Background Glucocorticoids and asparaginase, used to treat acute lymphoblastic leukemia (ALL), can cause hypertriglyceridemia. We compared triglyceride levels, risk factors, and associated toxicities in two ALL trials at St. Jude Children's Research Hospital with identical glucocorticoid regimens, but different asparaginase formulations. In Total XV (TXV), native Escherichia coli l‐asparaginase was front‐line therapy versus the pegylated formulation (PEG‐asparaginase) in Total XVI (TXVI). Procedure Patients enrolled on TXV (n = 498) and TXVI (n = 598) were assigned to low‐risk (LR) or standard/high‐risk (SHR) treatment arms (ClinicalTrials.gov identifiers: NCT00137111 and NCT00549848). Triglycerides were measured four times and were evaluable in 925 patients (TXV: n = 362; TXVI: n = 563). The genetic contribution was assessed using a triglyceride polygenic risk score (triglyceride‐PRS). Osteonecrosis, thrombosis, and pancreatitis were prospectively graded. Results The largest increase in triglycerides occurred in TXVI SHR patients treated with dexamethasone and PEG‐asparaginase (4.5‐fold increase; P <1 × 10−15). SHR patients treated with PEG‐asparaginase (TXVI) had more severe hypertriglyceridemia (>1000 mg/dL) compared to native l‐asparaginase (TXV): 10.5% versus 5.5%, respectively (P = .007). At week 7, triglycerides did not increase with dexamethasone treatment alone (LR patients) but did increase with dexamethasone plus asparaginase (SHR patients). The variability in triglycerides explained by the triglyceride‐PRS was highest at baseline and declined with therapy. Hypertriglyceridemia was associated with osteonecrosis (P = .0006) and thrombosis (P = .005), but not pancreatitis (P = .4). Conclusion Triglycerides were affected more by PEG‐asparaginase than native l‐asparaginase, by asparaginase more than dexamethasone, and by drug effects more than genetics. It is not clear whether triglycerides contribute to thrombosis and osteonecrosis or are biomarkers of the toxicities.

Eradicating cancer stem-like cells (CSC) may be essential to fully eradicate cancer. Metabolic changes in CSC could hold a key to their targeting. Here we report that the dietary micronutrient selenium can trigger apoptosis of CSC derived from chronic or acute myelogenous leukemias when administered at supraphysiological but non-toxic doses. In leukemia CSC, selenium treatment activated ATM-p53-dependent apoptosis accompanied by increased intracellular levels of reactive oxygen species. Importantly, the same treatment did not trigger apoptosis in hematopoietic stem cells. Serial transplantation studies with BCR-ABL-expressing CSC revealed that the selenium status in mice was a key determinant of CSC survival. Selenium action relied upon the endogenous production of the cyclooxygenase-derived prostaglandins Δ12-PGJ2 and 15d-PGJ2. Accordingly, non-steroidal anti-inflammatory drugs and NADPH oxidase inhibitors abrogated the ability of selenium to trigger apoptosis in leukemia CSC. Our results reveal how selenium-dependent modulation of arachidonic acid metabolism can be directed to trigger apoptosis of primary human and murine CSC in leukemia.

Key Points Endogenous CyPG PGJ2 targets LSCs through PPARγ activation. Selenium supplementation could serve as an adjunct therapy for CML.

Background Osteonecrosis is a common toxicity associated with glucocorticoid (e.g., dexamethasone and prednisone) treatment of children with acute lymphoblastic leukemia (ALL), but risk factors are incompletely defined. Infections are also a common complication of ALL therapy. Lipopolysaccharide (LPS) is used experimentally to mimic infection‐related systemic effects. To our knowledge, the contribution of systemic infections to the risk of glucocorticoid‐induced osteonecrosis has not been investigated. Procedure Patients with ALL on St. Jude Total Therapy XV (n = 365) were assessed for documented bacteremia prior to development of osteonecrosis, which was confirmed by MRI, and graded using the National Cancer Institute's Common Terminology for Adverse Events (version 3.0). In a preclinical model, Balb/cJ mice treated with dexamethasone plus or minus LPS were assessed for frequency and severity of osteonecrosis and arteriopathy. Results We found that patients with ALL who experienced bacteremia had a higher frequency of symptomatic osteonecrosis (≥grade 2) than those who did not (OR: 1.88; 95% CI, 1.03–3.41, P = 0.038). LPS exacerbated experimental dexamethasone‐induced osteonecrosis. Mice treated with dexamethasone plus LPS had a higher incidence of osteonecrosis (P = 0.00086) and arteriopathy (P = 0.0047) than did those treated with dexamethasone alone, and the severity of osteonecrosis (P = 0.00045) and arteriopathy (P = 0.0048) was also more pronounced with the addition of LPS treatment. The increase in osteonecrosis was not explained by any alteration of dexamethasone pharmacokinetics by LPS. Conclusions These data identify systemic infection during ALL therapy as a novel risk factor in the development of glucocorticoid‐induced osteonecrosis.

