Satishkumar Tala

Novel antitumor indolizino[6,7-b]indoles with multiple modes of action: DNA cross-linking and topoisomerase I and II inhibition.

A series of bis(hydroxymethyl)indolizino[6,7-b]indoles and their bis(alkylcarbamates) were synthesized for antitumor studies. These agents were designed as hybrid molecules of β-carboline (topoisomerase inhibition moiety) and bis(hydroxymethyl)pyrrole (DNA cross-linking moiety). The preliminary antitumor studies indicated that these agents exhibited significant cytotoxicity against a variety of human tumor cells in vitro. Treatment of human breast carcinoma MX-1 xenograft-bearing nude mice with compounds 18b and 28c achieved more than 99% tumor remission. We also observed that 18a displayed potent therapeutic efficacy against human lung adenocarcinoma A549 and colon cancer HT-29 xenografts. These results revealed that compound 18a was more potent than irinotecan against HT-29 cells and was as potent as irinotecan against A549 cells in xenograft models. Furthermore, we demonstrated that these derivatives possess multiple modes of action, such as induction of DNA cross-linking, inhibition of topoisomerase I and II, and cell-cycle arrest at the S-phase.

A Potent Derivative of Indolizino[6,7-b]Indole for Treatment of Human Non-Small Cell Lung Cancer Cells.

The therapeutic effect in non–small cell lung cancer (NSCLC) patients is limited because of intrinsic and acquired resistance. Thus, an unmet need exists for the development of new drugs to improve the therapeutic efficacy in NSCLC patients. In this study, the novel small molecule indolizino[6,7-b]indole derivative BO-1978 was selected to evaluate its therapeutic effects on NSCLC and its preclinical toxicity in animal models. An in vitro cytotoxicity assay revealed that BO-1978 significantly suppressed the growth of various NSCLC cell lines with or without mutations in epidermal growth factor receptor (EGFR). Mechanistically, we demonstrated that BO-1978 exhibited multiple modes of action, including inhibition of topoisomerase I/II and induction of DNA cross-linking. Treatment of NSCLC cells with BO-1978 caused DNA damage, disturbed cell cycle progression, and triggered apoptotic cell death. Furthermore, BO-1978 significantly suppressed the growth of EGFR wild-type and mutant NSCLC tumors in xenograft tumor and orthotopic lung tumor models with negligible body weight loss. The combination of BO-1978 with gefitinib further suppressed EGFR mutant NSCLC cell growth in xenograft tumor and orthotopic lung tumor models. Preclinical toxicity studies showed that BO-1978 administration did not cause apparent toxicity in mice. Based on its significant therapeutic efficacy and low drug toxicity, BO-1978 is a potential therapeutic agent for treatment of NSCLC.

Design and synthesis of potent antitumor water-soluble phenyl N-mustard-benzenealkylamide conjugates via a bioisostere approach.

A series of new, water-soluble phenyl N-mustard-benzenealkylamide conjugates containing hydrophilic ω-dialkylaminoalkylamide or ω-cyclic aminoalkylamide moieties were synthesized via a bioisostere approach. These compounds have a broad spectrum of antitumor activity against a panel of human tumor cell lines. Of these derivatives, compound 18b effectively suppressed the growth of colon cancer (HCT-116), prostate cancer (PC3), and lung cancer (H460) xenografts. The growth of HCT-116 xenografts was almost completely suppressed when co-treated with compound 18b and 5-fluorouracil. Furthermore, compound 18b can induce DNA cross-linking and cell-cycle arrest at the G2/M phase. Early preclinical studies, including pharmacokinetics in rats, inhibition of the hERG, and 14 days of acute intravenous injection toxicity, suggest that compound 18b is a promising candidate for further preclinical studies.

