Genetic Variants of ABC and SLC Transporter Genes and Chronic Myeloid Leukaemia: Impact on Susceptibility and Prognosis.

Solute carrier (SLC) and ATP-binding cassette (ABC) transporters comprise a variety of proteins expressed on cell membranes responsible for intrusion or extrusion of substrates, respectively, including nutrients, xenobiotics, and chemotherapeutic agents. These transporters mediate the cellular disposition of tyrosine kinase inhibitors (TKIs), and their genetic variants could affect its function, potentially predisposing patients to chronic myeloid leukaemia (CML) and modulating treatment response. We explored the impact of genetic variability (single nucleotide variants-SNVs) of drug transporter genes (ABCB1, ABCG2, SLC22A1, and SLC22A5) on CML susceptibility, drug response, and BCR-ABL1 mutation status. We genotyped 10 SNVs by tetra-primers-AMRS-PCR in 198 CML patients and 404 controls, and assessed their role in CML susceptibility and prognosis. We identified five SNVs associated with CML predisposition, with some variants increasing disease risk, including TT genotype ABCB1 (rs1045642), and others showing a protective effect (GG genotype SLC22A5 rs274558). We also observed different haplotypes and genotypic profiles associated with CML predisposition. Relating to drug response impact, we found that CML patients with the CC genotype (rs2231142 ABCG2) had an increased risk of TKI resistance (six-fold). Additionally, CML patients carrying the CG genotype (rs683369 SLC22A1) presented a 4.54-fold higher risk of BCR-ABL1 mutations. Our results suggest that drug transporters' SNVs might be involved in CML susceptibility and TKI response, and predict the risk of BCR-ABL1 mutations, highlighting the impact that SNVs could have in therapeutic selection.

Flow cytometry and targeted immune transcriptomics identify distinct profiles in patients with chronic myeloid leukemia receiving tyrosine kinase inhibitors with or without interferon-α.

BACKGROUND: Tumor cells have evolved complex strategies to escape immune surveillance, a process which involves NK cells and T lymphocytes, and various immunological factors. Indeed, tumor cells recruit immunosuppressive cells [including regulatory T-cells (Treg), myeloid-derived suppressor cells (MDSC)] and express factors such as PD-L1. Molecularly targeted therapies, such as imatinib, have off-target effects that may influence immune function. Imatinib has been shown to modulate multiple cell types involved in anti-cancer immune surveillance, with potentially detrimental or favorable outcomes. Imatinib and other tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia (CML) have dramatically changed disease course. Our study aimed to characterize the different populations of the immune system in patients with CML affected by their treatment. METHODS: Forty-one patients with CML [33 treated with TKIs and 8 with TKIs plus interferon (IFN)-α] and 20 controls were enrolled in the present study. Peripheral blood populations of the immune system [referred to as the overview of immune system (OVIS) panel, Treg cells and MDSCs] and PD-1 expression were evaluated by flow cytometry. The immunological profile was assessed using the mRNA Pan-Cancer Immune Profiling Panel and a NanoString nCounter FLEX platform. RESULTS: Patients receiving combination therapy (TKIs + IFN-α) had lower numbers of lymphocytes, particularly T cells [838/µL (95% CI 594-1182)] compared with healthy controls [1500/µL (95% CI 1207 - 1865), p = 0.017]. These patients also had a higher percentage of Treg (9.1%) and CD4+PD-1+ cells (1.65%) compared with controls [Treg (6.1%) and CD4+/PD-1+(0.8%); p ≤ 0.05]. Moreover, patients treated with TKIs had more Mo-MDSCs (12.7%) whereas those treated with TKIs + IFN-α had more Gr-MDSC (21.3%) compared to controls [Mo-MDSC (11.4%) and Gr-MDSC (8.48%); p ≤ 0.05]. CD56bright NK cells, a cell subset endowed with immune-regulatory properties, were increased in patients receiving TKIs plus IFN-α compared with those treated with TKIs alone. Interestingly, serum IL-21 was significantly lower in the TKIs plus IFN-α cohort. Within the group of patients treated with TKI monotherapy, we observed that individuals receiving 2nd generation TKIs had lower percentages of CD4+ Treg (3.63%) and Gr-MDSC (4.2%) compared to patients under imatinib treatment (CD4+ Treg 6.18% and Gr-MDSC 8.2%), but higher levels of PD-1-co-expressing CD4+ cells (1.92%). CONCLUSIONS: Our results suggest that TKIs in combination with IFN-α may promote an enhanced immune suppressive state.

