New insights into the role of VKORC1 polymorphisms for optimal warfarin dose selection in Caribbean Hispanic patients through an external validation of a population PK/PD model

Warfarin, an oral anticoagulant, has been used for decades to prevent thromboembolic events. The complex interplay between CYP2C9 and VKORC1 genotypes on warfarin PK and PD properties is not fully understood in special sub-groups of patients. This study aimed to externally validate a population pharmacokinetic/pharmacodynamic (PK/PD) model for the effect of warfarin on international normalized ratio (INR) and to evaluate optimal dosing strategies based on the selected covariates in Caribbean Hispanic patients. INR, and CYP2C9 and VKORC1 genotypes from 138 patients were used to develop a population PK/PD model in NONMEM. The structural definition of a previously published PD model for INR was implemented. A numerical evaluation of the parameter-covariate relationship was performed. Simulations were conducted to determine optimal dosing strategies for each genotype combinations, focusing on achieving therapeutic INR levels. Findings revealed elevated IC50 for G/G, G/A, and A/A VKORC1 haplotypes (11.76, 10.49, and 9.22 mg/L, respectively), in this population compared to previous reports. The model-guided dosing analysis recommended daily warfarin doses of 3-5 mg for most genotypes to maintain desired INR levels, although subjects with combination of CYP2C9 and VKORC1 genotypes * 2/* 2-, * 2/* 3- and * 2/* 5-A/A would require only 1 mg daily. This research underscores the potential of population PK/PD modeling to inform personalized warfarin dosing in populations typically underrepresented in clinical studies, potentially leading to improved treatment outcomes and patient safety. By integrating genetic factors and clinical data, this approach could pave the way for more effective and tailored anticoagulation therapy in diverse patient groups.

Abstract 347: Comparative activity of MBQ-167 metabolites in metastatic breast cancer

Metastasis continues to be the most difficult phase for cancer treatment due to few targeted therapy options. Therefore, we focus on targeting the Rho GTPases Rac1 and Cdc42, key drivers of the primary steps of metastasis: cell migration and invasion. We developed MBQ-167 as a small molecule dual inhibitor for Rac1 and Cdc42 activation with IC50s of 103 and 78 nM, respectively. In metastatic human breast cancer cells, MBQ-167 inhibits the Rac/Cdc42 downstream effector p21-activated kinase (PAK)/LIM kinase/Cofilin signaling, lamellipodia extension, and thus, cell polarity, and migration. In addition, in metastatic breast cancer cells, MBQ-167 inhibits cell proliferation and cell cycle progression to ultimately induce apoptosis via anoikis. MBQ-167 inhibits tumor growth and metastasis in experimental and spontaneous HER-positive and Triple negative breast cancer (TNBC) mouse models. MBQ-167 has 35% bioavailability and is not toxic in rodent or canine models up to 1000 mg/kg. Therefore, we are further developing MBQ-167 as a lead anti metastatic cancer compound. The objective in this study is to elucidate potential activity of MBQ-167 metabolites. Prior work has identified MBQ-167 metabolites via LC MS/MS from a mammalian liver microsome (rats and human) assay. Four of the MBQ-167 metabolites with the highest MS peak area, were analyzed in metastatic breast cancer cell lines, for cell viability via MTT assays and apoptosis via caspase 3/7 assays. We report that the metabolites M6, M7, M8, and M9 did not inhibit cell viability or induce apoptosis at 250 or 500 nM in HER2-type MDA-MB-435, and TNBC MDA-MB-231 and MDA-MB-468 breast cancer cell lines, compared to MBQ-167. We next analyzed whether these metabolites could inhibit the activation of Rac and Cdc42 by analyzing the phosphorylation status of its downstream effector p-21 activated kinase isoforms 1/2/3 (PAK1/2/3). When MBQ-167 and metabolites at 250nM were incubated for 24h in HER2-type MDA-MB-435 metastatic cancer cells, and the lysates western blotted with antibodies to total PAK1/2/3 or phospho-Pak1/2/3, we found a decrease in the phosphorylation levels of PAK in response to MBQ-167 and metabolite M6. However, since the peak area of M6 in the microsome assay is only 6% compared to MBQ-167, we conclude that MBQ-167 is the major active compound with anti-metastatic cancer properties.

Citation Format: Julia I. Medina, Eliud Hernández, Cornelis Vlaar, Suranganie Dharmawardhane. Comparative activity of MBQ-167 metabolites in metastatic breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 347.

