Healthcare providers' knowledge and attitudes about overdose prevention sites in Colorado.

BACKGROUND: Overdose prevention sites (OPS) are a harm reduction strategy that offer people who use drugs a variety of resources including but not limited to sterile supplies, linkage to healthcare resources, and intervention if an overdose occurs. OPS operate in over 120 countries and evidence has demonstrated they are an effective harm reduction strategy. Despite their success elsewhere, OPS remain federally illegal in the United States and thus there is limited research on their implementation and outcomes in the United States. This study aimed to identify Colorado healthcare providers' knowledge and attitudes about OPS and determine if there is a correlation between healthcare providers with more knowledge about OPS having a more positive attitude about OPS. METHODS: An electronic survey was distributed to healthcare providers in Colorado. Responses were collected in early 2022 and recorded on a 5-point Likert scale. Mean scores between 1 and 5 were calculated for each participant and analysis of variance methods were used to determine correlating demographic factors. A p value of ≤ 0.05 was used to determine statistical significance of all findings. RESULTS: This study included 698 participants. A Pearson correlation analysis revealed a strong positive relationship (r = 0.76, p < 0.0001) between provider knowledge and attitudes about OPS. Emergency medicine providers scored the highest in mean knowledge and attitude scores in comparison to all other specialties. Respondents affiliated with a harm reduction center exhibited the highest mean knowledge and attitude scores. Mean knowledge and attitude scores generally rose with respondents' increasing encounters with people who inject drugs in a typical workday, except when reaching nine or more encounters, where a sharp decline occurred. CONCLUSIONS: Our study highlights the importance of education, exposure to harm reduction strategies, and inter-specialty collaboration in shaping healthcare providers' knowledge and attitudes about OPS. The positive correlation between providers' knowledge and attitudes about OPS suggests that educating healthcare providers on harm reduction strategies, specifically OPS, may lead to reduced stigmatization of OPS among healthcare professionals.

Mer receptor tyrosine kinase is a therapeutic target in pre-B-cell acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is currently treated with an intense regimen of chemotherapy yielding cure rates near 85%. However, alterations to treatment strategies using available drugs are unlikely to provide significant improvement in survival or decrease therapy-associated toxicities. Here, we report ectopic expression of the Mer receptor tyrosine kinase in pre-B-cell ALL (B-ALL) cell lines and pediatric patient samples. Inhibition of Mer in B-ALL cell lines decreased activation of AKT and MAPKs and led to transcriptional changes, including decreased expression of antiapoptotic PRKCB gene and increase in proapoptotic BAX and BBC3 genes. Further, Mer inhibition promoted chemosensitization, decreased colony-forming potential in clonogenic assays, and delayed disease onset in a mouse xenograft model of leukemia. Our results identify Mer as a potential therapeutic target in B-ALL and suggest that inhibitors of Mer may potentiate lymphoblast killing when used in combination with chemotherapy. This strategy could reduce minimal residual disease and/or allow for chemotherapy dose reduction, thereby leading to improved event-free survival and reduced therapy-associated toxicity for patients with B-ALL. Additionally, Mer is aberrantly expressed in numerous other malignancies suggesting that this approach may have broad applications.

Mer receptor tyrosine kinase is a novel therapeutic target in pediatric B-cell acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is currently treated with an intense regimen of chemotherapy yielding cure rates near 80%. However, additional changes using available drugs are unlikely to provide significant improvement in survival. New therapies are warranted given the risk of severe therapy-associated toxicities including infertility, organ damage, and secondary malignancy. Here, we report ectopic expression of the receptor tyrosine kinase Mer in pediatric B-cell ALL. Inhibition of Mer prevented Erk 1/2 activation, increased the sensitivity of B-ALL cells to cytotoxic agents in vitro by promoting apoptosis, and delayed disease onset in a mouse model of leukemia. In addition, we discovered cross-talk between the Mer and mammalian target of rapamycin (mTOR) signaling pathways. Our results identify Mer as a novel therapeutic target in ALL and suggest that inhibitors of Mer will interact synergistically with currently used therapies. This strategy may allow for dose reduction resulting in decreased toxicity and increased survival rates. Mer is aberrantly expressed in numerous other malignancies suggesting that this approach may have broad applications.

Targeting paediatric acute lymphoblastic leukaemia: novel therapies currently in development.

Modifications to the treatment of acute lymphoblastic leukaemia (ALL) in children have led to a dramatic increase in survival in the past 40 years. Despite this success, a significant subset of paediatric leukaemia patients either relapse or fail to ever achieve a complete remission. Additionally, some patients necessitate treatment with intensified chemotherapy regimens due to clinical or laboratory findings which identify them as high risk. These patients are unlikely to respond to further minor adjustments to the dosing or timing of administration of the same chemotherapy medications. Many novel targeted therapies for the treatment of childhood ALL provide potential mechanisms to further improve cure rates, and provide the possibility of minimizing toxicity to non-malignant cells, given their specificity to malignant cell phenotypes. This article explores many of the potential targeted therapies in varying stages of development, from those currently in clinical trials to those still being refined in the research laboratory.

TAM receptor tyrosine kinases: biologic functions, signaling, and potential therapeutic targeting in human cancer.