Clinical benefit of eculizumab in patients with no transfusion history in the International Paroxysmal Nocturnal Haemoglobinuria Registry.

BACKGROUND: Eculizumab reduces intravascular haemolysis and improves disease symptoms in patients with paroxysmal nocturnal haemoglobinuria (PNH). AIMS: To characterise, in a real-world setting, the effect of eculizumab in patients with haemolytic PNH (lactase dehydrogenase (LDH) ≥ 1.5 upper limit of normal) and no history of red blood cell transfusion, including those with high disease activity (HDA). METHODS: Three populations from the International PNH Registry were studied: (i) non-transfused, untreated; (ii) non-transfused, eculizumab-treated and (iii) transfused, eculizumab-treated (≥1 transfusions in 6 months prior to eculizumab initiation). Using multivariate linear regression, the primary outcome was mean absolute change from baseline to 6 months in LDH (U/L) in non-transfused patients who were treated with eculizumab versus those who remained untreated. Secondary outcomes were mean changes in functional assessment of chronic illness therapy (FACIT)-Fatigue and European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ)-C30 Fatigue scores from baseline to last available assessment. RESULTS: The study population included (i) 144 non-transfused, untreated patients; (ii) 45 non-transfused, eculizumab-treated patients and (iii) 105 transfused, eculizumab-treated patients. Of these, 136/144, 43/45 and 99/105 had HDA respectively. Compared with untreated patients, non-transfused, treated patients had greater absolute reduction in LDH (-1318.8 vs -39.4; P < 0.001) and greater percentage reduction in LDH (-69.9 vs -1.6%; P < 0.001). Clinically meaningful improvements in FACIT-Fatigue (73.7 vs 24.6%, respectively) and in EORTC-QLQ-C30 (84.2 vs 33.3%, respectively) were observed. Non-transfused, treated patients with HDA had significantly reduced LDH levels (P < 0.001) and clinically meaningful improvements in FACIT-Fatigue (P = 0.003) and EORTC-QLQ-C30 (P = 0.020) versus untreated patients. CONCLUSION: Significant LDH reduction and clinically meaningful improvement in fatigue were observed in patients with PNH and HDA treated with eculizumab versus untreated patients, irrespective of transfusion history.

Clinical Outcomes of 217 Patients with Acute Erythroleukemia According to Treatment Type and Line: A Retrospective Multinational Study.

Acute erythroleukemia (AEL) is a rare disease typically associated with a poor prognosis. The median survival ranges between 3-9 months from initial diagnosis. Hypomethylating agents (HMAs) have been shown to prolong survival in patients with myelodysplastic syndromes (MDS) and AML, but there is limited data of their efficacy in AEL. We collected data from 210 AEL patients treated at 28 international sites. Overall survival (OS) and PFS were estimated using the Kaplan-Meier method and the log-rank test was used for subgroup comparisons. Survival between treatment groups was compared using the Cox proportional hazards regression model. Eighty-eight patients were treated with HMAs, 44 front line, and 122 with intensive chemotherapy (ICT). ICT led to a higher overall response rate (complete or partial) compared to first-line HMA (72% vs. 46.2%, respectively; p ≤ 0.001), but similar progression-free survival (8.0 vs. 9.4 months; p = 0.342). Overall survival was similar for ICT vs. HMAs (10.5 vs. 13.7 months; p = 0.564), but patients with high-risk cytogenetics treated with HMA first-line lived longer (7.5 for ICT vs. 13.3 months; p = 0.039). Our results support the therapeutic value of HMA in AEL.

Cell-type-specific transcriptional regulation of PIGM underpins the divergent hematologic phenotype in inherited GPl deficiency.

A rare point mutation in the core promoter -270GC-rich box of PIGM, a housekeeping gene, disrupts binding of the generic transcription factor (TF) Sp1 and causes inherited glycosylphosphatidylinositol (GPI) deficiency (IGD). We show that whereas PIGM messenger RNA levels and surface GPI expression in IGD B cells are low, GPI expression is near normal in IGD erythroid cells. This divergent phenotype results from differential promoter chromatin accessibility and binding of Sp1. Specifically, whereas PIGM transcription in B cells is dependent on Sp1 binding to the -270GC-rich box and is associated with lower promoter accessibility, in erythroid cells, Sp1 activates PIGM transcription by binding upstream of (but not to) the -270GC-rich box. These findings explain intact PIGM transcription in IGD erythroid cells and the lack of clinically significant intravascular hemolysis in patients with IGD. Furthermore, they provide novel insights into tissue-specific transcriptional control of a housekeeping gene by a generic TF.

