Low-dose Drug Research Articles

Metronomic chemotherapy: bridging theory to clinical application in canine and feline oncology.

Veterinary oncology has experienced significant evolution over the last few decades, with chemotherapy being currently applied to several neoplasms with therapeutic success. Traditionally, chemotherapy protocols are based on classic cytostatic drugs under the concept of maximum tolerated dose (MTD), which has been associated with a greater risk of toxicity and resistance. Thus, new therapeutic alternatives have emerged, such as metronomic chemotherapy (MC), introducing a new paradigm in cancer treatment. MC consists of administering low doses of chemotherapy drugs continuously over a long period of time, modulating the tumour microenvironment (TME) due to the combination of cytotoxic, antiangiogenic and immunomodulatory effects. This multi-targeted therapy has been described as a treatment option in several canine and feline cancers since 2007, with positive results already published in the literature, particularly in mammary carcinomas and soft tissue sarcomas in dogs. The aim of this review article is to describe the current knowledge about the use of MC in small animal oncology, with emphasis on its mechanisms of action, the most commonly used drugs and clinical outcome.

Better together: nanoscale co-delivery systems of therapeutic agents for high-performance cancer therapy.

Combination therapies can enhance the sensitivity of cancer to drugs, lower drug doses, and reduce side effects in cancer treatment. However, differences in the physicochemical properties and pharmacokinetics of different therapeutic agents limit their application. To avoid the above dilemma and achieve accurate control of the synergetic ratio, a nanoscale co-delivery system (NCDS) has emerged as a prospective tool for combined therapy in cancer treatment, which is increasingly being used to co-load different therapeutic agents. In this study, we have summarized the mechanisms of therapeutic agents in combination for cancer therapy, nanoscale carriers for co-delivery, drug-loading strategies, and controlled/targeted co-delivery systems, aiming to give a general picture of these powerful approaches for future NCDS research studies.

Site-Directed Electrochemical Grafting for Amplified Detection of Antibody Pharmaceuticals.

Antibody pharmaceuticals have become the most popular immunotherapeutic drugs and are often administered with low serum drug dosages. Hence, the development of a highly sensitive method for the quantitative assay of antibody levels is of great importance to individualized therapy. On the basis of the dual signal amplification by the glycan-initiated site-directed electrochemical grafting of polymer chains (glyGPC), we report herein a novel strategy for the amplified electrochemical detection of antibody pharmaceuticals. The target of interest was affinity captured by a DNA aptamer ligand, and then the glycans of antibody pharmaceuticals were decorated with the alkyl halide initiators (AHIs) via boronate cross-linking, followed by the electrochemical grafting of the ferrocenyl polymer chains from the glycans of antibody pharmaceuticals through the electrochemically controlled atom transfer radical polymerization (eATRP). As the glycans can be decorated with multiple AHIs and the grafted polymer chains are composed of tens to hundreds of electroactive tags, the glyGPC-based strategy permits the dually amplified electrochemical detection of antibody pharmaceuticals. In the presence of trastuzumab (Herceptin) as the target, the glyGPC-based strategy achieved a detection limit of 71.5 pg/mL. Moreover, the developed method is highly selective, and the results of the quantitative assay of trastuzumab levels in human serum are satisfactory. Owing to its uncomplicated operation and cost-effectiveness, the glyGPC-based strategy shows great promise in the amplified electrochemical detection of antibody pharmaceuticals.

Chitosan-copper microparticles as doxorubicin microcarriers for bone tumor therapy

Doxorubicin (DOX) is a chemotherapeutic drug used in osteosarcoma treatments, usually administrated in very high dosages. This study proposes novel DOX microcarriers based on chitosan (CHT) physically crosslinked with copper(II) ions that will act synergically to inhibit tumor growth at lower drug dosage without affecting the healthy cells. Spherical CHT-Cu microparticles with a smooth surface and an average size of 30.1 ± 9.1 µm were obtained by emulsion. The release of Cu2+ ions from the CHT-Cu microparticles showed that 99.4 % of added cupric ions were released in 72 h of incubation in a complete cell culture medium (CCM). DOX entrapment in microparticles was conducted in a phosphate buffer solution (pH 6), utilizing the pH sensitivity of the polymer. The successful drug-loading process was confirmed by DOX emitting red fluorescence from drug-loaded microcarriers (DOX@CHT-Cu). The drug release in CCM showed an initial burst release, followed by sustained release. Biological assays indicated mild toxicity of CHT-Cu microparticles on the MG-63 osteosarcoma cell line, without affecting the viability of human mesenchymal stem cells (hMSCs). The DOX@CHT-Cu microparticles at concentration of 0.5 mg mL‒1 showed selective toxicity toward MG-63 cells.

Hyperthermic intraperitoneal chemotherapy in colorectal cancer.