Tyro-3, Axl, and Mer constitute the TAM family of receptor tyrosine kinases (RTKs) characterized by a conserved sequence within the kinase domain and adhesion molecule-like extracellular domains. This small family of RTKs regulates an intriguing mix of processes, including cell proliferation/survival, cell adhesion and migration, blood clot stabilization, and regulation of inflammatory cytokine release. Genetic or experimental alteration of TAM receptor function can contribute to a number of disease states, including coagulopathy, autoimmune disease, retinitis pigmentosa, and cancer. In this chapter, we first provide a comprehensive review of the structure, regulation, biologic functions, and downstream signaling pathways of these receptors. In addition, we discuss recent evidence which suggests a role for TAM receptors in oncogenic mechanisms as family members are overexpressed in a spectrum of human cancers and have prognostic significance in some. Possible strategies for targeted inhibition of the TAM family in the treatment of human cancer are described. Further research will be necessary to evaluate the full clinical implications of TAM family expression and activation in cancer.

Mer590, a novel monoclonal antibody targeting MER receptor tyrosine kinase, decreases colony formation and increases chemosensitivity in non-small cell lung cancer.

The successes of targeted therapeutics against EGFR and ALK in non-small cell lung cancer (NSCLC) have demonstrated the substantial survival gains made possible by precision therapy. However, the majority of patients do not have tumors with genetic alterations responsive to these therapies, and therefore identification of new targets is needed. Our laboratory previously identified MER receptor tyrosine kinase as one such potential target. We now report our findings targeting MER with a clinically translatable agent--Mer590, a monoclonal antibody specific for MER. Mer590 rapidly and robustly reduced surface and total MER levels in multiple cell lines. Treatment reduced surface MER levels by 87%, and this effect was maximal within four hours. Total MER levels were also dramatically reduced, and this persisted for at least seven days. Mechanistically, MER down-regulation was mediated by receptor internalization and degradation, leading to inhibition of downstream signaling through STAT6, AKT, and ERK1/2. Functionally, this resulted in increased apoptosis, increased chemosensitivity to carboplatin, and decreased colony formation. In addition to carboplatin, Mer590 interacted cooperatively with shRNA-mediated MER inhibition to augment apoptosis. These data demonstrate that MER inhibition can be achieved with a monoclonal antibody in NSCLC. Optimization toward a clinically available anti-MER antibody is warranted.

Prolonged exposure to a Mer ligand in leukemia: Gas6 favors expression of a partial Mer glycoform and reveals a novel role for Mer in the nucleus.

Mer tyrosine kinase is ectopically expressed in acute lymphoblastic leukemia and associated with enhanced chemoresistance and disease progression. While such effects are generally ascribed to increased engagement of oncogenic pathways downstream of Mer stimulation by its ligand, Gas6, Mer has not been characterized beyond the scope of its signaling activity. The present study explores Mer behavior following prolonged exposure to Gas6, a context similar to the Gas6-enriched microenvironment of the bone marrow, where a steady supply of ligand facilitates continuous engagement of Mer and likely sustains the presence of leukemic cells. Long-term Gas6 exposure induced production of a partially N-glycosylated form of Mer from newly synthesized stores of protein. Preferential expression of the partial Mer glycoform was associated with diminished levels of Mer on the cell surface and altered Mer localization within the nuclear-soluble and chromatin-bound fractions. The presence of Mer in the nucleus is a novel finding for this receptor, and the glycoform-specific preferences observed in each nuclear compartment suggest that glycosylation may influence Mer function within particular subcellular locales. Previous studies have established Mer as an attractive cancer biologic target, and understanding the complexity of its activity has important implications for potential strategies of Mer inhibition in leukemia therapy. Our results identify several novel features of Mer that expand the breadth of its functions and impact the development of therapeutic modalities designed to target Mer.

Taking aim at Mer and Axl receptor tyrosine kinases as novel therapeutic targets in solid tumors.

IMPORTANCE OF THE FIELD: Axl and/or Mer expression correlates with poor prognosis in several cancers. Until recently, the role of these receptor tyrosine kinases (RTKs) in development and progression of cancer remained unexplained. Studies demonstrating that Axl and Mer contribute to cell survival, migration, invasion, metastasis and chemosensitivity justify further investigation of Axl and Mer as novel therapeutic targets in cancer. AREAS COVERED IN THIS REVIEW: Axl and Mer signaling pathways in cancer cells are summarized and evidence validating these RTKs as therapeutic targets in glioblastoma multiforme, NSCLC, and breast cancer is examined. A discussion of Axl and/or Mer inhibitors in development is provided. WHAT THE READER WILL GAIN: Potential toxicities associated with Axl or Mer inhibition are addressed. We propose that the probable action of Mer and Axl inhibitors on cells within the tumor microenvironment will provide a therapeutic opportunity to target both tumor cells and the stromal components that facilitate disease progression. TAKE HOME MESSAGE: Axl and Mer mediate multiple oncogenic phenotypes and activation of these RTKs constitutes a mechanism of chemoresistance in a variety of solid tumors. Targeted inhibition of these RTKs may be effective as anti-tumor and/or anti-metastatic therapy, particularly if combined with standard cytotoxic therapies.