Clinical Acceptability of Artificial Intelligence-Screened Interstitial Lung Disease (AI-ILD) in Lung Cancer Patients Treated with Radiotherapy

PURPOSE/OBJECTIVE(S)

Patients with interstitial lung disease (ILD) treated with thoracic radiotherapy (RT) are at greater risk of pulmonary toxicity. Automatic universal screening for ILD allows radiation oncologists (ROs) to risk stratify patients and implement necessary modifications to their respiratory monitoring or treatment. Automatic screening however may affect RO workload and so it is imperative to assess the clinical acceptability of this tool.

MATERIALS/METHODS

We have developed a machine learning algorithm to identify patients who are at high risk of having ILD based on RT planning computed tomography (CT) images. A quality improvement (QI) project was initiated to test feasibility and acceptability of the machine learning algorithm. If positive, the results of the machine learning algorithm were made available to ROs via structured electronic reporting. ROs were prompted to review the patient and consider expert radiologist consultation if thought appropriate. All electronic surveys and qualitative comments were summarized to describe clinical acceptability. Expert radiologist established gold standard ILD status of all patients on the study. A formal review of RO feedback was collected for all screen-positive, true-positive cases.

RESULTS

Two hundred forty cases were screened of which 45 were flagged as AI-ILD positive and the responsible RO notified. Of these 45 screen-positive cases, all continued on to RT except for 3 patients with tumor progression. From these 45, 24 surveys were completed, 21 had no prior suspicion of ILD. There were 7 true-positives, of which 1 had a survey response. Based on the survey responses, 88% of cases underwent review by the responsible RO. In 16 cases this automatic notification prompted case consultation with an expert radiologist. Expert review was performed from 10 minutes up to 53 hours after the email prompt to the radiologist, with median response time of 1.5 hours. In the 7 screen-positive, true-positive cases, only 2 were not previously known to the responsible RO. In the two cases where true-positive ILD status was previously unknown, one was a mild case of ILD and the other had previously received thoracic RT at this institution without ILD being identified, in both cases the ROs were grateful that this diagnosis was identified prior to treatment. RO confidence in the machine learning prediction was moderate due to the high proportion of false positives.

CONCLUSION

Based on available survey results, more than 75% of the screen-positive cases were reviewed by the responsible RO and two-thirds of these involved expert radiology input. RO feedback was generally positive and this tool was rated as a net benefit despite the high rate of false-positives and the need for clarification.

Association of Artificial Intelligence-Screened Interstitial Lung Disease with Radiation Pneumonitis and Mortality in Locally Advanced Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Radiation pneumonitis (RP) is a common and dose-limiting toxicity following radiotherapy for non-small cell lung cancer (NSCLC). Patients with interstitial lung disease (ILD) are believed to be at increased risk of developing complications including RP, ILD progression, or death. An automated method to identify patients prior to radiotherapy at high risk of developing toxicities or death may allow clinicians to mitigate risk through informed treatment planning and careful patient monitoring.

MATERIALS/METHODS

All locally advanced NSCLC patients treated with definitive radiation from 2006-2021 with a minimum 1 year of follow-up were assessed. RP and mortality data were prospectively collected and retrospectively reviewed. A convolutional neural network (CNN) was previously developed and validated to identify patients with radiographic ILD using planning computed tomography (CT) images, with an accuracy of 0.82. Planning CT scans for the retrospective cohort were used as input to the CNN, with artificial intelligence-screened ILD (AI-ILD) score as an output. AI-ILD scores above our established threshold were labeled as AI-ILD+. The association between AI-ILD score, AI-ILD+/-, mean lung dose (MLD), and the primary outcome of grade ≥2 (G2+) RP or mortality, as well as the secondary outcomes of G2+ RP and mortality were assessed using Wilcoxon rank sum test, univariate and multivariable logistic regression, and Kaplan-Meier survival analysis.

RESULTS

Of 799 patients reviewed, 745 eligible patients were included in the analysis; grade 0-5 RP was reported in 51.3%, 27.1%, 16.9%, 4.0%, 0.1%, and 0.5% of patients respectively. Overall, 22.9% of patients were AI-ILD+, and therefore at high risk (>20% chance) of having true ILD. On UVA, AI-ILD score, AI-ILD+ and MLD were significantly associated with the primary outcome of G2+ RP or mortality, as well as the secondary outcome of mortality. However, only MLD was significantly associated with the secondary outcome of G2+ RP. On MVA, both AI-ILD+ (OR 1.42, 95% CI 1.02-1.97, p = 0.04) and MLD (OR 1.13, 95% 1.05-1.21, p = 0.008) were significantly associated with G2+ RP or mortality. On Kaplan-Meier analysis, the median toxicity-free survival (TFS) time for AI-ILD+ and AI-ILD- patients were 1.7 and 3.4 years respectively, with a 2-year TFS of 48.3% vs. 59.3% (log-rank test: p = 0.02). There was no significant difference in rates of G2+ RP.

CONCLUSION

The AI-ILD algorithm can detect high risk patients with significantly decreased TFS following definitive treatment for NSCLC. AI-ILD classification was not associated with a significant difference in rates of RP when accounting for MLD. Future work will focus on improving the classification algorithm, expert radiologist validation of this dataset, and exploring reasons for the mortality difference in AI-ILD+ patients.

A Transcriptome-Based Precision Oncology Platform for Patient-Therapy Alignment in a Diverse Set of Treatment-Resistant Malignancies

Predicting in vivo response to antineoplastics remains an elusive challenge. We performed a first-of-kind evaluation of two transcriptome-based precision cancer medicine methodologies to predict tumor sensitivity to a comprehensive repertoire of clinically relevant oncology drugs, whose mechanism of action we experimentally assessed in cognate cell lines. We enrolled patients with histologically distinct, poor-prognosis malignancies who had progressed on multiple therapies, and developed low-passage, patient-derived xenograft models that were used to validate 35 patient-specific drug predictions. Both OncoTarget, which identifies high-affinity inhibitors of individual master regulator (MR) proteins, and OncoTreat, which identifies drugs that invert the transcriptional activity of hyperconnected MR modules, produced highly significant 30-day disease control rates (68% and 91%, respectively). Moreover, of 18 OncoTreat-predicted drugs, 15 induced the predicted MR-module activity inversion in vivo. Predicted drugs significantly outperformed antineoplastic drugs selected as unpredicted controls, suggesting these methods may substantively complement existing precision cancer medicine approaches, as also illustrated by a case study.

SIGNIFICANCE

Complementary precision cancer medicine paradigms are needed to broaden the clinical benefit realized through genetic profiling and immunotherapy. In this first-in-class application, we introduce two transcriptome-based tumor-agnostic systems biology tools to predict drug response in vivo. OncoTarget and OncoTreat are scalable for the design of basket and umbrella clinical trials. This article is highlighted in the In This Issue feature, p. 1275.

