Characterization of a dual BET/HDAC inhibitor for treatment of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is resistant to virtually all chemo- and targeted therapeutic approaches. Epigenetic regulators represent a novel class of drug targets. Among them, BET and HDAC proteins are central regulators of chromatin structure and transcription, and preclinical evidence suggests effectiveness of combined BET and HDAC inhibition in PDAC. Here, we describe that TW9, a newly generated adduct of the BET inhibitor (+)-JQ1 and class I HDAC inhibitor CI994, is a potent dual inhibitor simultaneously targeting BET and HDAC proteins. TW9 has a similar affinity to BRD4 bromodomains as (+)-JQ1 and shares a conserved binding mode, but is significantly more active in inhibiting HDAC1 compared to the parental HDAC inhibitor CI994. TW9 was more potent in inhibiting tumor cell proliferation compared to (+)-JQ1, CI994 alone or combined treatment of both inhibitors. Sequential administration of gemcitabine and TW9 showed additional synergistic antitumor effects. Microarray analysis revealed that dysregulation of a FOSL1-directed transcriptional program contributed to the antitumor effects of TW9. Our results demonstrate the potential of a dual chromatin-targeting strategy in the treatment of PDAC and provide a rationale for further development of multitarget inhibitors.

Synthesis and Antiproliferative Effect of Ethyl 4-[4-(4-Substituted Piperidin-1-yl)]benzylpyrrolo[1,2-a]quinoxalinecarboxylate Derivatives on Human Leukemia Cells.

Acute leukemia is a hematological malignancy with high incidence and recurrence rates and is characterized by an accumulation of blasts in bone marrow due to proliferation of immature lymphoid or myeloid cells associated with a blockade of differentiation. The heterogeneity of leukemia led us to look for new specific molecules for leukemia subtypes or for therapy-resistant cases. Among heterocyclic derivatives that attracted attention due to their wide range of biological activities, we focused our interest on the pyrrolo[1,2-a]quinoxaline heterocyclic framework that has been previously identified as an interesting scaffold for antiproliferative activities against various human cancer cell lines. In this work, new ethyl 4-[4-(4-substituted piperidin-1-yl)]benzylpyrrolo[1,2-a]quinoxalinecarboxylate derivatives (1 a-o) were designed, synthesized, and evaluated against five different leukemia cell lines, including Jurkat and U266 (lymphoid cell lines) and K562, U937, and HL60 (myeloid cell lines), as well as on normal human peripheral blood mononuclear cells (PBMCs). This new pyrrolo[1,2-a]quinoxaline series showed interesting cytotoxic potential against all tested leukemia cell lines. In particular, pyrroloquinoxalines 1 a and 1 m,n seem to be interesting due to their high activity against leukemia and their low activity against normal hematopoietic cells, leading to a high index of selectivity.

Synthesis and evaluation of the cytotoxic activity of novel ethyl 4-[4-(4-substitutedpiperidin-1-yl)]benzyl-phenylpyrrolo[1,2-a]quinoxaline-carboxylate derivatives in myeloid and lymphoid leukemia cell lines.

Leukemia is the most common blood cancer, and its development starts at diverse points, leading to distinct subtypes that respond differently to therapy. This heterogeneity is rarely taken into account in therapies, so it is still essential to look for new specific drugs for leukemia subtypes or even for therapy-resistant cases. Among heterocyclic compounds that attracted a lot of attention because of its wide spread biological activities, the pyrrolo[1,2-a]quinoxaline heterocyclic framework has been identified as interesting scaffolds for antiproliferative activity against various human cancer cell lines. In the present study, novel ethyl 4-[4-(4-substitutedpiperidin-1-yl)]benzyl-phenylpyrrolo[1,2-a]quinoxaline-carboxylate derivatives 1a-l have been designed and synthesized. Their cytotoxicities were evaluated against five different leukemia cell lines, including Jurkat and U266 (lymphoid cell lines), and K562, U937, HL60 (myeloid cell lines), as well as normal human peripheral blood mononuclear cells (PBMNCs). Then, apoptosis study was performed with the more interesting compounds. The new pyrrolo[1,2-a]quinoxaline series showed promising cytotoxic potential against all leukemia cell lines tested, and some compounds showed better results than the reference compound A6730. Some compounds, such as 1a, 1e, 1g and 1h are promising because of their high activity against leukemia and their low activity against normal hematopoietic cells. Structure-activity relationships of these new synthetic compounds 1a-l are here also discussed.

Synthesis and evaluation of the antiproliferative activity of novel isoindolo[2,1-a]quinoxaline and indolo[1,2-a]quinoxaline derivatives.

A novel series of isoindolo[2,1-a]quinoxaline and indolo[1,2-a]quinoxaline derivatives was synthesized and evaluated in vitro against various human cancer cell lines for antiproliferative activity. These new compounds displayed activity against leukemia and breast cancer cell lines in the 3- to 18-µM concentration range.