This study evaluated the efficacy of hyperthermic intraperitoneal chemotherapy (HIPEC) in colorectal cancer with peritoneal metastases (pmCRC) in a large international data set of patients. Patients with pmCRC from 39 centres who underwent cytoreductive surgery with HIPEC between 1991 and 2018 were selected and compared for the HIPEC protocols received-oxaliplatin-HIPEC versus mitomycin-HIPEC. Following analysis of crude data, propensity-score matching (PSM) and Cox-proportional hazard modelling were performed. Outcomes of interest were overall survival (OS), recurrence-free survival (RFS) and the HIPEC dose-response effects (high versus low dose, dose intensification and double drug protocols) on OS, RFS and 90-day morbidity. Furthermore, the impact of the treatment time period was assessed. Of 2760 patients, 2093 patients were included. Median OS was 43 months (95% c.i. 41 to 46 months) with a median RFS of 12 months (95% c.i. 12 to 13 months). The oxaliplatin-HIPEC group had an OS of 47 months (95% c.i. 42 to 53 months) versus 39 months (95% c.i. 36 to 43 months) in the mitomycin-HIPEC group (P = 0.002), aHR 0.77, 95% c.i. 0.67 to 0.90, P < 0.001. The OS benefit persisted after PSM of the oxaliplatin-HIPEC group and mitomycin-HIPEC group (48 months (95% c.i. 42 to 59 months) versus 40 months (95% c.i. 37 to 44 months)), P < 0.001, aHR 0.78 (95% c.i. 0.65 to 0.94), P = 0.009. Similarly, matched RFS was significantly higher for oxaliplatin-HIPEC versus others (13 months (95% c.i. 12 to 15 months) versus 11 months (95% c.i. 10 to 12 months, P = 0.02)). High-dose mitomycin-HIPEC protocols had similar OS compared to oxaliplatin-HIPEC. HIPEC dose intensification within each protocol resulted in improved survival. Oxaliplatin + irinotecan-HIPEC resulted in the most improved OS (61 months (95% c.i. 51 to 101 months)). Ninety-day mortality in both crude and PSM analysis was worse for mitomycin-HIPEC. There was no change in treatment effect depending on the analysed time period. Oxaliplatin-based HIPEC provided better outcomes compared to mitomycin-based HIPEC. High-dose mitomycin-HIPEC was similar to oxaliplatin-HIPEC. The 90-day mortality difference favours the oxaliplatin-HIPEC group. A trend for dose-response between low- and high-dose HIPEC was reported.

Abstract PO5-16-12: EFFICACY AND TOLERABILITY OF METRONOMIC CHEMOTHERAPY (mChT) WITH CYCLOPHOSPHAMIDE, METHOTREXATE AND CAPECITABINE (CMX) IN PATIENTS WITH HEAVILY PRETREATED ADVANCED BREAST CANCER. RESULTS FROM A MULTICENTER RETROSPECTIVE STUDY

Abstract BACKGROUND mChT consists on the administration of repetitive, low doses of chemotherapy drugs and represents an attractive and active therapeutic strategy in cancer patients. Beyond the traditional cytotoxic effect of each drug on tumor cells, mChT seems to play a role in the modulation of angiogenesis and immune-regulation. mChT has demonstrated promising clinical activity and low toxicity in patients with advanced breast cancer (ABC). The aim of this study is to describe the safety and efficacy of CMX in a retrospective cohort of heavily pretreated HER2-negative ABC patients. METHODS This is a multicenter, retrospective study that included patients with HER2-negative ABC who received treatment with CMX (capecitabine 500 mg thrice daily, methotrexate 2.5 mg twice a week, and cyclophosphamide 50 mg daily). Demographic data, tumor characteristics, previous therapies, efficacy, and toxicity of the CMX treatment were collected. Statistical analyses were performed with Stata v.14. For standard summary statistics, mean and range for continuous data and relative and absolute frequencies for categorical data were used while for survival analysis Kaplan Meier approach was employed. RESULTS A total of 25 patients from 4 centers in Spain treated between October 2016 and February 2023 were included in this analysis. Median age was 63 years (range: 37-87), 68% had visceral disease, and 48% had triple-negative tumors. All patients previously received a median of 5 prior lines of systemic therapy in the metastatic setting and 80% of patients had been treated with capecitabine, most of them in the metastatic scenario with a median treatment duration of 6.2 months. Dose reductions were necessary in 5 patients and 1 patient discontinued treatment due to toxicity. No grade 3-4 hand-foot syndrome or diarrhea were reported. Objective response rate was 20.8% and disease control rate was 54.2%. Median progression-free survival was 6.1 months (95% confidence interval [CI] 95%; 4.3 - 12.4) and median overall survival was 12.3 months (95% CI; 6.8 - 24.7). Neither the number of previous lines of treatment nor the prior use of capecitabine showed a negative impact on the efficacy of CMX. CONCLUSIONS CMX is an effective and well-tolerated scheme of mChT and may represent an adequate treatment option for patients with heavily pretreated HER2-negative ABC, including those patients that previously received capecitabine as single agent. These encouraging data warrant further investigation. Citation Format: Cristina Saavedra, María Gion, Alfonso Cortés, Patricia Cortez, Laia Garrigós, José Manuel Pérez-García, Gabriele Antonarelli, Javier Cortés. EFFICACY AND TOLERABILITY OF METRONOMIC CHEMOTHERAPY (mChT) WITH CYCLOPHOSPHAMIDE, METHOTREXATE AND CAPECITABINE (CMX) IN PATIENTS WITH HEAVILY PRETREATED ADVANCED BREAST CANCER. RESULTS FROM A MULTICENTER RETROSPECTIVE STUDY [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-16-12.