Validation of the revised international prognostic scoring system (IPSS-R) in patients with lower-risk myelodysplastic syndromes: a report from the prospective European LeukaemiaNet MDS (EUMDS) registry.

Baseline characteristics, disease-management and outcome of 1000 lower-risk myelodysplastic syndrome (MDS) patients within the European LeukaemiaNet MDS (EUMDS) Registry are described in conjunction with the validation of the revised International Prognostic Scoring System (IPSS-R). The EUMDS registry confirmed established prognostic factors, such as age, gender and World Health Organization 2001 classification. Low quality of life (EQ-5D visual analogue scale score) was significantly associated with reduced survival. A high co-morbidity index predicted poor outcome in univariate analyses. The IPSS-R identified a large group of 247 patients with Low (43%) and Very low (23%) risk score within the IPSS intermediate-1 patients. The IPSS-R also identified 32 High or Very high risk patients within the IPSS intermediate-1 patients. IPSS-R was superior to the IPSS for predicting both disease progression and survival. Seventy percent of patients received MDS-specific treatment or supportive care, including red blood cell transfusions (51%), haematopoietic growth factors (58%) and iron chelation therapy (8%), within 2 years of diagnosis; while 30% of the patients only required active monitoring. The IPSS-R proved its utility as a more refined risk stratification tool for the identification of patients with a very good or poor prognosis and in this lower-risk MDS population.

Immune-monitoring of myelodysplastic neoplasms: Recommendations from the i4MDS consortium.

Advancements in comprehending myelodysplastic neoplasms (MDS) have unfolded significantly in recent years, elucidating a myriad of cellular and molecular underpinnings integral to disease progression. While molecular inclusions into prognostic models have substantively advanced risk stratification, recent revelations have emphasized the pivotal role of immune dysregulation within the bone marrow milieu during MDS evolution. Nonetheless, immunotherapy for MDS has not experienced breakthroughs seen in other malignancies, partly attributable to the absence of an immune classification that could stratify patients toward optimally targeted immunotherapeutic approaches. A pivotal obstacle to establishing "immune classes" among MDS patients is the absence of validated accepted immune panels suitable for routine application in clinical laboratories. In response, we formed International Integrative Innovative Immunology for MDS (i4MDS), a consortium of multidisciplinary experts, and created the following recommendations for standardized methodologies to monitor immune responses in MDS. A central goal of i4MDS is the development of an immune score that could be incorporated into current clinical risk stratification models. This position paper first consolidates current knowledge on MDS immunology. Subsequently, in collaboration with clinical and laboratory specialists, we introduce flow cytometry panels and cytokine assays, meticulously devised for clinical laboratories, aiming to monitor the immune status of MDS patients, evaluating both immune fitness and identifying potential immune "risk factors." By amalgamating this immunological characterization data and molecular data, we aim to enhance patient stratification, identify predictive markers for treatment responsiveness, and accelerate the development of systems immunology tools and innovative immunotherapies.

Hypomorphic promoter mutation in PIGM causes inherited glycosylphosphatidylinositol deficiency.

Attachment to the plasma membrane by linkage to a glycosylphosphatidylinositol (GPI) anchor is a mode of protein expression highly conserved from protozoa to mammals. As a clinical entity, deficiency of GPI has been recognized as paroxysmal nocturnal hemoglobinuria, an acquired clonal disorder associated with somatic mutations of the X-linked PIGA gene in hematopoietic cells. We have identified a novel disease characterized by a propensity to venous thrombosis and seizures in which deficiency of GPI is inherited in an autosomal recessive manner. In two unrelated kindreds, a point mutation (c --> g) at position -270 from the start codon of PIGM, a mannosyltransferase-encoding gene, disrupts binding of the transcription factor Sp1 to its cognate promoter motif. This mutation substantially reduces transcription of PIGM and blocks mannosylation of GPI, leading to partial but severe deficiency of GPI. These findings indicate that biosynthesis of GPI is essential to maintain homeostasis of blood coagulation and neurological function.

Combination of Elacridar with Imatinib Modulates Resistance Associated with Drug Efflux Transporters in Chronic Myeloid Leukemia.