Corrigendum to “PI3K Inhibition Augments the Therapeutic Efficacy of a 3a–aza-Cyclopenta[α]indene Derivative in Lung Cancer Cells [Translational Oncology 7 (2014) 256–266.e5]

*Molecular Medicine Program, Taiwan International Graduate Program, Academia Sinica, Taipei, Taiwan; Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan; Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan; Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan

Corrigendum to “A Potent Derivative of Indolizino[6,7-b]Indole for Treatment of Human Non–Small Cell Lung Cancer Cells” [Neoplasia 18 (2016) 199-212]

The authors regret to have mistakenly placed the figure of body weight change in mice treated with different agents in PC9 cells (Figure 6A, right) with that of PC9/gef B4 cells (Figure 6B, right) during the art work. The corrected Figure 6 was attached below. The authors would like to apologize for any inconvenience caused.

PI3K Inhibition Augments the Therapeutic Efficacy of a 3a-aza-Cyclopenta[α]indene Derivative in Lung Cancer Cells

The synergistic targeting of DNA damage and DNA repair is a promising strategy for the development of new chemotherapeutic agents for human lung cancer. The DNA interstrand cross-linking agent BO-1509, a derivative of 3a-aza-cyclopenta[α]indene, was synthesized and combined with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 to treat human lung cancer cells. Our results showed that the BO-1509 and LY294002 combination synergistically killed lung cancer cells in culture and also suppressed the growth of lung cancer xenografts in mice, including those derived from gefitinib-resistant cells. We also found that LY294002 suppressed the induction of several DNA repair proteins by BO-1509 and inhibited the nuclear translocation of Rad51. On the basis of the results of the γH2AX foci formation assays, LY294002 apparently inhibited the repair of DNA damage that was induced by BO-1509. According to the complete blood profile, biochemical enzyme analysis, and histopathologic analysis of major organs, no apparent toxicity was observed in mice treated with BO-1509 alone or in combination with LY294002. Our results suggest that the combination of a DNA cross-linking agent with a PI3K inhibitor is a feasible strategy for the treatment of patients with lung cancer.

Abstract 1694: Combination of Indolizino[6,7-b]indole and Gefitinib synergistically suppresses the growth of EGFR-mutant NSCLC cells

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA We have previously revealed that indolizino[6,7-b]indoles are effective antitumor agents against a variety of cancer cells. Indolizino[6,7-b]indoles were shown to induce DNA crosslinks and inhibit the enzymatic activities of topoisomerase I and II. Our recent results demonstrated that the derivatives of indolizino[6,7-b]indoles potently suppressed the cell growth of several non-small cell lung cancer (NSCLC) cells, including H460, PC9, PC9/gef B4, and H1975 cells in in vitro and in vivo systems. We also showed that BO-1978, one of indolizino[6,7-b]indole derivatives, completely suppressed the growth of CL1-5/GFP-Luciferase and PC9/gef B4-Luciferase cells in orthotopic lung cancer models. These results implicated that indolizino[6,7-b]indoles are potential candidate agents against NSCLC. EGFR mutations are frequently occurred in NSCLC. Although targeted agents such as Gefitinib is effectively suppression the growth of NSCLC with EGFR mutations, the resistance to Gefitinib is quickly developed and causes the failure of targeted treatments. Since the combination of targeted agents and cytotoxic drugs is one of strategies to overcome the problem encountered by targeted therapy, we further explore the therapeutic potential of combination of BO-1978 and Gefitinib against EGFR-mutant NSCLC. Our results showed that the combination treatment of PC9 and PC9/gef B4 cells with BO-1978 and Gefitinib resulted in synergistic induction of apoptosis and suppression of cell growth in cultured cells. We also confirmed the therapeutic efficacy of combined treatment of PC9 and PC9/gef B4 cells with BO-1978 and Gefitinib in xenografted tumor models. Since we did not observe severe body weight loss in mice received the combination treatment of BO-1978 and Gefitinib, our present studies apparently support that BO-1978 and its combination with Gefitinib is highly prospective as therapeutic agents against EGFR-mutant NSCLC. Citation Format: Chi-Wei Chen, Satishkumar Tala, Tsann-Long Su, Te-Chang Lee. Combination of Indolizino[6,7-b]indole and Gefitinib synergistically suppresses the growth of EGFR-mutant NSCLC cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1694. doi:10.1158/1538-7445.AM2014-1694

Abstract B259: Novel indolizino[6,7-b]indoles suppress the growth of human non-small cell lung cancer cells in xenografted and orthotopic mouse models via induction of DNA crosslinks and inhibition of topoisomerase I and II.

