HCT116 Xenograft Model Research Articles

Discovery of novel glutaminase 1 allosteric inhibitor with 4-piperidinamine linker and aromatic heterocycles

Glutaminase 1 (GLS1) is overexpressed in multiple types of malignant tumors and is viewed as a promising target in cancer therapy. Thus, the discovery for small-molecule GLS1 inhibitors is being urgent. Based on our previous study of C147, a potent GLS1 allosteric inhibitor yet with a limited metabolic stability, a structure-based optimization was carried out, with a series of novel GLS1 allosteric inhibitors rationally designed, synthesized and biologically evaluated. Such endeavor has culminated in the identification of 41e, a promising GLS1 allosteric inhibitor with 4-piperidinamine linker and aromatic heterocycles. 41e displayed robust GLS1 binding affinity, superior liver microsome metabolic stability, and moderate anti-tumor activity (TGI: 47.5%) in HCT116 xenograft model with no considerable toxicity in vivo. The mechanism underlying the anti-proliferative effect of 41e on HCT116 cells was studied, revealing that the compound blocked the glutamine metabolism, induced the production of ROS, and triggered apoptosis. These findings merit further investigation of 41e as a targeted cancer therapeutic.

Shikonin induced Apoptosis Mediated by Endoplasmic Reticulum Stress in Colorectal Cancer Cells.

Shikonin is a naphthoquinone pigment isolated from the root of Lithospermum erythrorhizon, which has displayed potent anti-tumor properties. However, the effects of shikonin in colorectal cancer cells have not been yet fully investigated. In this study, we demonstrated that shikonin significantly inhibited the activity of colorectal cancer cells in a time- and dose-dependent manner. The flow cytometry and western blot results indicated that shikonin induced cell apoptosis by down-regulating BCL-2 and activating caspase-3/9 and the cleavage of PARP. The expression of BiP and the PERK/elF2α/ATF4/CHOP and IRE1α /JNK signaling pathways were upregulated after shikonin treatment. The pre-treatment with N-acetyl cysteine significantly reduced the cytotoxicity of shikonin. Taken together, shikonin could inhibit proliferation of the colorectal cancer cell through the activation of ROS mediated-ER stress. The in vivo results showed that shikonin effectively inhibited tumor growth in the HCT-116 and HCT-15 xenograft models. In conclusion, shikonin inhibited the proliferation of colorectal cancer cells in vitro and in vivo and warrants future investigation.

Synthesis and bioevaluation of diaryl urea derivatives as potential antitumor agents for the treatment of human colorectal cancer

The development of inhibitors targeting the PI3K-Akt-mTOR signaling pathway has been greatly hindered by the on-target AEs, such as hyperglycemia and hepatotoxicities. In this study, a series of diaryl urea derivatives has been designed and synthesized based on clinical candidate gedatolisib (6aa), and most of the newly synthesized derivatives showed kinase inhibitory and antiproliferative activities within nanomolar and submicromolar level, respectively. The terminal l-prolineamide substituted derivative 6 ab showed 8.6-fold more potent PI3Kα inhibitory activity (0.7 nM) and 4.6-fold more potent antiproliferative effect against HCT116 cell lines (0.11 μM) compared with control 6aa. The potential antitumor mechanism and efficacy of 6 ab in HCT116 xenograft models have also been evaluated, and found 6 ab showed comparable in vivo antitumor activity with 6aa. The safety investigations revealed that compound 6 ab exhibited more safer profiles in the selectivity of liver cells (selectivity index: >6.6 vs 1.85) and blood glucose regulation than 6aa. In addition, the in vitro stability assays also indicated our developed compound 6 ab possessed good metabolic stabilities.

Design, synthesis, and biological evaluation of novel covalent inhibitors targeting focal adhesion kinase

Forty-one new focal adhesion kinase (FAK) covalent inhibitors were designed and synthesized based on FAK inhibitor TAE226. Compound 11w displayed the highest inhibition of FAK with an IC50 value of 35 nM and exhibited potent anticancer activity against Hela, HCT116 and MDA-MB-231 cell lines with IC50 values of 0.41, 0.01 and 0.11 μM respectively, compared to TAE226 (2.68, 0.64 and 4.19 μM respectively). 11w also inhibited the clone formation and migration of HCT-116 cells and stimulated cell cycle arrest in the G2/M phase, inducing tumor cell apoptosis. Compound 11w formed a covalent bond with the Cys427 residue of FAK in a docking model, inhibiting the autophosphorylation of FAK and downstream proteins in a dose-dependent manner. Moreover, 11w showed adequate oral bioavailability of 21.02%. A 74.20% inhibition of tumor growth in the HCT116 xenograft model was also observed. These data indicate that 11w is a promising covalent inhibitor of FAK.

