Predictors of extended length of stay after unicompartmental knee arthroplasty

PURPOSE

To identify factors that independently predict extended length of stay after unicompartmental knee arthroplasty (UKA) surgery (defined as length of stay longer than 3 days), and to identify factors predicting early post-operative complications.

METHODS

A retrospective analysis of all patients undergoing UKA from January 2016-January 2019 at our institution was performed. Clinical notes were reviewed to determine the following information: Patient age (years), gender, American Society of Anesthesiologists (ASA) grade, weight (kg), height (meters), body mass index (BMI), co-morbidities, indication for surgery, surgeon, surgical volume, surgical technique (navigated or patient-specific instrumentation), implant manufacturer, estimated blood loss (ml), application of tourniquet during the surgery, application of drain, hospital length of stay (days) and surgical complications.

RESULTS

Multivariate regression analysis showed that ASA 3-4 vs. ASA 1-2 [OR 4.4 (CI; 1.8-10.8, p = 0.001)] and a history of cardiovascular disease [OR 2.8 (CI; 1.4-5.5), p = 0.004)] were significant independent predictors of prolonged length of stay. Hosmer-Lemeshow goodness of fit of the model showed a p-value of 0.214. Nagelkerke R-Square was 0.2. For complications, multivariate regression analysis showed that ASA 3-4 vs. ASA 1-2 [OR 5.8 (CI; 1.7-20.7)] and high BMI (BMI >30) [OR 4.3 (CI; 1.1-17.1)] were significant independent predictors of complications. Hosmer-Lemeshow goodness of fit was 0.89 and Nagelkerke R-Square was 0.2. Patients treated with robotics (Navio) techniques had shorter length of stay median 51 h (IQR; 29-96) when compared to other techniques 72 h (IQR; 52-96), p = 0.008.

CONCLUSION

Based on the results of our study, high ASA grade (≥3) appears to be the most important factor excluding eligibility for fast-track UKA. Any number of co-morbidities may increase ASA, but in and of themselves, apart from a history of cardiovascular disease, they should not be seen as contraindications. Appropriate patient selection, technical tools and details during the surgery could facilitate fast track surgery.

Food-Borne Bacteria Associated with Seafoods: A Brief Review

Consumption of contaminated seafoods is a major cause of death and hospitalization particularly in poor and developing countries. As with other food types, seafoods are also not free of food-borne pathogens and several risk factors are associated with its consumption. Regarding seafoods, there are regulatory hygienic alerts in importing countries. This paper briefly reviews the occurrence of seafood-borne diseases and describes the most important bacterial causes of these infections. Also, major bacterial threats, the route of infection, and food safety concerns associated with seafoods consumption are explained. Several bacterial pathogens, like Vibrio spp., Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, Clostridium botulinum, Shigella spp., and Aeromonas spp. are considered as microbiological hazards for seafoods. These bacteria can contaminate seafood products anytime from farm to table. Some effective methods should be adopted for control and prevention of bacterial hazards in fish industry. Maintaining the microbiological water quality of domestic capture, post-harvest care, proper hygiene, etc. can minimize the bacterial hazards. Food-borne intoxications can be controlled by the proper refrigeration of seafoods and the continuous monitoring of the chill chain during the entire production process right up to consumption. Other ways to prevent food-borne outbreaks due to consumptions of seafoods are training of the consumers about correct handling of food, proper preparation, and storage of seafoods.