Non-small cell lung cancer (NSCLC) remains a global health problem due to the limited therapeutic responses and drug resistance. We have previously demonstrated that indolizino[6,7-b]indoles are potent antitumor agents with DNA cross-linking and topoisomerase I and II inhibition activities (JMC, 56: 1544-1563, 2013). The present study explores its therapeutic activity against NSCLC. Our results showed that BO-1922 and BO-1978, the selected derivatives of indolizino[6,7-b]indoles, effectively repressed the cell growth of several NSCLC lines, including as H460 (KRAS mutation), H1299 (TP53 deficient), A549 (KRAS mutation), CL141T (TP53 mutation), PC9 (EGFR mutation), PC9/gef B4 (EGFR mutation and acquired resistant to TKI), CL100 (EGFR mutation), and CL97 (EGFR mutation and acquired resistant to TKI). Using mouse xenograft models, we found that BO-1922 and BO-1978 could significantly suppress the tumor growth of H460, PC9, and PC9/gef B4 in mice. Furthermore, we demonstrated that these 2 compounds could remarkably inhibit the growth of CL1-5/GFP-Luciferase cells in orthotopic lung cancer model. In addition, we performed preclinical toxicity studies. Accordingly, the LD50 of BO-1922 and BO-1978 to ICR mice are 77.4 and 93.7 mg/kg, respectively. Based on blood cell counts, blood biochemistry, histopathological examination of major organs, BO-1922 and BO-1978 did not cause obvious toxicity at the doses of 20 and 40 mg/kg on day 2 and 14 after injections. Taken together, our present study revealed that BO-1922 and BO-1978 are highly prospective leads for treatment of NSCLC. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B259. Citation Format: Chi-Wei Chen, Yi-Fan Chen, Shu-Hsin Chao, Satishkumar Tala, Tsann-Long Su, Te-Chang Lee. Novel indolizino[6,7- b ]indoles suppress the growth of human non-small cell lung cancer cells in xenografted and orthotopic mouse models via induction of DNA crosslinks and inhibition of topoisomerase I and II. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B259.

Abstract B253: Novel water-soluble phenyl N-mustard-benzenealkylamide conjugate, BO-2094, potent agent for treatment of human colorectal cancer.

Colorectal cancer (CRC) is the second leading cause of cancer related death in the United States and Europe. Surgery, radiotherapy, and chemotherapy are the main strategies for cure of CRC patient. However, the mortality risk associated with CRC is metastasis, which may be diminished by systemic treatments. Therefore, there is an urgent need of finding a better agent to treat CRC. Recently, we have synthesized a series of novel water soluble and chemically stable phenyl N-mustard- benzenealkylamide conjugates, which is consisted of phenyl N-mustard pharmacophore and benzenealkylamide moiety bearing a variety of hydrophilic alkylamide side chains. Of these conjugates, BO-2094 exhibits a broad spectrum of antitumor activity against a panel of human leukemia and solid tumor cell lines in vitro and potent therapeutic efficacy in various tumor xenograft-moles. This agent is able to induce DNA interstrand cross-linking, cell cycle arrest at sub-G1 and G2/M phase, and cell death via apoptosis. Particularly, BO-2094 displays potent antitumor activity in nude mice bearing human colon cancer HCT-116 and H334 xenografts. More than 95% tumor suppression was observes when BO-2094 [30 mg/kg, once per day for 6 consecutive days (QD×6), via intravenous injection (iv. inj.)] was used alone. The combination of BO-2094 and 5-FU at ratios of 1:3 induced synergistic cytotoxicity to HCT-116 cells in vitro. Notable, the growth of HCT-116 xenografts in nude mice was almost completely suppressed (>98% suppression) when co-treated compound BO-2094 (30 mg/kg, QD×6, iv. inj.) with 5-FU [75 mg/kg, every 7 days for 2 doses (Q7D×2), intraperitoneal injection (ip. inj.)]; all mice (n=5) survived on day 35. The results revealed that the combination of BO-2094+5-FU is superior to that of oxaliplatin [15 mg/kg every 3 days for 3 doses (Q3D×3), iv. inj.] and 5-FU [75 mg/kg, Q7D×2, ip. inj.]. It should be noted that 2 of 5 mice died on day 28 when mice were co-treated with oxaliplatin+5-FU, indicating that the combination of BO-2094+5-FU is less toxic to the host. The early preclinical studies of BO-2094 showed that this agent is likely to have no cardiac arrhythmic side effect based on hERG assay and has low toxicity to the drug treated mice based on a 14-day acute iv injection study. The present studies indicate that the combination of compound BO-2094+5-FU has great potential benefit for the treatment of advanced colon cancer. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B253. Citation Format: Tung-Hu Tsai, Satishkumar D. Tala, Tai-Hsin Ou, Yi-Wen Lin, Kiranben S. Tala, Ming-Hsi Wu, Te-Chang Lee, Tsann-Long Su. Novel water-soluble phenyl N-mustard-benzenealkylamide conjugate, BO-2094, potent agent for treatment of human colorectal cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B253.