Abstract 1104: Repotrectinib increases effectiveness of MEK inhibitors in KRAS mutant cancer models

Abstract KRAS is the most frequently mutated oncogene in cancers, accounting for approximately 25% of non small cell lung cancer (NSCLC), 45% of colorectal cancer (CRC), and 75% of pancreatic cancer. KRAS G12D and G12V mutations account for a large percent of mutant KRAS cancers (36% of NSCLC; 57% of CRC; 71% of pancreatic). MEK1/2 are critical downstream effectors of KRAS signaling and preclinical studies in KRAS mutant models show sensitivity to MEK inhibitors (MEKi). However, clinical studies of single agent MEKi or combinations with docetaxel in mutant KRAS NSCLC patients were associated with low response rates. Preclinical studies show that effectiveness of MEK inhibition can be limited by multiple resistance mechanisms such as compensatory upregulation of PI3K/AKT via SRC/FAK signaling, or activation of the JAK2/STAT3 pathway. Repotrectinib is a next-generation ROS1/TRK inhibitor with SRC/FAK/JAK2 inhibitory potencies which may suppress adaptive resistance to MEK inhibitors. In the current study, repotrectinib combinations with KRAS signaling network inhibitors including MEK (trametinib, selumetinib), MEK/RAF (VS-6766), ERK (LY3214996), SHP2 (TNO155) were explored. Repotrectinib/trametinib and repotrectinib/VS-6766 combinations yielded significant effects on cancer cell viability in NSCLC and pancreatic patient-derived spheroid models harboring KRASG12D and KRASG12V mutations. The repotrectinib/trametinib combination in A427 cells (NSCLC KRASG12D) exhibited increased inhibition of pAKT and pS6 compared to single agent treatments. This coincided with greater upregulation of p27 and elevated PARP cleavage, resulting in enhanced induction of apopotosis. To assess acquired MEKi resistance, several KRAS mutant cancer models were cultured under trametinib selection. Evaluation of trametinib-resistant cancer cells revealed activation of STAT3, FAK, and AKT signaling along with elevated S6 protein phosphorylation, which could be suppressed and resensitized to trametinib by combining with repotrectinib. Repotrectinib/trametinib combination in a syngeneic GEMM KRASG12D lung model had greater tumor growth inhibition than either single agent treatment. A similar combination efficacy benefit was observed in a HCT116 (CRC KRASG13D) xenograft model concomitant with suppression of SRC/FAK/STAT3/ERK activation. Taken together, repotrectinib combinations with MEK inhibitors demonstrated enhanced efficacy in both in vitro and in vivo preclinical models. Repotrectinib was shown to suppress molecular mechanisms of adaptive resistance mechanisms to MEK inhibition in preclinical models. These results suggest that the combination of repotrectinib with MEKi can repress the mutant KRAS signaling network to achieve more potent and durable anti-tumor activity and warrants clinical investigation in patients with KRASG12D and KRASG12V mutant cancers. Citation Format: Nathan V. Lee, Wei Deng, Dayong Zhai, Laura Rodon, Ana Parra, Jessica Cowell, Afsheen Banisadr, Xin Zhang, Brion W. Murray. Repotrectinib increases effectiveness of MEK inhibitors in KRAS mutant cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1104.

Water-soluble derivatives of evodiamine: Discovery of evodiamine-10-phosphate as an orally active antitumor lead compound.

10-Hydroxyevodiamine is a multitargeting antitumor lead compound with excellent invitro activity. However, its invivo antitumor potency is rather limited, which has hampered its further clinical development. To overcome this obstacle, a series of novel water-soluble derivatives of 10-hydroxyevodiamine were designed and synthesized. Most of them exhibited good to excellent antitumor activities against several cancer cell lines. In particular, phosphate derivative 9 was orally active and showed improved invivo antitumor efficacy in HCT116 xenograft models. Further antitumor mechanism studies indicated that compound 9 acted by triple Top1/Top2/tubulin inhibition and induced apoptosis with G2/M cell cycle arrest. Taken together, this study extended the structure-activity relationship of evodiamine and identified phosphate derivative 9 as a promising antitumor lead compound.