Abstract 2973: Rac inhibitors for cancer therapy

Among all cancers worldwide, breast cancer is the first cause of death in women. One of the most aggressive subtypes of breast cancer is the triple negative form, which account for the 10-15% of breast cancer cases. Due to its complex heterogeneity triple negative breast cancer available treatments are limited, being chemotherapy in the first line of use. Despite advances in the search for new treatments, there is still a lack of effective therapies, being the metastatic disease the principal cause of breast cancer mortality. Therefore, it is critical to develop a new and effective strategies to inhibit metastasis. The Rho GTPase Rac has been identified as a promising target for anti-metastatic cancer therapy as it has been shown to play key roles in metastatic cancer cells dynamics as: cellular adhesion, migration, proliferation, survival and invasion. To this extent, in an effort to find a compound with increased Rac inhibitory capacity our group developed Ehop-016 derivatives HV-107 and HV-118. Previously we have reported HV-107 and HV-118 to affect cell viability promoting a G2-M cell cycle arrest with a sub-G1 population indicative of cell death in MDA-MB-231. Also, an increase of caspases activity validating apoptosis as a mechanism of cell death was shown. In addition, a decrease in tumor growth and metastasis by ~35 to 40% in an in vivo study using HV-118 at 1 mg/kg body weightwas also reported. Currently, through pulldown assays we have showed HV-107 and HV-118 to inhibit Rac activity at~500-2000 nM and 10 nM respectively in MDA-MB-231 and MDA-MB-468 breast cancer cells. Using trypan blue excision assay HV-107(>500 nM) and HV-118(>50 nM) were shown to affect cell viability promoting a G2-M cell cycle arrest in MDA-MB-468. We also demonstrated HV-107 and HV-118 to inhibit the direct downstream effector of Rac, PAK at >500 nM(HV-107) and >50 nM(HV-118) in MDA-MB-231 cells. In addition, HV-107 was also shown to increase Rho activity at concentrations significantly higher than the effective for Rac inhibition. Rho activity up-regulation has been reported to negatively affect migration of cancerous cells. Finally, we tested HV-107 in a mouse model of metastatic breast cancer. A decrease of ~ 40% in liver metastasis was shown for mice treated with 5 mg/kg BW HV-107. Taken together, our results indicate HV-107 and HV-118 are approximately 4-100 times more efficient than the parent compound Ehop-016 and have potential as anti-breast cancer metastasis therapeutics.

This study is supported by NIH Grant 1SC1GM122691, and PRINBRE P20GM103475 from NIGMS of the NIH to GVC

Citation Format: Grace Enid Velez Crespo, Eliud Hernandez, Suranganie Dharmawardhane, Cornelis Vlaar, Linnette Castillo, Lilia Kucheryavykh. Rac inhibitors for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2973.

Abstract P5-08-09: Characterization of the Rac/Cdc42 inhibitor MBQ-168 as an anti-cancer compound

Metastasis continues to be the primary cause of cancer-related death in women with breast cancer, needing targeted therapies to inhibit this process. Therefore, we developed inhibitors targeting the homologous Rho GTPases Rac1 and Cdc42, which direct the actin cytoskeletal changes required for cell migration/invasion; and thus, metastasis. We characterized the potent inhibitor, MBQ-167 that blocks both Rac1 and Cdc42 at IC50s 103 nM and 78 nM, respectively, in human HER2 (+) and triple-negative breast cancer (TNBC) cells. Consequently, MBQ-167 inhibits tumor growth and metastasis by ~90% in pre-clinical mouse models of breast cancer (Humphries-Bickley, et al., 2017). To improve the activity and solubility of MBQ-167, we synthesized a panel of derivatives, maintaining the 9-ethyl-3-(1H-1,2,3-triazol-1-yl)-9H-carbazole as the core for each derivative. Of the derivatives tested, MBQ-168 demonstrated improved solubility and comparable efficacy. Similar to MBQ-167, MBQ-168 induced actin cytoskeletal disintegration, cell rounding, and detachment to ultimately undergo anoikis. In 120hrs, MBQ-168 significantly inhibited the viability of MDA-MB-231 at a GI50 of 228nM and HER2+ MDA-MB-435 cells with a GI50 of 137 nM, without affecting the viability of Human Mammary Epithelial Cells (HMEC). In apoptosis assays, MBQ-168 treatment, at 500nM for 48 hrs, demonstrated a similar response to MBQ-167 by >4-fold increase in Caspase 3/7 activity in HER2 (+), and MDA-MB-231 and MDA-MB-468 TNBC cells. In wound healing assays, MBQ-168 also responded similar to MBQ-167 by a ~80% inhibition of breast cancer cell migration at 250nM and 500nM for 24hrs. Moreover, as quantified from Rac1.GTP pulldown assays, following 250nM treatment for 24hrs, MBQ-168 inhibited Rac1 activation in the attached cell population by ~70%, and in the detached cell population by ~100%, demonstrating a potent inhibition of Rac1 activation. In a preliminary study for relative efficacy in mice, MBQ-168 significantly reduced HER2+ MDA-MB-435 mammary tumor growth (~90%) at 5mg/kg BW via IP administration. In conclusion, MBQ-168 is an effective Rac inhibitor that reduces breast cancer cell viability, induces apoptosis, and inhibits breast cancer cell migration, actin cytoskeletal extensions, and Rac1 activation to result in a drastic reduction in mammary tumor growth in mice. We predict that the increased solubility of MBQ-168 will make it more bioavailable than MBQ-167. Thus, we have demonstrated that small structural modifications of MBQ-167 can affect the cytotoxic activity of carbazole derivatives with potential as anti-cancer drugs, and as tools to block Rac/Cdc42 activities in biological systems.

Citation Format: Julia Medina, Tatiana Matos, Luis Velazquez, Michael Rivera, Ailed Cruz-Collazo, Eliud Hernandez, Cornelis Vlaar, Suranganie Dharmawardhane. Characterization of the Rac/Cdc42 inhibitor MBQ-168 as an anti-cancer compound [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-08-09.

