Lysosomal acid lipase A modulates leukemia stem cell response to venetoclax/tyrosine kinase inhibitor combination therapy in blast phase chronic myeloid leukemia.

The treatment of blast phase chronic myeloid leukemia (bpCML) remains a challenge due at least in part to drug resistance of leukemia stem cells (LSCs). Recent clinical evidence suggests that the BCL-2 inhibitor venetoclax in combination with ABL-targeting tyrosine kinase inhibitors (TKIs) can eradicate bpCML LSCs. In this report, we employed preclinical models of bpCML to investigate the efficacy and underlying mechanism of LSC-targeting with venetoclax/TKI combinations. Transcriptional analysis of LSCs exposed to venetoclax and dasatinib revealed upregulation of genes involved in lysosomal biology, in particular lysosomal acid lipase A (LIPA), a regulator of free fatty acids. Metabolomic analysis confirmed increased levels of free fatty acids in response to venetoclax/dasatinib. Pre-treatment of leukemia cells with bafilomycin, a specific lysosome inhibitor, or genetic perturbation of LIPA, resulted in increased sensitivity of leukemia cells toward venetoclax/dasatinib, implicating LIPA in treatment resistance. Importantly, venetoclax/dasatinib treatment does not affect normal stem cell function, suggestive of a leukemia-specific response. These results demonstrate that venetoclax/dasatinib is an LSCselective regimen in bpCML and that disrupting LIPA and fatty acid transport enhances venetoclax/dasatinib response in targeting LSCs, providing a rationale for exploring lysosomal disruption as an adjunct therapeutic strategy to prolong disease remission.

Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium.

Acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL-2, creating a therapeutic opportunity to target LSCs using the BCL-2 inhibitor venetoclax. While venetoclax-based regimens have shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug-responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e. OXPHOS) status with relatively high levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in LSCs and provide an avenue for clinical management of venetoclax resistance.

Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium.

We previously reported that acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL2, creating a therapeutic opportunity to target LSCs using the BCL2 inhibitor drug venetoclax. While venetoclax-based regimens have indeed shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence mechanisms that dictate venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e., OXPHOS) status with relatively high steady-state levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake sharply reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in the biology of LSCs and provide a therapeutic avenue for clinical management of venetoclax resistance.

A Novel Type of Monocytic Leukemia Stem Cell Revealed by the Clinical Use of Venetoclax-Based Therapy.

The BCL2 inhibitor venetoclax has recently emerged as an important component of acute myeloid leukemia (AML) therapy. Notably, use of this agent has revealed a previously unrecognized form of pathogenesis characterized by monocytic disease progression. We demonstrate that this form of disease arises from a fundamentally different type of leukemia stem cell (LSC), which we designate as monocytic LSC (m-LSC), that is developmentally and clinically distinct from the more well-described primitive LSC (p-LSC). The m-LSC is distinguished by a unique immunophenotype (CD34-, CD4+, CD11b-, CD14-, CD36-), unique transcriptional state, reliance on purine metabolism, and selective sensitivity to cladribine. Critically, in some instances, m-LSC and p-LSC subtypes can co-reside in the same patient with AML and simultaneously contribute to overall tumor biology. Thus, our findings demonstrate that LSC heterogeneity has direct clinical significance and highlight the need to distinguish and target m-LSCs as a means to improve clinical outcomes with venetoclax-based regimens. SIGNIFICANCE: These studies identify and characterize a new type of human acute myeloid LSC that is responsible for monocytic disease progression in patients with AML treated with venetoclax-based regimens. Our studies describe the phenotype, molecular properties, and drug sensitivities of this unique LSC subclass. This article is featured in Selected Articles from This Issue, p. 1949.

Cost and Return on Investment of a Team-Based Palliative Care Program for Parkinson Disease.

Implementation of palliative care (PC) in neurology settings may improve symptom control and quality of life and reduce acute care admissions. The benefits of team-based PC for patients with Parkinson disease have been established through rigorous evidence standards including randomized controlled trials. However, evidence on implementation costs and return on investment (ROI) is unknown and may guide other providers and systems considering this model of care. We applied time-driven activity-based costing with reimbursable visits calculated using Medicare reimbursement rates in Colorado and current procedural technology codes to 2 outpatient clinics at the University of Colorado Hospital: neurology PC and movement disorders. Per-patient ROI was calculated as the ratio of the incremental difference in financial revenues divided by the incremental difference in investment to expand PC services. The cost per new patient was $154 and $98 for neuropalliative and movement disorders clinics, respectively. Established patient visit costs were $82 and $41 for the neuropalliative care and movement disorders clinics, respectively. The neurology PC clinic had per-patient revenue for new and established visits of $297 and $147, respectively, compared with $203 and $141 for new and established visits, respectively, at the comparator clinic. Based on our assumptions, for every $1 invested in expanding PC services, a projected $1.68 will be recouped by the hospital system for new patient visits, and $0.13 will be recouped for established patient visits. These amounts are context dependent, and a calculator was created to allow other systems to estimate costs and ROI. Our results suggest that in an academic medical setting, both neurology PC and movement disorders clinics provided increased revenue to the health system. Opportunities to improve ROI include efficient allocation of personnel to new and established visits, expanding telemedicine, and other cost offsets for complex patients not estimated in this analysis. ROI may also be greater in health systems that benefit from cost savings such as accountable care organizations. Our approach may be applied to other novel care models. Future research efforts will focus on estimating the continued sustainability of this innovative outpatient care model.