A four-component combination derived from Huang-Qin Decoction significantly enhances anticancer activity of irinotecan.

Huang-Qin Decoction (HQD) is a classic prescription for diarrhea in Chinese medicine treatment. Recent studies have demonstrated that HQD and its modified formulation PHY906 could ameliorate irinotecan (CPT-11) induced gastrointestinal (GI) toxicity and enhance its anticancer therapeutic efficacy. Nevertheless, which constituents in HQD are effective is still unclear so far. The study aims to screen out the key bioactive components combination from HQD that could enhance the anticancer effect of CPT-11. First, the potential bioactive constituents were obtained through system pharmacology strategy. Then the bioactivity of each constituent was investigated synthetically from the aspects of NCM460 cell migration, TNF-α release of THP-1-derived macrophage and MTT assay in HCT116 cell. The contribution of each constituent in HQD was evaluated using the bioactive index Ei, which taken the content and bioactivity into comprehensive consideration. And then, the most contributing constituents were selected out to form a key-component combination. At last, the bioefficacy of the key-component combination was validated in vitro and in vivo. As a result, a key-component combination (HB4) consisting of four compounds baicalin, baicalein, glycyrrhizic acid and wogonin was screened out. In vitro assessment indicated that HB4 could enhance the effect of CPT-11 on inhibiting cell proliferation and inducing apoptosis in HCT116. Furthermore, the in vivo study confirmed that HB4 and HQD have similar pharmacological activity and could both enhance the antitumor effect of CPT-11 in HCT116 xenograft model. Meanwhile, HB4 could also reduce the CPT-11 induced GI toxicity.

Concomitant inhibition of B7-H3 and PD-L1 expression by a novel and synthetic microRNA delivers potent antitumor activities in colorectal tumor models.

The families of miR-34 and miR-449 share the same seed region. However, the members showed differential effects on the expression of B7-H3 and PD-L1 in HCT-116 cells. Using miR-34a as a template, the non-seed region was modified by nucleotide alteration, yielding four synthetic microRNA (miRNA) analogs. Among those, NS-MX3, with a base alteration from G to C at the 18th locus of miR-34a, showed the most potent inhibition on both B7-H3 and PD-L1 expression. Subsequent investigations demonstrated that NS-MX3 had a broad anti-proliferation activity against several colorectal tumor cell lines and its antitumor effect was consistently reflected by tumor growth inhibition (TGI) in the HCT-116 xenograft model. In addition, NS-MX3 displayed a synergistic effect on TGI when combined with bevacizumab or regorafenib. Further analysis revealed that the superior antitumor activity of NS-MX3 was correlated to concomitant suppression of both B7-H3 and PD-L1 expression in tumor tissues. Taken together, the present study indicates that the non-seed region of miRNAs plays an important role in the regulation of checkpoint genes, thus showcasing single nucleotide alteration of the non-seed region as a promising approach to discover and develop novel immunotherapies.

Fragment-Based Design of a Potent MAT2a Inhibitor and in Vivo Evaluation in an MTAP Null Xenograft Model.

MAT2a is a methionine adenosyltransferase that synthesizes the essential metabolite S-adenosylmethionine (SAM) from methionine and ATP. Tumors bearing the co-deletion of p16 and MTAP genes have been shown to be sensitive to MAT2a inhibition, making it an attractive target for treatment of MTAP-deleted cancers. A fragment-based lead generation campaign identified weak but efficient hits binding in a known allosteric site. By use of structure-guided design and systematic SAR exploration, the hits were elaborated through a merging and growing strategy into an arylquinazolinone series of potent MAT2a inhibitors. The selected in vivo tool compound 28 reduced SAM-dependent methylation events in cells and inhibited proliferation of MTAP-null cells in vitro. In vivo studies showed that 28 was able to induce antitumor response in an MTAP knockout HCT116 xenograft model.

