Sarwat Chowdhury

Discovery and optimization of indoles and 7-azaindoles as Rho kinase (ROCK) inhibitors (part-I).

Rho kinase (ROCK) inhibitors are potential therapeutic agents to treat disorders such as hypertension, multiple sclerosis, cancers, and glaucoma. Here, we disclose the synthesis, optimization, biological evaluation of potent indole and 7-azaindole based ROCK inhibitors that have high potency on ROCK (IC(50)=1 nM) with 740-fold selectivity over PKA (47). Moreover, 47 showed very good DMPK properties making it a good candidate for further development. Finally, docking studies with a homology model of ROCK-II were performed to rationalize the binding mode of these compounds and showed the compounds bound in both orientations to take advantage to H-bonds with Lys-121 of ROCK-II.

Identification of Small-Molecule Inhibitors of the Colorectal Cancer Oncogene Krüppel-Like Factor 5 Expression by Ultrahigh-Throughput Screening

The transcription factor Krüppel-like factor 5 (KLF5) is primarily expressed in the proliferative zone of the mammalian intestinal epithelium, where it regulates cell proliferation. Studies showed that inhibition of KLF5 expression reduces proliferation rates in human colorectal cancer cells and intestinal tumor formation in mice. To identify chemical probes that decrease levels of KLF5, we used cell-based ultrahigh-throughput screening (uHTS) to test compounds in the public domain of NIH, the Molecular Libraries Probe Production Centers Network library. The primary screen involved luciferase assays in the DLD-1/pGL4.18hKLF5p cell line, which stably expressed a luciferase reporter driven by the human KLF5 promoter. A cytotoxicity counterscreen was done in the rat intestinal epithelial cell line, IEC-6. We identified 97 KLF5-selective compounds with EC50 < 10 μmol/L for KLF5 inhibition and EC50 > 10 μmol/L for IEC-6 cytotoxicity. The two most potent compounds, CIDs (PubChem Compound IDs) 439501 and 5951923, were further characterized on the basis of computational, Western blot, and cell viability analyses. Both of these compounds, and two newly synthesized structural analogs of CID 5951923, significantly reduced endogenous KLF5 protein levels and decreased viability of several colorectal cancer cell lines without any apparent impact on IEC-6 cells. Finally, when tested in the NCI-60 panel of human cancer cell lines, compound CID 5951923 was selectively active against colon cancer cells. Our results show the feasibility of uHTS in identifying novel compounds that inhibit colorectal cancer cell proliferation by targeting KLF5. Mol Cancer Ther; 10(11); 2043–51. ©2011 AACR.

Synthesis and biological evaluation of 4-quinazolinones as Rho kinase inhibitors

Rho kinase (ROCK) is an attractive therapeutic target for various diseases including glaucoma, hypertension, and spinal cord injury. Herein, we report the development of a series of ROCK-II inhibitors based on 4-quinazolinone and quinazoline scaffolds. SAR studies at three positions of the quinazoline core led to the identification of analogs with high potency against ROCK-II and good selectivity over protein kinase A (PKA).

The development of benzimidazoles as selective rho kinase inhibitors

Rho Kinase (ROCK) is a serine/threonine kinase whose inhibition could prove beneficial in numerous therapeutic areas. We have developed a promising class of ATP-competitive inhibitors based upon a benzimidazole scaffold, which show excellent potency toward ROCK (IC(50)<10nM). This report details the optimization of selectivity for ROCK over other related kinases such as Protein kinase A (PKA).

Amino acid derived quinazolines as Rock/PKA inhibitors.

SAR and lead optimization studies for Rock inhibitors based on amino acid-derived quinazolines are described. Studies demonstrated that these amino acid derived quinazolinones were mainly pan-Rock (I & II) inhibitors. While selectivity against other kinases could be achieved, selectivity for most of these compounds against PKA was not achieved. This is distinct from Rock inhibitors based on non-amino acid derived quinazolinones, where high selectivity against PKA could be obtained.(22) The inhibitors presented here in some cases possessed sub-nanomolar inhibition of Rock, nanomolar potency in ppMLC cell based assays, low to fair cytochrome P-450 inhibition, and good human microsomal stability.

Tu1894 Ultrahigh-Throughput Screening Strategies for Identification of Small-Molecule Compounds That Target the Colon Cancer Oncogene KrüPpel-Like Factor 5

Aim: The aim of the present study was to evaluate whether chronomodulated administration of capecitabine would reduce toxicity of the drug in patients with metastatic colorectal cancer. Patients & Methods: 27 patients with advanced colorectal cancer were randomized to receive capecitabine (2500mg/KOF daily) either in standard administration with 50% of the dose in themorning and 50% in the evening separated by 12 hours or as chronomodulated dose-regime with 25% morning-dose and 75% late evening-dose. Treatment was continued until thirteen treatment-cycles were finished or progress of cancer or limitation of therapy due to side effects occurred. Results: Overall, response rates to chemotherapy were similar in both treatment groups (p= 0,296). However, within the group of patients with chronomodulated application of capecitabine, reduction of drug-doses due to side effects was less frequently necessary (14.8 vs. 19.3%, p=0,026) and more patients were able to finish all thirteen chemotherapy-cycles (41.7 vs. 7.1%, p=0,007). While there was no statistically significant difference in the frequency of hand-foot-syndrome in both treatment-arms (51.7 vs. 41.5%, p=0,119) other side effects as nightly nausea, tiredness and sleeplessness were significantly reduced in patients receiving chronomodulated therapy (p=0,035, p=0,001 and 0,009, respectively). Additionally, there was a trend to lower frequency of nausea, diarrhea and stomatitis within this group compared to standard treatment (9.0 vs. 19.5%, 19.1 vs. 25.6%, and 4.5 vs. 8.5%) Conclusion: The chronomodulated capecitabine schedule achieved similar response rate and better tolerability regarding various side effects compared with standard application of the drug in patients with colorectal cancer. This schedule could enable patients to sustain on capecitabine therapy for a longer time-period.