NCOG-24. TIME TO FIRST RECURRENCE AND SURVIVAL IN IDH-WILDTYPE GLIOBLASTOMA

INTRODUCTION

Time to recurrence is a source of considerable anxiety in glioblastoma. Assuming survival to a certain timepoint without tumor progression, how do odds/outcomes change relative to initial starting conditions? Is there a single timepoint with highest risk of tumor progression, after which "the longer you go, the longer you go"?

METHODS

Newly-diagnosed glioblastomas were retrospectively reviewed (n=209). Pre-2012 diagnoses (n=2) & IDH-mutants excluded (n=8). Median PFS/OS and remaining time to mPFS were calculated for sub-populations without disease progression (POD) at 0, 3, 6, 8, 12, and 24 months post-surgery.

RESULTS

199 IDH-wildtype glioblastomas identified -- 40% women, median age 63 years (range 26-91), 43% gross-total resection, 65% MGMT unmethylated, 65% upfront RT 60Gy (23% 40Gy) -- mPFS 8 months / mOS 19 months. Patients without POD within 3 months had mOS 20 months. Outcomes progressively improve at later timepoints-- mPFS 10/13/20/39 months and mOS 23/27/39/65 months, for patients without POD at 6/8/12/24 months post-surgery respectively. Patients without POD at 24 months comprised 10% of original cohort (n=20; 8 deaths). As a surrogate for risk of tumor progression, remaining time to mPFS was calculated (taken as difference between timepoint in question, and mPFS for the population of patients without POD up to that timepoint) and followed a J-shape curve -- 8 months (at 0 months post-surgery), 4 months (for patients without POD at 6 months post-surgery), 7-8 months (for patients without POD at 10-14 months post-surgery), to 13 and 15 months (for patients without POD at 18 and 24 months post-surgery, respectively).

DISCUSSION

Sub-populations without early progression appear to have improved survival relative to baseline, which has implications for clinical trials without internal controls. Nevertheless, highest risk for tumor progression seems to be at 6 months post-surgery, after which it appears "the longer you go, the longer you go."

CTNI-23. PRELIMINARY SAFETY AND PHARMACOKINETICS DATA FOR A PHASE 1B TRIAL OF TELAGLENASTAT IN COMBINATION WITH RADIATION THERAPY AND TEMOZOLOMIDE IN PATIENTS WITH IDH-MUTANT GRADE 2/3 ASTROCYTOMA (NCI-10218)

IDH mutant gliomas depend on glutaminase for glutamate/glutathione generation from glutamine because R-2-hydroxyglutarate inhibits branched chain amino acid transaminase mediated glutamate biosynthesis. Telaglenastat (CB-839 HCl) is a potent glutaminase-1 specific inhibitor which depletes tumor glutamate in orthotopic IDH mutant glioma PDX models and extends survival in these orthotopic models when added to radiation/temozolomide. NCI-10218 (NCT03528642) is a phase I clinical trial investigating the safety and tolerability of telaglenastat administered orally concurrently with standard doses of radiation (50.4 Gy, grade 2; 59.4 Gy, grade 3) and temozolomide (75 mg/m2 orally daily) in patients (age 16+) with previously untreated IDH mutant grade 2/3 astrocytoma. Telaglenastat dose was escalated in cohorts (400-800 mg twice daily) based on a standard 3 + 3 design to determine the recommended phase 2 dose (RP2D). Toxicities were graded per CTCAE v5.0. An expansion cohort additionally incorporated a seven-day run-in of telaglenastat monotherapy at RP2D prior to radiation to evaluate the pharmacodynamic impact of telaglenastat on plasma and tumor metabolites. 23 patients with IDH mutant astrocytoma (WHO grade 2, n = 5; WHO grade 3, n = 18) were accrued between December 2018 and January 2022 (Dose Escalation: 16; Dose Expansion: 7). Median age was 32 years (range 23-69 years). 61% were male and 70% were ECOG 0. No dose-limiting toxicities were observed. Grade 3/4 adverse events (independent of attribution) included: lymphopenia (3), neutropenia (2), leukocytosis (2), alanine transaminase elevation (2), thrombocytopenia (1), leukopenia (1), maculopapular rash (1), hyperglycemia (1), hyponatremia (1). The RP2D of concurrent telaglenastat was defined as 800 mg twice daily. Following peak absorption on Day 15 at RP2D, the mean (%CV) terminal elimination half-life in the plasma was 4.2 (53.5%) hours (range 2.1-7.1 hours). The Cmax, Tmax, oral clearance, and AUC were 1496 ng/mL, 4.0 hr, 93.6 L/hr/m2, and 7430 ng/mL*hr, respectively.

CTNI-50. A RANDOMIZED PHASE 2 TRIAL OF CEDIRANIB/OLAPARIB VERSUS BEVACIZUMAB IN PATIENTS WITH RECURRENT GLIOBLASTOMA: UPDATED RESULTS

PURPOSE

Hypoxia from inhibition of angiogenesis reduces DNA repair capacity. Targeting homologous recombination pathway also has anti-angiogenic effects. To examine the synergistic effects of disrupting DNA repair pathways and angiogenesis in glioblastoma, we combine cediranib (ced), a pan vascular endothelial growth factor (VEGF) receptor inhibitor with olaparib (ola), a poly-ADP ribose polymerase (PARP) inhibitor compared with bevacizumab (bev), a VEGF-A inhibitor alone. To identify potential biomarkers predicting response to treatments, we also perform whole exome sequencing on archival tissues.

METHODS

Bevacizumab-naïve adult patients with first or second recurrence of glioblastoma after radiation and temozolomide were randomly assigned to cediranib (30mg PO daily)/olaparib (200mg PO twice daily) or bevacizumab (10mg/kg IV every 2 weeks). The primary end point was progression-free survival (PFS) at 6 months. The secondary end points included safety and overall survival (OS). Whole exome sequencing of formalin-fixed paraffin embedded archival tissue from 23 patients was performed.

RESULTS

We are presenting the final data from this trial. Between December 2017 and November 2018, a total 70 adult patients with recurrent glioblastoma were randomly assigned to receive ced/ola (n = 35) or bev (n = 35). With a data cut off on 5/30/2022, median PFS was 118 days and 92 days in ced/ola and bev groups, respectively (hazard ratio, 1.099, 95% CI 0.6-2, p = 0.76). Median overall survival was 269.5 days and 192 days in ced/ola and bev groups, respectively (hazard ratio, 0.6892, 95% CI 0.39-1.2, p = 0.2). Whole exome sequencing was performed in total 23 patients (24 samples), 14 patients in the ced/ola group and 9 patients in the bev group.