Structural simplification of evodiamine: Discovery of novel tetrahydro-β-carboline derivatives as potent antitumor agents

Natural products (NPs) have played a crucial role in the discovery and development of antitumor drugs. However, the high structural complexity of NPs generally results in unfavorable physicochemical profiles and poor drug-likeness. A powerful strategy to tackle this obstacle is the structural simplification of NPs by truncating nonessential structures. Herein, a series of tetrahydro-β-carboline derivatives were designed by elimination of the D ring of NP evodiamine. Structure-activity relationship studies led to the discovery of compound 45, which displayed highly potent antitumor activity against all the tested cancer cell lines and excellent in vivo antitumor activity in the HCT116 xenograft model with low toxicity. Further mechanistic research indicated that compound 45 acted by dual Top1/2 inhibition and induced caspase-dependent cell apoptosis coupled with G2/M cell cycle arrest. This proof-of-concept study validated the effectiveness of structural simplification in NP-based drug development, discovered compound 45 as a potent antitumor lead compound and enriched the structure–activity relationships of evodiamine.

Corosolic acid inhibits colorectal cancer cells growth as a novel HER2/HER3 heterodimerization inhibitor.

Colorectal cancer is the third most common cancer worldwide. HER2 and HER3 are two members of human epidermal receptor family of tyrosine kinase receptors (RTKs) and associated with poor survival in colorectal cancer. They have been observed as important therapeutic targets in various types of cancer. Corosolic acid, a natural pentacyclic triterpene, has been demonstrated to have a significant anti-cancer activity. However, the target of corosolic acid has not yet been explored. This study aimed to reveal the direct targets of corosolic acid underlying its anti-cancer activities. The targets of corosolic acid were revealed by the phospho-RTK array, bio-layer interferometry, co-immunoprecipitation, and proximity ligation assay. The inhibitory action of corosolic acid on HER2/HER3 heterodimerization and related downstream signalling were investigated in HCT116 and SW480 cells. In addition, the chemo-preventive effects of corosolic acid were validated in both HCT116 xenograft model and AOM/DSS model. Our results demonstrated that corosolic acid could prevent NRG1-induced HER2/HER3 heterodimerization and suppress the phosphorylation of both HER2 and HER3. Furthermore, HER2 and HER3 could regulate the downstream signalling pathways of RalA/RalBP1/CDK1 and PI3K/Akt/PKA, respectively, resulting in the changes in phosphorylation of Drp1 and mitochondrial dynamics. corosolic acid exhibited anti-cancer activity in both HCT116 xenograft model and AOM/DSS model. Collectively, our results demonstrated corosolic acid directly targeted HER2 and HER3 heterodimerization and inhibited mitochondrial fission via regulating RalA/RalBP1/CDK1 and PI3K/Akt/PKA pathways, revealing a novel mechanism underlying the beneficial effects of corosolic acid on colorectal cancer.

Compensatory combination of mTOR and TrxR inhibitors to cause oxidative stress and regression of tumors.

Background: Cancer is a leading cause of death worldwide. Extensive research over decades has led to the development of therapies that inhibit oncogenic signaling pathways. The mammalian target of rapamycin (mTOR) signaling pathway plays an important role in the development of many cancers. Several mTOR inhibitors are approved for the treatment of cancers. However, the anticancer efficacies of mTOR inhibitor monotherapy are still limited.Methods: Western blot was used to detect the expression of indicated molecules. Thioredoxin reductase (TrxR) activity in cells was determined by the endpoint insulin reduction assay. Immunofluorescence staining was used to analyze precise location and expression of target proteins. Nude mice were used for xenograft tumor models.Results: We identified a synergistic lethal interaction of mTOR and TrxR inhibitors and elucidated the underlying molecular mechanisms of this synergism. We demonstrated that mTOR and TrxR inhibitors cooperated to induce cell death by triggering oxidative stress, which led to activation of autophagy, endoplasmic reticulum (ER) stress and c-Jun N-terminal Kinase (JNK) signaling pathway in cancer cells. Remarkably, we found that auranofin (AF) combined with everolimus significantly suppressed tumor growth in HCT116 and SGC-7901 xenograft models with no significant signs of toxicity.Conclusion: Our findings identify a promising therapeutic combination for cancer and has important implications for developing mTOR inhibitor-based combination treatments.

Discovery of Novel Dual Extracellular Regulated Protein Kinases (ERK) and Phosphoinositide 3-Kinase (PI3K) Inhibitors as a Promising Strategy for Cancer Therapy.

