Blinded Studies Research Articles

Designs for Vaccine Studies

Due to dependent happenings, vaccines can have different effects in populations. In addition to direct protective effects in the vaccinated, vaccination in a population can have indirect effects in the unvaccinated individuals. Vaccination can also reduce person-to-person transmission to vaccinated individuals or from vaccinated individuals compared with unvaccinated individuals. Design of vaccine studies has a history extending back over a century. Emerging infectious diseases, such as the SARS-CoV-2 pandemic and the Ebola outbreak in West Africa, have stimulated new interest in vaccine studies. We focus on some recent developments, such as target trial emulation, test-negative design, and regression discontinuity design. Methods for evaluating durability of vaccine effects were developed in the context of both blinded and unblinded placebo crossover studies. The case-ascertained design is used to assess the transmission effects of vaccines. The novel ring vaccination trial design was first used in the Ebola outbreak in West Africa.

Incidence of blindness in open-angle glaucoma in Sweden: a long-term follow-up study

Background: Open-angle glaucoma (OAG) is a leading cause of irreversible blindness. There are no prospective studies on the risk of developing blindness in both eyes in individuals with definite OAG. Methods: A total of 354 patients with newly diagnosed OAG, who had participated in four studies conducted at the Eye Department in Tierp, Sweden, from 1979 to 2006, were included in the investigation. Using the World Health Organization’s criteria for blindness, medical records, glaucoma case records, and visual fields were reviewed to identify patients who developed bilateral blindness. Incidence proportions and incidence rates were estimated. To assess potential risk factors for blindness, standardised morbidity ratios (SMRs) were calculated. The effects of age and sex were also analysed using Cox proportional hazard models. Results: By the end of the study in August 2023, 33 cases of blindness caused by OAG had been found, corresponding to an incidence proportion of 9.3% (95% confidence interval [CI]: 6.5–12.8%). Within the first 20 years, 29 cases were detected, yielding a proportion of 8.2% (95% CI: 5.5–11.6%). The incidence rate was estimated to be 8.6 per 1,000 person-years (95% CI: 5.9–12.6 per 1,000 person-years). Glaucoma-related blindness was associated with male sex (SMR 2.33; 95% CI: 1.13–4.80). The hazard ratio was doubled for every 5 year of increasing age (2.21; 95% CI: 1.60–3.05). Conclusion: In this study of blindness in newly diagnosed OAG in a Swedish population, approximately one in 10 patients progressed to bilateral blindness caused by the disease. Old age and male sex were identified as significant risk factors.

Pregabalin as an Effective Adjunct in Postoperative Care following Third Molar Removal

Background: The surgical removal of impacted mandibular third molar is probably the most commonly performed procedure in oral & maxillofacial surgery. This study aimed to evaluate the effectiveness of pregabalin as an adjunct to standard analgesia for managing postoperative pain, facial swelling, and trismus following mandibular third molar extraction.  Methods: A total of 136 patients undergoing bilateral extractions were included. Each patient served as their own control, receiving pregabalin with standard analgesia for one extraction and only standard analgesia for the other. Postoperative pain was assessed using the Visual Analogue Scale (VAS) at various intervals, while facial swelling and interincisal distance (IID) were measured on Days 1, 3, 7, and 14.  Results: VAS scores were higher in the control group; however, it was not statistically significant (P = 0.000) at any time interval. % facial swelling was significantly lower in the test group on postoperative day 1[2.32(1.77- 2.95) test; 2.32 (1.82-3.60) control; P = 0.009] and day 3 [6.67 (5.17-8.44) test; 7.49 (5.77-9.43) control; P = 0.004]. However, no significant differences were seen on postoperative day 7 and day 14. Similarly, no significant differences in mouth opening measurements were found.  Conclusion: Pregabalin is effective as an adjuvant therapy in reducing pain and facial swelling after third molar surgery. However, multicenter, randomized, double- blinded studies are recommended to confirm these findings.

Botulinum Toxin Treatment of Psoriasis-A Comprehensive Review.