Apoptotic effect of 5-fluorouracil-doxorubicin combination on colorectal cancer cell monolayers and spheroids.

Drug combination studies help to improve new treatment approaches for colon cancer. Tumor spheroids (3D) are better models than traditional 2-dimensional cultures (2D) to evaluate cellular responses to chemotherapy drugs. The cultivation of cancer cells in 2D and 3D cultures affects the apoptotic process, which is a major factor influencing the response of cancer cells to chemotherapeutic drugs. In this study, the antiproliferative effects of 5-fluorouracil (5-FU) and doxorubicin (DOX) were investigated separately and in combination using 2D and 3D cell culture models on two different colon cancer cell lines, HT-29 (apoptosis-resistant cells) and Caco-2 2 (apoptosis-susceptible cells). The effect of the drugs on the proliferation of both colon cancer cells was determined by performing an MTT assay in 2D culture. The apoptotic effect of 5-FU and DOX, both as single agents and in combination, was assessed in 2D and 3D cultures through quantitative real-time polymerase chain reaction analysis. The expression of apoptotic genes, such as caspases, p53, Bax, and Bcl-2, was quantified. It was found that the mRNA expression of proapoptotic genes was significantly upregulated, whereas the mRNA expression of the antiapoptotic Bcl-2 gene was significantly downregulated in both colon cancer models treated with 5-FU, DOX, and 5-FU + DOX. The results indicated that the 5-FU + DOX combination therapy induces apoptosis and renders 5-FU and DOX more effective at lower concentrations compared to their alone use. This study reveals promising results in reducing the potential side effects of treatment by enabling the use of lower drug doses.

Abstract RF01-06: Efficacy and safety of toripalimab plus metronomic chemotherapy in HER2 negative metastatic breast cancer: a multicenter phase II trial based on a Bayesian adaptive randomized design

Abstract Background: Combining Immune checkpoint blockade (ICB) with chemotherapy may significantly improve efficacy in patients with breast cancer. Metronomic chemotherapy is based on more frequent and low-dose drug administrations compared with conventional chemotherapy. Some clinical studies with small samples have tried the combination of metronomic chemotherapy and ICB in patients with advanced tumors. However, whether metronomic chemotherapy is more suitable for ICB than conventional chemotherapy is still unclear. Thus, we performed the first clinical trial, to our knowledge, of metronomic chemotherapy combined with PD-1 blockade comparing with the efficacy of combined conventional chemotherapy and ICB. Methods: This study is a multicenter randomized phase 2 trial using a multi-arm design with Bayesian adaptive randomization and efficacy monitoring. Eligible patients have advanced HER2 negative breast cancer, with no more than one prior line of standard chemotherapy. Patients were randomized to 5 groups: ① metronomic vinorelbine (NVB, 40 mg/day, TIW) monotherapy (the control cohort); ② NVB + Toripalimab (anti-PD1 antibody, 240 mg Q3W); ③Bevacizumab (5 mg/kg Q3W) + NVB+ Toripalimab (the BEV cohort); ④ Cisplatin (50mg/m Q3W) + NVB + Toripalimab (the DDP cohort), ⑤Cyclophosphamide (50mg/day, QD) + Capecitabine (500 mg, TID) + NVB+ Toripalimab (the VEX cohort). The primary endpoint is disease control rate (DCR), and secondary endpoints are objective response rate (ORR), progression free survival (PFS), and overall survival (OS). The safety profile has also been assessed. Mass cytometry time-of-flight (CyTOF) analyses of paired blood samples were performed to demonstrate dynamic changes in systemic immune profile. Results: A total of 103 patients were randomized. Characteristics were as expected for advanced breast cancer and balanced between cohorts. Adverse events of any grade occurred in 64 patients, with 5.2% grade &amp;gt;3. The rate of nausea was significantly higher in the cisplatin cohort than in the others (P&amp;lt; 0.001). Toripalimab was not associated with any previously unreported toxicity. Among the five treatment cohorts, the VEX cohort and the cisplatin cohort had the highest DCR, 69.7% (95% CI 51.7–85.9%) and 73.7% (95% CI 56.1–88.7%), respectively. Followed by the bevacizumab cohort, DCR is 55.7% (95% CI 37.4%–73.6%). Most objective responses were observed in the VEX cohort (ORR: 18.5%; 95% CI 5.6–34.1%), followed by cisplatin (ORR 14.5%; 95% CI 3.3–29.0%). It is worth noting that the PFS of patients in the VEX cohort was the longest, reaching 6.6 months (95% CI 4.0-5.9), followed by 4.0 months (95% CI 2.4-10.4) in patients of the bevacizumab cohort. The PFS of patients receiving the cisplatin regimen was relatively short, only 3.5 months (95% CI 2.2-5.3). Similarly, patients in the cisplatin cohort had shorter OS than those in the VEX and bevacizumab cohorts. In the TNBC subgroup, again, patients in the VEX cohort had the highest DCR (74.1%, 95%CI 47.9%-95.4%) and longest PFS (9.8 months, 95%CI 3.8-21.9). We obtained over 63 million cells in total and clustered CD45+ immune cells into 32 clusters. The systemic immune profile of patients changed dramatically over 2 cycles of PD-1 blockade. However, only the change of cluster 30 differed between responders and non-responders. This is a group of intermediate monocytes with a high expression of CD38, which decreased in responders but significantly increased in non-responders. CD38-NAD+ axis regulates the PD1+ exhausted T cell function. Meanwhile, the overall expression of CD38 in monocytes was significantly increased by DDP and BEV treatment compared with baseline, but not in the VEX groups. DDP significantly increased the expression level of CD38 on NK cells, while BEV or VEX treatment did not affect it. Conclusions: These data suggest promising clinical efficacy and evidence of cooperativity between metronomic VEX chemotherapy and PD-1 blockade. Citation Format: Hongnan Mo, Xiaoying Sun, Jingtong Zhai, Jiashu Han, Hewei Ge, Yuhan Wei, Xiuwen Guan, Haili Qian, Fei Ma. Efficacy and safety of toripalimab plus metronomic chemotherapy in HER2 negative metastatic breast cancer: a multicenter phase II trial based on a Bayesian adaptive randomized design [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr RF01-06.