CONCLUSION

No significant survival benefit was observed in patients with recurrent glioblastoma treated with ced/ola compared to patients treated with bev monotherapy. Potential biomarkers predicting response to treatment identified from the whole exome sequencing on archival tissues will be presented.

Thoracic low grade glial neoplasm with concurrent H3 K27M and PTPN11 mutations

We present the case of a 41-year-old man who developed worsening mid-thoracic back pain and imaging revealed a well-circumscribed intramedullary tumor in the thoracic spinal cord. Subtotal resection was performed, and histopathological analysis showed a cytologically bland, minimally proliferative glial neoplasm. Sequencing revealed H3 K27M and an activating PTPN11 mutation. Serial imaging revealed slow tumor regrowth over a three year period which prompted a second resection. The recurrent tumor displayed a similar low grade-appearing histology and harbored the same H3 K27M and PTPN11 mutations as the primary. While the prognostic importance of isolated H3 K27M in spinal gliomas is well-known, the combination of these two mutations in spinal low grade glioma has not been previously reported. Importantly, PTPN11 is a component of the MAPK signaling pathway. Thus, as building evidence shows that low grade-appearing gliomas harboring H3 K27M mutations along with BRAF or FGFR1 mutations have a relatively more favorable course compared to isolated H3 K27M-mutant midline gliomas, the present case provides new evidence for the prognostic importance of activating mutations in other components of the MAPK signaling pathway. This case further highlights the importance of clinico-radio-pathologic correlation when incorporating evolving genetic data into the integrated diagnosis of rare neuroepithelial tumors.

CTNI-40. EVALUATING FEASIBILITY AND EFFICIENCY OF PHASE II ADAPTIVE PLATFORM TRIAL DESIGNS BASED ON THE INDIVIDUALIZED SCREENING TRIAL OF INNOVATIVE GLIOBLASTOMA THERAPY (INSIGhT) EXPERIENCE

BACKGROUND

The Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) is a phase II platform trial with Bayesian adaptive randomization and deep genomic profiling to more efficiently test experimental agents in newly diagnosed glioblastoma and to prioritize therapies for late-stage testing.

METHODS

In the ongoing INSIGhT trial, patients with newly diagnosed MGMT-unmethylated glioblastoma are randomized to the control arm or one of three experimental therapy arms (CC-115, abemaciclib, and neratinib). The control arm therapy is radiotherapy with concomitant and adjuvant temozolomide, and primary endpoint is overall survival. Randomization has been adapted based on Bayesian estimation of biomarker-specific probability of treatment impact on progression-free survival (PFS). All tumors undergo detailed molecular sequencing, and this is facilitated with the companion ALLELE protocol. To evaluate feasibility of this approach, we assessed the status of this ongoing trial.

RESULTS

Since INSIGhT was activated 4.3 years ago, it has expanded to include 12 sites across the United States. A total of 247 patients have been enrolled. Randomization probabilities have been repeatedly adjusted over time based upon early PFS results to alter the randomization ratio from standard 1:1:1:1 randomization. All three arms have completed accrual and efficacy estimates are available based upon comparison to the common control arm in context of relevant biomarkers. There are 87 patients alive and in follow-up, and there are ongoing plans to add additional arms to evaluate further treatments in the future.

CONCLUSION

The INSIGhT trial demonstrates that a multi-center Bayesian adaptive platform trial is a feasible and effective approach to help prioritize therapies and biomarkers for newly diagnosed GBM. The trial has maintained robust accrual, and the simultaneous testing of multiple agents, sharing a common control arm and adaptive randomization serve as features to increase trial efficiency relative to traditional clinical trial designs.

NCOG-27. STATUS AS A CLINICAL TRIAL PARTICIPANT AND OUTCOME IN IDH-WILDTYPE GLIOBLASTOMA

INTRODUCTION

Standard of care for glioblastoma consists of surgery, followed by combined chemoradiation and adjuvant chemotherapy, as per the seminal EORTC study from 2005. Clinical trial patients, being a population selected for functional status, hepatic function, renal function, and lack of other malignancies, may have improved outcome over the general treated population.

METHOD

Single center retrospective analysis of status as a clinical trial patient in the upfront setting and other clinical factors/biomarkers, analyzed for correlation with outcomes (PFS/OS) in IDH-wildtype glioblastomas.

RESULTS

82 patients with IDH-wildtype glioblastoma were identified between 2014 and 2020, treated with standard of care or with an upfront clinical study (43% women; median age 66 years, range 35-91 years of age). 22 patients (27%) were treated with upfront clinical study. Status as a patient treated in an upfront clinical study did not correlate with outcome (hazard ratio HR PFS 0.99, CI 0.57-1.7, p=0.97; HR OS 1.09, CI 0.56-2.1, p=0.81). Frontal lobe was most frequently involved (n=36, 44%), followed by parietal lobe (n=33, 40%). Age was not a strong predictor of survival (R2 0.01). No statistically significant correlation was observed between outcome and laterality or location. MGMT promoter methylation was associated with improved PFS (HR 0.56, CI 0.33-0.94, p=0.03) and OS (HR 0.40, CI 0.19-0.85, p=0.02), with mPFS 6 months vs 9 months and mOS 16 months vs 20 months (unmethylated vs methylated respectively).

CONCLUSION

In this retrospective cohort of IDH-wildtype glioblastomas, age, tumor laterality, and tumor location were not significant predictors of outcome. MGMT promoter methylation predicted for superior PFS/OS. Patient selection for clinical studies are influenced by entry criteria, however at least in this retrospective review, status as a clinical study patient in the upfront setting did not correlate with outcome compared to patients treated with upfront standard of care.

CTNI-05. PRELIMINARY RESULTS OF THE NERATINIB ARM IN THE INDIVIDUALIZED SCREENING TRIAL OF INNOVATIVE GLIOBLASTOMA THERAPY (INSIGHT): A PHASE II PLATFORM TRIAL USING BAYESIAN ADAPTIVE RANDOMIZATION

BACKGROUND

EGFR is amplified in over 50% of glioblastoma and 20-30% have EGFRvIII mutations. Neratinib is a potent inhibitor of EGFR/HER2 approved for metastatic HER2+ breast cancer. To efficiently evaluate the potential impact of neratinib on overall survival (OS) in newly-diagnosed glioblastoma and to simultaneously develop information regarding potential genomic biomarker associations, neratinib was included as an arm on the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial. INSIGhT is a phase II platform trial using response adaptive randomization and deep genomic profiling to more efficiently test experimental agents in MGMT unmethylated glioblastoma and accelerate identification of novel therapies for phase III testing. Initial randomization was equal between neratinib, control, and two other experimental arms but subsequent randomization was adapted based on efficacy as determined by progression-free survival (PFS). We report preliminary results for the neratinib arm.