Functionalized single-walled carbon-nanotube-blended P3HT-based high performance memory behavior thin-film transistor devices

We report on the fabrication and transport properties of single-walled carbon nanotubes (SWCNT) blended with P3HT (poly 3-hexyl thiophene-2, 5-diyl). The composite is used as a hybrid organic active channel transistor. The performances of the fabricated devices were investigated as a function of the SWCNTs' loads in the composite, and their response evaluated under white light illumination. Our results show that for SWCNT loads ≤1.5 wt%, all the devices behave as p-type transistors, exhibiting excellent performance, with an I _on /I _off ratio of 10⁴ and a maximum on-state current (I _on) exceeding 80 μA. Moreover, compared with pristine transistors with a P3HT channel, the Hall mobility of these hybrid TFTs was found to increase by more than one order of magnitude, i.e. increasing from 0.062 to 1.54 cm² V^-1 s^-1. Finally, under light illumination, the transfer characteristics (i.e. I _DS as a function of V _GS) were found to systematically undergo a typical shift together with a fully-reversible memory behavior. A fundamental understanding of this work can assist in providing new routes for the development of reliable efficient hybrid organic-based optoelectronic devices.

HMGA2 is regulated by LIN28 and BRCA1 in human placental cells

The chromatin associated transcription factor HMGA2 is a downstream target of let-7 miRNAs and binds to chromatin to regulate gene expression. Inhibition of let-7 miRNAs by RNA-binding proteins LIN28A and LIN28B is necessary during early embryogenesis to ensure stable expression of HMGA2. In addition to LIN28, HMGA2 is regulated by a BRCA1/ZNF350/CtIP repressor complex. In normal tissues, the BRCA1/ZNF350/CtIP complex binds to the HMGA2 promoter to prevent transcription. However, in many cancers the oncomiR miR-182 targets BRCA1, preventing BRCA1 translation and allowing for increased HMGA2. Little is known about the regulation of HMGA2 during early placental development; therefore, we hypothesized that both LIN28 and BRCA1 can regulate HMGA2 in placental cells. Using siRNA and CRISPR gene editing techniques, we found that knockdowns of both LIN28A and LIN28B increase HMGA2 levels in ACH-3P cells. These cells also demonstrated deficiencies in cell differentiation, seemingly differentiating solely towards the syncytiotrophoblast sublineage, secreting higher amounts of hCG, and displaying upregulated ERVW-1. Additionally, we found that a knockout of both LIN28A and LIN28B caused a significant increase of miR-182 and a decrease in BRCA1 allowing HMGA2 mRNA levels to increase and protein levels to remain the same. Using chromatin immunoprecipitation, we saw binding of the BRCA1 repressor complex to HMGA2. We also saw a decrease in binding to HMGA2's promoter in the LIN28A/B knockout cells. These findings suggest a novel role for BRCA1 during early human placental development.

'Oxygen Level in a Tissue' - What Do Available Measurements Really Report?

The aim of the paper is to discuss what currently is feasible clinically to measure the level of oxygen and how that measurement can be clinically useful. Because oxygen in tissues is quite heterogeneous and all methods of measurement can only provide an average across heterogeneities at some spatial and temporal resolution, the values that are obtained may have limitations on their clinical utility. However, even if such limitations are significant, if one utilizes repeated measurements and focuses on changes in the measured levels, rather than 'absolute levels', it may be possible to obtain very useful clinical information. While these considerations are especially pertinent in cancer, they also pertain to most other types of pathology.

2'-5'-Oligoadenylate synthetase-like protein inhibits intracellular M. tuberculosis replication and promotes proinflammatory cytokine secretion

Host cytoplasmic surveillance pathways are known to elicit type I interferon (IFN) responses which are crucial to antimicrobial defense mechanisms. Oligoadenylate synthetase-like (OASL) protein has been extensively characterized as a part of the anti-viral mechanism, however a number of transcriptomic studies reveal its upregulation in response to infection with a wide variety of intracellular bacterial pathogens. To date, there is no evidence documenting the role (if any) of OASL during mycobacterium tuberculosis infection. Using two pathogenic strains differing in virulence only, as well as the non-pathogenic M. bovis BCG strain, we observed that pathogenicity and virulence strongly induced OASL expression after 24 h of infection. Further, we observed that OASL knock down led to a significant increase in M. tb CFU counts 96 h post-infection in comparison to the respective controls. Luminex revealed that OASL silencing significantly decreased IL-1β, TNF-α and MCP-1 secretion in THP-1 cells and had no effect on IL-10 secretion. We therefore postulate that OASL regulates pro-inflammatory mediators such as cytokines and chemokines which suppress intracellular mycobacterial growth and survival.