Oro-ruminal sampling device and technique for rapid collection of rumen content and improved recovery of solid fractions for microbiome analysis.

Rumen fistulation is a widely used procedure that allows for collection of ruminal contents. However, fistulation is an invasive and costly procedure that generally limits the number of animals that can be recruited for experiments, thus encouraging the use of alternative techniques such as the intra-esophageal tube technique. One of the challenges of this technique is the limited ability to collect solid fractions from the rumen content pool which may impact the microbial community structure in the sample, particularly affecting the recovery and characterization of solid adherent-bacteria. We developed an intra-esophageal tube rumen sampling technique and device referred to as ‘Rumen Sampler MG’ with the aim of increasing the recovery of solid fractions from rumen content compared with other oro-ruminal sampling methods. The ‘Rumen Sampler MG’ device consists of a manual pump fitted with a barometer and an intra-esophageal flexible PVC tube with beveled terminal edge allowing for minimal clogging of the sampling tubing and a rapid flux of contents being sampled. Nine lactating Holstein-Friesian dairy cows (554.6 ± 25.2 kg BW; 8.3 ± 3.3 DIM) were recruited to evaluate the proposed method. During the procedure, animals were safely restrained in a chute and administered with a low dosage of a neuroleptic drug to reduce animal stress during sampling. An endoscopic camera was inserted into the reticulo-rumen through the esophagus to identify the sampling location and determine the length of the sampling tube necessary to reach the desired location. Following, the intra-esophageal sampling tube connected to a manual pump was inserted for collection of rumen contents. Samples collected did not present visual evidence of saliva contamination (e.g., high viscosity) and their pH ranged within expected values (6.33 - 7.04) for samples collected from the reticulo-rumen. Each sample contained 35–40% wet solids volume. Individual dry matter intake and milk production of cows continued to increase after sampling as expected for cows in the early postpartum period, suggesting that the sampling procedure did not affect cow performance. Results from microbiome analysis of rumen content samples suggest that the relative abundances of the main bacterial phyla are consistent with those from samples collected from dairy cows via rumen fistula in previous studies. The device and technique proposed allow for adequate samples of ruminal liquid and solid contents to be collected for microbiome analysis without disruption of animal performance.

SINGLE-PILL COMBINATION OF THIRD-DOSE TRIPLE ANTIHYPERTENSIVE THERAPY VERSUS STANDARD-DOSE MONOTHERAPY IN PATIENTS WITH MILD TO MODERATE HYPERTENSION

Objective: The study compared the single-pill combination of third-dose triple antihypertensive therapy (amlodipine 1.67 mg, losartan potassium 16.67 mg, chlorthalidone 4.17 mg) with standard-dose monotherapy (amlodipine 5mg) in reducing systolic blood pressure (SBP) among patients with mild to moderate hypertension. Design and method: This was a multicenter, randomized, double-blind, active-controlled, parallel-group phase III noninferiority trial. Eligible participants aged &gt;=19 years with SBP &gt;=140 to &lt;180 mmHg and diastolic blood pressure (DBP) &lt;110 mmHg after 4 weeks placebo run-in period were randomized to either 8 weeks of combination therapy (ALC) or monotherapy (A5). The primary efficacy endpoint, noninferiority in SBP reduction, was assessed using the upper limit of the one-sided 97.5% confidence interval (97.5%CI) for the difference in SBP reduction between treatments at week 8, with a noninferiority margin of 3 mmHg. Results: The efficacy endpoint analysis included 167 and 166 in the ALC and A5 groups. After 8 weeks, the ALC and A5 groups showed SBP reductions of -18.3±11.9 and -19.4±12.5, respectively, and DBP reductions of -8.5±7.3 and -9.8±7.0 mmHg, respectively (p&gt;0.025 for both). The unadjusted least-square mean (LSM) difference in SBP reduction was 1.15 mmHg, with a 97.5%CI upper limit of 3.51 mmHg. More female patients were allocated to the A5 than the ALC groups (47.6% vs. 34.1%, p=0.012). Both treatments exhibited greater SBP reduction in women than men (-21.4 vs. -16.8 mmHg, p=0.009 in the ALC group; -21.9 vs -17.1 mmHg, p&lt;0.001 in the A5 group). The sex-adjusted LSM difference in SBP reduction was 0.46 mmHg, with a 97.5%CI upper limit of 2.79 mmHg. The response rates (achieving SBP &lt;140 mmHg and DBP &lt;90 mmHg and/or reduction of SBP &gt;=20 mmHg and/or DBP &gt;=10 mmHg from baseline) were 73.1% for ALC and 75.3% for A5 groups (p=0.633). Adverse drug reactions (ADRs) occurred in 3 patients receiving ALC and 5 patients receiving A5, all being mild. Conclusions: The study demonstrated that the single-pill third-dose triple antihypertensive therapy is comparable to standard-dose monotherapy in reducing SBP over 8 weeks without increasing ADRs, providing further support for the low-dose combination antihypertensive drugs in the initial treatment of hypertension. (NCT05362110)