METHODS

Patients with newly diagnosed MGMT-unmethylated glioblastoma were randomized to receive either radiotherapy with concomitant and adjuvant temozolomide or standard radiochemotherapy followed by adjuvant neratinib (240 mg daily). Treatment continued until progression or development of unacceptable toxicities. The primary endpoint was OS. Association between neratinib efficacy and EGFR amplification was also investigated.

RESULTS

There were 144 patients (70 control; 74 neratinib). Neratinib was reasonably well-tolerated with no new toxicity signals identified. PFS was compared (HR 0.84; p=0.38, logrank test – not significant) between the neratinib (median 6.05 months) and control (median 5.82 months) arms. For patients EGFR pathway activation the PFS HR was 0.53 (p-value=0.03 – significant, median PFS: neratinib, 6.21 months, control, 5.26 months). However, there was no significant improvement in OS in EGFR amplified/mutated patients (HR 1.05; p-value 0.87) between neratinib (median 14.2) compared to the control arm (median 14.6).

CONCLUSION

Neratinib prolonged PFS in the EGFR positive subpopulation but there was no overall PFS benefit, or any OS improvement.

Report of National Brain Tumor Society roundtable workshop on innovating brain tumor clinical trials: building on lessons learned from COVID-19 experience

On July 24, 2020, a workshop sponsored by the National Brain Tumor Society was held on innovating brain tumor clinical trials based on lessons learned from the COVID-19 experience. Various stakeholders from the brain tumor community participated including the US Food and Drug Administration (FDA), academic and community clinicians, researchers, industry, clinical research organizations, patients and patient advocates, and representatives from the Society for Neuro-Oncology and the National Cancer Institute. This report summarizes the workshop and proposes ways to incorporate lessons learned from COVID-19 to brain tumor clinical trials including the increased use of telemedicine and decentralized trial models as opportunities for practical innovation with potential long-term impact on clinical trial design and implementation.

Sex-dependent effects of social status on the regulation of arginine-vasopressin (AVP) V1a, oxytocin (OT), and serotonin (5-HT) 1A receptor binding and aggression in Syrian hamsters (Mesocricetus auratus)

Dominance status in hamsters is driven by interactions between arginine-vasopressin V1a, oxytocin (OT), and serotonin 1A (5-HT1A) receptors. Activation of V1a and OT receptors in the anterior hypothalamus (AH) increases aggression in males, while decreasing aggression in females. In contrast, activation of 5-HT1A receptors in the AH decreases aggression in males and increases aggression in females. The mechanism underlying these differences is not known. The purpose of this study was to determine if dominance status and sex interact to regulate V1a, OT, and 5-HT1A receptor binding. Same-sex hamsters (N = 47) were paired 12 times across six days in five min sessions. Brains from paired and unpaired (non-social control) hamsters were collected immediately after the last interaction and processed for receptor binding using autoradiography. Differences in V1a, OT, and 5-HT1A receptor binding densities were observed in several brain regions as a function of social status and sex. For example, in the AH, there was an interaction between sex and social status, such that V1a binding in subordinate males was lower than in subordinate females and V1a receptor density in dominant males was higher than in dominant females. There was also an interaction in 5-HT1A receptor binding, such that social pairing increased 5-HT1A binding in the AH of males but decreased 5-HT1A binding in females compared with unpaired controls. These results indicate that dominance status and sex play important roles in shaping the binding profiles of key receptor subtypes across the neural circuitry that regulates social behavior.

NIMG-67. DISAPPEARING DOTS – TRANSIENT LATE ENHANCING LESIONS YEARS AFTER BRAIN RADIOTHERAPY

BACKGROUND

Late-delayed radiation effects appear 6 months to years following radiotherapy. We characterize a species of small enhancing lesions in the late-delayed phase of post-radiotherapy that are distinct from the classic descriptions of radiation necrosis or pseudoprogression associated with mass effect and edema. These “disappearing dots” are small, do not exert mass effect nor edema, and spontaneously resolve.

METHOD

We retrospectively describe a series of cases with “disappearing dots” following brain radiotherapy.

RESULTS

There were 10 cases (4 men), median age 42 years (range 29-63). Diagnoses were glioblastoma (3); low grade astrocytoma, anaplastic astrocytoma, and anaplastic oligodendroglioma (2 each); and solitary fibrous tumor (1). All patients received 54-60 Gy (Gray) of external beam radiotherapy, except one (proton beam therapy to 60 cobalt Gray equivalent). Disappearing dots appeared at a median of 27 months (range 5-197) post-radiotherapy. Lesions were relatively small (~< 1 cm3), peri-ventricular, and within the radiotherapy field. Most enlarged before resolving. Advanced MR imaging and fluorodeoxyglucose (FGD)-PET results were inconsistent. Lesions persisted a median of 8.5 months (range 1-49) before spontaneous resolution. All were asymptomatic. Biopsy in one case revealed treatment effects rather than recurrent tumor.

CONCLUSIONS

Asymptomatic small periventricular enhancing lesions can develop and remit spontaneously, years following brain radiotherapy. Such disappearing dots should be part of the differential diagnosis along with tumor recurrence. of new enhancing lesions in the late-delayed phase post-radiotherapy.

CTNI-25. PHASE IB CLINICAL TRIAL OF CHRONIC CONVECTION-ENHANCED DELIVERY OF TOPOTECAN FOR RECURRENT GLIOBLASTOMA

OBJECTIVES

Convection-enhanced delivery (CED) provides pharmacokinetic advantages over systemic delivery for achieving cytotoxic drug levels into targeted regions of the brain. A major shortcoming of CED has been the need to limit treatment duration because of infection risks associated with external pumps. We engineered a subcutaneously implanted catheter-pump construct for prolonged CED which was successfully tested in a large animal model and then approved by the FDA for a Phase Ib clinical trial with topotecan in patients with refractory glioblastoma (IND 131889).

METHODS

Five patients with recurrent glioblastoma underwent surgical implantation of a subcutaneous pump and catheter that infused intracerebral topotecan over 30 days. Gadolinium was co-infused as a surrogate tracer and advanced non-invasive radiographic imaging was used to monitor drug distribution and pharmacological effects. Tissue from multiple radiographically-localized regions of each tumor and surrounding brain was procured pre-treatment at the time of catheter implantation and then post-treatment when tumors were surgically resected. Tissue was used for drug level measurements and advanced molecular, genomic and cellular analysis of treatment effects.