Addition of docetaxel to hormonal therapy in low- and high-burden metastatic hormone sensitive prostate cancer: long-term survival results from the STAMPEDE trial

BACKGROUND

STAMPEDE has previously reported that the use of upfront docetaxel improved overall survival (OS) for metastatic hormone naïve prostate cancer patients starting long-term androgen deprivation therapy. We report on long-term outcomes stratified by metastatic burden for M1 patients.

METHODS

We randomly allocated patients in 2 : 1 ratio to standard-of-care (SOC; control group) or SOC + docetaxel. Metastatic disease burden was categorised using retrospectively-collected baseline staging scans where available. Analysis used Cox regression models, adjusted for stratification factors, with emphasis on restricted mean survival time where hazards were non-proportional.

RESULTS

Between 05 October 2005 and 31 March 2013, 1086 M1 patients were randomised to receive SOC (n = 724) or SOC + docetaxel (n = 362). Metastatic burden was assessable for 830/1086 (76%) patients; 362 (44%) had low and 468 (56%) high metastatic burden. Median follow-up was 78.2 months. There were 494 deaths on SOC (41% more than the previous report). There was good evidence of benefit of docetaxel over SOC on OS (HR = 0.81, 95% CI 0.69-0.95, P = 0.009) with no evidence of heterogeneity of docetaxel effect between metastatic burden sub-groups (interaction P = 0.827). Analysis of other outcomes found evidence of benefit for docetaxel over SOC in failure-free survival (HR = 0.66, 95% CI 0.57-0.76, P < 0.001) and progression-free survival (HR = 0.69, 95% CI 0.59-0.81, P < 0.001) with no evidence of heterogeneity of docetaxel effect between metastatic burden sub-groups (interaction P > 0.5 in each case). There was no evidence that docetaxel resulted in late toxicity compared with SOC: after 1 year, G3-5 toxicity was reported for 28% SOC and 27% docetaxel (in patients still on follow-up at 1 year without prior progression).

CONCLUSIONS

The clinically significant benefit in survival for upfront docetaxel persists at longer follow-up, with no evidence that benefit differed by metastatic burden. We advocate that upfront docetaxel is considered for metastatic hormone naïve prostate cancer patients regardless of metastatic burden.

Use of Abdominal Binders after a Major Abdominal Surgery: A Randomized Controlled Trial

Objective

To compare the effect of abdominal binder versus no binder after major abdominal surgery and cesarean section on various post-operative recovery parameters.

Materials and methods

This is a randomized controlled trial conducted at the Department of General Surgery and Obstetrics, Civil Hospital, Karachi, Pakistan. All those patients aged ≥18 years having abdominal surgery including elective and emergency abdominal surgery and cesarean sections with American Society of Anesthesiologists Class I-III were included in the study. Randomization was done using the sealed envelope method by the principal investigator. The intervention group wore an abdominal binder postoperatively while the control group did not use it. Mobilization and the pain status of both groups were evaluated on the first, fourth, and seventh days after surgery.

Results

Primary outcome variables were mobility, assessed via 6-minute walk test (6MWT) and postoperative pain, evaluated via visual analogue scale. There was no statistically significant difference in the 6MWT distance before (p = 0.278) and on postoperative day one of the surgery (p = 0.0762). However, the difference was significant on fourth (p < 0.001) and seventh day (p value < 0.001). With regards to the pain status, patients in the binder group reported significantly less postoperative pain on first, fourth, and seventh (p value < 0.001) day compared to the non-binder group.

Conclusion

The use of abdominal binder postoperatively significantly reduced pain and improved mobility in both obstetric and surgery patients.