Abstract 4475: New water-soluble and stable N-mustard-benzeneconjugates with potent antitumor activity, BO-2094, generated via leadoptimization by bioisostere approach.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC The water solubility of drug candidate plays an important determinant of the bioavailability and supports whether a drug candidate can be successfully developed for clinical application. Previously, we have synthesized a series of water-soluble N-mustards, in which the phenyl N-mustard pharmacophore is linked to a benzamide moiety containing a hydrophilic side-chain at the meta- or para-position of the carboxamide function via a urea spacer. Of these derivatives, the water-soluble BO-1055 HCl exhibits a broad spectrum of antitumor activity and potent therapeutic efficacy against various human solid tumor (such as breast MX-1, colon HCT-116, and prostate PC-3) xenografts. To optimize the antitumor activity of BO-1055 via structural modification by bioisostere approach, we synthesized a series of new N-mustard-benzene conjugates, in which the phenyl N-mustard pharmacophore is linked to a benzene moiety via a urea linker, which can reduce the reactivity of the reactive N-mustard moiety. The benzene ring contains a variety of ω-N,N-dialkylaminoalkylamide or ω-cyclicaminoalkylamide side-chains at the meta- or para-position of the ureido linker. The tertiary amino function on the side-chain can be converted into a variety of water-soluble salts with inorganic or organic acids. The newly synthesized conjugates were subject to antitumor studies both in vitro and in tumor xenograft model. The results showed that these water-soluble conjugates exhibit a broad spectrum of antitumor activity against a panel of human leukemia and solid tumor cell growth in culture. Among these derivatives, BO-2094 [N-(4-(3-(4-(bis(2-chloroethyl)amino)phenyl)ureido)phenyl)-2-(diethylamino)acetamide], was revealed to be more cytotoxic than BO-1055 in inhibiting various tumor cell growth in vitro. It also showed that this agent is more potent than BO-1055 against human colon HCT-116, prostate PC3, and lung cancer H460 xenografts in mice. Studies on the mechanism of action revealed that BO-2094 is able to induce DNA cross-linking and cell arrest at G2/M phase. The present investigations conclude that BO-2094, a new water-soluble N-mustard-benzene conjugated with more potent therapeutic effect than BO-1055, has high potential to be selected as a candidate for preclinical antitumor studies. Citation Format: Tsann-Long Su, Satishkumar Tala, Tai-Hsin Ou, Kiranben Tala, Rajesh Kakadiya, Yi-wen Lin, Chi-Wei Chen, Te-Chang Lee. New water-soluble and stable N -mustard-benzeneconjugates with potent antitumor activity, BO-2094, generated via leadoptimization by bioisostere approach. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4475. doi:10.1158/1538-7445.AM2013-4475