RESULTS

Treatments were successfully completed in all five patients without significant complications. The safety and tolerability of treatment was validated by quality-of-life measures and neurological assessments. Noninvasive imaging demonstrated large and stable drug distribution volumes. Comprehensive tissue analysis demonstrated effective targeting of mitotically active tumor cells while sparing neurons.

CONCLUSIONS

We engineered a subcutaneously implanted catheter-pump construct for chronic CED that was successfully tested in a Phase Ib clinical trial with topotecan in recurrent glioblastoma patients. Analysis of pre- and post-treatment tissue showed significant anti-tumor activity from topotecan that was not harmful to normal brain. Chronic CED combined with non-invasive real time drug distribution monitoring provides a safe and effective glioma strategy suitable for clinical use.

NCOG-58. IMPACT OF TIME FROM PRESENTATION TO TREATMENT INITIATION ON CLINICAL OUTCOMES IN CENTRAL NERVOUS SYSTEM LYMPHOMA

OBJECTIVE

To examine impact of time from presentation to treatment initiation (TPT) on clinical outcomes in a cohort of patients with central nervous system lymphoma (CNSL).

INTRODUCTION

Earlier work in our population found that multifocal disease, cerebrospinal fluid (CSF) sampling, and use of immunomodulatory therapies were associated with longer TPT in CNSL, but impact on clinical outcomes was not assessed.

METHODS

We retrospectively reviewed records of patients who were diagnosed with CNSL from 2010-2018 and treated at Columbia University Irving Medical Center (CUIMC). Regression models were applied to examine the impact of age, gender, response to methotrexate (MTX), use of radiation, and TPT >/= 30 days on survival 1 year from diagnosis (one-year survival), overall survival (OS), and functional independence (FI, defined as Karnofsky Performance Status (KPS) > 70).

RESULTS

There were sixty-nine patients (51% men; median age at diagnosis 70 years, range 21-90). Median TPT was 24 days (range 7-372). TPT was < 30 days in 59 (85%) and >/= 30 days in 10 (15%). One-year survival was 77%, and FI rate was 78%. Negative prognostic factors for OS were age > 65 years (HR 5.34, CI 1.20-24.30, p=0.03) and absence of complete response to MTX (HR 2.40, CI 0.87-6.69, p=0.09). Only complete response to MTX predicted both FI (OR 4.71, CI 1.17-19.02, p=0.03) and one-year survival (OR 6.77, CI 1.98-23.13, p=0.002). Notably, OS was numerically improved among patients with TPT >/= 30 days vs. < 30 days (HR 0.31, p=0.27), though this did not meet statistical significance.

CONCLUSIONS

Longer TPT has been associated with worse outcomes in systemic lymphoma, but such a correlation has not always been observed in brain cancers such as glioblastoma. We found no negative impact of longer TPT on survival or FI.

CTNI-11. CC-115 IN NEWLY DIAGNOSED MGMT UNMETHYLATED GLIOBLASTOMA IN THE INDIVIDUALIZED SCREENING TRIAL OF INNOVATIVE GLIOBLASTOMA THERAPY (INSIGHT): A PHASE II RANDOMIZED BAYESIAN ADAPTIVE PLATFORM TRIAL

BACKGROUND

CC-115 is an oral, CNS-penetrant, selective inhibitor of mammalian target of rapamycin kinase (mTOR) and deoxyribonucleic acid-dependent protein kinase (DNA-PK). Both targets are important in glioblastoma; PI3K/Akt/mTOR signaling is hyperactive in most glioblastomas, and DNA-PK is integral to repair of radiotherapy-mediated DNA damage. To investigate CC-115 in newly diagnosed glioblastoma and explore potential genomic biomarker associations, CC-115 was evaluated in the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial, an adaptive platform trial designed to efficiently test experimental agents.

METHODS

Adults with newly diagnosed MGMT-unmethylated glioblastoma, with genomic data available, are eligible for this ongoing trial. Patients are adaptively randomized to one of several experimental arms or the control arm: standard radiotherapy with concurrent and adjuvant temozolomide. The primary endpoint is overall survival (OS). Patients randomized to CC-115 (10mg po BID) received it concurrently with radiotherapy and as adjuvant monotherapy. As the first in-human use of CC-115 with radiation, a safety lead-in 3 + 3 design was used.

RESULTS

Twelve patients were randomized to CC-115; seven patients had possible treatment-related CTCAE grade > 3 toxicity, including four pre-specified dose-limiting toxicities: liver function abnormality (n=1), hyperlipidemia (n=1), lipase elevation (n=1) and cerebral edema (n=1). There was no significant difference in progression-free survival (PFS, median 4.2 months [CC-115] vs. 5.2 months, p=0.9) or OS (median 10.1 months [CC-115] vs. 14.5 months, p=0.9) compared to the 50 patients randomized to the control arm. Based on early PFS results, randomization probability to CC-115 decreased from 25% to < 10% at time of the trial arm closure.

CONCLUSION

Concurrent and adjuvant CC-115 was associated with toxicity and failed to improve PFS or OS. The INSIGhT trial design allowed for more efficient testing of CC-115, decreasing patients and resources allocated to a therapy that was discontinued due to concerns about toxicity and unfavorable risk-to-benefit ratio.

CTNI-12. PRELIMINARY RESULTS OF THE ABEMACICLIB ARM IN THE INDIVIDUALIZED SCREENING TRIAL OF INNOVATIVE GLIOBLASTOMA THERAPY (INSIGHT): A PHASE II PLATFORM TRIAL USING BAYESIAN ADAPTIVE RANDOMIZATION

BACKGROUND

The cyclin D-CDK4/6-Rb pathway is activated in most glioblastomas. Abemaciclib is a potent CDK4/6 inhibitor with good brain penetration approved for ER/PR/HER2- breast cancer. In order to efficiently evaluate the potential impact of abemaciclib on overall survival (OS) in newly diagnosed glioblastoma and to simultaneously develop information regarding potential genomic biomarker associations, abemaciclib was included as an arm on the Individualized Screening Trial of Innovative Glioblastoma Therapy (INSIGhT) trial. INSIGhT is a phase II platform trial using response adaptive randomization and deep genomic profiling to more efficiently test experimental agents in MGMT unmethylated glioblastoma and potentially accelerate identification of novel therapies for phase III testing. Initial randomization was equal between abemaciclib, control, and two other experimental arms but subsequent randomization was adapted based on efficacy as determined by progression-free survival (PFS). Ineffective arms were discontinued and new arms added by protocol amendment. We report preliminary results for the abemaciclib arm which has completed accrual.