Multidrug resistance (MDR) development has emerged as a complication that compromises the success of several chemotherapeutic agents. In chronic myeloid leukemia (CML), imatinib resistance has been associated with changes in BCR-ABL1 and intracellular drug concentration, controlled by SLC and ABC transporters. We evaluate the therapeutic potential of a P-glycoprotein and BCRP inhibitor, elacridar, in sensitive (K562 and LAMA-84) and imatinib-resistant (K562-RC and K562-RD) CML cell lines as monotherapy and combined with imatinib. Cell viability was analyzed by resazurin assay. Drug transporter activity, cell death, cell proliferation rate, and cell cycle distribution were analyzed by flow cytometry. Both resistant models presented an increased activity of BCRP and P-gP compared to K562 cells. Elacridar as monotherapy did not reach IC50 in any CML models but activated apoptosis without cytostatic effect. Nevertheless, the association of elacridar (250 nM) with imatinib overcomes resistance, re-sensitizing K562-RC and K562-RD cells with five and ten times lower imatinib concentrations, respectively. Drug combination induced apoptosis with increased cleaved-caspases-3, cleaved-PARP and DNA damage, reduced cell proliferation rate, and arrested CML cells in the S phase. These data suggest that elacridar combined with imatinib might represent a new therapeutic option for overcoming TKI resistance involving efflux transporters.

Resistance to Tyrosine Kinase Inhibitors in Chronic Myeloid Leukemia-From Molecular Mechanisms to Clinical Relevance.

Resistance to targeted therapies is a complex and multifactorial process that culminates in the selection of a cancer clone with the ability to evade treatment. Chronic myeloid leukemia (CML) was the first malignancy recognized to be associated with a genetic alteration, the t(9;22)(q34;q11). This translocation originates the BCR-ABL1 fusion gene, encoding the cytoplasmic chimeric BCR-ABL1 protein that displays an abnormally high tyrosine kinase activity. Although the vast majority of patients with CML respond to Imatinib, a tyrosine kinase inhibitor (TKI), resistance might occur either de novo or during treatment. In CML, the TKI resistance mechanisms are usually subdivided into BCR-ABL1-dependent and independent mechanisms. Furthermore, patients' compliance/adherence to therapy is critical to CML management. Techniques with enhanced sensitivity like NGS and dPCR, the use of artificial intelligence (AI) techniques, and the development of mathematical modeling and computational prediction methods could reveal the underlying mechanisms of drug resistance and facilitate the design of more effective treatment strategies for improving drug efficacy in CML patients. Here we review the molecular mechanisms and other factors involved in resistance to TKIs in CML and the new methodologies to access these mechanisms, and the therapeutic approaches to circumvent TKI resistance.

A systematic literature review of disease burden and clinical efficacy for patients with relapsed or refractory acute myeloid leukemia.

Acute myeloid leukemia (AML) is a rapidly progressive hematological malignancy that is difficult to cure. The prognosis is poor and treatment options are limited in case of relapse. A comprehensive assessment of current disease burden and the clinical efficacy of non-intensive therapies in this population are lacking. We conducted two systematic literature reviews (SLRs). The first SLR (disease burden) included observational studies reporting the incidence and economic and humanistic burden of relapsed/refractory (RR) AML. The second SLR (clinical efficacy) included clinical trials (phase II or later) reporting remission rates (complete remission [CR] or CR with incomplete hematologic recovery [CRi]) and median overall survival (mOS) in patients with RR AML or patients with de novo AML who are ineligible for intensive chemotherapy. For both SLRs, MEDLINE®/Embase® were searched from January 1, 2008 to January 31, 2020. Clinical trial registries were also searched for the clinical efficacy SLR. After screening, two independent reviewers determined the eligibility for inclusion in the SLRs based on full-text articles. The disease burden SLR identified 130 observational studies. The median cumulative incidence of relapse was 29.4% after stem cell transplant and 46.8% after induction chemotherapy. Total per-patient-per-month costs were $28,148-$29,322; costs and health care resource use were typically higher for RR versus non-RR patients. Patients with RR AML had worse health-related quality of life (HRQoL) scores than patients with de novo AML across multiple instruments, and lower health utility values versus other AML health states (i.e. newly diagnosed, remission, consolidation, and maintenance therapy). The clinical efficacy SLR identified 50 trials (66 total trial arms). CR/CRi rates and mOS have remained relatively stable and low over the last 2 decades. Across all arms, the median rate of CR/CRi was 18.3% and mOS was 6.2 months. In conclusion, a substantial proportion of patients with AML will develop RR AML, which is associated with significant humanistic and economic burden. Existing treatments offer limited efficacy, highlighting the need for more effective non-intensive treatment options.

