A multiparametric niche-like drug screening platform in acute myeloid leukemia.

Functional precision medicine in AML often relies on short-term in vitro drug sensitivity screening (DSS) of primary patient cells in standard culture conditions. We designed a niche-like DSS assay combining physiologic hypoxia (O2 3%) and mesenchymal stromal cell (MSC) co-culture with multiparameter flow cytometry to enumerate lymphocytes and differentiating (CD11/CD14/CD15+) or leukemic stem cell (LSC)-enriched (GPR56+) cells within the leukemic bulk. After functional validation of GPR56 expression as a surrogate for LSC enrichment, the assay identified three patterns of response, including cytotoxicity on blasts sparing LSCs, induction of differentiation, and selective impairment of LSCs. We refined our niche-like culture by including plasma-like amino-acid and cytokine concentrations identified by targeted metabolomics and proteomics of primary AML bone marrow plasma samples. Systematic interrogation revealed distinct contributions of each niche-like component to leukemic outgrowth and drug response. Short-term niche-like culture preserved clonal architecture and transcriptional states of primary leukemic cells. In a cohort of 45 AML samples enriched for NPM1c AML, the niche-like multiparametric assay could predict morphologically (p = 0.02) and molecular (NPM1c MRD, p = 0.04) response to anthracycline-cytarabine induction chemotherapy. In this cohort, a 23-drug screen nominated ruxolitinib as a sensitizer to anthracycline-cytarabine. This finding was validated in an NPM1c PDX model.

The Folate Cycle Enzyme MTHFR Is a Critical Regulator of Cell Response to MYC-Targeting Therapies.

Deciphering the impact of metabolic intervention on response to anticancer therapy may elucidate a path toward improved clinical responses. Here, we identify amino acid-related pathways connected to the folate cycle whose activation predicts sensitivity to MYC-targeting therapies in acute myeloid leukemia (AML). We establish that folate restriction and deficiency of the rate-limiting folate cycle enzyme MTHFR, which exhibits reduced-function polymorphisms in about 10% of Caucasians, induce resistance to MYC targeting by BET and CDK7 inhibitors in cell lines, primary patient samples, and syngeneic mouse models of AML. Furthermore, this effect is abrogated by supplementation with the MTHFR enzymatic product CH3-THF. Mechanistically, folate cycle disturbance reduces H3K27/K9 histone methylation and activates a SPI1 transcriptional program counteracting the effect of BET inhibition. Our data provide a rationale for screening MTHFR polymorphisms and folate cycle status to nominate patients most likely to benefit from MYC-targeting therapies. SIGNIFICANCE: Although MYC-targeting therapies represent a promising strategy for cancer treatment, evidence of predictors of sensitivity to these agents is limited. We pinpoint that folate cycle disturbance and frequent polymorphisms associated with reduced MTHFR activity promote resistance to BET inhibitors. CH3-THF supplementation thus represents a low-risk intervention to enhance their effects.See related commentary by Marando and Huntly, p. 1791.This article is highlighted in the In This Issue feature, p. 1775.

Humulane and germacrane sesquiterpenes from Ferula lycia.

Five new juniferol esters (1-5), along with six known humulane derivatives (6-11), were isolated from the roots of Ferula lycia, an endemic Turkish species. The fruits of the same species were also investigated and led to the isolation of these same compounds, as well as two known germacrane esters (12 and 13). All isolated sesquiterpenes were assayed for cytotoxicity against two tyrosine kinase inhibitor-resistant cell lines, K562R and DA1-3b/M2(BCR-ABL). The two most active compounds, juniferinin (7) and 6-beta-p-hydroxybenzoyloxygermacra-1(10),4-diene (12), were moderately active against Raji lymphoma cells but also displayed some toxicity against healthy bone marrow cells.

Activity of ladanein on leukemia cell lines and its occurrence in Marrubium vulgare.

Three methoxylated flavones isolated from Marrubium peregrinum - ladanein, scutellarein-5,7,4'-trimethyl ether, and scutellarein-5,6,7,4'-tetramethyl ether - were assayed for their cytotoxicity towards a recently developed dasatinib-resistant murine leukemia cell line (DA1-3b/M2 (BCR-ABL)), together with the structurally related non-methylated flavone scutellarein. The most active compound, ladanein, was looked for in 20 common Lamiaceae species by a quick HPLC screening. Among the possible positive results, the most interesting source was found to be Marrubium vulgare, which led to the isolation and identification of ladanein for the first time in this species. Ladanein also displayed moderate (20-40 microM) activities against K562, K562R (imatinib-resistant), and 697 human leukemia cell lines but was toxic neither to MOLM13 nor to human peripheral blood mononuclear cells. This work provides a common natural source for the hemi-synthesis of future ladanein-derived flavones and the study of their antileukemic activity.

Activity of elaeochytrin A from Ferula elaeochytris on leukemia cell lines.

Phytochemical investigation of the roots of Ferula elaeochytris made it possible to isolate two sesquiterpene esters, 6-anthraniloyljaeschkeanadiol (elaeochytrin A) and 4beta-hydroxy-6alpha-(p-hydroxybenzoyloxy)dauc-9-ene (elaeochytrin B), as well as eight known compounds: 6-angeloyljaeschkeanadiol, teferidin, ferutinin, 6-(p-hydroxybenzoyl)epoxyjaeschkeanadiol, 6-(p-hydroxybenzoyl)lancerotriol, 5-caffeoylquinic acid, 1,5-dicaffeoylquinic acid and sandrosaponin IX. The cytotoxic activities of all compounds were investigated on K562R (imatinib-resistant) human chronic myeloid leukaemia and DA1-3b/M2(BCR-ABL) (dasatinib-resistant) mouse leukemia cell line. Elaeochytrin A was the most active compound on both cell lines (IC(50)=12.4 and 7.8microM, respectively). It was also tested on non-resistant human promyelocytic leukemia cells (HL60, IC(50)=13.1microM) and was not toxic to normal peripheral blood mononuclear cells up to 100microM.