Genotype-driven pharmacokinetic simulations of warfarin levels in Puerto Ricans

Objectives The inter-individual variability of warfarin dosing has been linked to genetic polymorphisms. This study was aimed at performing genotype-driven pharmacokinetic (PK) simulations to predict warfarin levels in Puerto Ricans. Methods Analysis of each individual dataset was performed by one-compartmental modeling using WinNonlin®v6.4. The k e of warfarin given a cytochrome P450 2C9 (CYP2C9) genotype ranged from 0.0189 to 0.0075 h-1. K a and V d parameters were taken from literature. Data from 128 subjects were divided into two groups (i.e., wild-types and carriers) and statistical analyses of PK parameters were performed by unpaired t-tests. Results In the carrier group (n=64), 53 subjects were single-carriers and 11 double-carriers (i.e., *2/*2, *2/*3, *2/*5, *3/*5, and *3/*8). The mean peak concentration (Cmax) was higher for wild-type (0.36±0.12 vs. 0.32±0.14 mg/L). Likewise, the average clearance (CL) parameter was faster among non-carriers (0.22±0.03 vs. 0.17±0.05 L/h; p=0.0001), with also lower area under the curve (AUC) when compared to carriers (20.43±6.97 vs. 24.78±11.26 h mg/L; p=0.025). Statistical analysis revealed a significant difference between groups with regard to AUC and CL, but not for Cmax. This can be explained by the variation of k e across different genotypes. Conclusions The results provided useful information for warfarin dosing predictions that take into consideration important individual PK and genotyping data.

Genotype-driven pharmacokinetic simulations of warfarin levels in Puerto Ricans

OBJECTIVES

The inter-individual variability of warfarin dosing has been linked to genetic polymorphisms. This study was aimed at performing genotype-driven pharmacokinetic (PK) simulations to predict warfarin levels in Puerto Ricans.

METHODS

Analysis of each individual dataset was performed by one-compartmental modeling using WinNonlin®v6.4. The k _e of warfarin given a cytochrome P450 2C9 (CYP2C9) genotype ranged from 0.0189 to 0.0075 h^-1. K _a and V _d parameters were taken from literature. Data from 128 subjects were divided into two groups (i.e., wild-types and carriers) and statistical analyses of PK parameters were performed by unpaired t-tests.

RESULTS

In the carrier group (n=64), 53 subjects were single-carriers and 11 double-carriers (i.e., *2/*2, *2/*3, *2/*5, *3/*5, and *3/*8). The mean peak concentration (Cmax) was higher for wild-type (0.36±0.12 vs. 0.32±0.14 mg/L). Likewise, the average clearance (CL) parameter was faster among non-carriers (0.22±0.03 vs. 0.17±0.05 L/h; p=0.0001), with also lower area under the curve (AUC) when compared to carriers (20.43±6.97 vs. 24.78±11.26 h mg/L; p=0.025). Statistical analysis revealed a significant difference between groups with regard to AUC and CL, but not for Cmax. This can be explained by the variation of k _e across different genotypes.

CONCLUSIONS

The results provided useful information for warfarin dosing predictions that take into consideration important individual PK and genotyping data.

Abstract 4018: Interaction site elucidation of the Rac1/Cdc42 inhibitor, MBQ-167

Metastasis continues to be the primary cause of cancer-related death. Therefore, we focus on designing small molecules inhibitors to block metastasis. The Rho GTPase family members Rac1, and Cdc42 are critical regulators of cancer cell migration and invasion, and thus, metastasis. Rac1 is activated by Guanine Nucleotide Exchange Factors (GEFs), which promote the exchange of GDP to GTP. In most cancers, the homologous Rac1 and Cdc42 are hyperactivated due to the overexpression of GEFs. Therefore, we designed inhibitors to block the activation and interaction of Rac1 and Cdc42 with their GEFs. Our lead compound MBQ-167, is a dual inhibitor of Rac1 and Cdc42 with IC50s of 103 nM and 78 nM, respectively. MBQ-167 inhibited the viability and migration of metastatic cancer cells without affecting non-metastatic or non-cancer cells. Moreover, MBQ-167 reduced mammary tumor growth and metastasis of HER2 positive and triple-negative breast cancer cells in immunocompromised mice by ~ 90%. To further elucidate the mechanism of action of MBQ-167, we tested the hypothesis that MBQ-167 blocks the interaction of specific Rac1/Cdc42 GEFs by interaction with particular amino acid residues in the switch I and II homologous regions of Rac1 and Cdc42 proteins. Therefore, to achieve the objective of elucidating the interaction site of MBQ-167 on Rac1 and Cdc42, we used in silico analysis and Nuclear Magnetic Resonance (NMR) of MBQ-167 with Rac1 in a GDP bound state. These results were biochemically validated by pulldown assays using a G15A nucleotide-free mutant predicted to interact tightly with Rac1/Cdc42 GEFs. In silico, using Autodock Tools, MBQ-167 was docked to the GEF binding domain of Rac1 and Cdc42 with low binding energy, indicating a tight interaction. For the NMR structural analyses, Rac1 was isotopically labeled with 15N and titrated with several concentrations of MBQ-167, at ratios of 1:1, 1:2, 1:3, and 1:4. We were able to detect chemical shift perturbations in key residues in the switch I and II regions that interact with Rac1/Cdc42 GEFs and regulate the activity. Moreover, these perturbations were more intense with increasing amounts of MBQ-167, confirming the specificity of the interaction. Therefore, our data signify the direct interaction of MBQ-167 with Rac1, thus validating the role of MBQ-167 as a specific Rac1/Cdc42 inhibitor.

Citation Format: Julia I. Medina, Marvin Bayro, Eliud Hernandez, Cornelis Vlaar, Ricardo Gonzalez, Suranganie Dharmawardhane. Interaction site elucidation of the Rac1/Cdc42 inhibitor, MBQ-167 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4018.