A Review of Outcome Reporting Practices after Flexor Tendon Repair in Zones 1 and 2.

Background: Outcome reporting following flexor tendon repair has historically concentrated on range of movement. Recently, there has been an increase in the use of patient-reported outcome measures (PROMs). At present, there is no agreed set of outcomes to report following flexor tendon repair. The aim of this study is to review outcome reporting practices after flexor tendon repair in zones 1 and 2. Methods: A search of Ovid MEDLINE, Ovid EMBASE and Cumulative Index to Nursing and Allied Health Literature (CINAHL) between 1 January 1980 and 31 December 2019 was performed to identify the studies that reported outcomes following the repair of flexor tendons in zones 1 and 2. Study characteristics and data with regard to the reporting of eight outcome domains was extracted: functional outcome (quantitative), functional outcome (subjective), activities of daily living (ADL), satisfaction/quality of life, post-treatment recovery, resources, aesthetics and safety. Results: A total of 94 out of 4,118 articles identified were included in the review. All studies reported range of motion using 17 different methods of measurement. Eleven studies defined measurement methods incorrectly or unclearly. Only 16 studies reported PROMs, with only one reporting data on assessment of quality of life. Eighteen studies reported time away from employment. Minimal data on resource utilisation and aesthetics were included. Conclusion: This review highlights wide heterogeneity and paucity of data reporting clinical outcomes of flexor tendon surgery. The development of a core outcome set that would ensure essential outcomes are correctly defined, measured and reported is required. Level of Evidence: Level IV (Prognostic).

Tolerability and Safety of Switching from Rituximab to Ocrelizumab: Evaluating Factors Associated with Infusion Related Reactions.

BACKGROUND: Ocrelizumab and rituximab are frequently used treatments for multiple sclerosis (MS). Data on switching from rituximab to ocrelizumab is limited. OBJECTIVES: To assess the frequency, severity, and factors of infusion related reactions (IRRs) in patients with MS who switch from rituximab to ocrelizumab, compared to those who stay on rituximab. METHODS: Prospective study on MS patients aged 18-65, on rituximab for at least 2 cycles, who either switched to ocrelizumab (switch group) or stayed on rituximab (comparator group) (n = 100 each). Participants were followed for IRRs, safety, and tolerability over 12 months. RESULTS: The proportion of IRRs in patients who continue on rituximab (14%) were similar to those who switched to ocrelizumab on Day 1 (14%; p = 1.000) and Week 24 (12%; p = 0.647) but higher than at Day 15 (4%; 0.005). The risk of IRRs for the switch group was associated with the presence of B cells (CD19 and/or CD20 counts ≥1%) increasing by 5.01 (1.49, 16.82) times on Day 1 (p = 0.007). Antidrug antibodies to ocrelizumab were not associated with IRRs. No other safety concerns were identified in switching to ocrelizumab. CONCLUSION: IRRs are similar between both groups, which suggests that it is safe to switch from rituximab to ocrelizumab.

Exploring cannabis use by patients with multiple sclerosis in a state where cannabis is legal.

BACKGROUND: Studies suggest cannabis may improve symptoms like pain and muscle spasticity in patients with multiple sclerosis (PwMS). Despite cannabis' new-found legality and availability, few studies have explored the profile of PwMS cannabis users and characteristics of their use, particularly in a state where cannabis is legal both for recreational and medicinal use. The purpose of the current study was to evaluate cannabis use among PwMS at a large academic multiple sclerosis (MS) clinic, specifically: (1) prevalence, (2) products used (e.g., cannabidiol vs Δ9-tetrahydocannabinol), (3) symptom treatment, and (4) patient characteristics. METHODS: PwMS completed questions assessing personal opinions about cannabis use, characteristics of cannabis use, MS history, and sociodemographic details, as well as the self-reported disability-Patient Determined Disease Steps (PDDS), overall quality of life-the Patient Reported Outcome Measure Information System (PROMIS-10), and cognition-the Neuro-QoL ACGC v1.0 measures. RESULTS: Thirty-eight percent (n = 96) of PwMS were current Cannabis users (CUs). Although there were no sociodemographic or clinical differences (p ≤ 0.05) between CUs and Non-Cannabis users (NUs), CUs had significantly higher median disability compared to NUs (PDDS = 2 vs. 1; p = 0.02). Among CUs, 57% categorized their use as strictly medicinal. CUs reported using cannabis most often for pain and insomnia/poor sleep and experienced greater than 60% benefit/relief from cannabis use. Over 90% of respondents desire more research on cannabis for MS, and 74% indicated they would consider using cannabis for their MS. CONCLUSION: As cannabis legalization has impacted the variety of cannabis products available, there appears to be growing numbers of PwMS using cannabis, with this study's CUs reporting use of highly efficacious products with minimal side-effects.