METHODS

Patients with newly diagnosed MGMT-unmethylated glioblastoma were randomized to receive either radiotherapy with concomitant and adjuvant temozolomide at standard doses or standard radiochemotherapy followed by adjuvant abemaciclib (150–200 mg orally BID) without temozolomide. Treatment continued until progression or development of unacceptable toxicities. The primary endpoint was OS. Association between abemaciclib efficacy and cyclin D-CDK4/6-Rb pathway genomic alterations was also investigated.

RESULTS

There were 123 patients (50 control; 73 treated with abemaciclib). Abemaciclib was generally well-tolerated with no new toxicity signals identified. PFS was significantly longer (p=0.03, logrank test) with abemaciclib (median 6.31 months 95% CI [5.29, 8.18]) compared to the control arm (5.16 months 95% CI [4.37, 6.28]). 28/50 control and 36/73 abemaciclib patients remain alive.

CONCLUSION

Preliminary analysis suggests that abemaciclib increases PFS compared to control. Updated toxicity, PFS and survival data and potential genomic biomarker associations will be presented.

Recurrent massive pulmonary emboli in a critically ill patient with COVID-19

We report the haematological management of a critically ill patient with coronavirus disease 2019 (COVID-19), with recurrent massive pulmonary emboli. A previous healthy 56-year-old man presented to the emergency department with severe hypoxaemic respiratory failure due to suspected COVID-19. He required invasive mechanical ventilation and transfer to the intensive care unit for increasing ventilatory requirements and cardiovascular instability. A computed tomography (CT) pulmonary angiogram demonstrated large bilateral pulmonary emboli with right heart strain, for which he received intravenous systemic thrombolysis followed by therapeutic weight-adjusted anticoagulation with low molecular weight heparin (dalteparin). Two weeks later, following an acute respiratory deterioration, a repeat CT pulmonary angiogram demonstrated a new saddle embolus with right heart strain requiring another regime of intravenous systemic thrombolysis. This occurred despite anti-Xa-guided therapeutic anticoagulation. The dose of therapeutic dalteparin was increased incrementally to an eventual dose of 12,500 units twice daily. A low threshold for radiological imaging should be considered in all COVID-19 patients with acute cardiorespiratory deterioration. Multidisciplinary team discussions highlighted aspects of balancing the risks of bleeding from anticoagulation vs. risk of death from pulmonary embolism. This report highlights the need for further research into the underlying mechanisms and optimal management of thrombotic complications in COVID-19.

The association between range usage and tibial quality in commercial free-range laying hens

1. Bone tissue adapts continuously to metabolic calcium demands, as well as to external forces due to physical weight loading subject to hen movement. Limited calcium metabolism and, subsequently, its availability from the medullary bone, is a major factor contributing to reduced eggshell quality in hens in the late laying period (>60 weeks of age). 2. Increasing physical activity and biomechanical loading during hen rearing has been demonstrated to increase skeletal strength, enhancing bone mass as well as endocortical and periosteal bone metabolism. Presently, the consequences of range use during lay on bone quality characteristics in laying hens remain unknown. 3.The aims of this study were to characterise tibiotarsal bone indices and evaluate the impact of range access during lay on tibia bone quality in commercial free-range laying hens. 4. This exploratory study described and analysed the volumetric measurements, morphological mechanical and trabeculae indices of the tibiotarsal bone of 48 Lohmann Brown laying hens at 74 weeks of age. All bone parameters were obtained using micro-computed tomography and correlated with individual hen range use. 5. Range usage throughout lay was not associated with tibial trabecular architecture (bone volume and fraction, trabecular thickness, trabecular connectivity density and structural model index), or any other morphological characteristics (breaking strength, diaphyseal diameter, bone weight and bone mineral density) of the tibia (P > 0.05) when hens were 74 weeks of age. 6. The results demonstrated a large variation in individual bone characteristics and suggested that range usage was not associated with bone quality in commercial free-range laying hens used in this study. In conclusion, the bone health of free-range commercial laying hens may be positively impacted by other features, such as hen genetics, feed, the quality of pullet rearing, perch availability or other shed equipment, and the benefits of these variables exceed the benefit of range use.

Flock use of the range is associated with the use of different components of a multi-tier aviary system in commercial free-range laying hens

1. The objective of this study was to investigate the association of using a multi-tier aviary system and access to range on flock uniformity in free-range laying hens, and to determine whether the extent of range use or flock uniformity can be predicted from the use of different levels of the aviary system.2. A total of 13,716 Lohmann Brown hens from five commercial free-range flocks housed in identical houses on the same farm were individually weighed at 16 weeks of age and allocated to five replicate areas within each house. Hen movement in the multi-tier aviary system and on the range was individually monitored using radio frequency identification (RFID). All hens had access to the range from 18 to 22 weeks of age and were exposed to the same management conditions.3. Whilst only one flock significantly changed its flock uniformity with time, they differed from each other in uniformity and body weight (P = 0.001).4. Hens spent most of their available time on the lower aviary tier (7.29 ± 0.029 h/hen/day) and on the upper aviary tier (4.29 ± 0.024 h/hen/day) while the least amount of time was spent on the range and in the nest boxes (0.93 ± 0.005 h/hen/day and 1.48 ± 0.007 h, respectively, P = 0.001).5. Range use was negatively correlated (r = -0.30) to the time spent on the upper aviary tier and positively correlated (r = 0.46) to the time spent on the lower aviary tier (P = 0.001). Bivariate analysis revealed that range and upper aviary resp. lower aviary tier usage had a significant curvilinear association.6. In conclusion, the study showed that range use was associated to the time hens spent on the different tiers of the aviary system. Flock uniformity varied between flocks but was not associated with either range and aviary system usage.

HOUT-26. FACTORS ASSOCIATED WITH TREATMENT DELAY IN CENTRAL NERVOUS SYSTEM LYMPHOMA

OBJECTIVE

To identify clinico-radiographic characteristics associated with delayed treatment initiation in central nervous system lymphoma (CNSL).

INTRODUCTION

Clinical and radiographic characteristics of CNSL are often varied with a broad differential diagnosis, potentially leading to delays in diagnosis and treatment.

METHODS

A single-center retrospective review of clinico-radiographic data was performed at Columbia University Irving Medical Center in patients with pathologically confirmed CNSL diagnosed from 1/2010–12/2018. Descriptive statistics and univariate logistic regression were used to identify variables associated with delayed treatment. Using visual binning, delayed treatment time was designated as >33 days from first presentation to medical attention to first chemotherapy for CNSL. Variables of interest included demographic data, presenting symptomatology, radiographic characteristics, location of initial presentation, and diagnostic and therapeutic interventions performed before biopsy.