Pharmacokinetics of the Rac/Cdc42 Inhibitor MBQ-167 in Mice by Supercritical Fluid Chromatography-Tandem Mass Spectrometry

The Rho GTPases Rac and Cdc42 are potential targets against metastatic diseases. We characterized the small molecule MBQ-167 as an effective dual Rac/Cdc42 inhibitor that reduces HER2-type tumor growth and metastasis in mice by ∼90%. This study reports the pharmacokinetics and tissue distribution of MBQ-167 following intraperitoneal and oral single-dose administrations. We first developed and validated a bioanalytical method for the quantitation of MBQ-167 in mouse plasma and tissues by supercritical fluid chromatography coupled with electrospray ionization tandem mass spectrometry. MBQ-167 was rapidly distributed into the kidneys after intraperitoneal dosing, whereas oral administration resulted in higher distribution to lungs. The elimination half-lives were 2.17 and 2.6 h for the intraperitoneal and oral dosing, respectively. The relative bioavailability of MBQ-167 after oral administration was 35%. This investigation presents the first analysis of the pharmacokinetics of MBQ-167 and supports further preclinical evaluation of this drug as a potential anticancer therapeutic.

Abstract 1997: The Rac inhibitors HV-107 and HV-118 as potential therapeutics for metastatic breast cancer

Breast cancer is the first cause of death in women globally. Metastatic breast cancer is stimated to affect more than a quarter of million of women in the US. Due to the lack of effective treatment, metastasis remains the main cause of breast cancer mortality. Therefore, it is imperative to develop novel effective strategies against metastasis. A promising target for anti-metastatic therapy is the Rho GTPase Rac because it plays a key role in metastatic cancer progression by regulating cellular processes such as adhesion, migration, proliferation and survival. Our group developed Ehop-016, a small molecule that inhibits Rac in metastatic breast cancer cells with an IC50=1µM and significantly reduces tumor growth, angiogenesis, and metastasis in a mouse model of metastatic breast cancer. However, its relative bioavailability is moderate and should be improved. Therefore, to find a compound with increased potency and bioavailability, we tested several Ehop-016 derivatives. Using Rac pulldown assays we show that HV-107 and HV-118 inhibit Rac activation by 60% in MDA-MB-231 and MDA-MB-435 metastatic breast cancer cells at 100 and 250nM, respectively. MTT assays show HV-107 (at ≥500nM) and HV-118 (at ≥50nM) significantly inhibit metastatic breast cancer cell viability, while showing minimal toxicity towards non-cancerous cells. Cell cycle analysis by flow cytometry demonstrates a G2-M arrest and a prominent sub-G1 population, indicative of cell death, in metastatic breast cancer cells treated with HV-107 (1000 nM) and HV-118 (100 nM). To evaluate apoptosis as a potential cell death mechanism, we measured caspase 3 activity. Our results show HV-107 and HV-118 significantly induce caspase 3 activity by approximately 1.6-fold at 1000 and 100nM, respectively in metastatic breast cancer cells. Therefore, these Rac inhibitors affect cell viability by inhibiting cell cycle progression and inducing apoptosis. Finally, we tested HV-118 (at 1mg/kg BW) in a mouse model of metastatic breast cancer and found a 30% reduction in tumor growth and a 90% inhibition in metastasis. Taken together, our results indicate HV-107 and HV-118 have potential as anti-breast cancer metastasis therapeutics. This study was supported by awards from the Susan Komen for the Cure, NIH/NIMHHD U54MD008149, and the Puerto Rico Science and Technology Trust to SD; NIH/NCRR R25GM061838 to UPR MSC; NIH/NIMHHD RCMI 8G12MD007583RCMI, Title V PPOHA 031M10505 and Title V Cooperative P031S130068 from U.S. Department of Education to UCC; and and PRINBRE (NIH/NIGMS P20GM103475-13) Sub-Award to LCP.

Citation Format: Grace E. Velez, Cornelis Vlaar, Eliud Hernandez, Anibal Valentin, Linette Castillo-Pichardo, Suranganie Dharmawardhane. The Rac inhibitors HV-107 and HV-118 as potential therapeutics for metastatic breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1997.

Abstract 4185: The novel Rac inhibitor HV-107 as a potential therapeutic for metastatic breast cancer

Breast cancer is the first cause of death in women globally. Metastatic breast cancer, which occurs when cancer cells migrate from the primary tumor and establish in distant organs, is estimated to affect more than a quarter of a million of women in the US. Regrettably, metastatic breast cancer still lacks effective treatment and remains the principal cause of breast cancer mortality. Therefore, it is imperative to develop new and more effective strategies to inhibit metastasis. A promising target for anti-metastatic cancer therapy is the Rho GTPase Rac because it plays a key role in the regulation of cellular adhesion, migration, proliferation and survival; processes which promote tumorigenesis and metastasis. Recently, our group developed Ehop-016, a small molecule that inhibits Rac in metastatic breast cancer cells with an IC50 of 1µM and reduces the activity of its downstream effector p21-activated kinase (PAK). Ehop-016 also inhibits tumor growth, angiogenesis, and metastasis in a mouse model of metastatic breast cancer. However, its relative bioavailability is moderate and should be further improved. Therefore, in an effort to find a compound with greater inhibitory capacity and bioavailability, we tested several Ehop-016 derivatives for their activity against Rac and their toxicity towards metastatic breast cancer cells. Using Rac pulldown assays we show that HV-107 at 250nM inhibits Rac activation by 55% in MDA-MB-231 and MDA-MB-435 metastatic breast cancer cells. The effects of HV-107 on cell viability were tested by MTT assays and our results indicate HV-107 at ≥500nM significantly inhibits metastatic breast cancer cell viability, while showing minimal toxicity towards non-cancerous mammary epithelial cells. We also measured caspase 3 activity, in order to evaluate apoptosis as a potential mechanism of HV-107-induced cell death. Our results show HV-107 at 1000nM causes a significant 1.5 fold increase in caspase 3 activity in MDA-MB-231 cells, indicating HV-107 affects cell viability by inducing apoptosis. Finally, we tested HV-107 in a mouse model of metastatic breast cancer and found a 25% reduction in tumor growth in mice treated with 5mg/kg BW HV-107. Taken together, our results suggest HV-107 is approximately four times more efficient than the parent compound Ehop-016 and has potential as anti-breast cancer metastasis therapeutic.