A literature search on the subject of botulinum toxin treatment in psoriasis found 15 relevant articles, 11 on human subjects and 4 on animal studies. Of the human data, eight were clinical trials and three were single case reports. Seven out of eight clinical trials, all open-label, reported improvement in psoriasis following intradermal or subcutaneous botulinum toxin injections. One double-blind, placebo-controlled study, which used a smaller dose than the open-label studies, did not note a healing effect. Animal studies have shown that injection of botulinum toxins in the skin heals psoriatic skin lesions and can reduce the level of interleukins (ILs) and cytokines as well as inflammatory cells in psoriatic plaques. There is a need for controlled, blinded studies conducted in larger numbers of patients with doses that have shown promise in open-label studies.

Participation in Non-small Cell Lung Cancer Clinical Trials in the United States by Race/Ethnicity

IntroductionDespite efforts by Cancer Centers and community organizations to increase diversity in clinical trials, significant racial/ethnic disparities remain. Given the high mortality rates in non-small cell lung cancer (NSCLC), it is important to increase diversity in NSCLC trials, ensuring all patients benefit from advances in new treatment modalities. Materials and MethodsWe evaluated the distribution of racial/ethnic minority enrollment in NSCLC clinical trials using data from ClinicalTrials.gov. We extracted trial characteristics, including start year, study phase, tumor stage, sample size, sponsor, geographic region, and masking. The number of participants by race/ethnicity was obtained from ClinicalTrials.gov or linked publications. Using annual NSCLC incidence data from SEER*Stat for each racial/ethnic group from 2010 to 2019, we applied a 2-sample test for equality of proportions with continuity correction to assess differences between incidence and trial participation. ResultsA total of 147 unique studies were included in the final analysis. Of the 28,540 participants, 79.6% were White, with 3% Black, 10.4% Asian or Pacific Islander and 3.4% Hispanic/Latino. Most participants were enrolled in phase III trials (63.8%), industry-sponsored (93.9%), and open-label (67.7%). Black patients were more commonly enrolled in academic sponsored trials and less commonly enrolled in masked (i.e., blinded) studies. When comparing trial participation to annual incidence data, we observed underrepresentation among Black participants (Difference: −7.9%) and Hispanic/Latino participants (Difference: −3.2%). ConclusionPersistent underrepresentation exists in NSCLC clinical trials among Black and Hispanic/Latino patients. We urge further investigation of these findings through well-designed clinical trials among diverse patient populations.

Review: Food-induced mucosal alterations visualized using endomicroscopy.

Confocal laser endomicroscopy (CLE) is a novel technique allowing real time invivo microscopy during standard endoscopy. Recently, acute mucosal alterations after food administration visualized by CLE have been linked to symptoms in irritable bowel syndrome (IBS). Interestingly, the observed reactions occurred in subjects without demonstrable allergic sensitization to food-this is in line with mechanistic research showing local but not systemic allergic sensitization to foods in an animal model for IBS. Here, European experts conducting CLE with food administration provide a narrative review of the available literature and propose practical guidance on the use of this technique. CLE allows physicians to observe acute mucosal reactions after the application of food to the duodenal mucosa in patients with functional gastrointestinal disorders. Some open-label interventions show a symptomatic benefit when patients exclude the nutrient that triggered an acute mucosal reaction. However, many technical, mechanistic, and clinical questions remain unanswered to date. Technically, the interobserver variability and learning curve requires systematic evaluation and criteria or cutoffs for alterations require validation. Mechanistic studies are needed to enhance our understanding of the mechanisms underlying observed alterations. Finally, rigorous blinded controlled studies are needed to assess a link of these observed alterations with symptom generation. CLE offers a platform allowing scientific insights related to food induced acute mucosal alterations. However, many questions remain unanswered, and more research is warranted to understand the role of acute mucosal alterations visualized upon food administration in IBS pathophysiology and treatment.