Ultrasound combined blood‐brain barrier targeting brain delivery of four‐in‐one molecular aggregates for the enhancement of anesthetic efficacy and toxicity reduction via propofol‐etomidate synergistically inhibition GABA receptor

AbstractTo enhance the anesthetic efficacy and reduce toxic side effects, a strategy is proposed involving the utilization of general anesthetics of Propofol (Pro) and Etomidate (Eto) to synergistic inhibition GABA receptors simultaneously. Four‐in‐one molecular aggregates were prepared to implement this strategy, which comprised of Pro and Eto with the bridging molecule monoglyceride monooleate (GMO) and surfactant F127 through intermolecular forces. The blood‐brain barrier (BBB) targeted lactoferrin (LF) is affixed to their surface, obtaining the final molecular aggregates. By employing lactoferrin enrich aggregates to the BBB, followed by ultrasound combine microbubbles to open the BBB, a remarkable 4.5‐fold enhancement in brain drug delivery was achieved. The molecular aggregates group maintained stable parameters of heart rate, diastolic blood pressure, and systolic blood pressure. A notable increase of more than twice therapeutic index (TI) value was observed, implying their higher anesthesia efficiency and reduced toxicity. Electroencephalogram (EEG) experiments demonstrate a significant elevation in the proportion of δ waves from 28% to 80% for aggregates, accompanied by a nearly fivefold reduction in the proportion of θ waves, meaning a significant improvement in synergistic anesthesia effectiveness (interaction index 0.289) with lower drug dosage. Furthermore, mouse immunofluorescence brain slice experiments suggest Pro and Eto enter the GABA receptor simultaneously, resulting in synergistic inhibition of GABA receptors.

Intracoronary microcatheter indwelling for continuous pumping of low-dose thrombolytic drugs: A new approach to reperfusion in acute myocardial infarction.

Reperfusion therapy of acute myocardial infarction (AMI) refers to physical or chemical recanalization and restoration of blood flow to an occluded coronary artery, and current techniques for reperfusion therapy include intravenous thrombolysis, percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The number of patients receiving emergency CABG in the real world is decreasing due to the disadvantages of CABG and the improvement in PCI procedures. Thrombolytic therapy has some disadvantages such as low recanalization rate, high risk of reocclusion and bleeding, and short time window. On the other hand, intracoronary interventional therapy may meet the requirements of "early, complete and persistent" patency of coronary arteries at different time points. However, in the emergency PCI, although thrombus aspiration via a catheter or balloon dilation is performed, residual thrombus with heavy or low TIMI (thrombolysis in myocardial infarction) myocardial perfusion grading is still observed in some patients, suggesting disordered microcirculation. Currently, the treatment of microcirculatory disturbance in emergency PCI mainly employed injection of tirofiban, adenosine, thrombolytic agent or other drugs into the local area via a microcatheter in a short time, all of which can significantly reduce the thrombus load and improve TIMI perfusion. Herein, we report that a microcatheter was indwelled in the coronary artery for continuous pumping of low-dose thrombolytic drugs as reperfusion therapy in 12 patients with acute and subacute MI.