The Activation of Endothelial Cells Relies on a Ferroptosis-Like Mechanism: Novel Perspectives in Management of Angiogenesis and Cancer Therapy.

The activation of endothelial cells (ECs) is a crucial step on the road map of tumor angiogenesis and expanding evidence indicates that a pro-oxidant tumor microenvironment, conditioned by cancer metabolic rewiring, is a relevant controller of this process. Herein, we investigated the contribution of oxidative stress-induced ferroptosis to ECs activation. Moreover, we also addressed the anti-angiogenic effect of Propranolol. We observed that a ferroptosis-like mechanism, induced by xCT inhibition with Erastin, at a non-lethal level, promoted features of ECs activation, such as proliferation, migration and vessel-like structures formation, concomitantly with the depletion of reduced glutathione (GSH) and increased levels of oxidative stress and lipid peroxides. Additionally, this ferroptosis-like mechanism promoted vascular endothelial cadherin (VE-cadherin) junctional gaps and potentiated cancer cell adhesion to ECs and transendothelial migration. Propranolol was able to revert Erastin-dependent activation of ECs and increased levels of hydrogen sulfide (H2S) underlie the mechanism of action of Propranolol. Furthermore, we tested a dual-effect therapy by promoting ECs stability with Propranolol and boosting oxidative stress to induce cancer cell death with a nanoformulation comprising selenium-containing chrysin (SeChry) encapsulated in a fourth generation polyurea dendrimer (SeChry@PUREG4). Our data showed that novel developments in cancer treatment may rely on multi-targeting strategies focusing on nanoformulations for a safer induction of cancer cell death, taking advantage of tumor vasculature stabilization.

Targeted therapy for inherited GPI deficiency.

Disrupted binding of the transcription factor Sp1 to the mutated promoter region of the mannosyl transferase-encoding gene PIGM causes inherited glycosylphosphatidylinositol (GPI) deficiency characterized by splanchnic vein thrombosis and epilepsy. We show that this results in histone hypoacetylation at the promoter of PIGM. The histone deacetylase inhibitor butyrate increases PIGM transcription and surface GPI expression in vitro as well as in vivo through enhanced histone acetylation in an Sp1-dependent manner. More important, the drug caused complete cessation of intractable seizures in a child with inherited GPI deficiency.

Monocytes as Endothelial Progenitor Cells (EPCs), Another Brick in the Wall to Disentangle Tumor Angiogenesis.

Bone marrow contains endothelial progenitor cells (EPCs) that, upon pro-angiogenic stimuli, migrate and differentiate into endothelial cells (ECs) and contribute to re-endothelialization and neo-vascularization. There are currently no reliable markers to characterize EPCs, leading to their inaccurate identification. In the past, we showed that, in a panel of tumors, some cells on the vessel wall co-expressed CD14 (monocytic marker) and CD31 (EC marker), indicating a putative differentiation route of monocytes into ECs. Herein, we disclosed monocytes as potential EPCs, using in vitro and in vivo models, and also addressed the cancer context. Monocytes acquired the capacity to express ECs markers and were able to be incorporated into blood vessels, contributing to cancer progression, by being incorporated in tumor neo-vasculature. Reactive oxygen species (ROS) push monocytes to EC differentiation, and this phenotype is reverted by cysteine (a scavenger and precursor of glutathione), which indicates that angiogenesis is controlled by the interplay between the oxidative stress and the scavenging capacity of the tumor microenvironment.

Vorinostat synergizes with antioxidant therapy to target myeloproliferative neoplasms.

BCR-ABL-negative myeloproliferative neoplasms (MPNs) are driven by JAK-STAT pathway activation, but epigenetic alterations also play an important pathophysiological role. These can be pharmacologically manipulated with histone deacetylase inhibitors (HDACIs), which have proven to be clinically effective in the treatment of MPNs but exhibit dose-limiting toxicity. The treatment of primary MPN cells with vorinostat modulates the expression of genes associated with apoptosis, cell cycle, inflammation, and signaling. The induction of this transcriptional program results in decreased cellular viability, paralleled by a decrease in levels of reactive oxygen species (ROS). In vitro manipulation of ROS levels revealed that the reduction of ROS levels promoted apoptosis. When vorinostat was combined with antioxidant agents, the apoptosis of MPN cells increased in a synergistic manner. The results described here suggest a novel and promising therapeutic strategy combining HDACIs with ROS-reducing agents to treat MPNs.