Comparison of Product Features and Clinical Trial Designs for the DTx Products with the Indication of Insomnia Authorized by Regulatory Authorities

BackgroundDigital therapeutics (DTx) have attracted attention as the substitutes or add-ons to conventional pharmacotherapy and the number of DTx products authorized with the regulatory reviews of the clinical evidence is increasing. Insomnia is one of the major targets of the DTx due to the benefit from cognitive behavioral interventions and several products have been launched in the market with regulatory reviews. However, common features of the products and the clinical evidence required by each regulatory agency have not been investigated.MethodsIn this study, we identified the DTx products with the primary indication of insomnia authorized with regulatory reviews of clinical evidence by literature and website searches, and investigated the common features of the products and of the study designs for the pivotal clinical trials.ResultsThe total of 6 DTx products were identified. The components of cognitive behavioral therapy for insomnia (CBT-I) were identified as common features of the products. All the pivotal clinical trials were randomized, parallel-group, blind studies against insomnia patients. No products have been authorized in multiple countries regardless of the similarity of the features of the products and of the study designs for the pivotal clinical trials.ConclusionsOur study revealed that the components of CBT-I and gold standard design in pivotal clinical trials were adopted in all the DTx products for insomnia authorized with reviews of clinical evidence. At the same time, our findings suggest the needs of internationally harmonized regulatory review and authorization system to facilitate the early patient access to the promising DTx products.

Sensitivity and specificity of the sensory collapse test for nerve entrapment syndrome in the upper extremity

ObjectivesSeveral prospective blinded studies have found poorer sensitivity for the sensory collapse test than reported by Susan E Mackinnon’s team. However, the blinded examiner had no knowledge of the patient's clinical presentation, or even of the purpose of the test. In these conditions, it seems difficult to perform the sensory collapse test correctly. The aim of the present study was to evaluate the efficacy of the sensory collapse test in the diagnosis of nerve compression in the upper extremity, using a trained, “partially” blinded examiner, with a minimum of clinical information in order to avoid bias due to poor execution of the test, while still unable to influence the test result. MethodsSeventy-two patients with diagnosis of nerve entrapment in the upper extremity were included prospectively. The sensory collapse test was performed by two examiners, one of whom was blinded to laterality and to the site of nerve compression, aware only of the affected nerve. Using electrodiagnosis study as reference, the sensitivity and specificity of the sensory collapse test were calculated for each examiner. ResultsThe unblinded examiner showed 72% sensitivity and 57% specificity, and the blinded 68% sensitivity and 57% specificity. ConclusionsThe sensory collapse test is useful for diagnosis of nerve entrapment in the upper limb, even with a blinded examiner. Level of evidence3.

Platelet rich plasma injection in knee osteoarthritis: results after four years.

Background Knee osteoarthritis (KOA) is a progressive degenerative disease and a leading cause of disability worldwide. Intra-articular injection of platelet-rich plasma (PRP) is still a debatable symptomatic treatment and has provided multiple publications in literature with mixed results. Aim of the work To evaluate the short and long term effects of intra-articular injection of PRP on pain and functional status of the knee joint as measured by the Lysholm questionnaire and visual analogic pain scale (VAS). Patients and methods Twenty-one patients with primary Kellgren-Lawrence grade 3 KOA were assessed using the Lysholm questionnaire and the visual analogue scale for pain (VAS). A single PRP injection was administered, followed by reassessment of VAS at the first, fourth and eighth weeks after the injection. After eight weeks, patients were assessed with VAS and Lysholm questionnaire. In order to evaluate the long term effect of this single injection, we reassessed the patients four years after the injection using the same method. Results Fifteen females (71%) and six males (29%) with mean age 60 years (ranging from 44 to 76 years) were enrolled. After a single PRP injection, there was significant improvement in Lysholm and VAS. Before the injection, VAS medium score was 7 (ranging from 5 to 9) and we observed improvements in all assessments at the first (medium VAS 2), fourth (medium VAS 2) and eighth week (medium VAS 2) post injection and was still better than the pre injection score after 4 years (medium VAS 4). This was also observed in Lysholm score. The pre injection score was 41; at 8 weeks, 84; at 4 years, 66. Conclusion PRP injection achieves good results in the symptomatic treatment of Kellgren-Lawrence grade 3 KOA. This study confirmed that a single PRP injection can provide a long-term effect in pain reduction and functional status improvement in KOA, despite the progression of the disease. Further studies with more patients and randomized double blinded controlled studies are recommended to confirm these results.

Diagnostic accuracy of non-invasive cardiac imaging modalities in patients with a history of coronary artery disease: a meta-analysis

BackgroundThe diagnostic performance of non-invasive imaging techniques for detecting obstructive coronary artery disease (CAD) in patients with a history of myocardial infarction or percutaneous coronary intervention has not been comprehensively...