RESULTS

Seventy patients (36 men (51%); median age at diagnosis 70 years, IQR 14.75 years; median time from first presentation to treatment 21 days, IQR 41.25 days) were included. Presentation with cognitive deficits suggested a strong, but not statistically significant, association with delayed treatment (OR=1.93, p=0.20), whereas presentation with focal neurologic deficits suggested protection against delayed treatment (OR=0.25, p=0.05). Initial presentation to a hospital suggested a strong, but not statistically significant, trend against delayed treatment (OR=0.41, p=0.08). Multifocal disease on neuroimaging (OR=7.18, p=0.001), pre-biopsy cerebrospinal fluid (CSF) sampling (OR=5.18, p=0.002), and pre-biopsy immunomodulatory treatment (including high-dose intravenous corticosteroids) for suspected neuroinflammatory disease (OR=6.33, p=0.03) had statistically significant associations with delayed treatment. Antimicrobial treatment before biopsy for suspected CNS infection suggested a trend toward delayed treatment, but the association was not statistically significant (OR=5.1, p=0.06).

CONCLUSIONS

Multifocal disease and pre-biopsy CSF sampling and immunomodulatory therapy were associated with delayed treatment initiation for CNSL in our single-center cohort. Recognizing factors associated with delayed treatment may allow physicians to circumvent these factors and permit more rapid diagnosis through tissue sampling.

QOLP-32. PATTERNS OF CARE AT END OF LIFE IN PATIENTS WITH GLIOMA

OBJECTIVE

To understand patterns of care at end of life in glioma patients.

BACKGROUND

Patients with gliomas often inquire about end-of-life issues. Understanding common clinical outcomes of tumor progression and end-of-life circumstances may reduce anxiety among patients and caregivers and inform care planning.

METHODS

Following IRB approval, we retrospectively analyzed circumstances surrounding death among patients with intracranial gliomas at Columbia University Irving Medical Center from 1/2014-2/2019, including immediate cause and location of death and implementation of palliative measures. Information unavailable from the medical record was supplemented by caregivers.

RESULTS

Data were available for 152 patients (95 men, 57 women; median age at death 61.5 years). Failure to thrive with transition to supportive care (n=117, 77%) was the most common immediate cause of death. Others included infection (19, 13%; with pulmonary (12, 8%), urinary tract (5, 3%), CNS (4, 3%), and GI (2, 1%) sources); seizures (8, 5%); intracerebral hemorrhage (5, 3%); cerebral edema (4, 3%); pulmonary embolism (4, 3%); autonomic failure (2, 1%); hemorrhagic shock (2, 1%); respiratory failure of unknown cause (2, 1%); pulmonary edema (1, 1%); and cardiac arrhythmia (1, 1%). Ten patients had multiple causes of death. Seventy-three patients (48%) died at home with hospice. Other locations were inpatient hospice (40, 26%); acute care hospital (34, 22%) including 27 (18%) with and 7 (5%) without comfort measures; skilled nursing facility (4, 3%) including 3 (2%) with and 1 (1%) without comfort measures; or religious facility (1, 1%) with comfort measures. Acute cardiac and/or pulmonary resuscitation was performed in 20 patients (13%); 8 (5%) died with no comfort measures.

CONCLUSIONS

Failure to thrive with transition to supportive care was the most common (77%) immediate cause of death followed by infection (13%). Hospice and/or palliative measures were implemented in 95% of patients, though resuscitative efforts were performed in 13%.

ACTR-61. A RANDOMIZED PHASE 2 TRIAL OF CEDIRANIB IN COMBINATION WITH OLAPARIB VERSUS BEVACIZUMAB IN PATIENTS WITH RECURRENT GLIOBLASTOMA

BACKGROUND

Like most proliferating tumors, GBM relies heavily on accurate DNA repair for maintenance of genome stability. Dysfunction in repair of both single and double strand DNA breaks by PARP inhibition and impairment of homologous recombination, respectively, would be synthetically lethal. In this study we combined the PARP inhibitor olaparib with cediranib, a pan VEGF receptor inhibitor. Cediranib may mediate disruption in the homologous recombination pathway through its antiangiogenic properties.

METHODS

Through the Experimental Therapeutics Clinical Trials Network, we performed an open-label randomized phase II study of bevacizumab (BEV)- naive adult patients with first or second recurrence of glioblastoma after radiation and temozolomide. Patients were randomized 1:1 to receive either olaparib 200 mg by mouth twice daily with cediranib 30 mg by mouth daily or BEV 10 mg/kg IV every 2 weeks. The primary endpoint was progression-free survival at 6 months (PFS6). Secondary endpoints included safety and overall survival. Exploratory objectives included blood, tissue and imaging-based biomarkers of response to treatment.

RESULTS

Seventy patients were enrolled. Median age was 60.5 years (range: 19–79), 39% females, median KPS was 90 (range: 60–100). Baseline characteristics were well balanced. With a data cut-off of 5/2/2019, PFS6 was 14% [95% CI 4–30%] in the cediranib/olaparib arm vs 30.9% [95% CI 12.7–51.2%] in the BEV arm. Median OS was 247 days in the cediranib/olaparib arm vs 201 days in the BEV arm, HR 0.816, 95% CI (0.431, 1.546). Related grade 3, 4 or 5 toxicity was experienced in 29% vs 12% of patients for the cediranib/olaparib vs BEV arm.

CONCLUSION

Treatment with cediranib/olaparib failed to increase PFS and OS in patients with recurrent GBM. Blood, tissue and imaging correlates will be presented to help understand why this treatment combination was unsuccessful.

NIMG-62. ATYPICAL IMAGING CHARACTERISTICS OF PRIMARY CNS LYMPHOMA AT INITIAL PRESENTATION LEADS TO FREQUENT MISDIAGNOSIS AND DELAYS IN DIAGNOSIS

BACKGROUND

Primary CNS lymphoma (PCNSL) has protean appearances on magnetic resonance imaging (MRI) that may lead to delays in diagnosis.

METHODS

We retrospectively reviewed histologically-confirmed PCNSL at Columbia University Irving Medical Center (CUIMC, 2010–2019), and characterize imaging features on pre-treatment MRI scans.

RESULTS

64 patients were analyzed. 61 of 64 (95%) presented with enhancement. 35 of 64 (55%) were multiply enhancing, and 26 of 64 (41%) were singly enhancing (of which 2 were dural-based). 3 of 64 (5%) were non-enhancing. 42 of 59 (71%) had diffusion restriction. 36 of 49 (73%) lacked susceptibility. 40 of 64 (63%) were periventricular. 28 of 64 (43%) had callosal involvement. In 14 of 54 (26%), lymphoma was either not included in the differential or specifically noted less likely in radiographic report – this radiographically misdiagnosed group was significantly more likely to be either non-enhancing or non-periventricular (p=0.026). Furthermore, radiographic misdiagnosis was associated with an increased risk of a more than 14-day delay from the initial MRI to the initial invasive study, either lumbar puncture or brain biopsy (p=0.04). Presentation with a single enhancing lesion, on the other hand, was associated with significantly faster time to diagnosis – median 4.6 days (IQR 3) vs 21.6 days (IQR 4.5) from initial MRI (p=0.04).

