05), whereas the thigh muscle rate increased (P < 0.05). There were significant interaction effects (P < 0.05) between the rearing method and stocking density on the content of protein, fat, and collagen. The content of fat and moisture was greater and lower, respectively, in the cage groups (P < 0.05). The content of moisture, fat, and collagen with a medium density was higher (P < 0.05). In addition, the content of protein and fat was lower in the ducks fed in nets at low and high densities (P < 0.05), respectively; the collagen content of breast and thigh muscle was lower in the ducks fed in cages and nets, respectively, at a low density (P < 0.05). Our findings provide valuable insights into the single and interactive effects of the rearing method and stocking density on duck slaughter performance and proximate composition of meat. The results indicate that a rearing system with a cage pattern and a medium density is better than other arrangements for small-sized meat ducks.

Tunable anomalous Hall conductivity through volume-wise magnetic competition in a topological kagome magnet

Magnetic topological phases of quantum matter are an emerging frontier in physics and material science. Along these lines, several kagome magnets have appeared as the most promising platforms. Here, we explore magnetic correlations in the kagome magnet Co3Sn2S2. Using muon spin-rotation, we present evidence for competing magnetic orders in the kagome lattice of this compound. Our results show that while the sample exhibits an out-of-plane ferromagnetic ground state, an in-plane antiferromagnetic state appears at temperatures above 90 K, eventually attaining a volume fraction of 80% around 170 K, before reaching a non-magnetic state. Strikingly, the reduction of the anomalous Hall conductivity (AHC) above 90 K linearly follows the disappearance of the volume fraction of the ferromagnetic state. We further show that the competition of these magnetic phases is tunable through applying either an external magnetic field or hydrostatic pressure. Our results taken together suggest the thermal and quantum tuning of Berry curvature induced AHC via external tuning of magnetic order.

Determining the Efficacy of Liquid Sporicides Against Spores of Bacillus subtilis on a Hard Nonporous Surface Using the Quantitative Three Step Method: Collaborative Study

A collaborative study was conducted to validate the quantitative Three Step Method (TSM), a method designed to measure the performance of liquid sporicides on a hard nonporous surface. Ten laboratories agreed to participate in the collaborative study; data from 8 of 10 participating laboratories were used in the final statistical analysis. The TSM uses 5 5 1 mm glass coupons (carriers) upon which spores have been inoculated and which are introduced into liquid sporicidal agent contained in a microcentrifuge tube. Following exposure to a test chemical and a neutralization agent, spores are removed from carriers in 3 fractions: passive removal (Fraction A), sonication (Fraction B), and gentle agitation (Fraction C). Liquid from each fraction is serially diluted and plated on a recovery medium for spore enumeration. Control counts are compared to the treated counts, and the level of efficacy is determined by calculating the log10 reduction (LR) of spores. The main statistical goals were to evaluate the repeatability and reproducibility of the LR values, to estimate the components of variance for LR, and to assess method responsiveness. AOAC Method 966.04Method II was used as a reference method. The scope of the validation was limited to testing liquid formulations against spores of Bacillus subtilis, a surrogate for virulent strains of B. anthracis, on a hard nonporous surface (glass). The test chemicals used in the study were sodium hypochlorite, a combination of peracetic acid and hydrogen peroxide, and glutaraldehyde. Each test chemical was evaluated at 3 levels of presumed efficacy: high, medium, and low. Three replications were required. The TSM was validated as it successfully met the statistical parameters for quantitative test methods. Satisfactory validation parameters, such as the repeatability standard deviation (Sr) and reproducibility standard deviation (SR), were obtained for control carrier counts and LR values. Both the TSM and the reference method were responsive to the efficacy levels of the test chemicals. For the 72 total TSM tests conducted, the mean ( standard error of the mean) log density of spores per control carrier was 6.86 ( 0.08); the Sr and SR were low at 0.15 and 0.27, respectively. Across the range of test chemicals, the Sr and SR estimates associated with LR were also acceptably low. The Sr rangedfrom 0.17 to 0.72 and the SR ranged from 0.34 to 1.43. Overall, the Sr and SR estimates associated with the efficacy data were within the ranges published for other quantitative methods and meet the performance characteristics necessary for validation.