Safety Profile of a Cognitively Unimpaired Older Population with Elevated Cerebral Amyloid in a 4.5-Year Clinical Trial

BackgroundPreclinical Alzheimer’s disease is increasingly studied in clinical trials. Although safety signals are routinely monitored in clinical trial populations with Alzheimer’s disease, it can be challenging to identify new safety signals against background rates of age-related medical comorbidities.ObjectivesTo report detailed safety data from a cognitively unimpaired older population with evidence of elevated cerebral amyloid levels on amyloid positron emission tomography in the placebo arm of a Phase 3 clinical trial.DesignPhase 3, 4.5-year, multicenter, placebo-controlled trial.SettingPlacebo data from the Anti-Amyloid Treatment in Asymptomatic Alzheimer’s Disease (A4) study.ParticipantsEnrolled participants were aged 65–85 years with a global Clinical Dementia Rating score of 0, a Mini-Mental State Examination score of 2–-30, a Wechsler Memory Scale Logical Memory IIa (delayed recall) score of 6–18, and elevated brain amyloid levels on 18F-florbetapir positron emission tomography.MeasurementsStudy participants who received placebo were followed up with post-baseline safety measures. Assessments included review of concomitant medication and adverse events, the Columbia Suicide Severity Rating Scale, electrocardiograms, and neuroimaging (brain magnetic resonance imaging).ResultsIn total, 591 study participants (mean age [standard deviation] 71.9 [5.0] years) were assigned to and received placebo in the A4 study, and were followed up to 240 weeks. Participants were primarily White (93.9%) and from the United States (86.8%); 60.4% were women. The most common serious adverse events (incidence rate per 100 person-years) were pneumonia (incidence rate=0.4; 95% confidence interval=0.2–0.7) and atrial fibrillation (incidence rate=0.4; 95% confidence interval=0.2–0.7). The most common treatment-emergent adverse events were upper respiratory tract infection (incidence rate=10.9; 95% confidence interval=9.4–12.5), fall (incidence rate=7.7; 95% confidence interval=6.6–9.0), and nasopharyngitis (incidence rate=5.8; 95% confidence interval=4.8–6.9). The most common ischemia-related findings on magnetic resonance imaging were subcortical infarction (incidence rate=1.4; 95% confidence interval=1.0–2.0) and acute ischemia (incidence rate=0.6; 95% confidence interval=0.3–1.0). Emergent amyloid-related imaging abnormalities with hemosiderin deposition occurred in 32.8% of participants who received placebo; the primary factor associated with these events during the post-baseline period was the number of microhemorrhages at baseline (odds ratio=349.9; 95% confidence interval=247.6–494.4; adjusted p<0.001).ConclusionSafety findings in the placebo-treated group from the A4 study provide a robust characterization of expected safety in a clinical trial population with preclinical Alzheimer’s disease. These results may provide context in planning future studies and safety evaluations during ongoing blinded studies in preclinical Alzheimer’s disease.

Dans la peau d’un aveugle – l’étrange cécité de John Howard Griffin. Deuxième partie : guérison. Diagnostic

Given the lack of available medical records, any study of John Howard Griffin's blindness must rely on Griffin's own words and that of his biographers. Griffin's account of his blindness has generally been accepted, even though some of his friends privately expressed doubts as to its genuineness. After reviewing various sources, we conclude that Griffin's blindness was a pseudo-blindness that is a combination of “functional disorder” and outright simulation. We will further enquire into the possibility that Griffin experienced a miraculous healing – an explanation that he personally rejected – by briefly examining the well-publicized cases of two 20th Century Catholic holy women. We will then lay the groundwork for a psychological explanation of Griffin's blindness, concluding that it had two functions: an escapist one, which allowed him to avoid embarrassment, and a promotional one, which helped him market his novels.

Carboxylesterase Activatable Molecular Probe for Personalized Treatment Guidance by Analyte-Induced Molecular Transformation.