Concomitant inhibition of MAPK and PI3K signaling pathways has been recognized as a promising strategy for cancer therapy, which effectively overcomes the drug resistance of MAPK signaling pathway-related inhibitors. Herein, we report the scaffold-hopping generation of a series of 1H-pyrazolo[3,4-d]pyrimidine dual ERK/PI3K inhibitors. Compound 32d was the most promising candidate, with potent inhibitory activities against both ERK2 and PI3Kα which displays superior anti-proliferative profiles against HCT116 and HEC1B cancer cells. Meanwhile, compound 32d possessed acceptable pharmacokinetic profiles and showed more efficacious anti-tumor activity than GDDC-0980 and the corresponding drug combination (BVD-523 + GDDC-0980) in HCT-116 xenograft model, with a tumor growth inhibitory rate of 51% without causing observable toxic effects. All the results indicated that 32d was a highly effective anticancer compound and provided a promising basis for further optimization towards dual ERK/PI3K inhibitors.

Pyrido[2, 3-d]pyrimidin-7(8H)-ones as new selective orally bioavailable Threonine Tyrosine Kinase (TTK) inhibitors.

A series of pyrido [2, 3-d]pyrimidin-7(8H)-ones were designed and synthesized as new selective orally bioavailable Threonine Tyrosine Kinase (TTK) inhibitors. One of the representative compounds, 5o, exhibited strong binding affinity with a Kd value of 0.15nM, but was significantly less potent against a panel of 402 wild-type kinases at 100nM. The compound also potently inhibited the kinase activity of TTK with an IC50 value of 23nM, induced chromosome missegregation and aneuploidy, and suppressed proliferation of a panel of human cancer cell lines with low μM IC50 values. Compound 5o demonstrated good oral pharmacokinetic properties with a bioavailability value of 45.3% when administered at a dose of 25mg/kg in rats. Moreover, a combination therapy of 5o with paclitaxel displayed promising invivo efficacy against the HCT-116 human colon cancer xenograft model in nude mice with a Tumor Growth Inhibition (TGI) value of 78%. Inhibitor 5o may provide a new research tool for further validating therapeutic potential of TTK inhibition.

Vitamin D as a Primer for Oncolytic Viral Therapy in Colon Cancer Models

Oncolytic viroimmunotherapy is an exciting modality that can offer lasting anti-tumor immunity for aggressive malignancies like colon cancer. The impact of oncolytic viruses may be extended by combining them with agents to prime a tumor for viral susceptibility. This study investigates vitamin D analogue as an adjunct to oncolytic viral therapy for colon cancer. While vitamin D (VD) has historically been viewed as anti-viral, our in vitro investigations using human colon cancer cell lines showed that VD does not directly inhibit replication of recombinant chimeric poxvirus CF33. VD did restrict growth in HT29 but not HCT116 human colon cancer cells. In vivo investigations using HCT116 and HT29 xenograft models of colon cancer demonstrated that a VD analogue, calcipotriol, was additive with CF33-based viral therapy in VD-responsive HT29 but not in HCT116 tumors. Analyses of RNA-sequencing and gene expression data demonstrated a downregulation in the Jak-STAT signaling pathway with the addition of VD to viral therapy in HT29 models suggesting that the anti-inflammatory properties of VD may enhance the effects of viral therapy in some models. In conclusion, VD may prime oncolytic viral therapy in certain colon cancers.

Pharmacological activation of the p53 pathway by a new compound CYZ2017 exerts anti-tumor effects

Blockage of p53-MDM2 protein-protein interaction has long been a promising strategy of drug development for cancers with wild type p53. In this study, we report a new p53-MDM2 interaction inhibitor, CYZ2017, which could induce p53 nuclear translocation and possess p53-dependent anti-proliferation activity in a range of cancer cells. CYZ2017 treatment led to increase of p53 levels and induced the transactivation of its target genes p21. In addition, CYZ2017 induced G0/G1 cell cycle arrest and apoptosis in HCT116 cells. Besides, CYZ2017 suppressed tumor growth in a HCT116 xenograft model without visible toxicity. These results support that CYZ2017 might be a promising p53-MDM2 interaction inhibitor with good anti-tumor activity. Our finding provides some cues for further investigation of developing anti-tumor drugs based on the blockage of p53-MDM2 interaction.

Isodeoxyelephantopin Inactivates Thioredoxin Reductase 1 and Activates ROS-Mediated JNK Signaling Pathway to Exacerbate Cisplatin Effectiveness in Human Colon Cancer Cells.

