Signaling Pathways in Leukemic Stem Cells.

Hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs) utilize many of the same signaling pathways for their maintenance and survival. In this review, we will focus on several signaling pathways whose roles have been extensively studied in both HSCs and LSCs. Our main focus will be on the PI3K/AKT/mTOR pathway and several of its regulators and downstream effectors. We will also discuss several other signaling pathways of particular importance in LSCs, including the WNT/ß-catenin pathway, the NOTCH pathway, and the TGFß pathway. For each of these pathways, we will emphasize differences in how these pathways operate in LSCs, compared to their function in HSCs, to highlight opportunities for the specific therapeutic targeting of LSCs. We will also highlight areas of crosstalk between multiple signaling pathways that may affect LSC function.

Multisite Quality Improvement Initiative to Identify and Address Racial Disparities and Deficiencies in Delivering Equitable, Patient-Centered Care for Multiple Myeloma-Exploring the Differences between Academic and Community Oncology Centers.

Treatment of multiple myeloma (MM) is complex; however, with equal access to care, clinical outcomes for Black patients match those in other patient groups. To reveal and begin to address clinical practice barriers to equitable, patient-centered MM care, this quality improvement (QI) initiative assessed patient electronic medical records (EMRs) and surveyed patients and providers at two large hospital systems and four community-based practices. For the educational intervention, providers participated in feedback-focused grand rounds sessions to reflect on system barriers and develop action plans to improve MM care. EMR reviews revealed infrequent documentation of cytogenetics and disease staging at community-based practices compared to large hospital systems. In surveys, providers from each care setting reported different challenges in MM care. Notably, the goals of treatment for patients and providers aligned at community clinics while providers and patients from large hospital systems had discordant perspectives. However, providers in community settings underreported race-associated barriers to care and identified different factors impacting treatment decision-making than Black patients. Relative to pre-session responses, providers were more likely to report high confidence after the educational sessions in aligning treatment decisions with guidelines and clinical evidence and shared decision-making (SDM). This QI study identified discordant perceptions among providers at large hospital systems and community-based practices in providing quality MM care. Provider education yielded increased confidence in and commitment to patient-centered care.

Crizotinib Has Preclinical Efficacy in Philadelphia-Negative Myeloproliferative Neoplasms.

PURPOSE: The Philadelphia chromosome-negative myeloproliferative neoplasms (MPN) polycythemia vera, essential thrombocythemia, and primary myelofibrosis are characterized by JAK/STAT pathway activation. JAK inhibitors are approved for MPN treatment, but persistence has been observed, due to JAK/STAT reactivation. EXPERIMENTAL DESIGN: Using MPN patient samples, JAK2-mutated cell lines, and MPN mouse models, we examined both the efficacy and mechanism by which crizotinib, the ALK/MET/RON/ROS1 inhibitor approved for the treatment of non-small cell lung cancer, alters MPN cell proliferation and JAK/STAT activation. RESULTS: We found that crizotinib suppresses proliferation and activation of JAK/STAT signaling, and decreases the disease burden in the JAK2V617F mouse model of MPN. Furthermore, we found that crizotinib could overcome JAK inhibitor persistence to ruxolitinib. Interestingly, phosphorylation of the crizotinib target RON kinase was enhanced in ruxolitinib-persistent cells. We show that phospho-JAK2 and phospho-RON can physically interact to sustain JAK/STAT signaling, and that the combination of crizotinib and ruxolitinib disrupts this interaction. Furthermore, RON knockdown suppresses proliferation and activation of JAK/STAT signaling in JAK2-mutated cells, and RON deletion in a JAK2V617F mouse MPN model decreases the disease burden. We also observed RON hyperactivation in MPN patient cells, suggesting that RON may be an important target of crizotinib in MPN. CONCLUSIONS: In summary, we demonstrate that crizotinib has preclinical efficacy in MPN patient cells, JAK2-mutated cell lines, and a JAK2-mutated mouse model, and that the combination of crizotinib with JAK inhibitors suppresses JAK inhibitor persistence. Our work suggests that crizotinib should be investigated for the treatment of patients with MPN.