Accurate visualization of tumor microenvironment is of great significance for personalized medicine. Here, we develop a near-infrared (NIR) fluorescence/photoacoustic (FL/PA) dual-mode molecular probe (denoted as NIR-CE) for distinguishing tumors based on carboxylesterase (CE) level by an analyte-induced molecular transformation (AIMT) strategy. The recognition moiety for CE activity is the acetyl unit of NIR-CE, generating the pre-product, NIR-CE-OH, which undergoes spontaneous hydrogen atom exchange between the nitrogen atoms in the indole group and the phenol hydroxyl group, eventually transforming into NIR-CE-H. In cellular experiments and in vivo blind studies, the human hepatoma cells and tumors with high level of CE were successfully distinguished by both NIR FL and PA imaging. Our findings provide a new molecular imaging strategy for personalized treatment guidance.

Carboxylesterase Activatable Molecular Probe for Personalized Treatment Guidance by Analyte‐Induced Molecular Transformation

AbstractAccurate visualization of tumor microenvironment is of great significance for personalized medicine. Here, we develop a near‐infrared (NIR) fluorescence/photoacoustic (FL/PA) dual‐mode molecular probe (denoted as NIR−CE) for distinguishing tumors based on carboxylesterase (CE) level by an analyte‐induced molecular transformation (AIMT) strategy. The recognition moiety for CE activity is the acetyl unit of NIR−CE, generating the pre‐product, NIR−CE−OH, which undergoes spontaneous hydrogen atom exchange between the nitrogen atoms in the indole group and the phenol hydroxyl group, eventually transforming into NIR−CE−H. In cellular experiments and in vivo blind studies, the human hepatoma cells and tumors with high level of CE were successfully distinguished by both NIR FL and PA imaging. Our findings provide a new molecular imaging strategy for personalized treatment guidance.

Identifying intraoperative events in a simulated laparotomy video: a multinational study of inattentional blindness among anesthesiologists.

Medical errors may be occasionally explained by inattentional blindness (IB), i.e., failing to notice an event/object that is in plain sight. We aimed to determine whether age/experience, restfulness/fatigue, and previous exposure to simulation education may affect IB in the anesthetic/surgical setting. In this multicentre/multinational study, a convenience sample of 280 anesthesiologists watched an attention-demanding video of a simulated trauma patient undergoing laparotomy and (independently/anonymously) recorded the abnormalities they noticed. The video contained four expected/common abnormalities (hypotension, tachycardia, hypoxia, hypothermia) and two prominently displayed unexpected/rare events (patient's head movement, leaky central venous line). We analyzed the participants' ability to notice the expected/unexpected events (primary outcome) and the proportion of expected/unexpected events according to age group and prior exposure to simulation education (secondary outcomes). Anesthesiologists across all ages noticed fewer unexpected/rare events than expected/common ones. Overall, younger anesthesiologists missed fewer common events than older participants did (P = 0.02). There was no consistent association between age and perception of unexpected/rare events (P = 0.28), although the youngest cohort (< 30yr) outperformed the other age groups. Prior simulation education did not affect the proportion of misses for the unexpected/rare events but was associated with fewer misses for the expected/common events. Self-perceived restfulness did not impact perception of events. Anesthesiologists noticed fewer unexpected/rare clinical events than expected/common ones in an attention-demanding video of a simulated trauma patient, in keeping with IB. Prior simulation training was associated with an improved ability to notice anticipated/expected events, but did not reduce IB. Our findings may have implications for understanding medical mishaps, and efforts to improve situational awareness, especially in acute perioperative and critical care settings.

Effectiveness of remote pulmonary artery pressure estimating in heart failure: systematic review and meta-analysis

Heart failure (HF) poses a significant challenge, often leading to frequent hospitalizations and compromised quality of life. Continuous pulmonary artery pressure (PAP) monitoring offers a surrogate for congestion status in ambulatory HF care. This meta-analysis examines the efficacy of PAP monitoring devices (CardioMEMS and Chronicle) in preventing adverse outcomes in HF patients, addressing gaps in prior randomized controlled trials (RCTs). Five RCTs (2572 participants) were systematically reviewed. PAP monitoring significantly reduced HF-related hospitalizations (RR 0.72 [95% CI 0.6–0.87], p = 0.0006) and HF events (RR 0.86 [95% CI 0.75–0.99], p = 0.03), with no impact on all-cause or cardiovascular mortality. Subgroup analyses highlighted the significance of CardioMEMS and blinded studies. Meta-regression indicated a correlation between prolonged follow-up and increased reduction in HF hospitalizations. The risk of bias was generally high, with evidence certainty ranging from low to moderate. PAP monitoring devices exhibit promise in diminishing HF hospitalizations and events, especially in CardioMEMS and blinded studies. However, their influence on mortality remains inconclusive. Further research, considering diverse patient populations and intervention strategies with extended follow-up, is crucial for elucidating the optimal role of PAP monitoring in HF management.