P347Complications of catheter ablation for atrial fibrillation: a nation-wide study in Australia and New Zealand

Background

It is important to investigate complications of catheter ablation for atrial fibrillation (AF) - an increasingly common procedure - to inform patients and guide efforts to improve procedural quality. However, clinical trials and registries are limited by selection bias, while existing population-based studies either lack nation-wide data, or fail to report post-discharge complications. The timing and impact of these complications are also poorly understood.

Purpose

To obtain unbiased and comprehensive estimates of complications of AF ablations using national data from Australia and New Zealand. We also evaluated the impact of in-hospital complications on the length of stay and assessed the timing of post-discharge complications.

Methods

We included patients aged ≥18 years undergoing catheter ablation with a primary diagnosis of AF between 2010–2015 in all public and most private hospitals in Australia and New Zealand. The primary outcome was the occurrence of major complications in-hospital or up to 30-days after discharge. We identified major complications based on a literature review and expert clinical opinion and defined these using International Classification of Diseases – 10th revision, Australian Modification diagnoses codes and Australian Classification of Health Interventions procedure codes. We determined the impact of in-hospital complications on the length of stay, adjusting for other covariates, by using negative binomial regression, and reported results as incident rate ratio (IRR) and 95% confidence intervals (CI). Time to first post-discharge complication was evaluated using Kaplan Meier survival analysis.

Results

A total of 20,057 AF ablations were included (mean age 62.1±11.6 y, 56.7% ≤65 years old; 29.2% female; median length of stay 1 day). Of these, major complications occurred in 6.3% procedures (4.6% occurring in-hospital and a further 2.0% occurring in the 30-day post discharge). The most common complications were bleeding or haematoma formation and perforation (primarily pericardial effusion), which accounted to 60.3% and 14.3% of all complications, respectively. Rate of procedure-related deaths was 0.1%. Occurrence of an in-hospital complication more than doubled the length of stay (IRR: 2.3, 95% CI 2.2–2.4) with complications requiring cardiac surgery (IRR 4.5, 95% CI 3.2–6.4) and vascular injuries (IRR 3.9, 95% CI 3.1–4.9) having the length of stay prolonged the most (Figure 1A). In the first-week, 67.3% of post-discharge complications had occurred, and this number reached 95% within three-weeks (Figure 1B).

Conclusions

Major complications after AF ablation were common. In-hospital complications doubled the length of stay. Approximately 30% of complications occurred after discharge with the risk highest in the first seven days. Efforts to reduce complications should focus on reducing the incidence of bleeding and pericardial effusions which counted for more than 75% of all complications.

Acknowledgement/Funding

National Heart Foundation of Australia, The Hospital Research Foundation

Chronic stress, depression and personality type in patients with myasthenia gravis

BACKGROUND AND PURPOSE

Stress is a known risk factor for the onset and modulation of disease activity in autoimmune disorders. The aim of this cross-sectional study was to determine any associations between myasthenia gravis (MG) severity and chronic stress, depression and personality type.

METHODS

In all, 179 consecutive adult patients with confirmed MG attending the Neuromuscular Clinic between March 2017 and December 2017 were included. At baseline, patients were assessed clinically and they completed self-administered scales for disease severity, perceived stress, depression and personality type.

RESULTS

Higher disease severity [Myasthenia Gravis Impairment Index (MGII)] showed a moderate correlation with depression score (Beck's Depression Inventory, Second Edition, r = 0.52, P < 0.001) and a lower correlation with chronic stress (Trier Inventory for Assessment of Chronic Stress, r = 0.28, P = 0.001). Chronic stress scores were different according to personality types (anova, P = 0.02). The linear regression model with MGII score as the dependent variable showed R² = 0.34, likelihood ratio chi-squared 74.55, with P < 0.0001. The only variables that predicted disease severity were depression scores (P < 0.0001) and female sex (P = 0.003).

CONCLUSIONS

A significant association of MG severity with depression and chronic stress was found, as well as with female gender. These findings should raise awareness that the long-term management of MG should address depression and potential stress and consider behavioural management to prevent stress-related immune imbalance.

