Nanomolar-potency small molecule inhibitor of STAT5 protein

© 2014 American Chemical Society. We herein report the design and synthesis of the first nanomolar binding inhibitor of STAT5 protein. Lead compound 13a, possessing a phosphotyrosyl-mimicking salicylic acid group, potently and selectively binds to STAT5 over STAT3, inhibits STAT5-SH2 domain complexation events in vitro, silences activated STAT5 in leukemic cells, as well as STAT5's downstream transcriptional targets, including MYC and MCL1, and, as a result, leads to apoptosis. We believe 13a represents a useful probe for interrogating STAT5 function in cells as well as being a potential candidate for advanced preclinical trials

Sofosbuvir/Velpatasvir Is Effective and Safe in Patients with Concomitant Proton PUMP Inhibitor Use in Clinical Studies

BACKGROUND: Prior to the availability of Phase 1 drug interaction data, concomitant proton pump inhibitor (PPI) use was prohibited in clinical trials of Sofosbuvir/Velpatasvir (SOF/VEL). Later, clinical studies allowed use of up to 20 mg omeprazole or equivalent dosing. PURPOSE: This analysis evaluated the efficacy and safety of patients with and without compensated cirrhosis who received SOF/VEL for 12 weeks and reported concomitant use of a PPI. METHODS: This was a retrospective analysis of efficacy and safety data from 12 Phase 2 and Phase 3 clinical studies where patients of all genotypes with and without compensated cirrhosis received 12 weeks of SOF/VEL and reported concomitant use of a PPI. Efficacy was assessed by sustained virologic response 12 weeks after treatment (SVR12) and relapse rates and safety was assessed by treatment- emergent adverse events (AEs). RESULT(S): 87 patients reported concomitant use of a PPI. The mean age (range) was 57 years (26- 78), 79% were male and 75% white; 56% of patients were infected with HCV genotype 3 and 29% with genotype 1; 37% of patients had compensated cirrhosis and 39% were treatment experienced. The most common PPI was omeprazole (68% of patients). SVR12 was 97% (84 of 87 patients). Of the 3 patients who did not achieve SVR12, 2 patients relapsed (relapse rate 2%) and one patient with history of diabetes discontinued SOF/VEL after 7 days of dosing due to hyperglycemia. No other patient had an AE leading to discontinuation or interruption of SOF/VEL. 78% of patients had an AE, most of which were mild, and 11% had a serious AE. These efficacy and safety values are comparable to patients enrolled in the same studies who received SOF/VEL for 12 weeks without concomitant use of a PPI (SVR12 97% [2,445 of 2,517 patients]; relapse rate 2% [40 of 2488 patients]). CONCLUSION(S): In Phase 2 and Phase 3 clinical studies, SOF/VEL for 12 weeks was effective and safe in patients with concomitant PPI use. These data support the use of SOF/VEL according to labeled recommendations with respect to co-administration of PPIs and other acid reducing agents

Isolation and characterization of the cDNA encoding human DNA methyltransferase.

We have cloned a series of overlapping cDNA clones encoding a 5194 bp transcript for human DNA methyltransferase (DNA MTase). This sequence potentially codes for a protein of 1495 amino acids with a predicted molecular weight of 169 kDa. The human DNA MTase cDNA has eighty percent homology at the nucleotide level, and the predicted protein has seventy-four percent identity at the amino acid level, to the DNA MTase cDNA cloned from mouse cells. Like the murine DNA MTase, the amino terminal two-thirds of the human protein contains a cysteine-rich region suggestive of a metal-binding domain. The carboxy terminal one-third of the protein shows considerable similarity to prokaryotic (cytosine-5)-methyltransferases. The arrangement of multiple motifs conserved in the prokaryotic genes is preserved in the human DNA MTase, including the relative position of a proline-cysteine dipeptide thought to be an essential catalytic site in all (cytosine-5)-methyltransferases. A single 5.2 kb transcript was detected in all human tissues tested, with the highest levels of expression observed in RNA from placenta, brain, heart and lung. DNA MTase cDNA clones were used to screen a chromosome 19 genomic cosmid library. The DNA MTase-positive cosmids which are estimated to span a genomic distance of 93 kb have been localized to 19p13.2-p13.3 by fluorescence in situ hybridization. Isolation of the cDNA for human DNA MTase will allow further study of the regulation of DNA MTase expression, and of the role of this enzyme in establishing DNA methylation patterns in both normal and neoplastic cells

Combined targeting of STAT3 and STAT5: a novel approach to overcome drug resistance in chronic myeloid leukemia

In chronic myeloid leukemia, resistance against BCR-ABL1 tyrosine kinase inhibitors can develop because of BCR-ABL1 mutations, activation of additional pro-oncogenic pathways, and stem cell resistance. Drug combinations covering a broad range of targets may overcome resistance. CDDO-Me (bardoxolone methyl) is a drug that inhibits the survival of leukemic cells by targeting different pro-survival molecules, including STAT3. We found that CDDO-Me inhibits proliferation and survival of tyrosine kinase inhibitor-resistant BCR-ABL1+ cell lines and primary leukemic cells, including cells harboring BCR-ABL1T315I or T315I+ compound mutations. Furthermore, CDDO-Me was found to block growth and survival of CD34+/CD38 leukemic stem cells (LSC). Moreover, CDDO-Me was found to produce synergistic growth-inhibitory effects when combined with BCR-ABL1 tyrosine kinase inhibitors. These drug-combinations were found to block multiple signaling cascades and molecules, including STAT3 and STAT5. Furthermore, combined targeting of STAT3 and STAT5 by shRNA and STAT5-targeting drugs also resulted in synergistic growth-inhibition, pointing to a new efficient concept of combinatorial STAT3 and STAT5 inhibition. However, CDDO-Me was also found to increase the expression of heme-oxygenase-1, a heat-shock-protein that triggers drug resistance and cell survival. We therefore combined CDDO-Me with the heme-oxygenase-1 inhibitor SMA-ZnPP, which also resulted in synergistic growth-inhibitory effects. Moreover, SMA-ZnPP was found to sensitize BCR-ABL1+ cells against the combination ‘CDDO-Me+ tyrosine kinase inhibitor. Together, combined targeting of STAT3, STAT5, and heme-oxygenase-1 overcomes resistance in BCR-ABL1+ cells, including stem cells and highly resistant sub-clones expressing BCR-ABL1T315I or T315I-compound mutations. Whether such drug-combinations are effective in tyrosine kinase inhibitor-resistant patients with chronic myeloid leukemia remains to be elucidated.(VLID)485768

Nanomolar-Potency Small Molecule Inhibitor of STAT5 Protein

We herein report the design and synthesis of the first nanomolar binding inhibitor of STAT5 protein. Lead compound <b>13a</b>, possessing a phosphotyrosyl-mimicking salicylic acid group, potently and selectively binds to STAT5 over STAT3, inhibits STAT5–SH2 domain complexation events <i>in vitro</i>, silences activated STAT5 in leukemic cells, as well as STAT5′s downstream transcriptional targets, including <i>MYC</i> and <i>MCL1</i>, and, as a result, leads to apoptosis. We believe <b>13a</b> represents a useful probe for interrogating STAT5 function in cells as well as being a potential candidate for advanced preclinical trials