Cardiac transplant rejection assessment with 18F-FDG PET-CT: initial single-centre experience for diagnosis and management

BackgroundRejection is a major cause of mortality and morbidity in heart transplant (HTx) recipients. Current methods for diagnosing rejection have limitations. Imaging methods to map the entire left ventricle and reliably identify potential sites of rejection is lacking. Animal studies suggest FDG PET-CT (FDG PET) could have potential application in human HTx recipients.MethodsBetween December 2020 and February 2022, all HTx recipients at Harefield Hospital, London, with definite or suspected rejection underwent FDG PET in addition to routine work-up.ResultsThirty HTx recipients (12 with definite and 18 with suspected rejection) underwent FDG PET scans. Overall, 12 of the 30 patients had FDG PET with increased myocardial avidity, of whom 2 died (17%). Eighteen patients of the 30 patients had FDG PET with no myocardial avidity and all are alive (100%, p = 0.15). All patients with definite rejection, scanned within 2 weeks of starting anti-rejection treatment, showed increased myocardial avidity. In 5 cases, FDG PET showed myocardial avidity beyond 6 weeks despite pulsed steroid treatment, suggesting unresolved myocardial rejection.ConclusionPreliminary findings suggest FDG PET may have a role in diagnosing cardiac transplant rejection. Future blinded studies are needed to help further validate this.

Ultrasonography in the diagnosis of pediatric distal forearm fracture: a systematic review

Purpose: Distal forearm fractures are one of the commonest injuries in children due to falling on an outstretched hand. Plain X-ray is the gold standard test for diagnosing fractures of long bones but it exposes patients to radiation with its associated health hazards. The use of ultrasonography has been proposed as a safer diagnostic test. This review aimed to summarize the evidence regarding the diagnostic accuracy of bedside ultrasonography for identifying distal forearm fractures in pediatric patients. Methods: Electronic search of MEDLINE, EMBASE, Cochrane Library, Google Scholar, and Best Bets databases was conducted for studies published from inception to May 2017. The search terms used included “forearm” and “fractures” and “children.” Results: Seven studies were included in the review. The overall accuracy of ultrasonography ranged from 78.6% to 99.5%. The sensitivity and specificity ranged from 85% to 100%, and from 73% to 100%, respectively. The area under the curve for ultrasonography ranged from 0.79 to 1.00. Conclusion: Ultrasound is a reliable diagnostic tool for the diagnosis of distal forearm fractures in children when performed by well-trained emergency doctors and through using an appropriate viewing method. Conducting larger prospective blinded studies on long bone injuries would be recommended.

The peri / postoperative analgesic effect of intravenous paracetamol in dogs

PICO Question In healthy dogs undergoing a surgical procedure, is there improved pain control in dogs receiving intravenous paracetamol in the peri / postoperative period compared to dogs not receiving intravenous paracetamol? Clinical bottom line Category of research Treatment. Number and type of study designs reviewed Three randomised, controlled, and blinded studies. Two studies directly address the PICO question whereby postoperative pain assessment was clinically evaluated following intravenous (IV) paracetamol. The third study addressed the question to a lesser extent, whereby the impact on the sevoflurane minimum alveolar concentration (MAC) reduction in response to noxious stimuli was assessed following the administration of IV paracetamol. Strength of evidence Weak. Outcomes reported The findings of the first two studies presented appear to directly contradict each other. The first study demonstrated a reduction in pain in all groups and found no differences in analgesia between IV paracetamol and other non-steroidal anti-inflammatories drugs (NSAIDs), while the second study reported no analgesia effects from IV paracetamol and was terminated prematurely because a high number of dogs required rescue analgesia. The first study reported sufficient analgesic effects of IV paracetamol and the second study reported no analgesia effects of IV paracetamol. Both were blinded, randomised, controlled studies and directly addressed the PICO question in relation to the peri / postoperative analgesic effects of IV paracetamol. However, their methods and sample sizes were very different. The third study did not demonstrate a clinically relevant sevoflurane MAC reduction after IV paracetamol in dogs. Conclusion At present, there is limited and weak evidence to suggest that IV paracetamol provides peri / postoperative analgesia in dogs. However, further studies are required to better assess its efficacy, its duration of action, and the appropriate doses that are necessary to reach therapeutic plasma levels. The reduced incidence of side effects at the currently recommended doses could support its peri / postoperative use, where NSAIDs use is contraindicated. How to apply this evidence in practice The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources. Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.