CONCLUSION

In PCNSL, imaging characteristics influence outcomes. While a classic single enhancing lesion is associated with rapid diagnosis, non-enhancing and non-periventricular disease are the most likely to be misdiagnosed and require a heightened index of suspicion to avoid delays to diagnosis.

Free-range laying hens: using technology to show the dynamics and impact of hen movement

Free-range laying hens are provided with the opportunity to access various structural areas, including open floor space, feed areas, water lines, next boxes, perches, aviary tiers, winter gardens and ranges. Different individual location preferences can lead to the development of hen subpopulations that are characterised by various health, welfare and performance parameters. Understanding the complexity of hen movement and hen interactions within their environment provides an opportunity to limit the disadvantages that are associated with housing in loose husbandry systems and aids in decision-making. Monitoring hen movement using modern technologies such as radio-frequency identification (RFID), optical flow patterns, image analysis and three-dimensional (3D) cameras allows the accumulation of big data for data mining, clustering and machine learning. Integrating individual-based management systems into modern flock management will not only help improve the care of under-performing hens, but also ensure that elite hens are able to use their full genetic potential, allowing an ethical, sustainable and welfare friendly egg production. This review highlights the dynamics and impact of hen movement in free-range systems, reviews existing knowledge relevant for feeding hens in non-cage systems, and outlines recent technological advances and strategies to improve the management of free-range laying hens.

4 Use of topical haemostatic dressings in an extended field care model of external haemorrhage

Introduction

The use of Celox gauze has been established in military practice as an adjunct in the treatment of external haemorrhage. The future character of conflict means that casualties may take longer to reach definitive care. The aim of this study was to test whether Celox Rapid, a topical haemostatic dressing, would maintain haemostasis during extended use in a junctional haemorrhage model.

Methods

An anaesthetised swine underwent simultaneous bilateral femoral arteriotomies; after 30 s of free bleeding Celox Rapid gauze was applied to the wound and pressure was maintained for 1 min. Following inspection for re-bleeding the Celox gauze was covered with standard field dressings and checked for re-bleeding every hour until the 6 hours had elapsed or the animal deceased.

Results

There was no evidence of re-bleeding at any point up to and including 6 hours. The animal was declared deceased shortly afterwards. Celox Rapid gauze maintained haemostasis in extended use in this limited single animal model. Post mortem examination revealed a stable clot at the site of the arteriotomy with no evidence of re-bleeding.

Conclusion

Celox Rapid was effective at achieving initial homeostasis and preventing re-bleeding in this limited study using a single anaesthetised swine. Its potential for use in situations where evacuation and definitive care may be delayed should be explored.

Identification of new quorum sensing autoinducer binding partners in Pseudomonas aeruginosa using photoaffinity probes

Many bacterial species, including the human pathogen Pseudomonas aeruginosa, employ a mechanism of intercellular communication known as quorum sensing (QS), which is mediated by signalling molecules termed autoinducers. The Pseudomonas Quinolone Signal (PQS) and 2-Heptyl-3H-4-Quinolone (HHQ) are autoinducers in P. aeruginosa, and they are considered important factors in the progress of infections by this clinically relevant organism. Herein, we report the development of HHQ and PQS photoaffinity-based probes for chemical proteomic studies. Application of these probes led to the identification of previously unsuspected putative HHQ and PQS binders, thereby providing new insights into QS at a proteomic level and revealing potential new small molecule targets for virulence attenuation strategies. Notably, we found evidence that PQS binds RhlR, the cognate receptor in the Rhl QS sub-system of P. aeruginosa. This is the first indication of interaction between the Rhl and PQS systems at the protein/ligand level, which suggests that RhlR should be considered a highly attractive target for antivirulence strategies.

Impact of Azithromycin on the Quorum Sensing-Controlled Proteome of Pseudomonas aeruginosa

The macrolide antibiotic, azithromycin (AZM), has been reported to improve the clinical outcome of cystic fibrosis patients, many of whom are chronically-infected with Pseudomonas aeruginosa. However, the highest clinically-achievable concentrations of this drug are well-below the minimum inhibitory concentration for P. aeruginosa, raising the question of why AZM exhibits therapeutic activity. One possibility that has been raised by earlier studies is that AZM inhibits quorum sensing (QS) by P. aeruginosa. To explicitly test this hypothesis the changes brought about by AZM treatment need to be compared with those associated with specific QS mutants grown alongside in the same growth medium, but this has not been done. In this work, we used quantitative 2D-difference gel electrophoresis and 1H-NMR spectroscopy footprint analysis to examine whether a range of clinically-relevant AZM concentrations elicited proteomic and metabolomic changes in wild-type cultures that were similar to those seen in cultures of defined QS mutants. Consistent with earlier reports, over half of the AZM-induced spot changes on the 2D gels were found to affect QS-regulated proteins. However, AZM modulated very few protein spots overall (compared with QS) and collectively, these modulated proteins comprised only a small fraction (12-13%) of the global QS regulon. We conclude that AZM perturbs a sub-regulon of the QS system but does not block QS per se. Reinforcing this notion, we further show that AZM is capable of attenuating virulence factor production in another Gram-negative species that secretes copious quantities of exoenzymes (Serratia marcescens), even in the absence of a functional QS system.

A new Pseudomonas quinolone signal (PQS) binding partner: MexG

Pseudomonas Quinolone Signal (PQS) probes capture a new binding partner for this signal molecule.

The opportunistic pathogen Pseudomonas aeruginosa utilises the cell–cell signalling mechanism known as quorum sensing to regulate virulence. P. aeruginosa produces two quinolone-based quorum sensing signalling molecules; the Pseudomonas quinolone signal (PQS) and its biosynthetic precursor 2-heptyl-4(1H)-quinolone (HHQ). To date, only one receptor (the PqsR protein) has been identified that is capable of binding PQS and HHQ. Here, we report on the synthesis of PQS and HHQ affinity probes for chemical proteomic studies. The PQS affinity probe very effectively captured PqsR in vitro. In addition, we also identified an interaction between PQS and the “orphan” RND efflux pump protein, MexG. The PQS–MexG interaction was further confirmed by purifying MexG and characterizing its ability to bind PQS and HHQ in vitro. Our findings suggest that PQS may have multiple binding partners in the cell and provide important new tools for studying quinolone signalling in P. aeruginosa and other organisms.