Serotonin Syndrome Following Low-Dose Sertraline: A Case Report

IntroductionSerotonin syndrome is a potentially life-threatening condition that is precipitated by the use of serotonergic medications, Selective Serotonin Reuptake Inhibitors (SSRIs) and Monoamine Oxidase Inhibitors (MAOIs). It usually occurs when high doses of serotonergic drugs are prescribed. It is a medical emergency that requires prompt recognition, cessation of offending drugs and supportive therapy.ObjectivesWe present a case of serotonin syndrome that occurred in a patient who was prescribed a low dose of sertraline, and aim to highlight the importance of early detection of this severe condition.MethodsDetails of the case were described. Information was gathered based on medical records.Results Patient M was a 29-year-old Malay male with a history of major depressive disorder, who was previously trialed on fluvoxamine 100mg every night but subsequently switched to and maintained on sertraline 75mg every night in 2020. He then defaulted follow up appointments. In 2023, he presented to the emergency services for a suicide attempt and was diagnosed with major depressive disorder with psychotic features. He was restarted on sertraline 50mg every night and risperidone 0.5mg every night was newly started. Two days later, sertraline was increased to 100mg every night. Two days following this increase, he was noted to have altered mental state, fever of 39.3-degree celcius, tachycardia of 120 beats per minute, ocular clonus and generalized hyperreflexia. Sertraline and risperidone were immediately stopped. Blood tests including creatine kinase, lumbar puncture and magnetic resonance imaging (MRI) of the brain did not show any abnormalities. After stopping of the medications, the patient’s symptoms resolved within 24 hours. Based on clinical symptoms and a normal creatine kinase level, neuroleptic malignant syndrome (NMS) was ruled out. Subsequently, he was restarted on risperidone 0.5mg and mirtazapine 7.5mg every night. He developed symptoms of serotonin syndrome with a low dose of sertraline. Symptoms resolved after the discontinuation of the SSRI.Conclusions In this case, differential diagnoses of serotonin syndrome were also considered, such as NMS, encephalitis, meningitis and thyroid storm. NMS was less likely due to the rapid onset of onset and resolution of symptoms. Encephalitis and meningitis were unlikely in view of normal MRI brain and lumbar puncture findings.There have been case reports of serotonin syndrome developing with lower doses of an SSRI in the pediatric population. There is, however, a lack of literature describing serotonin syndrome with low doses of SSRI in the adult population. To avoid a missed diagnosis, clinicians should monitor closely for SSRI toxicity, including serotonin syndrome, even when low doses of serotonergic drugs are used.Disclosure of InterestNone Declared

Inflammatory Response Modulation by Low-Dose Anti-inflammatory Drugs Treatment in an In Vitro Osteoarthritis Cellular Model.

Low-dose-medicine is based on the administration of low doses of biological regulators to restore the immunologic balance altered in the disease. Cytokines are pivotal regulators of cellular and tissue functions and impaired crosstalk, due to an imbalance between specific cytokines, it is fundamental in acute inflammation and diseases correlated to low-grade chronic inflammation. Osteoarthritis is the most prevalent arthritic disease and a leading cause of disability. In the treatment of muscle- skeletal pathologies, the therapeutic integration of conventional medicine with homotoxicology, or low-dose-medicine appears to be beneficial. This study aims to get more insights into the role of inflammatory cytokines and chemokines during the development of osteoarthritis and to evaluate a possible blocking strategy using anti-inflammatory molecules, we resort to an in vitro experimental model using an established human chondrosarcoma cell line that underwent to a well known pro-inflammatory stimulus as bacterial lipopolysaccharide. We tested the production of inflammatory-related cytokines and chemokines, and the efficacy of low-dose (LD) administration of anti-inflammatory compounds, namely IL-10 and anti-IL-1, to block inflammatory cellular pathways. Following an inflammatory insult, chondrocytes upregulated the expression of several pro-inflammatory cyto-/chemokines and this induction could be counteracted by LD IL-10 and anti-IL-1. We reported that these effects could be ascribed to an interfering effect of LD drugs with the NF-κB signaling. Our results provided a good indication that LD drugs can be effective in inhibiting the inflammatory response in chondrocytes opening the way to new therapies for the treatment of diseases such as osteoarthritis.

Abstract 7625: The liquid biomarker thymidine kinase activity reflecting proliferation rate can provide guidance in drug development and address Project Optimus

Abstract Thymidine Kinase (TK) plays a basic role in DNA synthesis and cell proliferation. The enzyme is highly cell cycle dependent and correlates with cell growth state. Numerous studies have consistently shown elevated TK activity (TKa) in the blood of patients with solid tumors and active disease. DiviTum® TKa, a clinically and analytically validated FDA cleared assay, measures and quantifies TKa in serum or plasma in humans and animals. TKa as a biomarker offers valuable information at all stages of drug development, from drug efficacy and dose response studies in cell culture and xenograft models, to patient selection and treatment monitoring in clinical trials. The launch of FDA Project Optimus highlights the need for new biomarkers to assist in drug development to identify optimal dose. Using TKa to measure the impact on cell proliferation as a drug evaluation endpoint can confirm mechanism of action efficacy and a minimally effective dose of a new compound rather than a maximally tolerated dose. TKa can be used as a pharmacodynamic tool to improve study endpoints. TKa data in cultured cells and mouse xenografts demonstrates that a complete shutdown of tumor cell proliferation can be observed well before and at much lower drug-doses than when cell death or toxicity is used as the dose determination endpoint. Increased dosing of CDK4/6 inhibitors demonstrates immediate impact on TKa levels in cell lines and provides signals of drug effect at doses where cell viability is unaffected. After initiation of samuraciclib treatment, a CDK7 inhibitor, a significant reduction in TKa levels in blood from metastatic breast cancer (MBC) patients was observed, indicating inhibition of cell cycle progression. For patients on samuraciclib therapy and with stable disease before progression, TKa levels were significantly lower than pre-treatment (p=0.0038). Post-progression TKa levels increased to significantly higher levels than during therapy including the last sample measured before progression (p=0.014). Baseline blood TKa levels are predictive for progression free survival (PFS) allowing for the early stratification of patients with long vs short PFS. In patients with MBC, TKa levels during the first treatment cycle are strongly predictive for PFS. Suppressed TKa levels after 2 and 4 weeks of CDK4/6 inhibitor therapy predict longer PFS than high TKa levels at the same time points (HR 5.65; p&amp;lt; 0.0001). MBC patients monitored &amp;gt;3 months and showing low TKa levels have very low likelihood of progression within 30- to 60 days, &amp;lt;2% and &amp;lt;6%, respectively. TKa is a translational liquid biomarker that bridges results between preclinical and clinical studies, providing fundamental information for drug development decision making. Citation Format: Mattias Bergqvist, Hanna Ritzén, Amy Williams. The liquid biomarker thymidine kinase activity reflecting proliferation rate can provide guidance in drug development and address Project Optimus [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 7625.