This study was supported by awards from the Susan Komen for the Cure, NIH/NIMHHD U54MD008149, and the Puerto Rico Science and Technology Trust to SD; NIH/NCRR R25GM061838 to UPR MSC; NIH/NIMHHD RCMI 8G12MD007583RCMI, Title V PPOHA 031M10505 and Title V Cooperative P031S130068 from U.S. Department of Education to UCC; and PRINBRE (NIH/NIGMS P20GM103475-13) Sub-Award to LCP.

Citation Format: Grace E. Velez Crespo, Eliud Hernández, Cornelis Vlaar, Suranganie Dharmawardhane, Linette Castillo-Pichardo. The novel Rac inhibitor HV-107 as a potential therapeutic for metastatic breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4185.

Abstract 4923: Pharmacokinetics of the metastatic cancer inhibitor MBQ-167 in mice

Metastasis is the principal cause of death for most cancer patients; however, effective treatment options are limited. The Rho GTPases Rac and Cdc42 are critical regulators of cancer cell migration and invasion; processes required for metastatic progression. Hence, targeting of these pivotal regulators is a rational approach for novel metastasis focused therapy design. We previously characterized the small molecule MBQ-167 as a novel Rac/Cdc42 inhibitor that inhibits mammary tumor growth and metastasis in immunocompromised mice by ~90%, which is ten times more potent than other currently available Rac inhibitors (Humphries-Bickley, et al., 2017). However, further studies are needed to determine the pharmacokinetic (PK) parameters of MBQ-167 in rodents to understand the mechanisms of drug distribution and elimination of this compound. The purpose of this study was to determine the pharmacokinetics and bioavailability of MBQ-167 in a single dose input scheme (10 mg/kg BW) following intraperitoneal (IP) and oral gavage (PO) administration. The drug was administered to BALB/c mice (4 mice/group) and plasma was collected at 0.5, 1, 3, 6, 9, and 12 hours after IP or PO administration. We developed and validated a bioanalytical method using supercritical fluid chromatography (SFC) coupled with electrospray ionization tandem mass spectrometry (MS/MS) for the detection of MBQ-167 in plasma. SFC-MS/MS was selected because it uses supercritical carbon dioxide (SCO2) as the mobile phase and offers advantages such as high sensitivity, increased resolution, and rapid analysis times. Pharmacokinetic parameters were obtained by mono-compartmental and bi-compartmental analysis for IP and PO dosing respectively using WinNolin® software, Version 7.0. Preliminary pharmacokinetic analysis revealed that the area under the curve (AUC0-∞) was 749 ng·hr/mL and 255 ng·hr/mL for IP and PO dosing respectively. The elimination half-life (t1/2) was 2.4 hours for IP dosing and the mean residence time (MRT) was 3.4 hours and 2.3 hours for the IP and PO dosing respectively. The maximum plasma drug concentration (Cmax) was 220 ng/mL after IP administration, compared to 127 ng/mL following PO administration. Furthermore, the time-to-peak for both administration routes was 30 minutes. The relative bioavailability of MBQ-167 after oral gavage administration was 34%. This study presents the first analysis of the pharmacokinetics of the Rac/Cdc42 inhibitor MBQ-167 in mice and it supports the continued development of this drug as a potential anti-cancer therapeutic.

Citation Format: Maria del Mar Maldonado, Linette Castillo-Pichardo, Joseph Bloom, Jorge Duconge, Jose F. Rodriguez-Orengo, Eliud Hernandez-O'Farrill, Cornelis Vlaar, Suranganie Dharmawardhane. Pharmacokinetics of the metastatic cancer inhibitor MBQ-167 in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4923.

Abstract B094: The dual Rac/Cdc42 inhibitor MBQ-167 and derivatives as anticancer compounds