Abstract 4749: Acrivon predictive precision proteomics (AP3) uncovers mechanism of resistance to ACR-368, a clinical-stage CHK1/2 inhibitor, and identifies rational combination treatment

Abstract ACR-368 (prexasertib) is a clinically advanced CHK1/2 inhibitor which has demonstrated durable activity across a proportion of patients with advanced solid tumors. Genomic biomarkers have proven unsuccessful in predicting response to ACR-368, limiting its clinical success. Using AP3, we previously developed a response-predictive proteomics-based test for ACR-368 (ACR-368 OncoSignature) for the identification of patients sensitive to ACR-368 monotherapy treatment as demonstrated in blinded preclinical studies. A Phase 2 clinical trial is ongoing where patients are treated with ACR-368 monotherapy based on OncoSignature-predicted sensitivity (NCT05548296). Here, we demonstrate the utility of AP3 for the identification of a key druggable resistance mechanism to ACR-368 and how to overcome that with low dose gemcitabine (gem), providing OncoSignature negative patients with a new potential therapeutic option. Five ovarian cancer cell lines were rendered durably resistant to ACR-368 by culturing in the presence of clinically relevant concentrations of ACR-368. Matched parental and ACR-368 resistant cell line pairs were profiled using AP3 mass spectrometry. Comprehensive pathway reconstitution and kinase activity analyses were performed to identify drug resistance mechanisms in an unbiased manner. Downregulation of DNA damage repair pathway activity was causally linked to the ACR-368-resistant phenotype, suggesting agents that restore replication stress around the CHK1/2 signaling axis may re-sensitize to ACR-368. To test this, a panel of ovarian cancer cell lines with intrinsic or drug-induced resistance to ACR-368 were screened for cell growth inhibition by ACR-368 combined with gem. Gem synergized with ACR-368 in 12/13 cell lines at low doses (1-40 nM). Moreover, Western blot analysis demonstrated protein markers of replication stress were induced by low dose gem (3-30 nM), suggesting a correlation between gem-induced replication stress and synergy with ACR-368. Comet assays showed that DMSO, gem (3 nM), or ACR-368 (100 nM) had minimal impact (4.4%, 4.5%, and 11.4%, respectively) on % comet tail DNA in ACR-368 resistant cells, while the gem combination led to 35% comet tail DNA (p&amp;lt;0.001). Finally, in a human tumor xenograft mouse model, low dose gem demonstrated a dose-dependent increase in replication stress markers (Cyclin E, pCHK1 S345) from 0.3-3 mg/kg, which allometrically scales to 1-10 mg/m2 in humans. These data supported a dose escalation Phase 1b/2 clinical study of low dose gem with ACR-368 to evaluate the efficacy and safety of the combination in ACR-368 OncoSignature negative patients (NCT05548296). This shows the potential of AP3 for unbiased elucidation of actionable drug resistance mechanisms and rapid clinical implementation in our trials, which have recently confirmed clinical activity. Citation Format: Helén Nilsson, Lei Shi, Magnus E. Jakobsson, Joelle Baddour-Sousounis, Shahrzad Rafiei, Uthira Muralitharan, Zachary Best, Valentina Siino, Francisco J. Santana, Ignacio Arribas Diez, Kailash Singh, Portia Lombardo, William Dahlberg, Subodh Kumar, Ahmed Youssef, Reina Improgo, Corey Xu, Joon Jung, Jung-Min Lee, Ayesha Murshid, Michail Shipitsin, Jesper V. Olsen, Kristina Masson, David A. Proia, Caroline Wigerup, Peter Blume-Jensen. Acrivon predictive precision proteomics (AP3) uncovers mechanism of resistance to ACR-368, a clinical-stage CHK1/2 inhibitor, and identifies rational combination treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4749.