Cochrane's Linked Data Project: How it Can Advance our Understanding of Surrogate Endpoints

Cochrane has developed a linked data infrastructure to make the evidence and data from its rich repositories more discoverable to facilitate evidence-based health decision-making. These annotated resources can enhance the study and understanding of biomarkers and surrogate endpoints.

First Measurement of Near-Threshold J/ψ Exclusive Photoproduction off the Proton

We report on the measurement of the γp→J/ψp cross section from E_{γ}=11.8  GeV down to the threshold at 8.2 GeV using a tagged photon beam with the GlueX experiment. We find that the total cross section falls toward the threshold less steeply than expected from two-gluon exchange models. The differential cross section dσ/dt has an exponential slope of 1.67±0.39  GeV^{-2} at 10.7 GeV average energy. The LHCb pentaquark candidates P_{c}^{+} can be produced in the s channel of this reaction. We see no evidence for them and set model-dependent upper limits on their branching fractions B(P_{c}^{+}→J/ψp) and cross sections σ(γp→P_{c}^{+})×B(P_{c}^{+}→J/ψp).

Mechanical loading inhibits cartilage inflammatory signalling via an HDAC6 and IFT-dependent mechanism regulating primary cilia elongation

OBJECTIVE

Physiological mechanical loading reduces inflammatory signalling in numerous cell types including articular chondrocytes however the mechanism responsible remains unclear. This study investigates the role of chondrocyte primary cilia and associated intraflagellar transport (IFT) in the mechanical regulation of interleukin-1β (IL-1β) signalling.

DESIGN

Isolated chondrocytes and cartilage explants were subjected to cyclic mechanical loading in the presence and absence of the cytokine IL-1β. Nitric oxide (NO) and prostaglandin E₂ (PGE₂) release were used to monitor IL-1β signalling whilst Sulphated glycosaminoglycan (sGAG) release provided measurement of cartilage degradation. Measurements were made of HDAC6 activity and tubulin polymerisation and acetylation. Effects on primary cilia were monitored by confocal and super resolution microscopy. Involvement of IFT was analysed using ORPK cells with hypomorphic mutation of IFT88.

RESULTS

Mechanical loading suppressed NO and PGE₂ release and prevented cartilage degradation. Loading activated HDAC6 and disrupted tubulin acetylation and cilia elongation induced by IL-1β. HDAC6 inhibition with tubacin blocked the anti-inflammatory effects of loading and restored tubulin acetylation and cilia elongation. Hypomorphic mutation of IFT88 reduced IL-1β signalling and abolished the anti-inflammatory effects of loading indicating the mechanism is IFT-dependent. Loading reduced the pool of non-polymerised tubulin which was replicated by taxol which also mimicked the anti-inflammatory effects of mechanical loading and prevented cilia elongation.

CONCLUSIONS

This study reveals that mechanical loading suppresses inflammatory signalling, partially dependent on IFT, by activation of HDAC6 and post transcriptional modulation of tubulin.

Detection and characterization of multidrug-resistant Salmonella enterica serovar Infantis as an emerging threat in poultry farms of Faisalabad, Pakistan

AIMS

The aim of this study was the molecular identification of Salmonella enterica serovar Infantis (S. Infantis) isolated from poultry samples and their antimicrobial resistance and virulence profiling.