Prediction of Fraction Unbound in Microsomal and Hepatocyte Incubations: A Comparison of Methods across Industry Datasets

The fraction unbound in the incubation, f_u,inc, is an important parameter to consider in the evaluation of intrinsic clearance measurements performed in vitro in hepatocytes or microsomes. Reliable estimates of f_u,inc based on a compound's structure have the potential to positively impact the screening timelines in drug discovery. Previous works suggested that f_u,inc is primarily driven by passive processes and can be described using physicochemical properties such as lipophilicity and the protonation state of the molecule. While models based on these principles proved predictive in relatively small datasets that included marketed drugs, their applicability domain has not been extensively explored. The work presented here from the in silico ADME discussion group (part of the International Consortium for Innovation through Quality in Pharmaceutical Development, the IQ consortium) describes the accuracy of these models in large proprietary datasets that include several thousand of compounds across chemical space. Overall, the models do well for compounds with low lipophilicity. In other words, the equations correctly predict that f_u,inc is, in general, above 0.5 for compounds with a calculated logP of less than 3. When applied to lipophilic compounds, the models failed to produce quantitatively accurate predictions of f_u,inc, with a high risk of underestimating binding properties. These models can, therefore, be used quantitatively for less lipophilic compounds. On the other hand, internal machine-learning models using a company's own proprietary dataset also predict compounds with higher lipophilicity reasonably well. Additionally, the data shown indicate that microsomal binding is, in general, a good proxy for hepatocyte binding.

Abstract P5-04-16: Total estrogenic activity during neoadjuvant therapy with letrozole and exemestane – An intra-patient cross-over comparison using the AroER tri-screen

Background. Aromatase inhibitors (AIs), letrozole (Femarâ / Femaraâ) and exemestane (Aromasinâ), are widely used anti-hormonal drugs for breast cancer. Both compounds strongly reduce circulating estradiol levels in postmenopausal women. In the setting of metastatic breast cancer, these drugs may be used after another, causing new responses in selected patients by switching to the alternative drug after progressing on the first choice. This well-known ”lack of cross resistance” has been recognized for some time and is documented by several clinical trials. However, the precise explanation for this clinical observation is still unknown. The availability of mechanistic information may lead to an improved strategy against hormone-sensitive breast cancer.

Patients and methods. NEO-LET-EXE was a neoadjuvant, randomized, open-label, intra-patient cross-over trial. Postmenopausal patients with estrogen receptor (ER) positive (&gt;50%), HER-2 negative, locally advanced breast cancer were enrolled. Sequential blood samples (obtained at baseline, after 2 months and 4 months of treatment) were available from 29 patients. All patients were randomized to sequential treatment starting with either letrozole (2.5 mg o.d.) or exemestane (25 mg o.d) for 2 months followed by another 2 months on the alternative compound. The total estrogenic activities in the collected blood samples were determined using AroER tri-screen assay developed by the Chen laboratory. The assay utilizes MCF-7aro ERE cells which contain both aromatase and ER. The samples were assayed in the presence as well as the absence of letrozole, to estimate relative contributions of estrogen and estrogen+androgen to the activities, respectively.

Results. Using the highly sensitive AroER tri-screen assay, estrogenic activity were detected at three time points in all blood samples. Importantly, a significantly higher total estrogenic activity was found during therapy with exemestane compared to letrozole in 23 out of 26 patients. Only in three patients, the activity was higher during therapy with letrozole compared to exemestane. When letrozole was included in the assay, the estrogenic activities in most samples collected during exemestane treatment were further reduced, suggesting that low levels of androgen were present in samples from exemestane treatment. Four samples collected after exemestane treatment and three after letrozole treatment had higher activities than baseline samples when assay was carried out with letrozole.

Discussion. Our results suggest the AroER tri-screen to be a very sensitive method to estimate the overall estrogen-mediated activity in human samples. Significant higher levels of estrogenic activity in human serum were observed during exemestane than those during letrozole treatment. Our observations, that additional letrozole could reduce further the estrogen activity in the exemestane-treated samples, demonstrate probably residual aromatase activity during therapy with exemestane alone.In addition to distinguish the effects of exemestane and letrozole, our results also demonstrate that the assay can also potentially detect the effects of estrogenic mimics.

Citation Format: Bahrami N, Chang G, Kanaya N, Sauer T, Gravdehaug B, Chen S, Geisler J. Total estrogenic activity during neoadjuvant therapy with letrozole and exemestane – An intra-patient cross-over comparison using the AroER tri-screen [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 P5-04-16.