Background Osteonecrosis is a devastating side effect of acute lymphoblastic leukemia (ALL) therapy. Associations between bone density loss and osteonecrosis have sparked interest in using bisphosphonates to reduce this complication. Procedure We assessed the impact of zoledronic acid (ZA) on the development of osteonecrosis in murine models when used either throughout therapy (continuous administration) or late in therapy after vascular lesions have developed but before osteonecrosis has occurred. Effects on bone density were measured using microcomputed tomography (μCT)‐assessed tibial cortical thickness, while osteonecrosis was assessed histologically in the distal femur. Effects on antileukemic efficacy of chemotherapy were evaluated in both immunocompetent/syngeneic and patient‐derived xenograft (PDX) models. Results Continuous administration of ZA with chemotherapy prevented chemotherapy‐associated bone loss (p < .001) and reduced osteonecrosis (p = .048). Late initiation of ZA diminished bone loss (p < .001) but had no impact on the development of osteonecrosis (p = .93). In the immunocompetent murine ALL model, mice treated with ZA and chemotherapy succumbed to leukemia sooner than mice treated with chemotherapy alone (p = .046). Analysis using PDX showed a nonsignificant decrease in survival with ZA (p = .17). Conclusion Our data indicate ZA may prevent osteonecrosis if begun with chemotherapy but showed no benefit when administered later in therapy. However, ZA may also reduce the antileukemic efficacy of chemotherapy.

Recent clinical trials in children with acute lymphoblastic leukemia (ALL) indicate that severe hypertriglyceridemia (>1000 mg/dL) during therapy is associated with an increased frequency of symptomatic osteonecrosis. Interventions to lower triglycerides have been considered, but there have been no preclinical studies investigating the impact of lowering triglycerides on osteonecrosis risk, nor whether such interventions interfere with the antileukemic efficacy of ALL treatment. We utilized our clinically relevant mouse model of dexamethasoneinduced osteonecrosis to determine whether fenofibrate decreased osteonecrosis. To test whether fenofibrate affected the antileukemic efficacy of dexamethasone, we utilized a BCR-ABL+ model of ALL. Serum triglycerides were reduced by fenofibrate throughout the period of treatment, with the most pronounced, 4.5-fold, decrease at week 3 ( P <1x10-6). Both frequency (33% vs . 74%, P =0.006) and severity (median necrosis score of 0 vs . 75; P =6x10-5) of osteonecrosis were reduced with fenofibrate. Fenofibrate had no impact on BCR-ABL+ ALL survival ( P =0.65) nor on the antileukemic properties of dexamethasone ( P =0.49). These data suggest that lowering triglycerides with fenofibrate reduces dexamethasone- induced osteonecrosis while maintaining antileukemic efficacy, and thus may be considered for clinical trials.

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Current therapies for treatment of myeloid leukemia do not eliminate leukemia stem cells (LSC), leading to disease relapse. In this study, we supplemented mice with eicosapentaenoic acid (EPA, C20:5), a polyunsaturated omega-3 fatty acid, at pharmacological levels, to examine if the endogenous metabolite, cyclopentenone prostaglandin delta-12 PGJ3 (Δ12-PGJ3), was effective in targeting LSCs in experimental leukemia. EPA supplementation for eight weeks resulted in enhanced endogenous production of Δ12-PGJ3 that was blocked by indomethacin, a cyclooxygenase inhibitor. Using a murine model of chronic myelogenous leukemia (CML) induced by bone marrow transplantation of BCR-ABL-expressing hematopoietic stem cells, mice supplemented with EPA showed a decrease in the LSC population, reduced splenomegaly and leukocytosis, when compared to mice on an oleic acid diet. Supplementation of CML mice carrying the T315I mutation (in BCR-ABL) with EPA resulted in a similar effect. Indomethacin blocked the EPA effect and increased the severity of BCR-ABL-induced CML and decreased apoptosis. Δ12-PGJ3 rescued indomethacin-treated BCR-ABL mice and decreased LSCs. Inhibition of hematopoietic-prostaglandin D synthase (H-PGDS) by HQL-79 in EPA-supplemented CML mice also blocked the effect of EPA. In addition, EPA supplementation was effective in a murine model of acute myeloid leukemia. Supplemented mice exhibited a decrease in leukemia burden and a decrease in the LSC colony-forming unit (LSC-CFU). The decrease in LSCs was confirmed through serial transplantation assays in all disease models. The results support a chemopreventive role for EPA in myeloid leukemia, which is dependent on the ability to efficiently convert EPA to endogenous cyclooxygenase-derived prostanoids, including Δ12-PGJ3.