Everolimus in combination with Imatinib overcomes resistance in Chronic myeloid leukaemia.

Although Imatinib and other tyrosine kinase inhibitors (TKIs) have excellent results, the appearance of resistance is a problem in chronic myeloid leukaemia (CML). PI3K/AKT/mTOR pathway is activated by BCR-ABL playing a crucial rule in CML. This study aimed to evaluate the therapeutic potential of Everolimus, in CML models sensitive and resistant to Imatinib. We used one CML cell line sensitive to Imatinib (K562) and two resistant (K562-RC and K56-RD). Cell lines were treated with Everolimus alone and in combination with Imatinib. Cell viability was analysed by resazurin assay. Cell death and cell cycle were analysed by flow cytometry. Additionally, we also studied peripheral blood samples obtained from 52 patients under TKI treatment. Everolimus reduced cell line viability in sensitive (IC50 = 20 µM) and resistant models (K562-RC, IC50 = 25 µM; K562-RD, IC50 = 30 µM). This drug induced cell death by apoptosis and cell cycle arrest in G0/G1 phase. Everolimus also reduced cell viability by increasing apoptosis of haematopoietic stem cells (CD34+ cells) with low cytotoxicity to lymphocytes. Everolimus at 25 µM increased apoptotic cells 18.7% in CD34+ cells and only 8% in lymphocytes. The response to Everolimus was influenced by TKI treatment, with a better response in samples from patients under 2nd and 3rd generation TKI and with less toxicity to lymphocytes. Our results reveal that Everolimus induce cell death in CML cells sensitive and resistant to Imatinib, with low cytotoxicity to normal cells, suggesting that Everolimus could be an alternative targeted therapeutic approach in CML patients, even in cases of Imatinib resistance.

MicroRNA signature refine response prediction in CML.

microRNAs (miRs) dysregulation have emerged as a crucial step in tumorigenesis, being related with cancer development, progression and response to treatment. In chronic myeloid leukaemia (CML), the resistance to tyrosine kinase inhibitors (TKI) is responsible for treatment failure and could be linked to changes in miRs expression. This work aimed to correlate the expression levels of 3 miRs, miR-21, miR-26b and miR-451, with response to TKI treatment in CML patients. miR-451 levels at diagnosis were significantly higher in patients with optimal response after 6 and 12 months of therapy. Conversely, patients without optimal response had highest levels of miR-21. miR-21 and miR-451 appear to be good biomarkers of response, able to predict optimal TKI responders (p < 0.05). Using the combined profile of both miRs, we create a predictive model of optimal response after one year of treatment. This study highlights the role of miR-21 and miR-451 expression levels at diagnosis in predicting which patients achieve the optimal response.

MORPhA Scale: Behavioral and electroencephalographic validation of a rodent anesthesia scale.

BACKGROUND: Laboratory practice commonly implies rodent anesthesia. Such is instrumental not only for animal welfare, but also for standardized assessment of new anesthetics. NEW METHOD: We developed and validated a grading system for a temporal follow-up of anesthesia. The Minho Objective Rodent Phenotypical Anesthesia (MORPhA) scale was tested in mice (C57BL/6 J) and rats (Wistar-Han) anesthetized with ketamine/dexmedetomidine (ket/dex). The scale comprises 12 behavioral readouts organized in 5 stages - (i) normal/(ii) hindered voluntary movement, elicited response to (iii) non-noxious/(iv) noxious stimuli and (v) absence of response - evaluated at regular time-points. Progression across stages was monitored by electroencephalography (EEG) in rats during anesthesia induction and reversal (atipamezole) and during induction with a second anesthetic drug (pentobarbital). RESULTS: Higher anesthetic doses decreased the time to reach higher levels of anesthesia during progression, while increasing the time to regain waking behavior during reversal in both mice and rats. A regular decrease in high frequencies (low and high gamma) power was observed as the MORPhA score increased during anesthesia induction, while the opposite pattern was observed during emergence from anesthesia through reversion of dex effect. COMPARISON WITH EXISTING METHODS: Degree of anesthesia in laboratory rodents is normally evaluated by testing loss of reflexes. While these are useful endpoint assessments, they are of limited application to study induction/reversal kinetics or factors affecting individual susceptibility. MORPhA allows graded standardized assessment of this progression in a biologically-relevant fashion. CONCLUSIONS: The devised anesthetic scale is of simple application and provides a semi-quantifiable readout of anesthesia induction/reversal.