Novel Therapeutic Targets in Acute Myeloid Leukemia (AML).

PURPOSE OF REVIEW: This review seeks to identify and describe novel genetic and protein targets and their associated therapeutics currently being used or studied in the treatment of acute myeloid leukemia (AML). RECENT FINDINGS: Over the course of the last 5-6 years, several targeted therapies have been approved by the FDA, for the treatment of both newly diagnosed as well as relapsed/refractory AML. These novel therapeutics, as well as several others currently under investigation, have demonstrated activity in AML and have improved outcomes for many patients. Patient outcomes in AML have slowly improved over time, though for many patients, particularly elderly patients or those with relapsed/refractory disease, mortality remains very high. With the identification of several molecular/genetic drivers and protein targets and development of therapeutics which leverage those mechanisms to target leukemic cells, outcomes for patients with AML have improved and continue to improve significantly.

Induction Chemotherapy With FOLFIRINOX Followed by Chemoradiation With Gemcitabine in Patients With Borderline-Resectable Pancreatic Ductal Adenocarcinoma.

INTRODUCTION: Perioperative therapy is standard for patients with borderline-resectable pancreatic ductal adenocarcinoma (BR-PDAC); however, an optimal neoadjuvant regimen is lacking. We assessed the efficacy of FOLFIRINOX chemotherapy followed by gemcitabine-based chemoradiation as preoperative therapy. METHODS: Patients received 4 cycles of FOLFIRINOX, followed by 6-weekly gemcitabine with concomitant intensity-modulated radiation. The primary endpoint was the R0 resection rate. Secondary outcomes included resection rate, overall-response, overall survival (OS), progression-free survival (PFS), and tolerability. The trial was terminated early due to slow accrual. A Simon's optimal two-stage phase II trial single arm design was used. The primary hypothesis of treatment efficacy was tested using a multistage group sequential inference procedure. The secondary failure time analysis endpoints were assessed using the Kaplan-Meier procedure and the Cox regression model. RESULTS: A total of 22 patients enrolled in the study, 18 (81.8%) completed neoadjuvant treatment. The bias corrected R0 rate was 55.6% (90% CI: 33.3, 68.3; P value = .16) among patients that received at least 1 cycle of FOLFIRINOX and was 80% among patients that underwent surgery. The median OS was 35.1 months. The median PFS among patients that underwent surgery was 34 months. CONCLUSION: An R0 resection rate of 55.6% is favorable. Neoadjuvant FOLFIRINOX followed by concomitant Gemcitabine with radiation was well-tolerated. NCT01897454.

Interactions of the Metalloregulatory Protein SloR from Streptococcus mutans with Its Metal Ion Effectors and DNA Binding Site.

UNLABELLED: Streptococcus mutans is the causative agent of dental caries, a significant concern for human health, and therefore an attractive target for therapeutics development. Previous work in our laboratory has identified a homodimeric, manganese-dependent repressor protein, SloR, as an important regulator of cariogenesis and has used site-directed mutagenesis to map functions to specific regions of the protein. Here we extend those studies to better understand the structural interaction between SloR and its operator and its effector metal ions. The results of DNase I assays indicate that SloR protects a 42-bp region of DNA that overlaps the sloABC promoter on the S. mutans UA159 chromosome, while electrophoretic mobility shift and solution binding assays indicate that each of two SloR dimers binds to this region. Real-time semiquantitative reverse transcriptase PCR (real-time semi-qRT-PCR) experiments were used to determine the individual base pairs that contribute to SloR-DNA binding specificity. Solution studies indicate that Mn(2+) is better than Zn(2+) at specifically activating SloR to bind DNA, and yet the 2.8-Å resolved crystal structure of SloR bound to Zn(2+) provides insight into the means by which selective activation by Mn(2+) may be achieved and into how SloR may form specific interactions with its operator. Taken together, these experimental observations are significant because they can inform rational drug design aimed at alleviating and/or preventing S. mutans-induced caries formation. IMPORTANCE: This report focuses on investigating the SloR protein as a regulator of essential metal ion transport and virulence gene expression in the oral pathogen Streptococcus mutans and on revealing the details of SloR binding to its metal ion effectors and binding to DNA that together facilitate this expression. We used molecular and biochemical approaches to characterize the interaction of SloR with Mn(2+) and with its SloR recognition element to gain a clearer picture of the regulatory networks that optimize SloR-mediated metal ion homeostasis and virulence gene expression in S. mutans. These experiments can have a significant impact on caries treatment and/or prevention by revealing the S. mutans SloR-DNA binding interface as an appropriate target for the development of novel therapeutic interventions.

RNA shielding of P65 is required to potentiate oncogenic inflammation in TET2 mutated clonal hematopoiesis.

TET2 mutations (mTET2) are common genetic events in myeloid malignancies and clonal hematopoiesis (CH). These mutations arise in the founding clone and are implicated in many clinical sequelae associated with oncogenic feedforward inflammatory circuits. However, the direct downstream effector of mTET2 responsible for the potentiation of this inflammatory circuit is unknown. To address this, we performed scRNA and scATAC-seq in COVID-19 patients with and without TET2-mutated CH reasoning that the inflammation from COVID-19 may highlight critical downstream transcriptional targets of mTET2. Using this approach, we identified MALAT1, a therapeutically tractable lncRNA, as a central downstream effector of mTET2 that is both necessary and sufficient to induce the oncogenic pro-inflammatory features of mTET2 in vivo. We also elucidate the mechanism by which mTET2 upregulate MALAT1 and describe an interaction between MALAT1 and P65 which leads to RNA "shielding" from PP2A dephosphorylation thus preventing resolution of inflammatory signaling.

Activated CLL cells regulate IL-17F-producing Th17 cells in miR155-dependent and outcome-specific manners.

Chronic lymphocytic leukemia (CLL) results from expansion of a CD5+ B cell clone that requires interactions with other cell types, including T cells. Moreover, patients with CLL have elevated levels of circulating IL-17A+ and IL-17F+ CD4+ T (Th17) cells, with higher numbers of IL-17A+ Th17 cells correlating with better outcomes. We report that CLL Th17 cells expressed more miR155, a Th17-differentiation regulator, than control Th17 cells, despite naive CD4+ T (Tn) cell basal miR155 levels being similar in both. We also found that CLL cells directly regulated miR155 levels in Tn cells, thereby affecting Th17 differentiation, by documenting that coculturing Tn cells with resting or activated (Bact) CLL cells altered the magnitude and direction of T cell miR155 levels; CLL Bact cells promoted IL-17A+ and IL-17F+ T cell generation by an miR155-dependent mechanism, confirmed by miR155 inhibition; coculture of Tn cells with CLL Bact cells led to a linear correlation between the degree and direction of T cell miR155 expression changes and production of IL-17F but not IL-17A; and Bact cell-mediated changes in Tn cell miR155 expression correlated with outcome, irrespective of IGHV mutation status, a strong prognostic indicator. These results identify a potentially unrecognized CLL Bact cell-dependent mechanism, upregulation of Tn cell miR155 expression and subsequent enhancement of IL-17F+ Th17 generation, that favors better clinical courses.