Colon cancer is one of the leading causes of cancer-related death in the world. The development of new drugs and therapeutic strategies for patients with colon cancer are urgently needed. Isodeoxyelephantopin (ESI), a sesquiterpene lactone isolated from the medicinal plant Elephantopus scaber L., has been reported to exert antitumor effects on several cancer cells. However, the molecular mechanisms underlying the action of ESI is still elusive. In the present study, we found that ESI potently suppressed cell proliferation in human colon cancer cells. Furthermore, our results showed that ESI treatment markedly increased cellular reactive oxygen species (ROS) levels by inhibiting thioredoxin reductase 1 (TrxR1) activity, which leads to activation of the JNK signaling pathway and eventually cell death in HCT116 and RKO cells. Importantly, we found that ESI markedly enhanced cisplatin-induced cytotoxicity in HCT116 and RKO cells. Combination of ESI and cisplatin significantly increased the production of ROS, resulting in activation of the JNK signaling pathway in HCT116 and RKO cells. In vivo, we found that ESI combined with cisplatin significantly suppressed tumor growth in HCT116 xenograft models. Together, our study provide a preclinical proof-of-concept for ESI as a potential strategy for colon cancer treatment.

Synergistic antitumor activity of DHA and JQ1 in colorectal carcinoma

Colon cancer is still a major disease plaguing humans. In this study, we evaluated the synergistic antitumor effects of the combination of BRD4 inhibitor JQ1 and docosahexaenoic acid (DHA) in colon cancer. We demonstrated that simultaneous exposure to JQ1 and DHA resulted in strong synergistic antiproliferative and proapoptotic effects related to inhibition of expression of c-Myc and activation of NF-κB in colon cancer cell lines. At the same time, the synergetic anticancer effect had been confirmed in vivo. For in vivo experiments, JQ1 and DHA resulted in more significant tumor growth inhibition (53.7%) in a human colon cancer HCT116 xenograft model, comparing with the moderate inhibition in JQ1-treated (31.9%) or DHA-treated groups (20.3%). Because DHA is the predominant component of fish oil, our data suggest that this nontoxic dietary supplement could be administered with BRD4 inhibitor during therapy for CRC, which lay an important foundation for the development of therapeutic regimens for CRC.

Synthesis and biological study of class I selective HDAC inhibitors with NO releasing activity

Based on the multi-mechanism antitumor strategy and the regulatory effect of nitric oxide (NO) on histone deacetylases (HDACs), a series of N-acyl-o-phenylenediamine-based HDAC inhibitors equipped with the phenylsulfonylfuroxan module as NO donor was designed, synthesized and biologically evaluated. The in vitro HDAC inhibitory assays revealed that compared with the clinical class I selective HDAC inhibitor MS275, compounds 7c, 7d and 7e possessed similar HDAC inhibitory potency and selective profile, which were confirmed by the results of western blot analysis. The western blot analysis also showed that NO scavenger N-acetyl cysteine (NAC) could weaken the intracellular HDAC inhibitory ability of compound 7c, supporting the HDAC inhibitory effect of NO generated by 7c. It is worth noting that compounds 7c, 7d and 7e exhibited more potent in vitro antiproliferative activities than MS275 against all four tested solid tumor cell lines. The promising in vivo antitumor potency of 7c was demonstrated in a HCT116 xenograft model.

Identification of novel potent and non-toxic anticancer, anti-angiogenic and antimetastatic rhenium complexes against colorectal carcinoma

Combination therapy targeting both tumor growth and vascularization is considered to be a cornerstone for colorectal carcinomas (CRC) treatment. However, the major obstacles of most clinical anticancer drugs are their weak selective activity towards cancer cells and inherent inner organs toxicity, accompanied with fast drug resistance development. In our effort to discover novel selective and non-toxic agents effective against CRC, we designed, synthesized and characterized a series of rhenium(I) tricarbonyl-based complexes with increased lipophilicity. Two of these novel compounds were discovered to possess remarkable anticancer, anti-angiogenic and antimetastatic activity in vivo (zebrafish-human HCT-116 xenograft model), being effective at very low doses (1–3 μM). At doses as high as 250 μM the complexes did not provoke toxicity issues encountered in clinical anticancer drugs (cardio-, hepato-, and myelotoxicity). In vivo assays showed that the two compounds exceed the anti-tumor and anti-angiogenic activity of clinical drugs cisplatin and sunitinib malate, and display a large therapeutic window.