Metastatic disease lacks effective treatments, and remains the primary cause of mortality from epithelial cancers. The Rho family GTPases Rac and Cdc42 and their downstream effector p21-activated kinase (PAK) are pivotal regulators of metastatic cancer cell migration and invasion; thus, overexpression of Rac/Cdc42/PAK has been correlated with reduced patient survival in breast, gastric, and lung cancer. Our studies on the efficacy and pharmacokinetics of the Rac inhibitor EHop-016 (US patents # 8,884,006 B2; 9,278,956B1) validated the development of Rac and Cdc42 inhibitors as anti-metastatic cancer therapeutics. To improve the pharmacologic utility of EHop-016, structural derivatives were screened for enhanced efficacy and bioavailability. We recently identified a dual Rac and Cdc42 inhibitor, MetaBloq(MBQ)-167, which inhibits Rac and Cdc42 activation with IC50s of 103 nM for Rac inhibition and 78 nM for Cdc42 inhibition. Moreover, MBQ-167 is specific to cancer cells that have undergone epithelial-to-mesenchymal transition (EMT), but not epithelial cancer cells or noncancer cells. In metastatic cancer cells, MBQ-167 induces a unique phenotype of loss in cell polarity, cell surface actin extensions, and cell-substrate attachments to undergo anoikis (apoptosis due to inadequate cell-matrix interactions). In vivo, MBQ-167 inhibits HER2 type mammary tumor growth and metastasis in immunocompromised mice by ~90-100% (Humphries-Bickley et al., Mol Cancer Ther 2017; patent applications US 15/499532, PCT/US17/29921). In this study, we have further tested the pharmacokinetics and utility of MBQ-167 in additional models of cancer and screened MBQ-167 derivatives for their utility as Rac/Cdc42 inhibitors. Similar to the results with HER2 type breast cancer, in severe combined immunodeficiency (SCID) mice with mammary fat pad tumors from the triple-negative MDA-MB-231 human breast cancer cell line, the effect of MBQ-167 saturated at 1 mg/kg BW with a 80% reduction in tumor growth and a 100% reduction in metastasis. In gastric cancer, MBQ-167 reduced the viability of metastatic NCI-N87 gastric cancer cells, induced anoikis without affecting the AGS nonmetastatic gastric cancer cells, and inhibited tumor growth in SCID mice. We have screened a range of MBQ-167 derivatives for cell viability and the “anoikis” phenotype and isolated 4 compounds that reduced breast cancer cell viability with GI50s in the nM range. From this screen, MBQ-14 acts similar to MBQ-167, and thus is considered to be a viable inhibitor for further investigation. We have developed a quantitative method for identifying MBQ-167 and MBQ-14 from mouse plasma using ultra-performance convergence chromatography (UPC2)/MS/MS, and find that MBQ-167 is bioavailable in mouse plasma with a half-life of ~4h following oral or intraperitoneal administration. Overall our data demonstrate the utility of further developing MBQ-167 and derivatives as anti-metastatic cancer therapeutics.

Citation Format: Linette Castillo-PIchardo, Maria Del Mar Maldonado, Jean Ruiz-Calderon, Jose F. Rodriguez-Orengo, Eliud Hernandez, Cornelis Vlaar, Surangani F. Dharmawardhane Flanagan. The dual Rac/Cdc42 inhibitor MBQ-167 and derivatives as anticancer compounds [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B094.

Abstract 3076: Characterization of an improved derivative of the Rac/PAK inhibitor EHop-016 in breast cancer

The expression and activities of the Rho GTPases Rac and Cdc42, and their downstream effector P21-activated kinase (PAK), have been correlated with metastatic cancer. Our published studies with the Rac/PAK inhibitor EHop-016 demonstrate the validity of using Rac inhibitors as anti metastatic cancer therapeutics. However, the relatively high effective concentrations (Rac activity IC50 1μM, tumor inhibition at 25 mg/kg body weight (BW)), and the moderate bioavailability (∼30%, t1/2 4.5h) of EHop-016 need improvement. Therefore, we developed EHop-016 derivatives and identified EHop-167 as a Rac inhibitor at nM concentrations. Unlike EHop-016, which does not substantially change breast cancer cell shape, but only reduces cell surface actin based invadopodia, EHop-167 induced a marked decrease in breast cancer cell polarity, cell surface extensions, and cell-extracellular matrix (ECM) attachments (focal adhesions). This phenotype of cell rounding and detachment in response to EHop-167 was demonstrated only by breast cancer cell lines that have undergone epithelial to mesenchymal transition, but not by epithelial breast cancer cells, or MCF-10A mammary epithelial cells. As assessed by pulldown assays and western blotting, Rac and PAK activities were reduced by 80-90% in response to 250 nM EHop-167, in the detached cells. As demonstrated by caspase assays, the cell rounding and detachment from the ECM ultimately resulted in anoikis (cell death due to loss of focal adhesions). Accordingly, Transwell assays of mesenchymal breast cancer cells following 250 nM Ehop-167 showed a ∼90% reduction in cell migration in the detached breast cancer cells, and a ∼60% inhibition in the attached cells. EHop-167 also reduced the mammosphere formation efficiency of metastatic cancer cells by 50%, indicating an inhibitory effect on cancer stem cells. To determine the in vivo efficacy of EHop-167, athymic nude mice, bearing mammary fatpad tumors of MDA-MB-435 metastatic cancer cells, were treated 3X a week with 0, 1, or 10 mg/kg BW EHop-167 for 50 days. Treatment with 1.0 mg/kg BW EHop-167 resulted in a 50% reduction in tumor growth, while 10.0 mg/kg BW EHop-167 induced an ∼95% reduction in tumor growth, compared to controls. Additionally, these mice did not show gross signs of toxicity or significant weight loss. Since the parental compound EHop-016 has no anticancer effects at similar concentrations, we conclude that EHop-167 is an improved Rac/PAK inhibitor that holds promise as an anti metastatic breast cancer therapeutic.

Citation Format: Linette Castillo-Pichardo, Tessa Humphries-Bickley, Ingrid Forrestier-Roman, Luis Borrero-Garcia, Fabiola Pagan Melendez, Eliud Hernandez, Cornelis Vlaar, Luis A. Cubano, Surangani Dharmawardhane. Characterization of an improved derivative of the Rac/PAK inhibitor EHop-016 in breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3076.