Abstract 1850: From proteomic analysis to early investigations of combining inhibitors targeting PCNA and histone deacetylase

Abstract Proteomic changes were investigated in a neuroblastoma cell line, SK-N-AS, treated with a small molecule inhibitor, AOH1996, designed to specifically bind proliferating cell nuclear antigen (PCNA) in cancer. PCNA is crucial to DNA replication, DNA repair, transcription, cell cycle control, and chromatin organization through interactions with different proteins. Pathway analysis of differential protein expressions between treated and untreated cells revealed less G2/M DNA damage checkpoint regulation and decreased assembly of RNA polymerase complex. Phosphoproteomic analysis by PTM Signature Enrichment Analysis (PTM-SEA) identified signatures of kinase activities, signaling pathways, and perturbations. Specifically, the histone deacetylase inhibitors belinostat and vorinostat were identified as enriched perturbation signatures. Both inhibitors were tested in combination with AOH1996 in SK-N-AS as well as cell lines derived from breast, lung, ovarian, and pancreatic cancer, revealing drug synergies at specific dose combinations. Western blot analysis showed that belinostat decreased protein expression of PCNA, suggestive of mechanistic synergies with AOH1996+belinostat combination therapies. Our proteomic analysis reveals a therapeutic potential of combining AOH1996 and histone deacetylase inhibitors for treating cancer with possibly lower drug dose and toxicities compared to single drug treatment. Citation Format: Caroline M. Li, Krystine Garcia-Mansfield, Robert G. Lingeman, Long Gu, Robert J. Hickey, Patrick Pirrotte, Linda H. Malkas. From proteomic analysis to early investigations of combining inhibitors targeting PCNA and histone deacetylase [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 1850.

Abstract 6485: Profile guided low dose drug combination strategies and kinase activities with prognostic and therapeutic avenues in pancreatic ductal adenocarcinoma

Abstract Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease, commonly characterized by multiple aberrant signaling. Phosphoproteomics provides a direct read-out of these complex signaling networks and the resultant clinically relevant phenotype, as well as a functional scaffold to identify new targets. In the absence of an oncogenic driver, low dose (LD) kinase inhibitor (KI) combinations against multiple (parallel) activated kinases might provide higher efficacy and reduce toxicity as compared to single drug treatment. Aims: 1) To identify targets and test combinations of multiple KIs at LDs for potential synergism in preclinical models. 2) To chart the phosphoproteome of 42 PDAC tumors to reveal signalling pathways that may be involved in PDAC progression. Methods: By using a two step phosphopeptide enrichment with phosphotyrosine immunoprecipitation and immobilized metal affinity chromatography, followed by label free MS analysis, we analyzed phosphoproteome data of 7 immortalized and 2 primary PDAC cell lines, and of 42 PDAC tumors. We used integrative inferred kinase activity (INKA) scoring of the maxquant output to identify hyperactive kinases. For the cell line panel, five KIs were selected based on targeting coverage of the INKA profiles. LD were set as IC20s for 2,3,4 drug combinations. Cell growth inhibition was assessed by SRB assay. Median-effect analysis was used to assess synergy. Functional testing was performed in immortalized 2D, xenoderived 2D and 3D cultures. Effective low dose 3 drug combinations were further validated using patient-derived xenografts. Results: High INKA scoring of multiple activities per cell line without clear outliers of single kinases underscores the need for combination therapies. Multiple LD combinations showed effective growth inhibition (70 to 92%) and synergism, mostly 3 drug combinations, which required targeting of several RTKs and downstream signaling. Different responses were further observed between epithelial and mesenchymal cell lines. These top performing combinations were further validated in PDAC organoids and in vivo. Clinical utility of these kinase targets was then confirmed in 42 tumor phosphoprofiles, which were characterized in different subtypes with distinct therapeutic options. Phosphoproteome signals and kinases activities with potential prognostic value and mutational associations were further described. Conclusion: Our INKA pipeline, which can rank kinase activities in individual tumors, is optimally suited to specifically prioritize actionable kinases with targeting purposes. Tailored LD combination strategies exhibited promising efficacy in preclinical models and may ultimately improve treatment outcomes. Next Steps: Multicellular patient-derived models will be used to further study and target the TME in PDAC tumors. Citation Format: Andrea Vallés Martí, Giulia Mantini, Cynthia Waasdorp, Richard R. de Goeij- de Haas, Alex A. Henneman, Sander R. Piersma, Thang V. Pham, Jaco C. Knol, Joanne Verheij, Frederike Dijk, Hans Halfwerk, Elisa Giovannetti, Connie R. Jiménez, Maarten F. Bijlsma. Profile guided low dose drug combination strategies and kinase activities with prognostic and therapeutic avenues in pancreatic ductal adenocarcinoma [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 6485.