METHODS AND RESULTS

A total of 149 isolates, belonging to genus Salmonella, originally isolated from 340 suspected poultry post mortem specimens reported by us earlier were preliminary identified as Salmonella by biochemical methods and confirmed by polymerase chain reaction targeting genus-specific gene invA. Targeting serovar-specific gene fragment (fljB) resulted in confirmation of 54 isolates as S. Infantis which were further confirmed by sequencing of 16S RNA and fljB genes. Swimming and swarming motilities were detected in 98·1 and 11·1% isolates respectively. Phenotypic disc diffusion assay against 23 antimicrobial agents showed the highest resistance against pefloxacin (PEF) (94·4%), chloramphenicol (83·3%) and imipenem (77·7%) while 5·3% isolates showed extended-spectrum β-lactamase production. Fifty-nine genes reported for antimicrobial resistance and 12 for conferring virulence were targeted. The most prevalent resistance gene for aminoglycosides was aadA (42·3%), for quinolone resistance determining region parE (62·5%), for penicillin's Int1 (62·9%), for chloramphenicol cat3 (66·1%) and for beta-lactams bla_{TEM -1} (44·4%). Among efflux pump coding genes, armA showed highest (74·2%) prevalence and for virulence, a high prevalence of SopE (89·2%) showed the zoonotic potential of the isolates. The activity of efflux pumps was detected through Ethidium Bromide-agar method.

CONCLUSIONS

Poultry could act as reservoirs of multidrug resistance Salmonella.

SIGNIFICANCE AND IMPACT OF THE STUDY

We firstly report the prevalence and molecular characterization of virulence/drug resistance in S. Infantis from this region and the results may contribute to designing precisely targeted therapy. This study has also highlighted the possible emergence of S. Infantis with zoonotic potential.

Reference ranges for D-dimer levels in Malaysian women in the three trimesters of pregnancy

INTRODUCTION

Plasma D-dimer levels rise progressively during pregnancy, so one cannot apply normal reference ranges, or the usual cut-off value (500ng/mL), for the exclusion of venous thromboembolism (VTE), in pregnant women. This study was carried out in pregnant Malaysian women in order to build applicable reference ranges for D-dimer.

MATERIALS AND METHODS

A cross-sectional study was conducted to measure D-dimer in healthy pregnant women, and a non-pregnant control group, using the quantitative HaemosIL D-dimer HS500 assay. Reference ranges were derived using CLSI 'Robust' methods, and differences between group medians were tested using the Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

Plasma D-dimer levels were measured in 92 pregnant women (distributed across the three trimesters)and 31 control women. The medians (and reference ranges) in ng/mL were: control 265 (<799); first trimester 481 (<1070); second trimester 1073 (357-1748); 3rd trimester 1533 (771-2410). There were significant differences between the D-dimer levels of each group and each of the other groups (P<0.001).

CONCLUSIONS

Reference ranges for D-dimer in pregnant Malaysian women have been establised by this study. Whether these ranges can be used to determine cut-off levels for the exclusion of VTE at different stages of pregnancy is doubtful, as the levels rise continuously through pregnancy, and some very high outlying values occur in apparently normal near-term pregnancy.

Surgical intervention for intestinal typhoid perforation

AIM

Typhoid perforation is the most fatal complication of typhoid fever in developing countries and is most often caused by the bacteria Salmonella Typhi. There are conflicting views as to which type of surgical intervention gives the best outcome. The aim of this study was to determine the mortality associated with the different types of surgical interventions employed in patients with typhoid perforation.

METHOD

This was a retrospective review of the medical records of adult and paediatric surgical patients treated in the general and paediatric surgical units of the Korle Bu Teaching Hospital. Information was obtained from medical records at the Korle Bu Teaching Hospital in Accra, Ghana, between January 2009 and April 2012. The data was analysed using IBM SPSS Statistics version 20 and 22.

RESULTS

133 patients (median age of 21 years, 72.2% males) with typhoid perforation were included in the study. The typhoid perforation specific mortality rate was 12.8%. Males had a significantly lower mortality rate (7.3%) compared to females (27%). Simple bowel closure (85.7% of total) was the most common surgical intervention performed and patients operated upon with this method had a significantly lower mortality rate (9.6%) compared to patients with bowel resection (31.6%).

CONCLUSIONS

In this study, patients treated with intestinal resection were more likely to die from typhoid perforation and female gender was a risk factor for death. Simple bowel closure was the predominant surgical procedure.