Abstract A141: A novel inhibitor of malignant signaling in metastatic breast cancer

The Rho GTPase Rac is a pivotal regulator of cancer cell migration and invasion; processes required for metastatic progression. We previously characterized the small molecule EHop-016 as a novel Rac inhibitor in metastatic breast cancer cells and recently reported that EHop-016 was effective at reducing tumor growth, metastasis, and angiogenesis in nude mice at 25 mg/kg bodyweight (BW) (Castillo-Pichardo, et al. 2014). We also determined the pharmacokinetics and bioavailability of EHop-016, and reported that EHop-016 is rapidly cleared from mouse plasma with a half-life of ∼5 hrs and ∼30% bioavailability (Humphries-Bickley, et al., 2015). To improve the bioavailability and efficacy of EHop-016, we synthesized and screened a number of derivatives, from which EHop-016A was identified as a potent Rac inhibitor at nM concentrations. Moreover, as determined from immunofluorescence and brightfield microscopy of several breast cancer cell lines, EHop-016A has a dramatic effect on cell morphology by inducing a loss of cell polarity, and inhibiting cell surface actin-based extensions and focal adhesions, to ultimately result in the detachment of cells from the extracellular matrix (ECM). In addition, EHop-016A reduces breast cancer cell migration in a transwell assay. EHop-016A also decreases mammosphere formation, indicating an inhibitory effect on breast cancer stem cell-like properties. The effect of EHop-016A on metastatic cancer cell viability was determined via MTT assays. EHop-016A decreases cell viability with a GI50 of 150 nM and 110 nM in MDA-MB-435 and MDA-MB-231 human metastatic cancer cell lines respectively. Western blotting demonstrated that EHop-016A decreases anti-apoptotic proteins BCL-2 and BCL-xL without affecting their gene expression, as quantified by qPCR. Consequently, EHop-016A increases pro-apoptotic caspase 3/7 activity. These results indicate that the EHop-016A induced cell rounding and detachment from the substratum results in anoikis (apoptosis due to dissolution of integrin-mediated cell to ECM attachments). Therefore, this new small molecule compound has potential as an inhibitor of metastatic breast cancer progression, and warrants further investigation as an anticancer agent.

Citation Format: Tessa Humphries-Bickley, Linette Castillo-Pichardo, Luis Borrero-Garcia, Ingrid Forestier-Roman, Luis Cubano, Eliud Hernandez-O'Farrill, Cornelis Vlaar, Suranganie Dharmawardhane. A novel inhibitor of malignant signaling in metastatic breast cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A141.

Pharmacokinetics of Rac inhibitor EHop-016 in mice by ultra-performance liquid chromatography tandem mass spectrometry

The Rho GTPase Rac is an important regulator of cancer cell migration and invasion; processes required for metastatic progression. We previously characterized the small molecule EHop-016 as a novel Rac inhibitor in metastatic breast cancer cells and recently found that EHop-016 was effective at reducing tumor growth in nude mice at 25 mg/kg bodyweight (BW). The purpose of this study was to compare the pharmacokinetics and bioavailability of EHop-016 at different dosages in a single dose input scheme (10, 20 and 40 mg/kg BW) following intraperitoneal (IP) and oral gavage (PO) administration to nude mice. We developed and validated a rapid and sensitive method for the quantitation of EHop-016 in mouse plasma by ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC/MS/MS). Separation was carried out on an Agilent Poroshell 120 EC-C18 column (3.0 mm × 50 mm) using organic and aqueous mobile phases. EHop-016 was identified from its accurate mass and retention time from the acquired full-scan chromatogram and quantified by its peak area. The validated method was linear (R(2)>0.995) over the range of 5-1000 ng/mL (1/x(2) weighting). Pharmacokinetic parameters were obtained by non-compartmental analysis using WinNonlin. The area under the curve (AUC₀-∞) ranged from 328 to 1869 ng h/mL and 133-487 ng h/mL for IP and PO dosing, respectively. The elimination half-life (t₁/₂) ranged from 3.8-5.7 h to 3.4-26.8 h for IP and PO dosing, respectively. For both IP and PO administration, the AUC₀-∞values were proportional to the tested doses demonstrating linear PK profiles. The relative bioavailability of EHop-016 after oral gavage administration ranged from 26% to 40%. These results support further preclinical evaluation of EHop-016 as a new anti-cancer therapy.

The Rac Inhibitor EHop-016 Inhibits Mammary Tumor Growth and Metastasis in a Nude Mouse Model

Metastatic disease still lacks effective treatments, and remains the primary cause of cancer mortality. Therefore, there is a critical need to develop better strategies to inhibit metastatic cancer. The Rho family GTPase Rac is an ideal target for anti-metastatic cancer therapy, because Rac is a key molecular switch that is activated by a myriad of cell surface receptors to promote cancer cell migration/invasion and survival. Previously, we reported the design and development of EHop-016, a small molecule compound, which inhibits Rac activity of metastatic cancer cells with an IC₅₀ of 1 μM. EHop-016 also inhibits the activity of the Rac downstream effector p21-activated kinase (PAK), lamellipodia extension, and cell migration in metastatic cancer cells. Herein, we tested the efficacy of EHop-016 in a nude mouse model of experimental metastasis, where EHop-016 administration at 25 mg/kg body weight (BW) significantly reduced mammary fat pad tumor growth, metastasis, and angiogenesis. As quantified by UPLC MS/MS, EHop-016 was detectable in the plasma of nude mice at 17 to 23 ng/ml levels at 12 h following intraperitoneal (i.p.) administration of 10 to 25 mg/kg BW EHop-016. The EHop-016 mediated inhibition of angiogenesis In Vivo was confirmed by immunohistochemistry of excised tumors and by In Vitro tube formation assays of endothelial cells. Moreover, EHop-016 affected cell viability by down-regulating Akt and Jun kinase activities and c-Myc and Cyclin D expression, as well as increasing caspase 3/7 activities in metastatic cancer cells. In conclusion, EHop-016 has potential as an anticancer compound to block cancer progression via multiple Rac-directed mechanisms.

