Pyrimidine depletion enhances targeted and immune therapy combinations in acute myeloid leukemia.

Acute myeloid leukemia (AML) is a fatal disease characterized by the accumulation of undifferentiated myeloblasts, and agents that promote differentiation have been effective in this disease but are not curative. Dihydroorotate dehydrogenase inhibitors (DHODHi) have the ability to promote AML differentiation and target aberrant malignant myelopoiesis. We introduce HOSU-53, a DHODHi with significant monotherapy activity, which is further enhanced when combined with other standard-of-care therapeutics. We further discovered that DHODHi modulated surface expression of CD38 and CD47, prompting the evaluation of HOSU-53 combined with anti-CD38 and anti-CD47 therapies, where we identified a compelling curative potential in an aggressive AML model with CD47 targeting. Finally, we explored using plasma dihydroorotate (DHO) levels to monitor HOSU-53 safety and found that the level of DHO accumulation could predict HOSU-53 intolerability, suggesting the clinical use of plasma DHO to determine safe DHODHi doses. Collectively, our data support the clinical translation of HOSU-53 in AML, particularly to augment immune therapies. Potent DHODHi to date have been limited by their therapeutic index; however, we introduce pharmacodynamic monitoring to predict tolerability while preserving antitumor activity. We additionally suggest that DHODHi is effective at lower doses with select immune therapies, widening the therapeutic index.

Pain screening in youth with sickle cell disease: A quality improvement study.

BACKGROUND: Youth with sickle cell disease (SCD) face several challenges as they age, including increased pain frequency, duration, and interference. The purpose of this study was to (i) determine the feasibility of routine pain screening; (ii) identify and describe various clinical pain presentations; and (iii) understand preferences/resources related to engaging in integrative health and medicine (IHM) modalities within an outpatient pediatric SCD clinic. METHODS: During routine outpatient visits, patients aged 8-18 completed measures of pain frequency, duration, and chronic pain risk (Pediatric Pain Screening Tool [PPST]). Participants screening positive for (i) persistent or chronic pain or (ii) medium or high risk for persistent symptoms and disability on the PPST were asked to complete measures of pain interference, pain catastrophizing, and interest in/resources for engaging in IHM modalities. RESULTS: Between March 2022 and May 2023, 104/141 (73.8%) patients who attended at least one outpatient visit were screened. Of these 104 (mean age 12.46, 53.8% female, 63.5% HbSS), 34 (32.7%) reported persistent or chronic pain, and 48 (46.2%) reported medium or high risk for persistent symptoms and disability. Patients completing subsequent pain screening measures reported a mean pain interference T-score of 53.2 ± 8.8 and a mean pain catastrophizing total score of 24.3 ± 10.2. Patients expressed highest interest in music (55.6%) and art therapy (51.9%) and preferred in-person (81.5%) over virtual programming (22.2%). CONCLUSIONS: Comprehensive pain screening is feasible within pediatric SCD care. Classifying patients by PPST risk may provide a means of triaging patients to appropriate services to address pain-related psychosocial factors.

Melanoma-associated mutants within the serine-rich domain of PAK5 direct kinase activity to mitogenic pathways.

The overexpression and hyperactivity of p21-activated serine/threonine kinases (PAKs) is known to facilitate tumorigenesis; however, the contribution of cancer-associated PAK mutations to tumor initiation and progression remains unclear. Here, we identify p21-activated serine/threonine kinase 5 (PAK5) as the most frequently altered PAK family member in human melanoma. More than 60% of melanoma-associated PAK5 gene alterations are missense mutations, and distribution of these variants throughout the protein coding sequence make it difficult to distinguish oncogenic drivers from passengers. To address this issue, we stably introduced the five most common melanoma-associated PAK5 missense mutations into human immortalized primary melanocytes (hMELTs). While expression of these mutants did not promote single-cell migration or induce temozolomide resistance, a subset of variants drove aberrant melanocyte proliferation. These mitogenic mutants, PAK5 S364L and D421N, clustered within an unstructured, serine-rich domain of the protein and inappropriately activated ERK and PKA through kinase-independent and -dependent mechanisms, respectively. Together, our findings establish the ability of mutant PAK5 to enhance PKA and MAPK signaling in melanocytes and localize the engagement of mitogenic pathways to a serine-rich region of PAK5.