Synergistic potential of α-Phellandrene combined with conventional antifungal agents and its mechanism against antibiotic resistant Candida albicans

Candida albicans is resistant to various antifungal drugs, this presents a significant problem on a global scale. This study investigates a novel approach on the potential fungicidal effects of α-Phellandrene combinations with fluconazole and amphotericin B against antibiotic resistant C. albicans. The agar well diffusion experiment was used to measure the anti-candida activity of α-Phellandrene which exhibited a zone of inhibition of 24 ± 0.5 mm and 22 ± 0.5 mm against the C. albicans cells (MTCC277 and ATCC90028), respectively. Additionally, the fungicidal minimum inhibitory concentration (MIC) ranged 0.0312–0.0156 mg/ml (w/v) against C. albicans strains. It was determined to have powerful and efficient antifungal action against Candida cells. Further, the synergistic potential was evaluated by employing a time kill assay and a checkerboard technique, respectively, which revealed after 16 h, the colony count of C. albicans cells ATCC90028 (2.56 ± 0.33) and MTCC277 (2.53 ± 0.33) dropped by a log10 when treated with a combination of α-Phellandrene and Fluconazole and α-Phellandrene and amphotericin B exhibited synergy against both C. albicans strains ATCC90028 and MTCC277 (2.42 ± 0.28 and 2.00 ± 0.21) log10 reduction in colony count, respectively, Additionally, 16–624-fold increase in the antifungal efficacy of clinical medicines, with total cell death occurring after 16 h. α-Phellandrene and antifungal drugs were tested in combination with the osmoprotectant test, ergosterol test and FESEM observations to determine their modes of action. In the era of multidrug-resistant diseases antibiotic resistance can be curtailed in its tracks with the help of combination treatments that allow for lower drug doses.

A228 RISANKIZUMAB - DRUG INDUCED LIVER INJURY; A CASE REPORT

Abstract Background Risankizumab is a humanized monoclonal antibody to IL-23. It was initially used in the treatment of plaque psoriasis with recent approval to extend use to treat moderate to severe Crohn’s disease with evidence of endoscopic healing and clinical remission of disease. In the drugs safety manual, it has been reported to have transient liver enzyme elevation that is asymptomatic and not to a degree requiring drug discontinuation. No reported data on steatohepatitis. In this article we describe a 28 year old female, who had no evidence of liver disease in the past who underwent treatment with Risankizumab and within several months developed evidence of steatohepatitis with radiological evidence of significant hepatomegaly. Aims Case report details Drug induced liver injury to Risankizumab. Methods Case Report Results Drug induced liver injury with elevated liver enzyme levels and liver biopsy showing drug related liver changes likely in the setting of Risankizumab use. Conclusions Risankizumab is a newly approved drug in the setting of Crohn's disease, although described in the drug assessment report that it may cause transient hepatitis or eleveted liver enzymes in the setting of lower drug dose for Psoriasis use, the higher drug level used in the setting of Crohn's disease has not been formally evaluated and no previous known case reports of Drug induced Liver Injury to Risankizumab causing severe steatohepatitis Funding Agencies None

Mitigating non-genetic resistance to checkpoint inhibition based on multiple states of immune exhaustion

Despite the revolutionary impact of immune checkpoint inhibition on cancer therapy, the lack of response in a subset of patients, as well as the emergence of resistance, remain significant challenges. Here we explore the theoretical consequences of the existence of multiple states of immune cell exhaustion on response to checkpoint inhibition therapy. In particular, we consider the emerging understanding that T cells can exist in various states: fully functioning cytotoxic cells, reversibly exhausted cells with minimal cytotoxicity, and terminally exhausted cells. We hypothesize that inflammation augmented by drug activity triggers transitions between these phenotypes, which can lead to non-genetic resistance to checkpoint inhibitors. We introduce a conceptual mathematical model, coupled with a standard 2-compartment pharmacometric (PK) model, that incorporates these mechanisms. Simulations of the model reveal that, within this framework, the emergence of resistance to checkpoint inhibitors can be mitigated through altering the dose and the frequency of administration. Our analysis also reveals that standard PK metrics do not correlate with treatment outcome. However, we do find that levels of inflammation that we assume trigger the transition from the reversibly to terminally exhausted states play a critical role in therapeutic outcome. A simulation of a population that has different values of this transition threshold reveals that while the standard high-dose, low-frequency dosing strategy can be an effective therapeutic design for some, it is likely to fail a significant fraction of the population. Conversely, a metronomic-like strategy that distributes a fixed amount of drug over many doses given close together is predicted to be effective across the entire simulated population, even at a relatively low cumulative drug dose. We also demonstrate that these predictions hold if the transitions between different states of immune cell exhaustion are triggered by prolonged antigen exposure, an alternative mechanism that has been implicated in this process. Our theoretical analyses demonstrate the potential of mitigating resistance to checkpoint inhibitors via dose modulation.