Abstract A155: The Rac and PAK inhibitor EHop-016 inhibits mammary tumor growth and metastasis in a nude mouse model

The Rho GTPase Rac is a central regulator of cancer cell migration/invasion that has been implicated with cancer metastasis. Therefore, we designed and developed small molecule compounds that specifically target Rac in metastatic cancer cells. We recently reported the characterization of EHop-016 as a Rac inhibitor in metastatic cancer cells, where EHop-016 was shown to inhibit Rac activity with an IC50 of 1 μM. At higher concentrations (>10 μM) EHop-016 reduced cell viability and inhibited the related Rho GTPase Cdc42, but not Rho. EHop-016 decreased the activation of Rac by the oncogenic guanine nucleotide exchange factor Vav, the activity of the Rac effector p21-activated kinase (PAK), and the extension of actin cytoskeletal structures and migration of metastatic cancer cells. Next, we determined the efficacy of EHop-016 in vivo, using a mouse model of experimental metastasis. Green fluorescent protein (GFP) tagged MDA-MB-435 human metastatic cancer cells were inoculated at the mammary fat pad of nude mice and treated with 0, 5, 10, 25, or 40 mg/kg body weight (BW) EHop-016 3X a week for ∼8 weeks. Mammary tumor growth and metastases in lungs, spleens, kidneys, livers, hearts, and femurs were quantified by fluorescence image analysis. At concentrations >10 mg/kg BW, EHop-016 significantly inhibited mammary tumor growth and metastasis to distant organs. EHop-016 had no effect on mouse weight or their gross phenotype, indicating that EHop-016 did not exert toxic effects in athymic nude mice. This data demonstrate that EHop-016 and derivatives hold promise for further development as targeted anti-cancer therapeutics.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):A155.

Citation Format: Linette Castillo-Pichardo, Tessa Humphries-Bickley, Eliud Hernandez, Columba de la Parra, Luis Cubano, Cornelis Vlaar, Surangani F. Dharmawardhane Flanagan. The Rac and PAK inhibitor EHop-016 inhibits mammary tumor growth and metastasis in a nude mouse model. [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 A155.

Development of EHop-016: a small molecule inhibitor of Rac

The Rac inhibitor EHop-016 was developed as a compound with the potential to inhibit cancer metastasis. Inhibition of the first step of metastasis, migration, is an important strategy for metastasis prevention. The small GTPase Rac acts as a pivotal binary switch that is turned "on" by guanine nucleotide exchange factors (GEFs) via a myriad of cell surface receptors, to regulate cancer cell migration, survival, and proliferation. Unlike the related GTPase Ras, Racs are not usually mutated, but overexpressed or overactivated in cancer. Therefore, a rational Rac inhibitor should block the activation of Rac by its upstream effectors, GEFs, and the Rac inhibitor NSC23766 was developed using this rationale. However, this compound is ineffective at inhibiting the elevated Rac activity of metastatic breast cancer cells. Therefore, a panel of small molecule compounds were derived from NSC23766 and screened for Rac activity inhibition in metastatic cancer cells. EHop-016 was identified as a compound that blocks the interaction of Rac with the GEF Vav in metastatic human breast cancer cells with an IC50 of ~1μM. At higher concentrations (10μM), EHop-016 inhibits the related Rho GTPase Cdc42, but not Rho, and also reduces cell viability. Moreover, EHop-016 inhibits the activation of the Rac downstream effector p21-activated kinase, extension of motile actin-based structures, and cell migration. Future goals are to develop EHop-016 as a therapeutic to inhibit cancer metastasis, either individually or in combination with current anticancer compounds. The next generation of EHop-016-based Rac inhibitors is also being developed.

Abstract 3251: Characterization of a novel Rac inhibitor as an anti cancer metastasis compound

The objective of this project is to design novel therapeutics targeting cancer metastasis, the most deadly aspect of epithelial cancers. Our previous studies have shown that Rac, a key signaling intermediate that regulates actin cytoskeletal changes during cell migration/invasion and cancer metastasis, is associated with high cancer metastatic efficiency. Since Rac proteins are activated by GDP/GTP exchange, inhibition of the interaction of Rac with its guanine nucleotide exchange factors (GEF) is expected to inhibit Rac activity. Since the known Rac inhibitor NSC-23766 is not effective at therapeutically useful concentrations, we synthesized novel NSC-23766 derivatives. Results show that the new inhibitor EHop-016 is 100-fold more efficient than the parent compound at inhibiting Rac activity of metastatic cancer cells without affecting the activity of the related GTPase, Rho. EHop-016 inhibited Rac activity of metastatic cancer cells with an IC50 of 0.78 microM. Cell viability assays, performed to test for the toxicity of this compound, demonstrated that at concentrations below 5 microM, EHop-016 did not affect mammary epithelial cell (MCF-10A) viability and decreased proliferation of metastatic cancer cells (MDA-MB-435) by only 20%. We conclude that EHop-16 is a potent Rac inhibitor with promise of further development as a small molecule inhibitor of cancer cell invasion, and thus, metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3251. doi:10.1158/1538-7445.AM2011-3251