Abstract PD3-10: Higher serum PD-L1 predicts for increased overall survival to lapatinib vs trastuzumab in the phase 3 CCTG MA.31 trial

Background: In the CCTG (Canadian Clinical Trials Group) MA.31 randomized phase 3 trial, the trastuzumab-taxane combination led to longer PFS than lapatinib-taxane in HER2-positive metastatic breast cancer (MBC). We previously reported the prognostic utility of pretreatment serum PD-L1 in the trastuzumab arm of MA.31 (ASCO 2018, #1031), and here we evaluate serum PD-L1 in the lapatinib arm, and in the whole trial. Higher serum PD-L1 has been reported to be associated with reduced response to treatment with the immune checkpoint inhibitors in melanoma and lung cancer.

Methods: MA.31 accrued 652 centrally and/or locally-identified HER2-positivepatients; 186 in the trastuzumab arm, and 202 in the lapatinib armhad pretreatment serum available. TheELLA immunoassay platform (ProteinSimple, San Jose, CA) was used to quantitate serum PD-L1. Step-wise forward Cox multivariate analysis was used for PFS and OS, and testing for treatment-biomarker interaction was based on the local partial-likelihood method (Liu Y, Jiang W, and Chen BE, Statistics in Medicine 34, 3516-3530, 2015).

Results: In the total study population, pretreatment serum PD-L1 concentration had a median of 86.2 pg/ml, and 25% and 75% interquartiles of 64.1 and 134.3 pg/ml, respectively. In univariate analysis in the whole trial, and within both treatment arms, serum PD-L1 was not a significant biomarker for PFS. For OS, higher serum PD-L1 (as a continuous variable) was significant for shorter OS within the trastuzumab arm (HR=3.84, p=0.04), but was not associated with OS in the lapatinib arm (p=0.37). In the whole trial, in multivariate analysis for OS [15 covariates included: age, race, ECOG status, anthracyclines, other chemo, endocrine, radio, other prior adjuvant therapy, disease status, ER status, PR status, Ki67 (log transformed), CK5, EGFR, treatment arm, and serum PD-L1 (with median cut point)], serum PD-L1 remained a significant independent covariate (HR= 2.27, p= 0.001 (Table).There was significant interaction between treatment arm and continuous serum PD-L1 (Bootstrap method, p=0.0025); above 214.2 pg/ml serum PD-L1 (89% percentile), higher pretreatment serum PD-L1 was associated with a shorter OS to trastuzumab treatment, but longer OS to lapatinib treatment.

Conclusions: In the CCTG MA.31 trial, serum PD-L1 was a significant predictive factor: higher pretreatment serum PD-L1 was associated with a shorter OS to trastuzumab treatment, but longer OS to lapatinib treatment. Immune evasion may decrease the effectiveness of trastuzumab therapy. Further evaluation of elevated serum PD-L1 in the advanced breast cancer setting is warranted to identify HER2-positive MBC patients who may benefit from novel immune-targeted therapies in addition to trastuzumab.

Multivariate Analysis (whole trial): Significant Independent CovariatesCovariateP-ValueHRLower 95% CIHigher 95% CISerum PD-L1 (pretreatment) (&gt;median vs &lt;median)0.0012.271.403.68EGFR Status (continuous IHC score)0.0031.0121.0041.019Other Chemotherapy (yes vs no)0.0081.911.193.07Treatment Arm (trastuzumab vs. lapatinib)0.0100.530.330.86ECOG Performance Status (0 vs 1 or 2)0.0250.590.370.94Ki67 (log)0.0461.451.0062.081

Citation Format: Moku PR, Shepherd LE, Ali SM, Leitzel K, Parulekar WE, Zhu L, Virk S, Nomikos D, Aparicio S, Gelmon KA, Drabick JJ, Cream L, Halstead SE, Umstead T, Mckeone D, Maddukuri A, Polimera HV, Ali A, Poulose J, Pancholy N, Spiegel H, Nagabhairu V, Chen BE, Lipton A. Higher serum PD-L1 predicts for increased overall survival to lapatinib vs trastuzumab in the phase 3 CCTG MA.31 trial [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 PD3-10.